Extralaryngeal division of the recurrent laryngeal nerve. Report on 400 patients and the 721 nerves measured.

Seven hundred twenty-one recurrent laryngeal nerves were visualized in 400 patients having thyroid or parathyroid surgery. Four hundred twenty-one nerves (58 percent) bifurcated or trifurcated more than 0.5 cm from the cricoid cartilage. Ninety-seven patients had bilateral bifurcations, and 10 patients had trifurcations. Six patients had direct laryngeal nerves, all on the right side. One patient had a direct laryngeal and a recurrent laryngeal nerve simultaneously, and one patient had a bifurcated recurrent laryngeal nerve with an accessory vagus nerve joining it 13.5 cm from the cricoid cartilage. Damage to any of the filaments of the recurrent laryngeal nerve to the cricothyroid musculature or to or from a variant direct laryngeal nerve or variant vagus nerve connection can cause vocal cord paralysis. Damage to any branches of the recurrent laryngeal nerve to the esophagus can cause dysphagia. Therefore, if possible, all branches of the recurrent laryngeal nerve, no matter how small, should be preserved.