The inferior non recurrent laryngeal nerve: A major surgical risk during thyroidectomy

It is now widely established that systematic intraoperative location and di ligent dissection of the recurrent inferior laryngeal nerve during thyroide ctomy are the keystones to assure its anatomic and functional preservation. The possibility of abnormal routes, like a non-recurrent cervical course o f the inferior laryngeal nerve is an additional major argument for its syst ematic identification to avoid surgical damage. In 2517 cervicotomies perfo rmed between 1992 and 1997 for at least right thyroid lobe excision or para thyroid glands exploration, 20 cases of non recurrent laryngeal nerve were identified (0.79%). The embryological nature of such a nervous anatomical variation results ori ginally from a vascular disorder, named arteria lusoria in which the fourth right aortic arch is abnormally absorbed, being therefore unable to drag t he right recurrent laryngeal nerve down when the heart descends and the nec k elongates during embryonic development. The surgeon must be aware of the possibility of a non recurrent laryngeal nerve, which arises directly from the cervical vagus and therefore represents a severe potential pitfall duri ng thyroidectomy. Given the absence of reliable clinical symptoms and signs or investigations indicating preoperatively the possibility of a non recur rent nerve, guidelines are given to prevent intraoperatively this major sur gical risk.