A system (10) for performing neurophysiologic assessments during surgery comprises a stimulator (21) to deliver an electrical stimulation signal to a peripheral nerve of a patient, the peripheral nerve exiting the spinal cord inferior to a surgical target site at the patient's spine, at least one sensor (32) to detect electrical action potential from nervous tissue situated superior to the surgical target site and a control unit (12) in communication with the stimulator (21) and the sensor (32). The control unit directs transmission of the stimulation signal, receives electrical action potential data from the sensor, assesses spinal cord health by identifying a relationship between the stimulation signal and the action potential and communicates the relationship to a user.
