Multi-electrode spinal cord stimulation therapy
A device used for neurostimulation includes a plurality of electrodes. In order to improve therapeutic efficacy when using a group of N electrodes equal to or larger than 3, the device is configured to deliver a number of N+1 electrical phases during one cycle via the electrodes such that during N electrical phases of the cycle each electrode of the group delivers alternating a therapeutic electric phase and a number of N−1 charge balancing electric phases. One electrode of the group delivers its specific therapeutic electric phase and the other electrodes of the group deliver a charge balancing phase having an opposite polarity of the therapeutic electric phase delivered, and such that during an additional electrical phase each electrode of the plurality of electrodes delivers an electrical phase with an amplitude that establishes charge neutrality for residual charge on each respective electrode based on phases of the N other electrical.
1 . A device for neurostimulation ( 100 ) of a patient's body, wherein the device comprises a plurality of electrodes ( 102 . a , 102 . b , 102 . c , 102 . d , 200 . a , 200 . b ), wherein the number of the plurality of electrodes is Z, wherein a group of N electrodes ( 102 . a , 102 . b , 102 . c ) of the plurality of electrodes is equal to or larger than 3, wherein the device is configured to deliver a number of N+1 electrical phases during one cycle via the plurality of electrodes such that:
(a) during N electrical phases of the cycle each electrode of the group delivers alternating a therapeutic electric phase and a number of N−1 charge balancing electric phases, wherein the therapeutic electric phase of one electrode has an amplitude I1, I2, . . . IN specific to this electrode, wherein during a time of one phase one electrode of the group delivers its specific therapeutic electric phase and the other electrodes of the group or of the plurality of electrodes deliver a charge balancing phase having a polarity being opposite to the polarity of the specific therapeutic electric phase delivered at the same time; and
(b) during an additional electrical phase each electrode of the plurality of electrodes delivers an electrical phase with an amplitude that establishes charge neutrality for residual charge on each respective electrode accumulated during the N electrical phases.
2 . The device of claim 1 , wherein the device is configured such that amount of the amplitudes of the charge balancing electric phases is the (N−1)th part or the (Z−1) th part of the amount of the specific amplitude of the specific therapeutic electric phase delivered at the same time during one of the N therapeutic electrical phases.
3 . The device of claim 1 , wherein the device is configured such that the amplitude of the specific therapeutic phase of each electrode of the group ( 102 . a , 102 . b , 102 . c ) is automatically adjusted using ECAP waveform measurement.
4 . The device of claim 3 , wherein the device is configured such that ECAP waveform measurement is provided using at least one auxiliary electrode ( 200 . a , 200 . b ) of the plurality of electrodes Z ( 102 . a , 102 . b , 102 . c , 102 . d , 200 . a , 200 . b ) different from the group of electrodes N ( 102 . a , 102 . b , 102 . c ).
5 . The device of claim 3 , wherein the device is configured such that the ECAP waveform measurement is provided in predefined time intervals and/or if the patient's body position and/or activity change is detected by using an accelerometer contained within the device.
6 . The device of claim 1 , wherein the device is configured such that for assessing the amplitude of the specific therapeutic electric phase of each electrode of the group N ( 102 . a , 102 . b , 102 . c ) the specific activation threshold ( 1 ) for each electrode is determined, wherein the amplitude of one specific electrode of the group is a pre-defined part of the measured specific activation threshold of this electrode.
7 . The device of claim 1 , wherein during any of the N+1 phases, the device casing sources or sinks current to provide balance to the net currents of the active electrodes.
8 . The device of claim 1 , wherein the group of N electrodes of the plurality of electrodes is a subset of electrodes of the plurality of electrodes.
9 . A method for neurostimulation of a patient's body using a plurality of electrodes ( 102 . a , 102 . b , 102 . c , 102 . d , 200 . a , 200 . b ), wherein the number of the plurality of electrodes is Z, wherein a group of N electrodes ( 102 . a , 102 . b , 102 . c ) of the plurality of electrodes (N less than or equal to Z) is equal to or larger than 3, wherein a number of N+1 electrical phases during one cycle via the plurality of electrodes is delivered,
wherein during N electrical phases of the cycle each electrode of the group delivers alternating a therapeutic electric phase and a number of N−1 charge balancing electric phases, wherein the therapeutic electric phase of one electrode has an amplitude I1, I2, . . . IN specific to this electrode, wherein during a time of one phase one electrode of the group delivers its specific therapeutic electric phase and the other electrodes of the group or of the plurality of electrodes deliver a charge balancing phase having a polarity being opposite to the polarity of the specific therapeutic phase delivered at the same time; and
wherein during an additional electrical phase each electrode of the plurality of electrodes delivers an electrical phase with an amplitude that establishes charge neutrality for residual charge on each respective electrode accumulated during the N electrical phases.
10 . The method of claim 9 , wherein the amount of the amplitudes of the charge balancing electric phases is the (N−1)th part or the (Z−1)th part of the amount of the specific amplitude of the specific therapeutic electric phase delivered at the same time during one of the N electrical phases.
11 . The method of claim 9 , wherein the amplitude of the specific therapeutic phase of each electrode of the group ( 102 . a , 102 . b , 102 . c ) is automatically adjusted using ECAP waveform measurement.
12 . The method of claim 11 , wherein the ECAP waveform measurement is provided using at least one auxiliary electrode ( 200 . a , 200 . b ) of the plurality of electrodes ( 102 . a , 102 . b , 102 . c , 102 . d , 200 . a , 200 . b ) different from the group of electrodes ( 102 . a , 102 . b , 102 . c ).
13 . The method of claim 11 , wherein the ECAP waveform measurement is provided in predefined time intervals and/or if the patient's body position and/or activity change is detected by using an accelerometer contained within the device.
14 . The method of claim 9 , wherein for assessing the amplitude of the specific therapeutic phase of each electrode of the group ( 102 . a , 102 . b , 102 . c ) the specific activation threshold ( 1 ) for each electrode is determined, wherein the amplitude of one specific electrode of the group is a pre-defined part of the measured specific activation threshold of this electrode.
15 . A neurostimulation system, comprising:
at least one implantable lead comprising a plurality of electrodes; and
an implantable pulse generator (IPG) electrically coupled to the at least one implantable lead, wherein the IPG comprises control circuitry configured to generate a stimulation cycle comprising N+1 electrical phases, wherein N is a group of electrodes of the plurality of electrodes equal to or larger than 3;
wherein during N electrical phases of the cycle, the control circuitry causes each electrode of the group to deliver alternating a therapeutic electric phase and a number of N−1 charge balancing electric phases, wherein the therapeutic electric phase of one electrode has an amplitude specific to this electrode, and wherein during a time of one phase one electrode of the group delivers its specific therapeutic electric phase and the other electrodes of the group or of the plurality of electrodes deliver a charge balancing phase having a polarity being opposite to the polarity of the specific therapeutic electric phase delivered at the same time; and
wherein during an additional electrical phase, the control circuitry causes each electrode of the plurality of electrodes to deliver an electrical phase with an amplitude that establishes charge neutrality for residual charge on each respective electrode accumulated during the N electrical phases.
16 . The neurostimulation system of claim 15 , wherein the IPG further comprises sensing circuitry configured to record an evoked compound action potential (ECAP) via at least one of the plurality of electrodes, and wherein the control circuitry is configured to automatically adjust the amplitude of the therapeutic electric phase of at least one electrode of the group based on the recorded ECAP.
17 . The neurostimulation system of claim 16 , wherein the sensing circuitry is configured to record the ECAP using at least one auxiliary electrode of the plurality of electrodes that is distinct from the group of N electrodes delivering the therapeutic electric phases to minimize stimulation artifact.
18 . The neurostimulation system of claim 15 , wherein the IPG further comprises a plurality of bleeding resistors and a plurality of switches, and wherein during the additional electrical phase, the control circuitry is configured to operate the plurality of switches to connect the plurality of electrodes to the bleeding resistors to provide passive charge balancing.
19 . The neurostimulation system of claim 15 , wherein the control circuitry is configured to deliver the therapeutic electric phases with amplitudes established below a perception threshold of the patient to provide paresthesia-free neurostimulation.
20 . The neurostimulation system of claim 15 , further comprising an external programmer configured to wirelessly communicate with the IPG.