Intraoperative laryngeal nerve monitoring during thyroidectomy.

OBJECTIVE To determine whether nerve integrity monitor testing during thyroidectomy predicts recurrent laryngeal nerve (RLN) function after surgery. DESIGN Prospective cohort outcomes study PATIENTS The study included 210 consecutive patients with thyroid abnormalities who underwent thyroidectomy. METHODS All patients were intraoperatively monitored with a nerve integrity monitoring system (Xomed NIM II; Medtronic Inc, Fridley, Minnesota), and their vocal cord function was assessed with fiberoptic laryngoscopy before and after surgery. Normal and impaired vocal cord function were compared using an independent t test with respect to postoperative vocal cord mobility, length of the RLN dissection, and the minimum stimulus needed to generate a response at the completion of surgery. RESULTS There was a statistically significant difference between the stimulus in milliamperes required to stimulate normal vs abnormal functioning nerves at the completion of the procedure at the cricoarytenoid joint (P = .02) and at the distal end of the RLN dissection (P < .01). A greater length of dissected nerve was associated with normal vocal cord function; however, it was not statistically significant (P = .07). CONCLUSION These data suggest that an RLN that responds at lower-intensity stimulation (</=0.5 mA) at the end of thyroid surgery is associated with normal vocal cord mobility.