Method and apparatus for controlling a neural stimulus
First Claim
1. An automated method of controlling a neural stimulus, the method comprising:
- applying the neural stimulus to a neural pathway in order to give rise to an evoked action potential on the neural pathway, the stimulus being applied as defined by a set of parameter values;
measuring a neural compound action potential response evoked by the stimulus and deriving from the measured evoked response a feedback variable;
comparing the feedback variable to a therapy map, the therapy map defining a therapeutic relationship of control variable to feedback variable, and determining from the therapy map a required change in the control variable in order to improve alignment of the feedback variable with the therapy map;
altering one or more of the stimulus parameter values to effect the required change in the control variable; and
iteratively performing the applying, measuring, comparing and altering, in order to improve alignment of the feedback variable with the therapy map over time;
wherein the feedback variable is a type of measure of evoked response strength, and the control variable is a type of stimulus intensity, and the therapeutic relationship represents a locus defining a desired output measure of evoked response strength for a given input stimulus intensity, with the desired output measure of evoked response strength being defined in a manner which varies for varying stimulus intensity.
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Abstract
An implantable device applies and controls a neural stimulus. The device has a plurality of electrodes, and a stimulus source for providing a stimulus to be delivered from the electrodes to a neural pathway in order to evoke an action potential on the neural pathway, such as the spinal cord. A control unit controls application of a neural stimulus as defined by a set of parameter values and measures via measurement circuitry an evoked neural compound action potential response. The control unit determines from the measured evoked response a feedback variable, and compares it to a therapy map. The therapy map defines a therapeutic relationship of control variable to feedback variable. One or more of the stimulus parameter values are altered to effect the required change in the control variable. This process is performed iteratively to improve alignment of the feedback variable with the therapy map over time.
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Citations
18 Claims
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1. An automated method of controlling a neural stimulus, the method comprising:
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applying the neural stimulus to a neural pathway in order to give rise to an evoked action potential on the neural pathway, the stimulus being applied as defined by a set of parameter values; measuring a neural compound action potential response evoked by the stimulus and deriving from the measured evoked response a feedback variable; comparing the feedback variable to a therapy map, the therapy map defining a therapeutic relationship of control variable to feedback variable, and determining from the therapy map a required change in the control variable in order to improve alignment of the feedback variable with the therapy map; altering one or more of the stimulus parameter values to effect the required change in the control variable; and iteratively performing the applying, measuring, comparing and altering, in order to improve alignment of the feedback variable with the therapy map over time; wherein the feedback variable is a type of measure of evoked response strength, and the control variable is a type of stimulus intensity, and the therapeutic relationship represents a locus defining a desired output measure of evoked response strength for a given input stimulus intensity, with the desired output measure of evoked response strength being defined in a manner which varies for varying stimulus intensity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. An implantable device for controllably applying a neural stimulus, the device comprising:
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a plurality of electrodes including one or more nominal stimulus electrodes and one or more nominal sense electrodes; a stimulus source for providing a stimulus to be delivered from the one or more stimulus electrodes to a neural pathway in order to give rise to an evoked action potential on the neural pathway; measurement circuitry for recording a neural compound action potential signal sensed at the one or more nominal sense electrodes; and a control unit configured to; control application of a neural stimulus as defined by a set of parameter values; measure via the measurement circuitry a neural compound action potential response evoked by the stimulus; determine from the measured neural compound action potential response a feedback variable; compare the feedback variable to a therapy map, the therapy map defining a therapeutic relationship of control variable to feedback variable; alter one or more of the stimulus parameter values to effect a required change in the control variable, and iteratively perform the applying, measuring, comparing and altering, in order to improve alignment of the feedback variable with the therapy map over time; wherein the feedback variable is a type of measure of evoked response strength, and the control variable is a type of stimulus intensity, and the therapeutic relationship represents a locus defining a desired output measure of evoked response strength for a given input stimulus intensity, with the desired output measure of evoked response strength being defined in a manner which varies for varying stimulus intensity.
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Specification