METHOD AND APPARATUS FOR QUANTITATIVE NERVE LOCALIZATION

• US 20090299214A1
• Filed: 05/29/2009
• Published: 12/03/2009
• Est. Priority Date: 05/11/2007
• Status: Active Grant

• Current Assignee: Neurometrix, Inc.
• Original Assignee: Neurometrix, Inc.
• Inventors: Wu, Changwang, Gozani, Shai, Kong, Xuan
• Granted Patent: US 9,042,978 B2
• 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
• CPC Class Codes: A61N 1/0456 Specially adapted for transcutaneous electrical nerve stimulation [TENS]
• CPC Class Codes: A61N 1/0502 Skin piercing electrodes
• CPC Class Codes: A61N 1/36021 for treatment of pain
• CPC Class Codes: A61N 1/37211 Means for communicating with stimulators

Abstract

A method for localizing a needle to a nerve, the method comprising:

• • using the needle to electrically stimulate the nerve, with a known current intensity, so as to evoke a nerve response;
  • detecting the nerve response;
  • analyzing the detected nerve response so as to identify at least one attribute of the same; and
  • confirming that the needle is in the immediate proximity of the nerve based upon known current intensity and at least one identified attribute of the detected nerve response.

Claims

1. A method for localizing a needle to a nerve, the method comprising:

using the needle to electrically stimulate the nerve, with a known current intensity, so as to evoke a nerve response;

detecting the nerve response;

analyzing the detected nerve response so as to identify at least one attribute of the same; and

confirming that the needle is in the immediate proximity of the nerve based upon known current intensity and at least one identified attribute of the detected nerve response.

2. A method according to claim 1 wherein the confirmed immediate proximity of needle to nerve is such that injection of a pharmacologically-active agent is clinically effective.

3. A method according to claim 1 wherein the needle is a hypodermic needle.

4. A method according to claim 1 wherein the needle is a hypodermic needle that is electrically insulated up to its tip.

5. A method according to claim 1 wherein the nerve is electrically stimulated using the needle and a surface electrode.

6. A method according to claim 1 wherein the nerve is electrically stimulated using a bi-polar needle.

7. A method according to claim 1 wherein the at least one identified attribute used to predict the proximity of the needle to the nerve comprises the amplitude of the nerve response.

8. A method according to claim 7 wherein the nerve response is rectified prior to measurement of the amplitude.

9. A method according to claim 1 wherein the at least one identified attribute used to predict the proximity of the needle to the nerve comprises the threshold response of the nerve to a specified amplitude.

10. A method according to claim 9 wherein the immediate proximity of needle to nerve is confirmed by a threshold nerve response at a stimulation current in a pre-determined range.

11. A method according to claim 10 wherein the pre-determined stimulation current range is 0.2 to 0.5 mA.

12. A method according to claim 11 wherein the pre-determined stimulation current range is based on a 100 μ

sec stimulation pulse duration.

13. A method according to claim 10 wherein the pre-determined stimulation current range is modified if the test subject is determined to have a neuropathy.

14. A method according to claim 13 wherein said current modification is performed automatically based on at least one identified nerve response attribute.

15. A method according to claim 11 wherein the lowest stimulation current within the pre-determined stimulation current range is determined.

16. A method according to claim 15 wherein the said lowest stimulation current is automatically determined based on at least one identified nerve response attribute.

17. A method according to claim 1 wherein the intensity of the electrical stimulus applied to the test subject is automatically controlled in accordance with at least one identified attribute of the desired nerve response.

18. A method according to claim 1 wherein the intensity of the electrical stimulus applied to the test subject is automatically controlled by:

(1) delivering an electrical stimulus to the nerve, and detecting and analyzing the nerve response;

(2) if the amplitude of the nerve response exceeds a pre-determined threshold, decreasing the intensity of the electrical stimulus;

(3) if the amplitude of the nerve response is below a pre-determined threshold, increasing the intensity of the electrical stimulus;

(4) repeating steps 1-3 until the changes in the intensity of the electrical stimulus are smaller than a pre-determined range;

(5) if the intensity of the electrical stimulus is higher than a target current range, alerting a user that the needle is not in the immediate vicinity of the nerve; and

(6) if the intensity of the electrical stimulus is within a target current range, alerting a user that the needle is in the immediate vicinity of the nerve; and

(7) if the intensity of the electrical stimulus is below a target current range, alerting a user that the needle may be in physical contact with the nerve.

19. A method according to claim 18 wherein the pre-determined range in step (4) is 0.1 mA.

20. A method according to claim 18 wherein the electrical stimulus has a repetition rate of 1 Hz.

21. A method according to claim 18 wherein the electrical stimulus has a repetition rate in the range of 2 Hz.

22. A method according to claim 18 wherein the target current is approximately 0.2 mA to approximately 0.5 mA.

23. A method according to claim 1 further comprising:

detecting neuropathies in the nerve based upon at least one identified attribute of the detected nerve response.

24. A method according to claim 23 wherein the at least one identified attribute used to detect neuropathy in the nerve comprises the amplitude of the nerve response.

25. A method according to claim 23 wherein the at least one identified attribute used to detect neuropathy in the nerve comprises the time delay between the application of the electrical stimulus to a subject and the detection of the nerve response onset.

26. A method according to claim 1 wherein a nerve response is detected at a single location.

27. A method according to claim 1 wherein nerve responses are detected at a plurality of locations.

28. A method according to claim 27 wherein the detection of the nerve responses at a plurality of locations is synchronized.

29. A method according to claim 1 wherein at least one of the detected nerve responses and the at least one identified attribute of the detected nerve response is logged.

30. A method according to claim 29 wherein the stimulation current intensity is also logged.

31. A method according to claim 1 wherein at least one of the detected nerve response and the at least one identified attribute of the detected nerve response is stored.

32. A method according to claim 31 wherein the stimulation current intensity is also stored.

33. A method according to claim 31 wherein storage occurs at a remote site.

34. A method for localizing a medical instrument to a nerve, the method comprising:

electrically stimulating the nerve using the medical instrument so as to evoke a nerve response;

detecting the nerve response;

analyzing the detected nerve response so as to identify at least one attribute of the same; and

estimating the proximity of the medical instrument to the nerve based upon known current intensity and at least one identified attribute of the detected nerve response.

35. A method according to claim 34 wherein estimating the proximity of the medical instrument to the nerve is desired so as to deliberately approach the nerve but not contact the nerve.

36. A method according to claim 35 wherein the medical instrument comprises a needle.

37. A method according to claim 35 wherein the medical instrument is used to deliver a pharmacologically-active agent to the nerve.

38. A method according to claim 34 wherein estimating the proximity of the medical instrument to the nerve is desired so as to avoid unintentionally contacting the nerve when performing a procedure in the proximity of the nerve.

39. A method according to claim 38 wherein the medical instrument comprises at least one from the group consisting of a needle, a probe, a sensor, a tissue separator, a cutting device, a biopsy device, a suturing device, a stapling device and an implant.

40. A method for localizing a needle to a nerve, the method comprising:

electrically stimulating the nerve, with a known current intensity, using the needle so as to evoke a nerve response;

detecting the nerve response;

analyzing the detected nerve response so as to identify at least one attribute of the same; and

estimating the proximity of the needle to the nerve based upon known current intensity and at least one identified attribute of the detected nerve response.

41. A method for determining information about a nerve, the method comprising:

positioning sensors at a plurality of locations on a test subject;

issuing a synchronization signal to each of the sensors so as to establish a common time reference for each of the sensors;

using at least one electrode to electrically stimulate the nerve;

using the sensors to generate a plurality of nerve traces, wherein each nerve trace is indicative of the nerve response at a given location; and

analyzing the plurality of nerve traces so as to determine at least one attribute for each nerve trace, and using the common time reference to place the determined attributes in proper time registration with one another.

42. Apparatus for localizing a needle to a nerve, the apparatus comprising:

an electrical stimulator connected to the needle for electrically stimulating the nerve, with a known current intensity, so as to evoke a nerve response;

at least one sensor for detecting the nerve response;

an analysis unit connected to the sensor for receiving the detected nerve response and identifying at least one attribute of the same; and

a localizing unit connected to the analysis unit for confirming that the needle is in the immediate proximity of the nerve based upon known current intensity and at least one identified attribute of the detected nerve response.

43. Apparatus according to claim 42 wherein the confirmed immediate proximity of needle to nerve is such that injection of a pharmacologically-active agent is clinically effective.

44. Apparatus according to claim 42 wherein the needle is a hypodermic needle.

45. Apparatus according to claim 42 wherein the at least one identified attribute used to predict the proximity of the needle to the nerve comprises the amplitude of the nerve response.

46. Apparatus according to claim 42 wherein the at least one identified attribute used to predict the proximity of the needle to the nerve comprises the threshold response of the nerve to a specified amplitude.

47. Apparatus according to claim 46 wherein the immediate proximity of needle to nerve is confirmed by a threshold nerve response at a stimulation current in a pre-determined range.

48. Apparatus according to claim 47 wherein the pre-determined stimulation current range is 0.2 to 0.5 mA.

49. Apparatus according to claim 48 wherein the pre-determined stimulation current range is based on a 100 μ

sec stimulation pulse duration.

50. Apparatus according to claim 47 wherein the pre-determined stimulation current range is modified if the test subject is determined to have a neuropathy.

51. Apparatus according to claim 50 wherein said current modification is performed automatically based on at least one identified nerve response attribute.

52. Apparatus according to claim 48 wherein the lowest stimulation current within the pre-determined stimulation current range is determined.

53. Apparatus according to claim 52 wherein the said lowest stimulation current is automatically determined based on at least one identified nerve response attribute.

54. Apparatus according to claim 42 wherein the intensity of the electrical stimulus applied to the test subject is automatically controlled in accordance with at least one identified attribute of the desired nerve response.

55. Apparatus according to claim 42 wherein the apparatus is configured so that the intensity of the electrical stimulus applied to the test subject is automatically controlled by:

(1) delivering an electrical stimulus to the nerve, and detecting and analyzing the nerve response;

(2) if the amplitude of the nerve response exceeds a pre-determined threshold, decreasing the intensity of the electrical stimulus;

(3) if the amplitude of the nerve response is below a pre-determined threshold, increasing the intensity of the electrical stimulus;

(4) repeating steps 1-3 until the changes in the intensity of the electrical stimulus are smaller than a pre-determined range;

(5) if the intensity of the electrical stimulus is higher than a target current range, alerting a user that the needle is not in the immediate vicinity of the nerve; and

(6) if the intensity of the electrical stimulus is within a target current range, alerting a user that the needle is in the immediate vicinity of the nerve; and

(7) if the intensity of the electrical stimulus is below a target current range, alerting a user that the needle may be in physical contact with the nerve.

56. Apparatus according to claim 55 wherein the pre-determined range in step (4) is 0.1 mA.

57. Apparatus according to claim 55 wherein the electrical stimulus has a repetition rate of 1 Hz.

58. Apparatus according to claim 55 wherein the electrical stimulus has a repetition rate in the range of 2 Hz.

59. Apparatus according to claim 55 wherein the target current is approximately 0.2 mA to approximately 0.5 mA.

60. Apparatus according to claim 42 further comprising:

a neuropathy detection unit for detecting neuropathies in the nerve based upon at least one identified attribute of the detected nerve response.

61. Apparatus according to claim 60 wherein the at least one identified attribute used to detect neuropathy in the nerve comprises the amplitude of the nerve response.

62. Apparatus according to claim 60 wherein the at least one identified attribute used to detect neuropathy in the nerve comprises the time delay between the application of the electrical stimulus to a subject and the detection of the nerve response onset.

63. Apparatus according to claim 42 wherein a nerve response is detected at a single location.

64. Apparatus according to claim 42 wherein nerve responses are detected at a plurality of locations.

65. Apparatus according to claim 64 wherein the detection of the nerve responses at a plurality of locations is synchronized.

66. Apparatus according to claim 42 wherein at least one of the detected nerve responses and the at least one identified attribute of the detected nerve response is logged.

67. Apparatus according to claim 66 wherein the stimulation current intensity is also logged.

68. Apparatus according to claim 42 wherein at least one of the detected nerve response and the at least one identified attribute of the detected nerve response is stored.

69. Apparatus according to claim 68 wherein the stimulation current intensity is also stored.

70. A method according to claim 68 wherein storage occurs at a remote site.

71. Apparatus for localizing a medical device to a nerve, the apparatus comprising:

an electrical stimulator connected to the medical device for electrically stimulating the nerve, with a known current intensity, so as to evoke a nerve response;

at least one sensor for detecting the nerve response;

an analysis unit connected to the sensor for receiving the detected nerve response and identifying at least one attribute of the same; and

a localizing unit connected to the analysis unit for confirming that the medical device is in the immediate proximity of the nerve based upon known current intensity and at least one identified attribute of the detected nerve response.

72. Apparatus according to claim 71 wherein estimating the proximity of the medical instrument to the nerve is desired so as to deliberately approach the nerve but not contact the nerve.

73. Apparatus according to claim 72 wherein the medical device comprises a needle.

74. Apparatus according to claim 72 wherein the medical device is used to deliver a pharmacologically-active agent to the nerve.

75. Apparatus according to claim 71 wherein estimating the proximity of the medical device to the nerve is desired so as to avoid unintentionally contacting the nerve when performing a procedure in the proximity of the nerve.

76. Apparatus according to claim 75 wherein the medical device comprises at least one from the group consisting of a needle, a probe, a sensor, a tissue separator, a cutting device, a biopsy device, a suturing device, a stapling device and an implant.

77. Apparatus for localizing a needle to a nerve, the apparatus comprising:

means for electrically stimulating the nerve, with a known current intensity, using the needle so as to evoke a nerve response;

means for detecting the nerve response;

means for analyzing the detected nerve response so as to identify at least one attribute of the same; and

means for estimating the proximity of the needle to the nerve based upon known current intensity and at least one identified attribute of the detected nerve response.

78. Apparatus for determining information about a nerve, the apparatus comprising:

sensors positioned at a plurality of locations on a test subject;

means for issuing a synchronization signal to each of the sensors so as to establish a common time reference for each of the sensors;

at least one electrode for electrically stimulating the nerve;

means connected to the sensors for generating a plurality of nerve traces, wherein each nerve trace is indicative of the nerve response at a given location; and

means for analyzing the plurality of nerve traces so as to determine at least one attribute for each nerve trace, and using the common time reference to place the determined attributes in proper time registration with one another.