Cortical adaptation to restoration of smiling after free muscle transfer innervated by the nerve to the masseter

Background: The child with Mobius 14 syndrome presenting for facial reanimation presents a difficult challenge. When bilateral paralysis and paresis preclude use of the contralateral facial nerve, the authors' preferred donor nerve for reinnervation of free muscle transfer is a branch of the trigeminal nerve, the ipsilateral nerve to the masseter. Methods: The authors have used a branch of the trigeminal nerve as a donor for three children with Mobius syndrome. Results: Of three children with Mobius syndrome, two are now able to smile independently of jaw closure. One child is now 2.6 years past bilateral free gracilis transfers completed at age 13.2 years. The second child is 8.2 years past free gracilis transfer to the left side of the face performed at age 7.6 years. The third child is 5.6 years past bilateral facial reanimation with free latissimus and free gracilis flaps completed at age 13.4 years. This child is not able to smile independently of jaw closure. The two who are able to smile independently of jaw closure demonstrated maximum excursion of the lateral commissure on the affected sides when asked to smile without biting; however, they demonstrated minimal excursion of the lateral commissure on the affected sides when asked to bite without trying to smile. Conclusions: These findings indicate that smiling independently of jaw closure is attainable with reanimation to the masseteric branch, refuting previous speculations. Early age at operation and absence of complete bilateral paralysis in these two children may have contributed to cortical adaptation to smiling.