Use of postoperative neurophysiological testing to help guide management in a case of delayed neurological injury

Bimodal intraoperative neuromonitoring (IONM), combining transcranial motor-evoked potentials (tcMEP) and somatosensory-evoked potentials (SSEP), enables real-time detection and prevention of spinal cord injury during pediatric spinal deformity correction. Although rare, false-positive and false-negative signal alerts have been reported. However, no previously published accounts have described the use of postoperative neurophysiological testing to both identify new-onset neurological injury and guide reintervention. Here, we describe the case of an 18-year-old young man with achondroplasia, thoracolumbar kyphosis, and L2 wedge vertebra who underwent T12-L4 posterior spinal fusion with L2 vertebral column resection. Despite two intraoperative decreases in tcMEP amplitude, corrective measures on both occasions produced a return of IONM signal. Curiously, despite movement of the bilateral lower extremities upon waking, continued observation demonstrated minimal movement of the left lower extremity. Postoperative neurophysiological testing then identified limited muscle group activation below the left quadriceps, prompting operative reintervention. After cage removal and laminectomy lengthening, the patient recovered bilateral lower extremity function. He later returned to surgery for repeat cage placement at L2 via a retroperitoneal exposure, with no noted IONM changes and subsequent neurological improvement.