Patent Application
20150018913
The present invention is directed to the area of implantable electrical stimulation systems and methods of making and using the systems. The present invention is also directed implantable electrical stimulation leads using superposition signals for delivering neuromodulation signals, as well as methods of making and using the leads and electrical stimulation systems.
Implantable electrical stimulation systems have proven therapeutic in a variety of diseases and disorders. For example, spinal cord stimulation systems have been used as a therapeutic modality for the treatment of chronic pain syndromes. Peripheral nerve stimulation has been used to treat chronic pain syndrome and incontinence, with a number of other applications under investigation. Functional electrical stimulation systems have been applied to restore some functionality to paralyzed extremities in spinal cord injury patients.
Stimulators have been developed to provide therapy for a variety of treatments. A stimulator can include an implantable pulse generator (IPG), one or more leads, and an array of stimulator electrodes on each lead. The stimulator electrodes are in contact with or near the nerves, muscles, or other tissue to be stimulated. The pulse generator generates electrical pulses that are delivered by the electrodes to body tissue.
In one embodiment, an electrical stimulation lead includes at least one lead body having a distal end portion, a proximal end portion, and a longitudinal length; multiple electrodes disposed along the distal end portion of the at least one lead body; and at least one terminal disposed along the proximal end portion of the at least one lead body. The lead has more electrodes than terminals. The lead also includes a signal separator disposed along the lead between the electrodes and the at least one terminal; at least one terminal conductor electrically coupling one of the at least one terminal to the signal separator; and multiple electrode conductors. Each electrode conductor electrically couples the signal separator to a different one of the electrodes. The lead has more electrode conductors than terminal conductors. The signal separator is configured and arranged to receive signals from the at least one terminal conductor and to separate the signals by frequency into electrode signals. Each electrode signal is directed along a pre-determined one of the electrode conductors to a corresponding one of the electrodes based on the frequency of the electrode signal.
In another embodiment, an electrical stimulating system includes the electrical stimulation lead described above; an implantable pulse generator coupleable to the electrical stimulation lead; and a connector for receiving the electrical stimulation lead. The implantable pulse generator includes a housing, and an electronic subassembly disposed in the housing. The connector has a proximal end, a distal end, and a longitudinal length. The connector includes a connector housing defining a port at the distal end of the connector. The port is configured and arranged for receiving the proximal end of the lead body of the electrical stimulation lead. The connector also includes at least one connector contact disposed in the connector housing. The at least one connector contact is configured and arranged to couple to the at least one terminal disposed on the proximal end of the lead body of the electrical stimulation lead.
In yet another embodiment, an electrical stimulating system includes an external signal source configured and arranged to be positioned outside of a patient's body; and an implantable lead. The lead includes at least one lead body having a distal end portion, a proximal end portion, and a longitudinal length; multiple electrodes disposed along the distal end portion of the at least one lead body; a signal separator disposed along the lead; at least one proximal conductor; and multiple electrode conductors. Each proximal conductor electrically couples to the signal separator and is configured and arranged to receive signals transmitted by the external signal source; and each electrode conductor electrically couples the signal separator to a different one of the electrodes. The lead has more electrode conductors than proximal conductors. The signal separator is configured and arranged to receive the signals from the at least one proximal conductor and to separate the signals by frequency into electrode signals. Each electrode signal is directed along a pre-determined one of the electrode conductors to a corresponding one of the electrodes based on the frequency of the electrode signal.
Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following drawings. In the drawings, like reference numerals refer to like parts throughout the various figures unless otherwise specified.
For a better understanding of the present invention, reference will be made to the following Detailed Description, which is to be read in association with the accompanying drawings, wherein:
The present invention is directed to the area of implantable electrical stimulation systems and methods of making and using the systems. The present invention is also directed implantable electrical stimulation leads using superposition signals for delivering neuromodulation signals, as well as methods of making and using the leads and electrical stimulation systems.
Suitable implantable electrical stimulation systems include, but are not limited to, a least one lead with one or more electrodes disposed along a distal end of the lead and one or more terminals disposed along the one or more proximal ends of the lead. Leads include, for example, percutaneous leads, paddle leads, and cuff leads. Examples of electrical stimulation systems with leads are found in, for example, U.S. Pat. Nos. 6,181,969; 6,516,227; 6,609,029; 6,609,032; 6,741,892; 7,949,395; 7,244,150; 7,672,734; 7,761,165; 7,974,706; 8,175,710; 8,224,450; and 8,364,278; and U.S. Patent Application Publication No. 2007/0150036, all of which are incorporated by reference.
In many conventional electrical stimulation leads, a large number of electrical conductors extend along the length of the lead. In some leads, there is a conductor for each of the electrodes at the distal end of the lead. The leads described herein utilize fewer conductors (in some embodiments, only a single conductor) along much of the length of the lead to provide independent signals to multiple electrodes by superposition of the signals and later separation near the electrodes. Utilizing fewer conductors along a portion of the lead can result in that portion having a thinner diameter or cross-section.
It will be understood that the electrical stimulation system can include more, fewer, or different components and can have a variety of different configurations including those configurations disclosed in the electrical stimulation system references cited herein. For example, instead of a paddle body, the electrodes can be disposed in an array at or near the distal end of a lead body forming a percutaneous lead.
The lead 103 can be coupled to the implantable pulse generator 102 in any suitable manner. In
In
The implantable pulse generator 102 typically includes a connector housing 112 and a sealed electronics housing 114. An electronic subassembly 110 and an optional power source 120 are disposed in the electronics housing 114. A connector 144 is disposed in the connector housing 112. The connector 144 is configured and arranged to make an electrical connection between the lead 103 and the electronic subassembly 110 of the implantable pulse generator 102.
The electrical stimulation system or components of the electrical stimulation system, including the paddle body 104, the one or more of the lead bodies 106, and the implantable pulse generator 102, are typically implanted into the body of a patient. The electrical stimulation system can be used for a variety of applications including, but not limited to deep brain stimulation, neural stimulation, spinal cord stimulation, muscle stimulation, and the like.
The electrodes 134 can be formed using any conductive, biocompatible material. Examples of suitable materials include metals, alloys, conductive polymers, conductive carbon, and the like, as well as combinations thereof. In at least some embodiments, one or more of the electrodes 134 are formed from one or more of: platinum, platinum iridium, palladium, palladium rhodium, or titanium.
Any suitable number of electrodes 134 can be disposed on the lead including, for example, four, five, six, seven, eight, nine, ten, eleven, twelve, fourteen, sixteen, twenty-four, thirty-two, or more electrodes 134. In the case of paddle leads, the electrodes 134 can be disposed on the paddle body 104 in any suitable arrangement. In
The electrodes of the paddle body 104 (or one or more lead bodies 106) are typically disposed in, or separated by, a non-conductive, biocompatible material such as, for example, silicone, polyurethane, polyetheretherketone (“PEEK”), epoxy, and the like or combinations thereof. The one or more lead bodies 106 and, if applicable, the paddle body 104 may be formed in the desired shape by any process including, for example, molding (including injection molding), casting, and the like. The non-conductive material typically extends from the distal ends of the one or more lead bodies 106 to the proximal end of each of the one or more lead bodies 106.
In the case of paddle leads, the non-conductive material typically extends from the paddle body 104 to the proximal end of each of the one or more lead bodies 106. Additionally, the non-conductive, biocompatible material of the paddle body 104 and the one or more lead bodies 106 may be the same or different. Moreover, the paddle body 104 and the one or more lead bodies 106 may be a unitary structure or can be formed as two separate structures that are permanently or detachably coupled together.
One or more terminals (e.g., 310 in
The one or more terminal conductors are embedded in the non-conductive material of the lead body 106 or can be disposed in one or more lumens (not shown) extending along the lead body 106. For example, any of the terminal conductors (identified by reference number 452 in
The connector 144 defines at least one port into which a proximal end of the elongated device 300 can be inserted, as shown by directional arrow 312. In
The connector 144 also includes one or more connector contacts, such as connector contact 314, disposed within each port 304. When the elongated device 300 is inserted into the port 304, the connector contact(s) 314 can be aligned with the terminal(s) 310 disposed along the proximal end(s) of the elongated device(s) 300 to electrically couple the implantable pulse generator 102 to the electrodes (134 of
A lead extension connector 322 is disposed on the lead extension 324. In
In at least some embodiments, the proximal end of the lead extension 324 is similarly configured and arranged as a proximal end of the lead 103 (or other elongated device 300). The lead extension 324 may include one or more electrically conductive wires (not shown) that electrically couple the connector contact(s) 340 to a proximal end 348 of the lead extension 324 that is opposite to the distal end 326. The conductive wire(s) disposed in the lead extension 324 can be electrically coupled to one or more terminals (not shown) disposed along the proximal end 348 of the lead extension 324. The proximal end 348 of the lead extension 324 is configured and arranged for insertion into a connector disposed in another lead extension (or another intermediate device). As shown in
Signals to multiple independent electrodes can be directed along a single terminal conductor by superposition (e.g., multiplexing) of the signals. For example, each independent electrode may be associated with a particular frequency or frequency range. Signals for that electrode are generated with that frequency or frequency range and directed along the terminal conductor. Further down the lead (for example, near the distal end of the lead) is a signal separator that separates (e.g., demultiplexes) the signals for the individual electrodes and sends each individual signal along the appropriate electrode conductor to the designated electrode.
The structure and function of IPG 402 can be similar to that of IPG 102. In at least some embodiments, the IPG 402 generates pulses of stimulation energy at a low frequency pulse rate (for example, in a range from 1 Hz to 100 KHz). The IPG 402 is capable of generating such pulses for any of the electrodes. To accomplish the superposition of signals, the energy pulses have an underlying AC signal which has a high frequency (for example, in the 200 KHz to 1 GHz range). The signal for each electrode is associated with a different frequency or frequency range which are spaced apart sufficient to be reliably separated by the signal separator 450. It will be understood that the signals can be multiplexed using signal characteristics other than frequency according to know multiplexing methods.
The IPG 402 combines the signals of different frequencies for generating the superposition (e.g., multiplexed) signals. It is to be noted that the pulse rate of the energy pulses is neither used for multiplexing the signals of different frequencies nor separating (discussed later) these signals. The IPG 402 delivers the superposition (e.g., multiplexed) signals in the form of a pulsed electrical waveform to the signal separator 450 via the terminal conductor(s) 452. If there are multiple terminal conductors, there may be multiple superposition signals. Moreover, each superposition signal contains signals for one or more electrodes depending on the desired stimulation pattern.
The IPG 402 generates the electrical stimulation signals using a set of modulation parameters. Examples of these modulation parameters include, but are not limited to, electrode combinations, which define the electrodes that are activated as anodes (positive), cathodes (negative), and turned off (zero), percentage of modulation energy assigned to each electrode, and electrical pulse parameters, which define the pulse amplitude (measured in milliamps or volts depending on whether the IPG supplies constant current or constant voltage to the array of electrodes), pulse width (measured in microseconds), and burst rate (measured as the modulation ON duration X and modulation OFF duration Y). Each signal for each electrode can have a different set of modulation parameters.
The signal separator 450 receives the superposition (e.g., multiplexed) signal(s) through the terminal conductor(s) 452 and separates the superposition signal(s) into individual electrode signals. For example, the signal separator 450 may separate the individual electrode signals by frequency. The signal separator 450 is electrically coupled to each of the electrodes 434 through respective electrode conductors 454. The signal separator 450 may be a single device or may be distributed into multiple devices.
The signal separator 450 can be positioned anywhere along the lead. For example, in some embodiments of paddle leads, the signal separator is disposed proximal to the paddle, or within the paddle body 104, at the distal portion of the lead 103. In some embodiments of isodiametric leads, the signal separator is disposed proximal to all of the electrodes, but along the distal end portion of the lead. In some embodiments, the signal separator 450 may be disposed adjacent to the electrodes 434. In some embodiments, placement of the signal separator 450 is at or along the distal end portion of the lead 103, and thus the signal separator 450 can be accommodated without major modifications to the lead 103. In some embodiments, the signal separator may be distributed so that there is a portion adjacent to each electrode (or to sets of electrodes) to separate out the signal for that electrode (or set of electrodes).
In some embodiments, the signal separator 450 may be disposed partway along the lead 103 so that the lead 103 is narrow along one portion and then wider distal to the signal separator 450. Accordingly the narrow portion of the lead 103 may facilitate placement of lead 103 within a relatively tight region in the patient's body. Further, the number of terminal conductors 452 to be embedded into the lead body 104 is reduced, thereby decreasing complexity of the lead forming process, based on the above placement of the signal separator 450 and the fact that the multiplexed signals are fed to the signal separator 450 via a single (or only a few) terminal conductor(s) 452.
The signal separator 450 can include any suitable components for separating the individual signals. For example, the signal separator 450 can include multiple frequency filters, such as band pass filters, high pass filters, or low pass filters, or any combination thereof, to separate or demultiplex and pass the individual electrode signals based on signal frequency. In at least some embodiments, the frequency filters include only passive elements, such as inductors, resistors, and capacitors. In some embodiments, some or all of these elements can be formed as an integrated circuit. Alternatively or additionally, some or all of the elements can be discrete components. In some embodiments, each frequency filter is disposed in a dedicated manner adjacent to the corresponding electrode 434.
The external signal source 556 can wirelessly transmit superposition (e.g., multiplexed) signals 558 to the IPG 502. In order to transmit the signals, the external signal source 556 is operatively connected to an external power supply (not shown), and includes an antenna and a processor. The antenna may include, for example, tuning circuitry and a single coil or a group of coils, each coil having one or more turns and collectively arranged for either uni-directional or omni-directional wireless transfer of multiplexed signals or energy 558.
The processor of the external signal source 556 can be, for example, any microcontroller-based electro-mechanical device, or a computing device, or any combination of such devices. The processor may be configured to perform different tasks. For example, the processor may be configured to detect the presence of an antenna located in the IPG 502 as well as to control electrical parameters, such as frequency, amplitude, and/or power of the energy in the antenna. Accordingly, the external signal source 556 may radiate wireless superposition (e.g., multiplexed) signals 558, which may be received by an antenna (e.g., a coil or a tuned coil) in the IPG 502.
The IPG 502 delivers the wirelessly received superposition signals 558 to the signal separator 550 via one or more terminal conductors 552. The signal separator 550 then separates (e.g., demultiplexes) the superposition (e.g., multiplexed) signals 558 by frequency into electrode signals, each of which is fed to the electrodes 534 via the respective electrode conductors 554.
In some embodiments, the external signal source 556 wirelessly transmits various AC electrical signals 558 of different frequencies to the IPG 502 and the IPG 502 then combines these AC electrical signals to form the superposition (e.g., multiplexed) signal that is delivered to the signal separator 550.
The electrical stimulation system may further include an external signal source 656 that has a structure and function similar to that discussed with regard to external signal source 556. The external signal source 656 can be an external IPG and can be single device or multiple connected devices. In some embodiments, the external signal source can be separated into two modules connected by any suitable device, such as a cable, or in wireless communication. The first module may include the bulk of electronics, such as the processor, power source, and signal generator, and may be worn by a user, such as on the user's belt, or may be located at or on any other external structure. The second module may include an antenna which may be externally positioned, for example, over the proximal conductor or an antenna associated with the proximal conductor to facilitate reliable communication between eh external single source and the lead. External/internal magnets may be used in these embodiments to hold the second module in place with respect to the lead.
The proximal conductor 652 acts as an antenna, which may be tuned using passive elements, to receive signals from the external signal source 656. In some embodiments, the proximal conductor 652 includes an antenna coil, although any wire may act as an antenna. In order to perform this operation, the antenna of the external signal source 656 and the proximal conductor 652 may be designed to have a quality factor so that the coils inductively couple to each other in a reliable manner. The quality factor, referred to as the Q factor, may be defined as a ratio of the apparent power to the power losses in a coil:
The quality factor of a coil may determine, and in some cases largely determines, the degree of frequency selectivity of a tuned circuit that may be achieved using a coil and a tuning element, such as the capacitor. The Q factor may be enhanced or otherwise improved using any known methods.
The arrangements described herein may provide one or more of the following benefits: 1) reducing manufacturing complexity of the lead, 2) providing a broader level of therapy for treatment of different diseases and disorders, and/or 3) reducing the number of electronic components so as to reduce stimulator cost and size, while enhancing stimulator reliability or simplifying the therapeutic procedure.
In some embodiments similar to those discussed in the description of
As another alternative, power can be supplied by an external power source 812 through inductive coupling via the optional antenna 818 or a secondary antenna. The external power source can be in a device that is mounted on the skin of the user or in a unit that is provided near the user on a permanent or periodic basis.
If the power source 812 is a rechargeable battery, the battery may be recharged using the optional antenna 818, if desired. Power can be provided to the battery for recharging by inductively coupling the battery through the antenna to a recharging unit 816 external to the user. Examples of such arrangements can be found in the references identified above.
In one embodiment, the processor 804 may be configured to combine various electrical signals of different frequencies to produce multiplexed signals, which are demultiplexed based on frequency into electrode signals by a signal separator, such as signal separator 450 shown in
Upon receiving the electrode signals, electrical current is emitted by the electrodes 134 on the paddle or lead body to stimulate nerve fibers, muscle fibers, or other body tissues near the electrical stimulation system. The processor 804 is generally included to control the timing and electrical characteristics of the electrical stimulation system. For example, the processor 804 can, if desired, control one or more of the timing, frequency, strength, duration, and waveform of the pulses. In addition, the processor 804 can select which electrodes can be used to provide stimulation, if desired. In some embodiments, the processor 804 selects which electrode(s) are cathodes and which electrode(s) are anodes. In some embodiments, the processor 804 is used to identify which electrodes provide the most useful stimulation of the desired tissue.
Any processor can be used and can be as simple as an electronic device that, for example, produces pulses at a regular interval or the processor can be capable of receiving and interpreting instructions from an external programming unit 808 that, for example, allows modification of pulse characteristics. In the illustrated embodiment, the processor 804 is coupled to a receiver 802 which, in turn, is coupled to the optional antenna 818. This allows the processor 804 to receive instructions from an external source to, for example, direct the pulse characteristics and the selection of electrodes, if desired.
In one embodiment, the antenna 818 is capable of receiving signals (e.g., RF signals) from an external telemetry unit 806 which is programmed by the programming unit 808. The programming unit 808 can be external to, or part of, the telemetry unit 806. The telemetry unit 806 can be a device that is worn on the skin of the user or can be carried by the user and can have a form similar to a pager, cellular phone, or remote control, if desired. As another alternative, the telemetry unit 806 may not be worn or carried by the user but may only be available at a home station or at a clinician's office. The programming unit 808 can be any unit that can provide information to the telemetry unit 806 for transmission of wireless multiplexed signals to the electrical stimulation system 800. The programming unit 808 can be part of the telemetry unit 806 or can provide signals or information to the telemetry unit 806 via a wireless or wired connection. One example of a suitable programming unit is a computer operated by the user or clinician to send signals to the telemetry unit 806.
In another embodiment, the electronic subassembly 810 of electrical stimulation system 800 may not include the receiver 802 and the processor 804. The telemetry unit 806 may wirelessly transmit multiplexed signals to the antenna 818, which also behaves as a receiver.
The signals sent to the processor 804 via the antenna 818 and the receiver 802 can be used to modify or otherwise direct the operation of the electrical stimulation system. For example, the signals may be used to modify the pulses of the electrical stimulation system such as modifying one or more of pulse duration, pulse frequency, pulse waveform, and pulse strength. The signals may also direct the electrical stimulation system 800 to cease operation, to start operation, to start charging the battery, or to stop charging the battery. In other embodiments, the stimulation system does not include the antenna 818 or receiver 802 and the processor 804 operates as programmed.
Optionally, the electrical stimulation system 800 may include a transmitter (not shown) coupled to the processor 804 and the antenna 818 for transmitting signals back to the telemetry unit 806 or another unit capable of receiving the signals. For example, the electrical stimulation system 800 may transmit signals indicating whether the electrical stimulation system 800 is operating properly or not or indicating when the battery needs to be charged or the level of charge remaining in the battery. The processor 804 may also be capable of transmitting information about the pulse characteristics so that a user or clinician can determine or verify the characteristics.
In some embodiments, passive elements constitute the antenna 818 and the receiver 802 which are part of the lead 103. In these embodiment, the processor 804 is not included in the lead, instead functionality of the processor 804 is transferred to the programming unit 808, which is configured to generate the superposition (e.g., multiplexed) signals.
The above specification and examples provide a description of the manufacture and use of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention also resides in the claims hereinafter appended.
This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application Ser. No. 61/845,021, filed Jul. 11, 2013, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61845021 | Jul 2013 | US |
