System and methods for determining nerve proximity, direction, and pathology during surgery

• US 8,068,912 B2
• Filed: 01/09/2004
• Issued: 11/29/2011
• Est. Priority Date: 07/11/2001
• Status: Active Grant

• Current Assignee: Nuvasive Incorporated
• Original Assignee: Nuvasive Incorporated
• Inventors: Blewett, Jeffrey, Kaula, Norbert, Gharib, James, Farquhar, Allen
• Primary Examiner(s): Kahelin; Michael
• Application Number:
  US10/754,899
• Publication Number:
  US 20050182454A1
• Time in Patent Office: 2,881 Days
• Field of Search: 607/48, 600/554
• US Class Current: 607/48
• CPC Class Codes: A61B 17/00 Surgical instruments, devices or methods, e.g. tourniquets A61B18/00 takes precedence; contraceptive devices, pessaries, or applicators therefor A61F6/00; eye surgery A61F9/007; ear surgery A61F11/00
• CPC Class Codes: A61B 17/02 for holding wounds open; Tractors specula A61B1/32 ; drainage appliances for wounds A61M27/00
• CPC Class Codes: A61B 18/00 Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body eye surgery A61F9/007; ear surgery A61F11/00
• CPC Class Codes: A61B 2017/00039 Electric or electromagnetic phenomena other than conductivity, e.g. capacity, inductivity, Hall effect
• CPC Class Codes: A61B 5/1106 to assess neuromuscular blockade, e.g. to estimate depth of anaesthesia
• CPC Class Codes: A61B 5/389 Electromyography [EMG]
• CPC Class Codes: A61B 5/395 Details of stimulation, e.g. nerve stimulation to elicit EMG response
• CPC Class Codes: A61B 5/4893 Nerves
• CPC Class Codes: A61B 5/7217 of noise originating from a therapeutic or surgical apparatus, e.g. from a pacemaker
• CPC Class Codes: A61B 5/743 Displaying an image simultaneously with additional graphical information, e.g. symbols, charts, function plots
• CPC Class Codes: A61N 1/08 Arrangements or circuits for monitoring, protecting, controlling or indicating for external stimulators A61N1/3603; for implantable neurostimulators A61N1/36128; for heart stimulators A61N1/37; for defibrillators A61N1/3925
• CPC Class Codes: A61N 1/36 for stimulation
• CPC Class Codes: A61N 1/36017 with leads or electrodes penetrating the skin

Abstract

The present invention involves systems and methods for determining nerve proximity, nerve direction, and pathology relative to a surgical instrument based on an identified relationship between neuromuscular responses and the stimulation signal that caused the neuromuscular responses.

Claims

1. A non-transient computer-readable medium storing a software application executable by a processor and comprising instructions that, when executed by the processor, cause the following functions to be performed:

(a) deliver a plurality of stimulation current signals to tissue including or adjacent to a spinal nerve,

(b) in response to delivery of each one of the plurality of stimulation current signals, receive a plurality of voltage response values detected by a plurality of leg muscle sensor electrodes coupled to different leg muscles,

(c) determine the value of an unknown threshold nerve stimulation current amplitude required to evoke a threshold voltage response from at least one of the leg muscles using the steps of;

bracketing the unknown threshold nerve stimulation current amplitude by determining a first stimulation current amplitude that does not evoke the threshold voltage response from any of the leg muscles and a second stimulation current amplitude that does evoke the threshold voltage response from at least one of the leg muscles,

repeatedly bisecting the bracket that includes the threshold nerve stimulation current amplitude until a final bracket of a predetermined width is reached, and

selecting the threshold nerve stimulation current amplitude from the final bracket;

(d) determine which range from a predetermined group of ranges the determined threshold nerve stimulation current amplitude is located in; and

(e) display the determined threshold nerve stimulation current amplitude in units of mA on a display device along with a color-coded indicator corresponding to the determined range from the predetermined group of ranges.

2. The computer-readable medium storing a software application of claim 1, with further instructions to receive user commands.

3. The computer-readable medium storing a software application of claim 1 with further instructions, to activate a nerve proximity determination mode.

4. The computer-readable medium storing a software application of claim 1, with further instructions to activate a nerve direction determination mode.

5. The computer-readable medium storing a software application of claim 1, with further instructions to activate a nerve pathology determination mode.

6. The computer-readable medium storing a software application of claim 1, with further instructions that cause the display device to display the numerical value of the determined threshold nerve stimulation current amplitude along with one of three different color coded indicators.

7. The computer-readable medium storing a software application of claim 6, wherein the determined nerve stimulation current amplitude is selected as the midpoint of the final bracket.

8. The computer-readable medium storing a software application of claim 1, with further instructions that cause the display device to display at least one of a name and a symbol representative of an instrument being used to deliver the plurality of electrical current signals.

9. The computer-readable medium storing a software application of claim 1, with further instructions that cause the display device to display locations of nerves and muscles.

10. The computer-readable medium storing a software application of claim 1, with further instructions that cause the display device to display locations of the plurality of the leg muscle sensor electrodes.

11. The computer-readable medium storing a software application of claim 1, wherein the color-coded indicator on the display device corresponds with the range in which the determined threshold stimulation current amplitude is located so as to indicate nerve proximity between a surgical instrument and the spinal nerve.

12. The computer-readable medium storing a software application of claim 1, with further instructions to determine a maximum frequency of stimulation current pulses.

13. The computer-readable medium storing a software application of claim 11, wherein the group of predetermined ranges includes three ranges and the color-coded indicator on the display device is displayed as a different color for each of the three predetermined ranges.

14. The computer-readable medium storing a software application of claim 13, wherein the color-coded indicator on the display device is displayed as one of red, yellow, and green depending on the range in which the determined threshold stimulation current amplitude is located.

15. The computer-readable medium storing a software application of claim 9, wherein the display device displays the location of nerves and muscles within a graphical representation of a human.

16. The computer-readable medium storing a software application of claim 10, wherein the display device displays the location of said sensors within a graphical representation of a human.

17. The computer-readable medium storing a software application of claim 1, wherein said threshold voltage response is a peak-to-peak voltage of approximately 100 μ

V.

18. The computer-readable medium storing a software application of claim 1, wherein the threshold voltage response is a peak-to-peak voltage with peaks at a time T₁ and a time T₂ relative to a stimulation delivery time.

19. A non-transient computer-readable medium storing a software application executable by a processor and comprising instructions that, when executed by the processor, cause the following functions to be performed:

(a) deliver a plurality of stimulation signals to tissue including or adjacent to a nerve (b) in response to delivery of each one of the plurality of stimulation current signals, receive a plurality of voltage response values detected by a plurality of leg muscle sensor electrodes coupled to different leg muscles, (c) determine the value of an unknown threshold nerve stimulation value required to evoke a threshold voltage response that is a predetermined peak-to-peak voltage from at least one of the leg muscles using the steps of bracketing the unknown threshold nerve stimulation value by determining a first stimulation value that does not evoke the threshold voltage response from any of the leg muscles and a second stimulation value that does evoke the threshold voltage response from at least one of the leg muscles, repeatedly bisecting the bracket that includes the threshold nerve stimulation value until a final bracket of a predetermined width is reached, and selecting the threshold nerve stimulation value from the final bracket;

(d) determine which range from a predetermined group of ranges the determined threshold nerve stimulation is located in; and

(e) display a numerical representation of the determined threshold nerve stimulation value on a display device along with a color-coded indicator corresponding to the determined range from the predetermined group of ranges.

20. A non-transient computer-readable medium storing a software application-executable by a processor and comprising instructions that, when executed by the processor, cause the following functions to be performed:

(a) deliver a plurality of stimulation signals to an electrode on an instrument positioned within tissue of a patient that contains a spinal nerve, (b) in response to delivery of each one of the plurality of stimulation current signals, receive a plurality of voltage response values detected by a plurality of leg muscle sensors coupled to different leg muscles, (c) determine the value of an unknown threshold nerve stimulation amplitude required to evoke a threshold response from any of the leg muscles using the steps of bracketing the unknown threshold nerve stimulation amplitude by determining a first stimulation amplitude that does not evoke the threshold response from any of the leg muscles and a second stimulation amplitude that does evoke the threshold response from at least one of the leg muscles, repeatedly bisecting the bracket that includes the threshold nerve stimulation amplitude until a final bracket of a predetermined width is reached, and selecting the threshold nerve stimulation amplitude from the final bracket, (d) determine which range from a predetermined group of ranges the determined threshold nerve stimulation amplitude is located in, and (e) communicate on a display an indicator corresponding to the determined range from the predetermined group of ranges as an indicator of nerve proximity to the instrument.

21. The computer-readable medium storing a software application of claim 20, wherein the indicator corresponding to the determined range from the predetermined group of ranges includes a color display.

22. The computer-readable medium storing a software application of claim 21, wherein the predetermined group of ranges includes three predetermined ranges and the color displayed is one of three different colors, each of the three different colors corresponding to one of the three predetermined ranges.

23. The computer-readable medium storing a software application of claim 22, wherein the color is one of red, yellow, and green depending on the applicable range.

24. The computer-readable medium storing a software application of claim 20, with further instructions that cause the display to display at least one of a name and a symbol representative of the instrument being used.

25. The computer-readable medium storing a software application of claim 20, wherein the threshold response is a voltage response of a predetermined peak-to-peak voltage.

26. The computer-readable medium storing a software application of claim 25, wherein the predetermined peak-to-peak voltage is approximately 100 μ

V.