Cross-facial nerve grafting as an adjunct to hypoglossal-facial nerve crossover in reanimation of early facial paralysis: clinical and electrophysiological evaluation.
Reanimation of a spontaneous and synchronous smile, and sufficient depressor mechanism of the lower lip presents a surgical challenge in facial paralysis. Hypoglossal-facial nerve crossover and cross-facial nerve grafting are the best options if the mimetic muscles around the mouth are still viable in patients in whom the facial nerve was sacrificed at the brainstem. Although good muscle tone and facial motion have been obtained by hypoglossal-facial nerve crossover, smile is dependent on conscious tongue movement. Cross-facial nerve grafting provides a voluntary and emotion-driven smile, but requires two coaptation sites, which leads to substantial axonal loss and a long regeneration time. This method was not successful in activating the depressor mechanism. The first stage is the classic "baby-sitting" procedure, in which the bulk of the mimetic muscles was maintained by the rapid reinnervation of the hypoglossal-facial nerve crossover during the regeneration period of the cross-facial nerve graft, and temporalis muscle transfer to the eyelids is performed. During the second stage, the cross-facial nerve graft that used the thickest zygomaticobuccal branch on the healthy side was coapted with the corresponding branches on the paralyzed side. The hypoglossal-facial nerve crossover continued to innervate the depressor muscles. Good spontaneous smile and sufficient depressor mechanism were achieved by cross-facial nerve grafting and hypoglossal-facial nerve crossover respectively, and these techniques are demonstrated by the authors clinically and electrophysiologically.