Intraoperative neurophysiological evaluation of central motor conduction time during an untethering surgery: a case report

Tethered cord syndrome is a congenital disease associated with abnormal stretching of the spinal cord and lumbosacral roots caused by a tight terminal filum. Untethering surgery is performed to minimize or prevent ongoing neurological deficits in the lower limbs, bladder, and bowel functions. As untethering surgery itself carries the risk of inducing additional neural injuries, intra-operative neurophysiological monitoring including electromyography, motor evoked potential (MEP), somatosensory evoked potential, and bulbocavernosus reflex is essential for improving functional outcomes after surgery. However, as MEP reflects the integrity of both the central and peripheral nervous systems, monitoring it alone is insufficient to differentiate between the neural damages of spinal cord and nerve roots. Herein, we report the first case of a child in whom both central motor conduction time and MEP were measured during untethering surgery to differentiate the location of neural injuries between the spinal cord and lumbosacral roots.