Method for automated analysis of submaximal F-waves

• US 20060217631A1
• Filed: 11/02/2005
• Published: 09/28/2006
• Est. Priority Date: 02/17/2004
• Status: Active Grant

• Current Assignee: Neurometrix, Inc.
• Original Assignee: Neurometrix, Inc.
• Inventors: Bansal, Pansy, Gozani, Shai N., Kong, Xuan
• Granted Patent: US 8,326,410 B2
• Time in Patent Office: Days
• US Class Current: 600/554
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/389 Electromyography [EMG]
• CPC Class Codes: A61B 5/4041 Evaluating nerves condition

Abstract

A novel submaximal F-wave acquisition and analysis system that employs computational intelligence to set up submaximal F-wave acquisition conditions and to extract submaximal F-wave features automatically, without operator intervention.

Claims

1. A method for acquiring and analyzing F-waves under a submaximal stimulation condition, the method comprising:

(i) applying a series of stimuli of variable intensity to a nerve;

(ii) recording a series of early responses;

(iii) determining a submaximal stimulation level for F-wave acquisition and analysis;

(iv) applying a series of stimuli of submaximal intensity to a nerve;

(v) recording a series of late responses;

(vi) regulating the submaximal stimulation and acquisition condition based on late response features;

(vii) analyzing late response to regulate the processing condition of F-wave features; and

(viii) characterizing F-wave features with trace-by-trace and/or total waveform set analysis.

2. A method according to claim 1 wherein the determination of the submaximal stimulation level is based on an early wave feature space.

3. A method according to claim 2 wherein the creation of the feature space is based on translating an early wave into a feature space.

4. A method according to claim 3, wherein the translation comprises the step of determining the local minima, local maxima, first deflection from baseline, and subsequent crossings of baseline level for the individual early responses.

5. A method according to claim 3, wherein the translation comprises the step of determining the local minima, local maxima, and zero crossings of the first and second order derivatives of the early responses.

6. A method according to claim 3, wherein the translation comprises the step of determining linear translation of the early responses.

7. A method according to claim 3, wherein the translation comprises the step of determining nonlinear translation of the early responses.

8. A method according to claim 2 wherein the determination of the submaximal stimulation level is based on one or more features as the result of one or more translation.

9. A method according to claim 8 wherein the determination further comprises the step of determining reference feature values in the feature space.

10. A method according to claim 8 wherein the determination further comprises the step of determining target feature values associated with the target submaximal stimulation intensity.

11. A method according to claim 8 wherein the determination further comprises the step of determining the target stimulation intensity based on the feature space characteristics.

12. A method according to claim 8 wherein the determination further comprises the step of determining of target stimulation intensity based on any known art of prediction, smoothing, interpolation, and estimation.

13. A method according to claim 1 wherein the late response feature comprises at least one selected from the group consisting of:

F-wave persistence, F-wave amplitude and its relationship with available dynamic range, F-wave morphology, A-wave presence, and artifacts commonly observed in late waves such as baseline fluctuation.

14. A method according to claim 1 wherein the step of regulating comprises the actions of changing at least one stimulation and acquisition condition selected from the group consisting of:

stimulation intensity, stimulation frequency, stimulation duration, late wave acquisition gain, digital waveform amplitude representation resolution such as analog-to-digital bits per sample, digital waveform time scale representation resolution such as sampling interval, analog and digital filter settings for conditioning late wave before display and feature analysis, and data acquisition window starting time and duration.

15. A method according to claim 1 wherein the step of regulating comprises the detection and localization of A-wave components.

16. A method according to claim 1 wherein the step of regulating comprises:

(a) masking A-wave segments of late responses from F-wave feature analysis;

(b) removing A-wave components from late responses prior to F-wave feature analysis; and

(c) altering F-wave feature analysis method settings to minimize the interference of A-wave components.

17. A method for diagnosing a disorder in a patient comprising:

(i) applying a series of stimuli of variable intensity to a nerve;

(ii) recording a series of early responses;

(iii) determining a submaximal stimulation level for F-wave acquisition and analysis;

(iv) applying a series of stimuli of submaximal intensity to a nerve;

(v) recording a series of late responses;

(vi) regulating the submaximal stimulation and acquisition condition based on late response features;

(vii) analyzing late responses to regulate the processing condition of F-wave features;

(viii) characterizing F-wave features with trace-by-trace and/or total waveform set analysis; and

(ix) comparing F-wave characteristics based on the submaximal late responses with those of normal character and those of known disorder.

18. A system for analyzing submaximal F-waves comprising:

(i) a stimulation electrode;

(ii) a stimulation circuit connected to the stimulation electrode for applying a series of stimuli to a nerve;

(iii) a detection electrode;

(iv) a detection circuit connected to the detection electrode; and

(v) an analyzer connected to the detection circuit and stimulation circuit and adapted to conduct submaximal F-wave analysis by;

(a) recording a series of early responses detected by the detection circuit and evoked by stimuli with variable intensities delivered by the stimulation circuit;

(b) determination of a submaximal stimulation level based on an early response feature space;

(c) recording a series of late responses detected by the detection circuit and evoked by submaximal stimulation;

(d) regulating the stimulation circuit by the analyzer based on late response features;

(e) recording and analyzing a series of late responses detected by the detection circuit; and

(f) altering the F-wave analysis setup and late response traces; and

(vi) apparatus for characterizing the F-wave features.

19. A method for submaximal F-wave acquisition and analysis, the method comprising:

(i) applying a series of stimuli of increasing intensity to a nerve;

(ii) recording a series of early responses;

(iii) determining the submaximal stimulation intensity based on a stimulus response curve and a target ratio between the submaximal and supramaximal early response magnitudes;

(iv) applying a series of stimuli of fixed intensity at the submaximal level to the nerve;

(v) recording a series of late responses;

(vi) detecting possible A-wave and H-reflex responses and excluding those segments from the late responses; and

(vii) extracting F-wave parameters from the remaining late wave segments.

20. A method for submaximal F-wave acquisition and analysis, the method comprising:

(i) applying a series of stimuli of increasing intensity to a nerve;

(ii) recording a series of early responses;

(iii) determining the submaximal stimulation intensity based on a percentage or magnitude reduction of the supramaximal stimulation intensity;

(iv) applying a series of stimuli of fixed intensity at the submaximal level to the nerve;

(v) recording a series of late responses;

(vi) detecting possible A-wave and H-reflex responses and excluding those waveform segments from the late responses; and

(vii) extracting F-wave parameters from the remaining late wave segments.

21. A method for submaximal F-wave acquisition and analysis, the method comprising:

(i) applying a series of stimuli of increasing intensity to a nerve;

(ii) recording a series of early responses;

(iii) determining the submaximal stimulation intensity based on a percentage or magnitude reduction of the supramaximal early response magnitude;

(iv) applying a series of stimuli of fixed intensity at the submaximal level to the nerve;

(v) recording a series of late responses;

(vi) detecting possible A-wave and H-reflex responses and excluding those waveform segments from the late responses;

(vii) applying a series of stimuli with an increased level of intensity capable of suppressing axon-reflex and/or H-reflex in the late responses;

(viii) recording a series of late responses; and

(ix) determining the F-wave characteristics based on the late responses.

22. A method for submaximal F-wave acquisition and analysis, the method comprising:

(i) applying a series of stimuli of increasing intensity to a nerve;

(ii) recording a series of early responses;

(iii) determining the submaximal stimulation intensity based on a stimulus response curve and a target ratio between the submaximal and supramaximal early response magnitudes;

(iv) applying a series of stimuli of fixed intensity at the submaximal level to the nerve;

(v) recording a series of late responses;

(vi) detecting possible A-wave and H-reflex responses and excluding those waveform segments from the late responses;

(vii) extracting F-wave features from the late responses;

(viii) applying a series of stimuli of fixed intensity at a higher level to the nerve;

(ix) recording a series of late responses;

(x) detecting possible A-wave and H-reflex responses and excluding those waveform segments from the late responses;

(xi) extracting F-wave features from the late responses; and

(xii) conducting a comparison analysis of F-wave features from lower and higher stimulation intensities.

23. A method for acquiring submaximal F-wave features, comprising:

(i) determining the stimulation intensity levels for submaximal F-wave acquisition;

(ii) acquiring and analyzing late waves under submaximal stimulation conditions;

(iii) modifying the stimulation conditions based on real-time monitoring of the late wave analysis outcomes; and

(iv) extracting and comparing F-wave features under alternative stimulation conditions.

24. Apparatus for acquiring submaximal F-wave features, comprising:

(i) a unit for determining the stimulation intensity levels for submaximal F-wave acquisition;

(ii) a unit for acquiring and analyzing late waves under submaximal stimulation conditions;

(iii) a unit for modifying the stimulation conditions based on real-time monitoring of the late wave analysis outcomes; and

(iv) a unit for extracting and comparing F-wave features under alternative stimulation conditions.