EXPERIMENTAL-STUDY ON NEURORRHAPHY OF THE RECURRENT LARYNGEAL NERVE IN DOGS

The effectiveness of anastomosis of a divided recurrent laryngeal nerv e was evaluated in six adult mongrel dogs. Videolaryngoscopy and evoke d compound muscle action potentials in the intrinsic laryngeal muscles were performed at six months and the posterior cricoarytenoid muscles and recurrent laryngeal nerves were processed for histomorphometric s tudies. Recovery of compound muscle action potentials in all re-innerv ated muscles and histomorphometric findings confirmed a good grade of axonal regeneration. The most significant histomorphometric changes ob served were: a reactive hypertrophy of type I fibres in thr posterior cricoarytenoid muscles of there-innervated side, and a high nerve fibr e density in the distal stump to the anastomosis. However, incomplete recovery of motion and fasciculated movements of the re-innervated voc al folds were observed. Reduction of effective motor units in the re-i nnervated muscles might be a factor that cause incomplete restoration of vocal fold movements.