Method and apparatus for detecting epileptic seizures

• US 5,349,962 A
• Filed: 11/30/1993
• Issued: 09/27/1994
• Est. Priority Date: 11/30/1993
• Status: Expired due to Term

• Current Assignee: University of Washington
• Original Assignee: University of Washington
• Inventors: Lockard, Joan S., Congdon, William C. Jr., Kalk, Douglas F., DuCharme, Larry L.
• Primary Examiner(s): Sykes, Angela D.
• Application Number:
  US08/159,855
• Time in Patent Office: 301 Days
• Field of Search: 128/731.3
• US Class Current: 600/545
• CPC Class Codes: A61B 5/374 Detecting the frequency distribution of signals, e.g. detecting delta, theta, alpha, beta or gamma waves
• CPC Class Codes: A61B 5/4094 Diagnosing or monitoring seizure diseases, e.g. epilepsy

Abstract

A method and apparatus for accurately determining the onset or occurrence of an epileptic seizure is disclosed. The system includes an electroencephalograph (EEG) and an electromyograph (EMG) which provide signals to a signal processor. The signal processor operates to generate a digitized envelope waveform of the EEG waveform and the EMG waveform. If the waveforms all have an amplitude within a predetermined threshold, for a predetermined time interval, a CPU provides a signal to an output display indicative of a epileptic seizure.

Claims

1. A method of detecting an epileptic seizure in a person comprising the steps of:

(a) monitoring the amount of brain activity of said person to produce a brain activity signal and monitoring the amount of motor activity of said person to produce a motor activity signal;

(b) sampling said brain activity signal at a sampling frequency to produce a brain activity signal amplitude and sampling said motor activity signal at said sampling frequency to produce a motor activity signal amplitude;

(c) incrementing a brain activity counter when said brain activity signal amplitude is within a predetermined brain window and decrementing said brain activity counter when said brain activity signal is without said predetermined brain window;

(d) incrementing a motor activity counter when said motor activity signal amplitude is within a predetermined motor window and decrementing said motor activity counter when said motor activity signal is without said predetermined motor window; and

(e) indicating that an epileptic seizure is occurring when said brain activity counter is above a brain threshold and said motor activity counter is above a motor threshold.

2. The method of claim 1 further including the steps of:

determining the maximum amplitude of said brain activity signal when said brain activity counter is above said brain threshold; and

determining the maximum amplitude of said motor activity signal when said motor activity counter is above said motor threshold.

3. The method of claim 1 further including the steps of:

determining the average amplitude of said brain activity signal over the interval when said brain activity counter is above said brain threshold; and

determining the average amplitude of said motor activity signal over the interval when said motor activity counter is above said motor threshold.

4. The method of claim 1 further including the step of determining the duration of time in which said brain activity counter is above said brain threshold and the said motor activity counter is above said motor threshold.

5. The method of claim 1 wherein the step of monitoring the brain activity of said person is done by means of an electroencephalograph (EEG) and said brain activity signal is an EEG waveform and wherein the step of monitoring the motor activity of said person is done by means of an electromyograph (EMG) and said motor activity signal is an EMG waveform.

6. The method of claim 5 wherein said EEG waveform has a positive EEG component and a negative EEG component and wherein said EMG waveform has a positive EMG component and a negative EMG component, wherein said step of sampling is acted upon said positive EEG component, said negative EEG component, said positive EMG component, and said negative EMG component, further wherein said brain activity counter includes a positive brain activity counter and a negative brain activity counter and wherein said motor activity counter includes a positive motor activity counter and a negative motor activity counter, the method further including the steps of:

(a) integrating said positive EEG component to provide a positive EEG envelope waveform and integrating said negative EEG component to provide a negative EEG envelope waveform;

(b) integrating said positive EMG component to provide a positive EMG envelope waveform and integrating said negative EMG component to provide a negative EMG envelope waveform;

(c) incrementing said positive brain activity counter when said positive EEG envelope waveform is within said predetermined brain window and decrementing said positive brain activity counter when said positive EEG envelope waveform is without said predetermined brain window;

(d) incrementing said negative brain activity counter when said negative EEG envelope waveform is within said predetermined brain window and decrementing said negative brain activity counter when said negative EEG envelope waveform is without said predetermined brain window;

(e) incrementing said positive motor activity counter when said positive EMG envelope waveform is within said predetermined motor window and decrementing said positive motor activity counter when said positive EMG envelope waveform is without said predetermined motor window, and

(f) incrementing said negative motor activity counter when said negative EMG envelope waveform is within said predetermined motor window and decrementing said negative motor activity counter when said negative EMG envelope waveform is without said predetermined motor window.

7. A method of detecting an epileptic seizure in a person comprising the steps of:

(a) monitoring the amount of brain activity of said person as to produce a brain activity signal and monitoring the amount of motor activity of said person to produce a motor activity signal;

(b) determining if the amplitude of said brain activity signal falls within a predetermined brain window for a predetermined brain window period and determining if the amplitude of said motor activity signal falls within a predetermined motor window for a predetermined motor window period; and

(c) indicating that an epileptic seizure has occurred when said amplitude of said brain activity signal falls within a predetermined brain window for a predetermined brain window period and the amplitude of said motor activity signal falls within a predetermined motor window for a predetermined motor window period.

8. The method of claim 7 further including the steps of:

determining the maximum amplitude of said brain activity signal over the interval said brain activity signal falls within said predetermined brain window; and

determining the maximum amplitude of said motor activity signal over the interval said motor activity signal falls within said predetermined motor window.

9. The method of claim 7 further including the steps of:

determining the average amplitude of said brain activity signal over the interval when said brain activity signal falls within said predetermined brain window; and

determining the average amplitude of said motor activity signal over the interval when said motor activity signal falls within said predetermined motor window.

10. The method of claim 7 further including the step of:

determining the duration of time in which the amplitude of said brain activity signal falls within said predetermined brain window and the amplitude of said motor activity signal falls within said predetermined motor window.

11. The method of claim 7 including wherein the step of monitoring the brain activity of said person is done by means of an electroencephalograph (EEG) and said brain activity signal is an EEG waveform and wherein the step of monitoring the motor activity of said person is done by means of an electromyograph (EMG) and said motor activity signal is an EMG waveform.

12. The method of claim 11 further wherein said EEG waveform has a positive EEG component and a negative EEG component and wherein said EMG waveform has a positive EMG component and a negative EMG component, the method further including the steps of:

(a) integrating said positive EEG component to provide a positive EEG envelope waveform and integrating said negative EEG component to provide a negative EEG envelope waveform;

(b) integrating said positive EMG component to provide a positive EMG envelope waveform and integrating said negative EMG component to provide a negative EMG envelope waveform;

(c) determining whether the amplitude of said positive EEG envelope waveform falls within said predetermined window for said predetermined brain window period and determining whether the amplitude of said negative EEG envelope waveform falls within said predetermined window for said predetermined brain window period;

(d) determining whether the amplitude of said positive EMG envelope waveform falls within said predetermined window for said predetermined motor window period and determining whether the amplitude of said negative EMG envelope waveform falls within said predetermined window for said predetermined motor window period; and

(e) indicating that an epileptic seizure has occurred when said amplitude of said positive EEG envelope waveform falls within said predetermined brain window for said predetermined brain window period, when the amplitude of said negative EEG envelope waveform falls within said predetermined brain window for said predetermined brain window period, when the amplitude of said positive EMG envelope waveform falls within said predetermined motor window for said predetermined motor window period, and when the amplitude of said negative EMG envelope waveform falls within said predetermined motor window for said predetermined motor window period.

13. A method of detecting an epileptic seizure in a person comprising the steps of:

(a) monitoring the amount of brain activity of said person to produce a brain activity signal;

(b) sampling said brain activity signal at a sampling frequency to produce a brain activity signal amplitude;

(c) incrementing a brain activity counter when said brain activity signal amplitude is within a predetermined brain window and decrementing said brain activity counter when said brain activity signal is without said predetermined brain window; and

(e) indicating that an epileptic seizure is occurring when said brain activity counter is above a brain threshold.

14. The method of claim 13 wherein the step of monitoring the brain activity of said person is done by means of an electroencephalograph (EEG) and said brain activity signal is an EEG waveform.

15. The method of claim 14 wherein said EEG waveform has a positive EEG component and a negative EEG component, wherein said step of sampling is acted upon said positive EEG component and said negative EEG component, further wherein said brain activity counter includes a positive brain activity counter and a negative brain activity counter, the method further including the step of:

(a) integrating said positive EEG component to provide a positive EEG envelope waveform and integrating said negative EEG component to provide a negative EEG envelope waveform;

(b) incrementing said positive brain activity counter when said positive EEG envelope waveform is within said predetermined brain window and decrementing said positive brain activity counter when said positive EEG envelope waveform is without said predetermined brain window, and

(c) incrementing said negative brain activity counter when said negative EEG envelope waveform is within said predetermined brain window and decrementing said negative brain activity counter when said negative EEG envelope waveform is without said predetermined brain window.

16. A method of detecting an epileptic seizure in a person comprising the steps of:

(a) monitoring the amount of motor activity of said person as a motor activity signal;

(b) sampling said motor activity signal at a sampling frequency to produce a motor activity signal amplitude;

(c) incrementing a motor activity counter when said motor activity signal amplitude is within a predetermined motor window and decrementing said motor activity counter when said motor activity signal is without said predetermined motor window; and

(e) indicating that an epileptic seizure is occurring when said motor activity counter is above a motor threshold.

17. The method of claim 16 wherein the step of monitoring the brain activity of said person is done by means of an electromyograph (EMG) and said motor activity signal is an EMG waveform.

18. The method of claim 17 wherein said EMG waveform has a positive EMG component and a negative EMG component, wherein said step of sampling is acted upon said positive EMG component and said negative EMG component, further wherein said motor activity counter includes a positive motor activity counter and a negative motor activity counter, the method further including the step of:

(a) integrating said positive EMG component to provide a positive EMG envelope waveform and integrating said negative EMG component to provide a negative EMG envelope waveform;

(b) incrementing said positive motor activity counter when said positive EMG envelope waveform is within said predetermined motor window and decrementing said positive motor activity counter when said positive EMG envelope waveform is without said predetermined motor window; and

(c) incrementing said negative motor activity counter when said negative EMG envelope waveform is within said predetermined motor window and decrementing said negative motor activity counter when said negative EMG envelope waveform is without said predetermined motor window.

19. A method of detecting an epileptic seizure in a person comprising the steps of:

(a) monitoring the amount of brain activity of said person as a brain activity signal;

(b) determining if the amplitude of said brain activity signal falls within a predetermined brain window for a predetermined brain window period; and

(c) indicating that an epileptic seizure has occurred when said amplitude of said brain activity falls within a predetermined brain window for a predetermined brain window period.

20. The method of claim 19 including wherein the step of monitoring the brain activity of said person is done by means of an electroencephalograph (EEG) and said brain activity signal is an EEG waveform.

21. The method of claim 20 further wherein said EEG waveform has a positive EEG component and a negative EEG component, the method further including the steps of:

(a) integrating said positive EEG component to provide a positive EEG envelope waveform and integrating said negative EEG component to provide a negative EEG envelope waveform;

(b) determining whether the amplitude of said positive EEG envelope waveform falls within said predetermined window for said predetermined brain window period and determining whether the amplitude of said negative EEG envelope waveform falls within said predetermined brain window for said predetermined brain window period; and

(c) indicating that an epileptic seizure has occurred when said amplitude of said positive EEG envelope waveform falls within said predetermined window for said predetermined brain window period and when the amplitude of said negative EEG envelope waveform falls within said predetermined brain window for said predetermined brain window period.

22. A method of detecting an epileptic seizure in a person comprising the steps of:

(a) monitoring the amount of motor activity of said person as a motor activity signal;

(b) determining if the amplitude of said motor activity signal falls within a predetermined motor window for a predetermined motor window period; and

(c) indicating that an epileptic seizure has occurred when said amplitude of said motor activity signal falls within a predetermined motor window for a predetermined motor window period.

23. The method of claim 22 including wherein the step of monitoring the brain activity of said person is done by means of an electromyograph (EMG) and said motor activity signal is an EMG waveform.

24. The method of claim 23 further wherein said EMG waveform has a positive EMG component and a negative EMG component, the method further including the steps of:

integrating said positive EMG component to provide a positive EMG envelope waveform and integrating said negative EMG component to provide a negative EMG envelope waveform;

determining whether the amplitude of said positive EMG envelope waveform falls within said predetermined window for said predetermined motor window time and determining whether the amplitude of said negative EMG envelope waveform falls within said predetermined window for said predetermined motor window period; and

indicating that an epileptic seizure has occurred when said amplitude of said positive EMG envelope waveform falls within said predetermined motor window for said predetermined motor window time and when the amplitude of said negative EMG envelope waveform falls within said predetermined motor window for said predetermined motor window period.

25. An apparatus for detecting an epileptic seizure in a person comprising:

(a) a brain monitor monitoring the amount of brain activity of said person and producing a brain activity signal;

(b) a motor monitor monitoring the amount of motor activity of said person and producing a motor activity signal;

(c) CPU means for receiving said brain activity signal from said brain monitor and sampling said brain activity signal at a sampling frequency to produce a brain activity signal amplitude and said CPU means for receiving said motor activity signal from said motor monitor and sampling said motor activity signal at said sampling frequency to produce an motor activity signal amplitude, said CPU means also operative to increment a brain activity counter when said brain activity signal amplitude is within said predetermined brain window and decrementing said brain activity counter when said brain activity signal is without said predetermined brain window, said CPU means also operative to increment a motor activity counter when said motor activity signal amplitude is within said predetermined motor window and decrementing said motor activity counter when said motor activity signal is without said predetermined motor window; and

(d) output display means, said output display means connected to said CPU means for indicating that an epileptic seizure is occurring when said brain activity counter is above a brain threshold and said motor activity counter is above a motor threshold.

26. The apparatus of claim 25 further including:

means for determining the maximum amplitude of said brain activity signal when said brain activity counter is above said brain threshold; and

means for determining the maximum amplitude of said motor activity signal when said motor activity counter is above said motor threshold.

27. The method of claim 25 further including:

means for determining the average amplitude of said brain activity signal over the interval when said brain activity counter is above said brain threshold; and

means for determining the average amplitude of said motor activity signal over the interval when said motor activity counter is above said motor threshold.

28. The method of claim 25 further including means for determining the duration of time in which said brain activity counter is above said brain threshold and the said motor activity counter is above said motor threshold.

29. The method of claim 25 wherein said brain monitor is an electroencephalograph (EEG) and said brain activity signal is an EEG waveform and said motor monitor is an electromyograph (EMG) and said motor activity signal is an EMG waveform.

30. The apparatus of claim 29 wherein said EEG waveform has a positive EEG component and a negative EEG component and wherein said EMG waveform has a positive EMG component and a negative EMG component, the apparatus further comprising:

(a) means for integrating said positive EEG component to provide a positive EEG envelope waveform and integrating said negative EEG component to provide a negative EEG envelope waveform;

(b) means for integrating said positive EMG component to provide a positive EMG envelope waveform and integrating said negative EMG component to provide a negative EMG envelope waveform;

wherein said CPU means samples said positive EEG envelope waveform, said negative EEG envelope waveform, said positive EMG envelope waveform, and said negative EMG envelope waveform,

further wherein said brain activity counter includes a positive brain activity counter and a negative brain activity counter, said positive brain activity counter being incremented when said positive EEG envelope waveform is within said predetermined brain window and decremented when said positive EEG envelope waveform is without said predetermined brain window, said negative brain activity counter being incremented when said negative EEG envelope waveform is within said predetermined brain window and decremented when said negative EEG envelope waveform is without said predetermined brain window; and

further wherein said motor activity counter includes a positive motor activity counter and a negative motor activity counter, said positive motor activity counter being incremented when said positive EMG envelope waveform is within said predetermined motor window and decremented when said positive EMG envelope waveform is without said predetermined motor window, said negative motor activity counter being incremented when said negative EMG envelope waveform is within said predetermined motor window and decremented when said negative EMG envelope waveform is without said predetermined motor window.