Reliabilty of intraoperative recurrent laryngeal nerve monitoring in thyroid surgery

Introduction: The intraoperative monitoring of the recurrent laryngeal nerve (NLR) is increasingly used in throid surgery. What has the surgeon to know about reliability and peculiarity of this method? Patients and Method: Between 11/98 and 3/01 417 patients were operated for thyroid pathology. Vocal cord function was controlled pre- and postoperatively in all cases by laryngoscopy. Intraoperative electromygraphic NLR identification and postoperative vocal cord function were registered prospectively. Results: Intraoperative NLR identification succeeded in 98.9% (776/784 nerves at risk). Minor vocal cord disfunctions were demonstrable for less than 4 weeks in 13 patients (1.6%) associated with edema or hematoma in 11/13cases. Complete unilateral NLR pareses was seen layngoscopically in 16 patients (2%). 1 patient revealed a malignant NLR infiltration. Electromygraphic NLR identification wasn't possible and followed by postoperative NLR palsy in 2 patients. In 11/13 cases with a regular intraoperative monitoring postoperative vocal cord function recovered within 8 weeks. In 2 of 4 NLR pareses persisting at the moment the follow up is longer than 12 months (permanent palsy rate 0.25%). Conclusions: NLR identification during thyroid surgery is improved by intraoperative monitoring. In cases with, difficult thyroid preparation the vagal nerve may be stimulated for indirect proof of NLR integrity.