Abstract:
In an embodiment, a neurostimulator system includes a pulse generator module and a power source and control module. The pulse generator module includes an electrical stimulation lead and electrodes and is configured to be implanted within a body of a subject, to provide a therapy to the subject, and to receive power wirelessly from a source remote from the pulse generator module. And the power source and control module is configured to be located external to the body of the subject, to cause the pulse generator module to affect the therapy, and to provide power wirelessly to the pulse generator module.

Description:
PRIORITY CLAIM 
     The present application is a continuation-in-part of the U.S. patent application Ser. No. 13/796,636, filed Mar. 12, 2013, and now U.S. Pat. No. 8,948,880 issued Feb. 3, 2015; which application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/611,419 filed Mar. 15, 2012; all of the foregoing applications are incorporated herein by reference in their entireties. 
    
    
     BACKGROUND 
     An embodiment of the present invention generally relates to a lead for use in an implantable therapy system. The present invention more particularly relates to a stimulator lead having an integrated switching circuit and optionally also having an integrated pulse generator for efficiently providing an array of electrodes with stimulation energy from an implantable pulse generator. 
     Implantable therapy delivery systems have been in the art and in commercial use for decades. Such systems include cardiac rhythm management systems such pacemakers and defibrillators, nerve stimulators, and even drug delivery systems. 
     Such therapy systems, and especially in the case of cardiac rhythm management and nerve stimulator systems, include an implantable device that includes a power source, such as a battery and electronic circuitry that generates therapy stimulation pulses and controls when the therapy stimulation pulses are delivered. To actually deliver the stimulation pulses, the systems also generally include multiple stimulation electrodes on the surface of a lead that make electrical contact with the desired (target) tissue and a lead system, including one or more leads that connect the electrodes to the electronic circuitry in the device. 
     As implantable therapy device design has progressed over time, more and more functionality has been incorporated into the implantable devices and more and more electrodes have been similarly required to shape stimulation at the target tissue volume to enable that functionality. For example, implantable therapy devices usually now incorporate microcontrollers that are capable of controlling multiple therapy delivery modalities in multiple locations of the body. Those modalities may include both stimulation pulse delivery to selected tissue(s) and/or physiologic activity monitoring and data gathering for analysis and adjustment of therapy. In the case of nerve stimulation systems, these systems now find use in various locations of the body as for example, in brain tissue stimulation and spinal nerve stimulation. 
     Particularly in nerve stimulators, there has been an increase in the number of electrodes assigned to shape and deliver electrical pulses to a given anatomical region. The intended advantage is to obtain stimulation selectivity and directionality and to shape current delivery to a volume of tissue. Today, a system may incorporate as many as sixteen to twenty electrodes in a given area. Unfortunately, current state of the art connectivity measures to connect the electrodes back to the implantable pulse generation devices have limited the number and utility of electrodes. 
     For example, each electrode requires an electrical conductor or wire to extend from the electrode through its associated lead and back to the implanted device. The large number of such conductors is limited by the amount of space available in a lead. Further, each conductor requires a hermetically sealed connection with the implanted device. This places a huge burden on feed-through systems which can accommodate only a limited number required contacts and in effect, limits the number of electrodes to the constraints imposed by the connector. 
     Standard technology includes conductor wire for lead catheters, toroidal spring connectors between the lead and the implantable pulse generator devices, and a hermetic feed-through constructed from metal pins and ceramic insulators. Alternative designs could include improvement to the technology for these methods of connecting the lead to the implantable pulse generator device, by providing higher density connections through miniaturization. Higher density electrodes may now be designed through the use of thin film deposition technology to establish higher density electrodes as well as the high density interconnect conductors. 
     Still further, the required higher density of conductors required for the increased number of electrodes results in smaller diameter conductors. The smaller diameter conductors present higher impedance conduction paths between the electrodes and the implantable devices. This results in higher required power output from the implantable electronic devices to deliver the desired effective stimulation therapy. The required higher power output also either decreases battery life of the implantable devices or requires larger batteries to be employed. The smaller diameter conductor wire would also exhibit reduced strength and flex life in locations where this results in reduced reliability of the cable lead. Such stresses at the lead/stimulator connections cause an unacceptably high rate of device failure. 
     As may be seen from the foregoing, there is a need in the art for a different approach in providing therapy within a body where electric therapy is delivered from an implantable pulse generator device to a high density of electrodes. It would be desirable if such an approach would avoid high impedance conduction paths, minimize electrode dislodgement, prevent interconnection issues and increase the safety to and convenience of the patient. The present invention addresses these and other issues. 
     SUMMARY 
     According to an embodiment, a neurostimulator system includes a pulse generator module and a power source and control module. The pulse generator module includes an electrical stimulation lead and electrodes and is configured to be implanted within a body of a subject, to provide a therapy to the subject, and to receive power wirelessly from a source remote from the pulse generator module. And the power source and control module is configured to be located external to the body of the subject, to cause the pulse generator module to effect the therapy, and to provide power wirelessly to the pulse generator module. 
     According to one embodiment, a stimulation lead for connecting a pulse generator having a plurality of outputs to electrodes of an electrode array includes a flexible body and the electrode array. The electrode array is distal to the flexible body and the flexible body has a proximal portion and an interface portion. The lead further includes a plurality of conductors extending through the proximal portion to the interface portion, a connector arranged to connect a proximal end of each one of the conductors to a respective given one of the outputs, and a selection circuit within the interface portion. The selection circuit has a plurality of inputs. Each input of the selection circuit is connected to a distal end of a respective given one of the conductors. The selection circuit further has a plurality of outputs. Each output of the selection circuit is coupled to a respective one of the electrodes of the electrode array. The plurality of outputs of the selection circuit are greater in number than the plurality of outputs of the pulse generator. A power supply is configured to receive input power wirelessly from an external source, to generate from the input power at least one power supply signal, and to provide the at least one power supply signal to at least the pulse generator and the selection circuit. 
     The electrode array may include a flexible substrate and the electrodes of the electrode array may be distributed and carried on the flexible substrate. The flexible substrate may be configured as a cylinder. The electrode array may include a flexible cylindrical carrier, and the flexible substrate may be wrapped about the flexible cylindrical carrier. The flexible cylindrical carrier may be formed of silicone. The flexible substrate may be substantially planar and have a paddle configuration. 
     The electrode array may include a backing layer arranged in a corkscrew configuration and the flexible substrate may be carried on the backing layer within the corkscrew configuration. 
     The selection circuit may include a switching array. The switching array may comprise an integrated circuit. 
     In another embodiment, a universal stimulation lead module for connecting a pulse generator having a plurality of outputs to electrodes of an electrode array includes a flexible body having a proximal portion and a distal interface portion, a plurality of conductors extending through the proximal portion to the interface portion, a connector arranged to connect a proximal end of each one of the conductors to a respective given one of the outputs, and a selection circuit within the interface portion. The selection circuit has a plurality of inputs, each input of the selection circuit being connected to a distal end of a respective given one of the conductors. The selection circuit further has a plurality of outputs, each output of the selection circuit being arranged to be coupled to a respective one of the electrodes of the electrode array. The plurality of outputs of the selection circuit are greater in number than the plurality of outputs of the pulse generator. A power supply is configured to receive input power wirelessly from an external source, to generate output power from the input power, and to provide the output power to at least the pulse generator and the selection circuit. 
     The selection circuit may include a switching array. The switching array may comprise an integrated circuit. 
     In another embodiment, a stimulation lead provides stimulation energy to selected ones of a plurality of electrodes of an electrode array under control of a control device having a plurality of outputs that provide power and control signals. The stimulation lead includes a flexible body and the electrode array. The electrode array is distal to the flexible body. The flexible body has a proximal portion and an interface portion. The lead further includes a plurality of conductors extending through the proximal portion to the interface portion, a connector arranged to connect a proximal end of each one of the conductors to a respective given one of the outputs and a pulse generator within the interface portion. The pulse generator is responsive to the power and control signals of the control device to generate the stimulation energy. The lead further includes a selection circuit also within the interface portion. The selection circuit is coupled to the pulse generator and further has a plurality of outputs. Each output of the selection circuit is coupled to a respective one of the electrodes of the electrode array. The selection circuit is arranged to provide selected ones of the electrodes with the stimulation energy responsive to the control signals from the control device. The plurality of outputs of the selection circuit are greater in number than the plurality of outputs of the control device. 
     The electrode array may include a flexible substrate and the electrodes of the electrode array may be distributed and carried on the flexible substrate. The flexible substrate may be configured as a cylinder. The electrode array may include a flexible cylindrical carrier, and the flexible substrate may be wrapped about the flexible cylindrical carrier. The flexible cylindrical carrier may be formed of silicone. The flexible substrate may be substantially planar and have a paddle configuration. 
     The electrode array may include a backing layer arranged in a corkscrew configuration. The flexible substrate may be carried on the backing layer within the corkscrew configuration. 
     The selection circuit may include a switching array. The switching array may comprise an integrated circuit. The pulse generator comprises an integrated circuit. 
     In still another embodiment a universal stimulation lead module provides stimulation energy to selected ones of a plurality of electrodes of an electrode array under control of a control device having a plurality of outputs that provide power and control signals. The lead module includes a flexible body having a proximal portion and a distal interface portion, a plurality of conductors extending through the proximal portion to the interface portion, a connector arranged to connect a proximal end of each one of the conductors to a respective given one of the outputs of the control device and a pulse generator within the interface portion. The pulse generator is response to the power and controls signals from the control device to generate the stimulation energy. The selection circuit is also within the interface portion and is coupled to the pulse generator. The selection circuit has a plurality of outputs, each output of the selection circuit being coupled to a respective one of the electrodes of the electrode array. The selection circuit is arranged to provide selected ones of the electrodes with the stimulation energy responsive to the control signals from the control device. The plurality of outputs of the selection circuit are greater in number than the plurality of outputs of the control device. 
     The selection circuit may include a switching array. The switching array may comprise an integrated circuit. The pulse generator comprises an integrated circuit. 
     An another embodiment of the implanted neurostimulator is a system which provides power, such as continuous power, from an externally worn device. The power is electromagnetically transferred inductively through coils to provide continuous power to the implanted device. This may replace the need for a rechargeable implanted power source, or may provide another power-source option. The implanted pulse generator is still integrated with the lead for more efficient energy delivery to the electrodes. Wireless communications may be implemented with either near field electromagnetic energy or with RF far field power such as MICS (Medical Implantable Communications Service) methods. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
       The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with further features and advantages thereof, may best be understood by making reference to the following description taken in conjunction with the accompanying drawings, in the several figures of which like reference numerals identify identical elements, and wherein: 
         FIG. 1  is a top view of a stimulation lead according to one embodiment of the invention; 
         FIG. 2  is a top view of another stimulation lead according to another embodiment of the invention; 
         FIG. 3  is a top view of a further stimulation lead according to a further embodiment of the invention; 
         FIG. 4  is a perspective view of the electrode array of the stimulation lead of  FIG. 3  according to an embodiment of the invention; 
         FIG. 5  is a top view of a universal stimulation lead module according to an embodiment of the invention; 
         FIG. 6  is a sectional view of the interface portion of the universal stimulation lead module of  FIG. 5 ; 
         FIG. 7  is a circuit diagram of an alternative lead embodiment wherein the pulse generator is located on the stimulation lead according to another embodiment of the invention; 
         FIG. 8  is a top view of a stimulation lead wherein the pulse generator is located on the stimulation lead according to a further embodiment of the invention; 
         FIG. 9  is a sectional view, to an enlarged scale, of the electronics module of the stimulation lead of  FIG. 8 ; 
         FIG. 10  is a top view, to an enlarged scale, of the electronics module of the stimulation lead of  FIG. 8 ; and 
         FIG. 11  is a top view of another stimulation lead wherein the pulse generator is located on the stimulation lead according to a further embodiment of the invention; 
         FIG. 12  is a circuit diagram of another embodiment wherein the controller and power source are external to the human body and the pulse generator is located on the stimulation lead according to another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIG. 1 , it is a top view of a stimulation lead according to one embodiment of the invention. The stimulation lead  20  of  FIG. 1  is arranged for connecting a pulse generator having a plurality of outputs  21  to electrodes  25  of an electrode array  24 . The stimulation lead  20  generally includes a flexible body  22  and the electrode array  24 . The electrode array  24 , which includes a plurality of electrodes  25 , is distal to the flexible body  22 . The flexible body  22  has a proximal portion  26  and an interface portion  28 . The lead  20  further includes a plurality of conductors  30  extending through the proximal portion  26  to the interface portion  28 . The lead  20  still further includes a connector  32  having contacts  34  associated with each of the pulse generator outputs  21 . The contacts  34  are arranged to connect a proximal end of each one of the conductors  30  to a respective given one of the pulse generator outputs  21 . 
     The lead  20  further includes a selection circuit  36  within the interface portion  28 . The selection circuit  36  preferably includes an integrated switching array  37  of the type known in the art. The selection circuit  36  has a plurality of inputs  38  in the form of connection pads  40 . Each of the connection pads  40  is connected to a distal end of a respective given one of the conductors  30 . The selection circuit  36  further has a plurality of outputs  42 . Each of the outputs  42  of the selection circuit  36  is coupled to a respective one of the electrodes  25  of the electrode array  24  by conductors  46 . As may be noted in  FIG. 1 , the plurality of outputs  42  of the selection circuit are greater in number than the plurality of outputs  21  of the pulse generator. 
     The electrode array  24 , in this embodiment, takes the form of electrodes  25  deposited on a flexible thin film substrate  48 . The thin film substrate  48  is configured as a cylinder by being wrapped around a flexible rod  50  that may be formed from silicone, for example. The wrapping of the thin film electrode array around the silicone flexible rod  50  provides for improved reliability with lead flex and for improved maneuverability. 
       FIG. 2  is a top view of another stimulation lead  60  according to another embodiment of the invention. The lead  60  includes a proximal portion  66  and an interface portion  68  substantially identical to the proximal portion  26  and interface portion  28  of lead  20  of  FIG. 1 . However, here lead  60  includes an electrode array  64  of electrodes  65  deposited on a flexible substrate  78  to form the thin film electrode array  64  in a flat paddle and planar configuration. The electrode array  64  may have a silicone backing  78  to add to directionality, structure, and strength of the thin film electrode array. The paddle electrode configuration could also include a lead introducer catheter, of the type known in the art, to allow the electrode array to be curled up during deployment. Once the catheter is in place, the sheath may be withdrawn allowing the paddle to fold out and be optimally positioned in the desired space. 
       FIG. 3  is a top view of another stimulation lead  80  according to another embodiment of the invention. The lead  80  includes a proximal portion  86  and an interface portion  88  substantially identical to the proximal portion  26  and interface portion  28  of lead  20  of  FIG. 1 . However, as may be best seen in the perspective view of  FIG. 4 , the lead  80  includes an electrode array  84  of electrodes  85  deposited on a flexible substrate  94  that is carried on the inside of a spiraled silicone backing  98  to form the thin film electrode array  84  in a spiral configuration  96 . This allows the cuff of the electrode array  84  to wrap about an individual nerve with the electrode surface facing the nerve. The silicone backing  98  adds to directionality, structure, and strength of the thin film electrode array  96 . 
       FIG. 5  is a top view of a universal stimulation lead module  100  according to an embodiment of the invention. This provides a generic module for a customized electrode array to suit the needs of a specific clinical indication and anatomical site in need of electrical stimulation. More specifically, the universal stimulation lead module  100  of  FIG. 5  may be employed for connecting a pulse generator (not shown) having a plurality of outputs to electrodes of an electrode array. In addition to a customized electrode array, the module  100  may also be used with any one of the electrode arrays disclosed herein. The lead module  100  includes a flexible body  102  having a proximal portion  126  and a distal interface portion  128 . A plurality of conductors  130  extend through the proximal portion  126  to the interface portion  128 . A connector  132  has a plurality of contacts  134 . Each contact  134  is arranged to be connected to a respective given one of the outputs of the pulse generator. The conductors  130 , in turn, connect each respective given one of the contacts  134  to a selection circuit  136  within the interface portion  128 . The selection circuit  136  includes an integrated circuit switching array  137  and has a plurality of inputs  138  in the form of connection pads  140 . Each of the connection pads  140  of the selection circuit  136  is connected to a distal end of a respective given one of the conductors  130 . The selection circuit  136  further has a plurality of outputs  142 . Each output  142  of the selection circuit  136  is arranged to be coupled to a respective one of the electrodes of an electrode array (not shown). The plurality of outputs  142  of the selection circuit  136  are greater in number than the plurality of outputs of the pulse generator and hence the connection contacts  134 . 
       FIG. 6  is a sectional view of the interface portion  128  of the universal stimulation lead module  100  of  FIG. 5 . Here it may be seen that the interface portion  128  includes a plurality of layers  152  of a ceramic substrate  156 . The integrated circuit  137  is electrically connected to the bottom side of the interface portion of the ceramic substrate  156 . A titanium or ceramic lid  158  having a gold brazed flange  154  covers the integrated circuit  137  to provide a hermetically sealed enclosure. On top of the interface portion  128  is a thin film array  141  that includes the outputs  142  ( FIG. 5 ) of the interface portion  128 . Between the layers  152  of the ceramic are formed conductor paths  160  as, for example, path  160  to interconnect the connection pads  140  to the integrated circuit  137 . 
     Both integrated circuit  137  and the thin film array  141  may be designed as a grid array for the interconnection process. The ceramic substrate  152  provides a hermetic interconnect between the integrated circuit  137  and external structures to which it will be electrically connected. Staggering the interconnections within the ceramic substrate  156  ensures a hermetic connection for the electrical connections  160 . 
       FIG. 7  is a circuit diagram of an alternative lead embodiment wherein the pulse generator  180  is located on the stimulation lead according to another embodiment of the invention. Along with the pulse generator  180 , in accordance with this embodiment, a microcontroller  190  and an electrode selection integrated circuit  200  are also on the lead  100 . A more specific example follows with respect to  FIG. 8 . 
     In  FIG. 7  it may be seen that the microcontroller  190  is coupled to both the pulse generator  180  and electrode selection circuit  200 . The microcontroller  180 , responsive to received control signals generated by an implanted power source and control device, determines the parameters of the electrical stimulation provided by the pulse generator  180  and the electrodes to be selected by the electrode selection circuit  200  to which the electrical stimulation is to be applied. In  FIG. 7 , it may be seen that the electrode selection circuit  200  has for example 32 outputs  202  (E 1 -E 32 ) while it has only three power inputs  204 , one communication input  206  and one communication output  208 . Hence with just a few inputs, the lead is able to provide many more electrodes with stimulation. Each of the microcontroller  190 , the pulse generator  180 , and the selection circuit  200  may be a separate integrated circuit or may be integrated into one circuit. 
     Referring now to  FIG. 8 , it is a top view of a stimulation lead  220  wherein the pulse generator  180  is located on the stimulation lead  220  according to a further embodiment of the invention.  FIG. 9  is a sectional view, to an enlarged scale, of the electronics module  228  of the stimulation lead  220  of  FIG. 8  and  FIG. 10  is top view, to an enlarged scale, of the electronics module  228  of the stimulation lead  220  of  FIG. 8 . 
     The stimulation lead  220  of  FIGS. 8-10  provides stimulation energy to selected ones of a plurality of electrodes  225  of an electrode array  224  under control of a control device (not shown) having a plurality of outputs that provide power and control signals. The stimulation lead  220  includes a flexible body  222  and the electrode array  224 . The electrode array  224  is distal to the flexible body  222 . The flexible body  222  has a proximal portion  226  and an interface portion  228 . The lead  220  further includes a plurality of conductors  230  extending through the proximal portion  226  to the interface portion  228 . A connector  242  has a plurality of contacts  234  arranged to connect a proximal end of each one of the conductors  230  to a respective given one of the outputs. The lead  220  further includes the pulse generator  180 , the microcontroller  190 , and the electrode selection circuit  200  within the interface portion. The pulse generator  180  is responsive to the power and control signals of the control device to generate the stimulation energy. The electrode selection circuit  200  is coupled to the pulse generator  180  and further has a plurality of outputs  242 . Each of the outputs  242  of the selection circuit  200  is coupled to a respective one of the electrodes  225  of the electrode array  224 . The electrode selection circuit  200  is arranged to provide selected ones of the electrodes  225  with the stimulation energy responsive to the control signals from the control device. The plurality of outputs  242  of the selection circuit  200  are greater in number than the plurality of outputs of the control device (and thus the number of contacts  234 ). 
     The lead  220  may be fabricated in the same manner as that described with respect to  FIG. 6 . Also, the proximal portion  226  and interface portion  228  may be fabricated without an electrodes array so that together they may form a universal lead module having a pulse generator  180  therein for use with any desired electrode array. Further, as in the previous embodiments, the electrode array  224  may include a flexible substrate  248  and the electrodes  225  of the electrode array  224  may be distributed and carried on the flexible substrate  248 . The flexible substrate  248  may be configured as a cylinder. The electrode array  224  may include a flexible cylindrical carrier  250 , and the flexible substrate  248  may be wrapped about the flexible cylindrical carrier. The flexible cylindrical carrier  250  may be formed of silicone. 
     The electrode array  224  may include a backing layer as shown in the embodiment of  FIGS. 3 and 4  arranged in a corkscrew configuration. The flexible substrate may be carried on the backing layer  98  within the corkscrew configuration. 
       FIG. 11  is a top view of another stimulation lead  260  wherein the pulse generator  180  is located on the stimulation lead  260  according to a further embodiment of the invention. Here, both the pulse generator  180  and microcontroller  190  are integrated into a common integrated circuit  270 . As in the previous embodiments, the stimulation lead  260  includes a flexible body  262  and an electrode array  264 . The electrode array  264  is distal to the flexible body  262 . 
     The flexible body  262  has a proximal portion  226  and an interface portion  228 , which portions may be constructed and fabricated as previously described. To that end, the lead further includes a plurality of conductors  280  extending through the proximal portion  266  to the interface portion  268 . A connector  282  has a plurality of contacts  284  arranged to connect a proximal end of each one of the conductors  280  to a respective given one of the outputs of a control device (not shown). The lead  260  further includes the pulse generator  180  and microcontroller  270  and the electrode selection circuit  200  within the interface portion  268 . The pulse generator  180  is responsive to the power and control signals of the control device to generate the stimulation energy. The electrode selection circuit  200  is coupled to the pulse generator  180  and further has a plurality of outputs  242 . Each of the outputs  242  of the electrode selection circuit  200  is coupled to a respective one of the electrodes  275  of the electrode array  264 . The electrode selection circuit  200  is arranged to provide selected ones of the electrodes  275  with the stimulation energy responsive to the control signals from the control device. The plurality of outputs  242  of the electrode selection circuit  200  are greater in number than the plurality of outputs of the control device (and thus the number of contacts  284 ). 
     The lead  260  may be fabricated in the same manner as that described with respect to  FIG. 6 . Also, the proximal portion  266  and interface portion  268  may be fabricated without an electrode array so that together they may form a universal lead module having a pulse generator  180  therein for use with any desired electrode array. Further, as in the previous embodiments, the electrode array  264  may include a flexible substrate  288  and the electrodes  275  of the electrode array  264  may be distributed and carried on the flexible substrate  288 . The flexible substrate  288  may be configured as a cylinder. The electrode array may include a flexible cylindrical carrier  289 , and the flexible substrate  288  may be wrapped about the flexible cylindrical carrier. The flexible cylindrical carrier  289  may be formed of silicone. 
     The electrode array  264  may include a backing layer as shown in the embodiment of  FIGS. 3 and 4  arranged in a corkscrew configuration. The flexible substrate  288  may be carried on the backing layer  98  within the corkscrew configuration. 
       FIG. 12  is a circuit diagram of another embodiment wherein the controller and power source  350  is located external to the body of a subject, such as a human body, according to another embodiment of the invention. 
     In  FIG. 12  it may be seen that a pulse generator module  300  is implanted in the human body. The microcontroller  190  is coupled to both the pulse generator  180  and electrode selection circuit  200 . The microcontroller  180 , responsive to received control signals generated by an implanted power source and control device, determines the parameters of the electrical stimulation provided by the pulse generator  180  and the electrodes to be selected by the electrode selection circuit  200  to which the electrical stimulation is to be applied. In  FIG. 12 , it may be seen that the electrode selection circuit  200  has for example 32 outputs  202  (E 1 -E 32 ) while it has only as few as two power inputs  204  one control input  206  and one control output  208  that extend to outside of the lead (not shown in  FIG. 12 ), into which the electrodes  202  extend. Hence with just a few inputs, the lead is able to provide many more electrodes with stimulation. Each of the microcontroller  190 , the pulse generator  180 , and the selection circuit  200  may be a separate integrated circuit or may be integrated into one circuit. The implanted pulse generator module  300  receives power transcutaneously via inductive coupling from an external controller and power source  350  through electromagnetic coupling between a primary coil  390  and a secondary coil  310 . The power is converted with a power conversion circuit  320  to the required voltages to power the circuits of the implanted pulse generator module  300 . The secondary coil  310  is implanted beneath the subject&#39;s skin  395 . The primary coil  390  transmits power to the secondary coil  310  from the external power source  380  which consists of power conversion circuits, an external battery, and which may be configured to receive power (e.g., to charge the battery or to provide power to the power source  380  directly) from an adapter such as an AC adapter. The microcontroller  360  determines the amount of power to be generated by the power source  380  as provided to the primary coil  390 . The secondary coil  310  provides the received power to a power conversion circuit  320  which converts the power to DC voltages required to power the pulse generator IC  180 , microcontroller  190 , the electrode selection multiplexer circuit  200 , and any other circuits within the module  300 . A supply output capacitor  330  may be large enough to store and provide reserve power for situations of temporary unexpected power interruptions or discontinuities from the external wireless power transfer; alternatively, the module  300  may include a battery that is rechargeable by the power converter  320  and that is configured to provide reserve power for situations of unexpected power interruptions, or that is configured to provide reserve power during a power interruption in response to the capacitor discharging to a level at which it can no longer provide sufficient power to the pulse generator module  300 . The microcontroller  360  also transmits and receives wireless communication to and from the implanted pulse generator module  300 . The wireless communication may be implemented as an RF far field method (e.g., Medical Information Communications Service, MICS protocol) or with near field electromagnetic data transfer. A two way wireless communications occurs between the external RF antenna or coil  370 , and the implanted RF antenna or coil  340 . 
     While particular embodiments of the present invention have been shown and described, modifications may be made, and it is therefore intended in the appended claims to cover all such changes and modifications which fall within the true spirit and scope of the invention as defined by those claims.