A clinical study of the nonrecurrent inferior laryngeal nerve in seven patients

Abstract

Nonrecurrent inferior laryngeal nerves (NRILNs) are generally discovered during thyroid or parathyroid gland surgery. If the presence of the NRILN is unknown, nerve injury can easily occur during surgery. Here we report seven cases of NRILN, describe how to identify a NRILN, and discuss whether preoperative or postoperative examination is necessary. Between October 1998 and March 2000, we performed cervicotomy in 1889 patients for thyroid and parathyroid disease and identified a NRILN in 7 of them (0.37%). A NRILN was found in 7 of 903 patients (0.78%) on the right side but in none of 855 patients on the left. The NRILN branched off the vagus nerve at the level of the upper or middle third of the thyroid in 5 patients, and in the other 2 patients branched off the vagus nerve at the level of the lower third of the thyroid. We had not predicted the presence of NRILN before surgery in any of these 7 NRILN patients. Clinically, three patients with NRILN had mild dysphagia and the sensation of a foreign body in the throat. Three patients had abnormal chest X-ray findings showing a linear aortic arch shadow, a sign regarded as evidence of arteria lusoria. Three patients underwent MR angiography, and an aberrant right subclavicular artery was identified. Surgery was performed safely, and no postoperative vocal cord palsy occurred in any of the seven NRILN patients. It is to some extent possible to predict the presence or absence of NRILN by routine diagnostic examinations before surgery for thyroid and parathyroid disease. We emphasize that digital subtraction angiography, MR angiography, or barium esophagography is not necessary for all patients before surgery, since NRILN is a relatively rare anomaly, and such examinations are either invasive or not cost-effective. When a NRILN has been identified during surgery, there is no need to examine for the presence of a vascular anomaly: Its presence is a matter of course. Surgery must be performed however, with knowledge of the possibility of a NRILN.