Gurleyik Journal of Medical Case Reports 2011, 5:266 http://www.jmedicalcasereports.com/content/5/1/266 diagnosis of toxic multi-nodular goiter. Thyroid hyper- function was normalized with anti-thyroid medication. Our patient was treated with a total thyroidectomy. The weight of the fresh thyroid specimen was 404 g. The inferior thyroid arteries were identified, isolated, and a loop of silk suture was placed around the artery for traction. His ILN was identified below the artery and fully isolated on the left side after freeing and medially mobilizing the thyroid gland. His right ILN was not found at the usual position. An exploration was made for his right ILN at the anticipated crossing point of the nerve and the artery. His right RLN was found not to follow the usual course of the nerve in the tracheaesophageal groove. The dis- section was advanced in an upward direction through the Berry ligament. A non-recurrent laryngeal nerve was identified and exposed near the Berry ligament. The non-recurrent nerve had a course parallel to that of his inferior thyroid artery. The nerve had extra-laryngeal terminal division, as anterior and posterior branches (Figure 1). The laryngeal entry point of the non-recur- rent nerve was the same as the RLN. The two branches entered the larynx separately. After isolation of his left inferior thyroid artery, his left RLN was explored at the anticipated neurovascular crossing point. The main trunk of his left RLN was first identified caudal to the artery. His left RLN was Page 2 of 4 dissected in an upward direction to the laryngeal entry point, for full exposure of the nerve. During surgical dis- section, the left RLN was found to have extra-laryngeal branching at the neurovascular crossing point where the nerve medially passes the inferior thyroid artery. Ante- rior and posterior branches of his left RLN entered the larynx separately. During routine exploration, we inci- dentally found an anastomotic nerve branch with a hori- zontal course on the posterior branch of the left RLN before laryngeal entry (Figures 2 and Figure 3). Discussion The safety of thyroid operations mainly depends on the surgical anatomy of the ILN. The nerve has many varia- tions on its cervical course and full knowledge of RLN anatomy, including all variations, is obligatory for a thyroid surgeon. Variations of the ILN, such as rare non-recurrent ILN, threaten the safety of thyroid opera- tions [5-7]. SILAB is another rare anatomic variation [6,8]. On the other hand, extra-laryngeal terminal divi- sion of RLN is a common variation macroscopically Figure 1 Right non-recurrent ILN with extra-laryngeal bifurcation (magnified and edited operative photograph). Figure 2 Left RLN bifurcated at artery and nerve crossing point. A horizontal nerve anastomosis on the posterior branch of the RLN known as SILAB (magnified and edited operative photograph).