Evaluation of the effect of melatonin administration on nerve regeneration after recurrent laryngeal nerve injury in rats

INTRODUCTION AND AIM: Recurrent laryngeal nerve (RLN) injury, is an important complication encountered in anterior neck surgery. Although nerve recovery is observed after the treatment, the functional results are not very satisfactory. Although there are many studies on nerve regeneration, no definitive effective treatment has been established. In our study; We aimed to evaluate the effect of suturing and melatonin treatment on nerve regeneration after RLN incision. METHOD: Our study; we used 28 male Wistar Albino Rats. Left RLN incision was made in all subjects. Post-incision nerve repair was performed only in the first and fourth groups. The third and fourth groups were given 10 mg/kg intraperitoneal melatonin daily for six weeks. Transoral laryngeal EMG was applied to all subjects before, after the procedure, at the third and sixth week, and vocal cord movements were evaluated by laryngeal examination. At the end of six weeks, all the subjects were sacrificed and the larynx and trachea tissues were histologically examined. RESULTS: After the procedure, left vocal cord paralysis(VCP) was observed in all subjects. In the sixth week; Bilateral vocal cords were observed to be mobile in three subjects in the first group and four subjects in the fourth group. With EMG, the highest motor unit potential amplitude value was recorded in the fourth group in the third and sixth weeks. Histologically, an increase in the number of Schwann cells, a decrease in axon damage and cytoplasmic vacuolization were observed in the fourth group compared to the other groups. CONCLUSION: In our study, laryngoscopic examination, electrophysiological and histopathological findings show us that melatonin contributes to peripheral nerve healing.