System and methods for improving diagnostic evoked potential studies for functional assessments of nerves and nerve pathways
Systems and methods for enhancing diagnostic evoked potential recordings of a nerve or nerve pathway of interest. A grid array of stimulating electrodes are placed on, over, or through skin in a location beneath which a nerve or nerve pathway is suspected to lie. A stimulator controls the grid array, where each electrode is independently controllable as active or inactive, as a cathode or anode, etc. A plurality of recording electrodes may record Somato-Sensory Evoked Potentials (SSEPs) and/or Transcranial Electrical Motor Evoked Potentials (TCeMEP) in response to activation of the stimulating electrodes. A processor controls stimulating the stimulating electrodes, and receives responses from the recording electrodes, in a general search mode and a focused search mode in order to use a minimum stimulation intensity at which a maximum response amplitude is detected to continually stimulate the nerve or the nerve pathway.
1 . A system comprising:
a plurality of stimulating electrodes arranged in a grid array configured to be placed on, over, or through skin over an area of a nerve or nerve pathway;
a stimulator configured to control the grid array;
a plurality of recording electrodes; and
one or more processors configured to:
execute a general search mode comprising:
instructing the stimulator to systematically test a plurality of stimulation schemes until a first evoked potential response is detected by the plurality of recording electrodes having a maximum response amplitude, wherein:
each of the plurality of stimulation schemes includes activating and assigning positions and polarity of one or more of the plurality of stimulating electrodes, and
instructing the stimulator to systematically test the plurality of stimulation schemes in the general search mode comprises instructing the stimulator to ramp stimulation intensity during testing each of the plurality of stimulation schemes until at least one of: a maximum stimulation intensity value is reached, or the maximum response amplitude is detected;
execute a focused search mode after executing the general search mode, the focused search mode comprising:
utilizing information from the general search mode, instructing the stimulator to systematically test the plurality of stimulation schemes until a second evoked potential response is detected by the plurality of recording electrodes having the maximum response amplitude and a minimum stimulation intensity, wherein:
instructing the stimulator to systematically test the plurality of stimulation schemes in the focused search mode comprises instructing the stimulator to ramp stimulation intensity during testing each of the plurality of stimulation schemes until the maximum response amplitude is detected;
for each stimulation scheme of the plurality of stimulation schemes, recording a respective stimulation intensity for the stimulation scheme at which the maximum response amplitude is detected;
comparing the respective stimulation intensities of the plurality of stimulation schemes at which the maximum response amplitudes was detected; and
selecting the minimum stimulation intensity at which the maximum response amplitude was detected; and
use the minimum stimulation intensity at which the maximum response amplitude was detected to further stimulate the nerve or nerve pathway.
2 . The system of claim 1 , wherein:
each of the plurality of stimulating electrodes is independently assignable to be active or inactive,
each of the plurality of stimulating electrodes is independently assignable to be active as an anode or a cathode, and
the stimulator is configured to independently assign stimulation parameters to each of the plurality of stimulating electrodes.
3 . The system of claim 1 , wherein the maximum response amplitude of the first evoked potential response does not increase in amplitude upon an increase in stimulation intensity.
4 . The system of claim 1 , wherein, during the general search mode, a stimulation scheme of the plurality of stimulation schemes at which the maximum response amplitude is detected comprises a positive stimulation scheme, and wherein information from the positive stimulation scheme is used to instruct the stimulator to systematically test the plurality of stimulation schemes during the focused search mode.
5 . The system of claim 1 , wherein the general search mode further comprises, after the first evoked potential response is detected, executing another stimulation scheme from among the plurality of stimulation schemes.
6 . The system of claim 1 , wherein each stimulating electrode of the plurality of stimulating electrodes is at least one of: percutaneous or transcutaneous.
7 . The system of claim 1 , wherein at least one of the plurality of stimulating electrodes of the grid array comprises an atraumatic tip.
8 . The system of claim 1 , wherein both the grid array and the plurality of recording electrodes are configured to be placed on a first appendage.
9 . The system of claim 1 , wherein the grid array comprises a plurality of smaller grid arrays each configured to stimulate multiple points along a course of the nerve or nerve pathway.
10 . The system of claim 1 , wherein the one or more processors are further configured to:
in response to receiving an input from a safety button capable of being pressed by an awake subject, immediately stopping all stimulation.
11 . The system of claim 1 , wherein the one or more processors are further configured to:
in response to receiving an input from a user control, modifying at least one of the general search mode or the focused search mode by limiting a total number of the plurality of stimulation schemes used during the at least one of the general search mode or the focused search mode.
12 . The system of claim 1 , further comprising semi-automatically executing the general search mode and the focused search mode, wherein at least one of the general search mode or the focused search mode is interruptible by a user.
13 . The system of claim 1 , wherein the plurality of recording electrodes is configured to record at least one of: Somato-Sensory Evoked Potentials (SSEPs), Transcranial Electrical Motor Evoked Potentials (TCeMEP), Compound Muscle Action Potentials (CMAPs), Sensory Nerve Action Potentials (SNAPs), or Mixed Nerve Action Potentials (MNAPs), providing a user with a functional assessment of peripheral mixed nerve function, peripheral motor nerve function, peripheral sensory nerve function, and/or the nerve or nerve pathway during a procedure in which the nerve or nerve pathway is known to be at risk of damage.
14 . A computer-implemented method comprising:
by one or more processors executing program instructions:
communicating with a stimulator configured to control a grid array of a plurality of stimulating electrodes;
executing a general search mode comprising:
instructing the stimulator to systematically test a plurality of stimulation schemes until a first evoked potential response is detected by a plurality of recording electrodes having a maximum response amplitude, wherein:
each of the plurality of stimulation schemes includes activating and assigning positions and polarity of the plurality of stimulating electrodes, and
instructing the stimulator to systematically test the plurality of stimulation schemes in the general search mode comprises instructing the stimulator to ramp stimulation intensity during testing each of the plurality of stimulation schemes until at least one of: a maximum stimulation intensity value is reached or the maximum response amplitude is detected;
executing a focused search mode after executing the general search mode, the focused search mode comprising:
utilizing information from the general search mode, instructing the stimulator to systematically test the plurality of stimulation schemes until a second evoked potential response is detected by the plurality of recording electrodes having the maximum response amplitude and a minimum stimulation intensity, wherein:
instructing the stimulator to systematically test the plurality of stimulation schemes in the focused search mode comprises instructing the stimulator to ramp stimulation intensity during testing each of the plurality of stimulation schemes until the maximum response amplitude is detected;
for each stimulation scheme of the plurality of stimulation schemes, recording a respective stimulation intensity for the stimulation scheme at which the maximum response amplitude is detected;
comparing the respective stimulation intensities of the plurality of stimulation schemes at which the maximum response amplitude was detected; and
selecting the minimum stimulation intensity at which the maximum response amplitude was detected; and
using the minimum stimulation intensity at which the maximum response amplitude was detected to further stimulate a nerve or nerve pathway.
15 . The computer-implemented method of claim 14 , wherein:
each of the plurality of stimulating electrodes is independently assignable to be active or inactive,
each of the plurality of stimulating electrodes is independently assignable to be active as an anode or a cathode, and
the stimulator is configured to independently assign stimulation parameters to each of the plurality of stimulating electrodes.
16 . The computer-implemented method of claim 14 , wherein the maximum response amplitude of the first evoked potential response does not increase in amplitude upon an increase in stimulation intensity.
17 . The computer-implemented method of claim 14 , wherein, during the general search mode, a stimulation scheme of the plurality of stimulation schemes at which the maximum response amplitude is detected comprises a positive stimulation scheme, and wherein information from the positive stimulation scheme is used to instruct the stimulator to systematically test the plurality of stimulation schemes during the focused search mode.
18 . The computer-implemented method of claim 14 , wherein the general search mode further comprises, after the first evoked potential response is detected, executing another stimulation scheme from among the plurality of stimulation schemes.
19 . The computer-implemented method of claim 14 , wherein both the grid array and the plurality of recording electrodes are configured to be placed on a first appendage.
20 . The computer-implemented method of claim 14 , further comprising semi-automatically executing the general search mode and the focused search mode, wherein at least one of the general search mode or the focused search mode is interruptible by a user.