CA1259664A

CA1259664A - Non-invasive multiprogrammable tissue stimulator

Info

Publication number: CA1259664A
Application number: CA000406401A
Authority: CA
Inventors: William N. Borkan
Original assignee: NEUROMED Inc
Current assignee: NEUROMED Inc
Priority date: 1981-06-30
Filing date: 1982-06-30
Publication date: 1989-09-19
Also published as: US4459989A; EP0072611B1; EP0072611A1; DE3274804D1

Abstract

ABSTRACT:
An electronic tissue stimulator system is provided com-prising a plurality of electrodes to be implanted adjacent tissue to be stimulated in a patient. A transmitting means transmits stimulation pulses for stimulating the electrodes and programming data defining which of the electrodes are to be stimulated and the electrical polarity of the electrodes relative to one another. A receiving means to be surgically-implanted within the patient which receives the stimulation pulses and the programming data, and delivers the energy in the stimulation pulses to the electrodes as defined by the programming data.

Description

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5~6 BACKGROUND OF Tll~ INV~NTION
This invention relates to a partially implanted electronic tissue stlmulator system for controlling various neurological and muscular disorders.
The concep-t of using an electronic stimulation system for the purpose of controlling a nerve or muscle response is well known. This -type of system typically utili~es a pulse generator which remairls outside the patient's body. A transmittinc antenncl receives RL;` eller~Jy Erom the pulse generator and transmit.s this enercJy through the patient's skin to a subcutaneous receiver.
¦¦The receiver provides signal processing oE the received pulses and ¦¦transmits the energy derived therefrom to activate a pair of Ijelectrodes implanted adjacent nerve or muscle tissue. The receiver 'jmay be powered internally by an elec-trical supply such as a rechargable battery pack or in the preferred method, by the energy ¦lin the transmit-ted pulses. A system like the one described above ¦~is seen in U.S. Patent 3,727,616. It is also known in the prior jart to provide a plurality of electrode pairs adjacent a nerve ~jcenter such that the potential differences between the electrodes and the nurnber of elcctrode pairs which are energized controls the number of nerve fibers that are stimulated. Such a system is described in U.S. Patent 3,449,768.
proble~ arlses, however, in -these prior art systems, wile the elcctrode pLacement fai]s to provide the desired physical response. Thls failure may also be caused by improper polarity I of the stimulated electrodes relative to one another. Further-¦ more, it is often required that the electrodes be implanted surgically adjacent to one or more nerve fibers. This -type of procedure involves inherent ris~s due to the fact that i~ is

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; often performed in close proximity to the brain or spinal cord.
It is therefore desirable to perform the electrode implarltation only one time to minimize the surgical risks to the patient as well as the financial burden. Moreover, even when a plurallty I of electrodes have been utilized, such that repeated surgical procedures are not required, the prior art systems have not provided for dynamic progranuning of different electrodes after surgery such that the physiciarl can find the appropriate elec-trodes that produce a de~ired response.
The prior art systems have also proven to be somewhat ineffective in practice due to their inability to provide more :
-than one type of stimulation signal to the electrodes. Speci-¦fically, in the event that the chosen signal does not provideappropriate treatment, another surgical procedure must be performed to implant a unit which can provide a different type of stimulation signal. Further, even patients who respond to one type of siynal might respond better if another type ¦Iwere used, however, -the prior art systems do not generally ~allow the physician such flexibility. Therefore, even though I l !a different stimula-tion signal might be more beneficiaI to the ¦patient, the physician will not usually perform additional Isurgery unless there is no positive response.
I qlhe prohlems Oe the prior art sys-tems have severely ~¦hampered t.he widespre~a(l applicatlon of tissue stimulatlon systems to date, even in areas where they show great promise in relieving disorders which have no other viable treatment alternatives.

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SU~li!~RY OF THE INVENTION
It is therefore an object of the present invention to provide a partially implanted tissue stimulator system wherein the.subcutaneous receiver can be non-invasively programmed any time after implan-t to stimulate different electrodes or change stimula-tion parameters such that a desired response can be attained. Each electrode is capable of assuming a positive, negative or open-circuit status with respect to the other electrodes.
It .is another object of the present invention to provide a tissue stimulator system wherein the electrode program~ing is de:rived from programming data which is modulated on a carrier wave. The carrier wave is then transmitted in bursts which define the stimulation pulses for the electrodes.
It is a further object of the present invention to provide a system of the type described wherein the receiver includes circu1try for determining whether the programmin~ data is being received properly. The stimulation pulses are applied to the electrodes only after a predetermined number of consecutive, identical programming data sec~uences have been received.
I-t is yet another object of this invention to provide a system of the type described wherein the receiver may not require any internal source of electrical power.
It is sti].1 another objec-t of this invention to provide a tissue stimulator system wherein the programming data is retained in the receiver between the recep-tion of stimulation .
pulses unless the receiver is being reprogrammed or the trans-mitter is turnecl off.
It is still another object oE this invention to provide a tissue tlmulator system ~herein the relative polarity of the ~4_ ~i '' ' ` ~L25966~
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s-tlmulated electrodes can be kept constant or be alternated during application of consecutive stimulation pulses to the electrodes.
These and other objects of the invention are attained by providing a plurality of electrodes to be implanted adjacent tissue to be stimulated in a patient. A transmitting means transmits s-timulation pulses for stimulating the electrodes and programming data defining which of the electrodes are to be stimulated and the electrical polarity of the electrodes relative to one another. A receiving means to be surgically implanted within the patient receives the stimulation pulses and the programming data, and delivers the energy of the stimulation pulses to the electrodes as defined in the programming data. :
The programming data is transmitted as a modulated signal on a carrier wave, the carrier wave being transmitted in bursts :
which define the stimulation pulses. The parame-ters of the bursts can be varied by the transmitting means such that the stimulation pulses have different pulse parameters. The receiving means includes detector means to demodulate the sti-mulation pulses from the carrier wave and logic.converter means for separating the programming data from the s-timulation pulses.
The receiving means further includes an error detection means Eor comparing consecutive sequences oE proyrammi.ng data and controlliny delivery oE the ene:ryy in the stimulation pulses -to the electrodes as a function of tlle comparison, this delivery defining a stimulation mocle. In the prefexrecl embodiment of -the inventioll, this energy is delivered to the electrodes after a predetermined number of consecutive, identical sequences of the programming data are received by the receiving means. The receive~ is ln a programming mode prio- to re~eivinl th~ iden-~2S96~

tical sequences. The receiving means further lncludes a voltagestorage means ~or s-toring the steady-state energy derived from the stimulation pulses. Also, a loss of vol-tage comparator means is provided which continuously compares the energy in the voltage storage means with a predetermined voltage to control the error detection means. The loss of voltage comparator means resets the error detection means when the eneryy in the voltage storage means is less than -the predetermined voltage, this reset serving to return -the system to a programming mode.
The rece~ivirlg means further includes a channel enable means controlled by the programming data and the error detection means for preventing energization of the electrodes until:
; (a) the error detection means determines that a pre- ..
determined number of consecutive, identical sequences of the programming da-ta have been received, (b) one of two redundant receivers in the receiving means has been selected for ~
operation, and (c) no invalid electrode proyramming combination:
which would short the receiving means is defined in the pro-yramming data.
I'he receiving means further includes a memory means, which may be volatile or non-volatile, for storing the pro-gramminc~ data and a mono/biphasic control means connected to the memory means Eor controlling the relative polarity o~ the stimulated elc-~ctrode.s during applica-tion Oe consecutive stimu-lation pulses. Al.so, the receiviny means i.ncludes an output control logic means connected to the memory means, the output control logic means being controlled by the channel enable means.
A plurality of output switches are connected -to the output control logic means and are controlled by the programming data to deliver the energy in the stimulatlon pulses to the electrodes 1 ~ :

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1! :12~596~4 The receivinymeans further in¢ludes a delay means for con-trolling the output control logic means to delay the applicatlon of the stimulation pulses to the output switches. A clock cir-cuit means is provided for controlling the delay means and for applying the proyramming data to the memory means. The period of the delay rneans is at least eclual to the period of a pro-gramming data sequence such that the stimulation pluses are not applied to the ou-tpu-t switches until after the programming data sequence has been stored in the memory means.
The receivincJ means may be powered by the energy trans-mitted by the transrnitting means, or al-ternatively, by an lnternal energy source, or a combination of both sources.
The invention also contemplates a method of providing tissue stimula-tion comprising the steps of surgically-implanting `
a receiving means in the patient, surgically-implanting a plurality of electrodes connected to the receiving means adjacen~t tissue to be stimulated in the patient, selecting firs-t programming data defining which of the electrodes will be stimulated and the electrical polarity of the electrodes rela-tive to one ano-ther, and transmitting the first selected pro-gramming data to the receiving means to produce a response.
Should the first programming data fail to produce a desired ¦response, the me-thod further provides for: selecting second proqrammilly data, difEerent from the first programmillg data;
definillcJ a new combina-tic)n of electrodes to be stimulated or a new polarit~ of the stimulated electrodes; and transmitting this second selected programmincJ data to the recelving means.
The method further provides for trial of various electrode combina-tions and polari-t.ies at various stimulation pulse frequencies, widths, and amplltudes such that the appropria-te combination of these parameters may be comblned to provide a desir~d response.

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I BRIEF D~SCRIPTION or THE` DRAWINGS
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Figure 1 is a simple block diagram of the overall system of the invention.
Flgure 2 is a block diagram of the receiver of the invention .
Figure 3 shows signal waveforms at various stages of the receiver circuitry.
Fiyure 4 shows a schematic diagram of the detector circuit, voltage storaye circuit, and logic converter circuit oE the receiver seen in Fiyure 2.
Figure 5 shows a schematic diagram of the clock circuit and the bit counter circuit of the receiver.
Figure 6 shows a schematlc diagram of the shift register ¦ of the receiver.
-~, ~ Figure 7 shows a schematic diagram of the error detection , circuit and the loss of voItage com~arator circuit of the receiver.
Figure 8 shows a schematic diagram of the channel enable ~;1 logic circuit and the mono/bi.phasic control circuit of the receiver.
Figure 9 shows a schematic diagram of the output control 1 ~1 logic circuit and outpu-t switches of the receiver for one of `, I the electrodes.
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DESCRIL"rION OF TIIE P~FERRED EMBODIMENT
Referring now to the drawings, specifically-Figure 1, a simplified block diagram of the overall system is provided.
The system includes a transmitter 10 and a receiver 12, the latter being surgically implanted beneath the patient's skin 13.
The output of the receiver 12 is coupled via a plurality of lead wires 16a - 16d to a plurality of electrodes 18a - 18d. ::
In the preferred embodiment of the invention, four leads are utilized, however, any convenient number of electrodes may be iïnplanted a5 desired. Electrodes 18 are implanted adjacent the tissue to be stimulatecl, for example, nerve or muscle tissue. ~
The receiver 12 may be manufactured by thick or thin-film hybrid technology or on a single integrated circuit using state-of-the-art technlques. I
he transmitter 10 of the present invention includes pro-~ :gramming con-trols (not shown) as well as transmitting circuits.
In operation, the attending physician is required to select the specific pulse parameters that he clesires for a speclfic patient.
Through the programming controls, programming data is generated as a function of the physician's selec-tion. This data generally includes control inEormation defining which of the electrodes 18 are to be stimulated, as well as the electrical polarity oE these electrodes relative to one another. It is an important feature of the present invention that each oE the electrodes 18 is capable of assuming a proyrammed positive, negative or open-circuit status with respect to the other electrodes. Using the progralr~iny controls, the physician can modify the electrical configuration of the electrodes 1~ to obtain the best response possible for the patien-t. If the selected electrodes fail~to produce the clesired response, the physician need only reprogram the transmitter 10 and transmit the new programming data.
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~259G64l The transmitter 10 includes a source of sinusoidal energy which functions as a carrier signal. In the preferred embodi-ment of the invention, the prograrnming data is a pulse width modulated siynal which is amplitude modulated onto the carrier signal by a modulation circuit. Such a circuit is well known ln the ar-t and forms no part of the instant invention. I-t should be recognized that although a pulse-width modulated signal is specifically discussed, any other type of digital,magnetic, or ¦~ analoc~ sicJrlal capable of defining the programming data may be utilized. q'he carrier is pulsed on and off as a "burst" slgnal to form the stimulation pulses which are transmi-tted by the transmitte r ~; 10 to the receiver 12. The parame-ters of the burst, such as ampli-tude, frequency and width, are preferably selected by the attending physician throu~h the prograrnming controls such that the resulting stimulation pulse signal can have different wave-shapes. Also, the electrode impedance a-t specific frequencies and locations can be used to help determine which electrodes give the ; best response. This f~exibility allows the physician to further ¦~control the stimulation response.
¦I Note that although the transmitter 10 is shown'in Figure 1 ' ¦ as located external to the patient, it should be recognized that this placernent is not meant to be limiting. The transmitter may j also be implanted in the pa~ient and be reprogrammed by measured ~internal physiological vari.cl~les and/or a combination o~ external ¦programming, measured variablesand specific preprograrnmed storecl parameters. It may also be desirable to have -the transmitter and receiver formed as an integral unit using internal and/or external power and programming sources.
Turnin~ now to Figure 2, a block diagrarnof the receiVer 12 is shown. This device includes an antenna 20 coupled to ~13 ` a detector circuit 22 which provides envelope detection of the ' `' 1 ~ ~
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transmitted signal -to remove the carrler signal. With reference to Figure 3a, the transmitted burst is shown comprising the carrier signal 26 which includes the pulse width modulated programming data riding as a ripple. The output of the de-tector circuit 22 is seen in Figure 3b as an envelope of the transmitted burst with the carrier removed, and includes the transmitted pulse Vp and the programming data 28 modulated thereon. It should be noted that the transmitted pulse Vp in-cludes the stimulation pulse Vs as seen in Figure 3b. In parti-cular, the stimulatiorl pulse Vs~ is that portion of the transrnit-ted ¦pulse Vp which doesn't include the progra~ning data sequence. In the preferred embodimen-t of -the invention, the programming data 28 is modulated on the first half of the transmitted pulse Vp~
Therefore, -the second half of the transmltted pulse Vp is used as the stimulation pulse Vs The output of the detector circuit 22 is connected to a logic converter circuit 30 which decodes the programming data ¦28 from the transmit-ted pulse V . ~he transmitted pulse Vp which includes -the s-timulation pulse Vs, is routed via conductor 32 to the output switches 34 connected to the electrodes 18. The ¦steady state or long-term energy derived from the`received pulses is stored in a voltage storage circuit 36 as a voltage signal Vm.
TI1e decay time oE the vol-tage signal Vm is much longer as compared with the time between reception of the transmitted bursts, and l there:Eore this voltage is used to power the receiver circuitry I between the reception period. This feature also allows Eor continu ~d system operation during those brief periods when the receiver might lose the transmitted signal due to dislocation of -the ¦antenna 20 during routine activities OL daily living. It should ' be no-ted that a small, internal power source could be incorpo-rated into the receiver t~ augnent or replace the voltage 1.

` ~ 259~;6 j storage circuit 36. Such an inter~al power source serves to con-vert the receiver memory, to be described below, into a non-volatile memory. Thus, once the receiver is programmed, stimula-tion can be achieved by transmitting stimulation pulses without the programming data. In practice, the physican will program the receiver at the hospital using a sophisticated transmitter. The patient would then re~uire only a simple transmitter at home which ~1 could derive stimulation pulses.
The output of thc lo~ic converter circuit 30 is seen in Figure 3c and consists of the pulse width modulated progra~ning data 2~ deXining which of the electrodes 18 are to be stimulated, ~ the electrical polarity of these electrodes relative to each ., I
other, whe-ther the electrodes will be stimulated in the mono or biphasic mode, and which of two redundant receivers or channels (if two are used) are to be activated. The monophasic mode lS
one wherein the polarity of the stimulated electrodes is kept 1I constant. In the biphasic mode, the relative polarity of the I stimulated electrodes reverses with each stimulation c~cle.
The programmlng data 28 is applied to input 29 of a clock - I circuit 38 ~hich forms clock pulses 39 for the rest of the receiver circuitry. These clock pulses, which are seen in Fiqure 3d, have a duty cycle which is a function of the carrier frequency, the carrier si~nal being applied to the clock circuit via conductor ~3. The programmlng data 28 is further applied via conductor 40 -to the data input of a memory comprising a serial--in, parallel-out shift re~3ister 42. I'his data 28 is clocked into -the data input of the shift register by l:he clock ¦ pulses 39 pxoduced by the clock circuit 38 and delivered to the clock input of the shift reqister via conductor 44. The data I inmput to the shift register is seen in Figure 3e.
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~ -12-~ 11 , , , .25g~6 The shif t register 42 includes a first ou-tput data bus 50 for connec tincJ a por tion o:E the programming data 28 to an out-put control logic circuit 52. This portion of the programming data determines which electrodes will be s~imula-ted and the relative positi.ve or negative polarity of these elec-trodes. The output control logic circuit 52 drives the plurality of output switches 34 -to route the s-timulation pulses Vs from conductor 32 . to the appropriate electrodes :L8 defined in the programming data 28.
The shift register 42 includes a second output data bus 54 which connects a second portion of the programming data~ 28 I ~to a mono/biphasic control circuit 56. This circuit: allows ~
the physician to proyram for stimulation pulses of alternating: : :
polarity. As stated above, in the monophasic mode, the relative polarity: of the stimulated electrodes remalns constan-t; howeve~r, n the biphasic mode, this polarity reverses on each stimulation cycle. Tllis feature is selected during programming by the pro-¦¦gramming controls and is transmitted as a portion of the:pro-l¦ gramming data 28. The output o~ the mono/biphasic control ~:~ : I :
.~ ~ circuit 56 is connected to the ou-tput control logic circuit 52 via conductor bus 57 such that -the mono or biphasic parameter can ¦~ be usec~ to control the stimulation pulses applied to the electrocles.
A thi.rd ou-tput data bus 58 of the shi~t register 42 connects :
a final portioll oE t~le proyralluning data 28 to a channel enable logic ci.rcuit 60. This circuit is incorpora-ted to allow for the possibility of adding a second receiver. In particular, ~ the channel enable programming data, also programmed by the physi~

cian, may syeci.fy which of two redundant circuits in the same - ¦I receiver packacJe, A or B, is -to be activated by the stimulation ~pulses. This feature is desirable should one receiver ~ecome '`
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~25~664 j¦defective or a secorld receiver be required to stimulate another ¦ group of electrodes in a separate region of the patient's body.
More importantly, the output c~f the channel enable logic circuit 60 also controls the routing of the programming data 28 through the output control logic circuit 52. In particular, when the channel enable logic circuit is activated~ as would only occur ¦when (a) the appropriate channel A or B has been selected, (b) a precletermined number of consecutive, identical.programming ; ~ data sequences have been received, and ~c~ no invalid electrode combinations wl~ich woulcl short the receiver have been selected, ¦la pulse on conductor 63 is transmitted to output control logic circuit 52. ~hls signal, in combination with the output of bit :
control circuit 31, to be described below, is used to control -the applicatioll of the stimulatlon pulses V to the output switche~
34. Note that if an invalid comblnation is selected, a disable signal is outputed from the output control logic circult 52 on j llconductor 64. ~
1l The pulse-wid-th modulated programming data 28 is also applied to one input 65 of an error detection circuit 66 via ,conductor 46. The other input 67 of the error detection circuit ¦~is provided by the serial output 69 of the last bit of the ¦¦shift register 42 over conductor 47. The elock pulses 39 are ~also apylied via conductor 45. When the error detection circuit determines that a predeterminecl number of consecutive, iclentical secluences of progra~ning data have been received, an output ~enable slgnal is provided via conductor 68a to enable the channel enab:Le logic circuit 60. In the preferred embodiment, four consecutive, identical sequences are :required. A bit counter circuit 3]. ShOWII in Figure 2 receives a signal over conductor 49 from clock circuit 38. The bit counter is a ~10 flipflop con-figuration commonly known in the art. The output of this circuit , ''~ ' : . ' s~
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lS used to control the output con-trol logic such that the output switches canno-t be turned on until the ten data bits of the pro-gramminy data sequence have been received. This clrcuit thus form~
delay means for delaying application of Vp to the electrodes.
Therefore, only the stimulation pulse Vs of V will be applied to the output switches. As described above, the channel enable logic ~;~ circuit 60 and the bit counter circuit 31 control the output Coll-trol logic circuit 52 and the output switches 34 -to deliver the energy o~ the stimulation pulses Vs to the electrodes 18 defined in the procJramming data 28. During stimulation, the output enable slqnal from the error detection circuit 66 functions to turn~the clock circuit 38 off via conductor 68b. The programming data, 1 however, remains in the shift register 42~ontil the voltage Vm; ! ::~
decays to a predetermined value, such as will occur when the~trans~
mitter is turned off or the antenna 20 is decoupled from the receiver. Thus, once four consecutive, identical programming data~
sequences are received and the channel enable logic~clrcult 60~ lS~
enabled, the subsequently-received stimulation pulses are applied~
to the electrodes wlthout fur-the} programming after the bit counter circuit 31 times out. ~ ¦
inally, a loss of vol-tage comparator circuit 70 is pro~
vided to detect when the voltage Vm in the voltage storage 36 decays below a predetermined value. Specifically, the circuit~
receives the voltage Vm stored in the voltage storage circuit 1 36 at one input 7L and compares this value with a predetermined internally set reEerence voltage Vref received at its second I
input 73. Should the voltage Vm be less than the reference voltage as would oocur if the transmitter is turned off or the stimulation pulses~are not being received properly, an out~ut ;
~` ! signal on conductor 72 resets the error detection circuit~66, which disables tKe channel enable logic circuit 60. Once the channel enable logic circuit 60 has been disabled, four -15- ~ , '' I
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consecutive, iclentical programming data sequences must be received before the receiver can provide stimulation.
Summari~ingj when the transmitter is turned on, the receiver logic will look for four consecutive, identical stimulation pulses. This part of the receiver operation defines a pro-gramming mode. Once -these sequences are received, the error detection circuit 66 and the channel enable logic circuit 60 lock in and route the stimulation signal to the output switches to deliver t:he energy of the stimulation pulses to the electrodes after the bit counter circuit times out for each burst. This part of the receiver operation defines a stimulation mode. If the programming data fails to produce a desired physical response, the physician can reprogram the transmitter to form a new sequence of procJramming data, this sequence defining a different polarlty or mono/biphasic capability, or a different combination of elec-trodes. Before reprogramming, the receiver must be disabled by turnlng ofE the transmitter or decoupling the an-tenna 20 such that the loss of voltage comparator circuit 70 resets the error detec-~jtion circuit 66. When th]s occurs, the circuit can re-enter the programmincJ mode. Alternatively, the receiver could monitor the programming signal continuously so that any change in programming woulcl alter the contents of the receiver memory.
With reference to Figure 4, the cletector circuit 22, voltac3e StOraCJe circuit 36, and logie converter circuit 30, are shown in detail. More speciEically, the transmit-ted stimulation ~pulses are inductively coupled transcutaneously to the receiver hy inductor 74. Diode rectifiers 76 and 77 are connected to the inductor 74 to rectify the received signal. Capacitors ¦ 78 and 79 are chosen to respond only to envelope variations in the rectified signal so as to filter out the carrier signal ~ l26 and provide a proper ground reference for the rectified signal.

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The output of the detec-tor circuit 22 is stored as voltage ~Vm in the voltage storage circuit 36 which comprises diode 80, capacitor 82, optional zener diode 83 and resistor 84. Alterna-tively, a rocllargeable voltage source could be substituted for capaci-tor 82. The short-term output of the detector circuit 22 is the transmitted pulse V which includes the pulse-width modulated programming da-ta 28 on its envelope as seen in Figure 3b. The transmitted pulse Vp is applied to the logic converter circuit 30 which serves to decode the programrning datcl 28 from the stimulatio pulses Vs. 'I'ile loc;ic converter is well known in the art and ~comprises an operational ampl.ifier 86, resistors 88, 90 and 94, and capacitors 98 and 100. Note that other configurations of I lthe signal shaping passive componen~s rnay also be used. The ~l outpu-t of the logic converter 30 is inverted by the NAND gate 101 to form an inverted programming data signal which is applied : Ito (a) the input 29 of the clock clrcuit 38 of Figure 5; (b) the data input of the shift register 42 of Figure 6; and (c) the inpu-t 65 of the error detection circuit 66 of Figure 7. A NAND
gate 89 is provided to form an inverted stimulation pulse Vp The clock circuit 38 and bit counter circuit 31 are shown in ¦
detail in F'iyure S. The clock circuit consists of a control D-flip-flop 102 whi.ch includes a clock input 29, a data input, an invertec ~¦Q output, and a reset line. The rest of the clock circuit com-pri.ses four seria'Lly connec ted D flip-flops 104, 106, 108 and 110.
'rhese flip-EloE)s are arrallged as a divide by eight coun-ter, with the c'Lock input of the counter being derived from the carrier signal via conduct:or 43. The non-inverted Q output of the last flip-flop 110 oE the counter is connected to the reset line of the ' control flip-flop 102. Also, the inverted Q output of the flip-flop 102 is connected to the reset lines of the counter flip-flops 104, 106, loa and 110. ~

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,f !L ~2596i~1 In operation, the pulse-width modulated progra~ning data, ¦which is invertecl by NAND gate 101 of Figure 4, is applied to ¦the clock input 29 of the control flip-flop 102, so that the first falling edcJe in the signal will toc~gle the inverted Q
output of this flip-flop to a 1ogic low state. This signa~ resets -the counter Elip-Elops 104, 106, lC8 and 11~ via their reset lines, such that the counter will start countincJ carrier pulses from zero. After eight cycles of the carrier-wave are counted, -the non-inverted Q Outpllt of flip-flop 110 yoes to loyic hiyh I and resets the contro:l flip-flop 102, terminating the pulse on its inverted f') output. 'l`he Q pulse from the control flip-flop 102 is the clock pulse 39 for the rest of the receiver circuit.
It should be obvious to one skilled in the art that clock circuit

3~3 ac-ts essentially as a monostable multivibrator, or one-shot ¦circuit, with the pu]se-width modulated data beiny used simply to trigc3er generatioll oE tne clock pulses at a frequency deter-mined by the programming data and with a duty cycle determined by the carrier frequency.
The bit counter circult 31 is also shown in Figure 5. This ,¦circuit comprises D flip-flops 103, 105, 107, and 109 connected as a divide-by--ten counter, and N~ND gates lll and 113. The clock input to flip-flop 103 is provided by the non-inverted Q output of flip-Elop 102 o~ the clock circuit 38. The inputs to NAND gate 111 are provldecl by the non-inverted Q outputs of f1ip-elops 105 and ¦ 109. 'l'tlereeore, after ten bits o~ programminy data have been i receivecl ~y tlle bit counter circult 31, -the output of NAND gate 111 goes logic low. 'rhis logic low signal is invertecl by NAND gate ¦ 113 and appJied ~to the output control loc3ic circuit 52 viaconductor 51 as will be~ described in detail below. The inverted transmitted ¦ pulse Vp is used to reset -the counter via the reset inputs of , ¦of flip-flops 105, 107, and 109. Thus, the bit counter circuit is f I reset after each transmitted pulse.

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The shl~ recJister 42 of the receiver 12 is shown in Fiyure 6, and comprises ten D-flip-Elops 112-121 connected in a serial-in, parallel-out structure. In particular, the non-inverted Q
output of the nth s~tage of the shift register 42 is connected to the data input of the succeeding or n+lth staye. The inverted , programming data 28 is applied from NAND gate 101 of the logic ; converter circuit 30 in Figure 4 to the data input of the first flip-f],op 112 of the shift register 42 over conductor 40. The clock pulses 39 derived from the clock circuit 38 of Flgure 5 . I are auplied to the clock inputs of each flip-flop 112-121 via ', I conductor 44. The inverted Q and the non-inverted Q outputs of flip-flops 112-121 form the first output data bus 50~which:
~:~ !connects a portion of the programming data 28 to the output control logic circuit 52 of Figure 9. The non-inverted Q and nverted Q outputs of f~ip-flo~ 120 form the second output data ~¦
bus 54 which connects a second portion of the programming data 28 to the mono/biphasic control circuit 56 of Fiyure 8. Finally, the non-inverted Q and ,inverted Q outputs of flip-flop 121 form the third O-ltpUt da-ta bus 58 for connecting the final bit ¦jof the shift reglster 42 to the channel enabIe logic circuit 60 of Figure 8. Also, the non-inverted Q output 69 of the ¦last flip-flop 121 is connected to the error detection circuit 66 ~f FlcJure 7. The number of flip-flop~ in the shift regis-ter 2 is equa:L to the number of bits in the programming data sequellce. Note that although ten bits are sho~n in the pre-ferred embodiment, any number may be used such that other pro-, I g.ra~nabl.e parameters may be speci~ied by the programming data.
.~ ~ ~lso, it is ellv.is.ioned that the shi~-t register 42 comprises either volati].e or non-volatile elements.
:~ I The error detection circui-t 66 is seen in Figure 7 and ~ 9~ comprises exclusive NOR (X-NOR) gate 122, NA~D gate 124, and , ~

`- - .

!1 1259~6~

D flip~floys 126, 128, 130 ancl 132. The flip-flops 128, 130 and 132 define a three count ring counter 133. One of the inputs 65 of the X-NOl~ gate 122 is tile i.nverted prograrr~ling data 28 from NAND gate 101 of the logic converter in Figure 4, while the other input 67 is provided by the non-inverted Q output 69 of the last flip-flop 121 of the shift register 42. The output of the X-NOR gate 122 is logic high if both of the inputs are hic,~h or botil are low; o~herwise, the outpu-t is low. Since the inputs to the X-N~R gate 122 are the input and output of the shiEt recJister 92, the output of the X-NOR c~ate 122 indicates whether the bits of th~ incoming programrning data se~uence match the hits of the previously-received programming data sequence.
The output of the X-NOR gate 122 is connected as one input to tlle NAND gate 124, the output of which is connected to the data input of the Elip-flop 126. The other input to the NAND
gate 124 lS provided by the inverted Q output of flip-flop 126.
The clock pulses from cloc]c circuit 38 of Figure 5 are connected , ` ~to the clock inpu-t of flip-flop 126. The inverted Q output f t:he flip-flop 126 is also connected to the data input of the ring counter 133. The non-inverted Q output of the last flip-flop 132 in the counter 133 is rou-ted via conductor 68a to the channel enable loyic circuit 60 of Figure 7 and to the output cont:rol logic circuit 52 of Figure 9 via con~uctor 68c.
'l'he illverted Q output o tlle flip-flop 132 is routed via conducto:r 68b to d:isabl~ th~ clock cireui.t 38 by provicling a locJic .low to thc clata input oE the coritrol flip-flop 102 in Figure 5. Thus, A logic hicJh on the inverted Q Outp-lt of flip-E:Lop 132 keeps the receiver in the programming mode and a logic low places the receiver in the stimulation mode.
Finally, the reset line Oe flip-flop 126 is tied to the inver-ted ~transmitted pulse Vp provided by NAND gate 89 in Figure 4, and the clock inpu-ts of the flip-flops 128, 130 and 132 are tied to the non-.inverted Vp signal.

! -20-' IL

Figure 7 also sllows the loss of voltage comparator circuit ¦70 which compares the energy Vm in the voltage storage circuit 36 of Figure 4 to a predetermined voltage V ef In particular, the long-term voltage Vm is applied to one input~of~a com-parator 134 via a resistor divicler network 136, 138 and 140.
The reference voltage, which is in-ternally preset, is applied I to the other input of the comparator 134. An output slgnal frorn the comparator 134 occurs whenever the voltage Vm is less than the predetermined reference voltage. As discussed above, this conditiotl occurs when the receiver is no longer receiving stimulation pulses, or the pulses are not being received I ~ properly. The loss of voltage output is routed via conductor 72 to the reset line of the counter 133 ln the error de-tection circuit. Thus, wheD a loss of voltage occurs, the error detection circuit is effectively reset and the receiver can re-enter the programming mode. 'rhereafter, four consec~utiv5, identical programming data sequences must again be received :', il ¦before the receiver goes back into the stimulation mode.
The operation of the error detection circuit 66 of Figure 7 will now be explained in detail. The inverted pulse Vp resets ~ ¦ flip-flop 126 for~each transmitted burst received by the receiver.
; ; I Therefore, the inverted Q output of flip-flop will be a logic high ; ~ signal which iS applied to N~ND gate 124. ~s lOIlg as all the data bi-ts o~ consecutively-received programming data sequences match, ~the O-ltput of X-NOR gate 122 will be logic high. Since both inputs of N~ND gate 124 are logic high, its output is a logic low signal which is applied -to the data input of flip-flop 126. Note that Elip-flop 126 is clocked every bit of the programming data by the clock pulses 39 of Figure 3d to keep the inverted Q
output at logic high. If the inverted Q output of flip-flop ~1 ~ ~126 lS logic high at the en~ of the sti~lati~n pulse, thls ~ : .
:~
,, :

` 1 3L25~6~4 loyic h~gh signal is applied to the data input of the counter ¦¦ 133, indicating that consecutlvely-received pro~ramming data sequences are identical. After three identical sequences are consecutively-received and found to be identical with the : initial sequence received, the ring counter 133 will provide a logic high output from the non~inverted Q output of flip-flop 132. This output is coupled via conductor 68a to the channel .~ enable logic circuit 60 and indicates that the receiver may en-ter the stimulatic)ll mode. The inverted Q output of flip-. flop 132 goes to logic low during the stimulation mode to disable the clock circuit 8a of Figure 5 via the conductor 68b.
It may also be used to disable the other parts of the receiver once the unit is programmed. :
If any of the bits in the incoming programming data~, how- : :~
lever, do not match the bits in the previousIy-received programming:
data sequence, the output of X-NOR gate 122 l5 logie low and :
therefore the output of NAND gate 124 is logic high, This : I logic high signal causes the inverted Q output of flip-flop ; 126 to go to logic low, and -thus NRND gate 124 will con-tinue to provide a logic high output until the incoming data bits match the prevlously rece~.ved data bits. In addition, a loss of voltage signal on conductor 72 may also be applied to reset the counter 13 , sueh that the receiver can re-enter the programming mode after a 105s of voltage.
Referrinc3 IIQW to r`icJure 8, the mono/bipha.sic control. 56 ~ and the channel enable logic 60 circults are shown. More speci-:1 ~ fically, the mono/biphasic con-txol circuit 56 comprises flip-flop 148. The mono/biphasic programming data Qm is applied to the reset lirle of flip-flop 148 via eonductor 54 from flip-! flop 120 of the shift register 42 in Figure 6. The elock ; :inpu-t of the flip-flop 148 is the inverted transmitted pulse , ~, ~
!' . . .
....

6~
IVp which is provided by NAND gate 89 of Figure 4. The da-ta ; input of flip-flop 148 is connec-ted to the inverted Q output of the flip-flop :l48. The inverted Q and non-inverted Q
outputs of flip-flop 148 are routed to the output control logic circui-t of Flgure 9 via conductor bus 57.
As stated above, when monophasic operation occurs, the relative polarity of the s-timulated electrodes remains constant throughout the stimulation mode. In the blphasic mode, how-ever, this polarity alterna-tes with each stimulation pulse.
For example, iE electrodes 18a and 18c are to be stimulated, and electrode 18a is to have positive polarity while el.ectrode ~18c a nega~tive polarity; then during the biphasic mode, the polarity of these two electrodes will reverse with every sti-j mulation pulse such that electrode 18a wiIl be negative andelectrode 18c will be positive.
¦ In operation of the mono/biphasic control circuit 56, the ~ l inverted signal Vp causes clocking at the end of the stimulation ¦ ;
1~ Ipulse since the Elip-flop 148 is clocked with a rising edge. If ., ~ f the mono/biphasic bit Qm of the programming data 28 is logic low, ~which indicates monophasic mode, then~the non-inverted Q output~
¦ of flip-flop 148 will be logic high. The inver-ted f~ output of flip-flop 148 will be loyic low and this sicjna1 will be applied to !
the data input flip-flop 198. Since the flip-flop 148 is not reset ¦¦every transmitted pulse, its outputs remain constant. ~Iowever, should the mono/biphasic control bit be logic high, which indica-te~
¦biphasic mode, then the inverted Q output of flip-flop 148 will be¦
a logic high. This signal is applied to the data input of flip-flop 148. The non-inverted Q output of the flip-flop 148 will be a loglc low. On each subsequent tramsmitted pulse, the flip-flop 148 will be reset since the bit Qm is logic high. I'herefore, the outputs of the flip-flop 148 will alternate logic states. l'hese outputs are routed via conductor bus 57 to the output control logic circuit of Figure 9.

1i ~
-~: -23-. .

Il .
The channel enable logic circuit 60 is also shown in ~
Figure 8. This circuit comprises NAND gates 150-157. NRND
yate 156 is the control gate and provicles a logic low output only when the following conditions oecur simultaneously:
: (a) the proper channel has been selected; ~b) four consecutive, identical proyramming data sequenees have been received by ;
the error cletection circuit 66 of Figure 7; and (c) no invalid I~ electrode combina-tions which would short the receiver have ;~ been se]ected. More specifically, the ehannel enable function is selected by N~D yates 150-153. In -the preferred embodiment of the invention, it is desired that two redundant receivers ¦Wl11 be present 1n the same receiver package. The use of two~recelvers provides greater flexibility in that the second ~ receiver may be used for a different set of electrodes or as "1~ a ~backup should tl-e initial reeeiver become~clefectlve. ~ ~ ¦
In operation, each of the rece1vers includes~a p1n which ~
will be grounded or tied to~a positive vo1tage, depending on ~ ~ ;
whether it wi11 be designatecl channel A or B. This connection ~is applied via aonductor 158 to the lnputs of NAND gates 150 ~and 151. The other input of NAND gate l51 is the programming data blt Q~ Erom the non-inverted Q ou-tput of flip-flop 121 of shift register 42 in Figuré 6. The signal on conductor 158 is inver ted by N~ND gate 150 and applied to one input of NAND
gate 152. The other input o~ NAND gate 152 is the programming data bit QE rom the inverted Q ou-tput of ~lip-flop 1.2L of shift recJister 42 :in FicJure 6. ~ssuming that reeeiver A is to be utilized, conductor 158 will be tied to a posi-tive`voltage I and the programm1ng data bit QE will be logic high. Therefore, the output of NAND ga-te 150 will be logic low and the output of NAND gate 152 will be logic high. ~owever the output of NAN

~ 1 ~ ; :

~ -2~-,, .

' ' j ~ :259~6~
~gate 151 will be logic low and therefore -the output of NAND
gate 153 will be logic hicJh, indica-tiny a channel has been selected. If receiver B is to be utili~ed, conductor 158 will be tied to ground and the programming data bit QE will be logic high. Therefore, the outputs oE NAND gates 150 and 152 will be logic high and low, respectively. Since the output o~
NAND gate 152 is low, the output of NAND gate 153 is high and a channel has been selected. This output is applied to control NAND yate 156.
The outpu-t of the error detection circuit 66 of Figure 7 is routed via conductor 68b to another inpu-t of NAND gate ~156. This output will be logic high whenever four consecutive, identical programming data sequences have been received. The I
~flnal input of control NAND gate 156 i5 from the output control logic circuit 52 of Figure 9 via conductor 64. In particular, a low signal on this conductor indicates that an invalid electrode polarity combination has been selected for one of ¦~
; I the electrodes by the physician. This low signal is applied ; llto one input of NAND gate 154.~ The o-ther three inputs of NAND gate 154 are derived from the output control logic of ¦the other three electrodes. If an invalid combination is ~¦selected, the outpu-t of NAND gate 154 is loglc high. This ; llsignal is inverted by NAND ga-te 155 to disable the control NAND
~yate 156. IE no invalid coMbinations Iave been selected for each electrode, the output of NAND cJa-te 155 is logic high.
Therefore, si.nce all -the inputs of I~ND gate 156 are logic high, its ou-tput is logic low. q'his signal is inverted by NAND gate 157 and applied via conductor 63 to the output ~ control logic circuit 52 of Figure 9. Therefore, a logic high j ¦¦signal on conductor 63 indicates that (a) the proper channel has i ~
~ -25-, ~

I

:

3L25~
been selected, (b) four conseeu-tive and identical programming data sequences have been received, and (c) no invalid electrode combina-tions have been selected. This logic high siynal indicates that the receiver is now in the stimulation mode.

Turning now to Fiyure 9, the output control logic 52 and the output switches 34 for one of the electrodes 18 is shown.
It should be noted that the output con-trol logic for the other three electrodes 18 will be identical to the circuit seen in l?igure 9, except they will have inputs from different f:Lip-flops of tile shi[t re~ister 42 of Figure 6. In operation, two programming data bit~ from each set of programming data 28 control each electrode 18. The use of two bits allows each electrode to assume a positive, negative or open eircuit status with respect to the other electrodes. More speeifically, if the neyative polarit~ control bit Qn is stored in one of the flip-flops 112-121 of shift register 42 of Figure 6, the positive polarity control bit Qp is stored in the next sueceeding flip-flop. l'he flip-flops provide non-inverted and inverted ¦¦outpu-ts of the positive and neyative polarity bits which are routed via conductor bus 50 to the output control loyic clrauit 52. The eontrol bits may be put in any eonvenient order other tllan tha-t described above.
Referring now specifically to F'igure 9, the output control loglc for electrode 18a is provi.ded. For this electrode, the ~¦necJative and positive procJrammincJ data bits are stored in flip-flops 112 and 113, respectively, of shift recJister 42.
The neqative and posi-tive progran~ing data bits for the other three electrodes are stored in flip-flops 114-121 of shift rec~ister 42 in Fiyure 6. The inverted output Qn of flip-flop 112 is applied to a yated switch 158 and to one input of a NAND c3ate 168. The non-inverted output Qn of flip-fIop 112 .

ll is applied to gated switch 160 and to one input oE a NAND
l gate 166. The non-inverted output Qp of flip-flop 113 is ; applied to ~ated switch 162 and to the other input of NAND
gate 168. The inverted output Qp of flip-flop 113 is applied ~1 to yated switch 164 and the second input of NAND gate 168.

1~ The output of NAND yate 166 will always be logic high unless the electrode is to be left open. The ou-tput of NAND gate 168 is applie-l via conductor 64 to -the channel enable logic circuit 60 o.E Fiyure 8 -to indicate whether an invalid electrode .
combination has been selected. With reference to truth table ¦170, this condition occurs whenever bo-th the non-inverted Q
~outputs of flip-flops 112 and 113 are logic low.
The gated switches 158, 160, 162 and 164 are ~co~trolled ,¦by the output of the mono/biphasic control circuit 56 oL
~:~ IFigure 8. In par-ticular, the inverted Q output of flip-flop 148 of the mono/biphasic control circuit 56 is applied as the yate signal to gated switches 158 and 162. Also, the non-inverted ~ output of fIip-flop 148 is applied as the ya-te signal to gated switches 160 and 164. When the gate signal is logic high, the input -to the gated switch is transmitted to the output of -the gated switch.
~1 'I'he outputs o~ ga-ted switches 158 and 160 are coupled to ,one input of N~ND gate 172. rrhe other input to NAND gate 172 ~is provided via conductor 51 by the bit counter circuit such that l~this yate is only turned on af-ter ten data bits have been received.
I!TIIe output of NAND gate 172 is applied as one input to a negative :l control NAND yate 174. The other inputs to negative control , INAND gate 174 are provided by the channel enable logic clrcuit 60 of Figure 8 via conductor 63, and the output of NAND gate 166. The outputs of gated switches 162 and 164 are coupled . -27-¦Ito one input o~ a positive control N~ND gate 176. The other ~inputs of this positive~ control NAND gate are provided by the channel logic circuit 60 via conductor 63, the output o~ NAND
gate 166, and frorn the bit counter circuit 31 via conductor 51.
The outpu-t of negative control NA~D gate 174 is Qn in truth table 170 and is applied to output switch 34a and to NAND gate inverter 178. The output of posi-tive control NAND gate 176 is Qp in truth table 170 and is aE~plied to output switch 34b and to NAND gate in-verter 180.
lhe output switch 34a comprises a n-channel MOS transistor 184 while output switch 34b comprises p-channel MOS transistor 186 and n-channel MOS transistor 188. rrhe transmitted pulse V
can be applied to the electrode 18a via conductor 32 if the electrode has a prograr~ed positive polarity. This pulse is coupled to electrode 18a by capacitor 190.
¦ The operation o~ the output control lo~ic 52 in Figure 9 ~ 1 ¦¦can be hest explained by example. Assuming that electrode 18a l¦is to have a positive polarity, -then Qp is logic low and Qn :::`
is logic hicJh as defined by truth -table 170. Further, assume ¦Ithat monophasic capabllity is required such that the non-inverted ; IQ outpu-t of flip-Elop 148 in Figure 8 is logic high and the inverted ~) output is logic low. Recall that in the monophasic mode, these outputs wi.ll rernain constant. Finally, it is I I assumed that (a) bit counter circui-t 31 of Figure 2 has determined that ten data bits have been received such that a logic high is present, on conductor 51, and (b) the channel enable logic clrcuit 60 of Figure 8 has been enabled such that a logic high is present on conductor 63.

!l :

, -2~-:

166~
¦1 Under these conditions, the flip-flop 112 will have a ~¦ logic hic~h at its non-inverted Q output ana a loyic low at its inverted Q outpu-t. Further, the non-inverted Q output of I ~ flip-flo~ 113 will be logic low and the inverted Q output will be loyic high. Since the monophasic mode i5 programmed, ~ the non-inverted Q output of flip-flop 148 of E'igure 8 will ;1~ gate a logic higll through both gated switch 160 and gated switch I 164. Gated switclles 158 and 162 will not be enabled since the inverted Q OUtpllt of the flip-flop 14$ of Fiyure 8 is ¦ logic low. Since the bit counter circuit 31 has provided a logic high output via conductor 51, the output of NAND gate 172 is a logic low signal which is applied to negative I control MAND gate 174. The output of NAND gate 166 is logic high since electrode 18a is being programmed for receivlng the stimulation pulse.. Since the~channel enable loglc circuit of Figure 8 has been enabled, all the inputs to positive ;
control NAND gate 17~ are logic hiyh, and thus the output of this gate 1s logic low. Further, since a loyic low is present at nega-tive con-trol NAND c~a-te 174, the output of this yate I is logic high.
The logic low signal from positive control NAND gate 176 is applied to the p-channel MOS transistor 186 of output ¦ switch 3~b and to the NAND ya-te inverter 180. The output of the NAND gate is a logic hiyh which turns the n-channel klOS transistor 188 o~ switch 34b ON. Similarly, the loyic low ¦ signal turns ON p-cilannel MOS transis-tor 186. Since the output of the nega-tive control NAND yate 174 is logic high, the output of NAND yate invertor 178 is logic low. This Logic low signal hoLds n-channel MOS transistor 184 of switch 34a OFF, thereby disconnec-tiny the electro~le from ground 192. Therefore, since transistors 186 ~nd l88 of swi-tch 34b are ON and tra slstor 184 _~9 . . ~

" 12~66~
of switch 34a is OFF, the pulse Vp is applied through output I switch 34b and capacitor 190 to the electrode 18a.
l Assume IIOW that the physician requires the electrode 18a ; to have a negative or grounded polarity. In this case the output of neyative control NAND gate 174 is logic low and ; the output of positive control NAND gate 176 is logic high.
Therefore, n-channel ~IOS transistor 184 is ON, and the electrode 18a lS pulled to yround po-tential 192. No-te that the stimulation pulse cannot be transmitted through output switch 34b since both p-channel ~10S transistor 186 and n-channel ~OS transistor ~88 are O~'F.
It should be noted that if the channel enable logic circuit I 60 is not enabled, as would occur if the proper channel has not been selected, four consecutive, identical data se~uences haven't been received, or an invalid electrode has been selected, a ~
loyic low is present on conductor 63. This signal causes both~ ¦
Qn and Qp to be logic high and thus -the electrode will be open.
This open condition will also occur if a logic;low is present on conductor 51, indicating that the bit counter 31 has not counted ten data bits.
¦ Finally, should the physician require biphasic stimulation in the example above wherein electrode 18a is positive the outputs oE the Elip-flop 148 of Figure 8 will alternate with ~¦ each stimulation pulse. This alternation causes gated switches 158 and 162 to be enabled each Lime the outputs of flip-~lop 148 in Figure 8 alterrlate. The outputs of the switches 158 and 162 is a locJic low signal which causes the outputs of the negative and posi-tive control NAND yates 174 and 176 to alternate witll each stimulation pulse. Therefore electrode ~` 18a will go from positive polar1ty to ground and back again during three stimulation cycles. This cyling will continue as long as the rnono/biphasic programminy data bit is loyic high.
.'- .

` I -30-.~ I
.

......... ..... . . .

25~66~
The other electrodes 18b-18d can be programmed in a similar manner. Therefore, it can be seen that the receiver circuitry of the present invention provides a unique electronic system wherein the implanted electrodes can be independently programmed by the physician. In particular, each electrode is capable of dynamically assuming a positive, ne~ative or open circuit status any time after implantation. This flexibility gives the physician an improved opportunity -to a-ttain a desired result wlth less inconvenience to the patient.
A]thouclh the preferLed embodiment is shown to have four electrodes and ten data bits, it should be recognized that this ¦! should not be considered limiting. Any number of data bits and electrodes may be utilized.
The ins-tant invention thus provides an efficient tissue stimulation system for controlling nervous or muscular disorders. ¦
In particular, the system can be used to stimulate the cervical area of the spinal cord, the brain, the cerebellum or the individual nerve fibers or bundles thereof to elicit motor, sensorv, neuroloaic, ~hysiologic or psichological responses.
Alternatively, the system may be used to control muscle disorders, such as heart ailments. It is also envisioned that this system ¦I be utilized whenever s-timulation is re~uired for any other j therapeutic reason.
It is anticipated that developments by the meclical community I Will enable measuremerlt of certain physiologi.cal parameters to ¦ determine the optimum stimulation parameters. The instant inven-i~,tion includes the concept of incorporating measurement circuitry into the implant for telemetry to assist in determining the best ;I therapeutic regimen. The invention further includes incorporation j of a microprocessor or logic clrcuitry into the implant to automatically reprogram stimula-tion parameters.

~`~ .

. 11

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. An electronic tissue stimulator system, comprising:
at least three electrodes to be implanted adjacent tissue to be stimulated in a patient;
transmitting means for transmitting stimulation pulses for stimulating said electrodes and programming data defining which of said electrodes are to be stimulated and the electrical polarity of said electrodes relative to one another; and receiving means to be surgically implanted within said patient for receiving said stimulation pulses and said programming data, and for delivering the energy of said stimulation pulses to said electrodes in said polarity as defined by said programming data.

2. An electronic tissue stimulator system as defined in claim 1 wherein said tissue to be stimulated is nerve tissue.

3. An electronic tissue stimulator system as defined in claim 1 wherein said tissue to be stimulated is muscle tissue.

4. An electronic tissue stimulator system as defined in claim 1 wherein said programming data is transmitted as a modulated signal on a carrier wave, said carrier wave being transmitted in bursts to define said stimulation pulses.

5. An electronic tissue stimulator system as defined in claim 4 wherein the parameters of said bursts can be varied by said transmitting means such that said stimulation pulses have different pulse parameters.

6. An electronic tissue stimulator system as defined in claim 4 wherein said receiving means includes detector means to demodulate said stimulation pulses from said carrier wave.

7. An electronic tissue stimulator system as defined in claim 6 wherein said receiving means includes logic converter means for separating said programming data from said stimulation pulses.

8. An electronic tissue stimulator system as defined in claim 1 wherein said receiving means further includes error detection means for comparing consecutive sequences of said programming data and controlling delivery of said energy of said stimulation pulses to said electrodes as a function of said comparison, said delivery of energy defining a stimulation mode.

9. An electronic tissue stimulator system as defined in claim 8 wherein said energy is delivered to said electrodes after a predetermined number of consecutive, identical sequences of said programming data are received by said receiving means.

10. An electronic tissue stimulator system as defined in claim 8 wherein said receiving means further includes a voltage storage means for storing the steady-state energy derived from said stimulation pulses.

11. An electronic tissue stimulator system as defined in claim 10 wherein said receiving means further includes a loss of voltage comparator means which continuously compares the energy in said voltage storage means with a predetermined voltage to control said error detection means.

12. An electronic tissue stimulator system as defined in claim 11 wherein said loss of voltage comparator means resets said error detection means when said energy in said voltage storage means is less than said predetermined voltage, said reset serving to return the system to a programming mode.

13. An electronic tissue stimulator system as defined in claim 8 wherein said receiving means further includes a channel enable means controlled by said programming data and said error detection means for preventing energization of said electrodes until said error detection means determines that a predetermined number of consecutive, identical sequences of said programming data have been received.

14. An electronic tissue stimulator system as defined in claim 13 wherein four consecutive, identical sequences of said programming data must be received to enable said error detection means.

15. An electronic tissue stimulator system as defined in claim 13 wherein said receiving means includes two redundant receivers controlled by said channel enable means, said channel enable means preventing energization of said electrodes until one of said receivers has been selected for operation.

16. An electronic tissue stimulator system as defined in claim 13 wherein said channel enable means further prevents energization of said electrodes if an invalid electrode pro-gramming combination is defined in said programming data.

17. An electronic tissue stimulator system as defined in claim 13 wherein said receiving means further includes a memory means for storing said programming data.

18. An electronic tissue stimulator system as defined in claim 17 wherein said memory means is volatile.

19. An electronic tissue stimulator system as defined in claim 17 wherein said memory means is non-volatile.

20. An electronic tissue stimulator system as defined in claim 19 wherein said receiving means is powered by an internal energy source.

21. An electronic tissue stimulator system as defined in claim 20 wherein said receiving means is powered by a combination of said internal energy source and by the energy trans-mitted by said transmitting means.

22. An electronic tissue stimulator system as defined in claim 17 wherein said receiving means further includes a mono/
biphasic control means connected to said memory means for controlling the relative polarity of said stimulated electrodes during application of consecutive stimulation pulses to said electrodes.

23. An electronic tissue stimulator system as defined in claim 17 wherein said receiving means further includes an out-put control logic means connected to said memory means for controlling delivery of said stimulation pulses to said elec-trodes.

24. An electronic tissue stimulator system as defined in claim 23 wherein said output control logic means is controlled by said channel enable means.

25. An electronic tissue stimulator system as defined in claim 23 wherein said output control logic means is connected to a plurality of output switches, said output switches being controlled by said programming data to deliver said stimulation pulses to said electrodes.

26. An electronic tissue stimulator system as defined in claim 25 wherein said receiving means further includes delay means for controlling said output control logic means to delay the application of said stimulation pluses to said output switches.

27. An electronic tissue stimulator system as defined in claim 26 wherein said receiving means includes clock circuit means for controlling said delay means and for applying said programming data to said memory means, the period of said delay means being at least equal to the period of said programming data sequence such that said stimulation pulses are not applied to said output switches until after said programming data sequence has been store in said memory means.

28. An electronic tissue stimulator system as defined in claim 1 wherein said receiving means may be powered by the energy transmitted by said transmitting means.

29. An electronic tissue stimulator system as defined in claim 28 wherein said receiving means further includes memory means for storing said programming data.

30. An electronic tissue stimulator system as defined in claim 22 wherein said receiving means further includes a voltage storage means for storing the steady-state energy derived from said stimulation pulses, said voltage storage means being connected to said memory means for retaining said programming data in said memory means between reception of said stimulation pulses.

31. An electronic tissue stimulator system as defined in claim 1 wherein said receiving means includes a mono/biphasic control means for controlling the polarity of said stimulated electrodes during application of consecutive stimulation pulses to said electrodes.

32. An electronic tissue stimulator system as defined in claim 31 wherein said mono/biphasic control means causes the relative polarity of said stimulated electrodes to remain constant during application of consecutive stimulation pulses, said operation defining a monophasic mode. ::

33. An electronic tissue stimulator system as defined in claim 31 wherein said mono/biphasic control means causes the relative polarity of said stimulated electrodes to alternate during application of consecutive stimulation pulses, said operation defining a biphasic mode.

34. An electronic tissue stimulator system as defined in claim 31 wherein said mono/biphasic control means is controlled by said programming data.

35. A method of setting and resetting an electronic tissue stimulator system, comprising at least three electrodes, which has been surgically implanted in a patient, comprising:
transmitting first programming data, defining which of said electrodes will be stimulated and the electrical polarity of said electrodes relative to one another, to said receiving means to produce a response;
transmitting second programming data, defining a new combination of said electrodes to be stimulated or a new polarity of said stimulated electrodes, to said receiving means to produce a response.