Method for optimizing search for spinal cord stimulation parameter settings

• US 20050209655A1
• Filed: 12/30/2004
• Published: 09/22/2005
• Est. Priority Date: 02/04/2002
• Status: Active Grant

• Current Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Original Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Inventors: Thacker, James R., Woods, Carla M., Bradley, Kerry, King, John D.
• Granted Patent: US 7,881,805 B2
• Time in Patent Office: Days
• US Class Current: 607/48
• CPC Class Codes: A61N 1/0551 Spinal or peripheral nerve electrodes
• CPC Class Codes: A61N 1/36071 Pain
• CPC Class Codes: Y10S 128/92 Computer assisted medical diagnostics

Abstract

Methods for selecting stimulation parameter sets guide a clinician towards an effective set(s) of stimulation parameters. The clinician first evaluates the effectiveness of a small number of trial stimulation parameters sets from a Measurement Table comprising for example, four stimulation parameter sets, measuring the perception threshold and maximum threshold levels. The maximum comfortable step size and desired field shift resolution are determined, and are used along with the measured threshold levels to determine an appropriate step size to use in the current steering process. In order to maintain paresthesia at a relatively constant level during the steering process, a Superposition Equalization (SEQ) algorithm is used to compensate for the physical characteristics of the lead array, i.e., electrode separation and size. A multiplier is determined and a modifying function is used to apply this multiplier to the electrode energy output during transition to maintain a relatively constant current density.

Claims

1-15. -15. (canceled)

16. A method for determining a step size between a first combination of programmable stimulating electrodes producing a first electric field defined by a first set of stimulation parameters and a second combination of programmable stimulating electrodes producing a second electric field defined by a second set of stimulation parameters, the electrodes being positioned on one or more implanted leads that deliver stimulation pulses from a pulse generator, the step size determining a shift in electric field, comprising:

determining a maximum comfortable step size;

determining a desired electric field shift resolution;

selecting a step size between the maximum comfortable step size and the desired electric field shift resolution.

17. The method according to claim 16, wherein the desired electric field shift resolution is the minimum programmable amplitude step size of a spinal cord stimulator.

18. The method according to claim 16, wherein the maximum comfortable step size is determined to be about 100 nC/pulse.

19. The method according to claim 16, wherein the maximum comfortable step size is determined by measurement prior to steering.

20. The method according to claim 16, wherein a relatively smaller step size is selected if a patient reports that a stimulation parameter set is effective, and a relatively larger step size is selected if the patient reports that a stimulation parameter set is not effective.

21. The method according to claim 16, wherein a current steering table is created having the selected step size.

22. The method according to claim 16, wherein a steering table stored in memory having the selected step size is selected.

23. A method for steering current between electrodes positioned on one or more implanted leads that deliver stimulation pulses from a pulse generator, comprising:

measuring a perception threshold and a maximum threshold for at least two trial stimulation parameter sets;

determining a maximum comfortable step size;

determining a minimum programmable step size; and

selecting a step size to be applied during a transition of stimulation between two or more electrodes;

wherein

the step size is between the maximum comfortable step size and the minimum programmable step size; and

the step size is variable and based upon the measured thresholds.

24. The method according to claim 23, further comprising:

determining the most effective trial stimulation parameter set; and

wherein selecting a step size comprises;

selecting a relatively smaller step size when the stimulation parameters are relatively close to the most effective trial stimulator parameter set; and

selecting a relatively larger step size when the stimulation parameters are relatively farther from the most effective trial stimulator set.

25. The method according to claim 23, wherein selecting a step size comprises:

selecting a relatively smaller step size when using at least one electrode from a portion of the lead that produced a relatively high perception threshold measurement; and

selecting a relatively larger step size when using at least one electrode from a portion of the lead that produced a relatively low perception threshold measurement.

26. The method according to claim 23, wherein selecting a step size comprises:

selecting a relatively smaller step size for electrodes designated as a cathodic electrodes; and

selecting a relatively larger step size for electrodes designated as anodic electrodes.

27. A method for maintaining paresthesia during a transition of stimulation between two or more electrodes positioned on one or more implanted leads that deliver stimulation pulses from a pulse generator comprising:

selecting a multiplier to be applied to each electrode providing stimulation during said transition;

creating an algorithm that uses the multiplier to determine the output of each electrode during the transition;

providing stimulation to each electrode at a magnitude determined by the algorithm.

28. The method according to claim 27, wherein the multiplier is determined by the lead type.

29. The method according to claim 27, wherein the multiplier is determined by a measurement of impedance.

30. The method according to claim 27, wherein the multiplier is determined by comparison of a measured dual cathode threshold to single cathode thresholds for two electrodes.

31. The method according to claim 27, wherein the multiplier is determined by a patient'"'"'s adjustments to stimulation during an unmodified transition.

32. The method according to claim 27, wherein the algorithm uses a modifying function to determine the output of each electrode during the transition.

33. The method according to claim 33, wherein a linear modifying function is used.

34. The method according to claim 33, wherein a non-linear modifying function is used.

35. The method according to claim 33, wherein stimulation is transitioned from a first electrode E₁ to a second electrode E₂ and wherein the algorithm defines outputs O_N when transitioning between E₁ and E₂ defined as:

O_N=A_N*(1−

X_N)*(M_N−

(2M_N−

2)*|0.5−

X_N|);

wherein N is 1 or 2;

O_N is the output defined by the algorithm for a particular electrode E_N;

A_N is a predetermined optimal stimulation level for electrode E_N;

M_N is the multiplier for electrode E_N; and

X_N is the relative output of electrode E_N compared to the total output, from 0 to 1.