Intraoperative Recurrent Laryngeal Nerve Monitoring May Decrease Complications in Anterior Cervical Spine Surgery

Recurrent Laryngeal Nerve (RLN) dysfunction is a debilitating complication of anterior cervical spinal procedures. Routine monitoring of RLN function for anterior cervical procedures has not been analyzed in the literature. We prospectively monitored RLN function intraoperatively in twenty consecutive anterior cervical spine surgeries to determine when the RLN evidenced manipulation. 4 corpectomies, 12 anterior cervical discectomy with fusion, 2 anterior cervical discectomies and 2 anterior foraminotomies were performed. Vocal cord function was assessed pre and postoperatively via strobe endoscopy. Exposure was right sided in eight procedures and 12 were left. Levels operated on ranged from C–3 to T–1. A custom endotracheal monitoring tube was used, allowing RLN monitoring throughout the procedure. Episodes of stimulation were recorded, along with the antecedent surgical activity. There were no episodes of permanent RLN dysfunction during the study. Correlation was noted between depth of anesthesia and ability to record RLN tracings reliably. Surgical activity most associated with RLN activity was blunt dissection in the fascial plane between the sternocleidomastoid and strap muscles of the neck. Spontaneous RLN firing could be noted with retraction, and silenced by decreasing the amount of retraction. Left sided approaches were associated with decreased RLN activity than right. No difference was noted in activity versus level operated. The incidence of RLN dysfunction after cervical spine surgery is sufficiently rare that a larger patient sampling is currently underway. Available data suggest that intraoperative monitoring assists the surgeon in preventing RLN trauma by providing instant feedback when potentially injurious events occur.