Intrinsic Laryngeal Muscle Reinnervation Using the Muscle-Nerve-Muscle Technique

Objectives: This study was performed to investigate the muscle-nerve-muscle reinnervation technique in the larynx, in which a nerve conduit implanted into an innervated muscle conducts axonal sprouting into a denervated muscle while maintaining function of the donor muscle. Methods: In this study, the muscle-nerve-muscle technique was used to direct superior laryngeal nerve axons to reinner-vate intrinsic laryngeal muscles by implanting the recurrent laryngeal nerve stump into the cricothyroid muscle in 8 dogs. In 4 of the dogs, the recurrent laryngeal nerve trunk to the adductor muscles was divided so that all axonal sprouting was directed to the posterior cricoarytenoid muscle. Six-month electromyography data were obtained from 6 of the 8 dogs. Results: All 6 dogs showed evidence of successful reinnervation of the thyroarytenoid or posterior cricoarytenoid mus-cles with action potentials that corresponded to spontaneous respiratory efforts, while the donor cricothyroid muscles re-tained their phasic contraction. These responses were obliterated when the recurrent laryngeal nerve conduit was divided. Histologic examination of the intrinsic laryngeal muscles demonstrated successful reinnervation. Conclusions: The results confirm that intrinsic laryngeal muscles may be successfully reinnervated by the superior laryn-geal nerve with the muscle-nerve-muscle technique, without sacrifice of function of the cricothyroid muscle. This metho