Magnitude programming for implantable electrical stimulator

• US 6,587,724 B2
• Filed: 12/18/2000
• Issued: 07/01/2003
• Est. Priority Date: 12/17/1999
• Status: Expired due to Term

• Current Assignee: Boston Scientific Neuromodulation Corporation (Boston Scientific Corporation)
• Original Assignee: Advanced Bionics Corporation (Sonova Holding AG)
• Inventors: Mann, Carla M.
• Primary Examiner(s): Hoang, Tu Ba
• Application Number:
  US09/740,339
• Publication Number:
  US 20010034542A1
• Time in Patent Office: 925 Days
• Field of Search: 607/2, 607/45, 607/46, 607/56, 607/116, 607/137, 607/30, 607/9, 607/57, 607/62, 607/59, 607/99, 607/29, 600/378, 600/544
• US Class Current: 607/30
• CPC Class Codes: A61N 1/36164 Sub-threshold or non-excitatory signals non-excitatory signals to the heart A61N1/3628
• CPC Class Codes: A61N 1/36185 Selection of the electrode configuration
• CPC Class Codes: A61N 1/37235 Aspects of the external programmer
• CPC Class Codes: A61N 1/37241 providing test stimulations

Abstract

A neural stimulation system allows the magnitude of electrical stimuli generated by the system to be programmed to a desired level greater than or equal to a minimum perceived threshold and less than or equal to a maximum tolerable perceived threshold. The electrical stimuli are applied through selected groupings of individual electrode contacts of a multi-electrode-contact electrode array attached to pulse generation circuitry as either cathodes or anodes. The electrode array is implanted so that the individual electrode contacts are in contact with the body tissue to be stimulated. Stimulating electrical current pulses, defined by a prescribed set of stimulus parameters are generated and applied to the selected electrode contacts so as to flow from the anode electrodes to the cathode electrodes. The perceived magnitude of the applied stimuli is equalized in order to enable quick, automated, and/or interactive programming of the values of the stimulation parameters.

Claims

1. A method for operating an implantable neural stimulator, wherein the implantable neural stimulator includes a programmable pulse generator circuit housed within a sealed case, an electrode array connected to the neural stimulator, the electrode array having a plurality of electrode contacts, and wherein various combinations of the electrode contacts comprise sets of electrodes through which an electrical stimulus is applied, wherein the method comprises:

(a) measuring and recording at least one perception point for at least a selected subset of the sets of electrodes;

(b) estimating and recording perception points for unmeasured sets of electrodes; and

(c) mapping recorded and estimated values to magnitude levels for use with designated stimulation parameters in a set of stimulus parameters that are programmed into said implantable neural stimulator.

2. The method of claim 1 further including storing, calculating, and automatically adjusting magnitude levels when a given set of electrodes is selected as the electrode set through which an electrical stimulus is to be applied.

3. The method of claim 1 wherein mapping recorded and estimated values to magnitude levels comprises mapping the recorded and estimated values to unit-less magnitude numbers.

4. The method of claim 3 further including defining a set of unit-less magnitude numbers corresponding to each set of electrodes, a first magnitude number being mapped to a first stimulus current producing a minimum perception threshold level, and a second magnitude number being mapped to a second stimulus current producing a maximum tolerable threshold level.

5. The method of claim 4 wherein defining the set of unit-less magnitude numbers comprises defining a set of at least three unit-less magnitude numbers for each set of electrodes, the first magnitude number corresponding to the first stimulus current that produces the minimum perception threshold level, the second magnitude number corresponding to the second stimulus current that produces the maximum tolerable threshold level, and a third magnitude number corresponding to a third stimulus current greater than the first stimulus current and less than the second stimulus current that produces a comfortable threshold level.

6. The method of claim 4 wherein defining the set of unit-less magnitude numbers comprises defining a set of ten unit-less magnitude numbers for each set of electrodes, each unit-less magnitude number corresponding to a respective stimulus current, the respective stimulus currents ranging from the first stimulus current associated with the minimum perception threshold level and the second stimulus current associated with the maximum tolerable threshold level.

7. The method of claim 3 further including

applying a stimulus through a first set of electrodes having a magnitude defined by a selected magnitude number,

applying a stimulus through a second set of electrodes having a magnitude defined by the same selected magnitude number,

comparing the result of the stimulus applied through the first set of electrodes with the result of the stimulus applied through the second set of electrodes in a comparison test, and

selecting stimulus parameters for programming into the implantable neural stimulator as a function of the comparison test.

8. The method of claim 1 wherein estimating and recording perception points for unmeasured sets of electrodes comprises:

determining electrode sets for which perception points have not been measured;

estimating perception points for the unmeasured sets of electrodes by determining the perception points for the unmeasured sets of electrodes as a function of the perception points of the measured sets of electrodes; and

recording the estimated perception points.

9. The method of claim 8 further including calculating the perception points comprises extrapolating the perception points for the unmeasured sets of electrodes from the perception points from the measured sets of electrodes.

10. An implantable neural stimulator comprising:

(a) pulse generation circuitry housed within a sealed case, said pulse generation circuitry being adapted to generate electrical stimuli in accordance with programmed stimulus parameters;

(b) an implantable electrode array having a multiplicity of electrode contacts, wherein each of the multiplicity of electrode contacts is selectively connected to the pulse generation circuitry, and wherein the electrode contacts are grouped in selected electrode sets through which the electrical stimuli generated by the pulse generation circuitry is directed, each electrode set including a plurality of the electrode contacts, wherein one of the electrode contacts comprises the sealed case wherein the pulse generation circuitry is housed;

(c) a known threshold level for at least a plurality of the multiplicity of electrode contacts, where said known threshold levels are expressed in units of current or voltage; and

(d) an equalizer circuit that equalizes the threshold levels to unit-less magnitude levels.

11. The neural stimulation system of claim 10 wherein the equalizer circuit further estimates threshold levels for electrode contacts not initially known.

12. The neural stimulation system of claim 11 further wherein the neural stimulator automatically adjusts the magnitude of the stimulus applied through a selected electrode set to a value determined from the unit-less magnitude levels for the selected electrode set.

13. A system for determining an optimal set of stimulus parameters to be programmed into implantable pulse generation circuitry, the implantable pulse generation circuitry being housed within a sealed case, the pulse generation circuitry being adapted to generate electrical stimuli in accordance with programmed stimulus parameters;

and further wherein an electrode array having a plurality of electrode contacts is selectively connected to the pulse generation circuitry;

said system comprising;

at least one measured perception threshold for a selected set of the plurality of electrode contacts, where said at least one perception threshold is measured in units of current or voltage;

an equalizer that equalizes the at least one measured perception threshold for the selected set of electrode contacts to a unit-less magnitude level, and that estimates perception thresholds and corresponding magnitude levels for sets of electrode contacts where perception thresholds have not been measured; and

means for automatically adjusting the magnitude of the electrical stimuli applied by an implantable neural stimulator through a selected set of electrode contacts as a function of unit-less magnitude levels associated with the selected set of electrodes.

14. The system of claim 13 wherein the equalizer comprises:

memory circuitry wherein the perception threshold is stored;

mapping means for mapping the perception threshold of a given set of electrode contacts to a first number magnitude level, wherein when a stimulus having the first number magnitude level is selected to be applied to a selected set of electrode contacts, the set of electrode contacts receives a stimulus having a magnitude equal to the perception threshold.

15. The system of claim 14 wherein there are at least two perception thresholds for each selected set of the plurality of electrode contacts, one perception threshold comprising a minimum perception threshold level, and another perception threshold comprising a maximum tolerable threshold level;

and wherein the mapping means maps the minimum perception threshold level to the first number magnitude level, and maps the maximum tolerable threshold level to a second number magnitude level;

wherein the selected set of electrode contacts receives a stimulus having a magnitude equal to or near the minimum perception threshold level when the first number magnitude level is selected, and wherein the selected set of electrode contacts receives a stimulus having a magnitude equal to or near the maximum tolerable perception threshold level when the second number magnitude level is selected.

16. The system of claim 15 wherein the first number magnitude level comprises a low number, and the second number magnitude level comprises a high number, and further wherein a plurality of number magnitude levels exist greater than the low number and less than the high number, and wherein the pulse generation circuitry generates a stimulus having a magnitude greater than the minimum perception threshold level and less than the maximum tolerable threshold level when one of the number magnitude levels between the low and high numbers is selected as the magnitude level of the stimulus to be applied through a given set of electrode contacts.

17. The system of claim 16 wherein the low number comprises the number “

1”

, and the high number comprises the number “

10”

, and further wherein any of the number magnitude levels “

1”

through “

10”

is selected as the magnitude level of the stimulus that is to be applied through the selected set of electrode contacts.

18. The system of claim 17 wherein the number “

0”

is selected as a magnitude level, and wherein the magnitude of a stimulus having a magnitude level “

0”

is zero or off.

19. The system of claim 13 wherein at least one of the plurality of electrode contacts comprises a reference electrode contact located integrally with the sealed case of the implantable neural stimulator.

20. A neural stimulation system comprising:

implantable pulse generation circuitry housed within a sealed case, said pulse generation circuitry being adapted to generate a stimulus pulse in accordance with programmed stimulus parameters;

an electrode array having a multiplicity of electrode contacts, wherein each of the multiplicity of electrode contacts is selectively connected to the pulse generation circuitry;

wherein a minimum perception threshold and a maximum tolerable threshold for each of the multiplicity of electrode contacts is known or determinable, wherein said thresholds are measured in units of current or voltage; and

an equalizer that equalizes the minimum perception threshold and the maximum tolerable threshold to unit-less magnitude levels; and

wherein the pulse generation circuitry, upon command, automatically adjusts the magnitude of the stimulus pulse applied through a selected combination of the multiplicity of electrode contacts to a level referenced to the unit-less magnitude levels.

21. The neural stimulation system of claim 20 wherein the equalizer comprises:

memory circuitry wherein the minimum perception threshold and the maximum tolerable threshold are stored;

a mapping circuit that maps the minimum perception threshold of each electrode contact to a first number magnitude level and that maps the maximum tolerable threshold to a second number magnitude level, wherein when a stimulus having the first number magnitude level is selected to be applied to a selected combination of electrode contacts, the selected combination of electrode contacts receives a stimulus having a magnitude equal to or near the minimum perception threshold, and when a stimulus having the second number magnitude level is selected to be applied to a selected combination of electrode contacts, the selected combination of electrode contacts receives a stimulus having a magnitude equal to or near the maximum tolerable threshold.

22. The neural stimulation system of claim 21 wherein the first number magnitude level comprises a low number, and the second number magnitude level comprises a high number, and further wherein a plurality of levels exist greater than the low number and less than the high number, and wherein the implantable neural stimulator generates a stimulus having a magnitude greater than the minimum perception threshold and less than the maximum tolerable threshold when one of the levels between the low and high numbers is selected as the magnitude level of the stimulus to be applied to a selected combination of electrode contacts.

23. The neural stimulation system of claim 22 wherein the low number comprises the level “

1”

, and the high number comprises the level “

10”

, and further wherein any of the levels “

1”

through “

10”

is selected as the magnitude level of the stimulus applied through a selected combination of electrode contacts; and

wherein the implantable neural stimulator generates a stimulus having a magnitude greater than the minimum perception threshold measurement and less than the maximum tolerable threshold measurement when one of the levels “

2”

through “

9”

is selected as the magnitude level of the stimulus to be applied to the selected combination of electrode contacts.