MICHAEL E. JONES, MD; DONALD J. WEISZ, PHD; MARK L. URKEN, MD

NEW YORK, NEW YORK

Anesthesia or hypesthesia in the laryngopharynx following stroke or injury to the internal superior laryngeal nerve (ISLN) can result in dysphagia, aspiration, pneumonia, and/or death. Attempts to reinnervate an anesthetic laryngopharynx have not established accurate cortical representation of sensation or reconstituted the laryngeal reflexes. The purpose of our study was to 1) determine if there is a consistent branching pattern of the ISLN; 2) map, with the use of electrophysiological testing, the mucosal receptive fields of such conserved branches; and 3) identify branches that might serve as both donor and recipient nerves of a restorative nerve graft. Twelve canine larynges and 24 ISLNs were examined. The ISLN showed a consistent branching pattern in all 24 nerves. Three branches of the ISLN (superior, middle, and descending) were consistently found approximately 1 to 2 cm prior to their entrance into the larynx. The mucosal receptive fields of these branches were mapped in 5 dogs (10 nerves). The superior branch innervated the area from the tip of the pharyngeal epiglottis to the false vocal fold. The middle branch innervated the mid-pharyngeal epiglottis, false vocal fold, and arytenoid, while the descending branch innervated the arytenoid. In conclusion, we have found a consistent branching pattern of the ISLN. Moreover, each branch was found to consistently innervate a specific area of the larynx with redundancy between branches and minimal interanimal variability.