Intraoperative neurophysiological monitoring. Part 2: Neurophysiological background.

Continuous intraoperative monitoring of neurophysiological signals provides a reliable way to determine the functional integrity of the nervous system during the course of neurological, orthopedic, or vascular surgery. To understand the use of electrophysiological recording in the operating room, the basic mechanisms that give rise to the recorded signals are briefly reviewed. Additionally, the equipment necessary for proper signal recording and presentation of the results is described. Finally, a short introduction to anesthesia management and some commonly induced neuroprotective conditions, such as hypothermia and hypotension, are provided, since these are the main factors affecting the signals, thus contributing to the difficulty of correct interpretation of the recordings during the course of an operation.