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Microsurgical Strategies in 74 Patients for Restoration of Dynamic Depressor Muscle Mechanism: A Neglected Target in Facial Reanimation

The facial depressor muscles are an essential component of a full denture smile. In addition, the depressor muscles are actively used to express other human emotions such as sadness, anger, depression, and sorrow. Despite advances in microsurgical techniques, it is surprising how little effort has been directed toward reanimation of the lower lip. This article presents innovative approaches used in 74 patients by the senior author since 1981 for the dynamic reanimation of depressor muscle function. The surgical techniques include transfer of the anterior belly of the digastric muscle (n = 22) and transfer of the platysma muscle (n = 26) as a pedicled muscle to the corner of the mouth. Other surgical interventions used are the mini-hypoglossal nerve transfer to the cervicofacial branch of the ipsilateral facial nerve (n = 20), direct neurotization of the depressor muscles (n = 6), and facial-to-facial nerve transfer. The depressor muscle function was graded by four observers after reviewing standard preoperative and postoperative videotapes. Rating of the functional and aesthetic results was done according to the following arbitrary scale: excellent (2), good (1.5), moderate (1), fair (0.5), and poor (0). Sixty-nine percent of the patients who had a digastric muscle transfer displayed good to excellent results, and 24 percent showed moderate restoration of the depressor mechanism postoperatively. Eighty-three percent of patients who had platysma transfer to the lower lip demonstrated good to excellent outcome, and 11 percent had moderate depressor muscle function. In the hypoglossal nerve transfer group, 72 percent of the patients achieved good to excellent results and 15 percent had moderate function of the depressor mechanism. Of the patients who underwent direct neurotization, 34 percent showed good to excellent depressor muscle function postoperatively and 66 percent achieved fair depressor muscle function. Excellent outcome was noted in the patient with VII to VII nerve transfer. In conclusion, this article presents innovative approaches to restore dynamic depressor muscle function, which so far has been a neglected area of facial reanimation.