Effects of Nerve-Muscle Pedicle on Immobile Rat Vocal Folds in the Presence of Partial Innervation

Abstract

We investigated whether implantation of an ansa cervicalis nerve (ACN)-muscle pedicle into the thyroarytenoid (TA) muscle is efficacious in the presence of partial recurrent laryngeal nerve (RLN) innervation. We studied a total of 36 rats. Twelve of the rats served as positive and negative control animals. In the remaining 24 rats, the left RLN was transected, a 1-mm piece of nerve was removed, and the stumps were abutted in silicone tubes (STs), inducing partial RLN regeneration. Twelve of the ST-treated rats underwent this procedure alone, and the other 12 rats had a nerve-muscle pedicle (NMP) implanted into the left TA muscle 5 weeks after ST treatment. At 15 weeks, reinnervation was assessed by histologic evaluation of the TA muscle and by electromyography with stimulation of the RLNs and ACNs. The muscle area, the number of nerve terminals, the number of acetylcholine receptors, and the ratio of nerve terminals to acetylcholine receptors were significantly greater (p < 0.05) in the NMP group than in the ST group. Electromyography elicited TA muscle compound action potentials upon stimulation of the RLNs and ACNs. In rats, NMP implantation is efficacious for reducing atrophic changes in the TA muscle in the presence of partial RLN innervation.