Patent Publication Number: US-2022218994-A1

Title: Apparatus with sequentially implanted stimulators

Description:
CROSS REFERENCE 
     This application is a continuation of U.S. patent application Ser. No. 16/539,977, filed Aug. 13, 2019, now U.S. Pat. Ser. No. ______; which is a continuation of PCT Application No. PCT/US2018/019522, filed Feb. 23, 2018; which claims priority U.S. Provisional Patent Application No. 62/463,328, filed Feb. 24, 2017; the contents of which are incorporated herein by reference in their entirety for all purposes. 
    
    
     DESCRIPTION OF THE INVENTION 
     Related Applications 
     This application is related to: U.S. patent application Ser. No. 14/424,303, titled “Wireless Implantable Sensing Devices”, filed Feb. 26, 2015 [Docket nos. S12-360; NAL-006-US]; U.S. patent application Ser. No. 14/975,358, titled “Method and Apparatus for Minimally Invasive Implantable Modulators”, filed Dec. 18, 2015 [Docket nos. 47476.703.301; NAL-005-US]; U.S. patent application Ser. No. 15/264,864, titled “Method and Apparatus for Versatile Minimally Invasive Neuromodulators”, filed Sep. 14, 2016 [Docket nos. 47476-704.301; NAL-007-US]; U.S. patent application Ser. No. 15/385,729, titled “Method and Apparatus for Neuromodulation Treatments of Pain and Other Conditions”, filed Dec. 20, 2016 [Docket nos. 47476.705.301; NAL-008-US]; International PCT Patent Application Serial Number PCT/US2016/016888, titled “Medical Apparatus Including an Implantable System and an External System”, filed Feb. 5, 2016 [Docket nos. 47476-706.601; NAL-011-PCT-Parent]; International PCT Patent Application Serial Number PCT/US2016/051177, titled “Apparatus for Peripheral or Spinal Stimulation”, filed Sep. 9, 2016 [Docket nos. 47476-707.601; NAL-012-PCT]; International PCT Patent Application Serial Number PCT/US2017/017978, titled “Apparatus with Enhanced Stimulation Waveforms”, filed Feb. 15, 2017 [Docket nos. 47476-708.601; NAL-014-PCT-Parent]; U.S. Provisional Patent Application Ser. No. 62/311,297, titled “Devices and Methods for Positioning External Devices in Relation to Implanted Devices”, filed Mar. 21, 2016 [Docket nos. 47476-709.101; NAL-016-PR1]; U.S. Provisional Patent Application Ser. No. 62/341,418, titled “Methods and Systems for Insertion and Fixation of Implantable Devices”, filed May 25, 2016 [Docket nos. 47476-710.101; NAL-013-PR1]; U.S. Provisional Patent Application Ser. No. 62/363,742, titled “Methods and Systems for Treating Pelvic Disorders and Pain Conditions”, filed Jul. 18, 2016 [Docket nos. 47476-711.101; NAL-017-PR1]; and U.S. Provisional Patent Application Ser. No. 62/441,056, titled “Stimulation Apparatus”, filed Dec. 30, 2016 [Docket nos. 47476-712.101; NAL-015-PR1]; the content of each of which is incorporated herein by reference in its entirety for all purposes. 
     FIELD OF THE INVENTION 
     The present invention relates generally to a medical apparatus for a patient, and in particular, an apparatus that provides sequentially implanted stimulators that perform both a stimulation trial period as well as a long-term stimulation therapy. 
     BACKGROUND OF THE INVENTION 
     Implantable devices that treat a patient and/or record patient data are known. For example, implants that deliver energy such as electrical energy, or deliver agents such as pharmaceutical agents are commercially available. Implantable electrical stimulators can be used to pace or defibrillate the heart, as well as modulate nerve tissue (e.g. to treat pain). Most implants are relatively large devices with batteries and long conduits, such as implantable leads configured to deliver electrical energy or implantable tubes (i.e. catheters) to deliver an agent. These implants require a fairly invasive implantation procedure, and periodic battery replacement, which requires additional surgery. The large sizes of these devices and their high costs have prevented their use in a variety of applications. 
     Nerve stimulation treatments have shown increasing promise recently, showing potential in the treatment of many chronic diseases including drug-resistant hypertension, motility disorders in the intestinal system, metabolic disorders arising from diabetes and obesity, and both chronic and acute pain conditions among others. Many of these implantable device configurations have not been developed effectively because of the lack of miniaturization and power efficiency, in addition to other limitations. 
     There is a need for apparatus, systems, devices and methods that provide one or more implantable devices and are designed to provide enhanced treatment of pain and other enhanced benefits. 
     SUMMARY 
     According to an aspect of the present inventive concepts, a stimulation apparatus for a patient comprises an external system configured to transmit transmission signals and implantable system configured to receive the transmission signals from the external system. The external system comprises a first external device comprising: at least one external antenna configured to transmit the transmission signals to the implantable system; an external transmitter configured to drive the at least one external antenna; an external power supply configured to provide power to at least the external transmitter; and an external controller configured to control the external transmitter. The implantable system comprises: at least one implantable lead for implanting under the skin of the patient and comprising at least one stimulation element configured to deliver stimulation energy to tissue of the patient, and a first implantable device. The first implantable device comprises: at least one implantable antenna configured to receive the transmission signals from the external system, the transmission signal comprising power and data; an implantable receiver configured to receive the transmission signals from the at least one implantable antenna; a first implantable connector for operably connecting to the at least one implantable lead; an implantable controller configured to deliver energy to the at least one stimulation element of the at least one implantable lead, the delivered energy provided by the transmission signal received from the external device; and an implantable housing surrounding at least the implantable controller and the implantable receiver. The implantable system comprises a second implantable device comprising: at least one implantable antenna configured to receive the transmission signals from the external system, the transmission signal comprising data; an implantable receiver configured to receive the transmission signals from the at least one implantable antenna; an implantable energy storage assembly comprising a battery and/or a capacitor; a second implantable connector for operably connecting to the at least one implantable lead; an implantable controller configured to deliver energy to the at least one stimulation element of the at least one implantable lead, the delivered energy provided by the implantable energy storage assembly; and an implantable housing surrounding at least the implantable controller and the implantable receiver. The first implantable device is configured to be attached to the at least one implantable lead for a first time period, and the second implantable device is configured to be attached to the at least one implantable lead for a second time period, subsequent to the first time period. 
     According to another aspect of the present inventive concepts, a stimulation apparatus for a patient comprises at least one implantable lead for implanting under the skin of the patient and comprising at least one stimulation element; an external system comprising: a first external device maintained outside of the patient and configured to transmit power and/or data; and an implantable system comprising: a first implantable device for implanting under the skin of the patient and configured to receive the power and/or data from the first external device; and a second implantable device for implanting under the skin of the patient. The first implantable device is configured to be attached to the at least one implantable lead for a first time period; and the second implantable device is configured to be attached to the at least one implantable lead for a second time period, subsequent to the first time period. 
     In some embodiments, the at least one implantable device comprises a single implantable lead, and the first implantable device and the second implantable device each attach to the single implantable lead. 
     In some embodiments, the at least one implantable lead comprises a first implantable lead and a second implantable lead, and the first implantable device attaches to the first implantable lead and the second implantable device attaches to the second implantable lead. The first implantable lead can be pre-attached to the first implantable device. The second implantable lead can be pre-attached to the second implantable device. 
     In some embodiments, the apparatus further comprises a filament extending from the first implantable device housing, and the filament operably attaches to the first implantable connector. 
     The apparatus can further comprise a fitting which surrounds the filament and the first implantable connector. 
     In some embodiments, the apparatus further comprises a filament extending from the second implantable device housing, and the filament operably attaches to the second implantable connector. The apparatus can further comprise a fitting which surrounds the filament and the second implantable connector. 
     In some embodiments, the at least one implantable lead comprises a proximal portion and a distal portion, and the distal portion is detachable from the proximal portion. The detachable distal portion can be configured to attach to the second implantable connector. The proximal portion can be pre-attached to the first implantable device. 
     In some embodiments, the first implantable device housing comprises a clam-shell design configured to be compressed to operably connect the first implantable connector to the at least one implantable lead. The apparatus can further comprise at least one gasket configured to seal the first implantable device to the at least one implantable lead. 
     In some embodiments, the apparatus further comprises a tool configured to slidingly engage and expand the first implantable connector, after which the at least one implantable lead is inserted into and operably connected to the first implantable connector. The tool can be configured to be removed after the at least one implantable lead is inserted into the first implantable connector. The apparatus can further comprise at least one gasket configured to seal the first implantable device to the at least one implantable lead. 
     In some embodiments, the apparatus further comprises a sleeve configured to slidingly receive the at least one implantable lead, slidingly engage the first implantable connector, and operably connect the at least one implantable lead to the first implantable connector. The sleeve can include multiple connecting segments which connect the at least one implantable lead to the first implantable connector. The apparatus can further comprise at least one gasket configured to seal the first implantable device to the at least one implantable lead. The at least one gasket can comprise connecting segments which operably connect the at least one implantable lead to the first implantable connector. 
     In some embodiments, the first implantable connector comprises frictionally engaging contacts which operably connect the at least one implantable lead to the first implantable connector. The frictionally engaging contacts can comprise contacts selected from the group consisting of: electromechanical brushes; interference connector; canted springs; conductive mesh; deformable fingers; and combinations thereof. The apparatus can further comprise at least one gasket configured to seal the first implantable device to the at least one implantable lead. 
     In some embodiments, the first implantable connector comprises rotating contacts which operably connect the at least one implantable lead to the first implantable connector. Each rotating contact can comprise a hinge, an extension arm and a conductive pin. Each rotating contact can pass through the first implantable device housing during rotation. The housing can comprise holes through which the rotating contacts pass through. The apparatus can further comprise at least one gasket configured to seal the first implantable device to the at least one implantable lead. 
     In some embodiments, the first implantable connector comprises spring-loaded contacts which operably connect the at least one implantable lead to the first implantable connector. The apparatus can further comprise a compression element which compresses the first implantable connector around the at least one implantable lead. The apparatus can further comprise at least one gasket configured to seal the first implantable device to the at least one implantable lead. 
     In some embodiments, the first implantable device housing comprises a rollable housing configured to circumferentially surround the at least one implantable lead. The housing can comprise a flexible material and/or hinged segments. 
     In some embodiments, the second time period comprises a longer duration than the first time period. 
     In some embodiments, the first implantable device is configured to receive power and data from the external system, and the second implantable device is configured to receive data from the external system. The second implantable device does not receive power from the external system. 
     In some embodiments, the first implantable connector and the second implantable connector comprise similar construction and arrangement. 
     In some embodiments, the first implantable connector and the second implantable connector comprise dissimilar construction and arrangement. The first implantable connector can be configured to provide a contamination-preventing seal about the at least one implantable lead for at least a first time period, and the second implantable connector can be configured to provide a contamination-preventing seal about the at least one implantable lead for a second time period, and the first time period is shorter than the second time period. The first time period can be less than or equal to 3 months. The second time period can be greater than or equal to 3 months. 
     In some embodiments, the first implantable device comprises an implantable energy storage assembly. The second implantable device energy storage assembly can have a greater energy storage capacity than the first implantable device energy storage assembly. The second implantable device energy storage assembly can have at least 10 times the energy storage capacity as the energy storage capacity of the first implantable device energy storage assembly. The first implantable device energy storage assembly can comprise an energy storage capacity of no more than 0.6 Joules, no more than 0.7 Joules, and/or no more than 40 Joules. The second implantable device energy storage assembly can comprise an energy storage capacity of at least 60 Joules, at least 700 Joules, and/or at least 4,000 Joules. 
     In some embodiments, the second implantable device energy storage assembly comprises an energy storage capacity of at least 60 Joules, at least 700 Joules, and/or at least 4,000 Joules. 
     In some embodiments, the transmission signals comprise a frequency between 10 MHz and 10.6 GHz. The transmission signal can comprise a frequency proximate to 40.68 MHz. 
     In some embodiments, the apparatus is configured to provide the stimulation energy in a waveform with an amplitude between 0.01 mA and 15 mA. The apparatus can be configured to provide the stimulation energy in a waveform with an amplitude between 0.01 mA and 10 mA. 
     In some embodiments, the apparatus is configured to treat hernia pain. At least one of the first implantable device or the second implantable device can deliver stimulation at a frequency less than or equal to 1 kHz. At least one of the first implantable device or the second implantable device can deliver stimulation at a frequency greater than or equal to 1 kHz. The at least one stimulation element can be configured to be positioned proximate nerves and/or their branches. The at least one stimulation element can be configured to deliver subcutaneous field stimulation. The at least one stimulation element can be configured to deliver transvascular stimulation. 
     In some embodiments, the apparatus is configured to treat knee pain. The at least one stimulation element can be configured to stimulate nerves innervating the knee and/or tissue surrounding the knee. The at least one stimulation element can be configured to deliver subcutaneous field stimulation. The at least one stimulation element can be configured to deliver transvascular stimulation. The at least one stimulation element can be configured to stimulate one or more nerves selected from the group consisting of: medial femoral cutaneous and/or infrapatellar cutaneous branches of saphenous nerve; constant articular branches of common peroneal, lateral retinacular nerve; lateral, medial, and/or anterior cutaneous femoral nerve, infrapatellar branch of saphenous nerve, medial and/or lateral retinacular nerve and/or articular branches of peroneal nerve; obturator, posterior tibial and/or sciatic nerves; tibial nerve; superior, middle and/or inferior genicular nerves; nerves arising from the common peroneal such as the superior lateral, inferior lateral, and/or recurrent genicular nerves; nerves arising from the obturator nerve such as the genicular branch of obturator; and nerves arising from the femoral nerve such as the saphenous nerve; and combinations thereof. 
     In some embodiments, the apparatus is configured to treat carpal tunnel syndrome. The apparatus can be configured to deliver stimulation to tissue selected from the group consisting of: median nerve tissue; ulnar nerve tissue; radial nerve tissue; and combinations thereof. 
     In some embodiments, least one of the first implantable device or the second implantable device comprises a sensor configured to produce a signal correlating to a level of contamination. The sensor can comprise a sensor selected from the group consisting of: pH sensor; optical sensor; chemical sensor; and combinations thereof. The apparatus can be configured to produce an alarm when detected contamination exceeds a threshold. 
     In some embodiments, the apparatus is configured to treat diabetic neuropathy. The apparatus can be configured to deliver stimulation to tibial nerve tissue. 
     In some embodiments, the apparatus is configured to treat pain. The apparatus can be configured to treat back pain. The apparatus can be configured to treat knee pain. 
     In some embodiments, the apparatus is configured to treat a type of pain selected from the group consisting of: back pain; joint pain; neuropathic pain; tennis elbow; muscle pain; shoulder pain; chronic, intractable pain of the back and/or lower limbs including unilateral or bilateral pain; neuropathic groin pain; perineal pain; phantom limb pain; complex regional pain syndrome; failed back surgery syndrome; cluster headaches; migraines; inflammatory pain; arthritis; abdominal pain; pelvic pain; and combinations thereof. 
     In some embodiments, the apparatus is configured to treat a pelvic dysfunction. The apparatus can be configured to treat overactive bladder. 
     In some embodiments, the apparatus is configured to treat a patient disease or disorder selected from the group consisting of: chronic pain; acute pain; migraine; cluster headaches; urge incontinence; pelvic dysfunction such as overactive bladder; fecal incontinence; bowel disorders; tremor; obsessive compulsive disorder; depression; epilepsy; inflammation; tinnitus; high blood pressure; heart failure; carpal tunnel syndrome; sleep apnea; obstructive sleep apnea; dystonia; interstitial cystitis; gastroparesis; obesity; mobility issues; arrhythmia; rheumatoid arthritis; dementia; Alzheimer&#39;s disease; eating disorder; addiction; traumatic brain injury; chronic angina; congestive heart failure; muscle atrophy; inadequate bone growth; post-laminectomy pain; liver disease; Crohn&#39;s disease; irritable bowel syndrome; erectile dysfunction; kidney disease; and combinations thereof. 
     In some embodiments, the apparatus is further configured as a diagnostic apparatus. The apparatus can further comprise a sensor configured to record diagnostic information. The first implantable device and/or the second implantable device can comprise the sensor. The first external device can comprise the sensor. The at least one implantable lead can comprise the sensor. 
     In some embodiments, the apparatus is configured to deliver stimulation energy to spinal cord tissue. 
     In some embodiments, the apparatus is configured to deliver energy selected from the group consisting of electrical energy; magnetic energy; electromagnetic energy; light energy; infrared light energy, visible light energy; ultraviolet light energy; mechanical energy; thermal energy; heat energy; cryogenic energy; sound energy; ultrasonic sound energy; high intensity focused ultrasound energy; low intensity focused ultrasound energy; subsonic sound energy; chemical energy; and combinations thereof. 
     In some embodiments, the apparatus is configured to randomly vary stimulation delivery. The apparatus can be configured to vary stimulation based on a probability distribution. 
     In some embodiments, the apparatus further comprises at least one functional element. The at least one functional element can comprise a sensor. The first implantable device and/or the second implantable device can comprise the sensor. The first external device can comprise the sensor. The at least one functional element can comprise a transducer. The first implantable device and/or the second implantable device can comprise the transducer. The first external device can comprise the transducer. 
     According to another aspect of the present inventive concepts, a method of providing stimulation therapy to a patient comprises (a) providing the stimulation apparatus according to any claim herein, (b) implanting a first implantable lead and the first implantable device in the patient, and connecting the first implantable lead to the first implantable device; (c) delivering stimulation energy to patient tissue via the first implantable device for a trial period; (d) detaching the first implantable lead from the first implantable device, explanting the first implantable device, implanting the second implantable device, and attaching an implantable lead to the second implantable device; and (e) delivering stimulation energy to the patient via the second implantable device for a therapy period. 
     In some embodiments, in step (d) the second implantable device is attached to the first implantable lead. 
     In some embodiments, the therapy period is of longer duration than the trial period. 
     In some embodiments, the trial period comprises a duration of at least 1 week. 
     In some embodiments, the trial period comprises a duration of at least 1 month. 
     In some embodiments, the trial period comprises a duration of at least 2 months. 
     In some embodiments, the trial period comprises a duration of at least 3 months. 
     In some embodiments, the therapy period comprises a duration of at least 3 months. 
     In some embodiments, during step (c), one or more stimulation parameters are varied. 
     In some embodiments, step (d) comprises detaching a first portion of the first implantable lead from a second portion of the first implantable lead. 
     In some embodiments, the at least one implantable lead comprises a distal portion including the at least one stimulation element and a proximal portion including at least one contact, and the at least one stimulation element and the at least one contact are operably connected. The distal portion can further comprise a flex circuit comprising one or more traces configured to operably connect the at least one stimulation element and the at least one contact. The distal portion can further comprise a covering surrounding the flex circuit, and the covering can comprise one or more recesses to expose the at least one stimulation element. The distal portion can further comprise a conductive rod and a layer stack applied to the conductive rod. The layer stack can comprise alternating layers of an insulator and a conductor, and an outer most layer of the layer stack can comprise the insulator. The alternating layers of insulator and conductor can be applied using one or more of the following deposition processes: sputtering; evaporation; dipping; plating; spraying; and chemical vapor deposition. The layer stack can comprise one or more recesses to expose a portion of the conductor rod and/or conductor layer, and the exposed portion of the conductor rod and/or conductor layer can comprise the at least one stimulation element. The conductive rod and/or conductor layer can be configured to operably connect to the at least one contact. 
     According to another aspect of the present inventive concepts, a method of treating a patient disease or disorder comprises providing a stimulation apparatus for a patient. The stimulation apparatus can comprise an implantable system. The implantable system can comprise an implantable lead comprising a distal portion including at least one stimulation element and a proximal portion including at least one contact, the at least one stimulation element and the at least one contact can be operably connected, and the at least one stimulation element can be configured to deliver stimulation energy to tissue of the patient. The implantable system can comprise an implantable device comprising a connector for operably connecting to the at least one contact of the implantable lead and a controller configured to deliver stimulation energy to the at least contact, and the at least one contact can be configured to deliver energy to the at least one stimulation element of the implantable lead. The method can comprise (a) implanting the implantable lead under the skin of the patient and operably connecting the connector of the implantable device to a first contact of the implantable lead; (b) delivering a minimum stimulation energy to patient tissue via a first stimulation element; (c) gradually increasing the minimum stimulation energy to achieve a therapeutic stimulation energy; (d) decreasing the therapeutic stimulation energy to the minimum stimulation energy; (e) operably disconnecting the connector from the first contact and operably connecting the connector to a second contact of the implantable lead; and (f) repeating (b) through (e) with remaining contacts of the implantable lead to achieve a therapeutic stimulation energy with remaining stimulation elements. 
     In some embodiments, the method further comprises (g) implementing a long-term therapy after a therapeutic stimulation energy is achieved with the final contact and final stimulation element, and the long-term therapy implements the therapeutic stimulation energy achieved with each contact and stimulation element. 
     According to another aspect of the present inventive concepts, a stimulation apparatus for a patient comprising: a first implantable device comprising an implantable lead, the implantable lead comprising at least one contact and at least one stimulation element, and the at least one contact and the at least one stimulation element are operably connected; a second implantable device; and a lead removal tool configured to remove the implantable lead from the first implantable device. The implantable lead can be configured to operably connect to the second implantable device once removed from the first implantable device. 
     In some embodiments, the first implantable device comprises a short-term implantable device. 
     In some embodiments, the second implantable device comprises a long-term implantable device. 
     In some embodiments, the first implantable device and the implantable lead are integrated. 
     In some embodiments, the implantable lead is fixedly attached to the first implantable device during a manufacturing process. 
     In some embodiments, the first implantable device is operably attached to the one or more stimulation elements via one or more wires. 
     In some embodiments, the at least one contact of the implantable lead comprises an insulating material. The insulating material can comprise a passivation layer applied to the at least one contact. The insulating material can comprise an insulating sleeve that surrounds the at least one contact. 
     The insulating material can extend from a most proximal contact to a most distal contact of the implantable lead. The insulating material can be configured to be removed from the at least one contact. The insulating material can be removed via a peeling process. 
     In some embodiments, the first implantable device and the implantable lead are operably attached via a connector. 
     In some embodiments, the lead removal tool comprises an opening, and the opening is configured to slidingly receive the first implantable device. The opening can comprise one or more projections, and the one or more projections can be configured to engage the implantable lead. The one or more projections can be configured to engage a proximal portion of the implantable lead. The one or more projections can be configured to engage the implantable lead at pre-determined location, and the pre-determined location can comprise a marker positioned on the implantable lead. The marker can be positioned at weakened portion of the implantable lead. The one or more projections can be configured to travel inward and frictionally engage the implantable lead in response to an external force. The one or more projections can cause a break in the implantable lead, and the implantable lead can be separated from the first implantable device. 
     In some embodiments, the second stimulation device can slidingly receive and operably engage the at least one contact of the implantable lead. 
     In some embodiments, the apparatus further comprises a lead attachment assembly. The lead attachment assembly can comprise an attachment mechanism configured to attach an implantable lead to a stimulation device. The attachment mechanism can comprise a base portion comprising one or more contacts operably connected to a conduit and one or more hinged portions. The one or more hinged portions can comprise a first recess configured to slidingly receive at least a portion of the implantable lead. The one or more contacts of the base portion can be configured to extend into the first recess and operably connect to one or more contacts of the implantable lead. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other objects, features and advantages of embodiments of the present inventive concepts will be apparent from the more particular description of preferred embodiments, as illustrated in the accompanying drawings in which like reference characters refer to the same or like elements. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the preferred embodiments. 
         FIG. 1  is a schematic view of a medical apparatus comprising an external system and two implantable systems, consistent with the present inventive concepts. 
         FIG. 1A  is a schematic view of an implantable device comprising an extending conduit for attachment to a lead, consistent with the present inventive concepts. 
         FIG. 1B  is a schematic view of an implantable device comprising an extending conduit for attachment to a lead and a contamination-limiting fitting, consistent with the present inventive concepts. 
         FIG. 1C  is a schematic view of two implantable devices, the first implantable device comprising a pre-attached lead, the lead comprising a removable portion, consistent with the present inventive concepts. 
         FIG. 2  is a flow chart of a method of providing stimulation for an initial trial period, and a subsequent therapy period, consistent with the present inventive concepts. 
         FIG. 3  is a perspective view of an apparatus comprising a temporary implantable device and an attachable lead for use in a trialing period, consistent with the present inventive concepts. 
         FIGS. 4A-B  are top views of an apparatus comprising a temporary implantable device and an attachment lead for use in a trialing period, consistent with the present inventive concepts. 
         FIGS. 5A-B  are top views of an apparatus comprising a temporary implantable device and an attachment lead for use in a trialing period, consistent with the present inventive concepts. 
         FIGS. 6A-C  are a side view, a sectional view, and a perspective view, respectively, of an attachment port of an implantable device, consistent with the present inventive concepts. 
         FIGS. 7A-C  are a side sectional view, a sectional view, and a perspective view, respectively, of an attachment port of an implantable device consistent with the present inventive concepts. 
         FIGS. 8A-C  are a side view, a sectional view, and a perspective view, respectively, of an attachment port of an implantable device, consistent with the present inventive concepts. 
         FIG. 9A-B  are a side sectional view, and an end view, respectively, of an implantable device, consistent with the present inventive concepts. 
         FIG. 10A-B  are perspective views of an implantable device prior to and after attachment to a lead, respectively, the implantable device comprising a rollable construction for surrounding the lead, consistent with the present inventive concepts. 
         FIGS. 11A-D  are perspective views of various embodiments of a distal portion of a stimulation lead, consistent with the present inventive concepts. 
         FIGS. 12A-C  are side views of various embodiments of a proximal portion of a stimulation lead, consistent with the present inventive concepts. 
         FIG. 13  is a flow chart of a method of providing stimulation during a trailing procedure, consistent with the present inventive concepts. 
         FIGS. 14A-D  are side views of an implantable system comprising a short-term (temporary) implantable device with an integrated lead, and a lead removal tool, consistent with the present inventive concepts. 
         FIGS. 15A-E  a perspective view of a stimulator and a lead attachment assembly, and various close-up views of an attachment mechanism of the attachment assembly, consistent with the present inventive concepts. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting of the inventive concepts. Furthermore, embodiments of the present inventive concepts may include several novel features, no single one of which is solely responsible for its desirable attributes or which is essential to practicing an inventive concept described herein. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. 
     It will be further understood that the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     It will be understood that, although the terms first, second, third etc. may be used herein to describe various limitations, elements, components, regions, layers, and/or sections, these limitations, elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are only used to distinguish one limitation, element, component, region, layer or section from another limitation, element, component, region, layer or section. Thus, a first limitation, element, component, region, layer or section discussed below could be termed a second limitation, element, component, region, layer or section without departing from the teachings of the present application. 
     It will be further understood that when an element is referred to as being “on”, “attached”, “connected” or “coupled” to another element, it can be directly on or above, or connected or coupled to, the other element, or one or more intervening elements can be present. In contrast, when an element is referred to as being “directly on”, “directly attached”, “directly connected” or “directly coupled” to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g. “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). A first component (e.g. a device, assembly, housing or other component) can be “attached”, “connected” or “coupled” to another component via a connecting filament (as defined below). In some embodiments, an assembly comprising multiple components connected by one or more connecting filaments is created during a manufacturing process (e.g. pre-connected at the time of an implantation procedure of the system of the present inventive concepts). Alternatively or additionally, a connecting filament can comprise one or more connectors (e.g. a connectorized filament comprising a connector on one or both ends), and a similar assembly can be created by a user (e.g. a clinician) operably attaching the one or more connectors of the connecting filament to one or more mating connectors of one or more components of the assembly. 
     It will be further understood that when a first element is referred to as being “in”, “on” and/or “within” a second element, the first element can be positioned: within an internal space of the second element, within a portion of the second element (e.g. within a wall of the second element); positioned on an external and/or internal surface of the second element; and combinations of one or more of these. 
     Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like may be used to describe an element and/or feature&#39;s relationship to another element(s) and/or feature(s) as, for example, illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use and/or operation in addition to the orientation depicted in the figures. For example, if the device in a figure is turned over, elements described as “below” and/or “beneath” other elements or features would then be oriented “above” the other elements or features. The device can be otherwise oriented (e.g. rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     The term “and/or” where used herein is to be taken as specific disclosure of each of the two specified features or components with or without the other. For example “A and/or B” is to be taken as specific disclosure of each of (i) A, (ii) B and (iii) A and B, just as if each is set out individually herein. 
     The term “diameter” where used herein to describe a non-circular geometry is to be taken as the diameter of a hypothetical circle approximating the geometry being described. For example, when describing a cross section, such as the cross section of a component, the term “diameter” shall be taken to represent the diameter of a hypothetical circle with the same cross sectional area as the cross section of the component being described. 
     The terms “major axis” and “minor axis” of a component where used herein are the length and diameter, respectively, of the smallest volume hypothetical cylinder which can completely surround the component. 
     The term “functional element” where used herein, is the be taken to include a component comprising one, two or more of: a sensor; a transducer; an electrode; an energy delivery element; an agent delivery element; a magnetic field generating transducer; and combinations of one or more of these. In some embodiments, a functional element comprises a transducer selected from the group consisting of: light delivery element; light emitting diode; wireless transmitter; Bluetooth device; mechanical transducer; piezoelectric transducer; pressure transducer; temperature transducer; humidity transducer; vibrational transducer; audio transducer; speaker; and combinations of one or more of these. In some embodiments, a functional element comprises a needle, a catheter (e.g. a distal portion of a catheter), an iontophoretic element or a porous membrane, such as an agent delivery element configured to deliver one or more agents. In some embodiments, a functional element comprises one or more sensors selected from the group consisting of: electrode; sensor configured to record electrical activity of tissue; blood glucose sensor such as an optical blood glucose sensor; pressure sensor; blood pressure sensor; heart rate sensor; inflammation sensor; neural activity sensor; muscular activity sensor; pH sensor; strain gauge; accelerometer; gyroscope; GPS; respiration sensor; respiration rate sensor; temperature sensor; magnetic sensor; optical sensor; MEMs sensor; chemical sensor; hormone sensor; impedance sensor; tissue impedance sensor; body position sensor; body motion sensor; physical activity level sensor; perspiration sensor; patient hydration sensor; breath monitoring sensor; sleep monitoring sensor; food intake monitoring sensor; urine movement sensor; bowel movement sensor; tremor sensor; pain level sensor; orientation sensor; motion sensor; and combinations of one or more of these. 
     The term “transducer” where used herein is to be taken to include any component or combination of components that receives energy or any input, and produces an output. For example, a transducer can include an electrode that receives electrical energy, and distributes the electrical energy to tissue (e.g. based on the size of the electrode). In some configurations, a transducer converts an electrical signal into any output, such as light (e.g. a transducer comprising a light emitting diode or light bulb), sound (e.g. a transducer comprising a piezo crystal configured to deliver ultrasound energy), pressure, heat energy, cryogenic energy, chemical energy; mechanical energy (e.g. a transducer comprising a motor or a solenoid), magnetic energy, and/or a different electrical signal (e.g. a Bluetooth or other wireless communication element). Alternatively or additionally, a transducer can convert a physical quantity (e.g. variations in a physical quantity) into an electrical signal. A transducer can include any component that delivers energy and/or an agent to tissue, such as a transducer configured to deliver one or more of: electrical energy to tissue (e.g. a transducer comprising one or more electrodes); light energy to tissue (e.g. a transducer comprising a laser, light emitting diode and/or optical component such as a lens or prism); mechanical energy to tissue (e.g. a transducer comprising a tissue manipulating element); sound energy to tissue (e.g. a transducer comprising a piezo crystal); thermal energy to tissue (e.g. heat energy and/or cryogenic energy); chemical energy; electromagnetic energy; magnetic energy; and combinations of one or more of these. 
     The term “transmission signal” where used herein is to be taken to include any signal transmitted between two components, such as via a wired or wireless communication pathway. For example, a transmission signal can comprise a power and/or data signal wirelessly transmitted between a component external to the patient and one or more components implanted in the patient. A transmission signal can include one or more signals transmitted using body conduction. Alternatively or additionally, a transmission signal can comprise reflected energy, such as energy reflected from any power and/or data signal. 
     The term “data signal” where used herein is to be taken to include a transmission signal including at least data. For example, a data signal can comprise a transmission signal including data and sent between a component external to the patient and one or more components implanted in the patient. Alternatively, a data signal can comprise a transmission signal including data sent from an implanted component to one or more components external to the patient. A data signal can comprise a radiofrequency signal including data (e.g. a radiofrequency signal including both power and data) and/or a data signal sent using body conduction. 
     The term “implantable” where used herein is to be taken to define a component which is constructed and arranged to be fully or partially implanted in a patient&#39;s body and/or a component that has been fully or partially implanted in a patient. The term “external” where used herein is to be taken to define a component which is constructed and arranged to be positioned outside of the patient&#39;s body. 
     The terms “connection”, “connected”, “connecting” and the like, where used herein, are to be taken to include any type of connection between two or more components. The connection can include an operable connection which allows multiple connected components to operate together such as to transfer information, power and/or material (e.g. an agent to be delivered) between the components. An operable connection can include a physical connection, such as a physical connection including one or more wires, optical fibers, wave guides, tubes such as fluid transport tubes and/or linkages such as translatable rods or other mechanical linkages. Alternatively or additionally, an operable connection can include a non-physical or “wireless” connection, such as a wireless connection in which information and/or power is transmitted between components using electromagnetic energy. A connection can include a connection selected from the group consisting of: a wired connection; a wireless connection; an electrical connection; a mechanical connection; an optical connection; a sound propagating connection; a fluid connection; and combinations of one or more of these. 
     The term “connecting filament” where used herein is to be taken to define a filament connecting a first component to a second component. The connecting filament can include a connector on one or both ends, such as to allow a user to operably attach at least one end of the filament to a component. A connecting filament can comprise one or more elements selected from the group consisting of: wires; optical fibers; fluid transport tubes; mechanical linkages; wave guides; flexible circuits; and combinations of one or more of these. A connecting filament can comprise rigid filament, a flexible filament or it can comprise one or more flexible portions and one or more rigid portions. 
     The term “connectorized” where used herein is to be taken to refer to a filament, housing or other component that includes one or more connectors (e.g. clinician or other user-attachable connectors) for operably connecting that component to a mating connector (e.g. of the same or different component). 
     The terms “stimulation parameter”, “stimulation signal parameter” or “stimulation waveform parameter” where used herein can be taken to refer to one or more parameters of a stimulation waveform (also referred to as a stimulation signal). Applicable stimulation parameters of the present inventive concepts shall include but are not limited to: amplitude (e.g. amplitude of voltage and/or current); average amplitude; peak amplitude; frequency; average frequency; period; phase; polarity; pulse shape; a duty cycle parameter (e.g. frequency, pulse width, and/or off time); inter-pulse gap; polarity; burst-on period; burst-off period; inter-burst period; pulse train; train-on period; train-off period; inter-train period; drive impedance; duration of pulse and/or amplitude level; duration of stimulation waveform; repetition of stimulation waveform; an amplitude modulation parameter; a frequency modulation parameter; a burst parameter; a power spectral density parameter; an anode/cathode configuration parameter; amount of energy and/or power to be delivered; rate of energy and/or power delivery; time of energy delivery initiation; method of charge recovery; and combinations of one or more of these. A stimulation parameter can refer to a single stimulation pulse, multiple stimulation pulses, or a portion of a stimulation pulse. The term “amplitude” where used herein can refer to an instantaneous or continuous amplitude of one or more stimulation pulses (e.g. the instantaneous voltage level or current level of a pulse). The term “pulse” where used herein can refer to a period of time during which stimulation energy is relatively continuously being delivered. In some embodiments, stimulation energy delivered during a pulse comprises energy selected from the group consisting of: electrical energy; magnetic energy; electromagnetic energy; light energy; sound energy such as ultrasound energy; mechanical energy such as vibrational energy; thermal energy such as heat energy or cryogenic energy; chemical energy; and combinations of one or more of these. In some embodiments, stimulation energy comprises electrical energy and a pulse comprises a phase change in current and/or voltage. In these embodiments, an inter-phase gap can be present within a single pulse. The term “quiescent period” where used herein can refer to a period of time during which zero energy or minimal energy is delivered (e.g. insufficient energy to elicit an action potential and/or other neuronal response). The term “inter-pulse gap” where used herein can refer to a quiescent period between the end of one pulse to the onset of the next (sequential) pulse. The terms “pulse train” or “train” where used herein can refer to a series of pulses. The terms “burst”, “burst of pulses” or “burst stimulation” where used herein can refer to a series of pulse trains, each separated by a quiescent period. The term “train-on period” where used herein can refer to a period of time from the beginning of the first pulse to the end of the last pulse of a single train. The term “train-off period” where used herein can refer to a quiescent period between the end of one train and the beginning of the next train. The term “burst-on period” where used herein can refer to a period of time from the beginning of the first pulse of the first train to the end of the last pulse of the last train of a single burst. The term “burst-off period” where used herein can refer to a quiescent period between the end of one burst and the beginning of the next burst. The term “inter-train period” where used herein can refer to a quiescent period between the end of one train and the beginning of the next train. The term “inter-burst period” where used herein can refer to a quiescent period between the end of one burst and the beginning of the next burst. The term “train envelope” where used herein can refer to a curve outlining the amplitude extremes of a series of pulses in a train. The term “burst envelope” where used herein can refer to a curve outlining the amplitude extremes of a series of pulses in a burst. The term “train ramp duration” where used herein can refer to the time from the onset of a train until its train envelope reaches a desired target magnitude. The term “burst ramp duration” where used herein can refer to the time from the onset of a burst until its burst envelope reaches a desired target magnitude. 
     It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. For example, it will be appreciated that all features set out in any of the claims (whether independent or dependent) can be combined in any given way. 
     The present inventive concepts include a medical apparatus and clinical methods for treating a patient, such as to treat pain. The patient can comprise a human or other mammalian patient. The medical apparatus can comprise a stimulation apparatus. The medical apparatus can comprise an implantable system and an external system. The implantable system can comprise one or more similar and/or dissimilar implantable devices. In some embodiments, the implantable system comprises a first implantable device that delivers stimulation energy via energy received wirelessly from one or more external devices, and a second implantable device that delivers stimulation energy via an integral (e.g. implanted) battery. In these embodiments, the first implantable device can be configured to deliver stimulation energy during a limited period of time (e.g. a trial period in which stimulation settings are determined and/or acceptability of the apparatus is determined), and the second implantable device can be configured to deliver stimulation energy for a prolonged period of time in which long-term stimulation therapy is provided to a patient. In these embodiments, a single implantable lead comprising one or more stimulation energy delivery elements (e.g. electrodes) can be connected to the first implantable device and then the second implantable device. In some embodiments, a first implantable device can be configured to remain implanted in the patient for a limited period of time, such as to reduce cost of manufacture, and a second implantable device is configured for a longer implant life. The first implantable device can be used in a trialing procedure in which the stimulation apparatus is assessed for acceptable use (e.g. by the patient and/or clinician) and/or one or more stimulation settings are optimized or otherwise determined. 
     Each implantable device can comprise one or more implantable antennas configured to receive power and/or data. In some embodiments, a first implantable device receives power and data, and a second implantable device receives data (e.g. without receiving power). Each implantable device can comprise an implantable receiver configured to receive the power and/or data from the one or more implantable antennas. Each implantable device can comprise one or more implantable functional elements. An implantable functional element can be configured to interface with the patient (e.g. interface with tissue of the patient or interface with any patient location). Alternatively or additionally, an implantable functional element can interface with a portion of an implantable device (e.g. to measure an implantable device parameter). In some embodiments, the one or more implantable functional elements can comprise one or more transducers, electrodes, and/or other elements configured to deliver energy to tissue. Alternatively or additionally, the one or more implantable functional elements can comprise one or more sensors, such as a sensor configured to record a physiologic parameter of the patient. In some embodiments, one or more implantable functional elements are configured to record device information and/or patient information (e.g. patient physiologic or patient environment information). 
     Each implantable device can comprise an implantable controller configured to control (e.g. modulate power to, send a signal to and/or receive a signal from) the one or more implantable functional elements. In some embodiments, an implantable controller of a first implantable device is configured to control one or more other implantable devices. Each implantable device can comprise an implantable energy storage assembly (e.g. a battery and/or a capacitor) configured to provide power to the implantable controller (e.g. a controller comprising a stimulation waveform generator), the implantable receiver and/or the one or more implantable functional elements. In some embodiments, an implantable energy storage assembly is further configured to provide power to an assembly that transmits signals via the implantable antenna (e.g. when the implantable device is further configured to transmit data to one or more external devices). Each implantable device can comprise an implantable housing surrounding the implantable controller and the implantable receiver. In some embodiments, one or more implantable antennas are positioned within the implantable housing. Alternatively or additionally, one or more implantable antennas and/or implantable functional elements can be tethered (e.g. electrically tethered) to the implantable housing. In some embodiments, one or more implantable functional elements are positioned on an implantable lead, such as a flexible lead mechanically fixed or attachable to the implantable housing and operably connected (e.g. electrically, fluidly, optically, and/or mechanically) to one or more components internal to the implantable housing. The implantable lead can be inserted (e.g. tunneled) through tissue of the patient, such that its one or more functional elements are positioned proximate tissue to be treated and/or positioned at an area in which data is to be recorded. In some embodiments, the implantable lead is configured to operably attach to and/or detach from, multiple implantable devices. 
     The external system of the medical apparatus of the present inventive concepts can comprise one or more similar and/or dissimilar external devices. Each external device can comprise one or more external antennas configured to transmit power and/or data to one or more implanted components of the implantable system. Each external device can comprise an external transmitter configured to drive the one or more external antennas. Each external device can comprise an external power supply configured to provide power to at least the external transmitter. Each external device can comprise an external programmer configured to control the external transmitter and/or an implantable device (e.g. when an external power transmitter is not included in the apparatus or otherwise not present during use). Each external device can comprise an external housing that surrounds at least the external transmitter. In some embodiments, the external housing surrounds the one or more external antennas, the external power supply and/or the external programmer. 
     The external programmer can comprise a discrete controller separate from the one or more external devices, and/or a controller integrated into one or more external devices. The external programmer can comprise a user interface, such as a user interface configured to set and/or modify one or more treatment and/or data recording settings of the medical apparatus of the present inventive concepts. In some embodiments, the external programmer is configured to provide control signals to one or more external devices (e.g. one or more external devices that provide at least power to a first implantable device), and to provide control signals to an implantable device (e.g. a second implantable device that does not receive power from an external device). In some embodiments, the external programmer can be configured to collect and/or diagnose recorded patient information, such as to provide the information and/or diagnosis to a clinician of the patient, to a patient family member and/or to the patient themselves. The collected information and/or diagnosis can be used to adjust treatment or other operating parameters of the medical apparatus. 
     In some embodiments, a medical apparatus comprises a stimulation apparatus for activating, blocking, affecting or otherwise stimulating (hereinafter “stimulate” or “stimulating”) tissue of a patient, such as nerve tissue or nerve root tissue (hereinafter “nerve”, “nerves”, “nerve tissue” or “nervous system tissue”). The stimulation apparatus comprises an external system configured to transmit power, and an implanted system comprising at least one implantable device configured to receive the power from the external system and to deliver stimulation energy to tissue. The implantable system can further comprise one or more additional implantable devices that do not receive power from the external system (e.g. implantable devices that have an internal battery or other power source that provides the stimulation energy). The delivered stimulation energy can comprise one or more stimulation waveforms, such as a stimulation waveform configured to enhance treatment of pain while minimizing undesired effects. The stimulation signal (also referred to as “stimulation energy” herein) delivered by the implanted system can be independent of the power received from the external system, such as to be independent of one or more of the position of one or more components of the external system; the changing position of one or more components of the external system; the frequency of the power received from the external system; the amplitude of the power received from the external system; changes in amplitude of the power received from the external system; duty cycle of the power received from the external system; envelope of the power received from the external system; and combinations of one or more of these. 
     Referring now to  FIG. 1 , a schematic view of a stimulation apparatus for providing a therapy to a patient is illustrated, consistent with the present inventive concepts. Apparatus  10  comprises implantable system  20  and external system  50 . External system  50  transmits transmission signals to one or more components of implantable system  20 . These transmission signals can comprise power and/or data. Implantable system  20  comprises implantable device  200  which is configured to be implanted beneath the skin of a patient. In some embodiments, implantable system  20  comprises multiple similar or dissimilar implantable devices  200  (singly or collectively implantable device  200 ), such as is described in applicant&#39;s co-pending application International PCT Patent Application Serial Number PCT/US2017/017978, titled “Apparatus with Enhanced Stimulation Waveforms”, filed Feb. 15, 2017, the content of which is incorporated herein in its entirety for all purposes. Each implantable device  200  can be configured to receive power and data from a transmission signal transmitted by external system  50 , such as when stimulation energy delivered to the patient (e.g. to nerve or other tissue of the patient) by implantable device  200  is provided via wireless transmissions signals from external system  50 . In some embodiments, implantable system  20  further comprises a second implantable device, implantable device  800  shown, also configured to be implanted beneath the skin of the patient. In these embodiments, implantable device  800  can provide one or more implantable devices that deliver stimulation energy to the patient without receiving power from external system  50 , such as when power is (primarily) provided from a power source internal to implantable device  800  (e.g. energy storage assembly  870  shown or other energy storage element of implantable device  800 ). While not receiving power, implantable device  800  can receive data (e.g. stimulation parameters or other programming data) from external system  50 . 
     Implantable system  20  can comprise one or more implantable leads, such as implantable lead  265  shown. Lead  265  comprises one or more stimulation elements (e.g. one or more electrodes or other energy delivering elements as described herein), stimulation element  260  (three shown in  FIG. 1 ). Alternatively or additionally, one or more stimulation elements  260  can be positioned on housing  210  of implantable device  200  and/or housing  810  of implantable device  800 , for example when current is delivered in a monopolar mode (e.g. current delivered between a stimulation element  260  on lead  265  and a stimulation element  260  on housing  210  and/or  810 ). Implantable device  200  is configured to operably connect (e.g. electrically, optically, acoustically and/or otherwise operably connect) to lead  265 , via its implantable connector, attachment port  290 , such as via a connection performed by a clinician during a surgical procedure in which one or more components of implantable system  20  are implanted in the patient. Implantable device  800  is also configured to operably connect to lead  265  (e.g. the same lead  265  or a newly implanted lead  265 ), via its implantable connector, attachment port  890 . Attachment ports  290  and  890  can be of similar or dissimilar construction. For example, attachment port  290  can be constructed and arranged to provide a contamination-preventing seal with lead  265  for a limited time period (e.g. less than 3 months), while attachment port  890  can be constructed and arranged to provide a contamination-preventing seal with lead  265  for an extended time period (e.g. at least 3 months, at least 1 year, or at least 2 years). In some embodiments, implantable device  200  is configured to disconnect from lead  265  (e.g. in a second clinical procedure performed after the implantable device  200  implantation procedure), such that implantable device  800  can subsequently be connected to the same lead  265 , such as is described herebelow in reference to  FIG. 2 . In these embodiments, implantable device  200  can be configured to be implanted in the patient to conduct a trial procedure via lead  265  (e.g. as described herebelow in reference to  FIG. 2 ) for a trial period, after which implantable device  800  is implanted to provide stimulation therapy to the patient for a therapy period, such as via the same, previously implanted lead  265 . 
     External system  50  can comprise an external device  500 , which includes housing  510 . In some embodiments, external system  50  comprises multiple external devices  500  (singly or collectively external device  500 ), also as is described in applicant&#39;s co-pending application International PCT Patent Application Serial Number PCT/US2017/017978, titled “Apparatus with Enhanced Stimulation Waveforms”, filed Feb. 15, 2017. Each external device  500  can be configured to transmit transmission signals that send power and/or data to one or more components of implantable system  20 , such as implantable device  200 . Alternatively or additionally, external system  50  can comprise external programmer, programmer  550 , which can comprise a user interface, such as user interface  555 . Programmer  550  can be configured to transmit transmission signals that send data to: one or more external devices  500 , one or more implantable devices  200 , and/or one or more implantable devices  800 , such as to adjust the settings of or otherwise control these components of apparatus  10 . External programmer  550  can comprise housing (housing  551 ), a transmitting element (transmitter  553 ), a battery or other power supply (power supply  557 ), and one or more antennas (antenna  540   a ). 
     Apparatus  10  can be configured to stimulate tissue (e.g. stimulate nerve tissue such as tissue of the central nervous system or tissue of the peripheral nervous system, such as to neuromodulate nerve tissue), such as by having one or more implantable devices  200  and/or implantable devices  800  deliver energy to one or more tissue locations. In some embodiments, one or more implantable devices  200  deliver energy (e.g. continuously or intermittently) to the patient while simultaneously, or relatively simultaneously (e.g. power received from external system  50  within 60 seconds, within 5 minutes and/or within 15 minutes of stimulation delivery, “simultaneously” herein) receiving power from one or more external devices  500 . In some embodiments, one or more implantable devices  800  deliver energy (e.g. continuously or intermittently) to the patient, where the energy is provided by an internal power source (e.g. a battery and/or capacitor, such as energy storage assembly  870  shown) without receiving externally supplied power. For example, implantable device  800  may not receive power from any external device for a time period of at least 1 hour, at least 1 day, at least 1 month or at least 1 year, while delivering stimulation energy during those same time periods. During those time periods of no energy being provided from an external source, one or more stimulation parameters of implantable device  800  can be varied during those periods, such as a variation based on data sent by programmer  550 , an external device  500  and/or other external component of apparatus  10 . 
     In some embodiments, apparatus  10  is further configured as a patient diagnostic apparatus, such as by having one or more implantable devices  200 , one or more implantable devices  800 , and/or one or more external devices  500  record a patient parameter (e.g. a patient physiologic parameter) from one or more tissue locations. In some embodiments, during its use, one or more implantable devices  200  at least receives power from one or more external devices  500  (e.g. with or without also receiving data). 
     Alternatively or additionally, apparatus  10  can be configured as a patient information recording apparatus, such as by having one or more implantable devices  200 , one or more implantable devices  800 , and/or one or more external devices  500  record patient information (e.g. patient physiologic information and/or patient environment information). In some embodiments, one or more implantable devices  200 , one or more implantable devices  800 , and/or one or more external devices  500  further collect information (e.g. status information or configuration settings) of one or more of the components of apparatus  10 . 
     In some embodiments, apparatus  10  is configured to deliver stimulation energy to tissue to treat pain. In particular, apparatus  10  can be configured to deliver stimulation energy to tissue of the spinal cord and/or tissue associated with the spinal cord (“tissue of the spinal cord”, “spinal cord tissue” or “spinal cord” herein), the tissue including roots, dorsal root, dorsal root ganglia, spinal nerves, ganglia, and/or other nerve tissue. The delivered energy can comprise energy selected from the group consisting of: electrical energy; magnetic energy; electromagnetic energy; light energy such as infrared light energy, visible light energy, and/or ultraviolet light energy; mechanical energy; thermal energy such as heat energy and/or cryogenic energy; sound energy such as ultrasonic sound energy (e.g. high intensity focused ultrasound and/or low intensity focused ultrasound) and/or subsonic sound energy; chemical energy; and combinations of one or more of these. In some embodiments, apparatus  10  is configured to deliver energy to tissue in a form selected from the group consisting of: electrical energy such as by providing a controlled (e.g. constant or otherwise controlled) electrical current and/or voltage to tissue; magnetic energy (e.g. magnetic field energy) such as by applying controlled current or voltage to a coil or other magnetic field generating element positioned proximate tissue; and/or electromagnetic energy such as by providing both current to tissue and a magnetic field to tissue. The coil or other magnetic field generating element can surround (e.g. at least partially surround) the target nerve and/or it can be incorporated as part of an anchoring system to the target tissue. Alternatively, or additionally, the magnetic energy can be applied externally and focused to specific target tissue via an implant comprising a coil and/or ferromagnetic materials. In some embodiments, the magnetic energy is configured to induce the application of mechanical energy. Delivered energy can be supplied in one or more stimulation waveforms, each waveform comprising one or more pulses of energy, as described in detail herebelow. 
     In some embodiments, apparatus  10  is configured as a stimulation apparatus in which external system  50  transmits a power signal to one or more implantable devices  200 , and the one or more implantable devices  200  delivers stimulation energy to tissue with a stimulation signal (also referred to as a stimulation waveform), with the power signal and the stimulation signal having one or more different characteristics. The power signal can further be modulated with data (e.g. configuration or other data to be sent to one or more implantable devices  200 ). In these embodiments, the characteristics of the stimulation signal delivered (e.g. amplitude, frequency, duty cycle, and/or pulse width), can be independent (e.g. partially or completely independent) of the characteristics of the power signal transmission (e.g. amplitude, frequency, phase, envelope, duty cycle, and/or modulation). For example, the frequency and modulation of the power signal can change without affecting the stimulation signal, or the stimulation signal can be changed (e.g. via programmer  550 ), without requiring the power signal to change. In some embodiments, implantable system  20  can be configured to rectify the power signal, and produce a stimulation waveform with entirely different characteristics (e.g. amplitude, frequency, and/or duty cycle) from the rectified power signal. Each implantable device  200  can comprise an oscillator and/or controller configured to produce the stimulation signal. In some embodiments, one or more implantable devices  200  is configured to perform frequency multiplication, in which multiple signals are multiplexed, mixed, added, and/or combined in other ways to produce a broadband stimulation signal. 
     In some embodiments, apparatus  10  is configured such that external system  50  transmits data (e.g. data and power) to one or more implantable devices  200 , and each implantable device  200  recovers (e.g. decodes, demodulates or otherwise recovers) the transmitted data without synchronizing to the carrier and/or data symbol rate of the transmitted signal from external system  50 . In some embodiments, the transmitted signal comprises a power signal, and a clock and/or data is recovered without synchronizing to the power signal. In some embodiments, the transmitted signal comprises a clock and/or data signal, and a clock and/or data is recovered without synchronizing to the transmitted clock and/or data signal. In some embodiments, the recovered signal comprises a clock and/or data and a clock and/or data is recovered from the transmission signal without synchronizing to the recovered clock and/or data. Avoiding synchronization reduces power consumption of each implantable device  200 , such as by obviating the need for (and avoiding the power consumed by) a frequency locked loop (FLL); phase locked loop (PLL); high frequency clock; and/or crystal oscillator needed to perform the synchronization. Avoiding these components can also be correlated to reduced package size of each implantable device  200  (e.g. avoidance of a relatively large sized crystal oscillator). Asynchronous data transfer between external system  50  and each implantable device  200  is also advantageous as it relates to: increased communication data rate; power transfer efficiency; operation with more than one implantable device  200 ; and combinations of one or more of these. In some embodiments, one or more components of apparatus  10  are of similar construction and arrangement as similar components described in U.S. patent application Ser. No. 13/591,188, titled “Method of Making and Using an Apparatus for a Locomotive Micro-Implant using Active Electromagnetic Propulsion”, filed Aug. 21, 2012, the content of which is incorporated herein by reference in its entirety for all purposes. In some embodiments, external system  50  and implantable system  20  provide asynchronous data transfer or are otherwise configured as described in U.S. patent application Ser. No. 13/734,772, titled “Method and Apparatus for Efficient Communication with Implantable Devices”, filed Jan. 4, 2013, the content of which is incorporated herein by reference in its entirety for all purposes. 
     Apparatus  10  can be configured to treat pain, such as back and/or leg pain treated by stimulating dorsal root ganglia, and/or other nerves or locations of the spinal cord or other nervous system locations. In some embodiments, apparatus  10  is configured to treat a type of pain selected from the group consisting of back pain; joint pain; neuropathic pain; tennis elbow; muscle pain; shoulder pain; chronic, intractable pain of the back and/or lower limbs including unilateral or bilateral pain; neuropathic groin pain; perineal pain; phantom limb pain; complex regional pain syndrome; failed back surgery syndrome; cluster headaches; migraines; inflammatory pain; arthritis; abdominal pain; pelvic pain; and combinations of one or more of these. In some embodiments, apparatus  10  is configured to treat a patient disease or disorder selected from the group consisting of chronic pain; acute pain; migraine; cluster headaches; urge incontinence; pelvic dysfunction such as overactive bladder; fecal incontinence; bowel disorders; tremor; obsessive compulsive disorder; depression; epilepsy; inflammation; tinnitus; high blood pressure; heart failure; carpal tunnel syndrome; sleep apnea; obstructive sleep apnea; dystonia; interstitial cystitis; gastroparesis; obesity; mobility issues; arrhythmia; rheumatoid arthritis; dementia; Alzheimer&#39;s disease; eating disorder; addiction; traumatic brain injury; chronic angina; congestive heart failure; muscle atrophy; inadequate bone growth; post-laminectomy pain; liver disease; Crohn&#39;s disease; irritable bowel syndrome; erectile dysfunction; kidney disease; and combinations of one or more of these. 
     Apparatus  10  can be configured to treat heart disease, such as heart failure of a patient. In these embodiments, stimulation of the spinal cord can be performed. In canine and porcine animals with failing hearts, spinal cord stimulation has been shown to reverse left ventricular dilation and improve cardiac function, while suppressing the prevalence of cardiac arrhythmias. In canines, coronary artery occlusion has been associated with increased intracardiac nerve firing, and stimulation at spinal segment T1 has been shown to suppress that nerve firing. Stimulation via apparatus  10  at one or more spinal cord locations can be used to suppress undesired cardiac nerve firing in humans and other mammalian patients. In some embodiments, stimulation via apparatus  10  at multiple spinal cord locations is used to enhance a cardiac treatment. For example, one or more stimulation elements  260  of lead  265  can be implanted at one or more spinal cord locations. In some embodiments, stimulation elements  260  comprise two or more stimulation elements (e.g. electrodes) that span multiple vertebra of the spinal column (e.g. multiple stimulation elements that span at least T8 to T9 and/or T-9 to T-10). Lead  265  can receive stimulation energy for a first time period from a connected implantable device  200 , and subsequently for a second time period from a connected implantable device  800 . One or more stimulation signals can be delivered to spinal cord tissue, such as to treat heart failure or other cardiac disease or disorder. In some embodiments, one or more stimulation elements  260  are configured to deliver energy (e.g. electrical energy) to tissue to treat heart failure, such as tissue selected from the group consisting of spinal canal; nerves in the spinal canal; nerves in the epidural space; peripheral nerves; posterior spinal nerve root; dorsal root; dorsal root ganglion; pre-ganglionic tissue on posterior spinal nerve root; post-ganglionic tissue on posterior nerve root; dorsal ramus; grey ramus communicans; white ramus communicans; ventral ramus; and combinations of one or more of these. In some embodiments, one or more functional elements of apparatus  10  (e.g. one or more stimulation elements  260  of implantable system  20 ) are used to record a patient parameter, such as a patient heart or spine parameter, and the information recorded is used to adjust the delivered stimulation signals. The at least one heart parameter can comprise a parameter selected from the group consisting of: EKG; blood oxygen; blood pressure; heart rate; ejection fraction; wedge pressure; cardiac output; and combinations of one or more of these. 
     Apparatus  10  can be configured to pace and/or defibrillate the heart of a patient. One or more stimulation elements  260  can be positioned proximate cardiac tissue and deliver a stimulation signal as described herein (e.g. based on power and/or data received by implantable system  20  from external system  50  or via an internal battery, such as energy storage assembly  870  of implantable device  800 ). The stimulation signal can be used to pace, defibrillate and/or otherwise stimulate the heart. Alternatively or additionally, apparatus  10  can be configured to record cardiac activity (e.g. by recording EKG, blood oxygen, blood pressure, heart rate, ejection fraction, wedge pressure, cardiac output, lung impedance and/or other properties or functions of the cardiovascular system), such as to determine an onset of cardiac activity dysfunction or other undesired cardiac state. In some embodiments, apparatus  10  is configured to both record cardiac or other information and deliver a stimulation signal to cardiac tissue (e.g. stimulation varied or otherwise based on the recorded information). For example, apparatus  10  can be configured such that external system  50  transmits power and/or data to implantable system  20  while lead  265  is attached to an implantable device  200 , and transmits data (only) to implantable system  20  while lead  265  is attached to implantable device  800 . Implantable system  20  monitors cardiac activity, and upon detection of an undesired cardiovascular state, implantable system  20  delivers a pacing and/or defibrillation signal to the tissue that is adjacent to one or more stimulation elements  260  configured to deliver a cardiac stimulation signal. 
     External device  500  can comprise a wrist band, a wrist watch or an arm band configuration such as when the implantable device  200  is positioned in subcutaneous tissue proximate the patient&#39;s wrist or upper arm. The external device  500  can comprise a leg, knee or ankle band configuration, such as when one or more implantable devices  200  are positioned in subcutaneous tissue proximate the patient&#39;s thigh, knee and/or ankle. In some embodiments, external device  500  comprises a band or other attachment device for positioning about the thorax, neck, groin and/or head of the patient. Power and/or data can be sent to the implantable device  200  from the external device  500 , and data (e.g. blood glucose data) can be sent to external device  500  (or another component of external system  50 ) by implantable device  200 , such as using a communication configuration known to those of skill in the art. Various closed loop sensing and stimulation delivery combinations and configurations should be considered within the spirit and scope of the present inventive concepts, including but not limited to: sensing a blood parameter such as white blood cell count and adjusting energy delivery; sensing a hormone level and adjusting energy delivery; sensing blood pressure and adjusting energy delivery; sensing neural activity and adjusting energy delivery, such as for treating epilepsy; and combinations of one or more of these. 
     External system  50  can be configured to transmit power and/or data (e.g. implantable device  200  configuration data) to one or more implantable devices  200  of implantable system  20 . External system  50  can be configured to transmit data (e.g. implantable device  800  configuration data) to one or more implantable devices  800  of implantable system  20 . Configuration data provided by external system  50  (e.g. via one or more antennas  540   a  of programmer  550  and/or one antennas  540   b  of one or more external devices  500 , as described herein) can include when to initiate stimulation delivery (e.g. energy delivery), when to stop stimulation delivery, and/or data related to the value or change to a value of one or more stimulation settings as described herein. The configuration data can include a sensing parameter, such as a sensing parameter selected from the group consisting of: initiation of sensor recording; cessation of sensor recording; frequency of sensor recording; resolution of sensor recording; thresholds of sensor recording; sampling frequency of sensor recording; dynamic range of sensor recording; initiation of calibration of sensor recording; and combinations of one or more of these. 
     External system  50  can comprise one or more external devices  500  and/or one or more programmers  550 . Programmer  550  can comprise one or more antennas  540   a . Each external device  500  can comprise one or more antennas  540   b . The one or more antennas  540   a  and/or  540   b  (generally antenna  540 ) can transmit power and/or data to one or more antennas  240  of each implantable device  200  and/or one or more antennas  840  of each implantable device  800 , such as when a single implantable device  200  and/or a single implantable device  800  comprises one or more antennas  240  and/or  840  respectively, or when multiple implantable devices  200  and/or  800  (singly or collectively implantable device  200 / 800 ) each comprise one or more antennas  240  and/or  840  (singly or collectively antenna  240 / 840 ), respectively. In some embodiments, one or more antennas  540  define a radiation footprint (e.g. a footprint defining a volume, such as a volume of tissue, in which electromagnetic transmissions radiated by antennas  540  can be properly received by antennas  240 / 840 ), such as is described in applicant&#39;s co-pending International PCT Patent Application Serial Number PCT/US2016/016888, titled “Medical Apparatus including an Implantable System and an External System”, filed Feb. 5, 2016; the content of which is incorporated herein by reference in its entirety for all purposes. 
     External system  50  transmits power and/or data with a transmission signal comprising at least one wavelength, λ. External system  50  and/or implantable system  20  can be configured such that the distance between an external antenna  540  transmitting the power and/or data and one or more implantable antennas  240 / 840  receiving the power and/or data transmission signal is equal to between 0.1λ and 10.0, such as between 0.2λ and 2.0λ. In some embodiments, one or more transmission signals are delivered at a frequency range between 10 MHz and 10.6 GHz, such as between 0.1 GHz and 10.6 GHz, between 10 MHz and 3.0 GHz, between 40 MHz and 1.5 GHz, or between 0.902 GHz and 0.928 GHz, or in a frequency range proximate to 40.68 MHz, proximate to 866 MHz, or approximately between 863 MHz and 870 MHz. 
     In addition to transmitting power and/or data to implantable system  20 , external system  50  can be further configured to provide information (e.g. patient information and/or apparatus  10  performance information) to one or more other devices of apparatus  10 , such as tool  60  shown in  FIG. 1  and described in detail herebelow. 
     One or more external devices  500  (singly or collectively external device  500 ) can be configured to transmit power and/or data (e.g. implantable system  20  configuration data) to one or more implantable devices  200 / 800 . In some embodiments, one or more external devices  500  are configured to transmit both power and data (e.g. simultaneously and/or sequentially) to one or more implantable devices  200 . In some embodiments, one or more external devices  500  are further configured to receive data from one or more implantable devices  200 / 800  (e.g. via data transmitted by one or more antennas  240 / 840 ). 
     Each external device  500  can comprise housing  510 , power supply  570 , a transmitter  530 , and/or one or more antennas  540   b , as described herein. 
     One or more housings  510  (singly or collectively housing  510 ) of each external device  500  can comprise one or more rigid and/or flexible materials which surround various components of external device  500  such as antenna  540   b , transmitter  530  and/or power supply  570 . In some embodiments, a single external device  500  comprises multiple discrete (i.e. separate) housings  510 , two or more of which can transfer data or other signals via a wired or wireless connection. In some embodiments, housing  510  comprises both a rigid material and a flexible material. In some embodiments, housing  510  comprises a material selected from the group consisting of: plastic; injection-molded plastic; an elastomer; metal; and combinations of one or more of these. In some embodiments, housing  510  comprises a shielded portion (e.g. shielded to prevent transmission of electromagnetic waves), and an unshielded portion, such as an unshielded portion surrounding antenna  540   b.    
     Housing  510  can comprise an adhesive element, not shown but such as an adhesive element configured to temporarily attach an external device  500  to the patient&#39;s skin. Housing  510  can be constructed and arranged to engage (e.g. fit in the pocket of) a patient attachment device, such as patient attachment device  70  described herebelow. 
     One or more antennas  540   a  and/or  540   b  (singly or collectively antenna  540 ) can each comprise one, two, three or more external antennas. Antenna  540  can comprise one or more polarizable antennas, such as one or more antennas with adjustable polarization. Antenna  540  can comprise an array of antennas, such as an array of antennas configured to: support beam shaping and/or focusing; allow adjustment of the amplitude and/or phase of the transmission signal; increase the radiation footprint; and combinations of one or more of these. An array of antennas  540  can be configured to be selectively activated, such as to improve coupling with one or more implanted antennas  240 / 840 , such as to adjust for movement of the array of the antennas  540  relative to the implanted antennas  240 / 840 . Antenna  540  can comprise an array of selectable conductors configured to adjust a radiation pattern and/or an electromagnetic field of a resultant antenna. Antenna  540  can comprise a surface and shield material positioned on the surface, such as when the shield material is positioned on the side facing away from the patient&#39;s skin. The shield material can comprise radio-absorptive shield material and/or radio-reflective shield material. One or more antennas  540  can be positioned in a housing (e.g. housing  510  or housing  551 ) that is otherwise void of other components (e.g. void of power supply  570  and transmitter  530 ), such as when an antenna  540  is positioned within a first housing  510  and communicates with components positioned in a second housing  510 . 
     In some embodiments, a spacer  511  is positioned between antenna  540   b  and the patient&#39;s skin, such as a spacer comprising a thickened portion of housing  510  or a discrete spacer  511  placed on a side of housing  510  (as shown) or on a side of antenna  540   b . Spacer  511  can comprise one or more materials that match the impedance of antenna  540   b  to the impedance of the patient&#39;s tissue. Spacer  511  can comprise a thickness of between 0.1 cm to 3 cm, such as a thickness between 0.2 cm and 1.5 cm. Spacer  511  can comprise materials which isolate heat (e.g. when spacer  511  comprises a thermally insulating material). Alternatively, or additionally, housing  510  can comprise a heat insulating and/or dissipating material. Spacer  511  can comprise a soft or otherwise compressible material (e.g. foam) for patient comfort. Spacer  511  can be inflatable, such as to control the separation distance of an external antenna  540   b  from the patient&#39;s skin. An inflatable spacer  511  can be compartmentalized into several sections with independently controlled air pressure or volume to adjust the separation distance of an external antenna  540  and the patient&#39;s skin and/or its angle (e.g. tilt) with respect to the tissue surface. 
     In some embodiments, antenna  540  comprises a multi-feed point antenna, such as a multi-feed point antenna configured to: support beam shaping and/or focusing; allow adjustment of amplitude and/or phase of a transmission signal; increase the radiation footprint; or combinations of one or more of these. 
     In some embodiments, antenna  540  comprises one or more antennas selected from the group consisting of: patch antenna; slot antenna; array of antennas; a loop antenna (e.g. a concentric loop antenna); antenna loaded with reactive elements; dipole antenna; polarizable antenna; selectable conductors that form an antenna; and combinations of one or more of these. 
     Antenna  540  can comprise a major axis between lcm and 10 cm, such as a major axis between 2 cm and 5 cm. Antenna  540  can be further configured to receive a signal, such as when an antenna  240 / 840  is configured to transmit data to an external device  500  and/or programmer  550 . Antenna  540  can be positioned on (e.g. fabricated onto) a substrate, such as a flexible printed circuit board or other printed circuit board (e.g. a single or multiple layer printed circuit board comprising electrical traces connecting components). 
     A single external antenna  540  can be configured to transmit power and/or data to multiple implantable devices  200 / 800  (e.g. each containing one or more antennas  240 / 840 ). In some embodiments, a single external device  500 , comprising one or more antennas  540   b , can be configured to transmit power and/or data to multiple implantable devices  200 . 
     One or more antennas  540  can comprise a multi-turn spiral loop antenna, such as a multi-turn spiral loop antenna configured to desensitize coupling sensitivity and/or boost input voltage. In some embodiments, one or more antennas  540  comprise multiple concentric loops with varied dimensions, such as concentric loops configured to desensitize coupling sensitivity. In these embodiments, the multiple concentric loops can be: connected in parallel and driven from the same feed point; driven from the same feed point and connected using one or more of a capacitor, inductor, varactor, and combinations of one or more of these; and/or driven from multiple feed points. 
     In some embodiments, one or more external devices  500  and/or programmer  550  comprise a first antenna  540  and a second antenna  540 . In these embodiments, the first antenna  540  can be similar or dissimilar to the second antenna  540 . In some embodiments, a first antenna  540  and a dissimilar second antenna  540  are positioned within a single external device  500  (e.g. within housing  510 ) and/or a single programmer  550  (e.g. within housing  551 ). In other embodiments, a first antenna  540  is positioned in a first external device  500 , and a dissimilar second antenna  540  is positioned in a second external device  500 . The similarity or dissimilarity of the antennas can be configured to enhance one or more design and/or performance parameters selected from the group consisting of: implantable device  200 / 800  operation depth; polarization; power efficiency; a radiation footprint; directional gain; beam shaping and/or focusing; sensitivity to implantable device  200 / 800  placement; patient comfort; patient usability; data transfer; and combinations of one or more of these. In some embodiments, the first antenna  540  can be optimized for a different design parameter than the second antenna  540 , and each antenna  540  can be activated independently or simultaneously to realize both benefits. In some embodiments, the first antenna  540  can be similar to the second antenna  540  and placed in an array to increase the radiation footprint or placed in different external locations to operate with multiple implantable devices  200 / 800  implanted at different sites. 
     In some embodiments, a first external antenna  540  and a second external antenna  540  transmit power and/or data to a single implantable antenna  240  or  840 . In some embodiments, a first antenna  540  and a second antenna  540  can transmit power and/or data to two or more antennas  240 / 840 , the transmissions occurring simultaneously or sequentially. In sequential power and/or data transfers, a first external device  500  comprising a first one or more antennas  540   b  can be replaced (e.g. swapped) with a second external device  500  comprising a second one or more antennas  540   b . Alternatively or additionally, sequential power and/or data transfer can be initiated by one or more of the following conditions: when the first external antenna  540  moves (e.g. moves relative to the implanted antenna  240 / 840 ); when a second external device  500  comprising a second antenna  540   b  is turned on or otherwise activated; when a second antenna  540  provides improved power and/or data transfer to the antenna  240 / 840  than is provided by a first antenna  540 ; and/or when power received from a first antenna  540  decreases (e.g. decreases below a threshold). In some embodiments, an antenna  240  receives power from a first antenna  540  and a second antenna  540 , but only receives data from the first antenna  540 . In some embodiments, a first antenna (e.g. an antenna  240 , an antenna  840 , or an antenna  540 ) is driven with a different carrier signal than a second antenna (e.g. an antenna  240 , an antenna  840 , or an antenna  540 ). The two carrier signals can comprise differences in amplitudes and/or relative phases as compared to each other. Each carrier signal can include a data transmission signal (e.g. data to be transmitted to an implantable device  200 / 800  from an external device  500  or to an external device  500  from an implantable device  200 / 800 ). 
     As described herein, one or more programmers  550  and/or external devices  500  can be configured to transmit data (e.g. configuration data) to one or more implantable devices  200 / 800 . In programmer  550 , antenna  540   a  transmits the data-based transmission signal produced by transmitter  553 . In external device  500 , antenna  540   b  transmits the data-based transmission signal produced by transmitter  530 . In some embodiments, a transmitter  553  and/or a transmitter  530  (singly or collectively transmitter  553 / 530 ) is configured to perform data modulation comprising amplitude shift keying with pulse width modulation. In these embodiments, the transmitter can be configured to perform multi-level amplitude shift keying. The amplitude shift-keying can be configured to provide adjustable-depth modulation between 0-100% depth, such as between 5-75% depth, or such as between 10-50% depth. In some embodiments, programmer  550  and/or one or more external devices  500  transmit data to one or more implantable devices  200 / 800  using time division multiple access (TDMA). In some embodiments, one or implantable devices  200 / 800  are independently addressable through unique identification (ID) codes. Alternatively or additionally, transmitters  553 / 530  can be configured to transmit one or more data signals with a bandwidth between 1 kHz and 100 MHz, between 0.1 MHz and 100 MHz, or between 1 MHz and 26 MHz. 
     One or more transmitters  553 / 530  can each comprise one or more external transmitters that drive one or more antennas  540 . In some embodiments, transmitter  553 / 530  comprises a transmitter that operates in a frequency range between 10 MHz and 10.6 GHz, such as a transmitter that operates in a frequency range between 0.1 GHz and 10.6 GHz, between 10 MHz and 3.0 GHz, between 40 MHz and 1.5 GHz, or between 0.902 GHz and 0.928 GHz, or in a frequency range proximate to 40.68 MHz, proximate to 866 MHz, or approximately between 863 MHz and 870 MHz. Transmitter  553 / 530  can comprise a transmitter that produces a transmission signal with a power level between 0.1 W and 4.0 W, such as a transmission signal with a power level between 0.1 W and 2.0 W or between 0.2 W and 1.0 W. 
     As described herein, one or more external devices  500  can be configured to transmit power to one or more implantable devices  200 , such as via a power transmission produced by transmitter  530  and sent to one or more antennas  540   b . One or more transmitters  530  can deliver power to one or more implantable devices  200  simultaneously or sequentially. In some embodiments, one or more transmitters  530  are configured to adjust the level of power transmitted to one or more implantable devices  200 / 800 , such as by adjusting one or more duty cycling parameters. In these embodiments, power transmitted can be adjusted to: set a power transfer based on a stimulation level produced by implantable system  20 ; prevent oversaturation; to reduce interference with implantable system  20  data transmissions (e.g. when one or more implantable devices  200 / 800  are further configured to transmit data to external system  50 ); set a power transfer based on charge information and/or discharge information related to an implantable device  200 / 800  (e.g. charge rate and/or discharge rate of an implantable energy storage assembly  270  and/or  870 ); and combinations of one or more of these. In some embodiments, implantable system  20  comprises a first receiver  230  (e.g. of a first implantable device  200 ) and a second receiver  230  (e.g. of a second implantable device  200 ). One or more transmitters  530  can be configured to transmit a first power transmission to the first receiver  230 , and a second power transmission to the second receiver  230 . The first power transmission and the second power transmission can be adjusted or otherwise be different, such as to prevent oversaturation. 
     In some embodiments, transmitter  553 / 530  (and/or another component of external system  50 ) is further configured as a receiver, such as to receive data from implantable system  20 . For example, a transmitter  553 / 530  can be configured to receive data via one or more antennas  240 / 840  of one or more implantable devices  200 / 800 . Data received can include patient information (e.g. patient physiologic information, patient environment information or other patient information) and/or information related to an implantable system  20  parameter (e.g. an implantable device  200 / 800  stimulation parameter and/or other configuration parameter as described herein). 
     In some embodiments, transmitter  553 / 530  comprises a first transmitter to transmit power and/or data to one implantable device  200  or  800 , and a second transmitter to transmit data to a different device. In these embodiments, a second transmitter of transmitter  553 / 530  can be configured to transmit data to tool  60  or another device such as: external device  500  (e.g. when the transmission emanates from transmitter  553  of programmer  550 ); programmer  550  (e.g. when the transmission emanates from transmitter  530  of external device  500 ); a cell phone; a computer; a tablet; a computer network such as the internet or a LAN; and combinations of one or more of these. In some embodiments, the second transmitter of transmitter  553 / 530  comprises a wireless transmitter; a Bluetooth transmitter; a cellular transmitter; and combinations of one or more of these. In some embodiments, a functional element  599  (e.g. functional element  599   a  of programmer  550  and/or functional element  599   b  of external device  500 ) comprises a transmitter such as a Bluetooth transmitter. 
     Each power supply  557  and/or  570  (singly or collectively power supply  557 / 570 ) can be operably attached to a transmitter  553 / 530 , and one or more other electrical components of programmer  550  or external device  500 , respectively. Power supply  557 / 570  can comprise a power supplying and/or energy storage element selected from the group consisting of: battery; replaceable battery (e.g. via a battery door of housing  551  or  510 , respectively); rechargeable battery; AC power converter; capacitor; and combinations of one or more of these. In some embodiments, power supply  557 / 570  comprises two or more batteries, such as two or more rechargeable batteries, such as to allow the first battery to be replaced (e.g. serially replaced) by the second battery. In some embodiments, power supply  557 / 570  is configured to provide a voltage of at least 3V. In some embodiments, power supply  557 / 570  is configured to provide a capacity between 1 Watt-hour and 75 Watt-hours, such as a battery or capacitor with a capacity of approximately 5 Watt-hours. In some embodiments, power supply  557 / 570  comprises an AC power source. 
     Each programmer  550  (singly or collectively programmer  550 ) comprises a programming device configured to control one or more components of apparatus  10 , such as implantable device  200 / 800 . Programmer  550  can comprise a user interface  555 . Programmer  550  can send and/or receive commands to and/or from one or more external devices  500 , such as via a wireless or wired connection (wired connection not shown but such as one or more insulated conductive wires). In some embodiments, one or more external devices  500  comprise programmer  550 , such as when user interface  555  is integrated into housing  510  of external device  500 . In some embodiments, apparatus  10  comprises multiple programmers  550 . 
     Programmer  550  can be configured to adjust one or more parameters of apparatus  10 , such as a stimulation parameter (e.g. a stimulation waveform parameter as described herein); a sensing parameter; a therapy parameter; a data recording parameter (e.g. a patient data recording parameter and/or an implantable device  200 / 800  data recording parameter); power transfer; data rate; activity of one or more external transmitters  553 / 530 ; activity of one or more external antennas  540 ; a stimulation element  260  parameter; a functional element  599  parameter; and combinations of one or more of these. Programmer  550  can be further configured to provide information, such as patient physiologic information recorded by one or more implantable devices  200 / 800 , or apparatus  10  information, such as performance and/or configuration information (singly or collectively “status information”) of one or more external devices  500  and/or implantable devices  200 / 800 . In some embodiments, the programmer  550  uses information recorded by one or more implantable devices  200 , implantable device  800 , apparatus  10  information, and/or information from external devices  500  to adapt configuration parameters of one or more components of apparatus  10 . 
     In some embodiments, programmer  550  comprises a lookup table of stimulation signal waveform patterns, such as to allow a clinician, patient and/or other operator of apparatus  10  to select a predetermined stimulation pattern. In some embodiments, programmer  550  comprises a set of adjustable stimulation signal parameters configured to be varied to allow an operator to construct customized waveforms, such as to vary one or more stimulation parameters described hereabove. In some embodiments, the programmer  550  is configured to allow an operator to create a customized waveform by specifying an amplitude of one or more discrete pulses or steps of a stimulation signal to be delivered by an implantable device  200 / 800 . 
     In some embodiments, programmer  550  comprises a transmitter  553  configured to transmit data to tool  60  or another device such as a cell phone; computer; tablet; computer network such as the internet or a LAN; and combinations of one or more of these. In these embodiments, transmitter  553  can comprise a wireless transmitter; a Bluetooth transmitter; a cellular transmitter; and combinations of one or more of these. In some embodiments, programmer  550  comprises a receiver configured to receive data, or a transceiver configured to both transmit and receive data. 
     User interface  555  of programmer  550  can comprise one or more user input components and/or user output components, such as a component selected from the group consisting of: keyboard; mouse; keypad; switch; membrane switch; touchscreen; display; audio transducer such as a speaker or buzzer; vibrational transducer; light such as an LED; and combinations of one or more of these. 
     In some embodiments, one or more components of external system  50  and/or other external component of apparatus  10 , comprises one or more functional elements  599 , such as functional elements  599   a  and/or  599   b  (singly or collectively functional element  599 ), shown positioned in programmer  550  and in external device  500 , respectively. In some embodiments, one or more components of implantable system  20  can comprise one or more functional elements, such as functional element  299  of implantable device  200  and functional element  899  of implantable device  800 , each shown in  FIG. 1 . Each functional element  299 ,  599  and/or  899  (singly or collectively functional element  299 / 599 / 899 ) can be configured as defined hereabove (e.g. a sensor, a transducer, and/or other functional element as described herein). 
     In some embodiments, a functional element  599  comprises one or more sensors configured to monitor performance of external device  500  and/or programmer  550  (e.g. to monitor the voltage of power supply  570 , quality of transmission of power and/or data to implantable system  20 , temperature of a portion of an external device  500 , and the like). 
     In some embodiments, the functional element  299 / 599 / 899  can comprise an electrode for sensing electrical activity and/or delivering electrical energy. In some embodiments, apparatus  10  is configured to cause stochastic resonance, and the addition of white noise can enhance the sensitivity of nerves to be stimulated and/or boost weak signals to be recorded by the one or more stimulation elements  260  and/or one or more functional elements  299 / 599 / 899 . 
     In some embodiments, one or more functional elements  299 / 599 / 899  comprise a sensor, such as a sensor configured to record data related to a patient parameter (e.g. a patient physiologic parameter), an external system  50  parameter and/or an implantable system  20  parameter. In some embodiments, operation of one or more implantable devices  200 / 800  (e.g. stimulation energy delivered by one or more implantable devices  200 / 800 ) is configured to be delivered based on the data recorded by one or more sensor-based functional elements  299 / 599 / 899 , such as in a closed-loop energy delivery mode. 
     Functional element  299 / 599 / 899  can comprise one or more sensors configured to record data regarding a patient parameter selected from the group consisting of: blood glucose; blood pressure; EKG; heart rate; cardiac output; oxygen level; pH level; pH of blood; pH of a bodily fluid; tissue temperature; inflammation level; bacteria level; type of bacteria present; gas level; blood gas level; neural activity; neural spikes; neural spike shape; action potential; local field potential (LFP); EEG; muscular activity; electrical activity produced by skeletal muscles (e.g. as measured using electromyography, EMG); gastric volume; peristalsis rate; impedance; tissue impedance; electrode-tissue interface impedance; physical activity level; pain level; body position; body motion; organ motion; respiration rate; respiration level; perspiration rate; sleep level; sleep cycle; digestion state; digestion level; urine production; urine flow; bowel movement; tremor; ion concentration; chemical concentration; hormone level; viscosity of a bodily fluid; patient hydration level; and combinations of one or more of these. 
     Functional element  299 / 599 / 899  can comprise one or more sensors configured to record data representing a parameter of external system  50 , implantable system  20 , and/or any component of apparatus  10 . Functional element  299 / 599 / 899  can comprise one or more sensors selected from the group consisting of: an energy sensor; a voltage sensor; a current sensor; a temperature sensor (e.g. a temperature of one or more components of external device  500 , programmer  550 , and/or implantable device  200 / 800 ); an antenna matching and/or mismatching assessment sensor; power transfer sensor; link gain sensor; power use sensor; energy level sensor; energy charge rate sensor; energy discharge rate sensor; impedance sensor; load impedance sensor; instantaneous power usage sensor; average power usage sensor; bit error rate sensor; signal integrity sensor; and combinations of one or more of these. Apparatus  10  can be configured to analyze (e.g. via controller  250  and/or  850  described herebelow) the data recorded by functional element  299 / 599 / 899  to assess one or more of: power transfer; link gain; power use; energy within power supply  557 / 570 ; performance of power supply  557 / 570 ; expected life of power supply  557 / 570 ; discharge rate of power supply  557 / 570 ; ripple or other variations of power supply  557 / 570 ; matching of antennas  240 / 840  and  540 ; communication error rate between implantable device  200 / 800  and external device  500 ; integrity of transmission between implantable device  200 / 800  and external device  500 ; and combinations of one or more of these. 
     In some embodiments, functional element  299  and/or functional element  899  (singly or collectively  299 / 899 ) comprises a sensor configured to produce a signal relating to the level of contamination in an undesired location (e.g. within implantable device  200 / 800  and/or within the connection between implantable device  200 / 800  and lead  265 ). For example, functional element  299 / 899  can comprise a contamination-detecting sensor selected from the group consisting of: pH sensor; optical sensor; chemical sensor; and combinations of one or more of these. In these embodiments, apparatus  10  can be configured to enter an alarm state (e.g. produce an audible, tactile or visual alarm such as an alarm produced by external device  500 , controller  550  and/or implantable device  200 / 800 ) when a contamination level exceeds a threshold. 
     In some embodiments, one or more functional elements  599  are positioned on housing  551  and/or  510  (singly or collectively housing  551 / 510 ). A functional element  599  can comprise a body conduction sensor, such as a body conduction sensor configured to record and/or receive data via skin conduction. A functional element  299 / 599 / 899  can be configured to record data associated with stimulation delivered by one or more implantable devices  200 / 800  (e.g. record data associated with stimulation energy delivered by one or more stimulation elements  260 ), such as to provide closed loop or semi-closed loop stimulation. A functional element  299 / 599 / 899  can be configured to record temperature, such as when apparatus  10  is configured to deactivate or otherwise modify the performance of programmer  550 , external device  500  and/or implantable device  200 / 800  when the recorded temperature (e.g. patient temperature, programmer  550  temperature, external device  500  temperature, and/or implantable device  200 / 800  temperature) exceeds a threshold. 
     In some embodiments, programmer  550 , external device  500 , and/or implantable device  200 / 800  comprises a temperature sensor, such as functional elements  299 / 599 / 899 . The temperature-based functional element  299 / 599 / 899  can be positioned proximate one or more portions of programmer  550 , external device  500 , and/or implantable device  200 / 800 . In these embodiments, the temperature data recorded by the functional element  299 / 599 / 899  is used to adjust one or more of: matching network; stimulation level (e.g. stimulation energy delivered by one or more implantable devices  200 / 800 ); power transmission level (e.g. level of power transmitted between one or more external devices  500  and one or more implantable devices  200 / 800 ); and combinations of one or more of these. In some embodiments, the temperature sensor-based functional element  299 / 599 / 899  is a part of a safety mechanism that deactivates programmer  550 , external device  500 , and/or implantable device  200 / 800  if the recorded temperature exceeds a threshold. Alternatively or additionally, a temperature sensor-based functional element  299 / 599 / 899  can be configured to measure temperature of the patient, such as when placed on housing  551 / 510 , housing  210  and/or housing  810  (singly or collectively housing  210 / 810 ), such as to adjust energy delivery performed by implantable device  200 / 800  based on the recorded patient temperature. 
     In some embodiments, implantable system  20  comprises multiple implantable devices  200 , and implantable system  20  comprises a “multi-point ready” system in which the operation (e.g. energy delivery, data recording and/or other function) of the multiple implantable devices  200  is performed simultaneously, asynchronously, and/or sequentially. The implantable devices  200  can be part of a network including one or more external devices  500  in which the treating of a patient and/or the recording of patient information relies on operation of the implantable devices  200  at one or more implantation sites in a synchronized, asynchronized, and/or otherwise coordinated way. The synchronization or otherwise coordination can be controlled by a single or multiple external devices  500 , which can further be synchronized to a single clock. Each implantable device  200  of implantable system  20  can receive a power signal and/or a data signal from one or more external devices  500 . In some embodiments of the multi-point ready implantable system  20 , each implantable device  200  comprises a unique ID, such that each implantable device  200  can be individually addressed (e.g. receive unique signals from external system  50 ). In some embodiments, external system  50  transmits high-bandwidth signals to implantable system  20 , such that time-domain multiple access communication can be performed while operating in near real time. In some embodiments, implantable system  20  is configured as a multi-point ready system such that stimulation energy delivered by implantable system  20  is independent of power received by implantable system  20  from external system  50 . 
     Two implantable devices  200 , or two discrete components of a single implantable device  200  (e.g. two components comprising or positioned in different housings), can be attached to each other by a connecting filament as defined hereabove. In some embodiments, a connecting filament comprises a user-attachable (e.g. clinician-attachable) connector on at least one end. The filament connector is configured to operably attach to a mating connector on a component (e.g. a housing  210 ) of an implantable device  200 . 
     Each implantable device  200  is configured to receive power and/or data (e.g. implantable system  20  configuration data) from one or more external devices  500 . In some embodiments, one or more implantable devices  200  are configured to receive both power and data (e.g. simultaneously and/or sequentially) from one or more external devices  500 . In some embodiments, a single external device  500  sends power and/or data to multiple implantable devices  200 . Alternatively or additionally, a single implantable device  200  can receive power and/or data from multiple external devices  500 . In some embodiments, a first external device  500  is positioned on or near the patient&#39;s skin at a location proximate an implanted first implantable device  200 , and a second external device  500  is positioned on or near the patient&#39;s skin (generally “on” the patient&#39;s skin) at a location proximate an implanted second implantable device  200 . In these embodiments, the first external device  500  transmits data and/or power to at least the first implantable device  200  and the second external device  500  transmits data and/or power to at least the second implantable device  200 . 
     In some embodiments, one or more implantable devices  200 / 800  are further configured to transmit data to programmer  550  and/or one or more external devices  500 , such as via one or more antennas  240 / 840  transmitting a signal to one or more antennas  540 . Data transmitted by an implantable device  200 / 800  can comprise patient information (e.g. patient physiologic information recorded by one or more stimulation elements  260  or functional elements  299 / 599 / 899  configured as a physiologic sensor), or implantable device  200 / 800  information (e.g. data recorded by one or more sensors positioned in implantable device  200 / 800 , or other implantable device  200 / 800  configuration and/or performance data). 
     Housing  210 / 810  of each implantable device  200 / 800 , can comprise one or more rigid and/or flexible materials. Housing  210  can surround various components of implantable device  200 , such as antenna  240 , energy storage assembly  270 , controller  250  and/or receiver  230 . Housing  810  can surround various components of implantable device  800 , such as antenna  840 , energy storage assembly  870 , controller  850  and/or receiver  830 . In some embodiments, one or more stimulation elements  260  are positioned in, on and/or within housing  210 / 810 . In some embodiments, housing  210 / 810  surrounds a substrate, such as a flexible and/or foldable printed circuit board, such as multiple discrete or continuous printed circuit boards positioned in different planes (e.g. a flexible or foldable printed circuit board). 
     Housing  210 / 810  can comprise one or more shapes or combination of shapes, such as one or more shapes selected from the group consisting of: disc; pill; cylinder; sphere; oblate spheroid; dish-like shape; bowl-like shape; cone; rectangular prism; trapezoidal prism; a portion of a toroid; and combinations of one or more of these. 
     Housing  210 / 810  can comprise a major axis and a minor axis, as defined hereabove. In some embodiments, housing  210 / 810  comprises a major axis less than or equal to 20 mm, such as a major axis less than or equal to 15 mm, 12 mm or 10 mm. In some embodiments, housing  210 / 810  comprises a minor axis less than or equal to 8 mm, such as a minor axis less than or equal to 6 mm, or less than or equal to 5 mm. Housing  210 / 810  can comprise a wall thickness between 0.1 mm and 1.0 mm, such as a wall thickness between 0.2 mm and 0.5 mm, such as a wall thickness of approximately 0.3 mm. Housing  210 / 810  can comprise a displacement volume less than or equal to 2000 mm 3 , such as less than or equal to 600 mm 3 . 
     Housing  210 / 810  can comprise one or more portions that are transmissive to radiofrequency (RF) signals. In some embodiments, housing  210 / 810  comprises glass. In some embodiments, housing  210 / 810  comprises a material selected from the group consisting of: glass; ceramic; stainless steel; titanium; polyurethane; an organic compound; liquid crystal polymer (LCP); gold; platinum; tungsten; epoxy; a thermoplastic; a thermoset plastic; and combinations of one or more of these. In some embodiments, one or more portions of housing  210 / 810  comprises one or more coatings, such as one or more coatings configured to cause or prevent a physiologic reaction and/or a coating configured to block (e.g. shield) an electromagnetic transmission. 
     Housing  210 / 810  can comprise one or more passageways or other feedthroughs, such as for the passage of a lead, wire, optical fiber, fluid delivery tube, mechanical linkage and/or other conduit through a wall of housing  210 / 810 , such as is described in applicant&#39;s co-pending International PCT Patent Application Serial Number PCT/US2016/016888, titled “Medical Apparatus including an Implantable System and an External System”, filed Feb. 5, 2016; the content of which is incorporated herein by reference in its entirety for all purposes. In some embodiments, housing  210  comprises an array of feedthroughs. In some embodiments, housing  210 / 810  is surrounded by a covering, such as a flexible and/or non-conductive covering, such as a covering made of an elastomer. 
     In some embodiments, one or more implantable devices  200 / 800  comprises one or more anchor elements configured to secure one or more portions of implantable device  200 / 800  to tissue. The one or more anchor elements can comprise one or more anchoring elements selected from the group consisting of: a sleeve such as a silicone sleeve; suture tab; suture eyelet; bone anchor, wire loops; porous mesh; penetrable wing; penetrable tab; bone screw eyelet; tine; pincers; suture slits; and combinations of one or more of these. 
     One or more antennas  240 / 840  can be configured to receive power and/or data, and receiver  230  and/or receiver  830  (singly or collectively receiver  230 / 830 ) can receive the power and/or data from the one or more antennas  240 / 840 , respectively. Each antenna  240 / 840  can comprise one or more implantable antennas, such as one or more antennas positioned within housing  210 / 810 , and/or one or more antennas electrically attached to a connecting filament. In some embodiments, one or more implantable devices  200 / 800  comprise at least two antennas  240 / 840 , or at least three antennas  240 / 840 . Antenna  240 / 840  can be configured to receive power and/or data from one or more external devices  500  and/or programmer  550 , such that an attached receiver  230 / 830  receives the power and/or data. In some embodiments, receiver  830  is not configured to receive power, simply data. In some embodiments, implantable system  20  comprises at least two implantable devices  200 / 800 , each of which comprise one or more (e.g. two or three) antennas  240 / 840  which are positioned within a housing  210 / 810  and/or electrically tethered to a housing  210 / 810 . In some embodiments, an implantable device  200 / 800  comprises a first antenna  240 / 840  positioned in a first plane and a second antenna  240 / 840  positioned in a second plane. The first plane and second plane can be relatively orthogonal planes, or planes oriented between 30° and 90° relative to each other, such as between 40° and 90°, approximately 30°, approximately 45° and/or approximately 60° relative to each other. In some embodiments, an implantable device  200 / 800  comprises a first antenna  240 / 840  positioned in a first plane, a second antenna  240 / 840  positioned in a second plane, and a third antenna  240 / 840  positioned in a third plane. 
     In some embodiments, implantable device  200 / 800  comprises one or more antennas  240 / 840  positioned on a substrate, such as a printed circuit board (PCB), a flexible printed circuit board and/or a foldable substrate (e.g. a substrate comprising rigid portions and hinged portions). In some embodiments, the substrate can be folded or otherwise pivoted to position the various antennas  240 / 840  on differently oriented planes, such as multiple planes oriented between 5° and  900  relative to each other, such as two antennas  240 / 840  positioned on two planes oriented between 30° and 90° or between 40° and 90° relative to each other, or three antennas  240 / 840  positioned on three planes oriented between 5° and  600  relative to each other. Two or more antennas  240 / 840  can be positioned on two or more different planes that are approximately 45° relative to each other, or approximately 60° or approximately 90° relative to each other. 
     Implantable device  200 / 800  can comprise three antennas  240 / 840 . In some embodiments, a first antenna  240 / 840  can comprise an electrical dipole antenna, and the second and third antennas  240 / 840  can be positioned in different planes than the first antenna  240 / 840 . In some embodiments, the three antennas  240 / 840  each comprise a loop antenna, such as when each loop antenna is positioned on a different plane. In some embodiments, a first antenna  240 / 840  comprises an electrical dipole antenna, and a second antenna  240 / 840  and a third antenna  240 / 840  each comprise a loop antenna. In these embodiments, the second antenna  240 / 840  and the third antenna  240 / 840  can be positioned relatively orthogonal to each other (e.g. positioned on two relatively orthogonal planes). In some embodiments, a first antenna  240 / 840  (e.g. an electrical dipole antenna) is positioned outside of housing  210 / 810 , while a second antenna  240 / 840  (e.g. a loop antenna) and a third antenna  240 / 840  (e.g. a loop antenna) are each positioned on, in and/or within housing  210 / 810 . In some embodiments, implantable device  200 / 800  can comprise one or more antennas  240 / 840  in which any combination of antenna types (as described herein) are used in combination. 
     One or more antennas  240 / 840  can comprise an antenna selected from the group consisting of: loop antenna; multiple-turn loop antenna; planar loop antenna; coil antenna; dipole antenna; electric dipole antenna; magnetic dipole antenna; patch antenna; loaded dipole antenna; concentric loop antenna; loop antenna with ferrite core; and combinations of one or more of these. One or more antennas  240 / 840  can comprise a loop antenna, such as an elongated loop antenna or a multiple-turn loop antenna. 
     One or more antennas  240 / 840  can comprise a multi-turn spiral loop antenna, such as a multi-turn spiral loop antenna configured to desensitize coupling sensitivity and/or boost input voltage. In some embodiments, one or more antennas  240 / 840  comprise multiple concentric loops with varied dimensions, such as concentric loops configured to desensitize coupling sensitivity. In these embodiments, the multiple concentric loops can be: connected in parallel and driven from the same feed point; driven from the same feed point and connected using one or more of a capacitor, inductor, varactor, and combinations of one or more of these; and/or driven from multiple feed points. 
     One or more antennas  240 / 840  can comprise a minor axis and a major axis. In some embodiments, one or more antennas  240 / 840  comprise a minor axis between 1 mm and 8 mm, such as between 2 mm and 5 mm. In some embodiments, one or more antennas  240 / 840  comprise a major axis between 3 mm and 15 mm, such as between 4 mm and 8 mm. In some embodiments, one or more antennas  240 / 840  comprise a major axis above 3 mm, such as between 3 mm and 15 mm, such as when the antenna  240 / 840  is positioned outside of housing  210 / 810 . 
     One or more antennas  240 / 840  can comprise a foldable and/or unfoldable antenna, such as is described in applicant&#39;s co-pending U.S. patent application Ser. No. 14/975,358, titled “Method and Apparatus for Minimally Invasive Implantable Modulators”, filed Dec. 18, 2015, the content of which is incorporated herein by reference in its entirety for all purposes. 
     One or more antennas  240 / 840  can be positioned inside of housing  210 / 810 . Alternatively or additionally, one or more antennas  240 / 840  can be positioned outside of housing  210 / 810 . 
     Implantable system  20 , one or more implantable devices  200 / 800  and/or one or more antennas  240 / 840  can be configured to be positioned at a desired depth beneath the patient&#39;s skin, such as at a depth between 0.5 cm and 7.0 cm, such as a depth of between 1.0 cm and 3.0 cm. In some embodiments, one or more antennas  840  are positioned at a deeper implant location than the depth at which one or more antennas  240  are implanted. 
     One or more energy storage assemblies  270  and/or  870  (singly or collectively energy storage assembly  270 / 870 ) can comprise one or more implantable energy storage components, such as one or more batteries (e.g. rechargeable batteries) and/or capacitors (e.g. a supercapacitor). Energy storage assembly  270 / 870  can be configured to provide power to one or more of: one or more stimulation elements  260 ; controller  250 / 850 ; receiver  230 / 830 ; and combinations of one or more of these. In some embodiments, energy storage assembly  270 / 870  further provides power to one or more antennas  240 / 840  and/or circuitry configured to transmit data via antenna  240 / 840 . In some embodiments, energy storage assembly  270 / 870  includes digital control for charge/discharge rates, voltage outputs, current outputs, and/or system power distribution and/or management. 
     Energy storage assembly  270 / 870  can comprise one or more capacitors with a single or collective capacitance between 0.01 μF and 10 F, such as a capacitance between 1 μF and 1.0 mF, or between 1 μF and 10 μF. Energy storage assembly  270 / 870  can comprise one or more capacitors with a capacitance between 1 mF and 10 F, such as when energy storage assembly  270 / 870  comprises a super-capacitor and/or an ultra-capacitor. Such large capacitance can be used to store sufficient charge to maintain operation (e.g. maintain delivery of stimulation energy and/or delivery of an agent) without the use (e.g. sufficient proximity) of an associated power-providing external device  500 . A capacitor or other energy storage element (e.g. a battery) can be chosen to provide sufficient energy to maintain operation for at least 30 seconds, at least 2 minutes, at least 5 minutes, at least 30 minutes, and/or up to several hours or more (e.g. during showering, swimming or other physical activity). In some embodiments, energy storage assembly  270 / 870  is configured to provide continuous and/or intermittent stimulation energy for at least one charge-balanced pulse (e.g. for the duration of at least one charge-balanced pulse). In some embodiments, a capacitor, battery or other energy storage element is configured to provide stimulation energy without receiving externally supplied power for periods of at least 1 hour, at least 1 day, at least 1 month or at least 1 year (e.g. when implantable device  800  is configured to provide long term stimulation without externally received power). Energy storage assembly  270 / 870  can comprise one or more capacitors with a breakdown voltage above 1.0V, such as a breakdown voltage above 1.5V, 4.0V, 10V, or 15V. In some embodiments, energy storage assembly  270 / 870  can comprise capacitors distributed outside of housing  210 / 810 , such as when one or more capacitors are distributed along lead  265 . Energy storage assembly  270 / 870  can comprise one or more capacitors with low self-leakage, such as to maintain stored energy for longer periods of time. 
     In some embodiments, energy storage assembly  270 / 870 , particularly energy storage assembly  270 , comprises a temporary energy storage component, such as a super-capacitor, configured to store a sufficient quantity of energy to provide uninterrupted stimulation, such as during time periods in which the link gain may be of poor quality or it may be temporarily unavailable (e.g. an external device  500  sending power to an implantable device  200  that is not in place, such as during a shower, swimming, and the like). An energy storage assembly  270  comprising an ultra-capacitor, super-capacitor or flexible battery can be charged via the wireless power transmission of the present inventive concepts, such as to store a sufficient amount of energy for one or more stimulation elements  260  to deliver stimulation energy during subsequent (intended or unintended) unavailability of one or more external devices  500  (e.g. an external device  500  is intentionally removed or unintentionally falls off or otherwise loses its position sufficiently proximate one or more implantable devices  200 ). An energy storage assembly  270  comprising one or more high capacity energy storage components can be beneficial in applications where therapy interruption provides a significant risk or is otherwise relatively unacceptable, such as for life support therapies, cardiac resynchronization therapies, and the like. The high capacity energy storage components of energy storage assembly  270  can be positioned in an assembly positioned within housing  210 , on an inner or outer surface of housing  210 , within a separate housing, and/or within lead  265 . 
     In some embodiments, implantable device  200  receives power regularly from external system  20  (e.g. relatively continuously while implantable device  200  delivers stimulation energy), and energy storage assembly  270  comprises a relatively small battery or capacitor, such as a battery or capacitor that has an energy storage capacity of less than or equal to 0.6 Joules, 7 Joules or 40 Joules. In these embodiments, implantable device  800  can receive no or minimal power regularly from external system  20  (e.g. stimulation energy delivered by implantable device  800  is provided by energy storage assembly  870 ), and energy storage assembly  870  comprises a larger battery or capacitor than energy storage assembly  270 . For example, energy storage assembly  870  can be configured to store at least 10 times the power stored in energy storage assembly  270 , or at least 100 times or 500 times the power stored in energy storage assembly  270 . In some embodiments, energy storage assembly  870  has a capacity of at least 60 Joules, 700 Joules, or 4,000 Joules. 
     One or more controllers  250  and/or  850  (singly or collectively controller  250 / 850 ) can be configured to control one or more stimulation elements  260 , such as a stimulation element  260  comprising an energy-delivering transducer (e.g. an electrode or other energy delivery element) and/or a sensor (e.g. a physiologic sensor and/or a sensor configured to monitor an implantable device  200 / 800  parameter). In some embodiments, controller  250 / 850  is configured to transmit a stimulation signal (e.g. transmit stimulation energy configured in one or more stimulation waveforms) to one or more stimulation elements  260  (e.g. one or more stimulation elements  260  comprising an electrode and/or other energy delivery element), independent of the power signal received by one or more antennas  240 / 840  (e.g. independent of power transmitted by external system  50 ), such as by using energy stored in energy storage assembly  270 / 870 . In these embodiments, the power signal and/or the RF path for the power signal can be adjusted to optimize power efficiency (e.g. by tuning matching network on transmitter  530  and/or receiver  230 / 830 ; configuring antennas  540  and/or  240 / 840  in an array; tuning operating frequency; duty cycling the power signal; adjusting antenna  540  and/or  240 / 840  position; and the like), and a stimulation signal can be precisely delivered (e.g. by using energy stored on energy storage assembly  270 / 870  and generating a stimulation signal locally on the implantable device  200 / 800 ) to ensure clinical efficacy. Also, if the power signal transmission (also referred to as “power link”) is perturbed unexpectedly, the stimulation signal can be configured so that it is not significantly affected (e.g. unaffected). In some configurations, the stimulation signal being delivered by one or more implantable devices  200 / 800  can be insensitive to interference that may be present. In these embodiments, a power transmission signal and stimulation signal can vary in one or more of: amplitude; changes in amplitude; average amplitude; frequency; changes in frequency; average frequency; phase; changes in phase; average phase; waveform shape; pulse shape; duty cycle; polarity; and combinations of one or more of these. 
     Controller  250 / 850  can receive commands from receiver  230 / 830 , such as one or more commands related to one or more implantable device  200 / 800  configuration parameters selected from the group consisting of: stimulation parameter; data rate of receiver; data rate of data transmitted by implantable antenna  240 / 840 ; stimulation element  260  configuration; state of controller  250 / 850 ; antenna  240 / 840  impedance; clock frequency; sensor configuration; electrode configuration; power management parameter; energy storage assembly parameter; agent delivery parameter; sensor configuration parameter; and combinations of one or more of these. 
     In some embodiments, one or more stimulation elements  260  comprise a stimulation element configured to deliver energy (e.g. one or more electrodes configured to deliver monopolar or bipolar electrical energy) to tissue, and controller  250 / 850  is configured to control the energy delivery, such as to control one or more stimulation parameters as described herein. Each of these stimulation parameters can be held relatively constant, and/or varied, such as a variation performed in a continuous or intermittent manner. In some embodiments, one or more stimulation parameters are varied in a random or pseudo-random (hereinafter “random”) manner, such as a variation performed by apparatus  10  using a probability distribution as described in applicant&#39;s co-pending International PCT Patent Application Serial Number PCT/US2017/017978, titled “Apparatus with Enhanced Stimulation Waveforms”, filed Feb. 15, 2017, the content of which is incorporated herein by reference in its entirety for all purposes. In some embodiments, stimulation (e.g. stimulation comprising high frequency and/or low frequency signal components) is varied randomly to eliminate or at least reduce synchrony of neuronal firing with the stimulation signal (e.g. to reduce paresthesia or other patient discomfort). In some embodiments, one or more stimulation elements  260  comprise a stimulation element configured to stimulate a target (e.g. nerve tissue such as spinal nerve tissue and/or peripheral nerve tissue). The amount of stimulation delivered to the target can be controlled by varying a parameter selected from the group consisting of: stimulation element  260  size and/or configuration (e.g. electrode size and/or configuration); stimulation element  260  shape (e.g. electrode shape, magnetic field generating transducer shape or agent delivering element shape); shape of a generated electric field; shape of a generated magnetic field; stimulation signal parameters; and combinations of one or more of these. 
     In some embodiments, one or more stimulation elements  260  comprise an element configured to deliver electrical energy to tissue (e.g. one or more electrodes configured to deliver monopolar or bipolar electrical energy), and controller  250 / 850  is configured to control charge balance, such as to actively and/or passively control charge balance, as described herebelow. Charge balance can be essential for patient safety in electrical stimulation of nerves or other tissue. Imbalanced stimulation waveforms can cause electrode corrosion and/or dissolution which can lead to deposition of toxic materials in tissue, implant rejection, and nerve damage. The stimulation waveform can be balanced such that net outflow charge approximately equals net inflow charge. With stimulation waveform amplitudes that can vary between 0.01 mA to 15 mA (such as between 0.01 mA and 12 mA, or between 0.01 mA and 10 mA), depending on the treatment, the error in charge balance can be on the order of 0.0010% to 0.01%. Alternatively or additionally, controller  250 / 850  can comprise AC coupling capacitors that are configured to balance stimulation waveforms passively. The AC coupling capacitance can be fairly large (e.g. greater than 10 μF), in order to pass the stimulation waveform with minimal filtering. In some embodiments, apparatus  10  can be configured to perform active charge balancing. In some embodiments, an implantable device  200 / 800  can comprise a precise resistor in series with a stimulation electrode-based stimulation element  260 . The precise resistor can be used to measure outflow and inflow currents, such as when controller  250 / 850  comprises an analog to digital converter (ADC). Controller  250 / 850  can integrate current over time during a first phase in which stimulation energy is delivered, and during a second phase in which a reverse current is applied (e.g. a reverse current used to balance charge). Controller  250 / 850  can be configured to balance the total charge in the two phases, to ensure that the net DC current is approximately zero. The integration can be achieved using an analog integrator and/or a digital summer of controller  250 / 850 , with controller  250 / 850  keeping track of one or more parameters of the pulses delivered (e.g. pulses delivered within a train or a burst). Implantable device  200 / 800  can comprise a precise series resistance comprising an on-chip trimmed resistor or an off chip resistor. In some embodiments, implantable device  200 / 800  comprises a bank of trimmed resistors that are used to control the net series resistance, such as to adjust resistance based on stimulation amplitude requirements (e.g. to take advantage of the full dynamic range of an ADC of controller  250 / 850 ). In some embodiments, controller  250 / 850  comprises a shunt path with an RC-based low pass filter used for both outflow and inflow of current. RC elements of controller  250 / 850  can be chosen such that the shunt current is only a fraction of the stimulation current. Since the same RC elements can be used for both outflow and inflow current, the precision required for the RC components can be lower. An ADC can be used to sense the voltage on the capacitor at the end of a stimulation pulse. After the stimulation pulse, the capacitor can be discharged and the polarity of the stimulation current can be reversed and set to any amplitude, until the capacitor is charged to approximately the same voltage (according to the ADC precision) as it was charged during the stimulation pulse. The ADC resolution can be high enough to ensure the residual error is less than what would cause an undesired charge accumulation. ADC resolution requirements can be further reduced by reducing the net capacitance in a shunt RC circuit, to cause accelerated charging of the capacitor. The capacitor can be discharged every time the voltage exceeds a certain predefined threshold, while controller  250 / 850  keeps track of the number of times the capacitor has been charged and reset. By resetting the capacitor through a low resistance path, the discharge time can be insignificant compared to the charge time, reducing the error due to the discharge period. Since the net charge equivalent to full scale voltage on the ADC can be divided into multiple cycles, the required resolution of the ADC to achieve the same residual error can be divided by the number of cycles. 
     In some embodiments, controller  250 / 850  is configured to produce a stimulation signal comprising a waveform or a waveform pattern (hereinafter stimulation waveform), for one or more stimulation elements  260  configured as a stimulation element (e.g. such that one or more stimulation elements  260  deliver stimulation energy comprising or at least resembling that stimulation waveform). Controller  250 / 850  can produce a stimulation signal comprising a waveform selected from the group consisting of: square wave; rectangle wave; sine wave; sawtooth; triangle wave (e.g. symmetric or asymmetric); trapezoidal; ramp; waveform with exponential increase; waveform with exponential decrease; pulse shape which minimizes power consumption; Gaussian pulse shape; pulse train; root-raised cosine; bipolar pulses; and combinations of one or more of these. In some embodiments, controller  250 / 850  is configured to produce a stimulation signal comprising a waveform including a combination of two or more waveforms selected from the group consisting of: square wave; rectangle wave; sine wave; triangle wave (symmetric or asymmetric); trapezoidal; ramp; waveform with exponential increase; waveform with exponential decrease; pulse shape which minimizes power consumption; Gaussian pulse shape; pulse train; root-raised cosine; bipolar pulses; and combinations of one or more of these. In some embodiments, controller  250 / 850  is configured to construct a custom waveform (e.g. an operator customized waveform), such as by adjusting amplitude at specified time steps (e.g. for one or more pulses). In some embodiments, controller  250 / 850  is configured to generate a waveform including one or more random parameters (e.g. random timing of pulses or random changes in frequency, rate of change or amplitude). 
     In some embodiments, controller  250 / 850  is configured to provide a stimulation signal comprising waveforms and/or pulses repeated at a frequency (e.g. includes a frequency component) between 1.0 Hz and 50 KHz, such as between 10 Hz and 500 Hz, between 40 Hz and 160 Hz and/or between 5 KHz and 15 KHz. In some embodiments, controller  250 / 850  is configured to produce a stimulation signal comprising a frequency between 1 Hz and 1000 Hz, such as a stimulation signal with a frequency between 10 Hz and 500 Hz. In some embodiments, controller  250 / 850  is configured to produce a stimulation signal comprising a duty cycle between 0.1% and 99%, such as a duty cycle between 1% and 10% or between 1% and 25%. In some embodiments, controller  250 / 850  is configured to produce a stimulation signal comprising a frequency modulated stimulation waveform, such as a stimulation waveform comprising a frequency component (e.g. signal) between 1 kHz and 20 kHz. In some embodiments, controller  250 / 850  is configured to produce a stimulation signal comprising a mix and/or modulation of low frequency and high frequency signals, which can be of any of the waveform types, shapes and other configurations as described herein. In these embodiments, the stimulation signal can comprise low frequency signals between 1 Hz and 1000 Hz, and high frequency signals between 600 Hz and 50 kHz, or between 1 kHz and 20 kHz. Alternatively or additionally, the stimulation signal can comprise a train of high frequency signals and bursts of low frequency signals, and/or a train of low frequency signals and bursts of high frequency signals. Alternatively or additionally, the stimulation signal can comprise one or more high frequency signals modulated with one or more low frequency signals, such as one or more high frequency signals frequency modulated (FM), amplitude modulated (AM), phase modulated (PM) and/or pulse width modulated (PWM) with one or more low frequency signals. The stimulation signal can cycle among different waveforms shapes at specified time intervals. The stimulation signal can comprise a pseudo random binary sequence (PRBS) non-return-to-zero or return-to-zero waveform, such as with a fixed and/or time-varying pulse width and/or frequency of the pulses. 
     Controller  250 / 850  can comprise a clamping circuit configured to allow fast charging and/or discharging of the energy storage assembly  270 / 870 , stimulation element  260  drivers (e.g. electrode drivers) of controller  250 / 850 , and/or other components of implantable device  200 / 800 . The clamping circuit can improve pulse shape by offering additional control and/or configuration of rise and fall times in the shape of the waveform (e.g. to create rapid rise or fall times). In some embodiments, the clamping circuit can be configured to limit the rise and/or fall time to be less than or equal to one-tenth (10%) of the pulse width of an applied stimulation pulse (e.g. less than or equal to 1 μs rise and/or fall time for a 10 μs stimulation pulse). 
     In some embodiments, controller  250 / 850  comprises a matching network configured to match the impedance of a first antenna  240 / 840  with the impedance of the receiver  230 / 830 . In these embodiments, controller  250 / 850 &#39;s matching network can be adjustable. Alternatively or additionally, controller  250 / 850  can comprise an adjustable loading impedance to stabilize the load seen at an antenna  240 / 840  under different operating conditions. In some embodiments, the adjustable loading impedance is controlled according to the charge rate of the energy storage assembly  270 / 870 . 
     Controller  250 / 850  and/or any other component of each implantable device  200 / 800  can comprise an integrated circuit comprising one or more components selected from the group consisting of: matching network; rectifier; DC-DC converter; regulator; bandgap reference; overvoltage protection; overcurrent protection; active charge balance circuit; analog to digital converter (ADC); digital to analog converter (DAC); current driver; voltage driver; digital controller; clock generator; data receiver; data demodulator; data modulator; data transmitter; electrode drivers; sensing interface analog front end; power management circuit; energy storage interface; memory register; timing circuit; and combinations of one or more of these. 
     One or more receivers  230 / 830  can each comprise one or more components, such as a demodulator, a rectifier and/or a power converter. In some embodiments, receiver  230 / 830  can comprise a DC-DC converter such as a boost converter. Receiver  230 / 830  can comprise a data receiver, such as a data receiver including an envelope detector and demodulator and/or an envelope averaging circuit. In some embodiments, one more antennas  240 / 840  separately connect to one or more receivers  230 / 830 . In some embodiments, one or more antennas  240 / 840  connect to a single receiver  230 / 830 , such as via a series connection or a parallel connection. 
     One or more implantable devices  200 / 800  can be configured to transmit a data signal to external system  50 . In some embodiments, receiver  230 / 830  is configured to drive one or more antennas  240 / 840  to transmit data to external system  50  (e.g. to an antenna  540   a  of programmer  550  or antenna  540   b  of an external device  500 ). Alternatively or additionally, implantable device  200 / 800  can be configured to transmit a data signal by having receiver  230 / 830  adjust a load impedance to backscatter energy, such as a backscattering of energy which can be detected by external system  50 . In some embodiments, data transmission is accomplished by receiver  230 / 830  manipulating a signal at a tissue interface, such as to transmit a data signal using body conduction. 
     In some embodiments, receiver  230 / 830  comprises a matching network, such as a matching network configured to detune to prevent oversaturation. For example, implantable system  20  can comprise two or more implantable devices  200 / 800 , and each of which can include a receiver  230 / 830  comprising a matching network. A first implantable device  200 / 800 &#39;s receiver  230 / 830 &#39;s matching network can be configured to detune based on power received by the second implantable device  200 / 800 &#39;s receiver  230 / 830 . 
     A demodulator portion of receiver  230 / 830  can comprise circuitry that asynchronously recovers signals modulated on the power signal provided by external system  50 , and converts the modulated signals into digital signals. In some embodiments, the demodulator asynchronously recovers the modulated signal by comparing a dynamically generated moving average with the envelope, outputting a high voltage when the envelope is greater than the moving average and a low voltage when the envelope is less than the moving average. Data can then be extracted from this resulting digital signal from the width and/or amplitude of the pulses in the signal, according to the encoding method used by external system  50 . In some embodiments, the demodulator recovers a digital signal that can be used as timing information for an implantable device  200 / 800 , similar to an on-chip clock. The recovered clock signal can also be used to synchronize an on-chip clock generator of controller  250 / 850 , such as through the use of a frequency and/or phase locked loop (FLL or PLL). 
     A rectifier portion of receiver  230 / 830  can comprise a power signal rectifier, such as to provide power to the energy storage assembly  270 / 870  and/or controller  250 / 850 . In some embodiments, the rectifier comprises one or more self-driven synchronous rectifier (SDSR) stages connected in charge-pump configuration, to boost the voltage from an input RF amplitude to the rectifier, to a higher voltage. The boosted voltage can directly charge energy storage assembly  270 / 870 , or be further boosted by a DC-DC converter or boost converter. In some embodiments, the rectifier can comprise diode-capacitor ladder stages instead of, or in addition to, SDSR stages. On-chip diodes, such as Schottky diodes, or off-chip diodes can be used in one or more rectifier stages. For maximum efficiency, the rectification elements, such as diodes, can be optimized to minimize forward conduction and/or reverse conduction losses by properly sizing the components and selecting appropriate number of stages based on the input RF voltage and load current. 
     A power converter portion of receiver  230 / 830  can comprise one or more voltage conversion elements such as DC-DC converters that boost or otherwise change the voltage to a desired level. In some embodiments, voltage conversion is achieved with a buck-boost converter, a boost converter, a switched capacitor, and/or charge pumps. One or more power converters can interface with energy storage assembly  270 / 870  and charge up associated energy storage components to desired voltages. In some embodiments, a power converter receives control signals from controller  250 / 850 , such as to configure voltages, currents, charge/discharge rates, switching frequencies, and/or other operating parameters of the power converter. 
     One or more implantable leads  265  (singly or collectively lead  265 ) can be attached to one or more housings  210 / 810 , such as at attachment port  290  of implantable device  200  and/or attachment port  890  of implantable device  800 . In some embodiments, various components of implantable system  20  are implanted in multiple clinical procedures, such as is described herebelow in reference to  FIG. 2 . For example, implantable device  200  can be implanted in a first clinical procedure in which lead  265  is also implanted. In this first clinical procedure, lead  265  is operably attached to implantable device  200  via attachment port  290 . After the first clinical procedure, a “trial period” ensues in which stimulation is provided in order to evaluate use of apparatus  10  to provide therapy to the patient. During the trial period, stimulation settings can be varied (e.g. variations of: stimulation element  260  positions, configurations and/or combinations; stimulation frequencies; stimulation waveform shapes; and/or stimulation pulse width and/or amplitude). Today&#39;s clinical practice can include use of an external stimulator during an evaluation period (e.g. similar to the “trial period” described herein) of a future implanted stimulator, such as an external stimulator that attaches to an implanted lead (e.g. a lead similar to lead  265 ), via a transcutaneous conduit. This external stimulator approach during the evaluation period has numerous disadvantages including risk of infection, which limits the duration of the evaluation period. Apparatus  10  of the present inventive concepts includes implantable stimulator  200 , which is implanted in the patient for use in the trial period, avoiding any transcutaneous conduits. Use of the implanted stimulator of the present inventive concepts during an evaluation phase can provide numerous advantages, including but not limited to extended length of the trial period (e.g. due to the decreased risk of infection of a fully implanted device), such as a trial period that lasts at least 1 week, at least 2 weeks, at least 1 month, at least 2 months, and/or at least 3 months, greatly reduced risk of dislocating the implanted lead (e.g. a dislocation which could occur with inadvertent tugging on a transcutaneous conduit), simplification of patient bathing (e.g. due to avoidance of transcutaneous conduit), and/or improved patient experience with apparatus (since long term device similarly does not include transcutaneous conduit). Use of implantable stimulator  200  versus an external simulator, during a trialing period as described herein, provides the patient with a similar experience to that which will be encountered with implantable stimulator  800  (e.g. since both are implanted). During the trialing period, implantable device  200  receives power and data from one or more external devices  500 , as is described herein, avoiding the need for a large capacity energy storage assembly  270  (e.g. reducing the volume of implantable device  200 ). After the trialing period, in a second clinical procedure, implantable device  200  is detached from lead  265 , and implantable device  800  is attached to lead  265  and implanted in the patient (in any order). After implantation, implantable device  800  provides long-term therapy to the patient for a therapy period (e.g. a period of at least 1 month, at least 6 months, at least 1 year or at least 2 years). During the therapy period, implantable device  800  may not receive any power from external system  50 , such as when energy storage assembly  870  comprises a capacity sufficient to deliver stimulation for the entire therapy period. In alternative embodiments, energy storage assembly  870  is recharged periodically (e.g. not continuously), such as via a wireless recharge (e.g. via a RF or other wireless transmitter, magnetic coupling, inductive coupling, capacitive coupling and/or other wireless power transmission means). 
     Lead  265  comprises proximal portion  268 , distal portion  269 , and a shaft (e.g. a flexible shaft), shaft  261 . Lead  265  comprises at least one stimulation element  260 , such as two, three, four or more stimulation elements (three shown positioned on distal portion  269  in  FIG. 1 ). Stimulation elements  260  can comprise electrodes or other energy delivering elements. Stimulation element  260  can comprise two or more electrodes configured to deliver energy in monopolar or bipolar energy delivery modes. In some embodiments, one or more stimulation elements  260  and/or other component of implantable device  200 / 800  (e.g. functional elements  299  and/or  899 ) can be configured as a physiologic sensor (e.g. an electrode configured to record electrical activity of tissue or other physiologic sensor as described herein). One or more stimulation elements  260  can be configured to transmit signals through tissue to one or more components of external system  50 , such as through body conduction. 
     Stimulation elements  260  are operatively connected (e.g. electrically, optically, and/or acoustically connected) to contacts  262  via conduit  263  (e.g. one or more wires, optical fibers, wave guides, and the like). Contacts  262 , shown positioned on proximal portion  268  of lead  265 , are constructed and arranged to operatively connect to contacts  292  of attachment port  290  (e.g. in a first clinical procedure), and contacts  892  of attachment port  890  (e.g. in a subsequent, second clinical procedure). Contacts  292  and/or  892  (contacts  292 / 892  herein) are operatively connected with various components of implantable device  200 / 800  such that stimulation energy can be provided by implantable device  200 / 800  to stimulation elements  260  via attachment port  290 / 890  and conduit  263 . 
     In some embodiments, lead  265  comprises a removable stylet configured to aid in the implantation of lead  265 , such as is described in applicant&#39;s co-pending International PCT Patent Application Serial Number PCT/US2016/016888, titled “Medical Apparatus including an Implantable System and an External System”, filed Feb. 5, 2016; the content of which is incorporated herein by reference in its entirety for all purposes. In some embodiments, implantable system  20  comprises more than one lead  265 , each comprising one or more stimulation elements  260  and attached to one or more attachment ports  290 / 890  of one or more implantable devices  200 / 800 . 
     In some embodiments, lead  265  comprises a diameter between 1 mm and 4 mm, such as a diameter between 1 mm and 2 mm. In some embodiments, lead  265  comprises a length between 3 cm and 60 cm, such as a length between 6 cm and 30 cm. One or more leads  265  can include between 2-64 stimulation elements  260 , such as when a lead  265  comprises between 2 and 64 electrodes, such as between 4 and 32 electrodes. In some embodiments, lead  265  comprises a paddle lead. In some embodiments, stimulation element  260  comprises one or more electrodes selected from the group consisting of: microelectrode; cuff electrode; array of electrodes; linear array of electrodes; circular array of electrodes; paddle-shaped array of electrodes; bifurcated electrodes; and combinations of one or more of these. 
     In some embodiments, stimulation element  260  comprises one or more elements positioned proximate and/or within one or more tissue types and/or locations selected from the group consisting of: one or more nerves; one or more locations along, in and/or proximate to the spinal cord; peripheral nerves of the spinal cord including locations around the back; the knee, the tibial nerve (and/or sensory fibers that lead to the tibial nerve); the occipital nerve; the sphenopalatine ganglion; the sacral and/or pudendal nerve; brain tissue, such as the thalamus; baroreceptors in a blood vessel wall, such as in the carotid artery; one or more muscles; the medial nerve; the hypoglossal nerve and/or one or more muscles of the tongue; cardiac tissue; the anal sphincter; the dorsal root ganglion; motor nerves; muscle tissue; the spine; the vagus nerve; the renal nerve; an organ; the heart; the liver; the kidney; an artery; a vein; bone; and combinations of one or more of these, such as to stimulate and/or record data from the tissue and/or location in which the stimulation element  260  is positioned proximate to and/or within. In some embodiments, apparatus  10 , implantable device  200 , implantable device  800 , and/or stimulation element  260  are configured to stimulate spinal nerves, peripheral nerves and/or other tissue as described in applicant&#39;s co-pending application International PCT Patent Serial Number PCT/US2016/051177, titled “Apparatus for Peripheral or Spinal Stimulation”, filed Sep. 9, 2016. 
     In some embodiments, stimulation element  260  or a component of implantable device  200 / 800  comprises one or more sensors configured to record data representing a physiologic parameter of the patient. Stimulation element  260  can comprise one or more sensors selected from the group consisting of: electrode; sensor configured to record electrical activity of tissue; blood glucose sensor; gas sensor; blood gas sensor; ion concentration sensor; oxygen sensor; pressure sensor; blood pressure sensor; heart rate sensor; cardiac output sensor; inflammation sensor; neural activity sensor; neural spike sensor; muscular activity sensor; EMG sensor, bladder volume sensor, bladder pressure sensor, gastric volume sensor; peristalsis rate sensor; pH sensor; strain gauge; accelerometer; gyroscope; GPS; respiration sensor; respiration rate sensor; flow sensor; viscosity sensor; temperature sensor; magnetic sensor; optical sensor; MEMs sensor; chemical sensor; hormone sensor; impedance sensor; tissue impedance sensor; electrode-tissue interface impedance sensor; body position sensor; body motion sensor; organ motion sensor; physical activity level sensor; perspiration sensor; patient hydration sensor; breath monitoring sensor; sleep monitoring sensor; food intake monitoring sensor; digestion monitoring sensor; urine movement sensor; bowel movement sensor; tremor sensor; pain level sensor; and combinations of one or more of these. 
     Apparatus  10  and stimulation element  260  can be configured to record a patient parameter (e.g. patient physiologic and/or patient environment parameter) selected from the group consisting of: blood glucose; blood pressure; EKG; heart rate; cardiac output; oxygen level; pH level; pH of blood; pH of a bodily fluids; tissue temperature; inflammation level; bacteria level; type of bacteria present; gas level; blood gas level; neural activity; neural spikes; neural spike shape; action potential; local field potential (LFP); EEG; muscular activity; skeletal muscle activity; bladder volume; bladder pressure; gastric volume; peristalsis rate; impedance; tissue impedance; electrode-tissue interface impedance; physical activity level; pain level; body position; body motion; organ motion; respiration rate; respiration level; perspiration rate; sleep level; sleep cycle; digestion state; digestion level; urine production; urine flow; bowel movement; tremor; ion concentration; chemical concentration; hormone level; viscosity of a bodily fluid; patient hydration level; and combinations of one or more of these. 
     In some embodiments, apparatus  10  comprises tool  60 . Tool  60  can comprise a data logging and/or analysis tool configured to receive data from external system  50  or implantable system  20 , such as data comprising: diagnostic information recorded by external system  50  and/or implantable system  20 ; therapeutic information recorded by external system  50  and/or implantable system  20 ; patient information (e.g. patient physiologic information) recorded by implantable system  20 ; patient environment information recorded by implantable system  20 ; and combinations of one or more of these. Tool  60  can be configured to receive data from wired or wireless (e.g. Bluetooth) means. Tool  60  can comprise a tool selected from the group consisting of: a data logging and/or storage tool; a data analysis tool; a network such as a LAN or the Internet; a cell phone; and combinations of one or more of these. 
     In some embodiments, tool  60  comprises a battery charging assembly, such as an assembly configured to recharge one or more power supplies  557  and/or  570  comprising a rechargeable battery or capacitor. 
     In some embodiments, tool  60  comprises an implantation tool, such as an introducer or other implantation tool constructed and arranged to aid in the implantation of housing  210 , housing  810 , implantable antenna  240 , implantable antenna  840 , lead  265  and/or one or more stimulation elements  260 . 
     In some embodiments, lead  265  comprises a paddle lead or other stimulating lead and tool  60  comprises an introducer (e.g. a needle or an extended-width introducer) configured to deliver at least a distal portion of lead  265  into an epidural space of a patient. Tool  60  can comprise an introducer comprising a Tuohy needle, such as a Tuohy needle of 12 gauge or smaller. Tool  60  can comprise a handle for manipulating lead  265 . Tool  60  can be configured to place lead  265  at an entry point above the lumbar spinal column (e.g. between L1 and L2 vertebrae). Tool  60  can include extension tubing used to insert lead  265 . Tool  60  can further comprise a tool configured to anchor lead  265 , such as when tool  60  comprises sutures, clips, other anchoring elements and/or an anchor securing tool (e.g. a needle or a stapling device), such as to secure lead  265  in subcutaneous tissue. Lead  265  and/or tool  60  can comprise extension tubing used to place lead  265 , such as extension tubing that remains in place after removal of an introducer of tool  60 . Tool  60  can be configured to place lead  265  against the dura of the spinal cord of the patient. 
     In some embodiments, tool  60  and/or lead  265  are constructed and arranged to implant lead  265  to stimulate one or more multifidus (MF) muscle fascicles, such as at least three sets of multifidus muscle fascicles. Lead  265  can be secured to a vertebra (e.g. on the transverse process, lamina or vertebral body). Lead  265  can be placed via tool  60  such that one or more stimulation elements  260  (e.g. electrodes) are positioned within the multifidus muscle structures. One or more stimulation elements  260  can be positioned to deliver electrical energy and/or to otherwise stimulate tissue selected from the group consisting of: muscle motor point(s) or the deep fibers of lumbar multifidus; quadratus lumborum; the erector spinae; psoas major; transverse abdominis; connective tissue such as the annulus or facet capsule; ligaments coupling bony structures of the spine; and combinations of one or more of these. Stimulation elements  260  can be positioned to: depolarize, hyperpolarize and/or block innervated sections of the muscle that will then propagate an activating and/or inhibiting stimulus along the nerve fibers recruiting muscle tissue remote from the site of stimulation and/or modulate nerve activity (including inhibiting nerve conduction, improving nerve conduction and/or improving muscle activity). In some embodiments, stimulation elements  260  are positioned to cause transvascular stimulation (e.g. transvascular stimulation from arteries and/or veins in a leg or arm). In some embodiments, stimulation elements  260  are positioned to stimulate nerve tissue selected from the group consisting of: dorsal ramus nerve; medial branch of dorsal ramus nerve; nervous tissue associated with multifidus muscle; and combinations of one or more of these. In some embodiments, stimulation elements  260  are configured to deliver stimulation energy to contract the multifidus muscle. In some embodiments, stimulation elements  260  are configured to stimulate tissue by providing episodic electrical stimulation. In some embodiments, apparatus  10  comprises a tool  60  configured to diagnose a defect in spinal muscle or the motor control system. In some embodiments, apparatus  10  comprises a tool  60  configured to test function of the multifidus muscle, such as when tool  60  comprises an MRI; ultrasound imager; electromyogram; tissue biopsy device; and/or a device configured to test displacement as a function of load for a spine. 
     In some embodiments, two or more external system  50  components are connected by a connecting filament, such as is described hereabove. Alternatively or additionally, two or more implantable system  20  components are connected by a conduit, such as a connecting filament as described herein. Alternatively or additionally, two more external system  50  components and/or two or more implantable system  20  components transmit information and/or power via a wireless transmitter (e.g. an RF transmitter), magnetic coupling, inductive coupling, capacitive coupling and/or other wireless transmission means. 
     Apparatus  10  can include one or more devices, such as patient attachment device  70  shown in  FIG. 1 , that is used to attach one or more portions of external system  50  to a location on or proximate the patient. In some embodiments, patient attachment device  70  is constructed and arranged as described in applicant&#39;s co-pending U.S. patent application Ser. No. 15/385,729, titled “Method and Apparatus for Neuromodulation Treatments of Pain and Other Conditions”, filed Dec. 20, 2016. 
     Patient attachment device  70  can comprise one or more elements configured to attach one or more external devices  500  and/or programmer  550  at one or more locations on or proximate the patient&#39;s skin, that are relatively close to one or more implantable devices  200 / 800  that have been implanted in the patient. Patient attachment device  70  can comprise a component selected from the group consisting of: belt; belt with pockets; belt with adhesive, adhesive; strap; strap with pockets; strap with adhesive shoulder strap; shoulder band; shirt; shirt with pockets; clothing; clothing with pockets; epidural electronics packaging; clip; bracelet; wrist band; wrist watch; anklet; ankle bracelet; knee strap; knee band; thigh strap; thigh band; necklace; hat; headband; collar; glasses; goggles; earpiece; behind-the-earpiece; and combinations of one or more of these. In some embodiments, patient attachment device  70  comprises a belt configured to surround at least one antenna  540  (e.g. at least one antenna  540   a  and/or  540   b  mounted to or otherwise positioned on a printed circuit board such as a flexible printed circuit board). Patient attachment device  70  can include one or more pockets, such as one or more pockets configured to collectively surround one or more of: external device  500 ; programmer  550 ; one or more antennas  540 ; power supply  570 ; power supply  557 ; and combinations of one or more of these. In some embodiments, patient attachment device  70  comprises multiple pockets, such as to allow repositioning of an external antenna  540 , programmer  550 , external transmitter  530 , power supply  570 , and/or power supply  557  to various different locations, such as to improve transmission of power and/or data to one or more implantable devices  200 / 800  and/or to improve patient comfort. In some embodiments, one or more antennas  540 , power supplies  570 , power supplies  557 , transmitters  530 , and/or transmitters  553  are connected through flexible cables positioned in patient attachment device  70 . In some embodiments, the flexible cables are small coax cables that can accommodate the power levels and frequencies of the carried signals. In some embodiments, the one or more antennas  540  are connected to one or more additional components of external device  500  and/or programmer  550  through a single cable with a local power splitting component and/or active matching element that adjusts signal power to each of the one or more antennas  540 . 
     In some embodiments, one or more implantable devices  200 / 800  of implantable system  20  can comprise an implantable transmitter configured to transmit data, such as to transmit data (e.g. stimulation information, patient physiologic information, patient environment information, implantable device  200 / 800  performance and/or configuration information, and the like) to one or more external devices  500  and/or programmer  550 . In these embodiments, receiver  230 / 830  can be configured as both a receiver and a transmitter. One or more implantable devices  200 / 800  can be configured to transmit data by sending a signal to (i.e. “driving”) one or more antennas  240 / 840  or another antenna of implantable device  200 / 800 . An implantable device  200 / 800  can be configured to transmit data using one or more of: load modulation; a signal carrier; and/or body conduction. An implantable device  200 / 800  can be configured to adjust the transmission, such as to adjust a data transmission parameter selected from the group consisting of: data rate; pulse width; duration of carrier signal; amplitude of carrier signal; frequency of carrier signal; configurable load; and combinations of one or more of these. 
     In some embodiments, apparatus  10  comprises a diagnostic assembly, diagnostic assembly  91  shown in  FIG. 1 . In some embodiments, programmer  550  and/or implantable controller  250 / 850  comprise all or a portion of diagnostic assembly  91 . Diagnostic assembly  91  can be configured to assess, monitor, determine and/or otherwise analyze patient information and/or implantable device  200 / 800  information, such as when one or more stimulation elements  260  or functional elements  299 / 599 / 899  are configured as a sensor that records patient information (e.g. patient physiologic information and/or patient environment information) and/or apparatus  10  information (e.g. implantable device  200 / 800  information) as described herein. Diagnostic assembly  91  can be configured to analyze communication and/or the power link between an implantable device  200 / 800  and an external device  500 . In some embodiments, such a communication link analysis can be performed by measuring bit error rate (BER) of a known data stream during communication signal transmission (also referred to as “communication link”) measurement phase (e.g. such as during a calibration procedure). The BER can be tracked by the controller  250 / 850  or programmer  550 , such as to monitor and keep track of any trends in the link. This trend can be used to adjust the link and/or provide feedback to an operator of apparatus  10  (e.g. the patient), in case the link cannot be automatically adjusted to compensate for a negative trend (e.g. such that the operator can perform physical re-adjustment of the external system  50 ). Alternatively or additionally, a power link analysis can be performed by monitoring charge/discharge rate of the implanted energy storage assembly  270 / 870 . Similar to the communication link, the power link status and/or trending can be monitored and recorded for link adjustment and/or feedback purposes. Diagnostic assembly  91  can be configured to analyze a result of stimulation energy delivered by implantable device  200 / 800 , such as when a stimulation element  260  comprises an electrode to record electrical activity of tissue (e.g. in addition to delivering electrical energy to stimulate tissue). A stimulation element  260  and/or functional element  299 / 599 / 899  can comprise a sensor configured to record neural activity and/or muscular activity, and diagnostic assembly  91  can be configured to analyze the recorded sensor data. In some embodiments, diagnostic assembly  91  can be configured to analyze impedance, such as when a stimulation element  260  and/or a functional element  299 / 599 / 899  comprises a sensor configured to record data related to impedance, such as when implantable device  200 / 800  performs a frequency sweep, performs an impulse response and/or compares voltage and current of a stimulation waveform. In some embodiments, diagnostic assembly  91  is configured to assess the impedance of one or more implantable antennas  240 / 840  and/or one or more external antennas  540 . In these embodiments, impedance can be assessed by performing a function selected from the group consisting of: performing a frequency sweep; performing an impulse response; comparing voltage and current of a waveform; and combinations of one or more of these. 
     In some embodiments, diagnostic assembly  91  is configured to test or otherwise assess the link between one or more implantable antennas  240 / 840  and one or more external antennas  540  (e.g. during a procedure in which one or more implantable devices  200 / 800  are implanted in a patient). In these embodiments, diagnostic assembly  91  can be configured to perform a test prior to anchoring housing  210 / 810  to tissue (e.g. prior to initial or final suturing into tissue such as the fascia layer). For example, lead  265  can be implanted at a location to stimulate target tissue (e.g. one or more nerves identified to treat pain or another patient condition). Prior to suturing housing  210 / 810  in its implant location, diagnostic assembly  91  can be configured to confirm that one or more external antenna  540  transmission links to one or more implantable antennas  240 / 840  are above an efficiency threshold, for example such that sufficient power will be received by the one or more implantable devices  200 / 800 . Additionally, the procedure can be performed to optimize or otherwise improve the position of the one or more implantable devices  200 / 800  to be implanted and subsequently secured to tissue. 
     In these link testing embodiments, diagnostic assembly  91  can comprise a handheld assembly (e.g. a sterile assembly comprising a wand or other handheld housing). Diagnostic assembly  91  can be configured to send a simple signal to one or more implantable devices  200 / 800  (e.g. a diagnostic assembly  91  with similar power and/or data transmission capabilities as an external device  500 ). Each implantable device  200 / 800  can respond (e.g. via data sent via an implantable antenna  240 / 840  or other transmitter) with information related to the quality of the transmission link (e.g. information about the power received by the one or more implantable devices  200 / 800 ). Diagnostic assembly  91  could provide a user interface (e.g. a speaker, a text screen and/or a video display) that provides quality or other information (go/no go information, digital or other discrete level information, and/or analog information). Diagnostic assembly  91  could be further configured to provide information confirming detection of one or more implantable devices  200 / 800 , status of one or more implantable devices  200 / 800  (e.g. parameter level and/or fault detection status), and/or self-diagnostic status (i.e. diagnostic assembly  91  status). 
     Each implantable device  200 / 800  can be configured to specifically identify and/or specifically reply to diagnostic assembly  91  (e.g. in a different form than communications with an external device  500 ). Each implantable device  200 / 800  can be configured to provide information related to one or more of: the charge and/or discharge rate of energy storage assembly  270 / 870  (e.g. the charge and/or discharge rate of a capacitor or battery of energy storage assembly  270 / 870 ); or the frequency of a voltage-controlled oscillator that is driven by an unregulated voltage of a power converter of receiver  230 / 830 . Diagnostic assembly  91  can be configured to perform numerous performance tests (e.g. of one or more implantable devices  200 / 800  or implantation locations for one or more implantable devices  200 / 800 ), prior to completion of the implantation procedure (e.g. prior to closing one or more incisions). 
     In some embodiments, implantable system  20  of apparatus  10  is configured to perform magnetic field modulation, such as targeted magnetic field neuromodulation (TMFN), electro-magnetic field neuromodulation, such as targeted electro-magnetic field neuromodulation (TEMFN), transcutaneous magnetic field stimulation (TMS), or any combination of these. Each implantable device  200 / 800 , via one or more of its stimulation elements  260  (e.g. electrodes) can be configured to provide localized (e.g. targeted) magnetic and/or electrical stimulation. Combined electrical field stimulation and magnetic field stimulation can be applied by using superposition, and can reduce the overall energy requirement. In some embodiments, implantable apparatus  10  comprises one or more stimulation elements  260  comprising a magnetic field generating transducer (e.g. microcoils or cuff electrodes positioned to partially surround or otherwise be proximate to one or more target nerves). Stimulation elements  260  comprising microcoils can be aligned with nerves to minimize affecting non-targeted tissue (e.g. to avoid one or more undesired effects to non-target tissue surrounding or otherwise proximate the target tissue). In some embodiments, the target tissue comprises dorsal root ganglia (DRG) tissue, and the non-target tissue comprises ventral root tissue (e.g. when the stimulation energy is below a threshold that would result in ventral root tissue stimulation). 
     In some embodiments, external system  50  of apparatus  10  is configured to provide mechanically adjustable alignment of one or more external antennas  540  alignment. Link gain between one or more external antennas  540  and one or more implantable antennas  240 / 840  can degrade over time due to physical misalignment of the antennas, relative orientation change between antennas and/or relative angular misalignment between antennas. In order to compensate for misaligned antennas, electrical beam steering can be included in apparatus  10 . Antennas comprising a multi-feed antenna structure and/or an array of antennas can be incorporated (e.g. into external antenna  540 , implantable antenna  240 / 840  or both) for electrical beam steering. Alternatively or additionally, mechanical antenna steering can be implemented to physically realign one or more external antennas  540  with one or more implanted antennas  240 / 840  (or vice versa). A substrate of an implantable antenna  240 / 840  and/or an external antenna  540  can be flexible and/or rigid (e.g. a substrate comprising polyamide, polyimide, liquid crystal polymer (LCP), Rogers, FR4, or a similar material). One or more antennas  540  can be connected to electronics (e.g. a transmitter, receiver or transceiver) using a flexible waveguide or cable (e.g. 50 ohm 0.047″ coaxial cable designed to provide patient comfort) and/or a flexible PCB substrate transmission line. Mechanical or physical realignment of antennas  240 / 840  and/or  540  can be accomplished using one or more of: use of motorized positioners, such as a mechanism including one or more small pulleys and/or tensioners used to translate one or more antennas  240 / 840  and/or  540  about one or more axes; an actuator (e.g. a piezoelectric actuator) with directional gears configured to translate one or more antennas  240 / 840  and/or  540  about one or more axes; a micro-pump with fluid reservoir (e.g. liquid or gas reservoir) configured to hydraulically and/or pneumatically translate one or more antennas  240 / 840  and/or  540  about one or more axes, such as by creating a local pressure difference. In some embodiments, a micro-pump with fluid reservoir can be used to move one or more antennas  240 / 840  and/or  540 , such as to move an external antenna  540  away from tissue to reduce specific absorption rate (SAR). In these embodiments, external antenna  540  can be positioned in mechanical contact with an expandable reservoir (e.g. a balloon) positioned between external antenna  540  and tissue. The reservoir can be inflated or deflated to control separation distance of the external antenna  540  from the patient&#39;s skin surface. In some embodiments, apparatus  10  comprises one or more algorithm positioning algorithms, beam steering functionality and/or mechanical antenna steering as described in applicant&#39;s co-pending U.S. patent application Ser. No. 14/975,358, titled “Method and Apparatus for Minimally Invasive Implantable Modulators”, filed Dec. 18, 2015, or International PCT Patent Application Serial Number PCT/US2016/016888, titled “Medical Apparatus including an Implantable System and an External System”, filed Feb. 5, 2016, the content of each of which is incorporated herein in its entirety for all purposes. 
     In some embodiments, implantable system  20  of apparatus  10  is configured to provide paresthesia-reduced (e.g. paresthesia-free) high frequency pain management and rehabilitation therapy (e.g. via delivery of a stimulation signal above 600 Hz or 1 kHz, or other stimulation signal resulting in minimal paresthesia). Apparatus  10  can be configured to provide both low frequency (e.g. &lt;1 kHz) stimulation and high frequency stimulation, such as when providing low frequency stimulation to elicit feedback from a patient during intraoperative or other (e.g. post-implantation) stimulation configuration. For example, programmer  550  and/or an external device  500  can be used during an intra-operative titration of stimulation configuration using low frequency stimulation (e.g. to position and/or confirm position of one or more stimulation elements  260 , such as to confirm sufficient proximity to target tissue to be stimulated and/or sufficient distance from non-target tissue not to be stimulated). In some embodiments, high frequency stimulation is delivered to reduce pain over extended periods of time, and low frequency stimulation is used in these intraoperative and/or post-implantation titration or other stimulation configuration procedures. Intentional elicitation of paresthesia (e.g. via low frequency stimulation and/or high frequency stimulation) is beneficial during stimulation element  260  (e.g. electrode) implantation because a patient can provide feedback to the implanting clinician to ensure that the stimulation elements  260  are positioned close to the target neuromodulation or energy delivery site. This implantation position-optimizing procedure can advantageously reduce the required stimulation energy due to stimulation elements  260  being closer to target tissue, since a minimum threshold for efficacious stimulation amplitude is proportional to the proximity of stimulation elements  260  to target tissue (e.g. target nerves). The patient can inform the clinician of the sensation of paresthesia coverage, and the clinician can adjust stimulation element  260  position to optimize stimulation element  260  location for efficacious treatment while minimizing unintentional stimulation of non-target tissue (e.g. motor nerves or other nerves which are not causing the patient&#39;s pain). These paresthesia-inducing techniques (e.g. using low frequency stimulation and/or high frequency stimulation) can be used during or after implantation of one or more implantable devices  200 / 800 . 
     In some embodiments, apparatus  10  is configured to deliver low frequency stimulation energy (e.g. electrical energy comprising a low frequency signal provided by implantable device  200  and/or implantable device  800 ) to stimulate motor nerves, such as to improve tone and structural support (e.g. physical therapy). In these embodiments, apparatus  10  can be further configured to provide high frequency stimulation, such as to treat pain (e.g. suppress and/or control pain). The combined effect can be used not only for pain management but also muscle strengthening and gradual healing of supportive structures. Alternatively or additionally, as described herein, apparatus  10  can be configured to deliver low frequency stimulation energy (e.g. electrical energy) to induce paresthesia, which can also be accompanied by the delivery of high frequency stimulation (e.g. to suppress and/or control pain). In some embodiments, apparatus  10  is configured to deliver low frequency stimulation (e.g. electrical energy comprising a low frequency signal) and burst stimulation, delivered simultaneously or sequentially. The low frequency stimulation and the burst stimulation can be delivered on similar and/or dissimilar stimulation elements  260  (e.g. similar or dissimilar electrode-based stimulation elements  260 ). 
     Apparatus  10  can be configured to treat neuropathy, neuralgia and/or other nerve pain that is related to: surgery; trauma; infection (e.g. a herpetic infection); and/or diabetes (e.g. diabetic neuropathy). One or more stimulation elements  260  can be configured to deliver stimulation energy (e.g. electrical energy, magnetic energy, light energy, thermal energy, sound energy, and/or chemical energy (e.g. energy from a drug or reagent) to nerve tissue such as tissue of the central nervous system and/or peripheral nervous system. One or more leads  265  (each comprising one or more stimulation elements  260 ) can be implanted in and/or proximate the spinal cord, the groin and/or a joint such as the hip. For example, apparatus  10  can be configured to treat one or more of post-surgical neuralgia (e.g. following hernia repair such as a hernia repair including an implanted mesh); headache (e.g. due to occipital neuralgia); post-herpetic neuralgia; chronic pelvic and/or hip pain; knee pain; and combinations of one or more of these. 
     To treat pain related to hernia or hernia repair, one or more stimulation elements  260  (e.g. on a lead  265  and/or on a housing  210 ) can be positioned to stimulate tissue of the peripheral nervous system and/or the central nervous system. In some embodiments, one or more stimulation elements  260  are positioned to stimulate the cutaneous branch of the ilioinguinal, inguinal and/or genital branch of the genitofemoral nerves. In some embodiments, one or more stimulation elements  260  are positioned to stimulate corresponding branches of spinal nerves correlating to one or more dermatomes related to pain associated with at least one of hernia or hernia repair. Hernia or hernia repair can lead to: inguinal pain; ilioinguinal neuralgia; post-traumatic neuropathic pain; ilioinguinal nerve entrapment; neuropathic pain of ilioinguinal origin; post-surgical inguinal pain; genitofemoral pain; genitofemoral neuralgia; genitofemoral nerve entrapment; neuropathic pain of genitofemoral origin; post-surgical genitofemoral pain; iliohypogastric pain; iliohypogastric neuralgia; iliohypogastric nerve entrapment; neuropathic pain of iliohypogastric origin; post-surgical iliohypogastric pain; testicular pain; scrotal pain; penis pain; groin pain; thigh pain; anal pain; rectal pain; perineal pain; abdominal adhesions; pelvic adhesions; scar pain; diffuse polyneuropathy; and combinations of one or more of these. In some embodiments, apparatus  10  is configured to treat hernia pain by delivering a low frequency stimulation signal (e.g. an electrical signal less than or equal to 1 kHz delivered by one or more electrode-based stimulation elements  260 ). Alternatively or additionally, apparatus  10  can treat hernia pain with a high frequency stimulation signal, such as a signal comprising a frequency greater than 1 kHz. Stimulation can be accomplished either via subcutaneous field stimulation and/or by stimulation elements  260  positioned adjacent or at least near the nerves and/or their branches. In some embodiments, stimulation is accomplished transvascularly (e.g. stimulation including low and/or high frequencies). 
     The apparatus of the present inventive concepts can be configured to stimulate the ilioinguinal nerve, genitofemoral nerve and/or iliohypogastric nerves, such as to ameliorate pain following hernia repair. One or more leads  265  (e.g. one or more leads  265  comprising one or more electrode-based or otherwise stimulation-based stimulation elements  260 ) can be inserted over the inguinal region (which may include the inguinal ring) to stimulate any or all three of these nerves (e.g. in a unilateral or bilateral fashion). Both the ilioinguinal and genital branch of the genitofemoral nerves pass through the inguinal ring. The anterior cutaneous iliohypogastric and femoral branch of the genitofemoral nerve can be stimulated at one or more locations proximate but rostral (iliohypogastric) or lateral (genitofemoral) to the inguinal ring. Leads  265  can comprise one or more stimulation elements  260  comprising cylindrical, paddle, cuff and/or hemi-cuff electrodes (electrodes placed surgically near and/or around these nerves). The nerves can be localized via ultrasound or other imaging modalities. Contrast can be used to image the vessels nearby (e.g. the testicular and/or ovarian vein and/or artery). The genital branch of the genitofemoral nerve can be stimulated in a transvascular manner through the testicular vein and/or artery. The genitofemoral and/or the ilioinguinal nerves can also be stimulated (e.g. transvascularly stimulated) through the femoral vein and/or artery, or via the superficial or deep external pudendal vein and/or artery, and/or via the superficial epigastric vein and/or artery. 
     The painful areas innervated by the ilioinguinal nerve, genitofemoral nerve and/or iliohypogastric nerves, can also be treated via spinal cord stimulation provided by apparatus  10  in the L1-L5 region of the spinal cord. In some embodiments, direct stimulation of the L1-L2 dorsal root ganglia is provided in a similar treatment. Leads  265  (e.g. percutaneous or paddle) including stimulation-based stimulation elements  260  can be placed over the dorsal columns, over the dorsal roots and/or in the dorsal root entry zone, in a unilateral, bilateral and/or midline fashion. 
     To treat occipital neuralgia, also known as C2 neuralgia, one or more stimulation elements  260  can be positioned to stimulate peripheral nerve tissue to reduce pain. Occipital neuralgia is a medical condition characterized by chronic pain in the upper neck, back of the head and/or behind the eyes (areas corresponding to the locations of the lesser and greater occipital nerves). In some embodiments, one or more leads  265 , each comprising one or more stimulation elements  260 , can be implanted transversely, either unilaterally or bilaterally, at the level of the appropriate target cervical nerve (C1, C2, etc.). The C1, C2, C3 cervical roots include the greater occipital nerve which originates primarily from C2, and the lesser occipital nerves. Relevant trigeminal branches include both the supraorbital and supratrochlear nerves from V1, the infraorbital branches from V2, and the superficial temporal nerves from V3. A partial convergence of these two systems occurs at the Trigemino-Cervical Complex (TCC). In some embodiments, one or more stimulation elements  260  are positioned to stimulate the trigeminal and/or occipital nerves. One or more leads  265  can be anchored to the fascia proximate the tissue to be stimulated. 
     To treat post-herpetic neuralgia (e.g. neuralgia associated with shingles), one or more stimulation elements  260  can be positioned to stimulate corresponding branches of the spinal nerves correlating to one or more dermatomes related to the patient&#39;s shingles. 
     In some embodiments, apparatus  10  is configured to treat pelvic, bladder and/or bowel disorders, such as by stimulating sacral, pudendal and/or tibial nerves. In some embodiments, apparatus  10  is configured to treat pelvic pain by stimulating the tibial nerve. 
     Apparatus  10  can be configured to treat a bladder, bowel or other dysfunction selected from the group consisting of: overactive bladder; urinary urgency; urinary frequency; urinary urgency frequency; urinary urge incontinence; urinary stress incontinence; urge incontinence; stress incontinence; non-obstructive urinary retention; female sexual dysfunction; fecal incontinence; constipation; diarrhea; irritable bowel syndrome; colitis; detrusor instability; detrusor dysfunction; spastic bladder; neurogenic bladder; detrusor sphincter dyssynergia; detrusor hyperreflexia; detrusor areflexia; and combinations of one or more of these. 
     Apparatus  10  can be configured to treat a pelvic disorder selected from the group consisting of pelvic pain; painful bladder syndrome; Hunner&#39;s ulcers or lesions; interstitial cystitis; pelvic floor dysfunction; endometriosis; vulvodynia; dyspareunia; pelvic adhesions; abdominal adhesions; irritable bowel syndrome; pelvic girdle pain; pudendal nerve entrapment; pudendal neuralgia; dysmenorrhea; Müllerian abnormalities; pelvic inflammatory disease; ovarian cysts; ovarian torsion; Loin pain hematuria syndrome; proctitis; prostatitis; prostadynia; post-abdominal surgical pain; post-pelvic surgical pain; hernia pain; post-hernia surgical pain; anal pain; rectal pain; perineal pain; groin pain; vulvar pain; vaginal pain; clitoral pain; colitis; and combinations of one or more of these. 
     Apparatus  10  can be configured to treat one or more of the pelvic disorders, bladder dysfunctions and/or and bowel dysfunctions listed above, by stimulating (e.g. using bilateral and/or unilateral stimulation) one or more of the targets listed below. 
     In some embodiments, the stimulated targets include the sacral nerves (roots) S2, S3 and/or S4. One or more leads  265  (e.g. each including one or more stimulation-delivering stimulation elements  260 ) can be positioned to stimulate any or all of the three roots, on a single side or both sides, in any bilateral or unilateral combination. The roots can be accessed, with the patient lying in the prone position, by positioning one or more leads  265  (e.g. percutaneously), with or without the use of fluoroscopy, ultrasound or any other imaging modality, into one/any of the sacral foramen(a) from the posterior aspect of the sacrum. One or more leads  265  can be passed through the foramen to the anterior side of the sacrum, and/or one or more leads  265  can remain inside the foramen(a). 
     In some embodiments, the sacral roots are approached rostrally, via the sacral canal in a retrograde manner. In these embodiments, one or more leads  265  can be passed through the ligamentum flavum, just caudal to L5 or via any of the intervertebral spaces from L5 to T12, into the spinal canal. One or more leads  265  are then threaded, with or without the aid of visualization (fluoroscopy, ultrasound or other imaging modality), in a caudal (retrograde) manner to enter the sacral canal. One or more leads  265  can be placed along the sacral canal, and each root can be stimulated individually and/or each root can be stimulated in concert, via one or more leads  265  positioned along the internal surface of the sacral canal, and spanning one or more foramina. 
     In some embodiments, one or more leads  265  are threaded from the spinal canal into each and/or all sacral foramen(a), in an anterior direction. The sacral canal can also be accessed caudally by one or more leads  265 , via the sacral hiatus in an anterograde manner. 
     In some embodiments, the sacral roots (S2, S3 and/or S4) are accessed as they enter the spinal cord at the cauda equina. This access can be achieved by inserting the one or more leads  265  through the ligamentum flavum, at a location just caudal to L5, or via any of the intervertebral spaces from L5 to T12, into the spinal canal. The one or more leads  265  can then be threaded, with or without the aid of visualization (fluoroscopy, ultrasound or other imaging modality), up to the cauda equina, where the S2, S3 and/or S4 roots can be stimulated where they enter the spinal cord, and/or the conus medullaris can be stimulated directly (e.g. in the same location). 
     In some embodiments, the pudendal nerve is stimulated through one or more different approaches. The pudendal nerve contains both afferent and efferent fibers carried by S2, S3 and S4 roots. The pudendal fibers exit Alcock&#39;s canal near the ischial spine, where they spread out to innervate to the bladder wall, perineum, anus, genitals and urethra. Pelvic and voiding disorders can be treated by stimulating pudendal nerve fibers. The fibers can be accessed at the Alcock&#39;s canal via various approaches. In one embodiment, a transperineal approach is achieved by positioning the patient in the lithotomy position and inserting the lead  265  midpoint between the ischial tuberosity and the anus. A lead  265  is inserted toward the ischial spine, which can be palpated transvaginally or transrectally. The ischial spine can also be visualized through a number of imaging modalities (e.g. fluoroscopy, x-ray, ultrasound, and the like). In another embodiment, a transvaginal approach is achieved by positioning the patient in the lithotomy position and inserting a lead  265  through the vaginal wall, adjacent to the ischial spine (e.g. through the vaginal wall toward the ischial spine). In another embodiment, a posterior approach is achieved by laying the patient in the prone position and inserting a lead  265  just medial to the ischial tuberosity toward the ischial spine. This insertion can be facilitated by rectal palpation of the ischial spine and through visualization via a number of imaging modalities (e.g. fluoroscopy, x-ray, ultrasound, and the like). 
     In some embodiments, apparatus  10  is configured to stimulate pudendal afferents, such as by stimulating the dorsal genital nerve. These fibers are located just below the skin on the dorsum of the penis or just rostral to the clitoris. In some embodiments, pudendal afferents are stimulated periurethrally. One or more leads  265  can be inserted alongside the urethra to stimulate the pudendal fibers. 
     In some embodiments, apparatus  10  is configured to stimulate tibial nerve fibers, such as to treat one or more pelvic disorders (e.g. voiding dysfunction). The tibial nerve can be accessed a few mm below the skin surface in the ankle immediately posterior to the medial malleolus. Lead  265  can comprise a cylindrical SCS-type lead, which can be inserted percutaneously in this location. Alternatively or additionally, a direct (surgical) cut-down can be used to insert a cylindrical lead or to apply a cuff electrode directly to the nerve. The tibial nerve can also be accessed approximately half way up the lower leg adjacent to the tibia. One or more leads  265  can be inserted percutaneously in this location. Alternatively or additionally, a direct cut-down can be used to insert lead  265  (e.g. a cylindrical lead or a cuff electrode and/or hemi-cuff electrode applied directly to the nerve in the mid-shin location). Tibial nerve fibers can be accessed in the popliteal fossa behind the knee, for example percutaneously with a lead  265  comprising a cylindrical lead, and/or via a direct cut-down, for example with a lead  265  comprising either a cylindrical or cuff electrode. 
     In some embodiments, apparatus  10  and one or more leads  265  are constructed and arranged to stimulate the tibial and/or pudendal nerves via a transvascular approach (i.e. stimulation energy delivered from inside a blood vessel to nerve tissue proximate the blood vessel), such as via the femoral vein and/or artery, each of which provide intraluminal access to many other blood vessels (e.g. using standard interventional techniques). The tibial nerve can be transvascularly stimulated by the popliteal vein and/or artery (e.g. by placing one or more stimulation elements  260  in the popliteal vein and/or artery), at a location behind the knee. The popliteal vein and/or artery can be intraluminally accessed from the femoral artery and vein. The tibial nerve also passes near the small saphenous vein, where it branches off of the popliteal vein. The posterior tibial vein and/or artery are positioned adjacent to the tibial nerve, from the knee to the foot. One or more leads  265  can utilize one or more of these above locations to stimulate the tibial nerve. 
     In some embodiments, apparatus  10  and one or more leads  265  are constructed and arranged to stimulate the pudendal nerve and/or sacral roots, such as using a lead  265  placed via the femoral vein and/or artery, which in turn provides intraluminal access to many vessels. One or more leads  265  can be configured to utilize any of the following arteries and veins to stimulate the pudendal nerve and/or the sacral roots. One or more leads  265  can be constructed and arranged to stimulate a target site via a blood vessel selected from the group consisting of: the internal pudendal artery or vein (which branch off of common iliac artery or vein, respectively); the inferior and superior gluteal vein and/or artery; middle rectal, pudendal plexus and internal iliac vein and/or artery; medial and lateral sacral vein and/or artery; uterine and obturator vein and/or artery; and combinations of one or more of these. 
     In some embodiments, apparatus  10  is configured to treat pelvic dysfunction, overactive bladder, and/or urinary incontinence (singly or collectively “overactive bladder” herein). In some embodiments, apparatus  10  is configured to treat overactive bladder such as to reduce the effects of overactive bladder and/or to decrease use of one or more medications taken by the patient to treat overactive bladder. In some embodiments, one or more stimulation elements  260  are positioned to stimulate tissue of the central nervous system or tissue and/or tissue of the peripheral nervous system to treat overactive bladder, such as to stimulate one or more nerves that control and/or are otherwise related to bladder function (e.g. to increase bladder capacity, improve bladder emptying, reduce urge incontinence and/or reduce stress incontinence). For example, one or more stimulation elements  260  can be positioned to stimulate tibial nerve tissue and/or sacral nerve tissue (e.g. at least the S3 nerve root) to treat overactive bladder. In some embodiments, lead  265  is constructed and arranged to be positioned along one or more locations of the tibial nerve, such as a positioning performed using percutaneous technique (e.g. when lead  265  comprises a cylindrical SCS-type lead) and/or surgical (cut-down) techniques (e.g. when lead  265  comprise a cuff electrode and/or hemi-cuff electrode applied directly to the nerve). The tibial nerve branches off of the sciatic nerve just above the knee, and runs along the length of the tibia, medial and lateral to the tibia. The tibial nerve then passes posterior to the medial malleolus prior to innervating the plantar surface of the foot. Lead  265  can be constructed and arranged to access sites proximate the tibial nerve percutaneously and/or through an incision at the back of the knee in the popliteal fossa, along the tibia or behind the medial malleolus. The housing  210 / 810  can be placed anywhere in the leg when stimulating the tibial nerve. Lead  265  can be constructed and arranged to stimulate the tibial nerve through a transvascular approach, via the femoral vein and/or artery, each of which provide intraluminal access to many vessels. The tibial nerve can be accessed by the popliteal artery and vein behind the knee, which are intraluminally accessible from the femoral artery and vein, respectively. The tibial nerve also passes near the small saphenous vein, where it branches off of the popliteal vein. The posterior tibial vein and artery travel adjacent to the tibial nerve from the knee to the foot. One or more leads  265  can be constructed and arranged to utilize any of these locations to transvascularly stimulate the tibial nerve (e.g. transvascularly stimulate the tibial nerve via the popliteal artery, popliteal vein, saphenous vein, posterior tibial artery and/or posterior tibial vein via a lead  265  advanced via the femoral vein and/or artery). In these transvascular embodiments, the housing  210 / 810  can be placed near the femoral or popliteal access point at locations in the groin, perineum, scrotum, pelvis, hip, thigh, leg, behind the knee, buttocks, abdomen and/or low back. In the case of sacral nerve stimulation, one or more leads  265  can be inserted through an incision(s) made in the lower back, such that one or more stimulation elements  260  are positioned proximate (e.g. in contact) with the sacral nerve root(s). The housing  210 / 810  can be placed anywhere in the groin, perineum, scrotum, pelvis, hip, thigh, leg, behind the knee, buttocks, abdomen and/or low back. Lead  265  (e.g. a lead  265  comprising a lead extension) can be extended underneath the skin (e.g. tunneled) to a second incision (e.g. across the flank to the lower abdomen, across the midline to the buttocks, or low back), and a third incision can be made (e.g. in the abdomen, back or buttocks) where housing  210 / 810  can be inserted and connected to lead  265  (e.g. via port  290 / 890  as described herein). Alternatively, housing  210 / 810  can be inserted at another internal location. If lead  265  is already connected (e.g. attached in manufacturing) to housing  210 / 810 , lead  265  can be advanced in the opposite direction, such as from the third incision, to the second incision, to the first incision (if three incisions are made), or housing  210 / 810  can be advanced under the tissue from incision  1  to incision  2  or from incision  2  to incision  3 . In some embodiments, only 1 or 2 incisions are performed. In some embodiments, such as when lead  265  is already connected (e.g. attached in manufacturing) to housing  210 , lead  265  and housing  210 / 810  are implanted. In some embodiments, a first lead  265  and a first housing  210 / 810  (pre-attached or attachable) are utilized in a dose titration or other “trialing procedure” (e.g. during a trial period of the present inventive concepts), and a second lead  265  and housing  210 / 810  (pre-attached or attachable) are implanted in the patient for subsequent treatment of the patient (e.g. during a therapy period of the present inventive concepts). 
     In some embodiments, one or more stimulation elements  260  are positioned to perform posterior tibial nerve stimulation (PTNS), also referred to as percutaneous tibial nerve stimulation, such as to perform an indirect form of neuromodulation to treat bladder voiding dysfunction. The posterior tibial nerve is derived from the lumbar-sacral nerves (L4-S3), which innervate the bladder detrusor and pelvic floor. In some embodiments, one or more stimulation elements  260  can be positioned to perform retrograde stimulation of the sacral nerve plexus and restore the balance between bladder inhibitory and excitatory control systems of the bladder. One or more stimulation elements  260  can be positioned above the ankle, proximate and/or into the tibial nerve. Implantable device  200 / 800  can deliver stimulation energy to the stimulation elements  260  comprising low-voltage electrical stimulation configured to produce sensor and/or motor responses. Apparatus  10  can be configured to provide continuous and/or intermittent stimulation to tissue, such as to modulate transmission of excitatory nerve signals to the bladder muscles. In some embodiments, implantable system  20  is configured to deliver a series of repeated stimulation periods, such as a regimen of approximately weekly thirty minute sessions of stimulation for twelve weeks. In some embodiments, implantable system  20  is configured to provide daily or hourly sessions that deliver stimulation for between 10 minutes and 60 minutes. In some embodiments, apparatus  10  is configured to achieve an approximate 50% reduction in urinary urge incontinence and/or urinary urgency/frequency episodes. 
     In some embodiments, apparatus  10  is configured to provide temporary stimulation therapy of tissue to treat overactive bladder, such as by using one or more external devices  500 , such as to provide power and/or data to one or more implantable devices  200 / 800  to confirm acceptable improvement of the patient&#39;s overactive bladder (e.g. successful stimulation of one or more sacral nerves, tibial nerves or other tissue), before closing an incision or otherwise fully implanting one or more implantable devices  200 / 800 . In some embodiments, a temporary stimulation therapy is provided for: up to one week, up to one month, more than 1 month, more than 2 months, or more than 3 months. In some embodiments, one or more implantable devices  200 / 800  are left in place if the temporary stimulation therapy period is successful or unsuccessful (e.g. left implanted due to its small size or otherwise minimal impact on the patient). 
     In some embodiments, apparatus  10  is configured to stimulate a region of the pelvic floor, such as to: change the reflex thresholds of the bladder muscles responsible for bladder emptying, strengthen and/or otherwise improve the condition of the muscles that maintain closure on the bladder outlet; change the state of the neural pathways, musculature and/or bladder during and beyond the period stimulation; and/or otherwise decrease the severity of urinary incontinence. In some embodiments, one or more stimulation elements  260  are positioned to stimulate periurethral muscles. In some embodiments, one or more stimulation elements  260  are positioned to stimulate tissue of the vagina or anus. In some embodiments, one or more stimulation elements  260  are positioned to stimulate sphincter muscles for controlling the bladder, such as two stimulation elements  260  positioned on either side of the urethral orifice. In these embodiments, housing  210 / 810  can be implanted in suprapubic region or in the perineum. In some embodiments, lead  265  comprises (e.g. on a distal portion) a pessary ring comprising two stimulation elements  260 . In some embodiments, stimulation elements  260  comprise periurethral electrodes configured to stimulate pudendal afferents. 
     As described above, apparatus  10  can be configured for treating numerous diseases, disorders or other undesirable patient conditions, such as fecal incontinence. Injury of nerves that sense stool in the rectum can lead to fecal incontinence. In some embodiments, one or more stimulation elements  260  (e.g. one or more electrical, magnetic, light or other energy delivery elements) of one or more leads  265  and/or one or more implantable devices  200 / 800  are configured to stimulate tissue to treat fecal incontinence, such as to treat tissue selected from the group consisting of: sacral nerve tissue; tissue whose stimulation strengthens muscles of the bowel and/or rectum; and combinations of one or more of these. In these fecal incontinence applications, leads  265  can be implanted in a location selected from the group consisting of: the pelvic girdle; the sacral foramina; the lower back; the upper buttock; and combinations of one or more of these, such as to stimulate sacral nerve tissue. Leads  265  can be anchored via lead anchors (silicone or other materials), suture, staples, clips, adhesive and the like, such as an attachment to the underlying fascia of target tissue to be stimulated. In some embodiments, apparatus  10  is configured to treat both fecal incontinence and a bladder disorder such as overactive bladder, such as when one or more stimulation elements  260  are configured to deliver energy to sacral nerve or other tissue. 
     In some embodiments, apparatus  10  is configured to treat fecal incontinence, overactive bladder (i.e. overactive bladder and/or urinary incontinence), and/or pelvic disorders, and implantable device  200 : comprises between 1 and 16 stimulation elements  260 , such as four or more electrodes; delivers electrical stimulation energy at a range of approximately between 10 Hz and 15 Hz (or a range of between 5 Hz and 25 Hz); delivers electrical stimulation energy with a pulse width of approximately between 180 μsec and 240 μsec (or between 1 μsec and 200 μsec); provides electrical stimulation energy with an amplitude of approximately 0.1V to 8.5V (e.g. providing a current between 0.1 mA to 10 mA, which can be adjusted in increments between 0.01 mA and 0.1 mA), such as an amplitude between 0.4V and 2.0V; delivers continuous electrical stimulation energy; delivers intermittent electrical stimulation energy, such as with a period between 8 seconds and 24 seconds and/or an on time between 8 seconds and 16 seconds; or an on time of several hours followed by an off time of several hours (such as 8 hours of stimulation ON and 16 hours of stimulation OFF or 16 hours on and 8 hours off, and 12 hour on and 12 hours off); delivers monopolar electrical energy; delivers bipolar electrical energy; and combinations of one or more of these. 
     In some embodiments, apparatus  10  is configured to treat an occipital neuralgia, such as migraine headache, headache and/or cluster headache, and one or more stimulation elements  260  (e.g. small column paddle electrodes, standard paddle electrodes or other electrodes) are positioned to stimulate nerve tissue selected from the group consisting of: occipital; supraorbital; infraorbital; greater occipital nerve (GON); lesser occipital nerve (LON); both supraorbital and GON; supratroclear; sphenopalantine (SPG); and combinations of one or more of these. 
     In some embodiments, apparatus  10  is configured to treat neuralgia, such as a neuralgia resulting from surgery (e.g. groin, shoulder, lung and/or amputation), trauma and/or phantom pain, and one or more stimulation elements  260  are positioned to stimulate nerve tissue. 
     In some embodiments, apparatus  10  is configured to treat neuralgia, such as a neuralgia resulting from groin surgery (e.g. hernia or other groin surgery), and one or more stimulation elements  260  are positioned to stimulate nerve tissue selected from the group consisting of: ilioinguinal; genitofemoral; iliohypogastric; and combinations of one or more of these. 
     In some embodiments, apparatus  10  is configured to treat neuralgia, such as a neuralgia resulting from shoulder surgery, and one or more stimulation elements  260  are positioned to stimulate axial nerve tissue (e.g. one or more stimulation elements  260  positioned on a lead  265  implanted in a suprascapular location). 
     In some embodiments, apparatus  10  is configured to treat neuralgia, such as a neuralgia resulting from lung surgery, and one or more stimulation elements  260  are positioned to stimulate intercostal nerve tissue. 
     In some embodiments, apparatus  10  is configured to treat neuralgia, such as a neuralgia associated with carpal tunnel syndrome, and one or more stimulation elements  260  are positioned to stimulate median nerve tissue. 
     In some embodiments, apparatus  10  is configured to treat neuralgia, such as a neuralgia associated with temporomandibular joint disorder (TMJ), and one or more stimulation elements  260  are positioned to stimulate V2 of trigeminal nerve tissue. 
     In some embodiments, apparatus  10  is configured to treat neuralgia, such as a facial neuralgia, and one or more stimulation elements  260  are positioned to stimulate trigeminal nerve tissue. 
     In some embodiments, apparatus  10  is configured to treat neuralgia, such as a leg (sciatic) neuralgia, and one or more stimulation elements  260  are positioned to stimulate nerve tissue proximal a contributing lesion. 
     In some embodiments, apparatus  10  is configured to treat pelvic pain, such as interstitial cystitis and/or bladder pain, and one or more stimulation elements  260  are positioned to stimulate peripheral nervous system tissue (e.g. pudendal tissue and/or S-2, S-3 and/or S-4 roots) and/or central nervous system tissue (e.g. lower spinal cord and/or S3 neural foramen). 
     In some embodiments, apparatus  10  is configured to treat pelvic pain, such as anal pain, and one or more stimulation elements  260  are positioned to stimulate peripheral nerve tissue such as pudendal tissue and/or S-2, S-3 and/or S-4 roots. 
     In some embodiments, apparatus  10  is configured to treat subcutaneous pain, and one or more stimulation elements  260  (e.g. paddle electrodes) are positioned to stimulate nerve tissue. 
     In some embodiments, apparatus  10  is configured to treat diabetic neuropathy, such as painful diabetic neuropathy, and one or more stimulation elements  260  are positioned proximate the lower spinal cord (e.g. to stimulate S3 nerves) or other body location to stimulate nerve tissue. 
     In some embodiments, apparatus  10  is configured to treat visceral pain, angina and/or other pain, and one or more stimulation elements  260  are positioned to stimulate the vagus nerve. 
     In some embodiments, apparatus  10  is configured to treat peripheral vascular disease, diabetic neuropathy and/or other conditions associated with diabetes, such as to treat a disease or disorder selected from the group consisting of: peripheral diabetic neuropathic pain; painful diabetic peripheral neuropathy; peripheral vascular disease; peripheral arterial disease; peripheral artery disease; cardiac autonomic neuropathy; diabetic autonomic neuropathy; diabetic sensory neuropathy; diabetic motor neuropathy; diabetic sensorimotor neuropathy; diabetic muscular atrophy; diabetic neurovascular disease; and combinations of one or more of these. In these embodiments, lead  265  can be positioned proximate a nerve in the foot, leg, arm and/or sacrum (e.g. such that one or more stimulation elements  260  are positioned proximate the nerve to be stimulated). In some embodiments, lead  265  is positioned to stimulate the dorsal root ganglia to treat diabetic neuropathy (e.g. diabetic neuropathy of the hand and/or foot). Lead  265  can be implanted percutaneously and/or surgically as described herein. Lead  265  and/or one or more stimulation elements  260  can comprise a paddle electrode, such as one or more paddle electrodes implanted in the foot, leg and/or arm. Lead  265  and/or one or more stimulation elements  260  can comprise a cuff or hemi-cuff electrode surgically implanted around a nerve in the foot, leg and/or arm. Apparatus  10  can be configured to provide spinal cord stimulation, either through percutaneous insertion of one or more leads  265  in the epidural space or surgical implantation of a lead  265  comprising a paddle lead positioned in the epidural space. Apparatus  10  can be configured to provide transvascular stimulation of nerves in the foot, leg and/or arm, (e.g. to treat diabetic neuropathy) such as when one or more leads  265  are interventionally advanced into the venous or arterial system. Leads  265  can be positioned using percutaneous transforaminal placement in the sacral foramina, such as for treatment of foot or leg disorders. Leads  265  can be constructed and arranged for cephalocaudal insertion (retrograde) into the epidural space or sacral canal, such as for treatment of foot or leg disorders. Leads  265  can be constructed and arranged to provide dorsal root ganglion stimulation, such as for treatment of trunk, neck, head, back, foot, leg, arm and/or hand disorders. 
     One or more leads  265  (e.g. each including one or more stimulation elements  260 ) can be constructed and arranged to stimulate tibial nerve fibers, such as to treat diabetic neuropathy and/or diabetic related maladies of the foot. The tibial nerve can be accessed as described herein. 
     One or more leads  265  can be configured to stimulate the peroneal nerve or saphenous nerve, such as at one or more locations described herebelow. The peroneal nerve can be accessed percutaneously or surgically behind the knee in the popliteal fossa where it branches off of the sciatic nerve. It can also be accessed as it wraps around the lateral aspect of the knee just prior to diving under the fibularis longus and extensor digitorum longus muscles. The deep fibular nerve (a branch of the peroneal nerve) innervates top medial foot, whereas the superficial fibular (peroneal) innervates top of both medial and lateral foot. In some embodiments, stimulation element  260  comprises one or more electrodes positioned in the anterior tibial vein and/or artery to transvascularly stimulate the deep fibular nerve. The saphenous nerve comes off the femoral nerve deep in the thigh. It passes around the medial aspect of the knee medial to the patella. It then runs down the medial shin adjacent to the tibia, gastrocnemius and soleus muscles where it can be accessed surgically or percutaneously. It then surfaces just as it warps around the anterior aspect of the medial malleolus where it supplies the medial posterior foot in front of heel. The medial sural cutaneous nerve comes off of the tibial at the popliteal fossa, then runs down the back of the calf (over the gastrocnemius) and wraps around the posterior aspect of the lateral malleolus before innervating the lateral aspect of the sole and heel. In some embodiments, the saphenous nerve is transvascularly stimulated by positioning one or more stimulation elements  260  in a blood vessel selected from the group consisting of: femoral vein; femoral artery; great saphenous vein; great saphenous artery; and combinations of one or more of these. In some embodiments, the sural nerve is stimulated. In these embodiments, the sural nerve can be transvascularly stimulated by positioning one or more stimulation elements  260  in the saphenous vein. 
     One or more leads  265  can be configured to stimulate the median nerve, ulnar nerve and/or radial nerve. The median nerve can be accessed percutaneously in the upper arm lateral to the brachial vein and/or artery, but medial to the biceps muscle, whereas the ulnar nerve runs medial to the brachial artery in the upper arm. The median nerve passes through the anterior aspect of the elbow under the bicipital aponeurosis. The ulnar nerve runs medial and posterior to the medial epicondyle of the humerus. The median nerve can also be accessed in the wrist just proximal to the palm and the palmar carpal ligament. The ulnar nerve can be accessed just proximal to the palmar carpal ligament adjacent to the pisiform. The radial nerve can be accessed percutaneously just as it passes anterior to the lateral epicondyle. In some embodiments, apparatus  10  can be configured to transvascularly stimulate at least one of a median nerve, an ulnar nerve or a radial nerve, and stimulation element  260  can comprise one or more electrodes positioned in a vessel selected from the group consisting of: brachial vein; brachial artery; basilic vein; basilic artery; deep vein of the arm; deep artery of the arm; and combinations of one or more of these. In some embodiments, apparatus  10  can be configured to transvascularly stimulate at least one of a median nerve or an ulnar nerve, and stimulation element  260  can comprise one or more electrodes positioned in a vessel selected from the group consisting of: brachial vein; brachial artery; and combinations of one or more of these. In some embodiments, apparatus  10  can be configured to transvascularly stimulate the radial nerve, and stimulation element  260  can comprise one or more electrodes positioned in a vessel selected from the group consisting of: deep vein of arm; deep artery of arm; basilic vein; radial collateral vein; radial collateral artery; medial collateral vein; medial collateral artery; radial vein; radial artery; and combinations of one or more of these. In some embodiments, apparatus  10  can be configured to transvascularly stimulate the medial cutaneous nerve, and stimulation element  260  can comprise one or more electrodes positioned in the basilic vein. In some embodiments, apparatus  10  is configured to transvascularly stimulate the ulnar nerve, and stimulation element  260  can comprise one or more electrodes positioned in a vessel selected from the group consisting of: ulnar collateral vein; ulnar collateral artery; ulnar vein; ulnar artery; and combinations of one or more of these. In some embodiments, apparatus  10  is configured to transvascularly stimulate the median nerve, and stimulation element  260  can comprise one or more electrodes positioned in a vessel selected from the group consisting of: brachial vein; brachial artery; ulnar vein; ulnar artery; and combinations of one or more of these. 
     As described herein, one or more leads  265  can be positioned to stimulate the spinal cord, such as via percutaneous insertion of a lead  265  in the epidural space or surgical implantation of the lead  265  (e.g. a paddle lead) in the epidural space. A lead  265  can be placed such that one or more stimulation elements  260  (e.g. one or more electrodes) are positioned from T5-S5, such as to capture the area of pain or reduced circulation of the leg or foot. One or more stimulation elements  260  of one or more leads  265  can be positioned from C2 to T8, such as to capture the area of pain or reduced circulation of the arm or hand. One or more leads  265  can be placed along the midline, unilaterally and/or bilaterally over the dorsal columns, in the gutter (over dorsal roots) and/or in the dorsal root entry zone. Leads  265  can span several vertebral levels or they can be positioned to span a single level. 
     One or more stimulation elements  260  (e.g. one or more electrodes attached to one or more leads  265 ) can be positioned to transvascularly stimulate one or more nerves, such as one or more nerves in the foot, leg and/or arm, such as when the one or more stimulation elements  260  are implanted within one or more blood vessels of the venous and/or arterial system. 
     In the leg, the tibial nerve, sacral roots and/or deep fibular nerve can be stimulated, such as when a lead  265  accesses the tissue to be stimulated through a transvascular approach, such as via the femoral vein and/or artery, as described herein. The deep fibular nerve can be stimulated by one or more stimulation elements  260  positioned in the anterior tibial vein and/or the anterior tibial artery. In the arm, the median nerve, ulnar nerve, superior ulnar nerve, medial cutaneous nerve and/or radial nerve can be stimulated, such as when lead  265  accesses the tissue to be stimulated through a transvascular approach, such as via the brachial vein and/or artery, the basilic vein and/or artery, and/or the deep vein and/or artery. 
     One or more stimulation elements  260  (e.g. one or more electrodes attached to one or more leads  265 ) can be positioned to stimulate dorsal root ganglia that supply the following nerves (e.g. to treat the leg and/or foot): common peroneal (L4-S2); tibial (L4-S3); femoral (L2-L4); and combinations of one or more of these. One or more stimulation elements  260  (e.g. one or more electrodes attached to one or more leads  265 ) can be positioned to stimulate dorsal root ganglia that supply the following nerves (e.g. to treat the hand and/or arm): radial (C5-T1); median (C5-T1); ulnar (C7-T1); and combinations of one or more of these. In these embodiments, one or more leads  265  can be passed through the intervertebral foramina, either unilaterally or bilaterally, at a single vertebral level or at multiple vertebral levels. 
     In some embodiments, apparatus  10  is configured to treat post-amputation pain, such as to treat a disease or disorder selected from the group consisting of: phantom limb pain; phantom stump pain; acute and persistent stump pain; limb pain; neuroma; Morton&#39;s neuroma; neurilemoma; neurolemoma; Schwann cell tumor; phantom limb itch; phantom limb sensations; and combinations of one or more of these. Apparatus  10  can be configured to treat the conditions associated with post-amputation pain (i.e. stump pain), such as by using a high frequency alternating current (HFAC) block approach. In these embodiments, one or more leads  265  can be implanted such that one or more stimulation elements  260  stimulate one or more nerves in the leg, arm and/or sacrum. One or more leads  265  can be surgically implanted, such as when lead  265  comprises a paddle electrode positioned near a nerve in the foot, leg or arm and/or a cuff electrode or hemi-cuff electrode positioned to at least partially surround a nerve in the foot, leg or arm. One or more leads  265  can be positioned to stimulate the spinal cord, such as via a percutaneous insertion of the leads  265  in the epidural space or surgical implantation of the lead  265  (e.g. a paddle lead) in the epidural space. One or more leads  265  can be positioned to provide transvascular stimulation of nerves in the leg or arm, such as when one or more stimulation elements  260  are implanted within a vein or artery. One or more leads  265  can be implanted using percutaneous transforaminal placement in the sacral foramina, such as for treatment of leg stump pain. One or more leads  265  can be implanted using cephalocaudal insertion (retrograde) into the epidural space or sacral canal, such as for treatment of leg stump pain. One or more leads  265  can be positioned to perform dorsal root ganglion stimulation and/or block, such as for treatment of leg and/or arm stump pain. 
     In some embodiments, apparatus  10  is configured to treat occipital and/or headache (HA) pain, such as when apparatus  10  is configured to treat a disease or disorder selected from the group consisting of: occipital neuralgia; cervicogenic headache; tension headache; chronic and episodic migraine headache; hemicrania continua; trigeminal autonomic cephalalgias (TACs); chronic and episodic cluster headache; chronic and episodic paroxysmal hemicranias; short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT); short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms (SUNA); long-lasting autonomic symptoms with hemicrania (LASH); post-traumatic headache; and combinations of one or more of these. 
     Apparatus  10  can be configured to treat the conditions associated with headache pain and/or occipital neuralgia by stimulating one or more nerves in the head, such as one or more nerves selected from the group consisting of: greater and/or lesser occipital nerve (e.g. which arise from C2 and C3); the greater and/or lesser auricular nerves (e.g. which also arise from C2/C3); the third (least) occipital nerve (e.g. which arises from C3); and combinations of one or more of these. The infraorbital or supraorbital nerves can be access subcutaneously below and above the eye, respectively. Apparatus  10  can be configured to stimulate auriculotemporal, supratrochlear and/or sub-occipital nerves. To stimulate any of these nerves, lead  265  (e.g. a cylindrical SCS-type lead) can be inserted percutaneously either subcutaneously or under the muscle. Alternatively, surgical (e.g. direct cut-down) can be performed to insert lead  265  (e.g. a cylindrical lead, a paddle lead, a cuff or hemi-cuff electrode) proximate, one and/or around these nerves. Alternatively or additionally, the nerves can be accessed transvascularly as described herein (e.g. when one or more stimulation elements  260  are implanted in a blood vessel). Housing  210 / 810  can be implanted anywhere in the head under the skin, including: behind the ear, back of the head, the neck, in the face, and the like, where an one or more external devices  500  can be positioned in, on and/or within a hat, headband, glasses, goggles, earpiece, necklace, patch, and the like. Apparatus  10  can be configured to treat headache pain and/or occipital neuralgia by stimulating tissue in the cervical spinal cord (C2-C3), for example proximate the location the nerve enters the cord from the foramen. One or more leads  265  can be placed over the dorsal columns, in the gutter, over the dorsal root entry zone and/or out in the foramen at the dorsal root ganglion. In some embodiments, the trigeminal and pterygopalatine ganglia are accessed by inserting one or more leads  265  through the face or the roof of the mouth. In these embodiments, housing  210 / 810  can be placed anywhere in the head under the skin, as described herein. 
     In some embodiments, apparatus  10  is configured to treat post-herpetic neuralgia, such as to treat a disease or disorder selected from the group consisting of: shingles; herpes zoster; zoster; zona; varicella zoster virus infection; zoster sine herpete; fever blisters; herpes zoster blisters; herpes zoster rash; and combinations of one or more of these. In some embodiments, apparatus  10  is configured to treat post-herpetic neuralgia using high frequency alternating current (HFAC) block approach. In these embodiments, one or more leads  265  can be implanted such that one or more stimulation elements  260  stimulate one or more nerves in the leg, arm, torso and/or sacrum. One or more leads  265  can be surgically implanted, such as when lead  265  comprises a paddle electrode positioned near a nerve in the foot, leg, torso and/or arm and/or a cuff electrode or hemi-cuff electrode positioned to at least partially surround a nerve in the foot, leg, torso or arm. One or more leads  265  can be positioned to stimulate the spinal cord, such as via a percutaneous insertion of the leads  265  in the epidural space or surgical implantation of the lead  265  (e.g. a paddle lead) in the epidural space. One or more leads  265  can be positioned to provide transvascular stimulation of nerves in the leg, torso and/or arm, such as when one or more stimulation elements  260  are implanted within a vein or artery. One or more leads  265  can be implanted using percutaneous transforaminal placement in the sacral foramina, such as for treatment of leg or foot pain. One or more leads  265  can be implanted using cephalocaudal insertion (retrograde) into the epidural space or sacral canal, such as for treatment of leg or foot pain. One or more leads  265  can be positioned to perform dorsal root ganglion stimulation and/or block, such as for treatment of leg, torso and/or arm pain. 
     In some embodiments, apparatus  10  is configured to treat angina, such as to treat a disease or disorder selected from the group consisting of: angina; chest pain caused by reduced blood flow to the heart muscle; chest pain associated with coronary artery disease such as squeezing, pressure, heaviness, tightness or pain in the chest; recurring angina pectoris; acute angina pectoris; chronic angina pectoris; acute coronary syndrome; chest pain; coronary artery spasms; microvascular angina; Prinzmetal&#39;s angina; angina inversa; stable or common angina; unstable angina; variant angina; and combinations of one or more of these. 
     In some embodiments, apparatus  10  is configured to treat carpal tunnel syndrome, such as to treat a disease or disorder selected from the group consisting of median nerve entrapment; tingling and/or numbness in fingers or hand; median nerve irritation or compression; narrowing of the carpal tunnel; and combinations of one or more of these. In these embodiments, apparatus  10  can be configured to deliver stimulation to median nerve tissue; ulnar nerve tissue and/or radial nerve tissue. 
     In some embodiments, apparatus  10  is configured to treat erectile dysfunction (ED), such as to treat a disease or disorder selected from the group consisting of impotence; male sexual dysfunction; inability to develop or maintain an erect penis; cardiogenic ED; vasculogenic ED; diabetic ED; neurogenic ED; traumatic ED; post-prostatectomy ED; hormonal ED; hyopogonadism; pharmacological ED; and combinations of one or more of these. 
     In some embodiments, apparatus  10  is configured to treat complex regional pain syndrome (CRPS), such as to treat a disease or disorder selected from the group consisting of CRPS type 1; CRPS type 2; reflex sympathetic dystrophy; causalgia; reflex neurovascular dystrophy; amplified musculoskeletal pain syndrome; systemic autonomic dysregulation; neurogenic edema; musculoskeletal pain; and combinations of one or more of these. 
     In some embodiments, apparatus  10  is configured to treat knee pain. Knee pain from joint degeneration or join replacement surgery can be treated via stimulation of the nerves innervating the knee and/or via stimulation of the tissue surrounding the knee (sometimes referred to as peripheral field stimulation). Apparatus  10  can comprise between one and eight leads  265  whose stimulation elements  260  are placed near and around the knee. In some embodiments, four leads  265  are placed, in locations medial, lateral, superior and inferior to the knee. The leads  265  can be placed subcutaneously for field stimulation, or they can be placed directly adjacent to specific nerve targets. Applicable nerve targets are as follows: medial knee can include medial femoral cutaneous and infrapatellar cutaneous branches of saphenous nerve; lateral knee can include constant articular branches of common peroneal, lateral retinacular nerve; anterior knee can include lateral, medial, and anterior cutaneous femoral nerve, infrapatellar branch of saphenous nerve, medial and lateral retinacular nerve and articular branches of peroneal nerve; posterior knee can include obturator, posterior tibial and sciatic nerves. In addition, the following nerves can be stimulated via stimulation elements  260  to treat knee pain: nerves arising from the tibial nerve such as the superior, middle and inferior genicular nerves; nerves arising from the common peroneal such as the superior lateral, inferior lateral, and recurrent genicular nerves; and nerves arising from the obturator nerve such as the genicular branch of obturator; and nerves arising from the femoral nerve such as the saphenous nerve. Each of these targets can be stimulated transvascularly by one or more stimulation elements  260 . 
     In some embodiments, one or more implantable devices  200 / 800  are configured to deliver stimulation energy (e.g. via one or more stimulation elements  260  comprising an electrode) with a stimulation waveform comprising one or more high frequency signals (e.g. a signal comprising one or more high frequency components). For example, one or more implantable devices  200 / 800  can deliver one or more stimulation waveforms comprising one or more signals above 600 Hz, such as one or more signals above 1.0 kHz, 1.2 kHz, 5 kHz, 10 kHz or 25 kHz. In these embodiments, the delivered stimulation waveform can be configured to be void of (i.e. not include) one or more lower frequency signals, such as by not including any signals at a frequency below 100 Hz, below 500 Hz, below 1000 Hz, below 1200 Hz or below 1500 Hz. 
     One or more implantable devices  200 / 800  can be configured to deliver stimulation energy with a stimulation waveform that varies over time. In some embodiments, one or more stimulation parameters of the stimulation waveform are randomly varied over time, such as by using a probability distribution as described in applicant&#39;s co-pending application International PCT Patent Application Serial Number PCT/US2017/017978, titled “Apparatus with Enhanced Stimulation Waveforms”, filed Feb. 15, 2017. Each stimulation waveform can comprise one or more pulses, such as a group of pulses that are repeated at regular and/or irregular intervals. In some embodiments, a pulse can comprise delivery of electrical energy, such as electrical energy delivered in one or more phases (e.g. a pulse comprising at least a cathodic portion and an anodic portion). In some embodiments, single or groups of pulses are provided at time-varying modes of repetition (e.g. regular intervals for a period, then a period of irregular intervals) or at regular intervals with occasional (random) spurious pulses inserted (creating a single irregular event in an otherwise regular series). Non-limiting examples of waveform variations include: a variation in frequency (e.g. frequency of one or more signals of the waveform); variation of a signal amplitude; variation of interval time period (e.g. at time period between pulses or a time period between pulse trains); variation of a pulse width; multiple piecewise or continuous variations of one of more stimulation parameters in a single pulse (e.g. multi-step, multi-amplitude in one “super-pulse”); variation of pulse symmetry (e.g. via active drive, passive recovery and/or active-assisted passive recovery); variation of stimulation energy over a time window and/or overlapping time windows; variation of the power in the frequency spectrum of the stimulation waveform; and combinations of one or more of these. In some embodiments, apparatus  10  and/or implantable device  200 / 800  can be configured to vary a stimulation waveform “systematically” such as a variation performed temporally (e.g. on predetermined similar or dissimilar time intervals) and/or a variation performed based on a parameter, such as a measured parameter that can be based on a signal produced by a sensor of implantable device  200 / 800  or another component of apparatus  10  (e.g. one or more of functional element  299 / 599 / 899 ). Alternatively or additionally, apparatus  10  and/or implantable device  200 / 800  can be configured to vary a stimulation waveform randomly. Random variation shall include discrete or continuous variations that can be selected from a distribution, such as a probability distribution selected from the group consisting of a uniform distribution; an arbitrary distribution; a gamma distribution; a normal distribution; a log-normal distribution; a Pareto distribution; a Gaussian distribution; a Poisson distribution; a Rayleigh distribution; a triangular distribution; a statistic distribution; and combinations of one or more of these. Random pulses or groups of pulses can be generated based on randomly varying one or more stimulation signal parameters as described herein. One or more stimulation parameters can be varied randomly through the use of one or more probability distributions, as described herebelow. 
     In some embodiments, the amplitude of a signal delivered by one or more implantable devices  200 / 800  is adjusted to prevent discomfort to the patient (e.g. paresthesia or other undesired condition) from the stimulation signal. In some embodiments, the amplitude of the stimulation signal can be ramped (e.g. up and/or down), a single time or multiple times (e.g. continuously or intermittently). In some embodiments, a titration procedure can be performed (e.g. the trial period of the present inventive concepts) to “set” one or more stimulation parameters based on avoiding patient discomfort. 
     In some embodiments, one or more implantable devices  200 / 800  are configured to deliver stimulation energy (e.g. via one or more stimulation elements  260  comprising an electrode) with a stimulation waveform comprising one or more waveforms configured to one or more specific conditions of a patient. Each stimulation waveform can comprise a series of continuous pulses, intermittent pulses, and/or spurious pulses (e.g. occasional events in an otherwise continuous stream). Each pulse can comprise a pulse train that is repeatedly delivered by implantable device  200 / 800 , the train comprising one or more cathodic pulses and/or one or more anodic pulses. In some embodiments, implantable device  200 / 800  delivers a multiphasic pulse comprising at least two cathodic pulses and/or anodic pulses, with or without any time between each pulse. For example, implantable device  200 / 800  can deliver a biphasic pulse comprising a cathodic pulse followed by an anodic pulse, a triphasic pulse comprising a cathodic pulse followed by an anodic pulse followed by a second cathodic pulse, or any series of two or more cathodic and/or anodic pulses. In some embodiments, delivered pulses are exponential in nature (e.g. comprise an exponential portion), such as dynamic return pulses that exceed a minimum current (e.g. at least 1 mA, 10 mA or 50 mA) for a short duration (e.g. for approximately 1 μsec), and then decay to lower current levels (e.g. a level of approximately 100 nA), with a time constant on the order of 1 μsec to 100 μsec. 
     The stimulation waveforms delivered by implantable device  200 / 800  can comprise one or more high frequencies (e.g. as described herein). The stimulation waveform frequency or other stimulation parameter can be set and/or adjusted (hereinafter “adjusted”) to optimize therapeutic benefit to the patient and minimize undesired effects (e.g. paresthesia or other patient discomfort). In some embodiments, a stimulation waveform is adjusted based on a signal produced by a sensor of apparatus  10  (e.g. a sensor of implantable device  200 / 800 , such as a stimulation element  260  or functional element  299 / 899  configured as a sensor). Adjustment of a stimulation waveform parameter can be performed automatically by the implantable device  200 / 800  and/or via an external device  500  and/or programmer  550 . 
     In some embodiments, a pulse shape of a stimulation waveform can be varied, such as a pulse shape comprising: a sinusoidal geometry; a square geometry (e.g. a waveform comprising a square wave); a rectangular geometry; a triangular geometry; (e.g. symmetric or asymmetric); a trapezoidal geometry; a sawtooth geometry; a ramped geometry; an exponential geometry; a piece-wise step function geometry; a root-raised cosine geometry; and combinations of one or more of these. 
     In some embodiments, a charge recovery phase (e.g. anodal phase) of a stimulation waveform is varied by implantable device  200 / 800 . 
     Inter-pulse gap, the time between one or more pulses (e.g. a biphasic or other multiphasic pulse that is repeated continuously), can be varied systematically and/or randomly by implantable device  200 / 800 . In some embodiments, inter-pulse gap between one or more pulses comprises zero time (i.e. a first pulse is immediately followed by a similar or dissimilar second pulse). In some embodiments, inter-pulse gap is varied systematically, such as on a routine basis (i.e. temporally) and/or varied based on a signal produced by a sensor of apparatus  10 . Alternatively or additionally, inter-pulse gap can be varied randomly, such as a random variation based on a distribution (e.g. a probability distribution with a pre-determined shape) as described herebelow. 
     In some embodiments, implantable device  200 / 800  delivers a stimulation waveform comprising a series of frequency modulated (FM) pulses, such that the frequency of stimulation varies. Implantable device  200 / 800  can be configured to deliver a frequency modulated stimulation waveform comprising a carrier signal, at a carrier frequency, that is modulated continuously between a first frequency and a second frequency. For example, implantable device  200 / 800  can deliver a stimulation waveform that modulates between 2.0 kHz and 3.0 kHz every second (e.g. comprising a carrier signal at 2.5 kHz that is modulated at 1 Hz) with a modulation range (the excursion from the carrier signal) of +/−500 Hz. In some embodiments, implantable device  200 / 800  can deliver a stimulation waveform that comprises: a carrier frequency between 1 kHz and 50 kHz, a modulation frequency between 0.1 Hz and 10 kHz and/or a modulation range between 1 Hz and the carrier frequency. 
     In some embodiments, implantable device  200 / 800  delivers a stimulation waveform comprising a series of amplitude modulated (AM) pulses, such that the amplitude of stimulation varies (e.g. varying the amplitude of the voltage and/or current of the stimulation signal). The amplitude of delivered current can be varied in a single amplitude modulated sweep, such as a sweep from 2 mA to 3 mA. In some embodiments, amplitude of a signal can be varied continuously, such as when current is varied between 2 mA and 3 mA every second (e.g. a signal comprising a modulation frequency of 1 Hz). In these embodiments, the depth of modulation would be 33%, where depth of modulation is equal to 1-[lower range/upper range]. In some embodiments, amplitude of delivered current fluctuates between 1 mA and 3 mA (i.e. a depth of modulation of 66%), while in other embodiments, current fluctuates between 0 mA and 3 mA (e.g. a depth of modulation of 100%). In some embodiments, implantable device  200 / 800  is configured to deliver an amplitude modulated signal comprising: a carrier frequency between 1 Khz and 50 kHz; a modulation frequency between 0.1 Hz and the carrier frequency and/or a depth of modulation between 0.1% and 100%. 
     In some embodiments, implantable device  200 / 800  delivers a stimulation waveform comprising delivery of continuously balanced analog current waveforms, for example from a differential Howland current source. In these embodiments, there are not independent pulses, but rather there is true analog frequency and amplitude modulation. Periods of delivering stimulation (or presence of balanced differential analog stimulation) and periods of no stimulation (e.g. a quiescent period) can be included. In some embodiments, controller  250 / 850  comprises one or more reconfigurable stimulation blocks including one or more Howland or other current sources. The one or more current sources (e.g. two or more current sources) can each be attached to a stimulation element  260  (e.g. in a monopolar configuration when the current source is also connected to housing  210 / 810  or in a bipolar configuration when the current source is connected to a pair of stimulation elements  260 ). Alternatively, controller  250 / 850  can comprise one or more current sources that are attached to a matrix of switches that selectively connect the one or more current sources to multiple stimulation elements  260  (e.g. connect a single current source to 2, 4, 8, 12 or 16 electrodes). In some embodiments, controller  250 / 850  is configured such that a stimulation waveform signal provided to the current source passes through a capacitor (e.g. capacitor C1 shown), the capacitor providing DC balance. 
     In some embodiments, implantable device  200 / 800  delivers a stimulation waveform comprising delivery of multiple trains of pulses that are delivered intermittently, a “burst stimulation” waveform as defined hereabove. For example, implantable device  200 / 800  can be configured to deliver a series or train of five pulses, each with a 1 msec pulse width, and each of the five pulses can be separated by an inter-pulse gap of 4 msec, creating a train-on period of 16 msec. These five pulses can be repeated every 25 msec (the “inter-train period”). In some embodiments, implantable device  200 / 800  can be configured to deliver a burst stimulation waveform comprising a pulse width between 5 μsec and 1 msec. Implantable device  200 / 800  can deliver a train or burst stimulation waveform comprising pulses with constant pulse widths and/or varying pulse widths, such as when the pulse widths (and/or other stimulation parameters) are varied randomly and/or systematically. Implantable device  200 / 800  can deliver a train or burst stimulation waveform with a varied or constant pulse shape selected from the group consisting of: sinusoid; square, rectangle; triangle (symmetric or asymmetric); trapezoid; sawtooth; ramp (e.g. a linear ramp); exponential curve; piece-wise step function; and combinations of one or more of these. Implantable device  200 / 800  can deliver a train or burst stimulation waveform with an inter-pulse gap less than inter-train period. The inter-pulse gap can be relatively constant or it can be varied, such as when implantable device  200 / 800  randomly varies the inter-pulse gap or varies the inter-pulse gap systematically. In some embodiments, the inter-pulse gap between any two pulses within a pulse train (or burst) can be varied between 0.1 μsec and the inter-train period (or inter-burst period). Implantable device  200 / 800  can deliver a train stimulation waveform with an inter-pulse gap between 1 μsec and 1 second. Implantable device  200 / 800  can deliver a burst stimulation waveform with an inter-train period between 1 μsec and 1 second. Implantable device  200 / 800  can deliver a burst stimulation waveform with an inter-burst period between 20 μsec and 24 hours. The inter-burst period can be relatively constant or it can be varied, such as when implantable device  200 / 800  randomly varies the inter-burst period or varies the inter-burst period systematically. In some embodiments, inter-burst period is varied by the user, such as via a user using programmer  550 . In these embodiments, user activation can be regulated with one or more safeguards or other limits such as those incorporated into patient controlled analgesia devices. The inter-train period can be varied between 1 μsec and 24 hours. Implantable device  200 / 800  can deliver a train or burst stimulation waveform with a train-on period (the time between the onset of a first pulse in a pulse train to the end of the last pulse in a pulse train) between 10 μsec and 24 hours. The train-on and/or burst-on period can be relatively constant or it can be varied, such as when implantable device  200 / 800  randomly varies the train-on and/or burst-on period or varies the train-on and/or burst-on period systematically. Implantable device  200 / 800  can deliver a train or burst stimulation waveform with a train or burst envelope selected from the group consisting of: cosine; cosine-squared; sine; square; rectangle; triangle (symmetric or asymmetric); trapezoid: sawtooth; ramp (e.g. linear ramp); and combinations of one or more of these. Implantable device  200 / 800  can deliver a train and/or burst stimulation waveform with a train ramp duration or burst ramp duration between 1 μsec to 10 minutes. Implantable device  200 / 800  can deliver a train and/or burst stimulation waveform with a depth of modulation between train and/or bursts of between 10% and 99%. For example, between some or all of the trains and/or bursts (burst-off or train-off periods), a signal may be present and may contain the same or different elements contained in the train-on and/or burst-on period. These burst-off or train-off periods may comprise a quiescent period as described herein. The amplitude of the signal contained in these quiescent period may be from 0% to 99% of the signal amplitude during the train-on and/or burst-on period, such as a signal with an amplitude less than 50% of the signal amplitude during the train-on and/or burst-on period or another amplitude below a neuronal excitation threshold. 
     In some embodiments, apparatus  10  is configured to deliver stimulation energy to dorsal root ganglion and/or spinal cord tissue to treat a condition such as pain. In these and other embodiments, apparatus  10  can be configured to provide a stimulation waveform comprising: a combination of low frequency stimulation (e.g. electrical energy comprising a low frequency signal) and burst stimulation; burst stimulation (e.g. burst stimulation alone); a combination of low frequency stimulation and high frequency stimulation; a combination of low frequency stimulation, high frequency stimulation and burst stimulation; and combinations of one or more of these. The stimulation energy provided by apparatus  10  can be delivered to tissue via one or more stimulation elements  260 , such as two or more electrodes which deliver similar or dissimilar stimulation waveforms simultaneously and/or sequentially. Each of the stimulation waveforms can comprise one or more pulses comprising an entire phase or at least a portion of a phase at a superthreshold level. Alternatively or additionally, each of the stimulation waveforms can comprise one or more pulses comprising an entire phase or at least a portion of a phase at a subthreshold level. 
     In some embodiments, apparatus  10  is configured to vary one or more stimulation parameters to optimize (e.g. balance the benefits of): therapeutic benefit, system efficiency, stimulation efficiency, avoidance and/or reduction of paresthesia, and/or reduction of charge. 
     In some embodiments, implantable device  200 / 800  comprise a filament (e.g. a flexible filament comprising one or more wires, optical fibers, wave guides, and the like), conduit  298 / 898 , which extends from housing  210 / 810  as shown in  FIG. 1A . Port  290 / 890  is positioned on an end of conduit  298 / 898 . As described above, lead  265  can be operably attached to implantable device  200 / 800  via port  290 / 890  in one or more clinical procedures (e.g. a first clinical procedure in which lead  265  is attached to implantable device  200  at port  290  of conduit  298  and a subsequent second clinical procedure in which lead  265  is attached to implantable device  800  at port  890  of conduit  898 , such as is described herein in reference to  FIGS. 1  and/or  2 ). Lead  265  is shown prior to attachment to port  290 / 890  in  FIG. 1A . A tool, tool  61 , can be included to assist in the attachment of lead  265  to port  290 / 890 , such as tool  61  described herebelow. 
     In some embodiments, implantable device  200 / 800  comprises both conduit  298 / 898 , and a sleeve, collar or other attachment element, fitting  266 , which is used to create a seal, seal  267 , between lead  265  and port  290 / 890 . In  FIG. 1B , lead  265  has been connected to port  290 / 890 , and fitting  266  has been positioned about the connection, such as to create seal  267 . Seal  267  can be configured to prevent significant contamination from interfering with the operable connection (e.g. to prevent shorting of contacts, preventing loss or degradation of an electrical, optical and/or acoustic connection, and/or prevent another undesired effect). In some embodiments, implantable system  20  does not include fitting  266 , and a seal is provided between one or more portions of lead  265  and implantable device  200 / 800 . Fitting  266  and/or seal  267  can be configured to significant contamination for a limited period of time (e.g. seal  267  comprises a “temporary seal”), for example less than 1 week, less than one month, less than 2 months, and/or less than 3 months, such as when fitting  266  and/or seal  267  is present for a limited period of time (e.g. a limited period of time in which implantable device  200  and corresponding attachment port  290  are attached to lead  265  during a trial period as described herein). 
     Referring now to  FIG. 1C , a schematic view of two implantable devices is illustrated, the first implantable device comprising a pre-attached lead and the lead comprising a removable portion, consistent with the present inventive concepts. Implantable device  200  and implantable device  800  can be of similar construction and arrangement to those described hereabove in reference to  FIG. 1 . Lead  265  is shown attached to implantable device  200 , such as a permanent attachment made in a manufacturing process of implantable device  200 . In some embodiments, one or more gaskets, gasket  296  shown, is used to seal lead  265  to housing  210 . Lead  265  comprises one or more stimulation elements  260  (e.g. electrodes), which are operably connected to one or more internal components of implantable device  200  via conduit  263 . Implantable device  200  and attached lead  265  can be implanted in the patient, such as to perform a trialing procedure of the present inventive concepts. 
     Lead  265  can comprise a removable distal portion  264 , such that detachment of distal portion  264  from the remainder of lead  265  exposes contacts  262 ′. For example, after a trial procedure is performed with implantable device  200  and lead  265  (e.g. in the condition shown in  FIG. 1C ), distal portion  264  can be detached from the more proximal portion of lead  265  (and thus from implantable device  200 ), such that contacts  262 ′ can be advanced into connector  890  of implantable device  800  such that contacts  262 ′ operably connect to contacts  890 . In some embodiments, lead  265  comprises a sleeve, or other seal-creating element, surrounding the junction of distal portion  264  and the remaining (proximal) portion of lead  265 , not shown but such as sleeve  266  described hereabove in reference to  FIG. 1B . 
     Referring now to  FIG. 2 , a flow chart of a method of providing stimulation for an initial trial period, and a subsequent therapy period is illustrated, consistent with the present inventive concepts. The method  2000  of  FIG. 2  can be accomplished with apparatus  10  and any of its components as described in reference to the associated figures, and will be described using those components. STEPS  2100 ,  2200  and  2300  represent a first clinical procedure (e.g. a surgery such as a minimally invasive surgery) performed on a patient to receive stimulation via apparatus  10 . In STEP  2100 , lead  265  is implanted in the patient. In STEP  2200 , lead  265  is attached to one or more implantable stimulation devices, such as when lead  265  is attached to implantable device  200  at attachment port  290 . In STEP  2300 , implantable device  200  is implanted in the patient. STEPs  2100 ,  2200  and  2300 , can be performed in any order. 
     In STEP  2400 , a trial period is performed in which implantable device  200  delivers stimulation energy to the patient, such as to attempt to provide pain relief or other therapy as described herein. During the trial period of STEP  2400 , stimulation can be provided in order to evaluate use of apparatus  10  to provide therapy to the patient, such as is described hereabove in reference to  FIG. 1 . During the trial period, stimulation settings can be varied (e.g. variations of stimulation element  260  positions, configurations and/or combinations; stimulation frequencies; stimulation waveform shapes; and/or stimulation pulse widths and/or amplitudes), such as to optimize or at least improve therapeutic benefit to the patient. The trial period of STEP  2400  can have a duration of at least 1 week, at least 2 weeks, at least 1 month, at least 2 months, and/or at least 3 months. During the trialing period, implantable device  200  receives power and data from external system  50  (e.g. from one or more external devices  500 ), as is described herein, avoiding the need for a large capacity energy storage assembly  270  (e.g. reducing the volume of implantable device  200 ). 
     STEPS  2500 ,  2600  and  2700  represent a second clinical procedure (e.g. a surgery such as a minimally invasive surgery) performed on the patient. In STEP  2500 , lead  265  is disconnected from implantable device  200  (e.g. disconnected from attachment port  290 ), and implantable device  200  is explanted from the patient. In STEP  2600 , lead  265  is attached to one or more other implantable stimulation devices, such as when lead  265  is attached to implantable device  800  at attachment port  890 . In STEP  2700 , implantable device  800  is implanted in the patient. STEPs  2500 ,  2600  and  2700  can be performed in any order. 
     In STEP  2800 , a therapy period is performed in which implantable device  800  delivers stimulation energy to the patient, such as to provide pain relief or other therapy as described herein. Implantable device  800  can provide long-term therapy to the patient for a therapy period of at least 1 month, at least 6 months, at least 1 year and/or at least 2 years. During the therapy period, implantable device  800  may not receive any power from external system  50 , such as when energy storage assembly  870  comprises a capacity sufficient to deliver stimulation for the entire therapy period. In alternative embodiments, energy storage assembly  870  is recharged periodically (e.g. not continually), such as via a wireless recharge (e.g. via a RF or other wireless transmitter, magnetic coupling, inductive coupling, capacitive coupling and/or other wireless power transmission means). 
     In some embodiments, the therapy period of STEP  2800  is stopped due to one or more of: patient therapy is no longer needed; energy storage assembly  870  is depleted (e.g. after a period of at least 1 year); and/or an infection or other patient complication occurs. In these embodiments, all or a portion of the method of  FIG. 2  can be repeated, such as by returning to STEP  2100 ,  2200  or  2300 , or returning directly to STEP  2500 ,  2600  or  2700 . 
     In some embodiments, after completion of STEP  2400 , use of apparatus  10  is stopped, such as when adequate therapeutic results are not achieved in STEP  2400  (e.g. despite various changes in stimulation parameters). Alternatively, after completion of STEP  2400 , if adequate therapy is achieved, long-term therapy can continue to be provided by implantable device  200 , without the need for the second clinical procedure of STEPs  2500 ,  2600  and  2700  nor the use of a second implantable device such as implantable device  800 . 
     Referring now to  FIG. 3 , a perspective view of an apparatus comprising a temporary implantable device and an attachable lead for use in a trialing period is illustrated, consistent with the present inventive concepts. Apparatus  10  comprises implantable device  200 , lead  265 , and other components of similar construction and arrangement to those described hereabove in reference to  FIG. 1 . Implantable device  200  of  FIG. 3  comprises a clam-shell shaped housing, housing  210 ′. 
     During a clinical procedure, the proximal portion  268  of lead  265  is inserted into attachment port  290  comprising two hinged portions (e.g. two flexible-hinge portions) of housing  210 ′ in a clam-shell arrangement. Housing  210 ′ is compressed to make electrical, optical, acoustic, mechanical and/or other operable connection with proximal portion  296  of lead  265 , as well as sealingly surround proximal portion  268 , such that contacts  262  are maintained within housing  210 ′ and a seal (e.g. a temporary seal as described herein) is maintained to at least temporarily prevent contamination from interfering with the connection between contacts  262  and correspondingly aligned contacts  292  of attachment port  290 . Implantable device  200  can comprise one or more gaskets and/or other sealing material, gasket  296  shown, to assist in creating the seal between lead  265  and implantable device  200 . 
     In some embodiments, lead  265  is configured to be detached from implantable device  200  and subsequently operatively attached to implantable device  800  (e.g. in a second clinical procedure in which implantable device  800  is implanted). In some embodiments, lead  265  comprises a removable distal portion configured to subsequently attach to second implantable stimulator  800 , as described hereabove in reference to  FIG. 1C . 
     Referring now to  FIGS. 4A-B , top views of an apparatus comprising a temporary implantable device and an attachment lead for use in a trialing period is illustrated, consistent with the present inventive concepts. Implantable device  200  of  FIGS. 4A-B  is shown with the top portion of housing  210  removed for illustrative clarity. Apparatus  10  comprises implantable device  200 , lead  265 , and other components of similar construction and arrangement to those described hereabove in reference to  FIG. 1 . Implantable device  200  of  FIGS. 4  A-B comprises attachment port  290  which extends from the bottom to the top of implantable device  200 , such as to receive the proximal portion of lead  265  including all contacts  262 . 
     Apparatus  10  can include tool  61 , configured to slidingly engage and expand (e.g. radially expand) attachment port  290 , such that proximal portion  268  can be inserted into tool  61 , while tool  61  is in place within attachment port  290 , as shown in  FIG. 4A . Radial expansion of attachment port  290  can include expansion and/or displacement of one or more of: housing  210 ; and/or one or more gaskets within attachment port  290 , gasket  296 . Subsequently, tool  61  can be removed from attachment port  290 , such that attachment port  290  radially contracts, as shown in  FIG. 4B . After removal of tool  61 , seal  267  is created, such as a temporary seal as described herein. With tool  61  removed, contacts  262  of lead  265  are operably connected (e.g. electrically, optically, mechanically, and/or acoustically connected) to contacts  292  of attachment port  290 , such as to create an operable connection with one or more internal components of implantable assembly  200 . 
     In some embodiments, lead  265  is configured to be detached from implantable device  200  and subsequently operatively attached to implantable device  800  (e.g. in a second clinical procedure in which implantable device  800  is implanted). In some embodiments, lead  265  comprises a removable distal portion configured to subsequently attach to second implantable stimulator  800 , as described hereabove in reference to  FIG. 1C . 
     Referring now to  FIGS. 5A-B , top views of an apparatus comprising a temporary implantable device and an attachment lead for use in a trialing period is illustrated, consistent with the present inventive concepts. Implantable device  200  of  FIGS. 5A-B  is shown with the top portion of housing  210  removed for illustrative clarity. Apparatus  10  comprises implantable device  200 , lead  265 , and other components of similar construction and arrangement to those described hereabove in reference to  FIG. 1 . Implantable device  200  of  FIGS. 5  A-B comprises attachment port  290  which extends from the bottom to the top of implantable device  200 , such as to receive the proximal portion  268  of lead  265  including all contacts  262 . 
     Implantable device  200  includes a connecting and inserting component, sleeve  297   a , configured to slidingly engage attachment port  290 , such that proximal portion  268  can be positioned within sleeve  297   a  while sleeve  297   a  is in place within attachment port  290 . In some embodiments, sleeve  297   a  is positioned within attachment port  290 , after which lead  265  is inserted into sleeve  297   a . Alternatively, lead  265  can be inserted into attachment port  290 , after which sleeve  297   a  can be inserted between lead  265  and attachment port  290 . Sleeve  297   a  comprises connecting segments  297   b  (e.g. conductive material) which are positioned to align with contacts  262  of lead  265  and contacts  292  of attachment port  290 , such as to provide an operable connection between contacts  262  and contacts  292  when lead  265  and sleeve  297   a  are in place within implantable device  200 . 
     In some embodiments, sleeve  297   a  further comprises a compressible gasket, gasket  297   c . Gasket  297   c  can be fixedly attached to sleeve  297   a , or it can be a separate component as shown in  FIG. 5A . In some embodiments, gasket  297   c  is a separate component that is positioned about proximal portion  268  of lead  265 , after which it is inserted into sleeve  297   a  (which is already positioned in attachment port  290 ) or into attachment port  290  (after which sleeve  297   a  is inserted). Gasket  297   c  comprises connecting segments  297   d  (e.g. conductive material) which are positioned to align with connecting segments  297   b  of sleeve  297   a , contacts  262  of lead  265 , and contacts  292  of attachment port  290 , such as to provide an operable connection between contacts  262  and contacts  292  when lead  265 , sleeve  297   a , and gasket  297   c  are in place within implantable device  200  (as shown in  FIG. 5B ). 
     In some embodiments, lead  265  is configured to be detached from implantable device  200  and subsequently operatively attached to implantable device  800  (e.g. in a second clinical procedure in which implantable device  800  is implanted). In some embodiments, lead  265  comprises a removable distal portion configured to subsequently attach to second implantable stimulator  800 , as described hereabove in reference to  FIG. 1C . 
     Referring now to  FIGS. 6A-C , a side view, a sectional view, and a perspective view, respectively, of an attachment port of an implantable device are illustrated, consistent with the present inventive concepts. Apparatus  10  comprises implantable device  200 , lead  265 , and other components of similar construction and arrangement to those described hereabove in reference to  FIG. 1 . Implantable device  200  of  FIGS. 6  A-C comprises attachment port  290  which extends within implantable device  200 , such as to receive the proximal portion  268  of lead  265  including all contacts  262 . Attachment port  290  includes contacts  292 ′ comprising frictionally engaging contacts (e.g. brush-like contacts), such as electromechanical brushes used in electrical motors or any other common form of interference connector (e.g. canted springs, conductive mesh, deformable fingers, and the like). Contacts  292 ′ are each electrically attached to one or more electrical components of implantable device  200 , such as via electrical wires as shown. Attachment port  290  and contacts  292 ′ are configured to slidingly receive and frictionally engage proximal portion  268  of lead  265 , and to provide an electrical connection between contacts  262  and one or more electrical-based internal components of implantable device  200 . Attachment port  290  can include one or more gaskets, gasket  296  shown, to provide a seal around the entry point of lead  265  into attachment port  290 . Gasket  296  can also include one or more gaskets positioned between each of the adjacent contacts  292 ′, such as to minimize fluid conduction pathways between contacts  292 ′. 
     In some embodiments, lead  265  is configured to be detached from implantable device  200  and subsequently operatively attached to implantable device  800  (e.g. in a second clinical procedure in which implantable device  800  is implanted). In some embodiments, lead  265  comprises a removable distal portion configured to subsequently attach to second implantable stimulator  800 , as described hereabove in reference to  FIG. 1C . 
     Referring now to  FIGS. 7A-C , a side sectional view, a sectional view, and a perspective view, respectively, of an attachment port of an implantable device are illustrated, consistent with the present inventive concepts. Apparatus  10  comprises implantable device  200 , lead  265 , and other components of similar construction and arrangement to those described hereabove in reference to  FIG. 1 . Implantable device  200  of  FIGS. 7  A-C comprises attachment port  290  which extends within implantable device  200 , such as to receive the proximal portion  268  of lead  265  including all contacts  262 . Attachment port  290  includes rotating contacts  292 ″, each (four shown) comprising a hinge, an extension arm, and a conductive pin. The conductive pin of contacts  292 ″ are each electrically attached to one or more electrical components of implantable device  200 , such as via electrical wires as shown. Attachment port  290  is configured to slidingly receive proximal portion  268  of lead  265 , after which contacts  292 ″ can be rotated such that its pins frictionally engage and electrically connect to contacts  262  of lead  265 , providing an electrical connection between contacts  262  and one or more electrical-based internal components of implantable device  200 . The pins can pass through preformed holes (e.g. vias) and/or puncture through housing  210  in order to make the connection. Attachment port  290  can include one or more gaskets, gasket  296  shown, to provide a seal around the entry point of lead  265  into attachment port  290 . Gasket  296  can also include one or more gaskets positioned between each of the contacts  292 ″ to minimize fluid conduction pathways between contacts  292 ″. 
     In some embodiments, lead  265  is configured to be detached from implantable device  200  and subsequently operatively attached to implantable device  800  (e.g. in a second clinical procedure in which implantable device  800  is implanted). In some embodiments, lead  265  comprises a removable distal portion configured to subsequently attach to second implantable stimulator  800 , as described hereabove in reference to  FIG. 1C . 
     Referring now to  FIGS. 8A-C , a side view, a sectional view, and a perspective view, respectively, of an attachment port of an implantable device are illustrated, consistent with the present inventive concepts. Apparatus  10  comprises implantable device  200 , lead  265 , and other components of similar construction and arrangement to those described hereabove in reference to  FIG. 1 . Implantable device  200  of  FIGS. 8  A-C comprises attachment port  290  which extends within implantable device  200 , such as to receive the proximal portion  268  of lead  265  including all contacts  262 . Attachment port  290  includes spring-loaded contacts  292 ′″, each (four shown) comprising a conductive pin and a spring-like component configured to bias the pin in an extended position, as shown in  FIG. 8B . The conductive pin of contacts  292 ′″ are each electrically attached to one or more electrical components of implantable device  200 , such as via electrical wires as shown. 
     Attachment port  290  and contacts  292 ′″ are configured to slidingly receive proximal portion  268  of lead  265 . Once fully inserted, contacts  292 ′″ frictionally engage and electrically connect to contacts  262  of lead  265 , providing an electrical connection between contacts  262  and one or more electrical-based internal components of implantable device  200 . Attachment port  290  can include one or more gaskets, gasket  296  shown, to provide a seal around the entry point of lead  265  into attachment port  290 . Gasket  296  can also include one or more gaskets positioned between each of the contacts  292 ′″ to minimize fluid conduction pathways between contacts  292 ′″. 
     In some embodiments, lead  265  is configured to be detached from implantable device  200  and subsequently operatively attached to implantable device  800  (e.g. in a second clinical procedure in which implantable device  800  is implanted). In some embodiments, lead  265  comprises a removable distal portion configured to subsequently attach to second implantable stimulator  800 , as described hereabove in reference to  FIG. 1C . 
     Referring now to  FIGS. 9A-B , a side sectional view, and an end view, respectively, of an implantable device are illustrated, consistent with the present inventive concepts. Implantable device  200 , lead  265 , and other components of apparatus  10  can be of similar construction and arrangement to those described hereabove in reference to  FIG. 1 . Implantable device  200  of  FIGS. 9  A-B comprises attachment port  290  which extends within implantable device  200 , such as to receive the proximal portion of a lead  265  including all contacts  262  (not shown). Attachment port  290  includes spring-loaded contacts  292 , each (four shown) comprising a conductive segment electrically attached to one or more electrical components of implantable device  200 , such as via electrical wires as shown. 
     Attachment port  290  and contacts  292  are configured to slidingly receive proximal portion  268  of lead  265 . Once fully inserted, contacts  292  frictionally engage and electrically connect to contacts  262  of lead  265 , providing an electrical connection between contacts  262  and one or more electrical-based internal components of implantable device  200 . Contacts  262  can be of similar construction and arrangement to any of contacts  292 ′,  292 ″ and/or  292 ′″ described herein. Attachment port  290  further comprises compression element  293  which can be configured to compress (e.g. radially compress) attachment port  290  onto lead  265 , such as to provide a seal at the location in which lead  265  enters attachment port  290 . Alternatively or additionally, compression element  293  can be configured to create and/or improve the connection between contacts  262  and contacts  292 . In some embodiments, attachment port  290  includes one or more gaskets, gasket  296  shown, to provide and/or enhance the seal between lead  265  and attachment port  290 . Gasket  296  can also include one or more gaskets positioned between each of the contacts  292  to minimize fluid conduction pathways between contacts  292 . 
     In some embodiments, lead  265  is configured to be detached from implantable device  200  and subsequently operatively attached to implantable device  800  (e.g. in a second clinical procedure in which implantable device  800  is implanted). In some embodiments, lead  265  comprises a removable distal portion configured to subsequently attach to second implantable stimulator  800 , as described hereabove in reference to  FIG. 1C . 
     Referring now to  FIGS. 10A-B , perspective views of an implantable device prior to and after attachment to a lead, respectively, are illustrated, the implantable device comprising a rollable construction for surrounding the lead, consistent with the present inventive concepts. Implantable device  200  and lead  265  can be of similar construction and arrangement to those described hereabove in reference to  FIG. 1 . Implantable device  200  of  FIGS. 10A-B  comprises a flexible housing, housing  210 ″, which is configured to be rolled such that housing  210 ″ circumferentially surrounds lead  265  as shown in  FIG. 10B , where housing  210 ″ circumferentially surrounds lead  265 . Housing  210 ″ can comprise a flexible material and/or it can comprise multiple hinged sections configured to be pivoted (i.e. flexed) at each hinge section. 
     Implantable device  200  comprises contacts  292  (four shown) which are configured to operatively connect to corresponding contacts  262  (four shown) of lead  265 , such as to provide an electrical connection between contacts  262  and one or more electrical-based internal components of implantable device  200 . Contacts  262  can be of similar construction and arrangement to any of contacts  292 ′,  292 ″ and/or  292 ′″ described herein. In some embodiments, housing  210 ″ comprises an adhesive portion, portion  211  shown on the top side of housing  210 ″, which can be configured to maintain housing  210 ″ about lead  265  (e.g. prevent unrolling of housing  210 ″). 
     In some embodiments, attachment port  290  includes one or more gaskets, such as gasket  296  shown, to provide and/or enhance the seal between lead  265  and attachment port  290 . Gasket  296  can also include one or more gaskets positioned between each of the contacts  292  to minimize fluid conduction pathways between contacts  292 . 
     In some embodiments, lead  265  is configured to be detached from implantable device  200  and subsequently operatively attached to implantable device  800  (e.g. in a second clinical procedure in which implantable device  800  is implanted). In some embodiments, lead  265  comprises a removable distal portion configured to subsequently attach to second implantable stimulator  800 , as described hereabove in reference to  FIG. 1C . 
     Referring now to  FIGS. 11A-D , perspective views of various embodiments of a distal portion of a stimulation lead are illustrated, consistent with the present inventive concepts. Lead  265  can comprise chronically implantable lead, such as a lead configured to provide long term therapy (e.g. a lead implanted for at least one week, at least one month, and/or at least 6 months), and/or a test lead configured to be inserted in the patient for an acute period of time (e.g. to provide temporary stimulation for less than one hour, less than one day, and/or less than one week). For example, lead  265  can comprise a needle-like construction, with the distal portion  269  constructed and arrange to be temporarily inserted proximate one or more nerves to be stimulated by stimulation apparatus  10 , as described herein. In some embodiments, after implantation and/or while temporarily inserted, lead  265  can be used in a trialing procedure as described herebelow in reference to  FIG. 13 . 
     As described herebelow, lead  265  can comprise various configurations, such as varied constructions of its distal portion, such as distal portions  2691 - 2694  shown. The distal portions can each include one or more stimulation elements  260  configured to deliver energy to target tissue of a patient (e.g. one or more electrodes configured to deliver monopolar or bipolar electrical energy to tissue). Each lead  265  can comprise a proximal portion, such as proximal portions  2681 - 2683  as described herebelow in reference to  FIGS. 12A-C , or other proximal portion  268  described herein. The proximal portion of each lead  265  can include one or more contacts  262  configured to operably connect to a stimulation device (e.g. to provide an electrical connection between stimulation device  200 / 800  and one or more stimulation elements  260  such that energy provided by the stimulation device can be delivered by the stimulation elements  260 ). 
     As shown in  FIG. 11A , distal portion  2691  can comprise a flex circuit  2631  and a covering surrounding flex circuit  2631 , overmold  2611 . In some embodiments, one or more portions of overmold  2611  are removed (e.g. via a manufacturing process) to create one or more recesses  2612  to expose stimulation elements  260  configured to deliver energy to target tissue. Flex circuit  2631  can comprise one or more traces  2632  extending from the proximal portion of lead  265  to distal portion  2691  of lead  265 . Traces  2632  can operably connect stimulation elements  260  and contacts  262  (e.g. to provide an electrical connection between stimulation elements  260  and contacts  262 ). 
     As shown in  FIG. 11B , distal portion  2692  can comprise a conductive rod  2633  (e.g. a needle) with layer stack  2634  applied thereon (e.g. multiple layers applied to rod  2633 ). Layer stack  2634  can comprise alternating layers of an insulator  2635  and a conductor  2636 , with the outer most layer comprising insulator  2635 . The layers of insulator  2635  and conductor  2636  can be applied using one or more of the following deposition processes: sputtering; evaporation; dipping; plating; spraying; and chemical vapor deposition (CVD). In some embodiments, one or more portions of layer stack  2634  are removed (e.g. via a manufacturing process, such as laser ablation, wet etch, lift-off, etc.) to create one or more recesses  2612  to expose one or more portions of conductor  2636  and/or conductive rod  2633 . The exposed portions of conductor  2633  and/or conductive rod  2636  can comprise metalized contacts, stimulation elements  260  that are configured to deliver energy to target tissue. Conductive rod  2633  and/or conductor  2636  can operably connect to contacts  262  (e.g. to provide an electrical connection between stimulation elements  260  and contacts  262 ). 
     As shown in  FIG. 11C , distal portion  2693  can comprise one or more lumens  2613  extending from the proximal portion of lead  265  to distal portion  2693  of lead  265 . Lumens  2613  can surround one or more wires  2637  that operably connect stimulation elements  260  and contacts  262  (e.g. to provide an electrical connection between stimulation elements  260  and contacts  262 ). 
     As shown in  FIG. 11D , distal portion  2694  can comprise a needle-like construction, including (e.g. surrounding) one or more wires  2637  extending from proximal portion  268  to distal portion  2694  of lead  265 . Wires  2637  can operably connect stimulation elements  260  and contacts  262  (e.g. to provide an electrical connection between stimulation elements  260  and contacts  262 ). 
     Referring now to  FIGS. 12A-C , side views of various embodiments of a proximal portion of a stimulation lead are illustrated, consistent with the present inventive concepts. Lead  265  can comprise a chronically implantable lead, as described herein, and/or a test lead configured to be inserted in the patient for an acute period of time, as described herein. For example, lead  265  can comprise a needle-like construction, with its distal portion  269  constructed and arranged to be temporarily inserted proximate one or more nerves to be stimulated by stimulation apparatus  10 , as described herein. In some embodiments, after implantation and/or while temporarily inserted, lead  265  can be used in a trialing procedure as described herebelow in reference to  FIG. 13 . 
     As described herebelow, lead  265  can comprise various configurations, such as varied constructions of its proximal portion, such as proximal portions  2681 - 2683  as shown. The proximal portions can each include one or more contacts  262  configured to operably connect to a stimulation device (e.g. to provide an electrical connection between stimulation device  200 / 800  and one or more stimulation elements  260  such that energy provided by the stimulation device can be delivered by the stimulation elements  260 ). Each lead  265  can comprise a distal portion  269 , such as distal portions  2691 - 2694  as described hereabove in reference to  FIGS. 11A-C , or other distal portions  269  described herein. Distal portion  269  can include one or more stimulation elements  260  configured to deliver energy to target tissue of a patient (e.g. one or more electrodes configured to deliver monopolar or bipolar electrical energy). 
     As shown in  FIG. 12A , proximal portion  2681  can comprise one or more contacts  2621 . Contacts  2621  can be operably attached to conduit  263 . Contacts  2621  can each comprise a length of at least 0.07 inches. In some embodiments, contacts  2621  comprise a length greater than the length of contacts of commercially available stimulation leads, and/or contacts  2621  are otherwise sized such that a user can securely, repeatably, and/or reliably attach an alligator clip and/or other connection device to contact  2621  (e.g. minimizing the likelihood of connecting to an undesired contact of the lead). 
     A shown in  FIG. 12B , proximal portion  2682  can comprise one or more contacts  262  operably attached to conduit  263 . Proximal end  2682  can be operably insertable into a connector, such as attachment port  290  and/or  890  as described herein. Alternatively or additionally, proximal end  2682  can be operably attachable to an attachment mechanism, such as described herebelow in reference to  FIGS. 15A-E . 
     As shown in  FIG. 12C , proximal portion  2683  can comprise one or more contacts  262  that are operably attached to one or more connectors  2622 . Each connector  2622  can comprise an alligator clip or other electrically-connecting element. 
     Referring now to  FIG. 13 , a flow chart of a method of providing stimulation during a trialing procedure is illustrated, consistent with the present inventive concepts. The trialing procedure comprising method  3000  of  FIG. 13  can be accomplished with a stimulation device (e.g. stimulation device  200 / 800  described herein) and an implantable lead  265 . In STEP  3100 , lead  265  is implanted in the patient. In STEP  3200 , a stimulation device is connected to a first contact  262  of lead  265 . A trial period is initiated during which the stimulation device delivers stimulation energy with a minimum stimulation signal (e.g. a stimulation level at or close to 0). During STEP  3300 , the stimulation signal is increased, such as to achieve an optimized, or at least an improved, therapeutic benefit to the patient (e.g. increased pain relief). In STEP  3400 , once a desired therapeutic benefit is achieved (or a maximum stimulation level is reached with or without achieving a desired therapeutic benefit), the stimulation signal is decreased to the minimum stimulation signal. In STEP  3500 , the stimulation device is disconnected from the first contact  262  and subsequently connected to a second contact  262 . A trial period is initiated during which the stimulator delivers stimulation energy with the minimum stimulation signal. STEPS  3300  through  3500  can be repeated with additional contacts  262  to achieve an optimized therapeutic benefit to the patient. 
     After completion of STEP  3400  for the final contact  262  (e.g. each contact  262  has delivered trialing stimulation), if adequate therapy is achieved (e.g. an optimized, desired, and/or otherwise adequate therapy is achieved), long-term therapy can be implemented with implantable device  200 / 800  and lead  265  using the optimized stimulation signals identified in method  3000 . 
     Referring now to  FIGS. 14A-D , side views of an implantable system comprising a short-term (temporary) implantable device with an integrated lead, and a lead removal tool are illustrated, consistent with the present inventive concepts. The lead removal tool is used to remove the lead from the short-term implantable device for subsequent use with a long-term implantable device. The short-term implantable device can comprise implantable device  200 , as described hereabove, such as to provide temporary stimulation therapy, as described hereabove. The long-term implantable device can comprise implantable device  800 , such as to provide long-term stimulation therapy to the patient, also as described hereabove. 
     As shown in  FIG. 14A , implantable device  200  and lead  265  are integrated (e.g. lead  265  is fixedly attached to implantable device  200 , such as during a manufacturing process). Implantable device  200  can be operably attached via one or more wires  294  to one or more stimulation elements  260  of lead  265 . Lead  265  comprises one or more contacts  262  which are similarly connected to stimulation elements  260 . Contacts  262  can be covered by an insulating material, insulator  66 , which can comprise a passivation layer applied to contacts  262  and/or an insulating sleeve. In some embodiments, implantable device  200  and lead  265  are operably attached via connector  66 . Insulator  66  can extend from the most proximal contact  262  to the most distal contact  262 . Insulator  66  can be configured to be removed, such as via a peeling process, to expose contacts  262 , as described herebelow. 
     As shown in  FIG. 14B , a tool  62  can slidingly receive implantable device  200  through an opening  63 . In some embodiments, opening  63  can include one or more projections  64 . Projections  64  can be configured to engage lead  265  at a pre-determined location, as indicated by a marker  68  on proximal portion  268  of lead  265 . In some embodiments, marker  68  is positioned at a weakened portion of lead  265 . 
     As shown in  FIG. 14C , in response to an external force, projections  64  can travel inward and frictionally engage lead  265  at marker  68 , to separate lead  265  from implantable device  200  (e.g. to sever and/or cause a break in lead  265 ). In some embodiments, insulator  66  is removed to expose contacts  262 . Implantable device  200  (e.g. including a portion of wires  294 ), can be removed and replaced with implantable device  800 , as shown in  FIG. 14D . Implantable device  800  can slidingly receive the proximal portion (e.g. the remaining proximal portion) of lead  265 , including contacts  262  (e.g. lead proximal portion  268 ). Contacts  262  each align with and operably engage associated contacts  892  of device  800 , similar to as described hereabove in reference to  FIG. 1 . 
     Referring now to  FIGS. 15A-E , a perspective view of a stimulator and a lead attachment assembly, and various close-up views of an attachment mechanism of the attachment assembly, are illustrated, consistent with the present inventive concepts. Attachment assembly  650  can comprise an attachment mechanism  655 , and can be used to attach a lead  265  to a stimulation device  600 . Stimulation device  600  can be configured to provide stimulation energy to lead  265  (similar to implantable devices  200 / 800 ), and it can include a user interface (e.g. similar to devices  500 / 550 ). In some embodiments, stimulation device  600  receives commands (e.g. wirelessly receives commands) from devices  500 / 550 . 
     As shown in  FIG. 15A , stimulator device  600  can include a conduit  601  (e.g. a conduit including one or more wires) with a distal end connector, connector  602 . Attachment assembly  650  can include a conduit  651  with a proximal end connector, connector  652 . In some embodiments, connectors  602 , 652  comprise pig-tail connectors configured to operably connect stimulation device  600  and attachment assembly  650 . Attachment assembly  650  can comprise an attachment mechanism  655  with a base portion, base  656 , and one or more hinged portions, clip  657 . 
     Base  656  can include one or more contacts  659  operably connected to conduit  651  (e.g. to provide an electrical connection between wires of conduit  651  and contacts  659 ). Base  656  can slidingly receive and/or rotatably engage a portion of clip  657 , such that attachment mechanism  655  can transition from an open configuration (as shown in  FIGS. 15D  and E) to a closed configuration (as shown in  FIGS. 15B  and C). 
     As shown in  FIG. 15B , clip  657  can comprise a first recess  658  configured to slidingly receive a portion of lead  265 , including contacts  262 . In the closed configuration, contacts  659  can extend into recess  658  and operably connect (e.g. at least electrically connect) to contacts  262  of an inserted lead  265  (e.g. to provide at least an electrical connection between contacts  262  and  659 ). For example, lead  265  can be inserted into recess  658  when attachment mechanism is in an open configuration, and clip  657  can subsequently be “closed”, locking lead  265  within recess  658 , allowing contacts  262  and  659  to operably engage. 
     As shown in  FIGS. 15C  and D, attachment mechanism  655  can transition between an open configuration and a closed configuration (the open configuration shown in  FIG. 15D ). Base  656  and clip  657  can be configured to interlock (e.g. releasably interlock) in the closed configuration, thereby securing a portion lead  265  within attachment mechanism  655 . Base  656  can include a projection  6561  configured to frictionally engage a second recess  6562  of clip  657 . In some embodiments, attachment mechanism transitions from the open configuration to the closed configuration when clip  657  is depressed by a user (e.g. projection  6561  engages recess  6562 ). In other embodiments, attachment mechanism  655  transitions from the closed configuration to the open configuration when clip  657  is elevated by a user (e.g. projection  6561  disengages from recess  6562  when clip  657  is lifted away from base  656 ). 
     As shown in  FIG. 15E , clip  657  can be configured to abut another portion of attachment mechanism  655 , such as to limit the elevation of clip  657  relative to base  656 . In some embodiments, attachment assembly  650  can comprise a functional element  699 . Functional element  699  can comprise a sensor, configured to detect a proper (or improper) connection of a lead  265  to attachment mechanism  655  (e.g. via an impedance measurement). Additionally or alternatively, functional element  699  can comprise a transducer, such as a speaker. For example, functional element can be configured to alert the user via an audible alarm if lead  265  is dislodged from attachment mechanism  655 . In some embodiments, stimulator  600  comprises functional element  699 . 
     While the preferred embodiments of the devices and methods have been described in reference to the environment in which they were developed, they are merely illustrative of the principles of the present inventive concepts. Modification or combinations of the above-described assemblies, other embodiments, configurations, and methods for carrying out the invention, and variations of aspects of the invention that are obvious to those of skill in the art are intended to be within the scope of the claims. In addition, where this application has listed the steps of a method or procedure in a specific order, it may be possible, or even expedient in certain circumstances, to change the order in which some steps are performed, and it is intended that the particular steps of the method or procedure claim set forth herebelow not be construed as being order-specific unless such order specificity is expressly stated in the claim.