(12) United States Patent
`(10) Patent N0.:
`US 6,473,653 B1
`
`Schallhorn et al.
`(45) Date of Patent:
`Oct. 29, 2002
`
`US006473653B1
`
`(54) SELECTIVE ACTIVATION 0F ELECTRODES
`WITHIN AN INPLANTABLE LEAD
`
`(75)
`
`Inventors: Rick S. Schallhorn, Lake Elmo; Gary
`W. King, Fridley; Gregory A.
`Hrdlicka, Plymouth, all of MN (US)
`
`.
`( * ) Notice:
`
`(73) Assignee: Medtronic, Inc., Minneapolis, MN
`(US)
`.
`.
`.
`.
`Subject. to any disclaimer, the term of this
`patent 15 extended or adjusted under 35
`U'S'C' 154(b) by0 days.
`(21) Appl. No“ 09/517’422
`(22)
`Filed:
`Mar. 2, 2000
`
`Related US. Application Data
`
`.
`.
`.
`.
`.
`(63) gsrrrats‘fimiElisa,atozfiitefigifsnr
`ation—in—part of application No. 08/627,576, filed on Apr. 4,
`1996, now abandoned.
`
`(51)
`
`Int. Cl.7 .................................................. A61N 1/05
`
`(52) US. Cl.
`
`........................ 607/116; 607/117; 600/393
`
`(58) Field of Search ................................. 607/116, 117,
`607/119, 122, 123, 129, 148; 600/373,
`374, 377, 378, 393
`
`EP
`WO
`
`FOREIGN PATENT DOCUMENTS
`0236513
`9/1987
`9519804
`7/1995
`
`OTHER PUBLICATIONS
`.
`.
`.
`Agnew et al., “Effects of Prolonged Electrical Stimulation of
`the Central Nervous System”, Chapter 9, pp. 227—252.
`Heinrich Bantli, Ph.D., et al., “Supraspinal Interactions
`Resulting from Experimental Dorsal Column Stimulation”,
`Journal of Neurosurgery, vol. 42, pp. 296—300 (1975).
`Jay D. Law, Spinal Stimulations: “Statistical Superiority of
`Monophasic Stimulation Nowly Separated, Longitudinal
`Bi oles Havin Rostral Cthodes”, Proc. of Amer. Soc.
`Stgrotatctic anfi Functional Neurosurgery. Appl. Neur-
`physiol 46, pp. 129—137 (1983).
`Holsheimer et al., “Contract Combinations in Epidural Spi-
`nal Cord Stimulation”, Stereotact Functional Neurosurgery,
`56, pp. 220—233 (1991).
`HOJSheimer .ee .1. “Home Geemee‘e Feeere Influence
`Epidural Spinal Cord Stimulation , Stereotact Functional
`Neurosurgery, 56, pp. 234—249 (1991).
`North et al., “Spinal Cord Stimulation for Chronic Intrac-
`table Pain: Superiority of Multi—Channel DeviCCS”, Pain, 44
`pp. 119—130 (1991).
`Barolat et al., “Multifactorial Analysis of Epidural Spinal
`Cord Stimulation”, Stereotact Funct Neurosurgery, 56, pp.
`77—103 (1991).
`
`.
`.
`(List continued on next page.)
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`Primary Examiner—Kennedy Schaetzle
`(74) Attorney, Agent, or Firm—Banner & Witcoff, Ltd.
`
`11/1975 Bowers
`3,920,024 A
`5/1976 Norman“
`39579036 A
`6/1985 Hildebrandt
`45247774 A
`13/13:: SBZEgzeppel
`4,570,230 2
`4,628,934 A * 12/1986 Pohndorf et a1.
`4:702:254 A
`10/1987 Zabara
`4,750,499 A
`6/1988 Hoffer
`4,867,164 A
`9/1989 Zabara
`4,877,032 A
`10/1989 Heinze et al.
`4,964,411 A
`10/1990 Johnson et 211.
`
`............. 607/27
`
`ABSTRACT
`(57)
`Percutaneously implantable multi-electrode lead adapted to
`interact with electrically excitable tissue. Electrodes are
`selected by a signal generator having a main controller that
`identifies via unique key values electrodes to be activated to
`stimulate electrically excitable tissue. Electrodes and their
`associated controllers are coupled such that relatively few
`wires are used to couple each electrode to the main control-
`ler.
`
`(List continued on next page.)
`
`15 Claims, 10 Drawing Sheets
`
`
`
`Nevro Corp.
`Ex. 1016
`
`US. Patent No. 8,650,747
`
`Nevro Corp.
`Ex. 1016
`U.S. Patent No. 8,650,747
`
`

`

`US 6,473,653 B1
`Page 2
`
`U.S. PATENT DOCUMENTS
`
`5/1991 Bach, Jr. et 211.
`5,018,523 A
`6/1991 Zabara
`5,025,807 A
`1/1992 Deletis
`5,081,990 A
`12/1992 Peckham et 211.
`5,167,229 A
`5/1994 Najafi et 211.
`5,314,458 A
`5/1994 Kovacs
`5,314,495 A
`7/1994 Kroll etal.
`5,325,870 A
`4/1995 Ayers et al.
`5,405,375 A *
`5/1995 Causey,III
`5,411,547 A
`5/1995 Hull et 211.
`5,417,719 A
`6/1995 Neubauer et 211.
`5,423,873 A
`7/1996 Schulman et 211.
`5,531,774 A
`1/1997 Ranger
`5,593,430 A
`5,824,029 A * 10/1998 Weijand et al.
`............. 600/547
`5,999,848 A * 12/1999 Gord et al. ............. 607/2
`
`............... 607/18
`6,163,723 A * 12/2000 Roberts et al.
`OTHER PUBLICATIONS
`
`................ 600/393
`
`Barolat et al., “Mapping of Sensory Responses to Epidural
`Stimulation of the Intraspinal Neural Structures in Man”,
`Journal of Neurosurgery, 78, pp. 233—239 (1993).
`
`Struijk et al., “Paraesthesia Thresholds in Spinal Cord
`Stimulation: A Comparison of Theoretical Results With
`Clinical Dates”, IEEE Transactions on Rehabilitation Engi-
`neering, V01. 1, N0. 3 (1993).
`
`Center for Integrated Sensors and Circuits, “Thin—Film
`Intracortical Recording Microelectrodes”, Neural Proshese
`Program, Quarterly Report No. 7 (Apr.—Jun. 1995).
`
`Struijk and Holsheimer, Transverse Tripolar Spinal Cord
`Stimulation : Theoretical Performance of Dual Channel
`
`System, Medical & Biological Engineering & Computing,
`pp. 273—279 (1996).
`
`Center for Integrated Sensors and Circuits, Thin—Film Intra-
`cortical Recording Microelectrodes, Neural Proshese Pro-
`gram, Quarterly Report No. 11 (Apr.—Jun. 1996).
`
`Center for Integrated Sensors and Circuits, “Micromachined
`Stimulating Electrodes”, Neural Proshese Program, Quar-
`terly Report No. 4 (Jul.—Sep. 1996).
`
`* cited by examiner
`
`

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`L4
`CH
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`cm
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`FIG.“
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` I
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`'I/I/i/I/i/I/i/a
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`[5
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`C15
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`FIG.I3
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`
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`P1+ ID1MODULATED ON P1)
`
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`'I/I/I‘l/Ii/I/Ia
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`f5
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`—~—..——
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`——
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`/5'
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`0/6
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`US 6,473,653 B1
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`IZO
`
`

`

`1
`SELECTIVE ACTIVATION OF ELECTRODES
`WITHIN AN INPLANTABLE LEAD
`
`2
`embodiment, a group of implantable electrodes is adapted to
`interact with the tissue. Amain cable extends from a first site
`
`US 6,473,653 B1
`
`This is a continuation-in-part of the earlier filed patent
`application Ser. No. 09/024,162 filed on Feb. 17, 1998, now
`US. Pat. No. 6,038,480 which is a continuation-in-part of
`patent application Ser. No. 08/627,576 filed on Apr. 4, 1996,
`now abandoned, for which priority is claimed. These appli-
`cations are incorporated herein by reference in their entire-
`ties.
`
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`
`This invention relates to an implantable system for stimu-
`lating electrically excitable tissue within a patient and more
`particularly relates to such a system in which the stimulating
`electrodes are selectable while minimizing the number of
`conductors within the lead.
`
`2. Description of the Related Art
`Often it
`is desirable with spinal cord or deep brain
`stimulation for pain relief or control of movement disorders
`to have many stimulation electrodes on a stimulation lead in
`order to place one or more cathodes and one or more anodes
`in optimal locations to produce benefits or minimize unde-
`sirable side effects. Implanted systems now use one to three
`leads and have between one and sixteen stimulation elec-
`
`trodes. Such systems typically must pass up to 20 milliam-
`peres of current or more, involving current densities of 10
`microcoulombs per square centimeter per phase or more. As
`a result, each electrode is connected to a sizable conductor
`in order to minimize energy losses due to impedance and to
`provide adequate strength to connect the wire to a power
`supply without substantial risk of breakage. Most current
`systems have the ability to program the polarity of each
`electrode. Due to size limitations and properties of
`conductors, it is difficult to have high reliability when there
`are eight, sixteen or more wires within a lead body that is
`implanted in a patient.
`Alead with twenty to fifty or more stimulation electrodes
`could be useful for some therapies. Optimal combinations of
`cathodes and anodes could be selected for each patient.
`However,
`the use of this many electrodes has not been
`feasible in the past because of the size limitations imposed
`by the need to have a sizable conductor connected to each
`electrode. The present invention is directed to solving this
`problem.
`A tripole lead is shown in PCT Publication No. WO95/
`19804 (Jul. 27, 1995), which is incorporated herein by
`reference in its entirety. However, such a lead lacks the
`ability to reprogram electrodes, and clinical benefit is criti-
`cally dependent on electrode positioning. US. Pat. Nos.
`5,713,922 and 5,925,070 disclose a system for adjusting the
`locus of excitation of tissue using two or three electrical
`leads, however, such systems are limited in the range of
`adjustment that can be made. Both of these patents are
`incorporated herein by reference in their entireties. This
`invention overcomes the disadvantages of the foregoing lead
`by allowing changes in an effective stimulation area after
`implant by programming.
`An additional shortcoming of prior art nuerostimulation
`paddle leads is that they require implantation via invasive
`surgery. Accordingly, there is a need for a percutaneous lead
`that does not require implantation via invasive surgery.
`SUMMARY OF THE INVENTION
`
`The invention is useful for interacting with electrically
`excitable tissue of a patient. According to a preferred
`
`the tissue. A source of data
`to a second site adjacent
`identifies one or more of the electrodes within the group, and
`a data conductor extends from the source of data to the
`
`5
`
`second site. An implantable controller is responsive to the
`data for gating one or more of the electrodes to the main
`cable.
`
`10
`
`The invention enables electrical signals to be transmitted
`between the first site and one or more selectable electrodes
`
`within the patient with a minimum number of conductors. As
`a result, the number of electrodes implanted in the patient
`can be substantially increased in order to provide improved
`therapeutic effects. By minimizing the number of
`conductors, reliability is improved.
`According to another embodiment of the invention, the
`electrodes include both recording electrodes and stimulating
`electrodes.
`
`In another embodiment, the present invention is a multi-
`electrode percutaneous lead that allows stimulation from any
`one of a number of electrodes with the use of three or fewer
`
`conductors to the signal generator.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`These and other advantages and features of the invention
`will become apparent upon reading the following detailed
`description and referring to the accompanying drawings in
`which like numbers refer to like parts throughout and in
`which:
`
`FIG. 1 is a top plan diagrammatic view of a preferred form
`of stimulation lead incorporating a stimulation assembly
`made in accordance with the present invention implanted
`within a patient and connected to a source of data;
`FIG. 2 is a side elevational view of the lead shown in FIG.
`
`1;
`
`FIG. 3 is a top plan diagrammatic view of a preferred form
`of recording assembly made in accordance with the present
`invention;
`FIG. 4 is a top plan diagrammatic view of modified form
`of lead in which the stimulation assembly of FIG. 1 and the
`recording assembly of FIG. 3 are combined using multiple
`controllers;
`FIG. 5 is a top plan diagrammatic view of another form
`of the invention employing multiple arrays of stimulation
`electrodes and an array of recording electrodes that are
`controlled by a single controller;
`FIG. 6 is a side elevational diagrammatic view of another
`form of the invention employing multiple electrodes on a
`nearly cylindrical lead;
`FIG. 7 is a diagrammatic end view of the lead shown in
`FIG. 6 and rotated slightly from the view shown in FIG. 6;
`FIG. 8 is an enlarged view of FIG. 7;
`FIG. 9 is a top plan diagrammatic view of another form
`of the invention in which the data conductor and one of the
`
`power conductors are multiplexed into a single line;
`FIG. 10 is a top plan diagrammatic view of another form
`of the invention employing multiple controllers wherein
`each controller controls one or more of the stimulation
`
`electrodes in the array;
`FIG. 11 is an exploded side elevational view of one of the
`stimulation electrodes of the lead shown in FIG. 10;
`FIG. 12 is a top plan diagrammatic view of another form
`of the invention employing multiple controllers wherein
`each controller controls one or more of the stimulation
`
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`US 6,473,653 B1
`
`3
`electrodes in the array and a power conductor is modulated
`with a data conductor;
`FIG. 13 is an exploded side elevational view of one of the
`stimulation electrodes of the lead shown in FIG. 12;
`FIG. 14 is a simplified diagrammatic view of a preferred
`form of multi-electrode stimulation lead coupled to a signal
`generator in accordance with the present invention.
`FIG. 15 is a more detailed view of a preferred embodi-
`ment of a multi-electrode stimulation lead similar to the lead
`of FIG. 14.
`
`FIG. 16 is a simplified circuit diagram of an electrode of
`the stimulation lead of FIG. 15.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`Referring to FIG. 1, a preferred form of flat paddle lead
`L1 suitable for implantation into a patient basically com-
`prises a stimulation assembly Sl that includes a controller
`C1 and an array of stimulating electrodes ASl. Lead L1 is
`implanted at a site 181 within a patient adjacent tissue to be
`stimulated. Array ASl includes fifty-five electrodes, such as
`flat electrodes 10—12, arranged in a rectangular grid and
`electrically insulated from each other. The top surface of
`array A81 is exposed to patient tissue at the surface of lead
`L1. Controller C1 is connected to a conductor ID1 over
`
`which data is provided, from a data source D1, as well as a
`cable CB1 comprising power conductors P1 and P2 for
`conducting stimulating current to electrode array ASl. P1
`and P2 are connected to a power source not shown. Con-
`troller C1 is coupled to each electrode in electrode array ASl
`with separate conducting wires. Data source D1 is located at
`a site 081 which could be located within the power source
`or at another location, usually subcutaneous. The data source
`may be a microprocessor including a memory for storing
`data that
`identifies electrodes to be activated and their
`
`polarities.
`The FIG. 1 embodiment is especially good for red skeletal
`muscle, since stimulation on such a muscle can only activate
`the muscle fibers directly under the cathode. Action poten-
`tials do not spread from muscle fiber to fiber, as they do in
`smooth muscle or cardiac muscle. Hence, a broad array of
`cathodes is useful to recruit many fibers of a red muscle.
`Referring to FIG. 2, lead L1 also may optionally include
`another array of stimulating electrodes AS2, including elec-
`trodes such as 15—17, that is arranged on a side of lead L1.
`The surface of the electrodes in array AS2 is exposed at the
`side of lead L1 to electrically stimulate tissue of a patient at
`site 181. Electrodes in array AS2 may be controlled by C1
`and/or a separate controller C2 as shown.
`Referring to FIG. 1, each electrode in array A81 and AS2
`is coupled to controller C1 and/or C2 via conductor wires.
`A signal is sent to controller C1 and/or C2 along conductor
`ID1 which identifies the electrodes to be activated. Control-
`
`lers C1 and C2 act as switching gates coupling power lines
`P1 and P2 to the activated electrodes in array A81 and AS2.
`Some activated electrodes may become cathodes (—) and
`other electrodes may become anodes (+). The plus signs and
`minus signs in FIG. 1 indicate electrodes which have been
`activated as anodes (+) and cathodes (—),
`respectively.
`Electrodes not chosen to be activated will be open circuit or
`will have a high impedance. The arrangement of anodes or
`cathodes on assembly Sl can be chosen by the patient or
`through investigation by clinicians to maximize the desired
`effects of stimulation, e.g., maximize pain relief, minimize
`spasticity, stop seizures, cause contraction of muscles, etc.,
`and also to minimize undesirable side effects.
`
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`4
`Still referring to FIG. 1, power conductors P1 and P2
`carry the stimulation current necessary in order to stimulate
`the electrically excitable tissue adjacent
`lead L1. For
`monopolar stimulation, a single one of conductors P1 and P2
`would suffice; but for bipolar stimulation, two power con-
`ductors (single channel), such as P1 and P2 are needed. For
`dual channel applications, three or four power conductors
`may be used. Fewer wires may suffice if the power signal is
`time division multiplexed.
`FIG. 9 illustrates an embodiment of the present invention
`having two conductors leading to lead L1. Conductors P1
`and ID1 of FIG. 1 are combined into a single conductor. The
`P1 and ID1 signals are modulated, thereby reducing the need
`for a third conductor. The modulation of the data signal of
`ID1 and the power signal of P1 or P2 may be accomplished
`by any number of modulation techniques including, but not
`limited to, Amplitude Modulation (AM), Frequency Shift
`Keying (FSK), Phase Shift Keying (PSK), pulse position
`timing and any combination thereof.
`Referring back to FIG. 1, each of electrodes in arrays A81
`and AS2 is between 1—6 mm in area, but other sizes also may
`be used. Typically, several neighboring electrodes are con-
`nected in parallel to have a combined surface area of 6—24
`mm2, but other sizes also may be beneficial. The electrodes
`in arrays A81 and AS2 are electrically conductive, and
`usually are made from a metal like platinum or iridium. In
`FIG. 1, four electrodes have been programmed to be anodes
`(+) and six electrodes have been programmed to be cathodes
`(-)~
`The invention is useful in connection with electrically
`excitable tissue which includes both neural
`tissue and
`
`muscle tissue. Neural tissue includes peripheral nerves, the
`spinal cord surface, the deep spinal cord, deep brain tissue
`and brain surface tissue. Muscle tissue includes skeletal
`
`(red) muscle, smooth (white) muscle, and cardiac muscle.
`FIG. 3 illustrates a preferred form of recording assembly
`R1 which includes a controller C2 and an array of recording
`electrodes RE1—RE5 electrically insulated from each other.
`Assembly R1 is implanted inside a patient at a site IS2.
`Controller C2 is provided with a conductor ID2 for trans-
`mitting data and a cable CB2 that includes power conductors
`P3 and P4, as well as an additional conductor RD1 used to
`transmit recorded and amplified tissue potentials received by
`one or more of conductors RE1—RE5. Conductor RD1 may
`be five separate conductors connected to electrodes
`RE1—RE5 or a single conductor on which potentials from
`electrodes RE1—RE5 are transmitted by time division mul-
`tiplex techniques executed by controller C2. Alternatively,
`controller C2 might activate combinations of electrodes
`RE1—RE5 as stimulating electrodes to provide stimulation
`of tissue.
`
`Recording assembly R1 can be used to record potentials
`in electrically excitable tissue. Controller C2 selects from
`among recording electrodes RE1—RE5, amplifies the signals
`received by the recording electrodes and sends the amplified
`signals over conductor RD1 to a recording instrument RC1.
`Controller C2 also could filter or otherwise process the
`signals. Instrument RC1 is located at another site, possibly
`OSl.
`
`Referring to FIG. 3, under each recording electrode
`RE1—RE5 is an electrical circuit consisting of an operational
`amplifier and a gating circuit to turn on or turn off the
`recording electrode. A recording electrode may be chosen
`with optimal signal strength and discrimination of the poten-
`tial of interest. Two or more electrodes may be connected
`together in parallel to lower impedance or may be used
`
`

`

`US 6,473,653 B1
`
`5
`differentially to better shape the recorded potential and
`remove noise signals. Alternatively, controller C2 may con-
`trol all signal conditioning functions and gating circuits,
`particularly if the dimensions of recording assembly R1 are
`small.
`
`Conductor ID2 is used to carry data from a data source,
`such as D1,
`to controller C2.
`In response to the data,
`controller C2 activates the desired electrodes and adjusts the
`amplification. Cable CB2 is used to bring power to control-
`ler C2. Conductor RD1 exits from the recording site 182 to
`bring the amplified recorded potentials to recorder RC1. The
`recording electrodes each typically have an impedance
`between 100,000 ohms and 1.5 megohms, but other imped-
`ances may be desirable.
`FIGS. 4 and 5 show the flexibility of controllers and
`arrays of stimulation electrodes and optional recording elec-
`trodes made in accordance with the invention. Referring to
`FIG. 4, a lead L2 may comprise stimulating assembly SI and
`optional recording assembly R1, as well as additional stimu-
`lating assemblies S2 and S3 that may be identical to assem-
`bly 81. Additional stimulating or recording assemblies may
`be added to SI by the practitioner during implant. Conductor
`RD2 carries recorded potentials to a recorder, such as RC1
`shown in FIG. 3. Conductor RD2 may be an extension of
`conductor RD1, or may contain additional data resulting
`from processing done in controller C1 of assembly 81. For
`the configuration shown in FIG. 4, controller C1 of assembly
`Sl may incorporate the functions of controllers C1 and C2
`described in connection with FIGS. 1 and 3. Alternatively,
`controllers C4 and CS may provide control to assemblies S2
`and S3 respectively. Power is furnished to assemblies S2 and
`S3 by power conductors P1 and P2. A conductor ID3
`communicates the data necessary to identify the stimulation
`electrodes within assembly S2 that need to be activated. A
`similar function is performed for assembly S3 by a data
`conductor ID4. Controller C1 processes the data on conduc-
`tor ID1 in order to provide the appropriate data for assem-
`blies S2 and S3 that is transmitted over conductors ID3 and
`
`ID4, respectively. With modulation of power signals on
`conductors P1 and P2, data conductors ID1, ID3 and ID4
`may be unnecessary.
`Referring to FIG. 5, a lead L3 carries a controller C3 that
`is connected to array A81 and an identical array AS2, as well
`as array AR1. Each of the recording electrodes in array AR1
`is connected to controller C3 by one of conductors
`RL1—RLS. Each of the stimulating electrodes on assembly
`A81 is connected to controller C3 by a cable CB6, which
`contains individual conductors connected separately to each
`of the electrodes in assembly ASl. Similarly, each of the
`stimulating electrodes in assembly AS2 is connected to
`controller C3 through a cable CB7. Controller C3 receives
`information on conductor ID1 which identifies the elec-
`trodes of assemblies A81 and AS2 which are to be activated,
`as well as the polarity of the electrodes. Controller C3
`activates the electrodes in assemblies A81 and AS2 in the
`same manner described in connection with controller C1 of
`FIG. 1.
`
`The potentials transmitted by each of conductors
`RL1—RLS are transmitted by controller C3 on a time divi-
`sion multiplex basis on output conductor RD2. RD2 may be
`connected to a recorder such as RC1 shown in FIG. 3.
`
`FIG. 6 illustrates a generally cylindrical lead L4 carrying
`a controller C4 and an assembly of twenty-two stimulating
`electrodes AS3, including cylindrical electrodes 20 and 21
`arranged as shown. Inside the body of lead L4 and mounted
`directly on electrodes 20 and 21 are corresponding electrical
`
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`
`circuits CT1 and CT2 (FIGS. 7 and 8). For stimulating
`assembly AS3, circuits CT1 and CT2 are electrical switches
`or gates which activate specified electrodes in the assembly
`in accordance with the data received on conductor ID1. If
`there is only one electrode at each longitudinal position of
`the lead, it could be a ring electrode. If there is more than one
`electrode at each longitudinal position, the electrodes at each
`longitudinal position could occupy equal sectors of the
`cross-section of lead L4. Then, by use of controller C4, only
`those electrodes nearest the excitable tissue could be used
`for stimulating or recording. A complex lead may be
`assembled in the operating room by plugging any number of
`cylindrical extensions onto lead L4 (FIG. 6).
`A recording assembly can be made in the same form as
`assembly AS3 shown in FIG. 6. In this case, the electrodes
`would perform the same recording function described in
`connection with FIG. 3. In such an embodiment, circuits
`CT1 and CT2 would be an amplifier and switchable gate that
`would transmit a tissue potential to controller C4.
`FIG. 10 is a top plan diagrammatic view of another
`embodiment of the invention employing multiple controllers
`wherein each controller controls one or more of the stimu-
`
`lation electrodes in the array. FIG. 10 illustrates a lead LS
`having a stimulation assembly SS that includes an array of
`controllers (not shown) and a corresponding array of stimu-
`lation electrodes ASS. Power conductors P1 and P2 and data
`
`signal ID1 connect to lead L1 similar to that of FIG. 1.
`Alternatively, as shown in FIG. 12, power conductor P1 may
`be modulated with data conductor ID1 using any number of
`modulation techniques thereby reducing the number of
`conductors to lead LS.
`
`Referring to FIG. 10, each stimulation electrode with in
`the array ASS has a corresponding controller which controls
`the operation of that electrode. Power signals P1 and P2 and
`data signal ID1 are provided to each of these individual
`controllers which in turn control the operation of the asso-
`ciated stimulation electrodes based on these signals. In such
`an embodiment, controller C1 (as shown in FIG. 1) would
`not be required. FIG. 11 is an exploded side elevational view
`of an individual controller CS and the associated stimulation
`electrode E5 of lead LS. Power lines P1 and P2 and data line
`
`ID1 run to each controller in lead LS including controller
`CS. Alternatively, as shown in FIG. 13, power conductor P1
`may be modulated with data conductor ID1 using any
`number of modulation techniques thereby reducing the
`number of conductors to lead controller CS. FIG. 11 depicts
`a typical electrode/controller pair combination of lead LS.
`Controller CS may be an integrated circuit (IC) and the
`conductors leading to controller CS may be wirebonded to
`controller CS. Each electrode/controller pair has a unique
`address such that data conductor ID1 may designate which
`electrodes are to be activated based on the address informa-
`
`tion carried by the data conductor ID1. For each electrode
`designated for activation, the electrode is designated as an
`anode (+) or a cathode (—). As another embodiment, con-
`troller CS may be positioned to control the operation of a
`number of electrodes. Controller CS may also be used to
`control recording electrodes.
`Each of assemblies ASl—AS3, ASS and AR1 may be
`silicon wafers, and thus rigid. Controllers C1—CS may be
`conventional microcontrollers capable of executing instruc-
`tions stored in memory. Other parts of leads L1—LS may be
`flexible and inert, or flexible and carry wires, such as
`assemblies ASl, AS2, and AR1 of FIG. 5. Flexible electrical
`circuits or ribbon cables also could be used to advantage.
`Leads L1—LS offer several advantages over known leads.
`One does not always know before implant what is the best
`
`

`

`US 6,473,653 B1
`
`7
`strategy for lead placement and electrode polarity. Leads
`L1—L5 allow the choice to be made later, and additional
`reprogramming at later dates, to give degrees of freedom in
`electrode position. It is sometimes useful to have five or
`more electrodes in a line (especially transverse to the spinal
`cord axis), so that two or three can be chosen at preferred
`medial/lateral positions. The preferred embodiments enable
`changes in effective stimulation area after implant by pro-
`gramming only.
`One key need for practitioners using spinal cord stimu-
`lation is to position one or more electrodes on the “physi-
`ological midline”. This means that pulses will give balanced
`effects, and not be biased unduly on one or the other side
`(near one or the other dorsal root). When using the location
`of the vertebral canal for lead placement, only 27% of the
`time is the paresthesia balanced (Barolat, G., Zeme, S. and
`Ketcik, B., Multifactorial analysis of epidural spinal cord
`stimulation, Stereotact. Funct. Neurosurg., 56 (1991)
`77—103. The preferred embodiments allow the “physiologi-
`cal midline” to be found by testing, and to be programmed
`accordingly.
`Recording of electrical signals is quite difficult, and very
`dependent on distance from the active tissue, direction of
`action potentials in axons, and especially on the area/
`impedance of the recording site (low impedance picks up
`potentials from larger distances, but signals are small). By
`picking the right locations of recording sites, and adding or
`subtracting neighboring site signals, the best signal can be
`obtained.
`
`Being able to select and activate electrodes from a large
`number of possible sites provided by the preferred embodi-
`ments is valuable in case any site becomes unusable due to
`mechanical/electrical problems, scar
`tissue, etc. A near
`neighboring site might give almost as useful a result.
`Currently the only way to select optimal electrode sites
`(beyond polarity choices) is by surgical positioning of the
`lead, which might be unreliable over time because position-
`ing was done with the patient in one body position, and can
`change by migration of the lead. There have been proposals
`for leads that can have configuration changes, but these
`proposals do not offer
`the advantage of the preferred
`embodiments.
`
`Advantageous uses for leads L1—L5 described in this
`specification include:
`a. Over or in motor cortex or cerebellar cortex, where
`there are somatotopic maps of the body, and where fine
`control of the loci of excitation can help affect
`the
`movements or control of various body parts;
`b. Over or in the sensory cortex, which also has a
`somatotopic map, so that paresthesia and/or motor
`effects can be adjusted to specific body parts;
`c. In the thalamus, where there is a three-dimensional
`body map, and where there are lamina of cells that
`might best be activated (or partly activated) using many
`contacts and programming.
`d. In deep tissue, where stimulation is advantageously
`achieved by cylindrical leads;
`e. Transversely and over the cauda equina (nerves in the
`spinal canal descending from the tip of the cord) to
`enable great selectivity of stimulation;
`f. In the cochlea, where there is insufficient space for
`many wires, but many channels are needed and where
`fine-tuning which sites along the cochlea get stimulated
`might lead to much better hearing;
`g. Over branches of motor nerves or large nerves,
`activate distinct fascicles; and
`h. In the retina, where if a patient has no light going to the
`back of the eye, the preferred embodiment could stimu-
`
`to
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`8
`late in neural patterns as if light were going there in
`focus and being perceived.
`The controller chips disclosed in this specification pref-
`erably are rigid, made of silicon, with a hermetically sealed
`cover. However, they may be quite small. Of course, the
`controller chips may be made of any other known, or later
`developed, material suitable for integrated circuits. All other
`parts of leads L1—L5 may be flexible.
`Another advantage of leads L1—L5 is that a number of
`recording sites could be programmed in parallel to constitute
`a stimulation site which generally requires a low impedance
`and larger surface area. Several stimulation sites may be
`programmed together to reduce the impedance.
`As disclosed in FIG. 14, another embodiment of the
`present
`invention is a percutaneous lead 100 having a
`plurality of electrodes 110-1 through 110-N (collectively
`referred to as 110) along the distal end 101 of lead 100. Each
`electrode 110 has a corresponding controller 115-1 through
`115-N (collectively referred to as 115) adjacent
`to and
`associated with each electrode 110. Each controller 115 is
`preferably coupled to signal generator 102 via power con-
`ductors 120 and 125, one conductor providing stimulation
`pulses and the other providing common ground. Controllers
`115 may be coupled to a main controller 103 via data
`conductor 130. Main controller 103 is preferably a
`microprocessor, which may be part of signal generator 102.
`Main controller 103 may identify an electrode, or electrodes,
`110 to provide electrical stimulation provided by signal
`generator 102. Each corresponding controller 115 may be
`uniquely identifiable such that a control signal from main
`controller 103 may identify the corresponding controller, or
`controllers, 115 to allow its associated electrode, or
`electrodes, 110 to deliver electrical stimulation. Cont