Selective Reinnervation of Posterior Cricoarytenoidmuscles by Upper Root of Unilateral Phrenic Cerve / 听力学及言语疾病杂志

ABSTRACT

Objective To study the experimental results of selective reinnervation of posterior cricoarytenoid(PCA) muscles by upper root of unilateral phrenic nerve.Methods Eight beagle dogs were used in this experiment.The left recurrent laryngeal nerves (RLNs) were severed and anastomosed with upper root of phrenic nerve, and the intralaryngeal adductor branch was cut and sutured into the belly of the ipsilateral PCA muscle. The right RLNs were kept intact, and were used as control group.Videolaryngoscopy and electromyography (EMG) were performed at preoperative, immediately after surgery and 6 months after surgery.After completion of all physiologic testings,the dogs were sacrificed and bilateral PCA muscles and intralaryngeal part of recurrent laryngeal nerves were harvested, then histological examination was carried out.The laryngeal nerve was stained with toluidine blue and the morphology of the axons was observed under light microscope.Results Preoperatively, the movement of bilateral vocal folds were normal in all dogs.The left vocal folds were fixed immediately after surgery, 6 months after surgery, the left vocal folds in all 8 dogs recovered inspiratory abductive movement.Spontaneous and evoked electrical activities of the reinnervated PCA muscles could be recorded in all cases during inspiration preoperatively.The left PCA muscles were electrical silent during normal inspiration, and evoked activities were not induced immediately after surgery.Spontaneous electrical activities and evoked electrical activities were recorded 6 months after surgery, and had no significant difference when compared with those of postoperative (P>0.05).There was no significant difference in the cross-sectional area of the bilateral posterior cricoarytenoid muscles fibers after the masson staining.Muscle collagen relative cross-sectional area and collagen relative cross-sectional area and muscle/collagen cross-sectional area ratio difference were not statistically significant(P>0.05).Nerve pulp numbers of left and right sides of the recurrent laryngeal nerves had no significant difference (P>0.05).Conclusion Selective reinnervation of posterior cricoarytenoid muscles by the upper root of unilateral phrenic nerve can restore inspiratory vocal fold abduction to a satisfactory extent and avoid aberrant regeneration.