Intraoperative neurophysiologic monitoring during spinal surgery.

Intraoperative neurophysiologic monitoring (IONM) is a battery of neurophysiologic tests used to assess the functional integrity of the spinal cord, nerve roots, and other peripheral nervous system structures (eg, brachial plexus) during spinal surgery. The underlying principle of IONM is to identify emerging insult to nervous system structures, pathways, and/or related vascular supply and to provide feedback regarding correlative changes in neural function before development of irreversible neural injury. IONM data provide an opportunity for intervention to prevent or minimize postoperative neurologic deficit. Current multimodality monitoring techniques permit intraoperative assessment of the functional integrity of afferent dorsal sensory spinal cord tracts, efferent ventral spinal cord motor tracts, and nerve roots. Combined use of these techniques is useful during complex spinal surgery because these monitoring modalities provide important complementary information to the surgery team.