Multi-Channel Stimulation Threshold Detection Algorithm for use with Neurophysiology Monitoring Systems

Abstract

The present invention relates generally to an algorithm aimed at neurophysiology monitoring, and more particularly to an algorithm capable of quickly finding stimulation thresholds over multiple channels of a neurophysiology monitoring system.

What is claimed is: 
     
         1 . A software application operated on a neurophysiology monitoring system, said software application configured to (a) command delivery of a plurality of stimulation signals at selected current amplitudes, (b) receive and process neuromuscular response data evoked by stimulation at said currents, (c) establish for each selected current amplitude one of a first status and a second status based on the magnitude of the corresponding neuromuscular response, and (d) omit delivery of a stimulation signal of at least one selected current when the status of said at least one current is predictable. 
     
     
         2 . The software application of  claim 1 , wherein at least one of pedicle integrity, nerve proximity, nerve pathology, and spinal cord health is assessed based upon an identified relationship between said current amplitudes and said neuromuscular responses. 
     
     
         3 . The software application of  claim 2 , wherein said identified relationship is the threshold amplitude necessary to evoke a neuromuscular response of a predetermined magnitude. 
     
     
         4 . The software application of  claim 3 , wherein said software application receives neuromuscular response data over at least two channels corresponding to an equal number of sensors deployed to monitor neuromuscular responses of different myotomes. 
     
     
         5 . The software application of  claim 4 , wherein said threshold current is determined for each of the at least two channels. 
     
     
         6 . The software application of  claim 5 , wherein there are 8 channels relaying neuromuscular response data and said threshold current is determined for all 8 channels. 
     
     
         7 . The software application of  claim 3 , wherein said first status applies to a current level which evokes a neuromuscular response one of equal to and greater than said predetermined magnitude and said second status applies to a current level which evokes a neuromuscular response less than said predetermined magnitude. 
     
     
         8 . The software application of  claim 1 , wherein said software application accesses a memory on said neurophysiology monitoring system and retrieves data corresponding to neuromuscular responses associated with previous stimulations. 
     
     
         9 . The software application of  claim 8 , wherein the data retrieved is used by the software application to infer one of said first status and said second status to a given stimulation current and omit delivery of that stimulation current. 
     
     
         10 . The software application of  claim 5 , wherein said software application executes an algorithm to determine said threshold current for each of the at least two channels. 
     
     
         11 . The software application of  claim 10 , wherein said algorithm is based on successive approximation. 
     
     
         12 . The software application of  claim 10 , wherein said algorithm comprises a first step of establishing a bracket within which the threshold current must lie and a second step of bisecting the bracket to a predetermined width. 
     
     
         13 . The software application of  claim 10 , wherein said algorithm comprises a first step of establishing a bracket within which the threshold current must lie and a second step of bisecting the bracket to a predetermined width. 
     
     
         14 . The software application of  claim 10 , wherein said bracketing step is carried out for each channel before the algorithm transitions to said bisection step. 
     
     
         15 . The software application of  claim 10 , wherein said first step of establishing a bracket and said second step of bisecting the bracket are completed on one channel before beginning the steps again on another channel. 
     
     
         16 . The software application of  claim 8 , wherein said software application determines said status of a selected stimulation current by at least one of directing stimulation at said selected current and measuring the magnitude of the neuromuscular response, and inferring the status based on the neuromuscular response data from previous stimulations. 
     
     
         17 . The software application of  claim 16 , wherein said previous neuromuscular response data includes neuromuscular responses measured on one channel in relation to a stimulation current delivered to determine the threshold current on another channel. 
     
     
         18 . The software application of  claim 1 , wherein said first status is assigned without directing a stimulation at said selected current if said selected current is one of equal to and greater than a current level previously assigned said first status on the applicable channel. 
     
     
         19 . The software application of  claim 1 , wherein said second status is assigned without directing a stimulation signal at said selected current if said selected current is less than a current level previously assigned said second status on the applicable channel. 
     
     
         20 . The software application of  claim 3 , wherein said software application is further configured to direct the display of at least one of alpha-numeric, graphic, and color-based indicia to communicate the stimulation threshold results.