Evoked EMG signal processing

• US 4,964,411 A
• Filed: 07/13/1989
• Issued: 10/23/1990
• Est. Priority Date: 07/13/1989
• Status: Expired due to Term

• Current Assignee: Encore Medical Asset Corporation (Enovis Corp.)
• Original Assignee: EMPI Incorporated (Enovis Corp.)
• Inventors: Johnson, Michael T., Kipnis, Alexander
• Primary Examiner(s): Cohen, Lee S.
• Assistant Examiner(s): Pontius, Kevin
• Application Number:
  US07/379,415
• Time in Patent Office: 467 Days
• Field of Search: 128/733, 128/905, 623/25, 364/413.02, 364/413.05, 364/413.27
• US Class Current: 600/546
• CPC Class Codes: A61B 5/389 Electromyography [EMG]
• CPC Class Codes: A61B 5/395 Details of stimulation, e.g. nerve stimulation to elicit EMG response
• CPC Class Codes: A61B 5/407 Evaluating the spinal cord A61B5/4896 takes precedence
• CPC Class Codes: A61N 1/36014 External stimulators, e.g. with patch electrodes external pacemakers A61N1/3625
• CPC Class Codes: A61N 1/36017 with leads or electrodes penetrating the skin

Abstract

A method generates signal data which is representative of short and long latency components of myoelectric signals. Production of myoelectric signals is repeatedly evoked in a muscle with triggering events. Myoelectric signal data which is representative of the produced myoelectric signals is stored as a temporal function of the triggering events. The myoelectric signal data is averaged before it is demodulated to produce short latency signal data representative of the short latency components of the myoelectric signals. The myoelectric signal data is also demodulated before it is averaged to produce combined short and long latency signal data. The combined signal data is summed with the short latency signal data to isolate the long latency signal data.

Claims

1. A method of separating dispersive and synchronous time varying myoelectric signals, comprising:

repeatedly evoking the production of myoelectric signals in a muscle with triggering events;

storing myoelectric signal data representative of the produced myoelectric signals as temporal functions of the triggering events;

averaging the myoelectric signal data before any demodulation of the data to produce short latency signal data representative of the short latency components of the myoelectric signals;

demodulating the short latency signal data to obtain demodulated short latency signal data;

demodulating the myoelectric signal data before averaging;

averaging the demodulated myoelectric signal data to obtain combined data representative of short and long latency myoelectric signals; and

combining the combined data with the demodulated short latency signal data to isolate long latency signal data representative of long latency components of the myoelectric signals.

2. The method of claim 1 wherein the step of demodulating the short latency signal data further comprises:

rectifying the short latency signal data; and

filtering the short latency signal data.

3. The method of claim 1 wherein the step of demodulating the myoelectric signal data further comprises:

rectifying the signal data; and

filtering the signal data.

4. The method of claim 1 wherein the step of repeatedly evoking production of myoelectric signals further comprises:

activating a muscle spindle receptor mediated stretch reflex.

5. The method of claim 4 wherein the step of activating further comprises:

stretching the muscle.

6. The method of claim 1 wherein the step of repeatedly evoking production of myoelectric signals further comprises:

artificially activating fibers from muscle spindle receptors.

7. The method of claim 6 wherein the step of artificially activating fibers further comprises:

electrically stimulating a mixed motor-sensory nerve.

8. The method of claim 1 wherein the step of storing myoelectric signal data further comprises:

storing activation data representative of activation of muscle fibers in the muscle caused by signals provided to the muscle by alpha motorneurons in response to the triggering event.

9. A method for generating signal data representative of short latency, long latency and combined short and long latency signal components of myoelectric signals, comprising:

repeatedly evoking the production of myoelectric signals in a muscle with triggering events;

storing myoelectric signal data representative of the myoelectric signals produced in the muscle as temporal functions of the triggering events;

averaging the myoelectric signal data, before demodulating the myoelectric signal data, to produce short latency signal data representative of the short latency signal components of the myoelectric signals;

demodulating the myoelectric signal data, before averaging the myoelectric signal data, to produce demodulated signal data;

averaging the demodulated signal data to produce combined signal data representative of the short and long latency signal components of the myoelectric signals; and

combining the short latency signal data with the combined signal data to produce long latency signal data representative of the long latency signal components of the myoelectric signals.

10. The method of claim 9 and further comprising:

demodulating the short latency signal data, before the step of combining, to produce demodulated short latency signal data.

11. The method of claim 10 wherein the step of demodulating further comprises:

rectifying the short latency signal data; and

filtering the short latency signal data.

12. The method of claim 9 wherein the step of demodulating further comprises:

rectifying the myoelectric signal data; and

filtering the myoelectric signal data.

13. A method for separating signal data representing short latency signal components of myoelectric signals from signal data representing long latency and short latency signal components of the myoelectric signals, comprising:

triggering the production of myoelectric signals in a muscle a plurality of times with triggering events;

storing myoelectric signal data, representative of the myoelectric signals, as temporal functions of the triggering events;

averaging the myoelectric signal data before demodulating the data to produce short latency signal data representative of the short latency signal components of the myoelectric signals;

demodulating the short latency signal data;

demodulating the myoelectric signal data stored to produce demodulated myoelectric signal data;

averaging the demodulated myoelectric signal data to obtain combined signal data representative of short and long latency myoelectric signals; and

combining the short latency signal data with the combined signal data to obtain dispersive signal data representative of the long latency myoelectric signals.

14. The method of claim 13 wherein the step of demodulating the short latency signal data further comprises:

rectifying the short latency signal data; and

filtering the short latency signal data.

15. The method of claim 13 wherein the step of demodulating the myoelectric signal data further comprises:

rectifying the myoelectric signal data; and

filtering the myoelectric signal data.

16. A method of separating a plurality of signal components of myoelectric signals comprising:

triggering, with a triggering event, myoelectric signals in a muscle;

storing signal data representative of the myoelectric signals as a temporal function of the triggering event;

repeating the steps of triggering and storing a plurality of times;

averaging the signal data stored, before demodulating, to increase signal to noise ratio and to substantially eliminate components of the signal data representative of cortically generated myoelectric signals;

demodulating the signal data which was averaged;

demodulating the signal data stored, before averaging to produce demodulated signal data;

averaging the demodulated signal data to obtain combined signal data representative of short and long latency myoelectric signals; and

combining the short latency signal data with the combined signal data to produce dispersive data representative of long latency myoelectric signals.

17. The method of claim 16 wherein the step of demodulating the signal data which was averaged further comprises:

rectifying the signal data which was averaged; and

filtering the signal data which was rectified.

18. The method of claim 16 wherein the step of demodulating the signal data stored further comprises:

rectifying the signal data; and

filtering the signal data.

19. A method of separating supraspinal originated electromyographic (EMG) signals from spinal originated EMG signals comprising:

applying a triggering input to a muscle to induce EMG signals in the muscle;

synchronizing detection of the EMG signals with the triggering input;

storing data representative of the signals being detected as a time function of the triggering input;

repeating the steps of applying, synchronizing and storing a plurality of times;

averaging the data representative of the EMG signals which was stored, before demodulating, to produce an averaged signal representation representative of the spinal originated EMG signals;

demodulating the averaged signal representation to obtain a demodulated averaged signal representation;

demodulating the data stored to obtain demodulated data;

averaging the demodulated data to obtain combined signal data representative of spinal and supraspinal originated EMG signals; and

combining the demodulated averaged signal representation with the combined signal data to produce dispersive data representative of the supraspinal originated EMG signals.

20. The method of claim 19 wherein the step of demodulating the averaged signal representation further comprises:

rectifying the averaged signal representation; and

filtering the averaged signal representation to produce an averaged, rectified signal representation.

21. The method of claim 19 wherein the step of demodulating the data stored further comprises:

rectifying the data stored; and

filtering the data stored.