Apparatus and methods for assessment of neuromuscular function

• US 5,851,191 A
• Filed: 07/01/1997
• Issued: 12/22/1998
• Est. Priority Date: 07/01/1997
• Status: Expired due to Term

• Current Assignee: Neurometrix, Inc.
• Original Assignee: Neurometrix, Inc.
• Inventors: Gozani, Shai N.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US08/886,861
• Time in Patent Office: 539 Days
• Field of Search: 600/546, 600/548, 600/554
• US Class Current: 600/554
• CPC Class Codes: A61B 2505/05 Surgical care
• CPC Class Codes: A61B 5/05 Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves impedance plethysmography A61B5/0295; measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24
• CPC Class Codes: A61B 5/1106 to assess neuromuscular blockade, e.g. to estimate depth of anaesthesia
• 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 5/4041 Evaluating nerves condition
• CPC Class Codes: A61B 5/6824 Arm or wrist
• CPC Class Codes: A61B 5/6825 Hand
• CPC Class Codes: A61B 5/7217 of noise originating from a therapeutic or surgical apparatus, e.g. from a pacemaker
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives

Abstract

Apparatus and methods are provided for the assessment of neuromuscular function. Using an apparatus of the invention, stimuli are applied to a nerve that traverses the wrist of an individual. The stimuli are applied at a point that is proximal to the wrist. Stimulation of the nerve causes a muscle innervated by that nerve to respond. The muscle response generates a myoelectric potential, which is detected by an apparatus of the invention at a point that is proximal to the wrist. The delay between stimulation of a nerve and detection of a muscular response to that stimulation is processed to indicate an assessment of neuromuscular function. For example, a sufficient delay between application of stimulus and muscle response may indicate the presence of Carpal Tunnel Syndrome.

Claims

1. An apparatus for assessing a physiological function in an arm and a hand of an individual, comprising:

(a) a stimulator for producing a stimulus and for applying said stimulus proximal to a wrist of an individual, whereby application of said stimulus stimulates a nerve that traverses said wrist;

(b) a detector for detecting proximal to a wrist of an individual a myoelectric potential, whereby said myoelectric potential is generated by a muscle in a hand of said individual in response to said stimulus, said muscle being in communication with said nerve; and

(c) a controller for evaluating physiological function in response to said stimulus and said myoelectric potential.

2. The apparatus of claim 1, wherein said controller is further for determining a delay between application of said stimulus and detection of said myoelectric potential and for producing an indicia of said delay.

3. The apparatus of claim 2, further comprising a temperature sensor in electrical communication with said controller, said controller modifying said delay in response to said temperature.

4. The apparatus of claim 2, further comprising an indicator in electrical communication with said controller and for receiving said indicia from said controller and for indicating said delay in response to said indicia.

5. The apparatus of claim 4, wherein said indicator comprises a light emitting diode.

6. The apparatus of claim 2, wherein said controller is further for correlating said delay to said physiological function.

7. The apparatus of claim 6, wherein said controller is adapted for producing a signal indicative of the presence or absence of carpal tunnel syndrome in response to said physiological function.

8. The apparatus of claim 7, further comprising an indicator in electrical communication with said controller and for receiving said signal from said controller and for indicating the presence or absence of carpal tunnel syndrome in response to said signal.

9. The apparatus of claim 1, wherein said stimulator comprises a stimulation electrode for placement on said arm proximal to said wrist.

10. The apparatus of claim 1, wherein said detector comprises a detection electrode for placement on said arm proximal to said wrist.

11. The apparatus of claim 1, wherein said stimulus produced by said stimulator is an electrical stimulus.

12. The apparatus of claim 1, wherein said stimulus produced by said stimulator is a magnetic stimulus.

13. The apparatus of claim 1, further comprising a communications port for establishing communication between said controller and an external device, whereby said external device is adapted for evaluating and for indicating said physiological function in response to said stimulus and said myoelectric potential.

14. A method of assessing a physiological function in an arm and a hand of an individual, comprising the steps of:

(a) applying a stimulus proximal to a wrist of an individual whereby application of said stimulus stimulates a nerve that traverses said wrist;

(b) detecting a myoelectric potential proximal to a wrist of an individual, whereby said myoelectric potential is generated by a muscle in a hand of said individual in response to said stimulus, said muscle being in communication with said nerve;

(c) processing said stimulus and said myoelectric potential; and

(d) correlating said processing results to a physiological function of said nerve and said muscle.

15. The method of claim 14, wherein said processing step further comprises the step of determining a delay between application of said stimulus and detection of said myoelectric potential and said correlating step further comprises the step of producing an indicia of said delay.

16. The method of claim 15, further comprising the step of indicating said delay in response to said indicia.

17. The method of claim 15, wherein said correlating step further comprises the step of correlating said delay to said physiological function.

18. The method of claim 17, further comprising the step of producing a signal indicative of the presence or absence of carpal tunnel syndrome in response to said physiological function.

19. The method of claim 18, further comprising the step of indicating the presence or absence of carpal tunnel syndrome in response to said signal.

20. The method of claim 16, wherein said step of determining a delay between application of said stimulus and detection of said myoelectric potential comprises the step of determining a second derivative of said myoelectric potential.

21. The method of claim 15, wherein said step of determining a delay between application of said stimulus and detection of said myoelectric potential comprises the step of determining a first derivative of said myoelectric potential.

22. The method of claim 14, further comprising the steps of determining a first derivative of said myoelectric potential and repeating steps (a) and (b) at incrementally increasing stimuli magnitudes until said first derivative for one of said myoelectric potentials exceeds a predetermined level.

23. The method of claim 14, further comprising the steps of determining a delay between application of said stimulus and detection of said myoelectric potential for at least two stimulus applications, comparing the delays determined in response to application of each of said at least two stimulus applications and correlating said comparison to the presence or absence of carpal tunnel syndrome.