The "false" nonrecurrent inferior laryngeal nerve

BACKGROUND: Communicating branches between the cervical sympathetic system and the inferior laryngeal nerve (ILN) have been described. They usually originate from the middle cervical sympathetic ganglion (MCSG). These branches (sympathetic-inferior laryngeal anastomotic branch [SILAB]), usually thin, sometimes have the same diameter as the ILN. In this study we prospectively evaluated the frequency of this condition and its implications during surgical neck exploration. METHODS: From November 1998 to October 1999, 791 patients underwent surgical neck exploration, and 1253 ILNs were dissected: 656 on the right side (52.3%) and 597 on the left side (47.7%). RESULTS: On the right side, a nonrecurrent ILN was found in 3 cases (0.46%), and a large SILAB was found in 10 cases (1.5%). The SILAB originated from the superior cervical sympathetic ganglion in 2 cases and directly from the sympathetic trunk above the MCSG in 8 cases. No anomalous branch was found on the left side. CONCLUSIONS: The SILAB may originate not only from the MCSG but also from the superior cervical sympathetic ganglion or directly from the sympathetic trunk. When the SILAB is as large as the ILN, it could be mistaken for a nonrecurrent ILN. The awareness of this anatomic condition during neck dissection may help to avoid injuries of the genuine ILN running in the usual pathway.