System and method for maintaining a distribution of currents in an electrode array using independent voltage sources

• US 8,055,337 B2
• Filed: 07/22/2009
• Issued: 11/08/2011
• Est. Priority Date: 07/24/2008
• Status: Active Grant

• Current Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Original Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Inventors: Moffitt, Michael, Peterson, David K. L.
• Primary Examiner(s): MANUEL, GEORGE C
• Application Number:
  US12/507,260
• Publication Number:
  US 20100023069A1
• Time in Patent Office: 839 Days
• Field of Search: 607/2
• US Class Current: 607/2
• CPC Class Codes: A61N 1/0551 Spinal or peripheral nerve electrodes
• CPC Class Codes: A61N 1/36071 Pain

Abstract

In one technique, a desired electrical current distribution on at least three active electrodes is selected. An electrical energy perturbation is generated on at least one electrode. A current-to-voltage relationship at each active electrode is estimated based on the energy perturbation. The current-to-voltage relationship for each active electrode takes into account current flow through other active electrodes. The voltage distribution necessary to achieve the desired current distribution is determined based on the estimated current-to-voltage relationship. Voltage-regulated energy is conveyed between the electrodes and tissue in accordance with the determined electrical voltage distribution. In another technique, an electrical energy perturbation on at least one of the electrodes is generated. Network resistances for each of at least three active electrodes are computed in response to the energy perturbation. The network resistances represent the resistances between the electrodes and common node to which the electrodes are connected.

Claims

1. A method of performing a medical procedure using a plurality of electrodes implanted within tissue of a patient, comprising:

selecting a desired electrical current distribution on at least three active ones of the plurality of electrodes;

generating an electrical energy perturbation on at least one of the plurality of electrodes;

estimating a current-to-voltage relationship at each of the active electrodes based on the generated electrical energy perturbation, wherein the current-to-voltage relationship for each of the active electrodes takes into account electrical current flow through others of the active electrodes;

determining an electrical voltage distribution on the active electrodes necessary to achieve the desired electrical current distribution on the active electrodes, wherein the electrical voltage distribution is based on the estimated current-to-voltage relationship; and

conveying voltage-regulated electrical energy between the active electrodes and the tissue in accordance with the determined electrical voltage distribution.

2. The method of claim 1, wherein the selection of the desired electrical current distribution comprising modifying a first desired relative electrical current distribution to a second desired relative electrical current distribution.

3. The method of claim 1, wherein the selection of the desired electrical current distribution comprises modifying the total current flowing through the active electrodes.

4. The method of claim 1, wherein the electrical energy perturbation is a voltage-regulated perturbation.

5. The method of claim 1, wherein the current-to-voltage relationship is estimated at a zero operating point of the voltage-regulated electrical energy.

6. The method of claim 5, wherein the electrical energy perturbation is generated in the absence of the conveyed voltage-regulated electrical energy.

7. The method of claim 6, wherein the current-to-voltage relationship is estimated at a non-zero operating point of the voltage-regulated electrical energy.

8. The method of claim 7, wherein the electrical energy perturbation is generated during the conveyance of the voltage-regulated electrical energy.

9. The method of claim 1, further comprising measuring one or more electrical parameters in response to generating the electrical energy perturbation, wherein the estimation of the current-to-voltage relationship at each of the active electrodes is based on the electrical parameter measurement.

10. The method of claim 9, wherein the one or more electrical parameters comprises a plurality of interelectrode impedances between the active electrodes.

11. The method of claim 10, wherein the estimation of the current-to-voltage relationship at each of the active electrodes comprises computing network resistances for each of the active electrodes based on the interelectrode impedances, wherein the network resistances represent the resistances between the respective active electrodes and a common node to which the active electrodes are connected in parallel.

12. The method of claim 11, wherein the electrode voltage distribution on the active electrodes are determined in accordance with the following equation:

13. The method of claim 9, wherein the one or more electrical parameters comprises a plurality of field potentials at the active electrodes.

14. The method of claim 13, wherein the one or more electrical parameters further comprises a plurality of monopolar impedances of the active electrodes.

15. The method of claim 14, wherein the electrode voltage distribution on the active electrodes are determined in accordance with the following equation:

16. The method of claim 1, wherein the tissue is spinal cord tissue.

17. The method of claim 1, wherein the electrical energy stimulates the tissue.

18. The method of claim 1, wherein the electrical energy is an electrical pulse waveform.

19. A neurostimulation system, comprising:

a plurality of electrodes configured for being placed in contact with tissue;

analog output circuitry configured generating an electrical energy perturbation on at least one of the plurality of electrodes; and

processing circuitry configured for selecting a desired electrical current distribution on at least three active ones of the plurality of electrodes, estimating a current-to-voltage relationship at each of the active electrodes based on the generated electrical energy perturbation, and determining an electrical voltage distribution on the active electrodes necessary to achieve the desired electrical current distribution on the active electrodes, wherein the electrical voltage distribution is based on the estimated current-to-voltage relationship, wherein the current-to-voltage relationship for each of the active electrodes takes into account electrical current flow through others of the active electrodes, and wherein the analog output circuitry is configured for conveying voltage-regulated electrical energy between the active electrodes and the tissue in accordance with the determined electrical voltage distribution.

20. The neurostimulation system of claim 19, wherein the processing circuitry is configured for selecting the desired electrical current distribution by modifying a first desired electrical current distribution to a second desired electrical current distribution.

21. The neurostimulation system of claim 19, wherein the processing circuitry is configured for selecting the desired electrical current distribution by modifying the total current flowing through the active electrodes.

22. The neurostimulation system of claim 19, wherein processing circuitry is configured for estimating the current-to-voltage relationship at a zero operating point of the voltage-regulated electrical energy.

23. The neurostimulation system of claim 22, wherein the analog output circuitry is configured for generating the electrical energy perturbation in the absence of the conveyed voltage-regulated electrical energy.

24. The neurostimulation system of claim 19, wherein the processing circuitry is configured for estimating the current-to-voltage relationship at a non-zero operating point of the conveyed voltage-regulated electrical energy.

25. The neurostimulation system of claim 24, wherein the analog output circuitry is configured for generating the electrical energy perturbation during the conveyance of the voltage-regulated electrical energy.

26. The neurostimulation system of claim 19, wherein the electrical energy perturbation is a voltage-regulated perturbation.

27. The neurostimulation system of claim 19, further comprising monitoring circuitry configured for measuring one or more electrical parameters in response to the analog output circuitry generating the electrical energy perturbation, wherein the processing circuitry is configured for estimating the current-to-voltage relationship at each of the active electrodes based on the electrical parameter measurement.

28. The neurostimulation system of claim 27, wherein the one or more electrical parameters comprises a plurality of interelectrode impedances between the active electrodes.

29. The neurostimulation system of claim 28, wherein the processing circuitry is configured for estimating the current-to-voltage relationship at each of the active electrodes by computing network resistances for each of the active electrodes based on the interelectrode impedances, wherein the network resistances represent the resistances between the respective active electrodes and a common node to which the active electrodes are connected in parallel.

30. The neurostimulation system of claim 29, wherein the processing circuitry is configured for determining the electrode voltage distribution on the active electrodes in accordance with the following equation:

31. The neurostimulation system of claim 27, wherein the one or more electrical parameters comprises a plurality of field potentials at the active electrodes.

32. The neurostimulation system of claim 31, wherein the one or more electrical parameters further comprises a plurality of monopolar impedances of the active electrodes.

33. The neurostimulation system of claim 32, wherein the processing circuitry is configured for determining the electrode voltage distribution on the active electrodes in accordance with the following equation:

34. The neurostimulation system of claim 19, wherein the electrical energy is tissue stimulating electrical energy.

35. The neurostimulation system of claim 19, wherein the electrical energy is an electrical pulse waveform.

36. The neurostimulation system of claim 19, further comprising an implantable neurostimulator containing the analog output circuitry, and an external controller containing the processing circuitry.