Electromyography system

• US 8,641,638 B2
• Filed: 10/31/2007
• Issued: 02/04/2014
• Est. Priority Date: 11/24/1999
• Status: Expired due to Term

• Current Assignee: Nuvasive Incorporated
• Original Assignee: Nuvasive Incorporated
• Inventors: Kelleher, Brian S., Marino, James F., Stone, Corbett W., Vaughn, Robin H., Owens, Jeffrey H.
• Primary Examiner(s): SZMAL, BRIAN SCOTT
• Application Number:
  US11/981,889
• Publication Number:
  US 20080064976A1
• Time in Patent Office: 2,288 Days
• Field of Search: 600/546, 600/554, 600/545, 600/587, 600/210, 600/373, 606/79, 606/170, 606/207, 606/83, 606/84, 606/90, 607/143, 607/116, 607/117, 340/930, 128/901, 128/902, 128/908, 604/164.11, 604/264, 604/272
• 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

Methods for determining structural integrity of a bone within the spine of a patient, the bone having a first aspect and a second aspect, wherein the second aspect separated from the first aspect by a width and located adjacent to a spinal nerve. The methods involve (a) applying an electrical stimulus to the first aspect of the bone; (b) electrically monitoring a muscle myotome associated with the spinal nerve to detect if an onset neuro-muscular response occurs in response to the application of the electrical stimulus to the first aspect of the bone; (c) automatically increasing the magnitude of the electrical stimulus to until the onset neuro-muscular response is detected; and (d) communicating to a user via at least one of visual and audible means information representing the magnitude of the electrical stimulus which caused the onset neuro-muscular response.

Claims

1. A method for testing the structural integrity of a spinal pedicle of a patient through a minimally invasive operative corridor to detect a defect in the structural integrity of a pedicle wall surrounding a pedicle screw path formed through the pedicle, said method comprising:

(a) advancing an elongate element to said pedicle via a minimally invasive approach through said patient;

(b) advancing a stimulation element through said elongate element to said pedicle, said stimulation element communicatively linked to a controller that directs application of an electrical stimulus;

(c) applying an electrical stimulus to said pedicle via said stimulation element;

(d) electrically monitoring with a sensor communicatively linked to said controller a muscle myotome associated with a spinal nerve lying adjacent to said pedicle to detect if an onset neuro-muscular response occurs in response to the application of said electrical stimulus;

(e) said controller automatically adjusting the magnitude of the electrical stimulus until said onset neuro-muscular response is detected, said controller determining the electrical stimulus magnitude that caused said onset neuro-muscular response;

(f) said controller interpreting the electrical stimulus magnitude which caused said onset neuro-muscular response and outputting an indicator indicative of the structural integrity of the pedicle; and

(g) redirecting the pedicle screw path when a defect in the structural integrity of the pedicle wall is indicated.

2. The method of claim 1, wherein said stimulation element comprises at least one of a probe and a surgical tool, and step (c) involves applying said electrical stimulus from an electrode disposed on the distal end of said at least one of a probe and surgical tool.

3. The method of claim 1, wherein said pedicle is disposed within one of the cervical, thoracic, and lumbar region of the patient'"'"'s spine.

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

5. The method of claim 1, wherein the sensor of step (d) is an EMG electrode electrically coupled to said muscle myotome.

6. The method of claim 1, wherein the indicator of step (f) is a visual indicator.

7. The method of claim 1 and further, wherein the indicator of step (f) is an audible indicator.

8. The method of claim 1, wherein step (c) involves applying said electrical stimulus to a proximal end of a pedicle screw inserted into said pedicle along said pedicle screw path.

9. The method of claim 1, wherein said elongate element comprises a cannula.

10. The method of claim 1, wherein the electrical stimulus comprises a plurality of current pulses.

11. The method of claim 10, wherein the plurality of current pulses are automatically increased in constant increments over time until said onset neuromuscular response is determined.

12. The method of claim 10, wherein the plurality of electrical stimulus pulses are increased incrementally within a range including a minimum stimulation current level and a maximum stimulation current intensity.

13. A method for performing pedicle integrity assessments with minimal tissue disruption to detect a defect in the structural integrity of a pedicle wall surrounding a pedicle screw path formed through the pedicle, said method comprising:

(a) advancing a minimally invasive cannula via a minimally invasive approach to a pedicle target site within a patient;

(b) delivering a stimulation signal to said pedicle target site via a stimulation element disposed through said cannula, said stimulation element communicatively linked to a controller that directs application of the electrical stimulus; and

(c) electrically monitoring with a sensor communicatively linked to said controller a muscle myotome innervated by a nerve adjacent to said pedicle to detect when an onset neuro-muscular response occurs in a muscle myotome innervated by said nerve in response to the delivery of said stimulation signal and determine the intensity level of the electrical stimulus that causes said onset neuro-muscular response;

(d) said controller interpreting the determined intensity level of the electrical stimulus that caused said onset neuro-muscular response and outputting at least one of visual and audible indicia indicative of the structural integrity of the pedicle; and

(e) redirecting the pedicle screw path when a defect in the structural integrity of the pedicle wall is indicated.

14. The method of claim 13, wherein step (b) comprises automatically increasing the intensity level of the stimulation signal until said onset neuro-muscular response is detected.

15. The method of claim 14, wherein step (b) further comprises delivering said stimulation signal as a plurality of electrical stimulus pulses that increase over time.

16. The method of claim 15, wherein the plurality of electrical stimulus pulses comprises current pulses varied incrementally within a range including a minimum stimulation current intensity and a maximum stimulation current intensity.

17. The method of claim 13, wherein said onset neuro-muscular response is an electromyography response from a muscle coupled to said nerves.

18. The method of claim 17, wherein said sensor is an EMG electrode electrically coupled to said muscle myotome.

19. The method of claim 13, wherein said pedicle target site is a proximal end of a pedicle screw implanted in said pedicle along said pedicle screw path.

20. The method of claim 13, wherein said pedicle is within one of the cervical, thoracic, and lumbar regions of the patient'"'"'s spine.

21. The method of claim 13, wherein said stimulation element comprises at least one of a probe and a surgical tool, and step (b) involves delivering said stimulation signal from an electrode disposed on the distal end of said at least one of a probe and surgical tool.

22. The method of claim 13, wherein step (d) involves visually indicating an intensity level of the stimulus that evoked the onset neuro-muscular response for said nerve and illuminating lights which correspond to predetermined warnings.

23. The method of claim 13, wherein step (d) involves sounding an alarm if said determined intensity level is less than a predetermined intensity level.