Nonrecurrent inferior laryngeal nerves and anatomical findings during thyroid surgery: report of three cases

A nonrecurrent inferior laryngeal nerve (NRILN) is found more frequently on the right side than on the left, and it is closely associated with an aberrant right subclavian artery. The presence of the aberrant right subclavian artery on preoperative computed tomography (CT) scan suggests NRILN; however, different types of branching locations and pathways exist. Here, we report three NRILN cases with different pathways where the vagus nerve arises more medial than usual and a review of the literature. Case 1: A 30-year-old Japanese female presented with papillary thyroid carcinoma. Preoperative CT scan revealed an aberrant right subclavian artery, and an operation was performed under suspicion of NRILN. During the operation, the vagus nerve was found to arise more medially than usual and two NRILNs originated from it at the level of the cricoid cartilage and at a more caudal position; the two NRILNs were preserved. Case 2: A 33-year-old Japanese female with a thyroid nodule of increased size underwent surgery. Preoperative CT scan revealed an aberrant right subclavian artery, which suggested NRILN. During the operation, the vagus nerve was identified to run more medially than usual and NRILN was found to originate at the level of the cricoid cartilage; NRILN was preserved. Case 3: A 78-year-old Japanese female underwent an operation with a diagnosis of papillary thyroid carcinoma. Preoperative CT scan showed an aberrant right subclavian artery. During the operation, NRILN was found to originate from the vagus nerve at the level of the lower pole of the thyroid gland, and the vagus nerve ran medial to the common carotid artery at the caudal level.