24. IOM in tethered spine surgery

Abstract

Tethered cord syndrome (TCS) is a disorder in which the distal spinal cord is tethered caudally to an immovable boney structure. This results in dysfunction of the lower spinal cord and cauda equina, manifest as lower extremity weakness, sensory loss, bowel and bladder dysfunction and occasionally musculoskeletal deformities. Surgery for TCS involves releasing the tethering structure and correcting the musculoskeletal abnormalities. Because the neural elements of the cauda equina are in close proximity, there is potential for damage to these structures during surgery. Neurophysiologic intraoperative monitoring (NIOM) can help prevent injury to these structures. NIOM for TCS surgery can include monitoring free running and stimulated electromyography (EMG), anal sphincter EMG, tibial nerve somatosensory evoked potentials (SEP), motor evoked potentials, bulbocavernosus reflex and pudendal nerve SEP. These monitoring modalities will be discussed.