Successful monitoring of neurogenic mixed evoked potentials elicited by anterior spinal cord stimulation through thoracoscopy during spine surgery

Study Design. Neurogenic mixed evoked potentials were recorded after thorac oscopic spinal cord stimulation inpatients undergoing video-assisted spine surgery. Objective. To demonstrate the feasibility and value of thoracoscopic spinal cord monitoring. Summary of Background Data. Video-assisted thoracic surgery recently has be en proposed as a new technique for thoracic spine surgery. It can be used f or anterior spinal release of patients with severe spinal deformities and f or thoracic hernia removal. Methods. Five patients undergoing video-assisted thoracic surgery for spina l fusion were studied. Neurogenic mixed evoked potentials were elicited by electrodes seated into intervertebral discs through thoracoscopy and record ed from peripheral nerves of the lower limbs. Moreover, the study included the case of a patient with a thoracic hernia who underwent video-assisted t horacic surgery with combined thoracoscopic neurogenic mixed evoked potenti al and standard somatosensory evoked potential monitoring. Results. Neurogenic mixed evoked potentials were recorded consistently afte r spinal cord stimulation in all patients. For the patient with a thoracic hernia, neurogenic mixed evoked potentials suddenly disappeared, whereas so matosensory evoked potentials were not significantly modified, leading to s urgery interruption. Neurogenic mixed evoked potentials progressively reapp eared after a 30-minute delay. Postoperation examination revealed a Brown-S equard's syndrome with incomplete right motor deficit. Conclusions. Neurogenic mixed evoked potentials evoked by anterior stimulat ion through thoracoscopy are of interest for spinal cord monitoring when po sterior electrical stimulation is impossible, and they provide reliable inf ormation regarding spinal motor pathways.