Clinical neurophysiology encompasses a variety of diagnostic tests including EEG, nerve conduction studies, electromyography, evoked potentials and polysomnography. This chapter describes the tests that are most widely used for monitoring during neuroanaesthesia and neurocritical care, specifically, EEG, somatosensory evoked potentials (SSEPs), brainstem auditory evoked potentials, motor evoked potentials (MEPs) and electromyography (EMG). The main indications for EEG are in the diagnosis and management of epilepsy, sleep studies and neuromonitoring. Evoked potentials are the electrical response from the nervous system to an external stimulus. There are two types of EPs: sensory and motor. SSEPs monitor the integrity of sensory pathways, including peripheral nerves, and MEPs the motor pathways. Electromyography is a technique used to evaluate the electrical activity in muscle fibres. Two types of EMG monitoring commonly used include: recording spontaneous electrical activity and recording responses generated by stimulation of motor nerves.

This chapter presents a case study of a 56-year-old male, American Society of Anesthesiologists Class III, scheduled to undergo T9-T12 laminectomy and microsurgical correction of a T10-T12 dural ateriovenous fistula. Central nervous system (CNS) function was monitored using somatosensory evoked potentials (SSEP), electromyography (EMG) and transcranial motor evoked potentials (MEP). The neurophysiologic monitors used in this case were monitors of CNS function, and can be described as follows: sensory evoked potentials (SEPs); motor evoked potentials; electromyography; and intraoperative changes. Sensory evoked potentials (SEPs) are measured electrophysiologic responses to somatosensory, visual, or auditory stimulation. Electromyography consists of monitoring muscle activity in response to either spontaneous or active nerve stimulation. In the immediate postoperative period a brief neurologic exam completed by the anesthetic team should be documented in the anesthetic record. In these ways morbidity and mortality in complex spine surgery using neurophysiologic monitoring can be reduced.