Recovery of laryngeal sensation after superior laryngeal nerve anastomosis

Objectives/Hypothesis: Reliable motor reinnervation has been show in multiple laryngeal transplant studies; however, sensory reinnervation of the larynx after nerve anastomosis has yet to be demonstrated. The role of sensory nerve anastomosis in the transplanted larynx in unknown, but is thought to be necessary to provide airway protection. A canine model was developed to examine the possibility of reformation of sensory pathways in the larynx after nerve section and anastomosis. Study Design: Randomized controlled experiment. Methods: Ten canines were randomly assigned to two groups. Hydrochloric acid-induced laryngospasm was demonstrated in every dog. All dogs then had their necks explored, and the internal branch of the superior laryngeal nerve was identified and transected bilaterally. Following nerve section all dogs mere retested for an acid-induced laryngospasm reflex. The control group had their wounds closed and were then awakened from anesthesia. The study group underwent microscopic anastomosis of their sensory nerves, Following a 6-month period the two groups of dogs were compared for the presence of the laryngospasm reflex, Results: No dog in the control group had a response to the acid. All dogs in the study group had some response to the acid, although none of them had return of true laryngospasm, Conclusion: We concluded that sensory reinnervation does occur after nerve anastomosis, but the recovery of sensation may be incomplete or altered.