Patent Publication Number: US-2016243352-A1

Title: Systems and methods for electrode assemblies

Description:
FIELD OF THE DISCLOSURE 
     The present disclosure relates generally to electrode assemblies, and more particularly, to electrode assemblies for use in neurostimulation systems. 
     BACKGROUND ART 
     Neurostimulation is a treatment method utilized for managing the disabilities associated with pain, movement disorders such as Parkinson&#39;s Disease (PD), dystonia, and essential tremor, and also a number of psychological disorders such as depression, mood, anxiety, addiction, and obsessive compulsive disorders. Deep brain stimulation systems are neurostimulation systems that deliver stimulation to a patient&#39;s brain. 
     Neurostimulation systems generally include leads having one or more electrodes. To control those electrodes, wires or cables are electrically coupled to the electrodes. In at least some known systems, wires or cables are electrically coupled to the electrodes using blind resistance or laser welds. However, such welds may be difficult to form, and may be relatively difficult to inspect, as the formed welds are not readily visible. In other known systems, the wire or cable may be crimped under the electrode. However, this is relatively difficult to implement due to the amount of space required for both creating and positioning the crimp. 
     BRIEF SUMMARY OF THE DISCLOSURE 
     In one embodiment, the present disclosure is directed to an electrode assembly. The electrode assembly includes a wire and a substantially cylindrical electrode including a radially inner surface, a radially outer surface, and a strip defined by at least one slot extending from the radially inner surface to the radially outer surface, wherein the wire is welded to the radially outer surface of the strip. 
     In another embodiment, the present disclosure is directed to a neurostimulation system. The neurostimulation system includes an implantable pulse generator, a substantially cylindrical electrode including a radially inner surface, a radially outer surface, and a strip defined by at least one slot extending from the radially inner surface to the radially outer surface, and a wire electrically coupling the implantable pulse generator to the electrode, wherein the wire is welded to the radially outer surface of the strip. 
     In another embodiment, the present disclosure is directed to a method of assembling an electrode assembly. The method includes threading a wire through at least one slot defined in a substantially cylindrical electrode that includes a radially inner surface, a radially outer surface, and a strip defined by the at least one slot extending from the radially inner surface to the radially outer surface, and welding the wire to the radially outer surface of the strip. 
     The foregoing and other aspects, features, details, utilities and advantages of the present disclosure will be apparent from reading the following description and claims, and from reviewing the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of one embodiment of a stimulation system. 
         FIGS. 2A-2C  are schematic views of stimulation portions that may be used with stimulation system of  FIG. 1 . 
         FIG. 3  is a perspective view of one embodiment of an electrode assembly that may be used with the stimulation system of  FIG. 1 . 
         FIG. 4  is a perspective view illustrating forming a weld in the electrode assembly of  FIG. 3 . 
         FIG. 5  is a perspective view of an alternative electrode assembly that may be used with the stimulation system of  FIG. 1 . 
         FIG. 6  is a perspective view of an alternative electrode assembly that may be used with the stimulation system of  FIG. 1 . 
         FIG. 7  is a perspective view of an alternative electrode assembly that may be used with the stimulation system of  FIG. 1 . 
         FIG. 8  is a perspective view of an alternative electrode assembly that may be used with the stimulation system of  FIG. 1 . 
         FIG. 9  is a perspective view of one embodiment of an electrode formed using a progressive die. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     The present disclosure provides electrode assemblies. An electrode assembly includes a wire and a substantially cylindrical electrode including a radially inner surface, a radially outer surface, and a strip defined by at least one slot extending from the radially inner surface to the radially outer surface, wherein the wire is welded to the radially outer surface of the strip. Although the embodiments described herein are generally described in connection with neurostimulation systems, those of skill in the art will appreciate that the electrode assemblies described herein may be utilized in a variety of fields/applications. 
     Neurostimulation systems are devices that generate electrical pulses and deliver the pulses to nerve tissue of a patient to treat a variety of disorders. Spinal cord stimulation (SCS) is the most common type of neurostimulation within the broader field of neuromodulation. Deep brain stimulation (DBS) is another type of neurostimulation. In SCS, electrical pulses are delivered to nerve tissue in the spine typically for the purpose of chronic pain control. While a precise understanding of the interaction between the applied electrical energy and the nervous tissue is not fully appreciated, it is known that application of an electrical field to spinal nervous tissue can effectively mask certain types of pain transmitted from regions of the body associated with the stimulated nerve tissue. Specifically, applying electrical energy to the spinal cord associated with regions of the body afflicted with chronic pain can induce “paresthesia” (a subjective sensation of numbness or tingling) in the afflicted bodily regions. Thereby, paresthesia can effectively mask the transmission of non-acute pain sensations to the brain. SCS systems generally include a pulse generator and one or more leads. A stimulation lead includes a lead body of insulative material that encloses wire conductors. The distal end of the stimulation lead includes multiple electrodes that are electrically coupled to the wire conductors. The proximal end of the lead body includes multiple terminals (also electrically coupled to the wire conductors) that are adapted to receive electrical pulses. The distal end of a respective stimulation lead is implanted within the epidural space to deliver the electrical pulses to the appropriate nerve tissue within the spinal cord that corresponds to the dermatome(s) in which the patient experiences chronic pain. The stimulation leads are then tunneled to another location within the patient&#39;s body to be electrically connected with a pulse generator or, alternatively, to an “extension.” 
     The pulse generator is typically implanted within a subcutaneous pocket created during the implantation procedure. In SCS, the subcutaneous pocket is typically disposed in a lower back region, although subclavicular implantations and lower abdominal implantations are commonly employed for other types of neuromodulation therapies. 
     Peripheral nerve field stimulation (PNFS) is another form of neuromodulation. The basic devices employed for PNFS are similar to the devices employed for SCS including pulse generators and stimulation leads. In PNFS, the stimulation leads are placed in subcutaneous tissue (hypodermis) in the area in which the patient experiences pain. Electrical stimulation is applied to nerve fibers in the painful area. PNFS has been suggested as a therapy for a variety of conditions such as migraine, occipital neuralgia, trigeminal neuralgia, lower back pain, chronic abdominal pain, chronic pain in the extremities, and other conditions. 
     Referring now to the drawings and in particular to  FIG. 1 , a stimulation system is indicated generally at  100 . Stimulation system  100  generates electrical pulses for application to tissue of a patient, or subject, according to one embodiment. System  100  includes an implantable pulse generator (IPG)  150  that is adapted to generate electrical pulses for application to tissue of a patient. Implantable pulse generator  150  typically includes a metallic housing that encloses a controller  151 , pulse generating circuitry  152 , a battery  153 , far-field and/or near field communication circuitry  154 , and other appropriate circuitry and components of the device. Controller  151  typically includes a microcontroller or other suitable processor for controlling the various other components of the device. Software code is typically stored in memory of pulse generator  150  for execution by the microcontroller or processor to control the various components of the device. 
     Pulse generator  150  may comprise one or more attached extension components  170  or be connected to one or more separate extension components  170 . Alternatively, one or more stimulation leads  110  may be connected directly to pulse generator  150 . Within pulse generator  150 , electrical pulses are generated by pulse generating circuitry  152  and are provided to switching circuitry. The switching circuit connects to output wires, traces, lines, or the like (not shown) which are, in turn, electrically coupled to internal conductive wires (not shown) of a lead body  172  of extension component  170 . The conductive wires, in turn, are electrically coupled to electrical connectors (e.g., “Bal-Seal” connectors) within connector portion  171  of extension component  170 . The terminals of one or more stimulation leads  110  are inserted within connector portion  171  for electrical connection with respective connectors. Thereby, the pulses originating from pulse generator  150  and conducted through the conductors of lead body  172  are provided to stimulation lead  110 . The pulses are then conducted through the conductors of lead  110  and applied to tissue of a patient via electrodes  111 . Any suitable known or later developed design may be employed for connector portion  171 . 
     For implementation of the components within pulse generator  150 , a processor and associated charge control circuitry for an implantable pulse generator is described in U.S. Pat. No. 7,571,007, entitled “SYSTEMS AND METHODS FOR USE IN PULSE GENERATION,” which is incorporated herein by reference. Circuitry for recharging a rechargeable battery of an implantable pulse generator using inductive coupling and external charging circuits are described in U.S. Pat. No. 7,212,110, entitled “IMPLANTABLE DEVICE AND SYSTEM FOR WIRELESS COMMUNICATION,” which is incorporated herein by reference. 
     An example and discussion of “constant current” pulse generating circuitry is provided in U.S. Patent Publication No. 2006/0170486 entitled “PULSE GENERATOR HAVING AN EFFICIENT FRACTIONAL VOLTAGE CONVERTER AND METHOD OF USE,” which is incorporated herein by reference. One or multiple sets of such circuitry may be provided within pulse generator  150 . Different pulses on different electrodes may be generated using a single set of pulse generating circuitry using consecutively generated pulses according to a “multi-stimset program” as is known in the art. Alternatively, multiple sets of such circuitry may be employed to provide pulse patterns that include simultaneously generated and delivered stimulation pulses through various electrodes of one or more stimulation leads as is also known in the art. Various sets of parameters may define the pulse characteristics and pulse timing for the pulses applied to various electrodes as is known in the art. Although constant current pulse generating circuitry is contemplated for some embodiments, any other suitable type of pulse generating circuitry may be employed such as constant voltage pulse generating circuitry. 
     Stimulation lead(s)  110  may include a lead body of insulative material about a plurality of conductors within the material that extend from a proximal end of lead  110  to its distal end. The conductors electrically couple a plurality of electrodes  111  to a plurality of terminals (not shown) of lead  110 . The terminals are adapted to receive electrical pulses and the electrodes  111  are adapted to apply stimulation pulses to tissue of the patient. Also, sensing of physiological signals may occur through electrodes  111 , the conductors, and the terminals. Additionally or alternatively, various sensors (not shown) may be located near the distal end of stimulation lead  110  and electrically coupled to terminals through conductors within the lead body  172 . Stimulation lead  110  may include any suitable number of electrodes  111 , terminals, and internal conductors. 
       FIGS. 2A-2C  respectively depict stimulation portions  200 ,  225 , and  250  for inclusion at the distal end of lead  110 . Stimulation portion  200  depicts a conventional stimulation portion of a “percutaneous” lead with multiple ring electrodes. Stimulation portion  225  depicts a stimulation portion including several “segmented electrodes.” The term “segmented electrode” is distinguishable from the term “ring electrode.” As used herein, the term “segmented electrode” refers to an electrode of a group of electrodes that are positioned at the same longitudinal location along the longitudinal axis of a lead and that are angularly positioned about the longitudinal axis so they do not overlap and are electrically isolated from one another. Example fabrication processes are disclosed in U.S. Patent Publication No. 2011/0072657, entitled, “METHOD OF FABRICATING STIMULATION LEAD FOR APPLYING ELECTRICAL STIMULATION TO TISSUE OF A PATIENT,” which is incorporated herein by reference. Stimulation portion  250  includes multiple planar electrodes on a paddle structure. 
     Controller device  160  may be implemented to recharge battery  153  of pulse generator  150  (although a separate recharging device could alternatively be employed). A “wand”  165  may be electrically connected to controller device through suitable electrical connectors (not shown). The electrical connectors are electrically connected to coil  166  (the “primary” coil) at the distal end of wand  165  through respective wires (not shown). Typically, coil  166  is connected to the wires through capacitors (not shown). Also, in some embodiments, wand  165  may comprise one or more temperature sensors for use during charging operations. 
     The patient then places the primary coil  166  against the patient&#39;s body immediately above the secondary coil (not shown), i.e., the coil of the implantable medical device. Preferably, the primary coil  166  and the secondary coil are aligned in a coaxial manner by the patient for efficiency of the coupling between the primary and secondary coils. Controller  160  generates an AC-signal to drive current through coil  166  of wand  165 . Assuming that primary coil  166  and secondary coil are suitably positioned relative to each other, the secondary coil is disposed within the field generated by the current driven through primary coil  166 . Current is then induced in secondary coil. The current induced in the coil of the implantable pulse generator is rectified and regulated to recharge battery of generator  150 . The charging circuitry may also communicate status messages to controller  160  during charging operations using pulse-loading or any other suitable technique. For example, controller  160  may communicate the coupling status, charging status, charge completion status, etc. 
     External controller device  160  is also a device that permits the operations of pulse generator  150  to be controlled by user after pulse generator  150  is implanted within a patient, although in alternative embodiments separate devices are employed for charging and programming. Also, multiple controller devices may be provided for different types of users (e.g., the patient or a clinician). Controller device  160  can be implemented by utilizing a suitable handheld processor-based system that possesses wireless communication capabilities. Software is typically stored in memory of controller device  160  to control the various operations of controller device  160 . Also, the wireless communication functionality of controller device  160  can be integrated within the handheld device package or provided as a separate attachable device. The interface functionality of controller device  160  is implemented using suitable software code for interacting with the user and using the wireless communication capabilities to conduct communications with IPG  150 . 
     Controller device  160  preferably provides one or more user interfaces to allow the user to operate pulse generator  150  according to one or more stimulation programs to treat the patient&#39;s disorder(s). Each stimulation program may include one or more sets of stimulation parameters including pulse amplitude, pulse width, pulse frequency or inter-pulse period, pulse repetition parameter (e.g., number of times for a given pulse to be repeated for respective stimset during execution of program), etc. IPG  150  modifies its internal parameters in response to the control signals from controller device  160  to vary the stimulation characteristics of stimulation pulses transmitted through stimulation lead  110  to the tissue of the patient. Neurostimulation systems, stimsets, and multi-stimset programs are discussed in PCT Publication No. WO 2001/93953, entitled “NEUROMODULATION THERAPY SYSTEM,” and U.S. Pat. No. 7,228,179, entitled “METHOD AND APPARATUS FOR PROVIDING COMPLEX TISSUE STIMULATION PATTERNS,” which are incorporated herein by reference. 
     Example commercially available neurostimulation systems include the EON MINI™ pulse generator and RAPID PROGRAMMER™ device from St. Jude Medical, Inc. (Plano, Tex.). Example commercially available stimulation leads include the QUATTRODE™, OCTRODE™, AXXESS™ LAMITRODE™, TRIPOLE™, EXCLAIM™, and PENTA™ stimulation leads from St. Jude Medical, Inc. 
     In  FIG. 3 , an electrode assembly is indicated generally at  300 . Electrode assembly  300  may be used, for example, in stimulation portions  200 ,  225 , and/or  250 . As shown in  FIG. 3 , electrode assembly  300  includes a substantially cylindrical electrode  302  and cabling  303 . Electrode  302  may be, for example, less than 2 millimeters (mm) in diameter. Cabling  303  includes an inner tubing  304  and a plurality of cables  305  each including a wire and associated insulation. A wire  306  included in cables  305  electrically couples to electrode  302 , as described herein. Signals sent between electrode  302  and a device (e.g., pulse generator  150 ) via wire  306  facilitate controlling electrically stimulation delivered by electrode  302  and/or recording measurements (e.g., voltage measurements) measured at electrode  302 . 
     Electrode  302  has a radially inner surface  310  and a radially outer surface  312 . In this embodiment, two slots  314  are formed in electrode  302 , extending from radially inner surface  310  to radially outer surface  312 . Slots  314  define a strip  320  therebetween. In this embodiment, strip  320  includes a substantially planar portion  322 . Alternatively, strip  320  may have any shape and/or configuration that enables electrode assembly  300  to function as described herein. 
     To electrically coupled wire  306  to electrode  302 , a weld  330  is formed between electrode  302  and wire  306  on strip  320 . Notably, weld  330  is formed on radially outer surface  312  of strip  320 . Specifically, as shown in  FIG. 3 , wire  306  is threaded through slots  314  such that wire  306  is above (i.e., radially outward of) strip  320  but below (i.e., radially inward of) the remainder of electrode  302 . Welding wire  306  to radially outer surface  312  provides several advantages. For example, once formed, weld  330  is readily visible for inspection purposes. Further, weld  330  is easier to form on radially outer surface  312  than radially inner surface  310 . 
     For example,  FIG. 4  illustrates forming weld  330  using a resistance weld tool  402 . Alternatively, weld  330  may be formed using laser welding or any other suitable welding technique (e.g., arc welding, gas welding, electron beam welding, or solid-state welding). As shown in  4 , as wire  306  is welded to radially outer surface  312 , the location of weld  330  is readily accessible to resistance weld tool  402 . In contrast, if wire  306  were welded to radially inner surface  310 , it would be relatively difficult, if not impossible, to position resistance weld tool  402  properly for the welding. Once weld  330  is formed, to secure wire  306 , at least a portion of electrode assembly  300  is back-filled with a polymer using a reflow or injection molding process. 
       FIG. 5  is a perspective view of an alternative electrode assembly  500 . Unless otherwise indicated, electrode assembly  500  is substantially similar to electrode assembly  300 . In contrast to strip  320  of electrode assembly  300 , a strip  520  of electrode  502  of assembly  500  does not include a substantially planar portion. Instead, strip  520  includes a first curved portion  522  and a second curved portion  524  that bend towards each other to meet at a midpoint  526  of strip  520 . In this embodiment, wire  306  is welded to strip  520  proximate midpoint  526 . 
       FIG. 6  is a perspective view of another alternative electrode assembly  600 . Unless otherwise indicated, electrode assembly  600  is substantially similar to electrode assembly  300 . In contrast to electrode assembly  300 , in electrode assembly  600 , wire  306  is not welded directly to a strip  620  of an electrode  602 . Instead a conductive tubing  630  is crimped onto wire  306 , and the combined conductive tubing  630  and wire  306  are welded onto electrode  602 . In this embodiment, wire  306  still includes insulation. However, the heat from the weld destroys/flows the cable insulation to create the electrical connection. In other embodiments, the bare wire (i.e., without insulation) may be welded directly onto electrode  602 . In the embodiment shown in  FIG. 6 , a planar portion  622  of strip  620  is radially recessed relative to the rest of electrode  602 . 
       FIG. 7  is a perspective view of yet another alternative electrode assembly  700 . Unless otherwise indicated, electrode assembly  700  is substantially similar to electrode assembly  300 . In contrast to electrode assembly  300 , a strip  720  is located at an end  722  of an electrode  702  such that electrode  702  includes only a single slot  714 . Slot  714  may have a width of, for example, two thousandths of an inch. In the configuration of electrode assembly  700 , it may be easier to position wire  306 , as wire  306  need only be threaded through one slot  714 , instead of multiple slots  314 . Further, strip  720  may provide more surface area than in embodiments including multiple slots. 
       FIG. 8  is a perspective view of another alternative electrode assembly  800 . Unless otherwise indicated, electrode assembly  800  is substantially similar to electrode assembly  700 . Conductive tubing  630  is shown in  FIG. 8  (and may also be used with electrode assembly  700 ) on a strip  820  of an electrode  802 . In contrast to strip  720 , strip  820  includes a first crimped feature  822 , a second crimped feature  824 , and a substantially planar portion  826  extending between first and second crimped features  822  and  824 . Crimped features  822  and  824  facilitate improving a structural integrity of strip  820 . 
     The electrodes described herein (e.g., electrodes  302 ,  502 ,  602 ,  702 , and  802 ) may be fabricated using any suitable methods. For examples, the electrodes may be fabricated using a progressive die or a deep drawing technique.  FIG. 9  is a perspective view of an electrode  902  formed using a progressive die. As shown in  FIG. 9 , for electrode  902 , a strip  920  is formed by a first segment  922  and a second segment  924  extending towards one another and separated by a slit  926 . 
     Although certain embodiments of this disclosure have been described above with a certain degree of particularity, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this disclosure. All directional references (e.g., upper, lower, upward, downward, left, right, leftward, rightward, top, bottom, above, below, vertical, horizontal, clockwise, and counterclockwise) are only used for identification purposes to aid the reader&#39;s understanding of the present disclosure, and do not create limitations, particularly as to the position, orientation, or use of the disclosure. Joinder references (e.g., attached, coupled, connected, and the like) are to be construed broadly and may include intermediate members between a connection of elements and relative movement between elements. As such, joinder references do not necessarily infer that two elements are directly connected and in fixed relation to each other. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. Changes in detail or structure may be made without departing from the spirit of the disclosure as defined in the appended claims. 
     When introducing elements of the present disclosure or the preferred embodiment(s) thereof, the articles “a”, “an”, “the”, and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including”, and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. 
     As various changes could be made in the above constructions without departing from the scope of the disclosure, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.