Method and apparatus for estimating neural recruitment

Patent metadata

Field	Value
Publication number	US-11445958-B2
Application number	US-202117355036-A
Country	US
Kind code	B2
Filing date	Jun 22, 2021
Priority date	May 13, 2011
Publication date	Sep 20, 2022
Grant date	Sep 20, 2022

Abstract

An implantable device for estimating neural recruitment arising from a stimulus, has a plurality of electrodes. A stimulus source provides stimuli to be delivered from the electrodes to neural tissue. Measurement circuitry obtains a measurement of a neural signal sensed at the electrodes. A control unit is configured to control application of a selected stimulus to neural tissue using the stimulus electrodes; and after the selected neural stimulus, apply a probe stimulus having a short pulse width. A remnant neural response evoked by the probe stimulus is measured; and the control unit estimates from the remnant neural response a neural recruitment caused by the selected neural stimulus.

First claim

The invention claimed is:

1. A method of applying stimulus to a tissue, the method comprising:
delivering, by a plurality of stimulus electrodes, a therapeutic pulse having a first pulse width,
delivering a probe pulse having a second pulse width after the therapeutic pulse, wherein the second pulse width is less than the first pulse width, and wherein the probe pulse evokes a neural response,
measuring, by one or more sense electrodes, the neural response evoked by the probe pulse;
determining a neural recruitment caused by the probe pulse based on the neural response; and
determining a parameter for a subsequent therapeutic pulse based on the neural recruitment.

2. The method of claim 1 , wherein the first pulse width is in a range of about 100-500 μs.

3. The method of claim 1 , wherein the determining the parameter comprises:
comparing the neural recruitment with a target neural recruitment;
deriving, using a controller, a command from the comparison; and
selecting, based on the command, the parameter for the subsequent therapeutic pulse.

4. The method of claim 1 , wherein measuring the neural response comprises:
settling measurement circuitry prior to the probe pulse, by connecting the one or more sense electrodes to the measurement circuitry to allow the measurement circuitry to settle towards a bio-electrically defined steady state;
recovering charge on the plurality of stimulus electrodes by short circuiting the plurality of stimulus electrodes to each other;
keeping the one or more sense electrodes disconnected from the measurement circuitry while delivering the probe pulse;
imposing a delay during which the plurality of stimulus electrodes are open circuited and the one or more sense electrodes are disconnected from the measurement circuitry and from the plurality of stimulus electrodes; and
measuring, after the delay, the neural response by connecting the one or more sense electrodes to the measurement circuitry.

5. The method of claim 1 , wherein the probe pulse is delivered after a refractory period of fibres recruited by the therapeutic pulse.

6. The method of claim 3 , wherein the selecting the parameter comprises refining a parameter for a previously delivered therapeutic pulse.

7. The method of claim 3 , wherein the target neural recruitment is a predetermined neural recruitment.

8. The method of claim 1 , wherein the probe pulse is delivered at least 1 ms after the end of the therapeutic pulse.

9. An implantable device for applying neural stimulus to neural tissue, the device comprising:
a plurality of electrodes including one or more nominal stimulus electrodes and one or more nominal sense electrodes;
a stimulus source for delivering stimulus pulses via the one or more stimulus electrodes to neural tissue;
measurement circuitry for obtaining a measurement of a neural signal sensed at the one or more sense electrodes; and
a control unit configured to:
control the stimulus source to deliver a therapeutic pulse to neural tissue via the one or more stimulus electrodes, the therapeutic pulse having a first pulse width;
control the stimulus source to deliver a probe pulse to the neural tissue having a second pulse width after the therapeutic pulse, wherein the second pulse width is less than the first pulse width, and wherein the probe pulse evokes a neural response;
control the measurement circuitry to measure the neural response evoked by the probe pulse;
determine a neural recruitment caused by the probe pulse based on the neural response; and
determine a parameter for a subsequent therapeutic pulse based on the neural recruitment.

10. The implantable device of claim 9 , wherein the first pulse width is in a range of about 100-500 μs.

11. The implantable device of claim 9 , wherein the control unit is configured to determine the parameter for the subsequent therapeutic pulse by:
comparing the neural recruitment with a target neural recruitment;
deriving a command from the comparison; and
selecting, based on the command, the parameter for the subsequent therapeutic pulse.

12. The implantable device of claim 9 , wherein the control unit is configured to control the stimulus source to deliver the probe pulse after a refractory period of fibres recruited by the therapeutic pulse.

13. The implantable device of claim 11 , wherein the control unit is configured to select the parameter by refining a parameter for a previously delivered therapeutic pulse.

14. The implantable device of claim 11 , wherein the target neural recruitment is a predetermined neural recruitment.

15. The implantable device of claim 9 , wherein the control unit is configured to control the stimulus source to deliver the probe pulse at least 1 ms after the end of the therapeutic pulse.

16. The implantable device of claim 9 , wherein the control unit is configured to control the measurement circuitry to measure the neural response by:
settling the measurement circuitry prior to the probe pulse by connecting one or more sense electrodes to the measurement circuitry to allow the measurement circuitry to settle towards a bio-electrically defined steady state,
recovering charge on the one or more stimulus electrodes by short circuiting the one or more stimulus electrodes to each other;
keeping one or more sense electrodes disconnected from the measurement circuitry while delivering the probe pulse,
imposing a delay during which the one or more stimulus electrodes are open circuited and one or more sense electrodes are disconnected from the measurement circuitry and from the stimulus electrodes; and
measuring, after the delay, the neural response by connecting one or more sense electrodes to the measurement circuitry.

17. A method of applying stimulus to a tissue, the method comprising:
delivering, by a plurality of stimulus electrodes, a plurality of therapeutic pulses having a first pulse width,
delivering a plurality of probe pulses having a second pulse width interleaved with at least some therapeutic pulses of the plurality of therapeutic pulses, wherein the second pulse width is less than the first pulse width, and wherein the plurality of probe pulses evoke neural responses,
measuring, after a probe pulse of the plurality of probe pulses and prior to a subsequent therapeutic pulse of the plurality of therapeutic pulses, a neural response evoked by the probe pulse of the plurality of probe pulses via one or more sense electrodes;
determining a neural recruitment caused by the probe pulse of the plurality of probe pulses based on the neural response; and
determining a parameter for the subsequent therapeutic pulse based on the neural recruitment.

18. The method of claim 17 , wherein the first pulse width is in a range of about 100-500 μs.

19. The method of claim 17 , wherein the determining the parameter comprises:
comparing the neural recruitment with a target neural recruitment;
deriving, using a controller, a command from the comparison; and
selecting, based on the command, the parameter for the subsequent therapeutic pulse.

20. The method of claim 19 , wherein the selecting the parameter comprises refining a parameter for a previously delivered therapeutic pulse.

21. The method of claim 19 , wherein the target neural recruitment is a predetermined neural recruitment.

22. An implantable device for applying neural stimulus to neural tissue, the device comprising:
a plurality of electrodes including one or more nominal stimulus electrodes an

Assignees

• Saluda Medical Pty Ltd

Inventors

• Parker John Louis
• Wah James Hamilton
• Karantonis Dean Michael
• Single Peter Scott Vallack

Classifications

• A61B5/388 Primary

  Nerve conduction study, e.g. detecting action potential of peripheral nerves · CPC title

• A61N1/36071

  Pain · CPC title

• A61B5/24 Primary

  Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof · CPC title

• A61N1/0551

  Spinal or peripheral nerve electrodes · CPC title

• A61N1/36135

  using physiological parameters · CPC title