Method and system for monitoring a nerve

• US 9,579,037 B2
• Filed: 07/20/2015
• Issued: 02/28/2017
• Est. Priority Date: 12/08/2008
• Status: Active Grant

• Current Assignee: Medtronic Xomed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Xomed Incorporated (Medtronic Plc)
• Inventors: Brunnett, William C., Hacker, David C., Meyer, John A., McFarlin, Kevin Lee, Murphy, John Murdock, Yamasaki, Dwayne S., Gardi, John N.
• Primary Examiner(s): Stout, Michael C
• Application Number:
  US14/803,623
• Publication Number:
  US 20150320329A1
• Time in Patent Office: 589 Days
• Field of Search: 600/554, 600/546
• US Class Current: 1/1
• CPC Class Codes: A61B 2505/05 Surgical care
• CPC Class Codes: A61B 5/05 Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves impedance plethysmography A61B5/0295; measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/389 Electromyography [EMG]
• CPC Class Codes: A61B 5/4041 Evaluating nerves condition
• CPC Class Codes: A61B 5/4893 Nerves
• CPC Class Codes: A61B 5/6877 Nerve
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: A61B 5/741 using synthesised speech
• CPC Class Codes: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B
• CPC Class Codes: A61N 1/0556 Cuff electrodes
• CPC Class Codes: A61N 1/3605 Implantable neurostimulators for stimulating central or peripheral nerve system

Abstract

A nerve monitoring system facilitates monitoring an integrity of a nerve.

Claims

1. A nerve monitor comprising:

a user interface including at least an audio element to selectively emit an audible alert; and

a controller, including a processing unit to execute instructions, stored in a non-transitory memory, to;

automatically and periodically apply an electrical stimulation signal to the nerve to elicit an evoked potential; and

automatically measure a neurogenic response signal of the evoked potential, including instructions to;

automatically identify potential nerve impairment based on the measured neurogenic response signal including differentiating multiple different types of identified nerve impairment from each other as at least one of;

a tension impairment of the nerve as indicated by an increase in response latency and a decrease in response amplitude;

a compression impairment of the nerve as indicated by a decrease in response amplitude without a substantial change in latency;

a composite impairment of the nerve including at least the tension impairment and the compression impairment; and

an electrocautery impairment of the nerve as indicated by a detected electrocautery event occurring substantially synchronous with at least one of the types of the tension impairment, the compression impairment, and the composite impairment; and

automatically provide the audible alert of the identified potential nerve impairment via the audio element of the user interface.

2. The nerve monitor of claim 1, wherein the measured neurogenic response signal comprises at least one of:

a direct response signal measured at a location of the nerve spaced apart from a location at which the stimulation signal is applied;

an indirect response signal measured at a muscle innervated by the nerve;

a chemical-based neurogenic response signal; and

a smooth muscle-based neurogenic response signal.

3. The nerve monitor of claim 1, wherein the instructions to automatically identify potential nerve impairment include instructions to automatically identify the potential nerve impairment based on differences between the measure neurogenic response signal and a baseline neurogenic response pattern and wherein the instructions are to implement the automatically provide the audible alert when the differences exceed a predetermined limit.

4. The nerve monitor of claim 3 wherein, the instructions to automatically measure a neurogenic response comprise instructions to at least one of:

identify a decrease in the amplitude of the measured response signal relative to an amplitude parameter of the baseline response pattern;

identify an increase in the latency of the measured response signal relative to a latency parameter of the baseline response pattern; and

to identify a decrease in an energy of the measured response signal relative to an energy parameter of the baseline response pattern.

5. The nerve monitor of claim 3 wherein, the instructions to automatically measure a neurogenic response comprise instructions to at least one of:

identify an increase or decrease in a nerve conduction velocity of the measured response signal relative to a nerve conduction velocity parameter of the baseline response pattern;

identify, relative to a nerve refractory recovery parameter of the baseline response pattern, a change in at least one of a double response time, an amplitude, or a latency of a nerve refractory recovery waveform produced in response to a plurality of the stimulation signals; and

identify, relative to a nerve refractory recovery parameter of the baseline response pattern, a change in at least one of a neurogenic response morphology waveform or a neurogenic response synchrony pattern produced in response to a plurality of the stimulation signals.

6. The nerve monitor of claim 3 wherein, the instructions to automatically measure a neurogenic response comprise instructions to at least one of:

identify an increase or decrease a nerve stimulation of the measured response signal relative to a nerve stimulation parameter of the baseline response pattern; and

identify an increase or decrease a nerve stimulation saturation of the measured response signal relative to a nerve stimulation saturation parameter of the baseline response pattern.

7. The nerve monitor of claim 3, wherein the instructions to automatically measure a neurogenic response includes instructions to determine the baseline response pattern as an identification of an initial neurogenic status of the nerve according to multiple evoked responses via at least one of:

a statistical mean of the multiple evoked responses; and

a variance measurement of the multiple evoked responses.

8. The nerve monitor of claim 3, wherein the instructions to automatically measure a neurogenic response includes instructions to determine the baseline response pattern as an identification of an initial neurogenic status of the nerve via sorting a variability of the multiple evoked responses according to a Poisson distribution.

9. The nerve monitor of claim 3, wherein the instructions to automatically measure a neurogenic response includes instructions to determine the baseline response pattern as an identification of an initial neurogenic status of the nerve according to multiple evoked responses via at least one of:

an exclusion of a portion of the multiple evoked responses based on a variability of the multiple evoked responses;

an exclusion of at least one of a maximum value or a minimum value of the multiple evoked responses; and

an exclusion of non-evoked responses.

10. The nerve monitor of claim 3, wherein the instructions to automatically measure a neurogenic response includes instructions to determine the baseline response pattern as an identification of an initial neurogenic status of the nerve according to multiple evoked responses via at least one of:

a rate of change of at least one parameter of the multiple evoked responses; and

a rolling window of multiple evoked responses.

11. The nerve monitor of claim 3 wherein the nerve monitor includes a user interface configured to communicate the audible alarm and wherein the notify function includes at least one of:

a graduated type of notification in which a volume of the alarm is in proportion to a degree of deviation of the measured response from the baseline response pattern; and

a tone type of notification in which a type of tone corresponds to a degree of deviation of the measured response from the baseline response pattern.

12. The nerve monitor of claim 1 wherein the instructions to automatically provide the audible alert includes instructions to audibly announce a different verbal expression for each different type of the multiple different types of nerve impairment.

13. The nerve monitor of claim 1, and further comprising:

a stimulation electrode removably securable to the nerve to maintain a continuous electrical pathway from the monitor to the nerve throughout the surgical procedure, wherein the nerve monitor comprises;

a nerve stimulator connectable to the stimulation electrode to deliver the automatically and periodically applied electrical stimulation signal.

14. The nerve monitor of claim 1, and further comprising:

a response electrode removably securable relative to at least one of the nerve or an innervated muscle to maintain a continuous electrical pathway from the respective nerve or the innervated muscle to the response module throughout the surgical procedure, wherein the nerve monitor comprises;

a response measurement unit connectable to the response electrode to perform the automatic measurement of the neurogenic response signal.

15. The nerve monitor of claim 1 wherein the instructions to automatically provide the audible alert includes instructions to:

audibly announce a different verbal expression, based on the identified type of nerve impairment, for each multiple different type of nerve impairment.