Transposition of infrahyoid muscles to replace intrinsic laryngeal muscles: technique and long-time observations on...

Insertion of the separate motor branches of the caudal laryngeal nerve of the dog separately and atraumatically into a denervated infrahyoid muscle resulted in reinnervation of that muscle, as indicated by the appearance of electromyographic potentials two months postoperatively. When the nerve branches were used to reinnervate a sufficiently large mass of muscle, which was transposed to replace surgically removed intrinsic laryngeal muscles, nearly normal adduction and abduction of the vocal cord was obtained on the experimental side in some dog if ample time were allowed for maturation of nerve fibers and motor end plates. The minimum time for return of effective function under these circumstances was slightly more than 12 months, and function may improve for up to 36 months. A simplified procedure is described for reconstructing the intrinsic laryngeal muscles following submucosal resection. Electromyography is useful in monitoring the progress of reinnervation of muscle, but it is not a reliable indicator of mechanical function.