一侧膈神经上根选择性神经再支配环杓后肌的实验研究

摘要

目的 探讨一侧膈神经上根选择性神经再支配环杓后肌的可行性和有效性.方法 8只健康雄性青年Beagle犬作为实验动物,全麻下切断Beagle犬左侧膈神经上根与左侧喉返神经,两断端通过游离神经桥接的方式吻合,并将同侧喉返神经内收肌支切断并植入同侧环杓后肌中;右侧不做任何处理,作为正常对照侧.于手术前、神经修复术后即刻、术后6个月分别行电子喉镜和喉肌电图检查,在最后一次检查后处死动物,取双侧环杓后肌和喉内段喉返神经行组织学检查并与对侧比较.结果 术前8只犬的双侧声带运动正常,术后即刻左侧声带固定,术后6个月均恢复了吸气性外展运动.术前8只犬双侧环杓后肌均能记录到自发肌电位,并引出诱发电位;术后即刻左侧环杓后肌呈电静息,未记录到诱发电位;术后6个月均能记录到自发肌电位,并引出诱发电位,而且两种电位幅度分别与术前比较差异均无统计学意义(均为P>0.05).环杓后肌Masson染色示两侧肌肉纤维相对截面积、胶原纤维相对截面积、肌肉/胶原纤维截面积比差异均无统计学意义(均为P>0.05).喉内段喉返神经甲苯胺蓝染色后示神经纤维分布较均匀密集,且左右两侧喉返神经有髓神经纤维数量差异无统计学意义(P>0.05).结论 左侧膈神经上根选择性神经再支配环杓后肌能有效避免神经错向再生,恢复声带的生理性外展运动.%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.