System and methods for performing neurophysiologic assessments during spine surgery

Patent metadata

Field	Value
Publication number	US-9700228-B2
Application number	US-201615153703-A
Country	US
Kind code	B2
Filing date	May 12, 2016
Priority date	Feb 2, 2005
Publication date	Jul 11, 2017
Grant date	Jul 11, 2017

Abstract

A system and methods for performing neurophysiology assessments during surgery, such as assessing the health of the spinal cord via at least one of MEP and SSEP monitoring and assessing bone integrity, nerve proximity, neuromuscular pathway, and nerve pathology during spine surgery.

First claim

What is claimed is:

1. A system for performing neurophysiologic assessments during surgery, comprising:
a stimulator configured to deliver first and second sets of electrical stimulation signals to the motor cortex of a patient;
first and second sensors, each configured to detect at least one motor evoked potential response evoked by the first and second sets of electrical stimulation signals; and
a control unit in communication with the stimulator and the first and second sensors, the control unit being configured to (a) maintain first and second channels, said first channel associated with said first sensor and said second channel associated with said second sensor; (b) in response to a user input to initiate stimulation, direct transmission of the first and second sets of electrical stimulation signals, each of said first and second sets of electrical stimulation signals including stimulation signals having different electrical current amplitude, (c) receive evoked motor evoked potential response data from the first and second sensors, (d) determine a first lowest stimulation current amplitude for the first channel from the first set of electrical stimulation signals that evokes a motor evoked potential response greater than a threshold level, (e) determine a second lowest stimulation current amplitude for the second channel from the second set of electrical stimulation signals that evokes a motor evoked potential response greater than said threshold level, wherein determining the second lowest stimulation current amplitude is based at least in part on a determination of the lowest stimulation signal amplitude of the first set of stimulation signals that recruited on the second channel and the highest stimulation signal amplitude of the first set of stimulation signals that did not recruit on the second channel; and (f) communicate an onscreen assessment of a spinal cord health status to be displayed to a user in response to (d) and (e).

2. The system of claim 1 , wherein each of the first and second sets of electrical stimulation signals comprises a predetermined number of pulses separated by an interpulse gap, each pulse having a pulse width.

3. The system of claim 2 , wherein the number of pulses ranges from 1to 8 monophasic pulses, the interpulse gap ranges from 1 ms to 10 ms, and the pulse width ranges from 50 μs to 400 μs.

4. The system of claim 3 , wherein the monophasic pulses are positive phases pulses for all stimulation signals in the set of stimulation signals.

5. The system of claim 2 , wherein each of the first and second sets of electrical stimulation signals have amplitudes within a range from 0 milliamps to 1000 milliamps.

6. The system of claim 2 , wherein the control unit is configured to optimize at least one stimulation signal from the first and second sets of electrical stimulation signals at least one of before conducting a neurophysiologic assessment of the spinal cord and after a response to the stimulation signal stops being detected during the neurophysiologic assessment.

7. The system of claim 6 , wherein the control unit optimizes said at least one stimulation signal by modifying at least one of the number of pulses, the interpulse gap, the pulse width, and the current level before the neurophysiologic assessment of the spinal cord.

8. The system of claim 6 , wherein the onscreen assessment of the spinal cord health status is dependent upon at least one of the first lowest stimulation current amplitude and the second lowest stimulation current amplitude.

9. The system of claim 7 , wherein the onscreen assessment of the spinal cord health status communicated by the control unit comprises: (i) a numerical representation of at least one of the first lowest stimulation current amplitude and the second lowest stimulation current amplitude, and (ii) a color identifier to be displayed to a user.

10. The system of claim 1 , wherein the control unit is configured to perform a threshold hunting algorithm to identify at least one of the lowest first stimulation current amplitude and the second lowest stimulation current amplitude.

11. The system of claim 10 , wherein the threshold hunting algorithm is based on successive approximation from different stimulation current amplitudes.

12. The system of claim 11 , wherein the successive approximation involves: (a) establishing a bracket within which at least one of the first lowest stimulation current amplitude and the second lowest stimulation current amplitude is contained; and (b) successively bisecting the bracket until at least one of the first lowest stimulation current amplitude and the second lowest stimulation current amplitude is determined within a specified accuracy.

13. The system of claim 10 , wherein the control unit is configured to perform the threshold hunting algorithm for motor evoked potential responses from multiple muscle myotomes.

14. The system of claim 1 , further comprising a display in communication with the control unit for displaying the onscreen assessment of the spinal cord health status.

15. The system of claim 14 , wherein the display includes touch-screen control capabilities to allow a user to interface with the control unit.

16. The system of claim 15 , wherein the touch-screen control allows a user to at least one of select the parameters of the first and second sets of electrical stimulation signals and set a reminder to apply the stimulation signal at a specified time.

17. The system of claim 15 , wherein the display is configured to communicate at least one of a baseline motor evoked potential response threshold, a secondary motor evoked potential response threshold, and the difference between the baseline motor evoked potential response threshold and the secondary motor evoked potential response threshold.

18. The system of claim 1 , wherein the control unit is further configured to, in response to user input, transition into a manual mode in which the user selects a fixed stimulation current amplitude for a manual mode stimulation signal.

19. The system of claim 18 , wherein the controller, when transitioned to the manual mode, is configured to receive the selection of the fixed stimulation current amplitude for the manual mode stimulation signal and to communicate to the user whether or not a motor evoked potential response has been detected for the selected stimulation current amplitude.

20. The system of claim 1 , comprising a bite-block for placement in the patient's mouth.

21. The system of claim 20 , wherein the bite-block is in communication with the control unit and the control unit cannot generate a stimulation signal unless the bite-block is positioned within the patient's mouth.

22. The system of claim 21 , wherein the bite-block contains at least one electrode in communication with the control unit.

23. The system of claim 1 , comprising a second stimulator configured to deliver a third set of electrical stimulation signals to one or more nerves within the patient, the control unit being further configured to direct transmission of the third set of stimulation signals, (b) receive evoked neuromuscular response data from the first and second sensors in response to the third set of stimulation signals, (c) assess a status of at least one of bone integrity, nerve direction, nerve pathology, and neuromuscular pathway integrity by identifying a relationship between a third lowest stimulation current amplitude from the third set stimulation signals that evokes

Assignees

• Nuvasive Inc

Inventors

• Gharib James E
• Farquhar Allen
• Layman Doug

Classifications

• A61B5/7475

  User input or interface means, e.g. keyboard, pointing device, joystick · CPC title

• A61N1/37247

  User interfaces, e.g. input or presentation means · CPC title

• A61N1/0548

  Oral electrodes · CPC title

• A61B5/407 Primary

  Evaluating the spinal cord (for locating the epidural space A61B5/4896) · CPC title

• A61N1/36003

  of motor muscles, e.g. for walking assistance · CPC title