Electromyography system

• US 7,963,927 B2
• Filed: 04/21/2004
• Issued: 06/21/2011
• Est. Priority Date: 11/24/1999
• Status: Expired due to Fees

• Current Assignee: Nuvasive Incorporated
• Original Assignee: Nuvasive Incorporated
• Inventors: Owens, Jeffrey H., Vaughn, Robin H., Marino, James F., Stone, Corbett W., Kelleher, Brian S.
• Primary Examiner(s): Hindenburg; Max
• Assistant Examiner(s): SZMAL, BRIAN SCOTT
• Application Number:
  US10/830,189
• Publication Number:
  US 20040199084A1
• Time in Patent Office: 2,617 Days
• Field of Search: 600/546, 600/554, 600/545, 600/557, 606/79, 340/930, 128/901, 128/902, 128/908, 128/899, 128/897, 128/99.1, 128/653.1, 607/156
• US Class Current: 600/554
• CPC Class Codes: A61B 17/00234 for minimally invasive surgery A61B17/0218, A61B17/0469, A61B17/12013, A61B17/1285, A61B17/29, A61B17/320016 take precedence
• CPC Class Codes: A61B 2017/00022 Sensing or detecting at the treatment site
• CPC Class Codes: A61B 2017/00039 Electric or electromagnetic phenomena other than conductivity, e.g. capacity, inductivity, Hall effect
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/296 for electromyography [EMG]
• CPC Class Codes: A61B 5/389 Electromyography [EMG]
• CPC Class Codes: A61B 5/4893 Nerves

Abstract

An electromyography system and related method for performing automated screw test procedures, involving automatically determining an onset neuro-muscular response to the application of an electrical stimulus to a portion of pediculur bone and communicating to a user an onset electrical stimulus level which causes the onset neuro-muscular response.

Claims

1. A method of determining structural integrity of a bone within the spine of a patient using a neurophysiology system, the bone having a first aspect and a second aspect, said second aspect separated from said first aspect by a width and located adjacent to a spinal nerve, said method comprising:

applying an electrical stimulus to said first aspect of said bone;

electrically monitoring a plurality of leg muscle myotome locations via a plurality of electromyographic (EMG) sensor electrodes coupled to the leg muscle myotome locations, at least one of the leg muscle myotome locations being associated with said spinal nerve;

detecting an onset neuro-muscular response having an amplitude greater than a predetermined positive value in response to the application of said electrical stimulus to said first aspect of said bone by automatically increasing said electrical stimulus in constant increments until said onset neuro-muscular response is detected by one or more of the EMG sensor electrodes, wherein said automatic increasing is controlled by said neurophysiology system; and

displaying on an integrated display device of said neurophysiology system while viewed by a surgeon operating on the patient'"'"'s spine an onset electrical stimulus current level which causes said onset neuro-muscular response.

2. The method of claim 1, wherein the electrical stimulus is emitted from an electrode disposed on the distal end of an instrument inserted through a cannula extending toward said bone.

3. The method of claim 1, wherein automatically increasing said electrical stimulus in constant increments comprises applying a plurality of electrical stimulus pulses.

4. The method of claim 3, wherein the plurality of electrical stimulus pulses comprises current pulses that automatically increase in constant increments over time until said onset neuromuscular response is determined.

5. The method of claim 1, wherein the electrical stimulus is increased by constant current increments from within the range of 0.5 to 4 milliamps.

6. The method of claim 1, wherein the electrical stimulus is increased within a current range from 0.5 to 32.0 milliamps.

7. The method of claim 1, wherein said spinal nerve exits from successive vertebrae within the patient'"'"'s spine.

8. The method of claim 1, wherein said onset neuro-muscular response is an electromyography response from a muscle coupled to said spinal nerve.

9. The method of claim 1, wherein electrically monitoring said plurality of leg muscle myotome locations is performed through the use of needle electrodes electrically coupled to leg muscle myotomes.

10. The method of claim 1 and further, comprising audibly indicating to said surgeon an intensity level representing said onset electrical stimulus current level causing said onset neuro-muscular response for said spinal nerve.

11. The method of claim 10, wherein audibly indicating comprises sounding an alarm if said onset neuro-muscular response is detected at a predetermined intensity level.

12. The method of claim 10, further comprising varying the volume of said alarm according to variations in said intensity level of said onset electrical stimulus current level causing said onset neuro-muscular response.

13. The method of claim 12, wherein said volume of said alarm decreases as said intensity level of said onset electrical stimulus current level causing said neuro-muscular response increases.

14. The method of claim 13, further comprising varying the frequency of said alarm according to said intensity level of said onset electrical stimulus current level causing said onset neuro-muscular response.

15. The method of claim 14, wherein said frequency of said alarm decreases as said intensity level of said onset electrical stimulus current level causing said onset neuro-muscular response increases.

16. The method of claim 1, wherein said first aspect of said bone comprises a region within a pedicle in contact with a pedicle screw.

17. The method of claim 1, wherein applying an electrical stimulus to said first aspect of said bone comprises applying said electrical stimulus to a proximal end of a bone screw inserted into said first aspect of said bone.

18. The method of claim 1, wherein said predetermined positive value is a voltage value selected from a range of 60 mV to 80 mV.

19. A method of determining structural integrity of a bone within the spine of a patient using a neurophysiology system, the bone having a first aspect and a second aspect, said second aspect separated from said first aspect by a width and located adjacent to a spinal nerve, said method comprising:

applying an electrical stimulus to said first aspect of said bone;

electrically monitoring a plurality of leg muscle myotome locations via a plurality of electromyographic (EMG) sensor electrodes coupled to the leg muscle myotome locations, at least one of the leg muscle myotome locations being associated with said spinal nerve;

determining an onset neuro-muscular response to the application of said electrical stimulus to said first aspect of said bone by automatically increasing said electrical stimulus in constant increments until said onset neuro-muscular response is detected by one or more of the EMG sensor electrodes outputting an EMG signal having an amplitude value greater than a predetermined positive value, wherein said automatic increasing is controlled by said neurophysiology system; and

displaying on a display device of said neurophysiology system that is viewable by a surgeon operating on the patient'"'"'s spine an onset electrical stimulus current level which causes said onset neuro-muscular response, wherein displaying the onset electrical stimulus current level on the display device includes visually displaying to said surgeon, in response to determining said onset neuro-muscular response, an electrical current value representing said onset electrical stimulus current level causing said onset neuro-muscular response for said spinal nerve.

20. The method of claim 19, wherein visually displaying comprises illuminating lights.

21. The method of claim 19, wherein visually displaying comprises displaying one of three colors on the integrated display device when the electrical current value is below a predetermined level.

22. The method of claim 21, wherein each color corresponds to a predetermined warning to the surgeon.

23. The method of claim 19, wherein visually displaying involves the use of at least one of multi-color LEDs and an integrated display.

24. The method of claim 19, wherein the electrical stimulus is emitted from an electrode disposed on the distal end of an instrument inserted through a cannula extending toward said bone.

25. The method of claim 19, wherein automatically increasing said electrical stimulus in constant increments comprises applying a plurality of electrical stimulus pulses, wherein the plurality of electrical stimulus pulses comprises current pulses that automatically increase in constant increments over time until said onset neuromuscular response is determined.

26. The method of claim 19, wherein the electrical stimulus is increased by constant current increments from within the range of 0.5 to 4 milliamps.

27. The method of claim 19, wherein the electrical stimulus is increased within a current range from 0.5 to 32.0 milliamps.

28. The method of claim 19, wherein said onset neuro-muscular response is an electromyography response from a muscle coupled to said spinal nerve.

29. The method of claim 19, wherein electrically monitoring said plurality of leg muscle myotome locations is performed through the use of needle electrodes electrically coupled to leg muscle myotomes.

30. The method of claim 19, and further comprising audibly indicating to said surgeon an intensity level representing said onset electrical stimulus current level causing said onset neuro-muscular response for said spinal nerve.

31. The method of claim 30, wherein audibly indicating comprises sounding an alarm if said onset neuro-muscular response is detected at a predetermined intensity level.

32. The method of claim 30, further comprising varying the volume of said alarm according to variations in said intensity level of said onset electrical stimulus current level causing said onset neuro-muscular response.

33. The method of claim 32, wherein said volume of said alarm decreases as said intensity level of said onset electrical stimulus current level causing said neuro-muscular response increases.

34. The method of claim 33, further comprising varying the frequency of said alarm according to said intensity level of said onset electrical stimulus current level causing said onset neuro-muscular response.

35. The method of claim 34, wherein said frequency of said alarm decreases as said intensity level of said onset electrical stimulus current level causing said onset neuro-muscular response increases.

36. The method of claim 19, wherein said first aspect of said bone comprises a region within a pedicle in contact with a pedicle screw.

37. The method of claim 19, wherein applying an electrical stimulus to said first aspect of said bone comprises applying said electrical stimulus to a proximal end of a bone screw inserted into said first aspect of said bone.

38. The method of claim 19, wherein said amplitude value greater than the predetermined positive value comprises a peak-to-peak amplitude value greater than the predetermined positive value.

39. The method of claim 38, wherein said predetermined positive value is a voltage value selected from a range of 60 mV to 80 mV.

40. A method of determining structural integrity of a bone within the spine of a patient using a neurophysiology system, the bone having a first aspect and a second aspect, said second aspect separated from said first aspect by a width and located adjacent to a spinal nerve, said method comprising:

applying an electrical stimulus to said first aspect of said bone;

electrically monitoring a plurality of leg muscle myotome locations via a plurality of electromyographic (EMG) sensor electrodes coupled to the leg muscle myotome locations, at least one of the leg muscle myotome locations being associated with said spinal nerve;

determining an onset neuro-muscular response to the application of said electrical stimulus to said first aspect of said bone by automatically increasing said electrical stimulus in constant increments until said onset neuro-muscular response is detected by one or more of the EMG sensor electrodes outputting an EMG signal having an amplitude value greater than a predetermined positive value, wherein said amplitude value greater than the predetermined positive value comprises a peak-to-peak amplitude value greater than the predetermined positive value, wherein said automatic increasing is controlled by said neurophysiology system; and

in response to determining said onset neuro-muscular response, displaying on a display device of said neurophysiology system that is viewable by a surgeon operating on the patient'"'"'s spine an onset electrical stimulus current level which causes said onset neuro-muscular response.

41. The method of claim 40, wherein displaying the onset electrical stimulus current level on the display device includes visually displaying to said surgeon an electrical current value representing said onset electrical stimulus current level causing said onset neuro-muscular response for said spinal nerve.

42. The method of claim 40, wherein the electrical stimulus is emitted from an electrode disposed on the distal end of an instrument inserted through a cannula extending toward said bone.

43. The method of claim 40, wherein automatically increasing said electrical stimulus in constant increments comprises applying a plurality of electrical stimulus pulses, wherein the plurality of electrical stimulus pulses comprises current pulses that automatically increase in constant increments over time until said onset neuromuscular response is determined.

44. The method of claim 40, wherein the electrical stimulus is increased by constant current increments from within the range of 0.5 to 4 milliamps.

45. The method of claim 40, wherein the electrical stimulus is increased within a current range from 0.5 to 32.0 milliamps.

46. The method of claim 40, wherein said onset neuro-muscular response is an electromyography response from a muscle coupled to said spinal nerve.

47. The method of claim 40, wherein electrically monitoring said plurality of leg muscle myotome locations is performed through the use of needle electrodes electrically coupled to leg muscle myotomes.

48. The method of claim 40, and further comprising audibly indicating to said surgeon an intensity level representing said onset electrical stimulus current level causing said onset neuro-muscular response for said spinal nerve.

49. The method of claim 48, wherein audibly indicating comprises sounding an alarm if said onset neuro-muscular response is detected at a predetermined intensity level.

50. The method of claim 48, further comprising varying the volume of said alarm according to variations in said intensity level of said onset electrical stimulus current level causing said onset neuro-muscular response.

51. The method of claim 50, wherein said volume of said alarm decreases as said intensity level of said onset electrical stimulus current level causing said neuro-muscular response increases.

52. The method of claim 51, further comprising varying the frequency of said alarm according to said intensity level of said onset electrical stimulus current level causing said onset neuro-muscular response.

53. The method of claim 52, wherein said frequency of said alarm decreases as said intensity level of said onset electrical stimulus current level causing said onset neuro-muscular response increases.

54. The method of claim 40, wherein said first aspect of said bone comprises a region within a pedicle in contact with a pedicle screw.

55. The method of claim 40, wherein applying an electrical stimulus to said first aspect of said bone comprises applying said electrical stimulus to a proximal end of a bone screw inserted into said first aspect of said bone.

56. The method of claim 40, wherein said predetermined positive value is a voltage value selected from a range of 60 mV to 80 mV.