Nerve Switch for Reducing Synkinesis After Gracilis Muscle Transfer Innervated Via the Masseter Nerve

Background: In surgical treatment for longstanding facial paralysis, muscle transplantation is considered a useful and important method. To obtain a spontaneous smile, the use of the facial nerve of the healthy side as a motor source is better, but use of the masseter nerve allows prompt reinnervation and powerful movement. However, in some patients in whom the masseter nerve is used, separating masticatory movement and commissure contraction is difficult. Solutions for such patients have not been determined. Case History and Discussion: A 46-year-old female patient presented with longstanding complete facial paralysis after resection of a right acoustic neurinoma. As initial surgery, free gracilis transfer was performed on the cheek, but the patient experienced commissure movement during meals postsurgery. Secondary corrective surgery was performed to detach the motor nerve of the gracilis from the masseter nerve and suture it to the facial nerve of the healthy side via cross-face nerve graft. The symptom improved but partially recurred. Improvement in synkinetic movement can be obtained by performing cross-face nerve grafting and subsequent nerve switch.