Electromyography system

• US 20080071191A1
• Filed: 10/31/2007
• Published: 03/20/2008
• Est. Priority Date: 11/24/1999
• Status: Abandoned Application

• Current Assignee: Nuvasive Incorporated
• Original Assignee: Nuvasive Incorporated
• Inventors: Owens, Jeffrey, Vaughn, Robin, Kelleher, Brian, Stone, Corbett, Marino, James
• Application Number:
  US11/981,893
• Publication Number:
  US 20080071191A1
• Time in Patent Office: Days
• 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

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 the relative proximity of a spinal nerve to an instrument while accessing a spinal target site during surgery, comprising,

(a) advancing said instrument toward said spinal target site through the body tissue of said patient;

(b) emitting from an electrode situated near a distal end of said instrument a stimulation signal of known intensity while concurrently monitoring for the presence of a resulting neuro-muscular response from at least one electromyography electrode positioned on the patient and configured to detect the electrical charge associated with muscle activity;

(c) varying the intensity of said stimulation signal until a neuromuscular response is detected;

(d) ceasing emission of said stimulation signal when said neuro-muscular response is detected;

(e) comparing the stimulation intensity level at which the neuro-muscular response was detected to a predetermined stimulation intensity level to indicate the relative proximity of said spinal nerve to said distal end of said instrument; and

(f) communicating to a user the determined relative proximity.

2. The method of claim 1, wherein said instrument is a surgical probe.

3. The method of claim 1, wherein said instrument is a surgical access instrument.

4. The system of claim 3, wherein said instrument is a cannula.

5. The method of claim 1, wherein the intensity level of the stimulation signal is incrementally varied.

6. The method of at least one of claims 1, wherein the intensity level of the stimulation signal is increased.

7. The method of claim 1, wherein said spinal nerve is one of a plurality of spinal nerves exiting from successive vertebrae.

8. The method of claim 1, wherein communicating to said operator involves at least one of visually and audibly indicating to said operator the intensity level of the stimulus signal that resulted in said neuro-muscular response.

9. The method of claim 8, wherein audibly indicating to said user involves sounding an alarm to indicate the relative proximity determined.

10. The method of claim 9, wherein the volume of the alarm is varied depending on the relative proximity determined.

11. The method of claim 9, wherein the frequency of the alarm is varied depending on the relative proximity determined.

12. The method of claim 8, wherein visually indicating to said user involves the step of displaying a color.

13. The method of claim 12, wherein the color is varied depending on the relative proximity of the nerve detected.

14. The method of claim 1, further comprising:

repeating steps (a)-(f) until said instrument reaches said spinal target site.