Electromyographic treatment device

• US 5,300,096 A
• Filed: 06/03/1992
• Issued: 04/05/1994
• Est. Priority Date: 06/03/1992
• Status: Expired due to Fees

• Current Assignee: Electronic Medical Instruments, Inc.
• Original Assignee: Electronic Medical Instruments, Inc.
• Inventors: Fields, R. Wayne, Tillman, James E., Hall, H. Eugene, Munday, William A.
• Primary Examiner(s): Cohen, Lee S.
• Assistant Examiner(s): JASTRZAB, JEFFREY R
• Application Number:
  US07/892,942
• Time in Patent Office: 671 Days
• Field of Search: 128/421, 128/419 R, 128/422, 128/423 R, 128/423 W, 128/733, 128/901, 128/905
• US Class Current: 607/48
• CPC Class Codes: A61N 1/36003 of motor muscles, e.g. for walking assistance

Abstract

An electrical muscle stimulator converts electromyographic (EMG) signals to digital words for analysis and display by a computer program. The therapist selects a variety of different parameters appropriate for the individual patient, and instructs the device to initiate stimulating signals on command, or upon detection of a suitable EMG signal from the patient. The device that converts digital words representing the selected parameters into complex, bipolar therapeutic pulses. The device can digitally model a wide variety of wave forms and graphically assist the therapist in developing and shaping various wave pulse trains.

Claims

1. An electromyographic treatment system having a treatment device and including and operated by a computer having an interactive graphic display, the treatment device comprising:

a reference electrode and a pair of active electrodes for sensing electromyographic signals from a patient and for delivering an electrical stimulation signal to the patient;

an electromyographic sensing circuit connected to the electrodes, having input signal conditioning means for converting the sensed signals to digital electromyographic words representative of the sensed signals and having an automatic nulling means for establishing a null signal level representative of a background electromyographic signal generated by the patient at rest;

an electrical stimulation circuit connected to the active electrodes, having output signal conditioning means for converting a series of digital stimulation words into a plurality of complex, bipolar voltage pulses forming a series of preselected therapeutic pulse trains defining a stimulation signal;

electronic interconnecting means for interconnecting the sensing and stimulation circuits and for interconnecting the sensing and stimulation circuits with the computer; and

software means for use in conjunction with the personal computer for accepting the electromyographic words and generating a normalized image of the sensed signals for display on the interactive graphical display, enabling a therapist to view the sensed signals, enter a plurality of therapeutic parameters into the display, view a graphic representation of a resulting therapeutic pulse train, and for sending digital stimulation words representative of the therapeutic parameters to the stimulation circuit.

2. The treatment device of claim 1, wherein the software means includes selected display parameters for:

pulse train repetitions, rise time, amplitude, fall time and duration;

pulse cycle frequency and shape;

electromyographic threshold for stimulation; and

, wherein the software means also stores the selected display parameters for different patients and generates a normalized real time graph of the stimulation signal.

3. The treatment device of claim 1, including a plurality of reference electrodes and active electrode pairs connected to additional sensing and stimulation means connected to the interconnecting means, wherein the software means display parameters include delay times for each active electrode pair.

4. The treatment device of claim 1, wherein the stimulation circuit has two addressable digital to analog converters for generating addressed unipolar pulses from the digital stimulation words and wherein the device further includes a center tapped voltage transformer having opposite sides of a primary winding connected to the two addressable digital to analog converters so that the addressed unipolar pulses are directed to opposite sides of the center taped voltage transformer to produce the bipolar voltage pulses.

5. The treatment device of claim 1, wherein the sensing circuit includes in series a precision amplifier, a 60 Hz filter, a full wave rectifier generating negative pulses, a peak detector, an automatic offset nulling circuit having an output, a scale amplifier having digitally selectable gain, and an analog to digital converter.

6. The treatment device of claim 5, including clamp circuit means connected to the output of the offset nulling circuit for preventing the output from falling below a ground voltage thereby preventing overnulling.

7. The treatment device of claim 5, wherein the full wave rectifier includes a voltage follower having an output and having inverting and non-inverting inputs with a first forward biased diode connected between the output and the inverting input of the follower as part of a negative feedback loop and to an inverting input of an operational amplifier configured with first and second resistors as an inverting amplifier having a voltage gain of -1, the follower output also being connected by a second reverse bias diode to a grounded third resistor and through a fourth resistor to a non-inverting input of the operational amplifier now configured as a non-inverting amplifier with a voltage gain of +1 due to the opposite biasing of the first and second diodes.

8. An electromyographic treatment system having a treatment device and including and operated by a computer having an interactive graphic display, the treatment device comprising:

a reference electrode and a pair of active electrodes for sensing electromyographic signals from a patient and for delivering an electrical stimulation signal to the patient;

an electromyographic sensing circuit connected to the electrodes, having input signal conditioning means for converting the sensed signals to digital electromyographic words representative of the sensed signals;

an electrical stimulation circuit connected to the active electrodes, having output signal means for converting a series of digital stimulation words into a plurality of complex, bipolar pulses forming a series of preselected therapeutic pulse trains defining a stimulation signal;

electronic interconnecting means for interconnecting the sensing and stimulation circuits and for interconnecting the sensing and stimulation circuits with the computer; and

software means for use in conjunction with the personal computer for accepting the electromyographic words and generating a normalized image of the sensed signals for display on the interactive graphical display, enabling a therapist to view the sensed signals, enter a plurality of therapeutic parameters into the display, view a graphic representation of a resulting therapeutic pulse train, and for sending digital stimulation words representative of the therapeutic parameters to the stimulation circuit.

9. The treatment device of claim 8, wherein the software means includes selected display parameters for:

pulse train repetitions, rise time, amplitude, fall time and duration;

pulse cycle frequency and shape;

electromyographic threshold for stimulation; and

, wherein the software means also stores the selected display parameters for different patients and generates a normalized real time graph of the stimulation signal.

10. The treatment device of claim 8, including a plurality of reference electrodes and active electrode pairs connected to additional sensing and stimulation circuits connected to the interconnecting device, wherein the software means display parameters include delay times for each active electrode pair.

11. The treatment device of claim 8, wherein the stimulation circuit has two addressable digital to analog converters for generating addressed unipolar pulses from the digital stimulation words and wherein the device further includes a center tapped voltage transformer having opposite sides of a primary winding connected to the two addressable digital to analog converters so that addressed unipolar pulses are directed to opposite sides of the center taped voltage transformer to produce the bipolar voltage pulses.

12. The treatment device of claim 8, wherein the sensing circuit includes in series an instrumentation amplifier, a 60 Hz filter, a full wave rectifier generating negative pulses, a peak detector, an automatic nulling device establishing a null signal level representative of a background electromyographic signal generated by the patient at rest, a scale amplifier having digitally selectable gain, and an analog to digital converter.

13. The treatment device of claim 8, including a clamp circuit and an automatic nulling device having an output, wherein the automatic nulling device output is connected to the clamp circuit so as to prevent the output from falling below a ground voltage thereby preventing overnulling which can be uncomfortable to the patient.

14. The treatment device of claim 13, wherein the full wave rectifier includes a voltage follower having an output and having inverting and non-inverting inputs with a first forward biased diode connected between the output and the inverting input of the follower as part of a negative feedback loop and to an inverting input of an operational amplifier configured with first and second resistors as an inverting amplifier having a voltage gain of -1, the follower output also being connected by a second reverse bias diode to a grounded third resistor and through a fourth resistor to a non-inverting input of the operational amplifier now configured as a non-inverting amplifier with a voltage gain of +1 due to the opposite biasing of the first and second diodes.

15. A method for generating complex bipolar pulses forming a series of preselected therapeutic pulse trains defining a stimulation signal, comprising the steps of:

viewing an electromyographic background signal from a patient at rest on a screen in a time domain;

enabling a digital counter which drives a digital to analog converter until the background signal is nulled out;

asking the patient to initiate a contraction of a muscle of interest so as to generate an electromyographic signal;

viewing a representation of the electromyographic signal and entering a threshold electromyographic level into a graphic interface in response thereto;

entering a plurality of therapeutic parameters into the graphic interface, the parameters being represented as digital words in a computer program; and

converting the digital words into stimulation signals and applying the stimulation signals to a patient.

16. The method of claim 15, wherein during the threshold entering step both upper and relaxed threshold electromyographic levels are entered into the graphic interface.