METHOD AND SYSTEM FOR DETERMINING AN OPERABLE STIMULUS INTENSITY FOR NERVE CONDUCTION TESTING

• US 20070185409A1
• Filed: 02/15/2007
• Published: 08/09/2007
• Est. Priority Date: 04/20/2005
• Status: Abandoned Application

• Current Assignee: Natus Medical Incorporated
• Original Assignee: Natus Medical Incorporated
• Inventors: WU, Jianping, KURTZ, Ronald
• Application Number:
  US11/675,351
• Publication Number:
  US 20070185409A1
• 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 5/388 Nerve conduction study, e.g. detecting action potential of peripheral nerves
• CPC Class Codes: A61B 5/4041 Evaluating nerves condition

Abstract

The described embodiments relate generally to methods, systems and apparatus for automatic nerve stimulation and for determining an operable stimulus intensity for nerve conduction testing. The method of determining an operable stimulus intensity for nerve conduction testing comprises: repeatedly stimulating a body portion adjacent a nerve at an increasing stimulus intensity; detecting a response potential in response to each stimulation of the body portion; determining a plurality of averaged responses based on the detected response potentials, each averaged response being an average of a set of at least two consecutive response potentials, each set of response potentials having at least one response potential not in another set; determining at least two parameters of each averaged response; determining that a maximal stimulus intensity has been reached when the respective at least two parameters of at least two averaged responses are within a predetermined percentage range; and determining the operable stimulus intensity as a predetermined proportion of the maximal stimulus intensity.

Claims

1. A method of determining an operable stimulus intensity for nerve conduction testing, comprising:

repeatedly stimulating a body portion adjacent a nerve at an increasing stimulus intensity;

detecting a response potential in response to each stimulation of the body portion;

determining a plurality of averaged responses based on the detected response potentials, each averaged response being an average of a set of at least two consecutive response potentials, each set of response potentials having at least one response potential not in another set;

determining at least two parameters of each averaged response;

determining that a maximal stimulus intensity has been reached when the respective at least two parameters of at least two averaged responses are within a predetermined range; and

determining the operable stimulus intensity as a predetermined proportion of the maximal stimulus intensity.

2. The method of claim 1, wherein the predetermined proportion is about 110%.

3. The method of claim 1, wherein the predetermined range is a percentage range of 0 to 20%.

4. The method of claim 1, wherein the at least two averaged responses comprise three averaged responses.

5. The method of claim 1, wherein the at least two averaged responses are consecutive averaged responses.

6. The method of claim 1, wherein the at least two parameters are selected from the group consisting of:

onset time, peak amplitude and the area of the response potential between peak amplitude and onset.

7. The method of claim 1, wherein each averaged response comprises an average of three consecutive response potentials.

8. The method of claim 1, wherein the steps of stimulating and detecting comprise:

a) determining a stimulus intensity at which to provide a stimulus to the body portion;

b) stimulating the body portion with the stimulus at the stimulus intensity; and

c) detecting the response potential of the body portion in response to the stimulus.

9. The method of claim 8, wherein the steps of stimulating and detecting further comprise:

d) reducing the stimulus intensity by a first predetermined amount and once repeating steps b) and c);

e) verifying that the reduced stimulus intensity corresponds to detecting a reduced response potential in response to the reduced stimulus intensity;

f) increasing the stimulus intensity by a second predetermined amount larger than the first predetermined amount and repeating steps b) and c); and

g) repeating steps d), e), and f) until the detected response potential is determined to be a maximal response potential.

10. The method of claim 9, wherein step f) further comprises verifying that the increased stimulus intensity corresponds to detecting an increased response potential in response to the increased stimulus intensity.

11. The method of claim 1, wherein the body portion is at least one of a hand and wrist.

12. The method of claim 11, wherein the method further comprises attaching a stimulus unit to the hand and wrist, the stimulus unit comprising at least two stimulus electrodes for providing stimulus to the body portion and at least two sensing electrodes for sensing the response potential.

13. The method of claim 11, wherein the nerve is at least one of a median nerve and an ulnar nerve.

14. The method of claim 12, wherein the method further comprises measuring a separation of the at least two stimulus electrodes and the at least two sensing electrodes, following the attaching.

15. The method of claim 14, wherein the measuring is performed using a distance measurement member coupled to a part of the stimulus unit.

16. The method of claim 15, wherein the distance measurement member comprises an elongate strip having indicia for indicating the separation.

17. The method of claim 1, wherein the body portion is at least one of a leg, ankle and foot.

18. The method of claim 17, wherein the method further comprises attaching a stimulus unit to the leg and ankle, the stimulus unit comprising at least two stimulus electrodes for providing stimulus to the body portion and at least two sensing electrodes for sensing the response potential.

19. The method of claim 17, wherein the nerve is the sural nerve.

20. The method of claim 18, wherein the method further comprises measuring a separation of the at least two stimulus electrodes and the at least two sensing electrodes, following the attaching.

21. The method of claim 20, wherein the measuring is performed using a distance measurement member coupled to a part of the stimulus unit.

22. The method of claim 21, wherein the distance measurement member comprises an elongate strip having indicia for indicating the separation.

23. A method of automatic nerve stimulus, comprising:

a) determining a stimulus intensity at which to provide a stimulus to a body portion adjacent a nerve;

b) stimulating the body portion with the stimulus at the stimulus intensity;

c) detecting a response potential of the body portion in response to the stimulus;

d) reducing the stimulus intensity by a first predetermined amount and repeating steps b) and c);

e) verifying that the reduced stimulus intensity corresponds to detecting a reduced response potential in response to the reduced stimulus intensity;

f) increasing the stimulus intensity by a second predetermined amount larger than the first predetermined amount and repeating steps b) and c); and

g) repeating steps d), e), and f until the detected response potential is determined to be a maximal response potential.

24. The method of claim 23, wherein step f) further comprises verifying that the increased stimulus intensity corresponds to detecting an increased response potential in response to the increased stimulus intensity.

25. Computer readable storage storing computer program instructions which, when executed by a computerized testing apparatus, cause the computerized testing apparatus to perform the method of:

repeatedly stimulating a body portion adjacent a nerve at an increasing stimulus intensity;

detecting a response potential in response to each stimulation of the body portion;

determining a plurality of averaged responses based on the detected response potentials, each averaged response being an average of a set of at least two consecutive response potentials, each set of response potentials having at least one response potential not in another set;

determining at least two parameters of each averaged response;

determining that a maximal stimulus intensity has been reached when the respective at least two parameters of at least two averaged responses are within a predetermined range; and

determining the operable stimulus intensity as a predetermined proportion of the maximal stimulus intensity.

26. The computer readable storage of claim 25, wherein the steps of stimulating and detecting comprise:

a) determining a stimulus intensity at which to provide a stimulus to the body portion;

b) stimulating the body portion with the stimulus at the stimulus intensity; and

c) detecting the response potential of the body portion in response to the stimulus.

27. The computer readable storage of claim 26, wherein the steps of stimulating and detecting further comprise:

d) reducing the stimulus intensity by a first predetermined amount and once repeating steps b) and c);

e) verifying that the reduced stimulus intensity corresponds to detecting a reduced response potential in response to the reduced stimulus intensity;

f) increasing the stimulus intensity by a second predetermined amount larger than the first predetermined amount and repeating steps b) and c); and

g) repeating steps d), e), and f until the detected response potential is determined to be a maximal response potential.

28. A system for determining an operable stimulus intensity for nerve conduction testing, comprising:

a stimulator for stimulating a body portion adjacent a nerve and detecting a response to stimulation of the body portion;

a control module for controlling the stimulator; and

memory storing program instructions and accessible by the control module, wherein, when the program instructions are executed by the control module, the control module and stimulator are caused to;

repeatedly stimulate the body portion at an increasing stimulus intensity;

detect a response potential in response to each stimulation of the body portion;

determine a plurality of averaged responses based on the detected response potentials, each averaged response being an average of a set of at least two consecutive response potentials, each set of response potentials having at least one response potential not in another set;

determine at least two parameters of each averaged response;

determine that a maximal stimulus intensity has been reached when the respective at least two parameters of at least two averaged responses are within a predetermined range; and

determine the operable stimulus intensity as a predetermined proportion of the maximal stimulus intensity.

29. The system of claim 28, wherein the predetermined proportion is about 110%.

30. The system of claim 28, wherein the predetermined range is a percentage range of 0 to 20%.

31. The system of claim 28, wherein the at least two averaged responses comprise three averaged responses.

32. The system of claim 28, wherein the at least two averaged responses are consecutive averaged responses.

33. The system of claim 28, wherein the at least two parameters are selected from the group consisting of:

onset time, peak amplitude and the area of the response potential between peak amplitude and onset.

34. The system of claim 28, wherein each averaged response comprises an average of three consecutive response potentials.

35. The system of claim 28, wherein the stimulating and detecting comprise:

a) determining a stimulus intensity at which to provide a stimulus to a body portion adjacent a nerve;

b) stimulating the body portion with the stimulus at the stimulus intensity; and

c) detecting a response potential of the body portion in response to the stimulus.

36. The system of claim 35, wherein the stimulating and detecting further comprise:

d) reducing the stimulus intensity by a first predetermined amount and repeating steps b) and c);

e) verifying that the reduced stimulus intensity corresponds to detecting a reduced response potential in response to the reduced stimulus intensity;

f) increasing the stimulus intensity by a second predetermined amount larger than the first predetermined amount and repeating steps b) and c); and

g) repeating steps d), e), and f until the detected response potential is determined to be a maximal response potential.

37. The system of claim 36, wherein step f further comprises verifying that the increased stimulus intensity corresponds to detecting an increased response potential in response to the increased stimulus intensity.

38. The system of claim 28, wherein the body portion is at least one of a hand and wrist.

39. The system of claim 28, wherein the nerve is at least one of a median nerve and an ulnar nerve.

40. The system of claim 28, further comprising a distance measurement member coupled to the stimulator for measuring a separation of stimulus electrodes and sensing electrodes on the stimulator.

41. The system of claim 28, wherein the body portion is at least one of a leg, ankle and foot.

42. The system of claim 28, wherein the nerve is a sural nerve.

43. A system for automatic nerve stimulus, comprising:

a stimulator for stimulating a body portion adjacent a nerve and detecting a response to stimulation of the body part;

a control module for controlling the stimulator; and

memory storing program instructions and accessible by the control module, wherein, when the program instructions are executed by the control module, the control module and stimulator are caused to;

a) determine a stimulus intensity at which to provide a stimulus to the body portion;

b) stimulate the body portion with the stimulus at the stimulus intensity;

c) detect a response potential of the body portion in response to the stimulus;

d) reduce the stimulus intensity by a first predetermined amount and repeat steps b) and c);

e) verify that the reduced stimulus intensity corresponds to detecting a reduced response potential in response to the reduced stimulus intensity;

f) increase the stimulus intensity by a second predetermined amount larger than the first predetermined amount and repeat steps b) and c); and

g) repeat steps d), e), and f until the detected response potential is determined to be a maximal response potential.

44. The system of claim 43, wherein step f further comprises verifying that the increased stimulus intensity corresponds to detecting an increased response potential in response to the increased stimulus intensity.