Once facial sequela has established in facial palsy patients with severe nerve impairment, the facial nerve functions can hardly be restored completely. The most unpleasant sequelae of facial palsy are facial synkinesis and facial contracture. First, we developed an objective method (% eye opening) to evaluate oral-ocular synkinesis, which refers to involuntary eye closure during mouth movements. We used % eye opening as an index of oral-ocular synkinesis, and showed that biofeedback rehabilitation using a mirror prevented the development of facial synkinesis in patients with facial palsy. We then developed a combined strategy of botulinum toxin injection and mirror biofeedback rehabilitation for the treatment of established facial synkinesis. A single injection of botulinum toxin provided transient relief from facial synkinesis, and the mirror biofeedback rehabilitation maintained this improved state for a long time in patients with facial palsy. Because facial synkinesis develops as a result of aberrant regeneration of an impaired peripheral facial nerve, we hypothesized that the mirror biofeedback rehabilitation induces cortical reorganization in the facial motor cortex. Furthermore, we developed an objective method for measuring the cheek asymmetry using a 3D scanner to evaluate another sequela of facial palsy, namely, facial contractures. We used the cheek asymmetry rate as an index and showed that a single injection of botulinum toxin provided transient relief also from facial contracture in patients with facial palsy.
