Neural monitoring system

• US 8,979,767 B2
• Filed: 11/14/2012
• Issued: 03/17/2015
• Est. Priority Date: 10/18/2007
• Status: Active Grant

• Current Assignee: Innovative Surgical Solutions, LLC (Johnson & Johnson)
• Original Assignee: Innovative Surgical Solutions, LLC (Johnson & Johnson)
• Inventors: Bartol, Stephen, Wybo, Christopher
• Primary Examiner(s): Dougherty, Sean
• Assistant Examiner(s): Stout, Michael C
• Application Number:
  US13/676,809
• Publication Number:
  US 20130072811A1
• Time in Patent Office: 853 Days
• Field of Search: 600/546, 600/554, 600/595
• US Class Current: 600/554
• CPC Class Codes: A61B 2505/05 Surgical care
• CPC Class Codes: A61B 2560/0276 Determining malfunction
• CPC Class Codes: A61B 2560/0412 Low-profile patch shaped housings
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/1104 induced by stimuli or drugs; A61B5/1102 takes precedence; investigating medicinal preparations G01N33/15
• CPC Class Codes: A61B 5/1106 to assess neuromuscular blockade, e.g. to estimate depth of anaesthesia
• CPC Class Codes: A61B 5/1107 Measuring contraction of parts of the body, e.g. organ, muscle apparatus for measuring work or force in general G01L
• 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 5/4029 for evaluating the peripheral nervous systems A61B5/24 takes precedence
• CPC Class Codes: A61B 5/4519 Muscles A61B5/389, A61B5/224 take precedence
• CPC Class Codes: A61B 5/4893 Nerves
• CPC Class Codes: A61B 5/6828 Leg
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61B 5/7217 of noise originating from a therapeutic or surgical apparatus, e.g. from a pacemaker
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives

Abstract

A neural monitoring system for determining a proximity between a stimulator and a nerve within an intracorporeal treatment area of a human subject includes a stimulator, a mechanical sensor, and a receiver. The stimulator is configured to extend within the intracorporeal treatment area and to provide an electrical stimulus therein. The mechanical sensor is configured to be placed in mechanical communication with the muscle and to generate a mechanomyography output signal corresponding to a sensed mechanical movement of the muscle. The receiver is configured to: receive the mechanomyography output signal from the mechanical sensor; receive an indication of a magnitude of the provided intracorporeal stimulus; determine a magnitude of acceleration of the muscle from the received mechanomyography output signal; and determine a proximity between the stimulator and the nerve from the magnitude of the provided intracorporeal stimulus and the magnitude of acceleration of the muscle.

Claims

1. A neural monitoring system for determining a distance between a stimulator and a nerve within an intracorporeal treatment area of a human subject, with the nerve innervating a muscle, the neural monitoring system comprising:

a stimulator configured to extend within the intracorporeal treatment area and to provide an electrical stimulus therein;

a mechanical sensor configured to be placed in mechanical communication with the muscle and to generate a mechanomyography output signal corresponding to a sensed mechanical movement of the muscle; and

a processor configured to;

receive the mechanomyography output signal from the mechanical sensor;

receive an indication of a magnitude of the provided intracorporeal stimulus;

determine a magnitude of acceleration of the muscle from the received mechanomyography output signal;

determine a distance between the stimulator and the nerve from the magnitude of the provided intracorporeal stimulus and the magnitude of acceleration of the muscle;

wherein the processor is configured to determine the distance by selecting a distance value from a lookup table stored in a memory associated with the processor; and

wherein the lookup table provides the distance value as a function of both a variable intracorporeal stimulus and a variable magnitude of acceleration of the muscle.

2. The neural monitoring system of claim 1, further comprising a display device in communication with the processor;

wherein the processor is configured to determine if the sensed mechanical movement of the muscle was caused by the provided stimulus and

wherein the processor is further configured to display an indication of the determined distance to a user via the display device if it is determined that the sensed mechanical movement of the muscle was caused by the provided stimulus.

3. The neural monitoring system of claim 1, wherein the processor is further configured to:

compute a time derivative of an acceleration of the muscle from the mechanomyography output signal;

compare the computed time derivative of acceleration to a jerk threshold; and

indicate that the sensed mechanical movement of the muscle was induced by the provided intracorporeal stimulus if the computed time derivative of acceleration exceeds the jerk threshold.

4. The neural monitoring system of claim 2, wherein the processor is further configured to:

compare the determined distance to a distance threshold; and

wherein the indication is a first indication if the determined distance is less than the distance threshold; and

wherein the indication is a second indication if the determined distance is greater than the distance threshold.

5. The neural monitoring system of claim 1, wherein the stimulator is an invasive medical instrument.

6. The neural monitoring system of claim 5, wherein the invasive medical instrument is a retractor.

7. The neural monitoring system of claim 5, wherein the invasive medical instrument is a screw.

8. The neural monitoring system of claim 1, wherein the mechanical sensor is in wireless data communication with the processor.

14. The system of claim 1, wherein the distance is expressed in millimeters.

9. A method of determining a distance between a stimulator and a nerve within an intracorporeal treatment area of a human subject, with the nerve innervating a muscle, the method comprising:

providing an electrical stimulus within the intracorporeal treatment area from a stimulator configured to extend within the intracorporeal treatment area;

receiving a mechanomyography output signal from a mechanical sensor in mechanical communication with the muscle, the mechanomyography output signal corresponding to a mechanical movement of the muscle sensed by the mechanical sensor;

receiving an indication of a magnitude of the provided intracorporeal stimulus;

determining a magnitude of acceleration of the muscle from the received mechanomyography output signal;

determining a distance between the stimulator and the nerve from the magnitude of the provided intracorporeal stimulus and the magnitude of acceleration of the muscle;

wherein determining the distance includes selecting a distance value from a lookup table stored in a memory associated with the processor; and

wherein the lookup table provides the distance value as a function of both a variable intracorporeal stimulus and a variable magnitude of acceleration of the muscle.

10. The method of claim 9, further comprising

determining if the sensed mechanical movement of the muscle was caused by the provided stimulus;

and

displaying an indication of the determined distance to a user via a display device if it is determined that the sensed mechanical movement of the muscle was caused by the provided stimulus.

11. The method of claim 9, further comprising:

computing a time derivative of an acceleration of the muscle from the mechanomyography output signal;

comparing the computed time derivative of acceleration to a jerk threshold; and

indicating that the sensed mechanical movement of the muscle was induced by the provided intracorporeal stimulus if the computed time derivative of acceleration exceeds the jerk threshold.

12. The method of claim 10, further comprising:

comparing the determined distance to a distance threshold; and

wherein the indication is a first indication if the determined distance is less than the distance threshold; and

wherein the indication is a second indication if the determined distance is greater than the distance threshold.

13. The method of claim 10, further comprising:

comparing the determined distance to a distance threshold; and

injecting a local anesthetic within the treatment area if the determined proximity is less than the distance threshold and the sensed mechanical movement of the muscle was caused by the provided stimulus.