Nerve-muscle pedicle implantation facilitates re-innervation of long-term denervated thyroarytenoid muscle in rats

Abstract

Nerve-muscle pedicle (NMP) implantation was effective in the recovery from atrophic changes in long-term denervated thyroarytenoid (TA) muscle. Re-innervation occurred via the transferred nerve. However, the effectiveness of the NMP method may decline with increasing duration of denervation.To evaluate the effects of NMP implantation on long-term denervated rat TA muscle.Wistar rats (n=105) were divided into two groups in which the left recurrent laryngeal nerve (RLN) was transected without (DNV group) or with (NMP group) subsequent NMP implantation, and subgroups of each group were formed depending on the period after RLN transection (immediate to 48 weeks). In the DNV subgroups, we histologically assessed the area of muscle and the number of neuromuscular junctions. In the NMP subgroups, we performed electromyographic, videolaryngoscopic, and histologic assessments. The muscle area and muscle action potentials were evaluated by comparing the treated and untreated sides. The ratio of the number of nerve terminals to that of acetylcholine receptors was also assessed.The TA muscle area was significantly larger in most of the NMP subgroups compared with the DNV subgroups. Muscle action potentials were present in all NMP animals. All histologic and physiologic assessments revealed degradation as the denervation period in the five NMP subgroups.