Electromyography system

• US 20070293782A1
• Filed: 08/21/2007
• Published: 12/20/2007
• Est. Priority Date: 11/24/1999
• Status: Active Grant

• Current Assignee: Nuvasive Incorporated
• Original Assignee: NU Vasive Incorporated
• Inventors: Marino, James
• Granted Patent: US 8,562,539 B2
• Time in Patent Office: Days
• US Class Current: 600/546
• 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

A method of determining relative neuro-muscular response onset value thresholds for a plurality of spinal nerves, comprising: depolarizing a portion of the patient'"'"'s cauda equina; and measuring the current intensity level at which a neuro-muscular response to the depolarization of the cauda equina is detected in each of the plurality of spinal nerves. A method for detecting the presence of a nerve adjacent the distal end of at least one probe, comprising: determining relative neuro-muscular response onset values for a plurality of spinal nerves; emitting a stimulus pulse from a probe or surgical tool; detecting neuro-muscular responses to the stimulus pulse in each of the plurality of spinal nerves; and concluding that the electrode disposed on the distal end of the at least one probe is positioned adjacent to a first spinal nerve when the neuro-muscular response detected in the first spinal nerve is detected as a current intensity level less than or equal to a corresponding neuro-muscular response onset value of the first spinal nerve.

Claims

1. A method of determining at least one of a change in nerve status and a change in nerve proximity, comprising the steps of:

(a) applying a first stimulus signal to a stimulus electrode located a distance from a nerve;

(b) detecting an EMG response generated by a muscle physiologically coupled to said nerve in response to said first stimulus signal;

(c) increasing said first stimulus signal and repeating steps (a) and (b) until said detected EMG response reaches a predetermined minimum EMG value representing an evoked muscle action potential;

(d) identifying the level of said first stimulus signal required to obtain said predetermined minimum EMG value;

(e) repeating steps (a) through (d) with a second stimulus signal to identify the level of said second stimulus signal required to obtain said predetermined minimum EMG value; and

(f) determining at least one of a change in nerve status and a change in nerve proximity based on a comparison of said first stimulus signal level and said second stimulus signal level required to obtain said predetermined minimum EMG value.

2. The method of claim 1 and further, wherein said first and second stimulus signals each have a fixed current level.

3. The method of claim 1 and further, wherein said stimulus electrode is coupled to a medical device.

4. The method of claim 3 and further, wherein said medical device includes at least one of a cannula, a pedicle probe, a needle, a catheter, RF ablation device and a medical laser.

5. The method of claim 1 and further, wherein said EMG response is detected through the use of at least one EMG electrode.

6. The method of claim 5 and further, wherein said at least one EMG electrode comprises at least one of a needle electrode disposed within said muscle and a surface electrode located above said muscle.

7. The method of claim 1 and further, wherein step (c) includes the sub-steps of measuring a magnitude of said detected EMG response and comparing said magnitude with said predetermined minimum EMG value.

8. An article of manufacture for use in determining at least one of a change in nerve status and a change in nerve proximity, the article of manufacture comprising computer readable storage media including program logic embedded therein that causes control circuitry to perform the steps of:

(a) applying a first stimulus signal to a stimulus electrode located a distance from a nerve;

(b) detecting an EMG response generated by a muscle physiologically coupled to said nerve in response to said first stimulus signal;

(c) increasing said first stimulus signal and repeating steps (a) and (b) until said detected EMG response reaches a predetermined minimum EMG value representing an evoked muscle action potential;

(d) identifying the level of said first stimulus signal required to obtain said predetermined minimum EMG value;

(e) repeating steps (a) through (d) with a second stimulus signal to identify the level of said second stimulus signal required to obtain said predetermined minimum EMG value; and

(f) determining at least one of a change in nerve status and a change in nerve proximity based on a comparison of said first stimulus signal level and said second stimulus signal level required to obtain said predetermined minimum EMG value.

9. The article of manufacture of claim 8 and further, wherein said first and second stimulus signals each have a fixed current level.

10. The article of manufacture of claim 8 and further, wherein said stimulus electrode is coupled to a medical device.

11. The article of manufacture of claim 10 and further, wherein said medical device may comprise at least one of a cannula, a pedicle probe, a needle, a catheter, an RF ablation device and a medical laser.

12. The article of manufacture of claim 8 and further, wherein said EMG response is detected through the use of at least one EMG electrode.

13. The article of manufacture of claim 12 and further, wherein said at least one EMG electrode comprises at least one of a needle electrode disposed within said muscle and a surface electrode disposed above said muscle.

14. The article of manufacture of claim 8 and further, wherein step (c) includes the sub-steps of measuring a magnitude of said detected EMG signal and comparing said magnitude with said with said predetermined minimum EMG value.

15. An apparatus for determining at least one of a change in nerve status and a change in nerve proximity, comprising:

means for applying a first stimulus signal to a stimulus electrode located a distance from a nerve;

means for detecting an EMG response generated by a muscle physiologically coupled to said nerve in response to said first stimulus signal;

means for increasing said first stimulus signal until said detected EMG response reaches a predetermined minimum EMG value;

means for identifying the level of said first stimulus signal required to obtain said predetermined minimum EMG value;

means for applying a second stimulus signal to said stimulus electrode;

means for detecting an EMG response generated by a muscle physiologically coupled to said nerve in response to said second stimulus signal;

means for increasing said second stimulus signal until said detected EMG response reaches said predetermined minimum EMG value;

means for identifying the level of said second stimulus signal required to obtain said predetermined minimum EMG value; and

means for determining at least one of a change in nerve status and a change in nerve proximity based on a comparison of said first stimulus signal level and said second stimulus signal level required to obtain said predetermined minimum EMG value.

16. The apparatus of claim 15 and further, wherein said first and second stimulus signals each have a fixed current level.

17. The apparatus of claim 15 and further, wherein said stimulus electrode is coupled to a medical device.

18. The apparatus of claim 17 and further, wherein said medical device comprises at least one of a cannula, a pedicle probe, a needle, a catheter, an RF ablation device and a medical laser.

19. The apparatus of claim 15 and further, wherein said EMG response is detected through the use of at least one EMG electrode.

20. The apparatus of claim 19 and further, wherein said at least EMG electrode comprises at least one of a needle electrode disposed within said muscle and a surface electrode disposed above said muscle.

21. The apparatus of claim 15 and further, wherein said means for increasing includes means for measuring a magnitude of said detected EMG response and comparing said magnitude with said predetermined minimum EMG value.