Management of synkinesis.

Facial synkinesis is one of the most distressing consequences of facial paralysis. Synkinesis refers to the abnormal involuntary facial movement that occurs with voluntary movement of a different facial muscle group. The pathophysiologic basis of facial synkinesis is likely multifactorial although the predominant mechanism appears to be aberrant regeneration of facial nerve fibers to the facial muscle groups after facial nerve injury. Patients experience hypertonic contractures and synkinetic movements such as eye closure with volitional movement of the mouth or midfacial movement during volitional or reflexive eye closure. Synkinesis can cause functional limitation with activities such as eating, drinking, smiling, and may even lead to social isolation. Evaluation of synkinesis is primarily subjective with facial grading scales such as the Sunnybrook scale. Objective measures of synkinesis using computerized video analysis show promise although no objective techniques are currently widely used. The most common therapeutic modalities for the treatment of facial synkinesis include (1) botulinum toxin type A (BTX-A) injections for selective chemodenervation of affected muscle groups and (2) facial neuromuscular retraining. Biofeedback using mirrors or electromyography has been used both for the treatment and prevention of facial synkinesis. Other treatment options include surgical therapies, such as selective neurolysis or myectomy, although these have been rendered nearly obsolete with the advent of BTX-A.