Patent Publication Number: US-2022212006-A1

Title: Microstimulation sleep disordered breathing (sdb) therapy device

Description:
CROSS-REFERENCE 
     This application is a continuation of U.S. application Ser. No. 15/774,471, filed May 8, 2018, which is a National Stage Application of, and that claims priority to, PCT Application No. PCT/US2016/062546, entitled “MICROSTIMULATION SLEEP DISORDERED BREATHING (SDB) THERAPY DEVICE” having a filing date of Nov. 17, 2016, which claims the benefit of U.S. Provisional Patent Application No. 62/256,680, entitled “MICROSTIMULATION SLEEP DISORDERED BREATHING (SDB) THERAPY DEVICE,” having a filing date of Nov. 17, 2015, all of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     Treating sleep disordered breathing has led to improved sleep quality for some patients. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram schematically representing a microstimulation therapy device as implanted within a patient&#39;s body, according to one example of the present disclosure. 
         FIG. 2  is a block diagram schematically representing an implanted microstimulation therapy device, according to one example of the present disclosure. 
         FIG. 3  is a block diagram schematically representing a microstimulation therapy device juxtaposed relative to a nerve, according to one example of the present disclosure. 
         FIG. 4  is a block diagram schematically representing a microstimulation therapy device juxtaposed relative to a nerve, according to one example of the present disclosure. 
         FIG. 5  is a block diagram schematically representing a microstimulator of microstimulation therapy device, according to one example of the present disclosure. 
         FIG. 6A  is a block diagram schematically representing a power element, according to one example of the present disclosure. 
         FIG. 6B  is a block diagram schematically representing an energy harvesting arrangement, according to one example of the present disclosure. 
         FIG. 6C  is a diagram schematically representing at least a charging station in association with a patient support, according to one example of the present disclosure. 
         FIG. 7  is a block diagram schematically representing a communication element, according to one example of the present disclosure. 
         FIG. 8  is a diagram schematically representing a microstimulator of a microstimulation therapy device including a sensing function, according to one example of the present disclosure. 
         FIG. 9A  is a block diagram schematically representing a sensor, according to one example of the present disclosure. 
         FIG. 9B  is a block diagram schematically representing different sensing arrangements, according to one example of the present disclosure. 
         FIG. 10  is a block diagram schematically representing sensor types, according to one example of the present disclosure. 
         FIG. 11  is a diagram schematically representing a sensor array implanted in a head/neck region, according to one example of the present disclosure. 
         FIG. 12  is a block diagram schematically representing mechanical coupling arrangements, according to one example of the present disclosure. 
         FIG. 13  is a block diagram schematically representing electrical coupling arrangements, according to one example of the present disclosure. 
         FIG. 14A  is a diagram schematically representing a microstimulation therapy device implanted relative to a nerve, according to one example of the present disclosure. 
         FIG. 14B  is a sectional view schematically representing the implanted microstimulation therapy device of  FIG. 14A , according to one example of the present disclosure. 
         FIG. 14C  is a block diagram schematically representing information regarding the implanted microstimulation therapy device of  FIG. 14A , according to one example of the present disclosure. 
         FIG. 15A  is a diagram schematically representing a microstimulation therapy device implanted relative to a nerve, according to one example of the present disclosure. 
         FIG. 15B  is a sectional view schematically representing the implanted microstimulation therapy device of  FIG. 15A , according to one example of the present disclosure. 
         FIG. 15C  is a block diagram schematically representing information regarding the implanted microstimulation therapy device of  FIG. 15A , according to one example of the present disclosure. 
         FIG. 16A  is a diagram schematically representing a microstimulation therapy device implanted relative to a nerve, according to one example of the present disclosure. 
         FIG. 16B  is a sectional view schematically representing the implanted microstimulation therapy device of  FIG. 16A , according to one example of the present disclosure. 
         FIG. 17A  is a diagram schematically representing a microstimulation therapy device implanted relative to a nerve, according to one example of the present disclosure. 
         FIG. 17B  is a sectional view schematically representing the implanted microstimulation therapy device of  FIG. 17A , according to one example of the present disclosure. 
         FIG. 17C  is a perspective view schematically representing a helically-shaped flange of the therapy device of  FIG. 17A-17B , according to one example of the present disclosure. 
         FIG. 17D  is a sectional view as taken along lines  17 D- 17 D of  FIG. 17C  and schematically representing an axial array of electrodes, according to one example of the present disclosure. 
         FIG. 18A  is a diagram schematically representing a microstimulation therapy device implanted relative to a nerve, according to one example of the present disclosure. 
         FIG. 18B  is a perspective view schematically representing the microstimulation therapy device of  FIG. 18A , according to one example of the present disclosure. 
         FIG. 18C  is a sectional view schematically representing the implanted microstimulation therapy device of  FIG. 18A , according to one example of the present disclosure. 
         FIG. 19A  is a perspective view schematically representing an electrode cuff of a stimulation therapy device, according to one example of the present disclosure. 
         FIG. 19B  is a sectional view as taken along lines  19 B- 19 B in  FIG. 19A , which schematically represents a cuff electrode, according to one example of the present disclosure. 
         FIG. 19C  is a sectional view as taken along lines  19 C- 19 C in  FIG. 19A , which schematically represents a cuff electrode, according to one example of the present disclosure. 
         FIG. 20A  is a perspective view schematically representing an electrode cuff for a stimulation therapy device, according to one example of the present disclosure. 
         FIG. 20B  is a perspective view schematically representing an electrode cuff for a stimulation therapy device, according to one example of the present disclosure. 
         FIG. 20C  is a partial end view schematically representing an electrode cuff, according to one example of the present disclosure. 
         FIG. 21A  is a diagram schematically representing a microstimulation therapy device, according to one example of the present disclosure. 
         FIG. 21B  is a diagram schematically representing an implanted microstimulation therapy device secured relative to a bony structure, according to one example of the present disclosure. 
         FIG. 22  is a diagram schematically representing antenna arrangements associated with a microstimulation therapy device, according to one example of the present disclosure. 
         FIG. 23A  is a diagram schematically representing a microstimulation therapy device implanted within at least a portion of the vasculature, according to one example of the present disclosure. 
         FIG. 23B  is a diagram schematically representing a microstimulation therapy device implanted within at least a portion of the vasculature, according to one example of the present disclosure. 
         FIG. 24  is a block diagram schematically representing a therapy manager, according to one example of the present disclosure. 
         FIG. 25A  is a block diagram schematically representing a control portion, according to one example of the present disclosure. 
         FIG. 25B  is a block diagram schematically representing a user interface, according to one example of the present disclosure. 
         FIG. 26  is a flow diagram schematically representing aspects associated with a method for microstimulation, according to one example of the present disclosure. 
         FIG. 27  is a block diagram schematically representing aspects associated with a method for microstimulation, according to one example of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following Detailed Description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific examples of the present disclosure which may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “leading,” “trailing,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of at least some examples of the present disclosure can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other examples may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense. 
     In at least some examples of the present disclosure, an implantable microstimulation therapy device is employed in association with a therapy for sleep disordered breathing. In some examples, the microstimulation therapy device includes a microstimulator defining a housing sized (e.g. a volume) and/or shaped to facilitate a minimally invasive implantation that is performed in close proximity to a nerve to be stimulated by the microstimulator. In some examples, at least the housing of the microstimulator has a volume and a shape to enable the microstimulator to be secured directly against the nerve to be stimulated. In some examples, an electrode structure extends from the housing and is also directly secured against, or at least coupled relative to, the nerve to be stimulated. 
     In some examples, a housing of the microstimulator has a volume and a shape to enable the microstimulator to be secured against or relative to other body structures in proximity to the nerve to be stimulated while circuitry within the housing is electrically coupled relative to the nerve via an electrode structure extending outwardly from a housing of the microstimulator. 
     With this in mind, the terms “microstimulation” and/or “microstimulator” refer to the size (e.g. including but not limited to volume) and/or shape of a housing of a therapy device which enable its placement in a minimally invasive manner and/or fixation in close proximity to a target nerve. In some examples, a microstimulator is sized and/or shaped to be fully implantable via a single incision. In some examples, the single incision is located in a head/neck region of the patient. In some examples, the housing of the microstimulator has a volume at least one order of magnitude less than a volume of commercially available, pectorally implantable pulse generator, such as traditional pacemakers, cardio-defibrillators, etc. In some examples, the housing of the microstimulator has a volume at least two orders of magnitude less than a volume of commercially available, pectorally implantable pulse generator, such as traditional pacemakers, cardio-defibrillators, etc. 
     In some examples, an outer surface of the housing of the microstimulator is electrically nonconductive such that even direct contact against the target nerve does not electrically couple circuitry within the microstimulator relative to the target nerve. Instead, such electrical coupling is implemented via an electrode structure extending outwardly from the housing of the microstimulator. However, in some examples, at least one electrically conductive element is present on the outer surface of the housing of the microstimulator such that direct contact against the target nerve does at least partially electrically couple the circuitry within the microstimulator relative to the target nerve. 
     In some examples, the microstimulator is implanted via nonvascular techniques and/or implanted in a subcutaneous location which is also extravascular, i.e. not within the vasculature (e.g. veins, arteries), cardiac structures, etc. In some examples, the microstimulator is implanted in a head/neck region, which is non-pectoral and as such also is a non-cardiac implantation. 
     These examples, and additional examples, are described in more detail in association with at least  FIGS. 1-27 . 
       FIG. 1  is diagram schematically representing a patient environment  20  including a patient  22  having a microstimulation therapy device  32  implanted within a head/neck region  24  of the patient, according to one example of the present disclosure. As shown in  FIG. 1 , in some examples, therapy device  32  is implanted subcutaneously in proximity to a target nerve  30 . Stimulation of the target nerve  30  via therapy device  32  causes contraction of at least some muscles innervated via the target nerve  30 . In some examples, the target nerve  30  and associated muscle(s) are associated with maintaining and/or restoring patency of the upper airway  36 . Various aspects regarding the implantation and deployment of microstimulation therapy device  32  are described in association with at least  FIGS. 2-25 . 
       FIG. 2  is a diagram of a patient environment  50  in the head/neck region  24  ( FIG. 1 ), according to one example of the present disclosure. As shown in  FIG. 2 , in some examples therapy device  32  (e.g. a microstimulator device) is sized and/or shaped to be fully implanted within a subcutaneous environment  74  below at least the skin  70  through a single incision  72 . Accordingly,  FIG. 2  at least partially illustrates and represents the result of a minimally invasive implantation of therapy device  32  via a percutaneous pathway, non-vascular pathway, or analogous technique to place therapy device  32  in proximity to target nerve  30 . 
     This arrangement avoids several factors associated with implantation of a commercially available, pectorally implanted pulse generator and associated leads. For instance, such pectoral implantation involves more incisions, creating a pouch in the body to receive the pulse generator, tunneling a path for a lead to extend from the pulse generator to the target nerve, etc. While generally effective, such procedures involve a larger surgical field, more incisions, a long duration surgical event, etc. Moreover, because the lead will extend from the pectoral region into and through substantially the entire neck region, the lead may be subject to stresses and/or stability challenges associated with normal movements of the neck. Both the implantation and/or location of these various elements may contribute to patient comfort and long term effectiveness. 
     Accordingly, via at least some examples of the present disclosure, a minimally invasive implantation technique is implemented, thereby avoiding a number of challenges posed by pectoral implantation techniques of a pulse generator and associated lead(s). 
     In addition, in some examples, employing a minimally invasive implant procedure in a head/neck region in proximity to the target nerve to be stimulated, with the implant comprising a relatively small microstimulation therapy device locatable in proximity to the target nerve, may enable increased patient eligibility for receiving magnetic resonance imaging (MRI). For instance, in such examples, the patient may be eligible for a body coil MR scan since no components of the microstimulation therapy device would be present in the torso. This arrangement stands in sharp contrast to at least some commercially available pectorally implanted therapy devices, which may prohibit such body coil MR scans. As such, at least some examples of the present disclosure may enable the microstimulation therapy device to be eligible to labeled as conditionally acceptable for a body coil MR scan or other limited form of MR imaging. 
     With further reference to at least  FIGS. 1-2 , in some examples, such as the case of obstructive sleep apnea, the nerve(s)  30  may include (but are not limited to) the nerve(s) and muscles related to causing movement of the tongue and related musculature to restore upper airway patency. In some examples, the nerve(s)  30  may include (but are not limited to) the hypoglossal nerve and the muscles may include (but are not limited to) the genioglossus muscle. 
     As further shown in  FIG. 2 , microstimulation therapy device  32  is coupled (via coupling  62 ) relative to target nerve  30  within the subcutaneous environment  74 . Notably, with the subcutaneous environment  74  being in the head/neck region  24 , complications associated with a cardiac environment are avoided. Moreover, the microstimulation therapy device  32  is implanted in an extravascular manner, i.e. without the complications of introducing and delivering a device into and through the vasculature of the body. 
     In some examples, the microstimulation therapy device  32  is mechanically coupled relative to the nerve  30 , thereby at least partially securing the therapy device  32  within the subcutaneous environment  74 . At least some specific examples of such mechanical coupling are shown and described later in association with at least  FIGS. 12 and 14A-18D . 
     In some examples, the microstimulation therapy device  32  is electrically coupled relative to the nerve  30 , thereby at least partially electrically coupling the therapy device  32  relative to the nerve  30  within the subcutaneous environment  74 . At least some specific examples of such electrical coupling are shown and described later in association with at least  FIGS. 13 and 14A-18D . 
     In some examples, such mechanical coupling and electrical coupling may be implemented via a single element or via multiple elements, with some elements providing both mechanical and electrical coupling. 
       FIG. 3  is a block diagram schematically representing a therapy arrangement  80 , according to one example of the present disclosure. As shown in  FIG. 3 , in arrangement  80 , the microstimulation therapy device  32  is directly coupled relative to the nerve  30 . In some examples, such coupling includes a direct mechanical coupling without a direct electrical coupling. In some examples, such coupling includes a direct mechanical coupling and a direct electrical coupling. At least some instances of the arrangement  80  are shown and described later in association with at least  FIGS. 12-13 and 14A-18D . 
       FIG. 4  is a block diagram schematically representing a therapy arrangement  90 , according to one example of the present disclosure. As shown in  FIG. 4 , in arrangement  90 , the microstimulation therapy device  32  is not directly coupled relative to the nerve  30 . In some examples, such coupling includes an indirect electrical coupling of the therapy device  32  and nerve  30 . For instance, in some examples, the indirect electrical coupling includes circuitry within therapy device  32  being electrically coupled to the nerve  30  via conductive elements located at some distance from a surface of a housing of the therapy device. In some examples, such coupling includes an indirect mechanical coupling of therapy device  32  relative to nerve  30  via the therapy device mechanically engaging at least some portion of the subcutaneous environment  74  other than nerve  30 . At least some instances of the arrangement  90  are shown and described later in association with at least  FIGS. 12-13 and 14A-18D . 
     With this general arrangement of  FIGS. 1-4  in mind, it will be understood that at least some implementations associated with  FIGS. 5-25  provide more specific examples of various implementations and details regarding the operation and interaction of at least some aspects of a microstimulation therapy device relative to a target nerve  30 . 
     Moreover, at least some examples of the present disclosure result in a more comfortable placement of the therapy device than commercially available injectable stimulators. In addition, at least some example therapy devices of the present disclosure are more securely fixed in place within the patient&#39;s body than a commercially available injectable stimulator, which tend to migrate within the patient&#39;s body. In another aspect, applying nerve stimulation via at least some examples of the present disclosure enhances patient comfort as compared to at least some commercially available direct muscle stimulators, which may tend to inhibit patient comfort and/or which may ineffectively engage the patient anatomy. 
       FIG. 5  is a block diagram schematically representing a microstimulation therapy device  100 , according to one example of the present disclosure. In some examples, therapy device  100  comprises at least some of substantially the same features and attributes as the previously described microstimulation therapy devices and arrangements ( 32  in  FIGS. 1-4 ). 
     As shown in  FIG. 5 , therapy device  100  includes power element  110 , stimulation circuitry  112 , communication element  114 , and a control portion  120  having therapy manager  122 . In some examples, the control portion  120  comprises at least some of substantially the same features and attributes as control portion  1700  as described in association with  FIG. 25A  and/or therapy manager  122  comprises at least some of substantially the same features and attributes as therapy manager  1705  as described in association with  FIG. 25A  (or therapy manager  1600  in  FIG. 24 ). 
     In some examples, power element  110  provides power for the operation of microstimulation therapy device  100 . At least some aspects of power element  110  are further described later in association with at least  FIG. 6A . 
     In some examples, stimulation circuitry  112  can generate electrical signals deliverable through a stimulation element suitable for exciting a target nerve associated with muscles that can restore airway patency. In some examples, stimulation circuitry  112  produces at least substantially the same type and manner of stimulation signals as a commercially available implantable pulse generator, but with therapy device  100  having a substantially smaller size and/or shape as previously noted. For instance, in some examples, the therapy device  100  (including stimulator circuitry  112 ) has a volume at least one order of magnitude less than a volume of a commercially available implantable pulse generator (IPG) which is used for treating sleep disordered breathing and which is implanted at a pectoral location. In some examples, therapy device  100  has a volume at least two orders of magnitude less than a volume of such commercially available, pectorally implantable pulse generators. 
     In some examples, the signals are adapted to directly stimulate nerve  30  innervating upper-airway-related muscles. In some examples, such as the case of obstructive sleep apnea, the nerves  30  may include (but are not limited to) the nerve  30  and associated muscles responsible for causing movement of the tongue and related musculature to restore airway patency. In some examples, the nerves  76  may include (but are not limited to) the hypoglossal nerve and the muscles may include (but are not limited to) the genioglossus muscle. 
     With further reference to  FIG. 5 , in some examples communication element  114  enables at least some of the components of microstimulation therapy device  100  to communicate with devices, components, modules, etc. which are external to therapy device  100 , whether such devices, components, modules, etc. are located elsewhere within the patient&#39;s body and/or located external to the patient&#39;s body. At least some aspects of the communication element  114  are further described later in association with at least  FIG. 7 . 
     In some examples, a therapy manager  122  comprises part of or is incorporated within the therapy device  100 , such as being part of control portion  120 . As such, therapy manager  122  is “on board” the therapy device  100 . In some examples, a therapy manager is external to the therapy device  100  but is at least intermittently coupled to and/or in communication with the on-board therapy manager  122 . In some examples, therapy manager  122  implements sleep disordered breathing (SDB) stimulation therapy but, as part of control portion  120 , is also responsible for managing at least some general operations of therapy device  100 . 
       FIG. 6A  is a block diagram schematically representing the power element  110 , according to one example of the present disclosure. As represented in  FIG. 6A , in some examples power element  110  may be implemented via at least one of various power modalities such as a rechargeable modality  140 , a storage modality  142 , and/or an energy harvesting modality  144 . 
     In some examples, the rechargeable modality  140  employs a handheld battery-operated charger external to the patient&#39;s body. On a periodic basis, the charger is placed in close proximity to the implanted microstimulation therapy device  100  to apply a fast charging protocol to ensure the therapy device  32  has sufficient power for implementing the therapy overnight. In some examples, the periodic basis is daily, weekly, or monthly. 
     In some examples, the rechargeable modality  140  includes an inductive element (e.g. antenna) within or associated with the microstimulation therapy device  100  and via a magnetic alignment of an antenna within the handheld charger, energy is transferred from the charger to the power element  110  within the therapy device  100 . In some examples, the rechargeable modality  140  employs piezoelectric transducer(s) associated with the power element  110  to affect an ultrasonic energy transfer from the handheld charger to the power element  110  within the therapy device  100 . 
     In some examples, the rechargeable modality  140  involves generally continuous charging in which an object in the patient&#39;s sleep environment (such as a pillow, bed, garment, etc.) includes a power source/element having an antenna to implement energy transfer to the power element  110  within the therapy device  100 . In some examples, the power element  110  includes multiple antennas, each oriented in a different direction or position, and the external object (e.g. pillow, bed, etc.) includes multiple antennas oriented in different directions or positions, thereby reducing alignment sensitivity of the charging elements. In one aspect, this form of generally continuous charging is sometimes referred to as an automatic charging mode. 
     In some examples, the power element  110  includes a rectenna, which is a form of antenna that receives electromagnetic waves (e.g. radiofrequency waves) applied via an external device and converts those waves into direct current electricity for use by the therapy device  110 . 
     It will be understood that in at least some of the various examples of the rechargeable modality  140 , the power element  110  includes at least some short-term energy storage capability sufficient to enable stimulation therapy for at least one treatment period (e.g. a daily sleep period). 
     As further shown in  FIG. 6A , in some examples the power element  110  comprises a storage modality  142 . In some examples, the energy storage modality  142  is implemented via a long term rechargeable battery, such as but not limited to, a Lithium-Ion battery having high energy density. In some examples, the energy storage modality  142  is implemented via a supercapacitor, which provides a high charge rate and low mass, enabling a fast charging protocol of rechargeable modality  140 . 
     As further shown in  FIG. 6A , in some examples power element  110  comprises an energy harvesting modality  144 . In some examples, the energy harvesting modality  144  is implemented via a thermopile-based energy harvester. In some examples, the energy harvesting modality  144  is implemented via a piezoelectric motion/deflection technique. In some instances, the energy harvesting modality  144  may enable the power element  110  to be referred to as an on-board power source (e.g. on-board power generation element), thus freeing the therapy device  100  from having to be recharged via sources external to the body via rechargeable modality  140 . Accordingly, in some examples, the energy harvesting modality  144  may sometimes be referred to as a non-rechargeable modality because instead of re-charging a depleted power element, new power is generated (e.g. energy harvesting) on-board the stimulator. Stated differently, via energy harvesting modality  144 , therapy device  100  may operate without involving any external charging. 
     In some examples, the therapy device  100  may combine various aspects of the different modalities  140 ,  142 ,  144 . 
     Via at least some of the examples of the present disclosure, expensive recharging of a power element  110  of a therapy device is at least minimized or avoided and/or typical patient non-compliance with recharging is at least minimized or avoided. Moreover, in some examples, some of the more bulky components associated with traditional recharging schemes may be minimized and/or avoided, thereby facilitating a minimally invasive implantation and/or minimal profile within the subcutaneous environment (which in turn enables direct placement in close proximity to a target nerve). 
       FIG. 6B  is a block diagram schematically representing a power element arrangement  150 , according to one example of the present disclosure. In some examples, power element arrangement  150  provides one example implementation of power element  110  and at least energy harvesting modality  144  in  FIG. 6A . As shown in  FIG. 6B , in some examples the power element arrangement  150  comprises a power element  152 , which includes an energy harvesting element  154 , mass  160 , and energy storage element  162 . 
     In some examples, the energy harvesting element  154  comprises a mechanical energy harvesting element. In some examples, the energy harvesting element  154  comprises a piezoelectric capacitor element  156  while in some examples, the energy harvesting element  154  comprises a microelectromechanical system (MEMS) capacitor element  158 . In some examples, the MEMS capacitor element  158  comprises a MEMS electret capacitor. In some examples, the energy harvesting element  154  comprises an element other than piezoelectric capacitor and/or MEMS capacitor to harvest mechanical energy. 
     In some examples, the energy harvesting element  154  is associated with, is operably coupled to, and/or comprises mass  160 . In some such examples, one side of the energy harvesting element  154  (e.g. piezoelectric capacitor or MEMS capacitor) is directly mechanical coupled to a stimulator (to provide power), while the other side of the energy harvesting element  154  is directly mechanically coupled to mass  160 . Via such arrangement, mechanical vibrations, mechanical stress, and/or mechanical strain is converted via the energy harvesting element  154  (in association with mass  160 ) into electrical energy which is then transferred to the stimulator and/or stored in energy storage element  162 , as shown in  FIG. 6B . 
     In some examples, energy storage element  162  comprises a battery  164 , a capacitor  166 , and/or other storage modality  168 . 
     The power element  152  comprises is implantable ( 157 B) within a patient&#39;s body, at least below skin  157 A. In some examples, the power element  152  may be at least partially contained within or otherwise incorporated with another implantable component, such as a housing of a stimulator or therapy device. 
     In some examples, the power element arrangement  150  comprises components external ( 157 C) to skin  157 C, and selectively operably coupled relative to the implantable power element  152 . In some examples, the external components may comprise an external power element  170  which provides a supplemental or alternate source of power or energy to implantable components. In some examples, the external power element  170  comprises a battery  172  (which may be permanent or rechargeable), a line voltage  174 , and/or other power source  176 . In some instances, a control portion or a patient may select the stimulator ( 100 ,  200  in  FIGS. 5, 8 ) to receive power from external power element  170  prior to a treatment period (e.g. sleep period) if recent energy harvesting has been insufficient to provide sufficient energy for an upcoming treatment period. 
     In some examples, external components associated with power element arrangement  150  may include a coupling element  180  to facilitate operable coupling of external power element  170  relative to the implantable components, e.g. power element  152 . In general terms, the coupling element  180  can take a wide variety of forms, which may indirectly couple the external power element  170  through tissue to the implantable power element  152 . In some examples, the coupling element  180  comprises an ultrasonic transducer  182  while in some examples, the coupling element  180  comprises other forms  184  of indirect coupling. 
       FIG. 6C  is a side plan view schematically representing a nerve stimulation system  2600  for treating sleep disordered breathing (SDB), such as obstructive sleep apnea, according to one example of the present disclosure. As shown in  FIG. 6C , in some examples system  2600  may provide therapy to a patient  26002  reclined on a support  2604 . The patient support  2604  may comprise a bed  26005  and/or a headrest structure  2006  (e.g., pillow, neck support, etc). In some examples, the patient support  2604  houses at least power source  2600 . In some examples, the patient support  2604  also houses and/or provides radiofrequency transmission coils  2620 . 
     It will be understood that patient support  2604  is not strictly limited to a bed and/or pillow, but extends to other configurations in which the patient  2602  can remain stationary for an extended period of time. 
     As further illustrated in  FIG. 6C , system  2600  includes a microstimulator  2635  which is implanted within the patient&#39;s body. In some examples, the microstimulator  2035  is implanted in the patient&#39;s head-neck region. In one aspect,  FIG. 6C  also depicts microstimulator  2635  in block diagram form (labeled as  2610 ). In some examples, microstimulator  2635  comprises any one of the stimulators (e.g. at least  100 ,  200  in  FIG. 5, 8 ) and associated electrodes, cuffs, housings, flanges, etc. in any of the various forms as described throughout the examples of the present disclosure in association with  FIGS. 1-27 . 
     Referring again to  FIG. 6C , in some examples system  2600  also includes at least one sensor arrangement  2680 . The sensor arrangement  2680  may comprise a single sensor or multiple sensors as implemented via at least one of the sensors (e.g. types of sensors, sensing arrangements, etc.) as previously described in association with at least sensors  210  in  FIG. 9A, 250  in  FIG. 9B , and/or  300  in  FIG. 10 . As further described later, sensed information obtained via the sensor arrangement  2680  may be communicated to the implanted microstimulator  2635  via at least a sensor information transmission function  2670  of the charging station  2650 . 
     As just one example of the many different forms and modes of sensing via sensor arrangement,  FIG. 6C  schematically represents at least some aspects of external sensing. In some examples, such sensing may be suitable for detection of an apnea and for triggering application of the stimulation signal synchronous with respiration, such as with inspiration. However, it will be understood that the sensed information may be used for other purposes and does not necessitate closed loop operation of the system  2600 . Accordingly, in some examples, at least some sensing is provided via an externally securable belt  2630  including a wearable, external sensor  2631 . In some examples, signals sensed at sensor  2631  are transmitted wirelessly to a control portion (e.g.  1700  in  FIG. 25B ) for use in apnea detection and treatment, etc. In some examples, the control portion  1700  is associated with, incorporated with, and/or coupled to power element  2622 . 
     In some examples, sensing is provided via a sensor  640  secured on an external surface of a chest via a patch or even implanted subcutaneously. Sensor  2640  communicates wirelessly with power element  2622  and/or control portion  1700 . In some embodiments, belt  2630  or the other sensor  2640  includes an accelerometer or piezoelectric transducer for detecting body motion/position and/or many other types of physiologic information, with such sensed information also being used within system  2600 . 
     In some examples, system  2600  comprises a charging station  2650  to supply power to a power element (e.g. at least  140  in  FIG. 6A, 152  in  FIG. 6B, 110  in  FIGS. 5, 8 )  6 B in microstimulator  2635 . In some examples, system  2600  transmits the power to the implantable microstimulator  2635  via coils  2620 . It is also understood that in some examples, coils  2620  also may be used to transmit and/or receive control information relative to the microstimulator  2635 . In some examples, coils  2620  may be used to transmit and/or receive sensor information relative to the microstimulator  2635 . 
     In some examples, a power element (e.g.  110  in  FIGS. 5, 6A, 8 ) associated with the microstimulator  2635  comprises an implantable, re-chargeable first portion and an external second portion to selectively re-charge the first portion. The second portion is external to the patient. The first portion may comprise a power element contained within or otherwise coupled to implantable microstimulator  2635 . In some examples, the second portion is implemented via at least some of the features and attributes of charging station  2650  whether alone or in association with patient support  2604 ,  2606 , coils  2620 , etc. 
     In some examples, charging station  2650  comprises an inductive charging arrangement  2652  by which power is transmitted to rechargeable power element in microstimulator  2635  via coils  2620  according to a general induction element(s)  2654  or a highly resonant induction element(s)  2656 . 
     In some examples, charging station  2650  comprises a radiofrequency (RF) charging arrangement  2660  by which power is transmitted to rechargeable power element in microstimulator  2635  according to an RF rectification element(s)  2662  or a low power microwave element(s)  2664 . 
     As previously noted, in some examples the charging station  2650  includes a sensor information transmission function  2670  by which sensed information may be transmitted to the microstimulator  2635 . In some examples, the sensor information transmission function  2670  transmits the sensed information as part of a re-charging signal transmitted in association with the re-charging functions of charging station  2650 . 
     In some examples, at least some aspects of the charging station  2650  may provide one example implementation of the external power element  170  in the arrangement of  FIG. 6B . 
     In some examples, it will be understood that at least a portion and/or at least some functions of the charging station may be implemented via a handheld device. 
       FIG. 7  is a block diagram schematically representing communication element  112 , according to one example of the present disclosure. As represented in  FIG. 7 , in some examples communication element  112  may be implemented via at least one of various communication modalities such as an external communication modality  190 , an inductive communication modality  192 , and/or a radiofrequency communication modality  194 . It will be understood that in some examples these various modalities are not mutually exclusive. 
     In some examples, communication element  112  is implemented via an external communication modality  190  in which a device external to the patient communicates information to, and receives information from, the therapy device  100 . In some examples, this modality enables the external device to configure various therapy parameters by programming and/or adjusting parameters of the therapy manager  122  and/or control portion  120  of therapy device  100 . 
     In some examples, the inductive communication modality  192  performs communication via a set of coils separate from, and different from, any coils implemented as part of power element  110  (e.g.  FIGS. 5-6 ). In some examples, the inductive communication modality  192  performs communication via at least some coils which are common with at least some coils implemented as part of one of the modalities of power element  110  ( FIGS. 5-6 ). 
     In some examples, the radiofrequency modality  194  shown in  FIG. 7  enables reducing power requirements during communication via an asymmetric protocol in which transmissions from the implanted therapy device  100  to the external device uses a lower data rate. 
     In some examples, the radiofrequency modality  194  enables reduced power usage via wakeup rate optimization. In some examples, an increase wakeup rate is used to decrease communication latency. In some examples, application of an external magnet is used to increase wakeup rate. In some examples, prediction of onset of sleep is used to increase wakeup rate. In some examples, these arrangements are employed via an external power source with a radiofrequency (RF) link. 
     Accordingly, it will be understood that in some examples, at least some of these aspects of communication element  112  enhance and/or may define at least a portion of power element  110 . Similarly, in some examples and as noted elsewhere throughout at least some examples of the present disclosure, power element  110  may define at least a portion of communication element  112 . 
       FIG. 8  is a block diagram schematically representing components of a microstimulation therapy device  200 , according to one example of the present disclosure. As shown in  FIG. 8 , microstimulation therapy device  200  includes power element  110 , stimulation circuitry  112 , communication element  114 , and a control portion  120  having therapy manager  122 . In some examples, microstimulation therapy device  200  includes at least some of substantially the same features and attributes as microstimulation therapy device  100  as previously described in association with at least  FIG. 5 , except for microstimulation therapy device  200  further including a sensing function  205 . In some examples, sensing function  205  receives sensed information for further use by therapy manager  122  and/or control portion  120  to evaluate and/or perform therapy. As such, in some examples, sensing function  205  provides feedback to enable operation of therapy device  200  in a closed loop system. One such closed loop function  1630  is described later in association with at least  FIG. 24 , while other aspects associated with closed loop functioning are described throughout at least some examples of the present disclosure. 
     In some examples, sensing function  205  is implemented via a sensor ( 210  in  FIG. 9A ;  250  in  FIG. 9B ;  300  in  FIG. 10 ) forming part of microstimulation therapy device  200 . However, in some examples, a sensor ( 210  in  FIG. 9A ;  250  in  FIG. 9B ;  300  in  FIG. 10 ) may be separate from, and independent of a therapy device ( FIG. 8 ), according to one example of the present disclosure. In some examples, while separate from and independent of therapy device  200 , a sensor ( 210  in  FIG. 9A ;  250  in  FIG. 9B ;  300  in  FIG. 10 ) is dedicated to providing sensed information to therapy device  200 . 
     In some examples, a sensor ( 210  in  FIG. 9A ;  250  in  FIG. 9B ;  300  in  FIG. 10 ) is not dedicated to providing sensed information to microstimulation therapy device  200 . As such sensor  210 / 250 / 300  may be part of a system which is independent of therapy device  200  or sensor  210 / 250 / 300  may be a standalone sensor not associated with any other system or device. For instance, in some examples, a sensor ( 210 ,  250 , and  300 ) comprises a portion of a cardiac device. 
     In either case, further details regarding at least some examples of such sensors are described later in association with at least  FIGS. 9-10 . 
     With further reference to  FIG. 8 , the sensing function  205  receives and tracks signals from various physiologic sensors in order to determine respiratory information, sleep quality information, sleep disordered breathing (SDB) information, cardiac information, etc. This information may be received from either a single sensor or any multiple of sensors, or combination of various physiologic sensors which may provide a more reliable and accurate signal. In some examples, sensing function  205  receives this information from sensor(s)  210 ,  250   300 , as later described in association with at least  FIGS. 9-10 . 
       FIG. 9A  is a block diagram schematically representing a sensor  210 , according to one example of the present disclosure. In some examples, sensor  210  corresponds to a sensor external to microstimulation therapy device  200  which cooperates with sensing function  205  of microstimulation therapy device  200  in  FIG. 8  and/or corresponds to a sensor incorporated within the microstimulation therapy device  200  which at least partially implements the sensing function  205  in  FIG. 8 , as previously described or later described in the examples of the present disclosure. 
     In some examples, sensor  210  is an implantable sensor implanted within a patient&#39;s body separately from microstimulation therapy device  200 , as represented by  226  in  FIG. 9A . In some examples, an implantable sensor forms part of another component implanted within the patient&#39;s body, such as on-board the microstimulation therapy device  200  in  FIG. 8 , and as such is represented by  220  in  FIG. 9 . In such examples, the on-board sensor  220  may form part of the housing of the microstimulation therapy device  200  and therefore may be exposed to the internal environment of the patient. On the other hand, in such examples, the on-board sensor  220  may be housed internally within the microstimulation therapy device  200  and be isolated from the internal environment of the patient. While a fuller discussion of sensor types  300  is reserved until a later discussion of  FIG. 10 , it will be noted that an accelerometer (e.g.  306  in  FIG. 10 ) is one example of an implantable sensor, which may be internally housed within a microstimulation device as an on-board sensor  220 . 
     In some examples, implantable sensor  226  may comprise stand-alone implantable sensors distributed throughout the patient&#39;s body and which communicate wirelessly to a microstimulation therapy device  200  or to an external device that integrates the sensed data. For instance, one stand-alone implantable sensor may comprise an oxygen sensor. 
     With further reference to  FIG. 9A , in some examples sensor  210  comprises an external sensor  222  that remains external to a patient&#39;s body. The external sensor  222  may be a wearable sensor  230  or an environment sensor  232 , which is part of the patient&#39;s environment and which senses information from the patient and/or regarding the environment in which the patient is present. In some examples, a wearable sensor  230  may be used to sense heart rate variability such that the wearable sensor  230  need not be part of an implantable microstimulation therapy device  200  or external therapy device. Rather, one may simply add the wearable sensor  230  at a later time to monitor parameters associated with a therapy performed to alleviate sleep disordered breathing. 
     In some examples, a wearable sensor  230  may comprise a commercially available wearable sensor which includes an array of sensors for measuring heart rate (e.g. LED, optical sensor), sleep quality/motion (e.g.  3 D accelerometer), ambient light, etc. In some instances, the wearable sensor  230  includes a touchscreen display to facilitate tracking and monitoring of the sensed conditions. In some instances, the wearable sensor  230  includes a wireless communication tool for communicating with a dongle, mobile device, etc. via a wireless communication protocol (e.g. Bluetooth, NFC, etc.). In one instance, such a wearable sensor  230  is available from FitBit, Inc. of San Francisco, Calif. In some examples, such a system may include a single sensor or array of sensors which provide respiratory information, cardiac information, sleep quality information, sleep disordered breathing (SDB) information, and/or other information. In some examples, this information may be coordinated with information sensed or determined via the microstimulation therapy device  200 . In some examples, the therapy manager  122  may include a sensor profile manager to coordinate information sensed via the wearable sensor  230 . 
     In some examples, information from external sensors  222  can be coordinated with information from implantable sensors  220 ,  226 . 
     In some examples, external sensor  222  comprises an integrated external sensing system for tracking sleep quality, heart rate, breathing rhythm, movement, sleep stages, snoring, and sleep environment (e.g., noise level and light). One example system comprises the Beddit® system available from www.beddit.com. In some examples, such a system may provide respiratory information, cardiac information, sleep quality information, sleep disordered breathing (SDB) information, and/or other information. In some examples, this information may be coordinated with information sensed or determined via the microstimulation therapy device  200 . In some examples, the therapy manager  122  may include a sensor profile manager to coordinate information sensed via the external sensor  220 . 
     In some examples, an external sensor(s)  222  may comprise clinically available diagnostic equipment such as ECG sensors, a blood pressure cuff, oxygen sensor, etc. 
     In some instances, the environment sensor  232  shown in  FIG. 9  comprises a non-contact sensor  234 , which does not make contact with the patient. In one instance, non-contact sensor  234  comprises at least some of substantially the same features and attributes as the non-contact sensor paradigm described in Heneghan et al. U.S. Pat. No. 5,562,526, which may be used by microstimulator device  200  to provide respiratory information, cardiac information, sleep quality information, sleep disordered breathing (SDB) information, and/or other information. In one instance, one such system is available from Resmed Corporation of San Diego, Calif. 
     In some instances, the non-contact sensor  234  incorporates or cooperates with one of the sensor modalities described in association with at least  FIG. 10 , such as but not limited to, a radiofrequency sensor  308 . The signal produced by sensing via the radiofrequency sensor  308  may be processed to detect patient motion/activity, breathing (e.g. respiratory rate), heart rate, and/or a sleep stage of the patient. 
     In some examples, sensor  210  may comprise a sensor providing a combination sensor or combination sensor array, which combines at least some aspects of the various implantable sensors and external sensors. 
     In some examples, sensor  210  comprises an electrode associated with the microstimulation therapy device ( 100  in  FIG. 5 ;  200  in  FIG. 8 ) and as later further described in association with at least  FIGS. 14A-18B, 19A-20B, 21A-23B , in which a stimulation signal generated via the stimulation circuitry of one of the microstimulation therapy devices  100 ,  200  is applied to a target nerve via such an electrode. In some instances, such electrodes may sometimes also be used as a sensor, such as but not limited to, sensing a bio-impedance of the patient to obtain respiratory information, cardiac information, sleep quality information, sleep disordered breathing (SDB) information, etc. 
     In some examples, sensor  210  includes and/or utilizes inductive coupling to effectuate communication between sensor  210  and at least some components (e.g. communication element  114  in  FIG. 8 ) of the microstimulation therapy device  200  ( FIG. 8 ). 
       FIG. 9B  is a block diagram schematically representing a sensor type  250 , according to one example of the present disclosure. In some examples, at least some of the sensing arrangements  252 - 272  in  FIG. 9B  may be implemented via at least some of the sensor types  220 - 234  in  FIG. 9A  and/or sensor types  302 - 322  in  FIG. 10 . As shown in  FIG. 9B , in some examples one sensor type comprises an airway position sensing arrangement  252  provide sensed information regarding an airway position while airflow obstruction sensing arrangement  254  provides sensed information regarding airflow obstructions. In some examples, airflow sensing arrangement  256  provides sensed general airflow information. As further shown in  FIG. 9B , in some examples respiratory sensing arrangement  258  provides general and/or specific sensed respiratory information while in some examples, sleep disordered breathing (SDB) sensing arrangement  260  provides sensed information regarding at least sleep disordered breathing (SDB) events, such as but not limited to apneas  262  and/or hypopneas  264 . In some examples, body position sensing arrangement  270  provides sensed information related to at least body position, which may involve posture, motion, activity, body orientation, etc. In some examples, implant temperature sensing arrangement  272  provides sensed information regarding at least a temperature of an implant. In some examples, such sensed implant temperature information facilitates recharging modalities and functionalities. 
     In some examples, sensed information may be obtained via a combination of at least some of the various sensing arrangements  252 - 272  in  FIG. 9B . 
       FIG. 10  is a block diagram schematically representing a sensor type  300  according to one example of the present disclosure. In some examples, sensor type  300  corresponds to a sensor (e.g.,  210  in  FIG. 9 ) and/or a sensing function ( 205  in  FIG. 8 ), as previously described or later described in the examples of the present disclosure. 
     As shown in  FIG. 10 , sensor type  300  comprises various types of sensor modalities  302 - 320 , any one of which may be used for determining, obtaining, and/or monitoring respiratory information, cardiac information, sleep quality information, sleep disordered breathing-related information, and/or other information related to providing patient therapy. 
     As shown in  FIG. 10 , in some examples sensor type  300  comprises the modalities of pressure  302 , impedance  304 , accelerometer  306 , airflow  307 , radiofrequency (RF)  308 , optical  310 , electromyography (EMG)  312 , electrocardiography (ECG)  314 , ultrasonic  316 , acoustic  318 , image  319 , and/or other  320 . In some examples, sensor type  300  comprises a combination  322  of at least some of the various sensor modalities  302 - 320 . 
     It will be understood that, depending upon the attribute being sensed, in some instances a given sensor modality identified within  FIG. 10  may include multiple sensing components while in some instances, a given sensor modality may include a single sensing component. Moreover, in some instances, a given sensor modality identified within  FIG. 10  may include power circuitry, monitoring circuitry, and/or communication circuitry. However, in some instances a given sensor modality in  FIG. 10  may omit some power, monitoring, and/or communication circuitry but may cooperate with such monitoring or communication circuitry located elsewhere. 
     In some examples, a pressure sensor  302  may sense pressure associated with respiration and can be implemented as an external sensor  222  ( FIG. 9 ) and/or an implantable sensor  226  ( FIG. 9 ). In some instances, such pressures may include an extrapleural pressure, intrapleural pressures, etc. For example, one pressure sensor  302  may comprise an implantable respiratory sensor, such as that disclosed in Ni et al. U.S. Patent Publication 2011-0152706, published on Jun. 23, 2011, titled METHOD AND APPARATUS FOR SENSING RESPIRATORY PRESSURE IN AN IMPLANTABLE STIMULATION SYSTEM. 
     In some instances, pressure sensor  302  may include a respiratory pressure belt worn about the patient&#39;s body. 
     In some examples, a pressure sensor  302  can sense sound and/or pressure waves at a different frequency than occur for respiration (e.g. inspiration, exhalation, etc.). In some instances, this data can be used to track cardiac parameters of patients via a respiratory rate and/or a heart rate. In some instances, such data can be used to approximate electrocardiogram information, such as a QRS complex. In some instances, the detected heart rate is used to identify a relative degree of organized heart rate variability, in which organized heart rate variability may enable detecting apneas or other sleep disordered breathing events, which may enable evaluating efficacy of sleep disordered breathing. 
     In some examples, pressure sensor  302  comprises piezoelectric element(s) and may be used to detect sleep disordered breathing (SDB) events (e.g. apnea-hypopnea events), to detect onset of inspiration, and/or detection of an inspiratory rate, etc. 
     As shown in  FIG. 10 , in some examples one sensor modality includes air flow sensor  307 , which can be used to sense respiratory information, sleep disordered breathing-related information, sleep quality information, etc. In some instances, air flow sensor  307  detects a rate or volume of upper respiratory air flow. 
     As shown in  FIG. 10 , in some examples one sensor modality includes impedance sensor  304 . In some examples, impedance sensor  304  may be implemented in some examples via various sensors distributed about the upper body for measuring a bio-impedance signal, whether the sensors are internal and/or external. In some examples, the impedance sensor  304  senses an impedance indicative of an upper airway collapse. 
     In some instances, the sensors are positioned about a chest region to measure a trans-thoracic bio-impedance to produce at least a respiratory waveform. 
     In some instances, at least one sensor involved in measuring bio-impedance can form part of a pulse generator, whether implantable or external. In some instances, at least one sensor involved in measuring bio-impedance can form part of a stimulation element and/or stimulation circuitry. In some instances, at least one sensor forms part of a lead extending between a pulse generator and a stimulation element. 
     In some examples, impedance sensor  304  is implemented via a pair of elements on opposite sides of an upper airway. Some example implementations of such an arrangement are further described later in association with at least  FIG. 11 . 
     In some examples, impedance sensor  304  may take the form of electrical components not used in a microstimulation therapy device  200 . For instance, some patients may already have a cardiac therapy device (e.g. pacemaker, defibrillator, etc.) implanted within their bodies, and therefore have some cardiac leads implanted within their body. Accordingly, the cardiac leads may function together or in cooperation with other resistive/electrical elements to provide impedance sensing. 
     In some examples, whether internal and/or external, impedance sensor(s)  304  may be used to sense an electrocardiogram (ECG) signal. 
     In some examples, impedance sensor  304  is used to detect sleep disordered breathing (SDB) events (e.g. apnea-hypopnea events), to detect onset of inspiration, and/or detection of an inspiratory rate, etc. 
     As shown in  FIG. 10 , in some examples one sensor modality includes an accelerometer  306 . In some instances, accelerometer  306  is generally incorporated within or associated with microstimulation therapy device  200 . For instance, in some examples of a therapy device  200 , a housing (e.g. can) contains numerous components such as control circuitry, stimulation, and also may contain an accelerometer  306  within the housing. However, in some examples, the accelerometer  306  may be separate from, and independent of, the microstimulation therapy device  200 . In some examples, accelerometer  306  can enable sensing body position, body posture, and/or body activity/motion regarding the patient, which may be indicative of behaviors from which sleep quality information or sleep disordered breathing (SDB) information may be determined. In some instances, body posture/position is sensed via at least the accelerometer  306  and is used to detect start of sleep. 
     For instance, as further addressed in association with at least  FIG. 24 , sleep position (e.g. left side, right side, supine, etc.) may be used to determine the effectiveness of SDB therapy according to sleep position, and in some instances, the SDB therapy may be automatically adjusted based on the orientation (i.e. sleep position) of the patient. In some instances, this information regarding sleep position may be communicated to the patient during a sleep period in order to induce the patient to change their sleep position into one more conducive to efficacious therapy. In some examples, the communication may occur by an audible or vibratory alarm implemented via wireless communication to a patient remote or via direct muscle stimulation via wireless communication to a wearable muscle stimulation device. 
     Among other uses, the information obtained via the accelerometer  306  may be employed by a clinician to adjust stimulation therapy and/or employed by a therapy device (and/or manager) to automatically adjust stimulation therapy to cause a decrease in the moving average of the sleep apnea index (e.g. AHI). Moreover, as previously mentioned this information may be used to communicate to the patient via audio or non-audio techniques to change their sleep position to a position (e.g. left side) more amenable to regular respiration. 
     In some examples, accelerometer  306  enables acoustic detection of cardiac information, such as heart rate via motion of tissue in the head/neck region, similar to ballistocardiogram and/or seismocardiogram techniques. In some examples, measuring the heart rate includes sensing heart rate variability. In some examples, accelerometer  306  can sense respiratory information, such as but not limited to, a respiratory rate. In some examples, whether sensed via an accelerometer  306  alone or in conjunction with other sensors, one can track cardiac information and respiratory information simultaneously by exploiting the behavior of the cardiac signal in which a cardiac waveform can vary with respiration. 
     In some examples, accelerometer  306  enables detection of sleep/awake via the sensing of motion, position, posture and/or activity of the patient, along with other parameters determinable via the accelerometer  406 . In some instance, this information may be used to implement automatic control of stimulation therapy to enhance therapeutic efficacy and/or reduce power requirements. 
     In some examples, accelerometer  306  is used to detect sleep disordered breathing (SDB) events (e.g. apnea-hypopnea events), to detect onset of inspiration, and/or detection of an inspiratory rate, etc. 
     In some examples, the accelerometer  306  comprises an external sensor  222  ( FIG. 9 ). In some instances, when embodied as an external sensor, the accelerometer  306  may comprise a wearable sensor, such as an accelerometer incorporated into a band or belt worn about a portion of the body (e.g. wrist, chest, arm, leg, torso, etc.). 
     In some examples, the accelerometer  306  may be used to detect sleep disordered breathing events during the sleep period and may be used continuously to detect arrhythmias. 
     In some examples, radiofrequency sensor  308  shown in  FIG. 10  enables non-contact sensing of various physiologic parameters and information, such as but not limited to respiratory information, cardiac information, motion/activity, and/or sleep quality, such as previously described regarding non-contact sensor  234  in association with at least  FIG. 9 . In some examples, radiofrequency sensor  308  enables non-contact sensing of other physiologic information. In some examples, radio-frequency (RF) sensor  308  determines chest motion based on Doppler principles. The sensor  308  can be located anywhere within the vicinity of the patient, such as various locations within the room (e.g. bedroom) in which the patient is sleeping. In some examples, the sensor  308  is coupled to a monitoring device to enable data transmission relative to other components of a microstimulation therapy device  200  and storage in such other components. 
     In some examples, one sensor modality may comprise an optical sensor  310  as shown in  FIG. 10 . In some instances, optical sensor  310  may be an implantable sensor  226  and/or external sensor  222  ( FIG. 9 ). For instance, one implementation of an optical sensor  310  comprises an external optical sensor for sensing heart rate and/or oxygen saturation via pulse oximetry. In some instances, the optical sensor  310  enables measuring oxygen desaturation index (ODI). In some examples, the optical sensor  310  comprises an external sensor removably couplable on the finger of the patient. 
     In some examples, optical sensor  310  can be used to measure ambient light in the patient&#39;s sleep environment, thereby enabling an evaluation of the effectiveness of the patient&#39;s sleep hygiene and/or sleeping patterns. 
     As shown in  FIG. 10 , in some examples one sensor modality comprises EMG sensor  312 , which records and evaluates electrical activity produced by muscles, whether the muscles are activated electrically or neurologically. In some instances, the EMG sensor  312  is used to sense respiratory information, such as but not limited to, respiratory rate, apnea events, hypopnea events, whether the apnea is obstructive or central in origin, etc. For instance, central apneas may show no respiratory EMG effort. 
     In some instances, the EMG sensor  312  may comprise a surface EMG sensor while, in some instances, the EMG sensor  312  may comprise an intramuscular sensor. In some instances, at least a portion of the EMG sensor  312  is implantable within the patient&#39;s body and therefore remains available for performing electromyography on a long term basis. 
     In some examples, one sensor modality may comprise ECG sensor  314  which produces an electrocardiogram (ECG) signal. In some instances, the ECG sensor  314  comprises a plurality of electrodes distributable about a chest region of the patient and from which the ECG signal is obtainable. In some instances, a dedicated ECG sensor(s)  314  is not employed, but other sensors such as an array of bio-impedance sensors  304  are employed to obtain an ECG signal. In some instances, a dedicated ECG sensor(s) is not employed but ECG information is derived from a respiratory waveform, which may be obtained via any one or several of the sensor modalities in sensor type  300  in  FIG. 10 . In some examples, ECG sensor  314  is embodied as an accelerometer  306  as previously described in association with  FIGS. 9-10 . 
     In some examples, an ECG signal obtained via ECG sensor  314  may be combined with respiratory sensing (via pressure sensor  302  or impedance sensor  304 ) to determine minute ventilation, as well as a rate and phase of respiration. In some examples, the ECG sensor  314  may be exploited to obtain respiratory information (e.g. at least  1660  in  FIG. 24 ). In some examples, as noted elsewhere, ECG sensor  314  may be implemented, at least in part, as an accelerometer  306  ( FIG. 10 ). 
     In some examples, ECG sensor  314  is used to detect sleep disordered breathing (SDB) events (e.g. apnea-hypopnea events), to detect onset of inspiration, and/or detection of an inspiratory rate, etc. 
     As shown in  FIG. 10 , in some examples one sensor modality includes an ultrasonic sensor  316 . In some instances, ultrasonic sensor  316  is locatable in close proximity to an opening (e.g. nose, mouth) of the patient&#39;s upper airway and via ultrasonic signal detection and processing, may sense exhaled air to enable determining respiratory information, sleep quality information, sleep disordered breathing information, etc. In some instances, ultrasonic sensor  316  may comprise at least some of substantially the same features and attributes as described in association with at least Arlotto et al. PCT Published Patent Application 2015-014915 published on Feb. 5, 2015. 
     In some examples, acoustic sensor  318  comprises piezoelectric element(s), which sense acoustic vibration. In some implementations, such acoustic vibratory sensing may be used to detect sleep disordered breathing (SDB) events (e.g. apnea-hypopnea events), to detect onset of inspiration, and/or detection of an inspiratory rate, etc. 
     In some examples, acoustic sensor  318  detects snoring information, which may be used in detection, evaluation, and/or modification of sleep-related information and/or therapy parameters. 
     In some examples, one of the sensor types  300  (and/or sensors  200 ) or a combination of such sensors senses local or gross motion, such as snoring, inspiration/expiration, etc., which may be indicative to sleep quality, sleep disordered breathing events, general respiratory information, etc. 
     In some examples, information sensed via sensor  210  in  FIG. 9  and/or via sensor types  300  in  FIG. 10 , such as but not limited to motion information, can be used in a training mode of the microstimulation therapy device ( 200  in  FIG. 8 ) to correlate the patient&#39;s respiration with the sensed motion. 
     In some examples, several sensor modalities of the sensory types  300  are combined, as represented via combination identifier  322 . 
       FIG. 11  is a diagram  350  schematically representing an impedance sensor array  360  implanted in a head/neck region  352 , according to one example of the present disclosure. In some examples, impedance sensor array  360  comprises at least some of substantially the same features and attributes as impedance sensor  304  ( FIG. 10 ). As shown in  FIG. 11 , sensor array  360  includes a first sensing element  361  and a second sensing element  362 . In some examples, both sensing elements  361 ,  362  comprise some form of electrically conductive element such that a bio-impedance can be measured between the respective sensing elements  361 ,  362  positioned on opposite sides of an upper airway in the head/neck region  352 . In some examples, the measured bio-impedance may indicate a relative degree of upper airway patency or collapse. In some examples, one or both of sensing elements  361 ,  362  may comprise tines to prevent migration of the respective sensing elements  361 ,  362 . 
     In some examples, the sensing element  361  comprises at least a conductive element of a microstimulation therapy device, such as therapy device  200  in  FIG. 8 . Accordingly, the therapy device  200  itself may form part of the impedance sensor array  360 . In this arrangement, in some examples, the other sensing element  362  is inserted at the opposite side of the head/neck region  352  via use of a tunneling tool. 
     In some examples, the sensing element  361  comprises a housing of a first microstimulation therapy device, such as therapy device  200  in  FIG. 8  and the other sensing element  362  comprises a housing of a second microstimulation therapy device, which is separate from, and independent of the first microstimulation therapy device  200 . In some implementations, these sensing elements  361 ,  362  function as an impedance sensor  304 . In some implementations, the two sensing elements  361 ,  362  (implemented via two independent microstimulation therapy devices  200 ) are placed on opposite sides of the throat of the patient and communicate wirelessly with each other to sense inhalation and exhalation. 
       FIG. 12  is a block diagram schematically representing mechanical coupling arrangements  400  for securing at least a microstimulation therapy device within a subcutaneous environment, according to one example of the present disclosure. As shown in  FIG. 12 , one coupling arrangement includes a bony structure coupling arrangement  402  in which at least a portion of the housing of the microstimulation therapy device (e.g.  100  in  FIG. 5, 200  in  FIG. 8 ) is secured via a fixation mechanism relative to a bony structure accessible within a subcutaneous environment. In this arrangement, a stimulation element such as a contact electrode is located at a target nerve while the housing of the microstimulation therapy device (e.g.  100 ,  200 ) is spaced apart from the target nerve stimulation site. In some instances, the housing may be considered to be located remotely from the target nerve site. 
     For instance, in some examples, the bony structure may comprise the mandible. In some instances, the housing of the therapy device  100 ,  200  is fixed via screws or other fastening mechanism(s). In some instances, fixation occurs at an inferior portion of the mandible and may potentially involve bone removal to facilitate the fixation. In some instances, fixation occurs at inner portion of the mandible but without involving bone removal. 
     In some examples, the housing of the microstimulation therapy device  100 ,  200  can be placed behind the ear, or elsewhere on the cranium. In such arrangements, fixation may occur via a screw associated with the housing of the therapy device  100 ,  200  and/or via other fixation mechanisms. 
     As shown in  FIG. 12 , one coupling arrangement includes a non-nerve, non-bony structure coupling arrangement  404  in which at least a portion of the housing of the microstimulation therapy device  100 ,  200  is secured via a fixation mechanism relative to a non-bony structure accessible within a subcutaneous environment. In this arrangement, a stimulation element such as a contact electrode is located at a target nerve while the housing of the microstimulation therapy device (e.g.  100 ,  200 ) is spaced apart from the target nerve stimulation site. In some instances, the housing is located remotely from the target nerve stimulation site. In some instances, the housing of the microstimulation therapy device (e.g.  100 ,  200 ) can be placed superior to the mylohyoid, which in some instances, further involves the use of tines for mechanical fixation to prevent migration. 
     In some examples, a microstimulation therapy device  100 ,  200  secured via arrangements  402  or  404  can communicate with either an implanted generator (e.g. pectoral) or external generator module which can contain a power source accessible by the implanted microstimulation therapy device. 
     In some examples, a microstimulation therapy device  100 ,  200  secured via arrangements  402  or  404  can communicate with a sensor  210 ,  300 , whether implanted or external. In some implementations, the sensor  210 ,  300  can be passively powered or can have an internal primary/rechargeable power source. 
     As shown in  FIG. 12 , one coupling arrangement includes a nerve structure coupling arrangement  410  in which at least a portion of the housing of the microstimulation therapy device  100 ,  200  is secured via a fixation mechanism relative to a nerve within a subcutaneous environment. In this arrangement, at least a housing of the microstimulation therapy device  100 ,  200  is located directly at the target nerve stimulation site. In some examples in which a stimulation element (e.g. contact electrode) extends from the housing of the microstimulation therapy device, both the microstimulation therapy device  100 ,  200  and stimulation element may be located in close proximity to a target stimulation site, as later shown and described in association with at least  FIGS. 14A-18D . 
       FIG. 13  is a block diagram schematically representing electrical coupling arrangements  422 - 434  for a microstimulation therapy device, according to one example of the present disclosure. In general terms, the various electrical coupling arrangements  422 - 434  provide a means by which stimulation pulses from the microstimulation therapy device  100 ,  200  are coupled to a target nerve. 
     As shown in  FIG. 13 , one coupling arrangement includes a direct coupling arrangement  422  in which a housing of the microstimulation therapy device  100 ,  200  includes at least one exposed electrically conductive element that directly contacts the target nerve. In one aspect, one such arrangement is further described later in association with at least  FIGS. 16A-16C . In some examples, an array of such conductive elements is present on an outer surface of the housing of the microstimulation therapy device. In one aspect, one such arrangement is further described later in association with at least  FIGS. 14A-14C . 
     As shown in  FIG. 13 , one coupling arrangement includes an indirect coupling arrangement  424  in which an outer surface of the housing of the microstimulation therapy device  100 ,  200  does not include any exposed electrically conductive elements. In one aspect, one such arrangement is further described later in association with at least  FIGS. 15A-15C  in which an electrode array extends outwardly from the housing of the microstimulation therapy device to establish contact with the target nerve. 
     As shown in  FIG. 13 , one coupling arrangement includes an axial array coupling arrangement  430  in which an array of electrically conductive elements is arranged to be axially aligned with a length of the target nerve. In some examples, the axial array of conductive elements is located on an outer surface of a housing of the microstimulation therapy device. In one aspect, one such arrangement is further described later in association with at least  FIGS. 14A-14C . In some examples, the axial array of conductive elements is not located on an outer surface of a housing of the microstimulation therapy device, but forms a structure extending outwardly from the housing of the therapy device. In one aspect, one such arrangement is further described later in association with at least  FIGS. 17A-17C . 
     As shown in  FIG. 13 , one coupling arrangement includes a radial array coupling arrangement  432  in which an array of electrically conductive elements is arranged in an arcuate pattern to be spaced apart and extend about a circumference of a target nerve. In one aspect, the electrically conductive elements may be considered to be radially arranged to the extent that each electrically conductive element is positioned at the end of a virtual radius from a center point (e.g. a center of the cross-section of the nerve), with the ends of the virtual radii spaced apart from each other about a circumference of the nerve. 
     In some examples, the radial array of conductive elements is deployed as part of a structure extending outwardly from the housing of the therapy device, such as at least one flange of a pair of flanges used to mechanically couple the therapy device relative to the target nerve. In one aspect, one such arrangement is further described later in association with at least  FIGS. 15A-15B . 
     As shown in  FIG. 13 , one coupling arrangement includes a grid array coupling arrangement  434  in which an array of electrically conductive elements is arranged in a grid. In some examples, the grid array of conductive elements forms a structure extending outwardly from the housing of the therapy device, such as a paddle extending about a portion of the target nerve. In one aspect, one such arrangement is further described later in association with at least  FIGS. 16A-16B . However, in some examples, the grid array of conductive elements is located on an outer surface of the housing of the microstimulation therapy device. In one aspect, one such arrangement is further described later in association with at least  FIGS. 18A-18B . 
     It will be understood that at least some of the examples of mechanical coupling arrangements ( FIG. 12 ) may be combined with at least some examples of electrical coupling arrangements ( FIG. 13 ). Moreover, in some examples, more than one electrical coupling arrangement may be implemented and in some examples, more than one mechanical coupling arrangement may be implemented. In other words, in some examples, at least some of the various mechanical are not mutually exclusive and at least some of the various electrical coupling arrangements are not mutually exclusive. 
       FIG. 14A  is a diagram  500  schematically representing a microstimulation therapy device  520  implanted relative to a nerve  512  of array  510  of nerves within a subcutaneous, extravascular environment  502 , according to one example of the present disclosure. In some examples the microstimulation therapy device  520  comprises at least some of substantially the same features and attributes as the previously described microstimulation therapy devices  100 ,  200 . As shown in  FIG. 14A , therapy device  520  includes a housing  522  extending between opposite ends  523 A,  523 B with housing  522  having a generally electrically non-conductive outer surface  524 . Housing  522  contains a stimulator ( 100 ,  200  in  FIGS. 5, 8 ) and may sometimes be referred to as defining or including a body of the therapy device  520 . 
     An array  530  of three ring electrodes  532  are arranged in an axially spaced apart manner along a length of the housing  522 . In some examples, a fewer number or greater number of ring electrodes  532  may be used. In some examples, the electrodes  532  may be implemented as partial ring electrodes  532 , and thus not extend about a complete circumference of the housing  522  provided that at least a portion of the respective partial ring electrodes  522  can establish contact against the nerve  512 . 
     In some examples, the non-conductive area of the housing  522  defines a first portion. Each respective electrode  532  defines one of three second portions, each of which is surrounded by the non-conductive first portion. 
     As further shown in  FIG. 14B , a pair of flanges  540 A,  540 B extend outwardly from the housing  522  of therapy device  520  and are biased to encircle and releasably engage nerve  512  to mechanically (and directly) secure the housing  522  relative to, and in contact against, nerve  512  such that electrodes  532  become directly electrically coupled relative to the nerve  512  (e.g. nerve bundle). In some instances, the flanges  540 A,  540 B may be sometimes be referred to as wrapping around or about the nerve  512 . In some examples, each flange  540 A,  540 B may sometimes be referred to as an at least partially flexible element. In some examples, the flanges  540 A,  540 B are made from a polymer material, such as but not limited to a polyurethane material or one of several biocompatible materials, alone or in combination. In at least some examples, this arrangement enables application of stimulation therapy for treating sleep disordered breathing (SDB). 
     In some examples, the housing  522  of therapy device  520  has a length at least two times a diameter or width of the housing  522  with the elongate configuration enhancing stability of the housing  522  when secured against nerve  512 . 
     In some examples, the body  522  has a volume less than about cubic centimeters. 
     With general reference to at least  FIGS. 14A-14B , in some examples, housing  522  of microstimulation therapy device  520  has opposite ends  523 A,  523 B formed of electrically non-conductive material, and therefore in some examples, no electrical transmission of stimulation pulse occurs through the ends  523 A,  523 B of housing  522 . 
     With further general reference to at least  FIGS. 14A-14B , in some examples, the housing  522  of microstimulation therapy device  520  has opposite ends  523 A,  523 B devoid of fixation elements. In other words, in such examples the housing  522  lacks any mechanical element (such as but not limited to a screw) protruding axially from end of housing  522  or otherwise configured at end(s) of housing  522  for fixating solely the end of the housing  522  relative to a bony structure. 
     With further general reference to  FIGS. 14A-14B , in some examples, housing  522  of microstimulation therapy device  520  is not invasively fixed relative to the tissue (e.g. nerve  512 ) to which electrical stimulation is to be applied and/or is located remotely from the muscle targeted for contraction. Accordingly, in some instances, the housing  522  may sometimes be referred to as being non-nerve-invasively secured or being non-invasively secured relative to the nerve to be electrically stimulated. 
     In sharp contrast to at least some examples of the present disclosure, some commercially available implantable stimulators are attached to the to-be-stimulated tissue (e.g. cardiac wall) via a screw which is invasively implanted within the to-be-stimulated tissue (e.g. cardiac wall), where a to-be-stimulated tissue is a muscle targeted for contraction. In such examples, the fixation mechanism penetrates the tissue to which electrical stimulation is applied. 
     In sharp contrast to some commercially available injectable stimulators, the housing  522  of therapy device  520  (of at least some examples of the present disclosure) is secured relative to the tissue (e.g. nerve) to be stimulated, thereby minimizing and/or avoiding migration while enhancing patient comfort. 
     With further general reference to at least  FIGS. 14A-14B , in some examples, a contact interface between housing  522  of the microstimulation therapy device  520  and nerve  512  does not define a primary securing interface. Instead, the flanges  540 A,  540 B extending outward from the housing  522  primarily define a securing interface relative to the nerve with the flanges  540 A,  540 B omitting any electrically conductive elements. In some examples, suture loops may be installed to further secure the flanges  540 A,  540 B in their closed position about the nerve  512 . 
     However, in some examples, a differently shaped housing may be substituted for the generally cylindrical shaped housing  522 . For instance, housing  522  may be replaced with a housing  1522  having an external surface with an arcuate nerve-engaging portion, such as described and illustrated in association with at least  FIGS. 19A-20B . With such an arrangement, the arcuate shape of the nerve-engaging portion enhances maintaining a stable, secure position of the housing  1522  relative to the nerve. In this way, the housing  1522  complements the action of flanges  540 A,  540 B in securing the stimulation therapy device  520  relative to nerve  512 . 
       FIG. 15A  is a diagram  600  schematically representing a microstimulation therapy device  620  implanted relative to a nerve  512  of array  510  of nerves within a subcutaneous, extravascular environment  502 , according to one example of the present disclosure. In some examples, the microstimulation therapy device  620  comprises at least some of substantially the same features and attributes as the previously described microstimulation therapy devices  100 ,  200  and/or therapy device  520  ( FIGS. 14A-14B ). As shown in  FIG. 15A , therapy device  620  includes a housing  622  extending between opposite ends  623 A,  623 B with housing  622  having a generally electrically non-conductive outer surface  624 . In some examples, no electrically conductive elements (such as ring electrodes  532  in  FIG. 14A ) are present on external surface  624 . However, in some examples, the entire external surface  624  or substantially the entire external surface  624  can be electrically conductive and serve as a single electrode. 
     As shown in both  FIGS. 15A-15B , a pair of flanges  640 A,  640 B extends outwardly from the housing  622  of therapy device  620  and are biased to encircle and releasably engage nerve  512  to mechanically (and directly) secure the housing  622  relative to, and in contact against, nerve  512  such that electrodes  644  on the flange  640 B become directly electrically coupled relative to the nerve  512 . In one aspect, the array  642  of electrodes  644  are spaced apart from each other and arranged in a radial pattern along the length of the flanges  640 A,  640 B to at least partially surround or encircle the circumference of the nerve  512  for applying a stimulation therapy to treat sleep disordered breathing (SDB). Accordingly, in some examples, the array  642  provides one example implementation of the radial array  432  in  FIG. 13 . 
     It will be understood that housing  622  contains a stimulator (e.g.  100 ,  200  in  FIGS. 5, 8 ) and that an electrical connection extends from the stimulation circuitry (within housing  622 ) through the flange  640 B to the respective electrodes  644  and/or through flange  640 A if some electrodes  644  are located on flange  640 A. In some examples, each electrode  644  may be independently controlled in applying a stimulation signal to the nerve  512 . As noted elsewhere, in at least some examples, the stimulator is encapsulated within non-conductive material within the housing  622 . 
     In one aspect, the housing  622  of microstimulation therapy device  620  is held directly against nerve  512  (which is to be stimulated) even though no stimulation is applied via the external surface  624  of the housing  622  of the therapy device  620 . As previously described in association with at least  FIGS. 14A-14B , the housing  622  may be substituted for a housing having a concave, arcuate cross-sectional shape which betters conforms or complements the arcuate outer surface of the nerve  512 . One such substitute housing may correspond to the housing in at least the example(s) later described and illustrated in association with at least  FIGS. 19A-20B . 
     With general reference to at least some examples of  FIGS. 15A-15B , no electrically conductive element extends axially beyond either end  623 A,  623 B of the housing  622 . In one aspect, this arrangement gives the therapy device  620  (including electrodes  644 ) a small footprint. In one aspect, this small footprint may enable a small electromagnetic footprint, at least in the sense that less heating may result from the relatively short lead loop length, thereby mitigating potential nerve damage that might otherwise occur in the presence of relatively larger lead loop lengths. In addition, this arrangement may minimize and/or avoid a patient-to-patient variability that commonly occurs in routing a lead in pectorally implanted therapy devices, in which such patient-to-patient variability may produce uncertainty in MR-conditional testing. Accordingly, at least some examples of the present disclosure, such as at least the arrangement in  FIGS. 15A-15B , may enable a microstimulation therapy device to receive a MR-conditional rating, in which the patient may be eligible for at least some types of MR scanning. 
     With general reference to at least some examples of  FIGS. 14A-14B, 15A-15B , in some implementations, the flanges ( 540 A,  540 B in  FIGS. 14A-14B ;  640 A,  640 B in  FIGS. 15A-15B ) do not extend a distance from the housing  522 ,  622  more than a length of housing  522 ,  622 . 
     With general reference to at least some examples of  FIGS. 15A-15 , in its closed position, the electrically conductive portions of the flange  640 B do not extend a distance from the housing  622  more than a diameter of nerve  512  or more than a diameter of the housing  622 . 
       FIG. 16A  is a diagram  700  schematically representing a microstimulation therapy device  720  implanted relative to a nerve  512  of array  510  of nerves within a subcutaneous, extravascular environment  502 , according to one example of the present disclosure. In some examples, the microstimulation therapy device  720  comprises at least some of substantially the same features and attributes as the previously described microstimulation therapy devices  100 ,  200 . As shown in  FIG. 16A , therapy device  720  includes a housing  722  extending between opposite ends  723 A,  723 B with housing  722  having a generally electrically non-conductive surface  724 . In some examples, at least one electrically conductive element (e.g. an electrode  747 ) is located on surface  724  in a position to directly engage nerve  512  when housing  722  is secured relative to nerve  512 . 
     As further shown in  FIGS. 16A-16B , a paddle  741  supports a grid array  742  of electrodes  744 , which face nerve  512  and which are opposite the electrode  747  on housing  722  thereby creating an arrangement in which various electrical vectors may be established across/though nerve  512 . Via independent programming of the various electrodes  744 ,  747 , stimulation electrical vectors may be established among and between the electrodes  744  on paddle  741  and/or stimulation electrical vectors may be established between electrode  747  and at least one of the electrodes  744  on paddle  741 . The paddle  741  is supported by arm(s)  745  which extend outwardly from housing  722  of therapy device  720  by a distance to place the paddle  741  on an opposite side of the nerve  512  from housing  722  (and therefore electrode  747 ). The grid array  742  may comprise a 2×2, 3×3, etc. array of independently programmable electrodes  744 . 
     In some examples, this arrangement is secured within the subcutaneous environment  502  and/or relative to nerve  512  via mechanical tines (similar to  FIG. 18B ). Alternatively, in some examples the arrangement in  FIGS. 16A-16B  can be secured relative to nerve  512  or another structure within subcutaneous environment  502  via a suture affixed directly on the stimulator housing  722  or affixed on a separate arm extends from housing  722 . 
     It will be understood that the schematic representation in  FIG. 16A-16B  provides generous spacing between the paddle  741  and nerve  512  for illustrative clarity, but in at least some examples, in practice the arm  745  has a size (e.g. length) and/or shape to cause the paddle  741  (and electrodes  744  thereon) to be in releasable contact against nerve  512  to at least partially secure the device  720  relative to the nerve  512  and to implement operative electrical coupling of the electrodes  747 ,  744  relative to nerve  512 . 
       FIG. 17A  is a diagram  800  schematically representing a microstimulation therapy device  820  implanted relative to a nerve  512  of array  510  of nerves within a subcutaneous, extravascular environment  502 , according to one example of the present disclosure. In some examples, the microstimulation therapy device  820  comprises at least some of substantially the same features and attributes as the previously described microstimulation therapy devices  100 ,  200 . As shown in  FIG. 17A , therapy device  820  includes a housing  822  extending between opposite ends  823 A,  823 B with housing  822  having a generally electrically non-conductive outer surface  824 . In some examples, at least one electrically conductive element (e.g. an electrode  847 ) is located on outer surface  824  in a position to directly engage nerve  512  when housing  822  is secured relative to nerve  512 . In some examples, the entire surface or substantially the entire surface  824  can be electrically conductive and thereby serve as a single electrode 
     As further shown in  FIG. 17A , one end  849 A of a corkscrew-shaped flange  848  extends axially from one end  823 B of housing  822  and supports an axially spaced apart array  842  of electrodes  844 , which wrap about a surface of nerve  512 . In some examples, the flange  848  may sometimes be referred to as being helical. In some examples, flange  848  is biased to self-wrap about nerve  512 , which is further schematically depicted in  FIG. 17B , thereby placing the electrodes  844  in direct contact against nerve  512 .  FIG. 17C  provides further information  850  regarding at least some examples associated with the arrangement of  FIGS. 17A-17B . 
     In one aspect, at least the biasing force and self-wrapping behavior of the helical flange  848  at least partially secures the electrodes  844  relative to the nerve and at least partially secures the housing  822  of the therapy device  820  relative to the nerve  512 . In some examples, mechanical tines (similar to  FIG. 18B ) can be used to further secure the housing  822  relative to nerve  512 . Alternatively, in some examples the arrangement in  FIGS. 17A-17B  can be secured relative to nerve  512  or another structure within subcutaneous environment  502  via a suture affixed directly on the stimulator housing  822  or affixed on a separate arm extends from housing  822 . Accordingly, these arrangements act to further secure the housing  822  relative to the nerve  512  and/or relative to the subcutaneous environment  502  to facilitate direct engagement of electrode  847  on housing  822  against nerve  512 . 
     Via independent programming of the various electrodes  844 ,  847 , stimulation electrical vectors may be established among and between the electrodes  844  on flange  848  and/or stimulation electrical vectors may be established between electrode  847  (on housing  822 ) and at least one of the electrodes  844  on flange  848 . 
     While  FIG. 17A-17B  provide one schematic representation of the helical flange  848  in relation to nerve to illustrate the axial spacing of the electrodes, extension from housing, etc.,  FIGS. 17C-17D  provide a further schematic representation to more fully illustrate the helical configuration of flange  848  and to illustrate that in at least some examples, the flange  848  may have a width (W2) generally corresponding to or greater than a width (W1) of the electrodes  844  located on or forming part of flange  848 . As shown in at least  FIG. 17D , in some examples the electrodes  844  are located on an inner, nerve-engaging surface  845  of flange  848  and that outer surface  843  lacks such electrodes  844  (in at least some examples). 
     Moreover, it will be understood that the generous spacing shown in  FIG. 17A  between the flange  848  (including electrodes  844  thereon) and nerve  512  is provided for illustrative clarity and that in practice the flange  848  would directly contact and releasably engage the nerve  512 , such as depicted in at least  FIG. 17B . 
     In some examples, the device  820  may comprise more than one helical flange  848 , such as having two such flanges extend from opposite ends of the housing  822 . In some examples, both flanges  848  comprise at least one electrode along the length of the respective flange. However, in some examples, just one of the flanges  848  includes at least one electrode along its length, as shown in  FIGS. 17A-17D . 
     In some examples, the housing  822  is positioned to contact nerve  512  even when the housing  822  omits an electrode  847 . 
     In some examples, housing  822  omits electrode  847  and is not in contact with nerve. In some such examples, housing  822  is secured relative to a non-nerve structure, which may be some distance from nerve  512 . In such examples, the flange  848  may have a length sufficient to extend from the housing  822  to the nerve  512  while still permitting a more distal portion of the flange  848  to engage nerve  512  both mechanically and electrically via electrodes  844 . It will be understood in some such examples that an electrical connection extends through the length of flange  848  between the stimulator in housing  822  and the electrodes  844 . 
     In some examples, at least some of the above-described examples associated with the device  820  of  FIGS. 17A-17D  may be implemented via and/or complement at least some of the examples associated with the arrangement(s) described and illustrated in association with at least  FIG. 21A  and/or  FIG. 21B . Accordingly, various features associated with the arrangements in  FIGS. 17A-17D, 21A and/or 21B  may be combined in a complementary manner. 
       FIG. 18A  is a diagram  900  schematically representing a microstimulation therapy device  920  implanted relative to a nerve  512  of array  510  of nerves within a subcutaneous, extravascular environment  502 , according to one example of the present disclosure. In some examples, the microstimulation therapy device  920  comprises at least some of substantially the same features and attributes as the previously described microstimulation therapy devices  100 ,  200 . As shown in  FIGS. 18A-18B , therapy device  920  includes a housing  922  extending between opposite ends  923 A,  923 B and opposite side edges  924 A,  924 B. In one aspect, housing  922  has a generally electrically non-conductive surface  924  supporting an array  945  of electrically conductive elements  947  (e.g. electrodes) for stimulating nerve  512  when housing  922  is secured relative to nerve  512 , as shown in  FIG. 18C . 
     As further shown in  FIGS. 18A-18C , an array  925  of tines  926  extend from the housing  922  to facilitate mechanical fixation of the therapy device  920  relative to the subcutaneous environment  502  in a manner to juxtapose electrodes  947  in close proximity and/or contact against nerve  512 . In some examples, tines  926  are positioned at and extend from the opposite side edges  924 A,  924 B of housing  922 . In some examples, each tine is biased to extend in a particular orientation adapted to facilitate fixation within the subcutaneous environment  502 . While  FIGS. 18A-18C  depict tines  926  having a particular orientation, it will be understood that tines  926  may be formed, attached, or constructed with any orientation within a generally 360 degree orientation depending upon the particular fixation scheme. In some examples, all of the tines  926  have the same general orientation (e.g. angle) while in some examples, at least some of the tines  926  have an angle/orientation different than at least some other tines  926 .  FIG. 18D  provides further information  950  regarding at least some examples associated with the arrangement of  FIGS. 18A-18C . 
     Among other features, the housing  922  of therapy device  920  in  FIGS. 18A-18C  is provided in a generally planar shape having minimal thickness, which may enhance implantation by maintaining a relatively low profile. Moreover, in some examples, the housing  922  has a width extending between side edges  924 A,  924 B that is substantially greater (e.g. 2×, 3×, etc.) than a diameter of the nerve  512 , thereby providing enhanced lateral stability upon deployment of tines  926 . 
     With general reference to at least some examples associated with at least  FIGS. 14A-18D  as well as at least  FIGS. 19A-20B , the compact arrangement in which the housing of a stimulator of the microstimulation therapy device is located directly against the target nerve or in proximity to the nerve (as opposed to a pectoral location of a pulse generator) may enhance patient comfort and ease surgical implantation. 
     In at least some examples of the microstimulation therapy device described throughout the present disclosure, such as but not limited to,  FIGS. 5, 8, and 14A-18B , at least some of the electronics (e.g. circuitry, components, elements) within the housing of the stimulator of microstimulation therapy device  100 ,  200  and/or at least some electronic components external to the housing of the stimulator of therapy device  100 , 200  may be implemented as integrated passive devices on silicon, via chip stacking, and/or via flexible substrates. 
     In at least some examples of the microstimulation therapy device described throughout the present disclosure, such as but not limited to,  FIGS. 5, 8, 14A-18B , and  19 A- 20 C at least some examples of the housing of the stimulator of microstimulation therapy device  100 ,  200  includes: (A) feedthroughs mounted directly onto a printed circuit board (PCB) or electronics package; (B) feedthroughs connected to electronics via a process similar to solder reflow once there is direct contact between the feedthroughs and the board; and/or (C) active or smart lead technology that allows one or two feedthroughs to be multiplexed outside of the hermetic sealed assembly. 
     In at least some examples of the microstimulation therapy device described throughout the present disclosure, such as but not limited to,  FIGS. 5, 8, 14A-18B , and  19 A- 20 C, at least some examples of the electrodes external to the housing of the stimulator microstimulation therapy device include at least the following characteristics. For instance, in some examples an electrode structure (e.g. a lead) is integrated with the hermetically sealed housing, such as at least partially depicted in at least  FIGS. 15B, 16B, 17A-17B  in which a proximal end of a structure carrying electrodes (which are spaced apart from the housing) is electrically and mechanically coupled relative to (and extending outwardly from) the hermetic housing. 
     In another instance, in some examples, at least some electrodes are mounted directly on the hermetic housing so the housing acts like a paddle lead, such as at least partially depicted in  FIGS. 14A and 16A-18A, 19A-19C . In some such examples in which such electrodes form an array of electrodes, these electrodes can be attached to the electronics package (within housing) with a direct contact process like that used for electronics surface mount technologies (SMT) to avoid the need to utilize space for larger interconnect technologies like printed circuit board (PCB) through-hole soldering. 
     In another instance, in some examples in which at least a portion of the outer surface of the housing is not conductive, conductive traces (e.g. ceramic) and electrodes could be directly integrated into the housing so the housing could be used to distribute stimulation and/or sensing signals from the electronic package within the housing to electrode arrays along the housing or on an electrode structure or lead extending from the housing. 
     In some examples, at least the stimulation circuitry of a stimulator comprises flexible circuitry. In some such examples, a power element is not incorporated within such flexible circuitry. In some such examples, the power element is located along a centerline of a housing containing the flexible stimulation circuitry, and in some instances, this centerline may sometimes be referred to as a spine of the housing. 
       FIG. 19A  is a perspective view schematically representing a cuff electrode  975  of a stimulation therapy device  976 , according to one example of the present disclosure. 
     As shown in  FIG. 19A , cuff electrode  975  comprises a housing  980  to contain at least some features and attributes of a stimulator (e.g.  100  in  FIG. 5 ;  200  in  FIG. 8 ) with housing  980  having an arcuate nerve-engaging surface  982  shaped (e.g. an arcuate cross-sectional shape) to correspond to an arcuate outer surface (e.g. circumference) of a nerve  989 . The arcuate nerve-engaging surface  982  facilitates robust, secure engagement of the housing  980  relative to nerve  989 . Housing  980  extends between a first end  981 A and an opposite second end  981 B. In some examples, housing  980  comprises a non-engaging surface  983  opposite the nerve-engaging surface  982 . In some examples, the non-nerve-engaging surface  983  comprises an arcuate cross-sectional shape. In some examples, this arcuate cross-sectional shape of non-nerve-engaging surface corresponds to the arcuate cross-sectional shape of the nerve-engaging surface  982 . 
     In some examples, the housing  980  may comprise a generally uniform thickness over at least 50 percent of a cross-sectional area of the housing  980 . 
     In some examples, cuff electrode  975  comprises a flange  990 . The flange  990  comprises a first side portion  992  extending from a first side  984 A of an outer surface  983  of housing  982  and an opposite second side portion  993  releasably engageable relative to an opposite second side  984 B of outer surface  983  of housing  982 . The flange  990  has a generally arcuate cross-sectional shape including a nerve-engaging surface  997  sized to extend across the opening  987  defined between opposite end portions  988 A,  988 B of housing  980 . 
     In some examples, the flange  990  is a separate member and the first side portion  992  of flange  990  is then secured relative to the first side  984 A of housing  982 . However, in some examples, the first side portion  992  of flange  990  is molded with housing  982  such that housing  980  and flange  990  together form a single unitary molded piece (e.g. a monolithic structure). 
     In either case, the first side portion  992  of flange  990  is flexibly bendable relative to first side  984 A of housing  982  to enable moving the flange  990  between a closed position (represented in  FIG. 19A  via solid lines) covering the opening  987  between end portions  988 A,  988 B of housing  980  and an open position (represented via dashed lines  999 ) pivoted away from opening  987  to permit maneuvering the housing  982  on and off the nerve  989  during implantation. In some examples, the flexibly bendable functionality may sometimes be referred to as being a living hinge. 
     In some examples, in cooperation with first side  984 A of housing  982 , the flange  990  is biased in the closed position (represented by solid lines) but can be moved into the open position to mount or dismount the relative to the nerve  989 . 
     In some examples, cuff electrode  975  forms at least a portion of a therapy device having at least some of substantially the same features and attributes as therapy device  520  in  FIGS. 14A-14B . In some examples, cuff electrode  975  comprises at least a partial implementation of the therapy device  520  of  FIGS. 14A-14B . However, in the example shown in  FIG. 19A , the therapy device  975  comprises just one flange  990  instead of two flanges  540 A,  540 B in  FIG. 14A-14B . However, it will be understood that in some examples, instead of having a single flange  990 , cuff electrode  975  may include two flanges  990  oriented in opposite directions to at least partially overlap each other. 
     In addition, in the example shown in  FIG. 19A , the cuff electrode  975  omits ring electrodes  532  on housing  980  and instead provides at least one electrode on nerve-engaging surface  982  while omitting electrodes on outer surface  983  (e.g. a non-nerve engaging surface) of housing  980 . For illustrative clarity, the at least one electrode is omitted from  FIG. 19A . 
     However, as shown in the sectional views of  FIGS. 19B and 19C , in some examples the at least one electrode comprises an array  1000  of electrodes  1001 . In some examples, as shown in  FIG. 19B , the electrodes  1001  may be axially spaced apart along a length (L) nerve-engaging surface  982  of the housing  980 . In some examples, as shown in  FIG. 19B , an array  1005  of electrodes  1006  may be spaced apart in a radial pattern extending transversely along nerve-engaging surface  982 . In some examples, the at least one electrode may comprise a grid array like that in  FIGS. 18A-18B  such that both axially spaced apart electrodes  1001  and radially spaced apart electrodes  1005  are present in a grid (e.g. 2×2, 3×3, etc.) on nerve-engaging surface  982 . In some examples, other than having different locations, there is no difference between the functionality of electrodes  1001  as compared to electrodes  1005 , with any various combination of electrodes  1001  and/or electrodes  1005  functioning in a complementary manner. In some examples, electrodes  1001  and/or electrodes  1005  are independently programmable to implement a neurostimulation therapy. 
     In some examples, just a single electrode  1001  or  1005  is located on nerve-engaging surface  982 . In some such examples, cuff electrode  975  comprises additional electrodes, such as on nerve-engaging surface  997  of flange  990 , which function in a complementary manner with the single electrode ( 1001  or  1005 ) on nerve-engaging surface  982 . 
     In some examples, the at least one electrode of cuff electrode  975  is located on the nerve-engaging surface  997  of flange  990  instead of on nerve-engaging surface  982  of the housing  982 . In some examples, the at least one electrode on nerve-engaging surface  997  may comprise an axially spaced apart array  1000  of electrodes  1001  as shown in the sectional view of  FIG. 19B  and/or a radially spaced apart array  1005  of electrodes  1005  as shown in the sectional view of  FIG. 19C . 
     In some examples, both the nerve-engaging surface  982  of housing  980  and the nerve-engaging surface  997  of flange  990  include at least one electrode (e.g.  1001  or  1005 ), which may be a single electrode on each respective nerve-engaging surface  982 ,  997  or which may be an array ( 1000  and/or  1005 ) of electrodes on each of nerve-engaging surface  982 ,  997   
     It will be understood that the schematic representation in  FIG. 19A  provides generous spacing between an outer surface of nerve  989  and the nerve-engaging surface  982  (of housing  980 ) and nerve-engaging surface  997  (of flange  990 ) for illustrative clarity. However, in at least some examples, in practice the housing  980  and/or flange  990  are sized and shaped to, cause nerve-engaging surfaces  982 ,  997  to directly contact and releasably engage the arcuate outer surface of nerve  989  to grippingly secure the cuff electrode  975  about the nerve  989 . 
     In some examples, at least a portion of the housing  980  and/or flange  990  comprises a flexible, resilient material which may enable at least one of the nerve-engaging surfaces  982 ,  997  to at least partially conform about the nerve  989  to more securely engage the nerve  989 . 
     As further shown in the sectional view of  FIG. 19B , in some examples housing  980  comprises a body  987  internal to outer surface  983  and nerve-engaging surface  982 . In some examples, as schematically represented via  FIG. 19B , a stimulator  1003  (e.g.  100 ,  200  in  FIGS. 5, 8 ) is located within body  987  and thereby contained within housing  980 . It will be understood that in some examples, the various elements comprising a stimulator  1003  may be distributed throughout body  987  and are not necessarily consolidated in a single monolithic structure. The stimulator  1003  is electrically connected to the electrodes  1001  (or  1005  in  FIG. 19C ) via body  987  so that nerve-engaging surface  982  is non-conductive except of the surfaces of electrodes  1001 ,  1005 . 
       FIG. 20A  is a perspective view schematically representing a cuff electrode  1021  of a stimulation therapy device  1020  in an open position (A) and a closed position (B), according to one example of the present disclosure. 
     In some examples, the cuff electrode  1021  comprises at least some of substantially the same features as cuff electrode  975  with a few exceptions. In one exception, cuff electrode  1021  provides a flange  1030  like flange  990  except with a hinge  1033  at a junction of an end portion  988 B of the housing  982  and an end portion  1031 A of flange  1030 . In some examples the flange  1030  comprises a generally rigid member. In some examples, flange  1030  comprises a semi-rigid, resilient member. In view of the end-to-end connection of the flange  1030  relative to the housing, the flange  1030  may sometimes be referred to as a cover. 
     Together with hinge  1033 , this cover  1030  may sometimes be referred to as a closable clasp which releasably locks into the closed position (B) in which end portion  1031 B of flange  1030  is firmly engaged against end portion  988 A of housing  982 . Accordingly, in some examples, the hinge  1033  permits rotation of cover  1030  between the open and closed position, with cover  1030  biased to remain in the closed position until or unless a sufficient force is applied to overcoming the biasing force of hinge  1033  such that the cover  1030  moves to the open position (A). 
     In some examples, the structure and functionality of hinge  1033  is implemented via a shape memory material formed as part of housing  982  and/or flange  1030 , and with such material extending between and/or forming the junction of the end portion  988 B of housing  982  and end portion  1031 A of flange  1030 . In some examples, the shape memory material may comprise a metal material such as, but not limited to, Nitinol while in some examples, the shape memory material may comprise a non-metal material. 
     In some examples of the cuff electrode  1021  of  FIG. 20A , the axial array of electrodes  1001  ( FIG. 19B ) and/or the radial array of electrodes  1005  ( FIG. 19C ) may be implemented on a nerve-engaging surface  982  of the housing  980 . In some examples, the axial array of electrodes  1001  ( FIG. 19B ) and/or the radial array of electrodes  1005  ( FIG. 19C ) may be implemented on a nerve-engaging surface  1037  of the flange  1030 . In some examples, both respective nerve-engaging surfaces  982 ,  1037  includes at least some electrodes, whether in the axial array configuration ( FIG. 19B ), the radial array configuration ( FIG. 19C ), or some other combination of electrodes. 
       FIG. 20B  is a perspective view schematically representing a cuff electrode  1051  of a stimulation therapy device  1050 , according to one example of the present disclosure. In some examples, the cuff electrode  1051  comprises at least some of substantially the same features and attributes as the stimulators of the therapy devices described in association with  FIGS. 1-18  and/or in association with  FIG. 21A-25B . In some examples, the cuff electrode  1051  comprises one example implementation of at least some of the features and attributes of the therapy device described in association with at least  FIGS. 14A-14B or 15A-15B . 
     In some examples, cuff electrode  1051  comprises a housing  1060  defining a nerve-engaging surface  1062 , including a first nerve-engaging portion  1065 , a pair of second nerve-engaging portions  1067 A,  1067 B, and a third pair of nerve-engaging portions  1069 A,  1069 B. In one aspect, these various nerve-engaging portions  1065 ,  1067 A,  1067 B,  1069 A,  1069 B work together to releasably engage a nerve  989 . In some examples, the portion of cuff electrode  1051  including nerve-engaging portions  1067 A,  1067 B, and  1069 A,  1069 B may sometimes be referred to as arms  1059 A,  1059 B which extend from a body  1064  of housing  1060 . In some examples, in their open position (A), the arms  1059 A,  1059 B may extend generally parallel to each other, or even diverge from each other to provide an ample opening  1087  to mount and dismount cuff electrode  1051  relative to nerve  989  such as during implantation, etc. 
     In a manner similar to that shown in  FIG. 19B , body  1064  may contain (e.g. encapsulate) a stimulator (e.g. at least  100 ,  200  in  FIGS. 5, 8   1003  in  FIG. 19B ). As noted elsewhere and as applicable to any of the examples of the present disclosure, in some examples, except for any electrodes present on a nerve-engaging surface of the housing  1060 , the entire external surface  1063  of housing  1060  defines a non-conductive surface. As noted elsewhere and as applicable to any of the examples of the present disclosure, in some examples body  1064  comprises a non-conductive material in which the stimulator is contained or encapsulated internally within housing  1060 . 
     In some examples, the respective pivot portions  1071 A,  1071 B and pivot portions  1070 A,  1070 B permit rotation of end portions  1088 A,  1088 B of arms  1059 A,  1059 B between the open position (A) and closed position (B). Once cuff electrode  1051  is installed onto nerve  989  in a closed position (B), the arms  1059 A,  1059 B are biased to remain in the closed position (B) until or unless a sufficient force is applied to overcoming the biasing force of hinge  1033  such that the end portions  1088 A,  1088 B move to the open position (A). However, it will be understood that the open position (A) may be typically employed primarily during initial implantation and maneuvering of the cuff electrode  1051  relative to nerve  989 . 
     In some examples, the structure and functionality of pivot portions  1070 A,  1070 B,  1071 A, and  1071 B may be implemented via a shape memory material formed as part of housing  1060 . In some examples, the shape memory material may comprise a metal material such as, but not limited to, Nitinol while in some examples, the shape memory material may comprise a non-metal material In some examples, at least some of the pivot portions  1070 A,  1070 B,  1071 A,  1071 B may be sometimes be referred to as a living hinge. 
     While not shown in  FIG. 20B , in some examples, the first nerve-engaging portion  1065  of housing  1060  comprises an arcuate shaped surface in a manner similar to nerve-engaging surface  982  of housing  980  in  FIGS. 19A-19C . In some examples, the respective second nerve-engaging portions  1067 A,  1067 B of housing  1060  comprise an arcuate shaped surface in a manner similar to nerve-engaging surface  982  of housing  980  in  FIGS. 19A-19C . In some examples, the respective third nerve-engaging portions  1069 A,  1069 B of housing  1060  comprise an arcuate shaped surface in a manner similar to nerve-engaging surface  982  of housing  980  in  FIGS. 19A-19C . 
     In some examples, the respective first, second and third nerve-engaging surfaces  1065 ,  1067 A,  1067 B,  1069 A,  1069 B have a contour which gradually blends into the adjacent respective nerve-engaging surface such that the respective first, second, and third nerve-engaging surfaces do not act as discretely different surfaces. 
     In some examples, the cuff electrode  1051  provides an arrangement in which the arms  1059 A,  1059 B and body  1064  form a single unitary piece (e.g. a monolithic element) which can releasably engage a nerve. 
       FIG. 20C  is a partial end view schematically representing two arms of cuff electrode  1090  for a microstimulation therapy device  1060 , according to one example of the present disclosure. As shown in  FIG. 20C , the two end portions  1088 A,  1088 B of arms  1059 A,  1059 B point toward each other, and even may contact in some examples. In some examples, the two end portions  1088 A,  1088 B may even overlap. 
     In some examples of the cuff electrode  1061  of  FIG. 20B , the axial array of electrodes  1001  ( FIG. 19B ) and/or the radial array of electrodes  1005  ( FIG. 19C ) may be implemented on a nerve-engaging surface  1062  of the housing  1060 , whether on portion  1065 , portions  1067 A,  1067 B, and/or portions  1069 A,  1069 B. 
       FIG. 21A  is a diagram  1100  schematically representing a microstimulation therapy device  1120  implantable relative to a nerve within a subcutaneous, extravascular environment  1102 , according to one example of the present disclosure. In some examples, the microstimulation therapy device  1120  comprises at least some of substantially the same features and attributes as the previously described microstimulation therapy devices  100 ,  200 . 
     As shown in some examples, the microstimulation therapy device  1120  forms part of an arrangement  1121  including a lead  1130  and a cuff electrode  1140 . 
     In general terms, cuff electrode  1140  includes some non-conductive structures biased to (or otherwise configurable to) releasably secure the cuff electrode  1140  about a target nerve  30  ( FIGS. 1-4 ) and includes an array of electrodes to deliver a stimulation signal to the target nerve. In some examples, the cuff electrode  1140  may comprise at least some of substantially the same features and attributes as described within at least U.S. Pat. No. 8,340,785 issued on Dec. 25, 2012 and/or U.S. Patent Publication 2011/0147046 published on Jun. 23, 2011. 
     The lead  1130  extends between the cuff electrode  1140  and microstimulator  1120  with lead  1130  having a length (X1). In some examples, length X1 may be up to 20 centimeters to enable anchoring the microstimulator to a bony structure (or other sturdy tissue) a short distance from the target nerve and cuff electrode  1140 . In some examples, length X1 may be 10 centimeters or less for other anchoring arrangements and/or electrode cuff deployments. 
     As further shown in  FIG. 21A , the arrangement  1121  may further include an anchor(s)  1160  by which microstimulator  1120  is secured relative to a bodily structure  1162  (e.g. bony structure or other sturdy tissue) within the subcutaneous environment  1102 . In some examples, the anchor  1160  may include a loop element to facilitate deployment of fastening mechanism relative to the bodily structure  1162 . 
       FIG. 21B  is a diagram  1200  schematically representing an implanted microstimulation therapy device  1220  secured relative to a bony structure  1230  within a subcutaneous environment  1202 , according to one example of the present disclosure. In some examples, the microstimulation therapy device  1220  comprises at least some of substantially the same features and attributes as the previously described microstimulation therapy devices  100 ,  200 . As shown in  FIG. 21B , a screw  1240  or analogous mechanical fastener fixes the microstimulator  1220  against a bony structure  1230 , which may be a mandible  1232 , cranium  1234 , or other bony tissue  1236 . 
       FIG. 22  is a diagram  1300  schematically representing arrangements for an antenna associated with a microstimulation therapy device  1320 , according to one example of the present disclosure. In some examples, the microstimulation therapy device  1320  comprises at least some of substantially the same features and attributes as the previously described microstimulation therapy devices  100 ,  200 . In some examples, as shown in  FIG. 22  in some examples, microstimulator  1320  forms part of an arrangement including an antenna  1333 A or  1333 B, and which may include other elements (e.g. lead, electrodes, anchors, etc.) as described throughout the present disclosure. 
     As shown in  FIG. 22 , in a manner at least consistent with at least some previously described examples, the microstimulator  1320  is electrically coupled and mechanically coupled relative to a nerve  30  for applying a therapeutic stimulation signal to nerve  30 . Moreover, microstimulator  1320  receives energy via an antenna arranged to facilitate fast charging and/or energy harvesting protocols. Accordingly, in one arrangement an antenna  1333 A is positioned (e.g. secured) within the subcutaneous environment  1302  close to skin  70  in a general location  1343  of the head/neck region so that the antenna  1333 A is readily accessible by an externally located energizing device  1343  for charging and/or energy harvesting. In this arrangement, antenna  1333 A is in electrical communication with microstimulator  1320  via a pathway  1325 , which may be wired or wireless. 
     In another arrangement, an antenna  1333 B is positioned (e.g. secured) within the subcutaneous environment  1302  close to skin  70  but in a cochlear location  1346  of the head/neck region so that the antenna  13336  is readily accessible by an externally located energizing device  1343  for charging and/or energy harvesting. In this arrangement, antenna  13336  is in electrical communication with microstimulator  130  via a pathway  1327 , which may be a wired pathway. 
     In either arrangement, in some examples, the antenna is reasonably close to the skin to facilitate a fast rate of energy transfer relative to the energizing device  1343  and/or the antenna is relatively remote from the nerve  30  and/or microstimulator  1320 . 
     It will be understood that in at least some examples, various features and attributes among the different examples throughout at least  FIGS. 1-22  and/or throughout  FIGS. 23A-27 , may be combined in different configurations on a feature-by-feature manner. 
     It also will be understood that in the examples described throughout the present disclosure, at least any implantable elements exposed to tissue, fluids, etc. within the human body will be made of biocompatible materials, whether polymer and/or metal. 
       FIG. 23A  is a diagram  1400  schematically representing a microstimulation therapy device  1420  implanted within at least a portion of the vasculature within a head/neck region  24 , according to one example of the present disclosure. In some examples, the microstimulation therapy device  1420  comprises at least some of substantially the same features and attributes as the previously described microstimulation therapy devices  100 ,  200 . 
     As shown in  FIG. 23A , microstimulation therapy device  1420  forms part of an arrangement  1421  also including a lead  1430  and an electrode array  1434 . The lead  1430  extends distally from a housing of the therapy device  1420  and with a distal portion  1432  of the lead  1430  supporting the electrode array  1434  of electrodes  1436 . In some examples, the array  1434  includes several axially spaced apart electrodes  1436 , although other electrode configurations may be used. 
     As shown in  FIG. 23A , microstimulation therapy device  1420  has been implanted such that the entire arrangement  1421  resides within the vasculature  1404 , with distal electrode array  1434  positioned within a vein  1406  adjacent a target nerve  1412  of an array  1410  of nerves, such that electrical stimulation may be applied to nerve  1412  from the intravascular location of the distal electrode array  1434 . Accordingly, in some instances, such stimulation may sometimes be referred to as a transvascular application of a therapeutic stimulation signal. 
     In one aspect, in a manner similar to at least some examples previously described herein, the relatively small size and/or shape of the microstimulator device  1420  facilitates a minimally invasive implantation procedure in which the arrangement  1421  may be implanted within the vasculature  1404  within the head/neck region  24  without involving other parts of the patient&#39;s body. Accordingly, in some examples, the entire arrangement  1421  (including microstimulation therapy device  1420 ) resides entirely within the peripheral vasculature. 
     In some examples, the housing of the microstimulation therapy device  1420  is secured within the vasculature via an anchor  1422 , which may comprise at least one of tines, barbs, stents, and/or other fixation mechanisms. 
     However, it will be understood that in some examples, the microstimulation therapy device  1420  may be secured within a more central portion of the patient&#39;s vasculature to accommodate some implementations in which a housing of the therapy device  1420  has a relatively larger size. As such, in some implementations, the therapy device  1420  may reside within a portion of the vasculature extending in a portion of the body other than the head/neck region. 
       FIG. 23B  is a diagram  1450  schematically representing a microstimulation therapy device  1470  implanted within at least a portion of the vasculature within a head/neck region, according to one example of the present disclosure. In some examples, the microstimulation therapy device  1470  comprises at least some of substantially the same features and attributes as the previously described microstimulation therapy devices  100 ,  200 . 
     As shown in  FIG. 23B , microstimulation therapy device  1470  forms part of an arrangement  1471  also including a lead  1460  and an electrode array  1434 . The lead  1460  extends distally from a housing of the therapy device  1470  and with a distal portion  1432  of the lead  1460  supporting the electrode array  1434  of electrodes  1436 . In some examples, the array  1434  includes several axially spaced apart electrodes  1436 , although other electrode configurations may be used. 
     As shown in  FIG. 23B , microstimulation therapy device  1470  has been implanted such that the just the distal electrode array  1434  (and a portion of lead  1460 ) resides within the vasculature  1404 , and in particular within vein  1406  adjacent the target nerve  1412  of an array  1410  of nerves, such that electrical stimulation may be applied to nerve  1412  from the intravascular location of the distal electrode array  1434 . Accordingly, in some instances, such stimulation may sometimes be referred to as a transvascular application of a therapeutic stimulation signal. 
     In some examples, the housing of the microstimulation therapy device  1470  is secured external to the vasculature  1404  within the subcutaneous environment  1402  via an anchor  1472 , which may comprise at least one of tines, barbs, screws, and/or other fixation mechanisms. In some examples, when the anchor comprises a screw(s), the housing of the therapy device  1470  is secured relative to a bony structure, such as but not limited to, the mandible (either modified or unmodified), the cranium, and/or other bony structures suited to position the microstimulation therapy device  1470  in reasonably close proximity to the target nerve  1412  and vein  1406  in which lead  1460  and electrode array  1434  extend. 
     In one aspect, in a manner similar to at least some examples previously described herein, the relatively small size and/or shape of the microstimulator device  1470  facilitates a minimally invasive implantation procedure in which the arrangement  1471  may be implanted within the subcutaneous environment  1402  within the head/neck region  24  without involving other parts of the patient&#39;s body and via a location reasonably close the target nerve  412  to be stimulated. Accordingly, in some examples, the entire arrangement  1471  (including microstimulation therapy device  1420 ) resides entirely within head/neck region  24 . In addition, the relatively small size of the microstimulation therapy device  1470  enables its subcutaneous implantation (via a percutaneous access or analogous minimally invasive technique) in a location reasonably close to the vascular entry point  1407  at which distal electrode array  1434  can be placed promptly adjacent the targeted nerve  1412 , thereby saving much time and effort in achieving a therapeutically efficacious implantation. 
       FIG. 24  is a block diagram of a therapy manager  1600 , according to one example of the present disclosure. In some examples, therapy manager  1600  may be implemented as therapy manager  122  in the therapy devices  100 ,  200  of  FIGS. 5 and 8  and/or therapy manager  1600  comprises at least substantially the same features and attributes as therapy manager  122  in therapy devices  100 ,  200 . In some examples, therapy manager  1600  is implemented as therapy manager  1705  in control portion  1700  in  FIG. 25A  and/or comprises at least some of substantially the same features and attributes as therapy manager  1705  in  FIG. 25A . While not necessarily expressly stated directly in association with  FIG. 24 , it will be understood that therapy manager  1600  may utilize and/or coordinate with at least some of the therapy-related features, functions, attributes, parameters, etc. as described throughout at least some examples of the present disclosure. 
     In some examples, at least some of the features and functions of therapy manager  1600  are accessed via user interface  1710  in  FIG. 25B . 
     As shown in  FIG. 24 , in some examples, therapy manager  1600  includes a stimulation intensity function  1610 , an open loop module  1620 , and a closed loop module  1630 . 
     In some examples, once therapy is initiated during a daily treatment period, stimulation is performed generally continuously. In some examples, once therapy is initiated during a daily sleep period, stimulation is performed on an “as-needed” basis, such that stimulation occurs when needed but is otherwise suspended. 
     In some examples, the open loop module  1620  causes a microstimulation therapy device to apply therapeutic stimulation without receiving and/or sensing physiologic information. 
     In some examples, the closed loop module  1630  causes a microstimulation therapy device to apply therapeutic stimulation, at least in part, based on received and/or sensed physiologic information related to the intended therapy. As shown in  FIG. 24 , in some examples the close loop module  1630  includes a stimulation timing function  1640 , an automatic stimulation on/off function  1650 , a respiratory information parameter  1660 , an auto-titrate function  1662 , a power management function  1664 , and/or a sleep position parameter  1670 . 
     In some examples, via at least stimulation timing function  1640 , stimulation is synchronized relative to a sensed onset of inspiration in the respiratory cycle. In some instances, via at least stimulation timing function  1640  initiation, termination, and/or duration of stimulation are based on a sensed respiratory waveform but are not synchronized relative to each inspiratory phase. 
     However, in some instances, via at least stimulation timing function  1640 , stimulation is generally synchronized with inspiration. 
     In some instances, via at least stimulation timing function  1640 , whether or not stimulation is synchronized with inspiration, stimulation is triggered according to a time sequence at least partially based on at least one of a beginning of inspiration, an end of inspiration, a beginning of expiration, and/or an end of expiration. 
     In some examples, via an automatic stimulation state function  1650 , stimulation is enabled and disabled (e.g. turned on and off) automatically according to various parameters. In some examples, such parameters include posture, respiratory rate, apnea-hypopnea event count, etc. However, in some examples, because sleep disordered breathing is generally associated with sleep periods of the patient, in some examples a treatment period automatically coincides with a daily sleep period of the patient with the automatic stimulation state function  1650  then enabling/disabling stimulation according to the above-identified parameters. In some instances, the daily sleep period is identified via sensing technology which detects motion, activity, posture, position of the patient, as well as other indicia, such as heart rate, breathing patterns, etc. However, in some instances, the daily sleep period is selectably preset, such from 10 pm to 6 am or other suitable times. 
     In some examples, the respiratory information parameter  1660  includes respiratory waveform information and/or tracks respiratory effort including respiratory patterns (e.g., inspiration, expiration, respiratory pause, etc.) and is obtained via a sensing function (e.g.  205  in  FIG. 8 ). In some examples, this respiratory information is employed to trigger activation of stimulation circuitry (e.g.  112  in  FIG. 8 ) to stimulate a target nerve (e.g.  30  in  FIGS. 1-4 ) and/or is employed in various ways as described throughout at least some examples of the present disclosure. 
     In some examples, via at least the power management parameter  1664 , a characteristic of a sensed respiratory waveform (e.g. via respiratory information parameter  1660 ) is used to reduce at least one parameter regarding an intensity of stimulation pulses (per stimulation intensity function  1610 ) to reduce power requirements. In some examples, such respiratory characteristics include apnea-hypopnea event detection, inspiratory onset detection, etc. In some examples, the at least one parameter of stimulation intensity function  1610  includes a pulse amplitude, number of pulses, pulse width, burst time, and/or electrode configuration. 
     In some examples, via at least the sleep position parameter  1670 , the therapy manager includes a posture-adjustment function to enable adjusting stimulation timing (per  1640 ) and/or intensity (per  1610 ) in accordance with changing sleep postures/positions throughout the night. 
     In some examples, via an auto-titrate parameter  1662 , a characteristic of a sensed respiratory waveform (per parameter  1660 ) enables performing an auto-titration protocol via at least one parameter of stimulation intensity (per function  1610 ). In some examples, such characteristics include apnea-hypopnea event detection, inspiratory onset detection, etc. In some examples, the at least one parameter of stimulation intensity ( 1610 ) includes a pulse amplitude, number of pulses, pulse width, burst time, and/or electrode configuration. 
       FIG. 25A  is a block diagram schematically representing a control portion  1700 , according to one example of the present disclosure. In some examples, control portion  1700  includes a controller  1702  and a memory  1704 . In some examples, control portion  1700  provides one example implementation of a control portion forming a part of, or implementing, any one of managers, control portions, and/or therapy devices/systems, as represented throughout the present disclosure in association with  FIGS. 1-23 . 
     In general terms, controller  1702  of control portion  1700  comprises at least one processor  1703  and associated memories. The controller  1702  is electrically couplable to, and in communication with, memory  1704  to generate control signals to direct operation of at least some components of the systems, devices, components, functions, and/or modules described throughout the present disclosure. In some examples, these generated control signals include, but are not limited to, employing manager  1705  stored in memory  1704  to manage therapy for sleep disordered breathing in the manner described in at least some examples of the present disclosure. It will be further understood that control portion  1700  (or another control portion) may also be employed to operate general functions of the various therapy devices/systems described throughout the present disclosure. 
     In response to or based upon commands received via a user interface (e.g. user interface  1710  in  FIG. 25B ) and/or via machine readable instructions, controller  1702  generates control signals to implement therapy implementation, monitoring, and/or management in accordance with at least some of the previously described examples of the present disclosure. In some examples, controller  1702  is embodied in a general purpose computing device while in some examples, controller  1702  is incorporated into or associated with at least some of the associated components of the therapy devices and/or managers described throughout the present disclosure. 
     For purposes of this application, in reference to the controller  1702 , the term “processor” shall mean a presently developed or future developed processor (or processing resources) that executes sequences of machine readable instructions contained in a memory. In some examples, execution of the sequences of machine readable instructions, such as those provided via memory  1704  of control portion  1700  cause the processor to perform actions, such as operating controller  1702  to implement sleep disordered breathing (SDS) therapy and/or monitoring, as generally described in (or consistent with) at least some examples of the present disclosure. The machine readable instructions may be loaded in a random access memory (RAM) for execution by the processor from their stored location in a read only memory (ROM), a mass storage device, or some other persistent storage (e.g., non-transitory tangible medium or non-volatile tangible medium, as represented by memory  1704 . In some examples, memory  1704  comprises a computer readable tangible medium providing non-volatile storage of the machine readable instructions executable by a process of controller  1702 . In other examples, hard wired circuitry may be used in place of or in combination with machine readable instructions to implement the functions described. For example, controller  1702  may be embodied as part of at least one application-specific integrated circuit (ASIC). In at least some examples, the controller  1702  is not limited to any specific combination of hardware circuitry and machine readable instructions, nor limited to any particular source for the machine readable instructions executed by the controller  1702 . 
       FIG. 25B  is a block diagram schematically representing user interface  1710 , according to one example of the present disclosure. In some examples, user interface  1710  forms part or and/or is accessible via a device external to the patient and by which the microstimulation therapy device  100 ,  200  may be at least partially controlled and/or monitored. The external device hosing user interface  1710  may be a patient remote and/or a clinician portal. 
     In some examples, user interface  1710  comprises a user interface or other display that provides for the simultaneous display, activation, and/or operation of at least some of the various components, modules, functions, parameters, features, and attributes of manager ( 122  in  FIGS. 5, 8 ;  1600  in  FIG. 24 ) and/or control portion ( 120  in  FIGS. 5, 8 ;  1700  in  FIG. 25A ). In some examples, at least some portions or aspects of the user interface  1710  are provided via a graphical user interface (GUI). In some examples, as shown in  FIG. 25B , user interface  1710  includes display  1712  and input  1714 . 
     In some instances, at least some examples of a microstimulation therapy device as described in association with at least  FIGS. 1-25  may be employed to perform vagal nerve stimulation and/or baroreceptor-based therapy. 
       FIG. 26  is a block diagram schematically representing aspects of a method  2500  of microstimulation, according to one example of the present disclosure. In some examples, at least some aspects of method  2500  may be implemented via at least some of the systems, apparatuses, devices, stimulators (including microstimulators), sensors, power elements, functions, parameters, components, elements, etc. as described throughout the examples of the present disclosure in association with  FIGS. 1-25B . In some examples, at least some aspects of method  2500  may be implemented via at least some systems, apparatuses, devices, stimulators (including microstimulators), sensors, power elements, functions, parameters, components, elements, etc. other than those described throughout the examples of the present disclosure in association with  FIGS. 1-25B . 
     As shown at  2502  in  FIG. 26 , in some examples one aspect of a method  2500  comprises fully implanting a microstimulator via single incision. As shown at  2504  in  FIG. 26 , in some examples one aspect of a method  2500  comprises encapsulating a microstimulator in a non-conductive portion of a housing. As shown at  2506  in  FIG. 26 , in some examples one aspect of a method  2500  comprises arranging at least one partially flexible element to extend from a housing. As shown at  2508  in  FIG. 26 , in some examples one aspect of a method  2500  comprises arranging the at least one partially flexible element to include a nerve-engaging element. As shown at  2510  in  FIG. 26 , in some examples one aspect of a method  2500  comprises arranging the housing to include a nerve-engaging portion. As shown at  2512  in  FIG. 26 , in some examples one aspect of a method  2500  comprises arranging at least one electrode on at least one of a housing and an at least partially flexible nerve-engaging element extending from the housing. 
     In some examples, the various aspects  2502 - 2512  may be performed together or in various combinations, with it being understood that any methods performed according to examples of the present disclosure are not limited to the aspects  2502 - 2512  associated with the method(s) implementable as schematically represented via  FIG. 26 . 
       FIG. 27  is a block diagram schematically representing aspects of a method  2600  of microstimulation, according to one example of the present disclosure. In some examples, at least some aspects of method  2600  may be implemented via at least some of the systems, apparatuses, devices, stimulators (including microstimulators), sensors, power elements, functions, parameters, components, elements, etc. as described throughout the examples of the present disclosure in association with  FIGS. 1-25B . In some examples, at least some aspects of method  2600  may be implemented via at least some systems, apparatuses, devices, stimulators (including microstimulators), sensors, power elements, functions, parameters, components, elements, etc. other than those described throughout the examples of the present disclosure in association with  FIGS. 1-25B . 
     As shown at  2602  in  FIG. 27 , in some examples one aspect of a method  2600  comprises arranging a first portion of a power element to be implantable and to be rechargeable. As shown at  2604  in  FIG. 27 , in some examples one aspect of a method  2600  comprises arranging a second portion of the power element to be external to the patient and to selectively recharge the first portion. As shown at  2606  in  FIG. 27 , in some examples one aspect of a method  2600  comprises arranging the second portion as a charging station comprising at least one of an inductive-based station and a radiofrequency-based station. As shown at  2608  in  FIG. 27 , in some examples one aspect of a method  2600  comprises arranging the charging station as a patient support. As shown at  2610  in  FIG. 27 , in some examples one aspect of a method  2600  comprises arranging the patient support to include at least one sensor for physiologic and/or patient-related environmental information. 
     In some examples, the various aspects  2502 - 2512  may be performed together or in various combinations, with it being understood that any methods performed according to examples of the present disclosure are not limited to the aspects  2502 - 2512  associated with the method(s) implementable as schematically represented via  FIG. 26 . 
     Although specific examples have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific examples shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific examples discussed herein.