Method and device for detecting a neural response in a neural measurement

• US 10,426,409 B2
• Filed: 11/22/2014
• Issued: 10/01/2019
• Est. Priority Date: 11/22/2013
• Status: Active Grant

• Current Assignee: Saluda Medical Pty Ltd.
• Original Assignee: Saluda Medical Pty Ltd.
• Inventors: Single, Peter Scott Vallack
• Primary Examiner(s): Hindenburg, Max F
• Application Number:
  US15/037,038
• Publication Number:
  US 20160287182A1
• Time in Patent Office: 1,774 Days
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/4848 Monitoring or testing the effects of treatment, e.g. of medication
• CPC Class Codes: A61B 5/6846 specially adapted to be brought in contact with an internal body part, i.e. invasive
• CPC Class Codes: A61B 5/6877 Nerve
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7246 using correlation, e.g. template matching or determination of similarity
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• CPC Class Codes: A61N 1/36071 Pain
• CPC Class Codes: A61N 1/36139 with automatic adjustment
• CPC Class Codes: G06F 2218/00 Aspects of pattern recognition specially adapted for signal processing

Abstract

A method for processing a neural measurement obtained in the presence of artifact, in order to detect whether a neural response is present in the neural measurement. A neural measurement is obtained from one or more sense electrodes. The neural measurement is correlated against a filter template, the filter template comprising at least three half cycles of an alternating waveform, amplitude modulated by a window. From an output of the correlating, it is determined whether a neural response is present in the neural measurement.

Claims

1. A method for processing a neural measurement obtained in the presence of artifact, in order to detect whether a neural response is present in the neural measurement, the method comprising:

obtaining a neural measurement from one or more sense electrodes, the neural measurement being obtained in the presence of artifact;

correlating the neural measurement against a filter template, the filter template comprising at least three half cycles of an alternating waveform, amplitude modulated by a window; and

determining from an output of the correlating whether a neural response is present in the neural measurement.

2. The method of claim 1 wherein the window comprises a triangular window.

3. The method of claim 2 wherein the triangular window is a standard triangular window of length L comprising coefficients w(n) as follows:

4. The method of claim 2 wherein the triangular window is a Bartlett window in which samples 1 and L are zero.

5. The method of claim 1 wherein the window comprises one of a Hanning window, a rectangular window or a Kaiser-Bessel window.

6. The method of claim 1 wherein the window comprises one or more basis functions derived from a sinusoidal binomial transform.

7. The method of claim 1 wherein the filter template comprises four half-cycles of an alternating waveform.

8. The method of claim 1 wherein the filter template comprises half cycles of a sine wave, modified by being amplitude modulated by the window.

9. The method of claim 1 wherein the filter template comprises half cycles of a cosine wave, modified by being amplitude modulated by the window.

10. The method of claim 1 wherein only a single point of the correlation is calculated.

11. The method of claim 10 wherein the single point of the correlation is calculated at a predefined optimal time delay.

12. The method of claim 11, further comprising determining the optimum time delay when a signal to artifact ratio is greater than one, at which a first or single point of the cross-correlation between the neural measurement and the filter template should be produced, by:

at an approximate time delay between the neural response and the filter template, computing real and imaginary parts of the fundamental frequency of the DFT of the neural measurement;

calculating a phase defined by the real and imaginary parts;

relative to a fundamental frequency of the template, calculating the time adjustment needed to change the calculated phase to π

/2; and

defining the optimum time delay as being the sum of the approximate time delay and the time adjustment.

13. The method of claim 11, wherein the optimum time delay is recalculated prior to every attempted detection of a neural response.

14. The method of claim 11, wherein the optimum time delay is recalculated in response to a detected change in the user'"'"'s posture.

15. An implantable device for processing a neural measurement obtained in the presence of artifact, in order to detect whether a neural response is present in the neural measurement, the device comprising:

measurement circuitry for obtaining a neural measurement from one or more sense electrodes, in the presence of artifact; and

a processor configured to correlate the neural measurement against a filter template, the filter template comprising at least three half cycles of an alternating waveform, amplitude modulated by a window; and

the processor further configured to determine from an output of the correlating whether a neural response is present in the neural measurement.