Systems and methods for determining volume of activation for spinal cord and peripheral nerve stimulation

• US 20110066407A1
• Filed: 04/30/2010
• Published: 03/17/2011
• Est. Priority Date: 03/09/2006
• Status: Active Grant

• Current Assignee: Cleveland Clinic Foundation
• Original Assignee: Cleveland Clinic Foundation
• Inventors: Butson, Christopher R., Maks, Christopher B., McIntyre, Cameron C.
• Granted Patent: US 8,606,360 B2
• Time in Patent Office: Days
• US Class Current: 703/2
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/407 Evaluating the spinal cord A61B5/4896 takes precedence
• CPC Class Codes: A61B 5/7217 of noise originating from a therapeutic or surgical apparatus, e.g. from a pacemaker
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61N 1/0534 Electrodes for deep brain stimulation
• CPC Class Codes: G06F 30/23 using finite element methods [FEM] or finite difference methods [FDM]

Abstract

This document discloses, among other things, systems and methods for determining volume of activation for spinal cord stimulation (“SCS”) using a finite element model (FEM) circuit to determine a FEM of an implanted electrode and a spinal cord in which the electrode is implanted, a Fourier FEM solver circuit to calculate a potential distribution in the spinal cord using information from the FEM circuit and a capacitive component of at least one of the implanted electrode and the spinal cord, and a volume of activation (VOA) circuit to predict a VOA using the potential distribution and a neuron model.

Claims

1. A system comprising:

a finite element model (FEM) circuit, configured to determine a FEM that models an implanted electrode and a spinal cord in which the electrode is implanted;

a Fourier FEM solver circuit, communicatively coupled to the FEM circuit, configured to calculate a potential distribution in the spinal cord using information from the FEM circuit and a capacitive component of at least one of the electrode and the spinal cord; and

a volume of activation (VOA) circuit, communicatively coupled to the Fourier FEM solver circuit, configured to provide a predicted VOA using the potential distribution and a neuron model.

2. The system of claim 1, wherein the Fourier FEM solver circuit is configured to calculate the potential distribution in the spinal cord using information from the FEM circuit and the capacitive component of the electrode.

3. The system of claim 1, wherein the Fourier FEM solver circuit is configured to calculate the potential distribution in the spinal cord using information from the FEM circuit and the capacitive component of the spinal cord.

4. The system of claim 1, wherein the finite element model (FEM) circuit is configured to determine a FEM that models the electrode, the spinal cord, and an electrode-tissue interface;

and

wherein the Fourier FEM solver circuit is configured to calculate the potential distribution in the spinal cord using information from the FEM circuit and the capacitive component of at least one of the electrode, the spinal cord, and the electrode-tissue interface.

5. The system of claim 4, wherein the Fourier FEM solver circuit is configured to calculate the potential distribution in the spinal cord using information from the FEM circuit and the capacitive component of the electrode-spinal cord interface.

6. The system of claim 4, wherein the electrode-spinal cord interface includes an encapsulation area around the electrode.

7. The system of claim 1, wherein the Fourier FEM solver circuit is configured to calculate the potential distribution in the spinal cord in both time and space.

8. The system of claim 1, wherein the Fourier FEM solver circuit is configured to:

separate a stimulus waveform into frequency components;

obtain a solution of a Poisson equation at at least one frequency component with a stiffness matrix (σ

+iω

), wherein the stiffness matrix is representative of a capacitive component of at least one of the electrode and the spinal cord; and

use the solution to reassemble the stimulus waveform.

9. The system of claim 1, wherein the VOA circuit is configured to interpolate the potential distribution onto a plurality of model axons.

10. The system of claim 1, wherein the VOA circuit is configured to predict a VOA using multiple stimulation waveforms.

11. The system of claim 1, including an impedance circuit, coupled to the Fourier FEM solver circuit, configured to calculate an impedance by dividing a stimulation voltage by an integrated current density along an active electrode contact;

and

wherein Fourier FEM solver circuit is configured to calculate a potential distribution using the calculated impedance.

12. A hardware computer-readable medium, including instructions that, when performed by a computer, cause the computer to:

determine a finite element model (FEM) of an implanted electrode and a spinal cord in which the electrode is implanted;

calculate a potential distribution in the spinal cord using a Fourier FEM solver and a capacitive component of at least one of the electrode and the spinal cord; and

predict a volume of activation (VOA) using the potential distribution and a neuron model.

13. A system comprising:

means for determining a finite element model (FEM) of an implanted electrode and a spinal cord in which the electrode is implanted;

means for calculating a potential distribution in the spinal cord using a Fourier FEM solver and a capacitive component of at least one of the electrode and the spinal cord; and

means for predicting a volume of activation (VOA) using the potential distribution and a neuron model.

14. A computer-assisted method comprising:

determining, by a computer processor, a finite element model (FEM) of an implanted electrode and a spinal cord in which the electrode is implanted;

calculating, by the processor, a potential distribution in the spinal cord using a Fourier FEM solver and a capacitive component of at least one of the electrode and the spinal cord; and

predicting, by the processor, a volume of activation (VOA) using the potential distribution and a neuron model.

15. The method of claim 14, wherein the calculating the potential distribution in the spinal cord includes using the Fourier FEM solver and the capacitive component of the electrode.

16. The method of claim 14, wherein the calculating the potential distribution in the spinal cord includes using the Fourier FEM solver and the capacitive component of the spinal cord.

17. The method of claim 14, wherein the determining the FEM includes determining a FEM of the electrode, the spinal cord, and an electrode-spinal cord interface;

wherein the calculating the potential distribution in the spinal cord includes using the Fourier FEM solver and a capacitive component of at least one of the electrode, the spinal cord, and the electrode-spinal cord interface.

18. The method of claim 17, wherein the calculating the potential distribution in the spinal cord includes using the Fourier FEM solver and the capacitive component of the electrode-spinal cord interface.

19. The method of claim 17, wherein the using the capacitive component of the electrode-spinal cord interface includes using the capacitive component of an encapsulation layer around the electrode.

20. The method of claim 14, wherein the calculating the potential distribution in the spinal cord includes calculating the potential distribution in the spinal cord in both time and space.

21. The method of claim 14, wherein the calculating the potential distribution includes:

separating a stimulus waveform into frequency components;

obtaining a solution of a Poisson equation at at least one frequency component with a stiffness matrix (σ

+iω

), wherein the stiffness matrix is representative of a capacitive component of at least one of the electrode and the spinal cord; and

using the solution to reassemble the stimulus waveform.

22. The method of claim 14, wherein the using the potential distribution and the neuron model includes interpolating the potential distribution onto a plurality of model axons.

23. The method of claim 14, wherein the predicting the VOA includes using multiple stimulation waveforms.

24. The method of claim 14, including calculating an impedance by dividing a stimulation voltage by an integrated current density along an active electrode contact;

and

wherein the calculating the potential distribution includes using the calculated impedance.

25. A computer-implemented method comprising:

determining, by a processor, a finite element model (FEM) of an implanted electrode, a spinal cord in which the electrode is implanted, and an electrode-spinal cord interface;

calculating, by the processor, an impedance by dividing a stimulation voltage by an integrated current density along an active electrode contact;

calculating, by the precessor, a potential distribution in the spinal cord in both time and space using a Fourier FEM solver, using a capacitive component of at least one of the electrode, the spinal cord, and the electrode-spinal cord interface, and using the calculated impedance, wherein the calculating the potential distribution includes;

separating a stimulus waveform into frequency components;

obtaining a solution of a Poisson equation at at least one frequency component with a stiffness matrix (σ

+iω

), wherein the stiffness matrix is representative of a capacitive component of at least one of the electrode and the spinal cord; and

using the solution to reassemble the stimulus waveform;

predicting, by the processor, a volume of activation (VOA) using multiple stimulation waveforms;

using the potential distribution, and using a neuron model; and

wherein the predicting the VOA includes interpolating the potential distribution onto a plurality of model axons.

26. A computer-assisted method comprising:

obtaining volumetric imaging data representing an anatomic volume of a patient;

calculating at least one volume of influence of in a region in the anatomic volume, in which the calculating includes using finite element model (FEM) of an electrode and a spinal cord in the anatomic volume; and

determining a potential distribution in both time and space using a Fourier FEM solver to solve the FEM.