Tethered cord syndrome is a type of spinal dysraphism with a low-lying conus, which is frequently associated with an intraspinal lipoma, diastematomyelia, or fibrous band. The clinical manifestations include spine abnormalities such as the spina bifida or various neurological symptoms involving lower extremities and sphincters. However, the spinal roots are often injured during the detethering procedures which clinically results in a neurological deficit. The continuity of spinal roots should be monitored during detethering surgery for the tethered spinal cord because neural elements are embedded in lipoma or anomalous tissues. Evoked muscle action potentials indicate only motor function, therefore, it is more appropriate to record somatosensory evoked potentials across the operative field at the same time.

We used a combined technique of tibial nerve somatosensory evoked potential and compound muscle action potentials stimulated in the spinal roots directly for an intraoperative monitoring during the untethering procedure. We reported good results from three patients with tethered cord syndrome who had taken the intraoperative monitoring during the untethering surgery. We suggest that intraoperative monitoring can prevent the unwanted injury to the neural tissue in the level of the tethering during the detethering surgery.