Reinnervation of Long Term Denervated Thyroarytenoid Muscle by the Nerve-muscle Pedicle Transplantation

Abstract

We had previously demonstrated that an immediate nerve-muscle pedicle (NMP) transplantation to denervated thyroarytenoid (TA) muscle was effective in the recovery from atrophic changes due to successful reinnervation in rats. However, in a clinical situation, we usually treat patients suffering from persistent unilateral vocal fold paralysis. The objective of this study was to examine the effects of NMP transplantation on long-term denervated TA muscle in rats.
Ten Wistar rats were divided into two groups; animals treated with left recurrent laryngeal nerve (RLN) transection alone (DNV group) and animals treated with NMP method at 16 weeks after RLN transection (NMP group). Both groups were euthanatized at 26 weeks after RLN transection. We evaluated the status of the neuromuscular junction (NMJ) and the muscle area histologically.
In the NMJ, the ratio of the number of nerve terminals to that of acetylcholine receptors in the NMP group was significantly higher than that in the DNV group (p<0.01). With reference to the muscle areas, the ratios of the treated side to the normal side of the entire muscle and that of the individual muscle fibers in the NMP group were significantly higher than those in the Denervated group (p<0.01, p<0.05, respectively).
Our study supported that up to 16 weeks after denervation, successful reinnervation can be established in denervated TA muscle by the NMP method.