Coexisting right nonrecurrent and right recurrent inferior laryngeal nerves: a rare and controversial entity

Variations in the course of the recurrent laryngeal nerve (RLN) can occur, including the development of a nonrecurrent inferior laryngeal nerve (NRILN). Rarely, both a right RLN and a right NRILN have been reported in the same patient, merging before they enter the larynx. A case is presented, including images, and the literature concerning this rare anatomical finding is reviewed, including studies suggesting alternative explanations for these cases. Fourteen previously reported cases of coexisting RLN and NRILN were identified, all involving the right side. Some cases were associated with an anomalous origin of the right subclavian artery and some were not. The alternative explanations that a communicating branch of the sympathetic nerve, which joins the RLN, is mistaken for an NRILN or that a collateral branch from an NRILN is mistaken for an RLN in these cases are also considered. Surgeons must be aware of these unusual variations to minimize nerve injury during neck surgery.