Patent ID: 8634904

Claim:
A method of establishing an operative corridor for spinal surgery, comprising: mounting a plurality of sensors proximate to selected leg muscles; activating a nerve monitoring system that outputs stimulation signals to at least one stimulation electrode on a dilator and that, in response to signals from the sensors, displays neuromuscular response information which is indicative of nerve proximity to the at least one stimulation electrode, the nerve monitoring system directing the application of the stimulation signals to the at least one stimulation electrode according to an algorithm configured to identify a stimulation threshold that evokes a predetermined neuromuscular response, the algorithm including a detection sequence and a monitoring sequence, wherein the detection sequence adjusts the amplitude of the stimulation signals until an initial bracket that contains the stimulation threshold is determined, the initial bracket including an initial upper boundary at which the predetermined neuromuscular response is evoked and an initial lower boundary at which the predetermined neuromuscular response is not evoked, the detection sequence further adjusting the amplitude of the stimulation signals to repeatedly bisect the initial bracket until a final bracket that contains the stimulation threshold is determined, the final bracket including a final upper boundary at which the predetermined neuromuscular response is evoked and a final lower boundary at which the predetermined neuromuscular response is not evoked, the final upper boundary and final lower boundary being separated by a predetermined width and the stimulation threshold being selected from the final bracket, and wherein the monitoring sequence repeatedly adjusts the amplitude of the stimulation signals between the final lower boundary and the final upper boundary to detect changes to the stimulation threshold; advancing the dilator through body tissue having neural structures along a path to a targeted intervertebral disc of a spine; while the dilator is positioned along the path to the spinal target site, viewing the neuromuscular response information indicative of nerve proximity on a display device of the nerve monitoring system; advancing a plurality of sequential dilator cannulas along the selected path toward the targeted intervertebral disc of the spine; advancing a working corridor instrument over an outermost dilator cannula of the plurality of sequential dilator cannulas toward the targeted intervertebral disc of the spine; and establishing an operative corridor to the targeted intervertebral disc of the spine using the working corridor instrument.