Irreversible muscle contracture after functioning free muscle transplantation using the ipsilateral facial nerve for reinnervation

Four patients who underwent functioning free muscle transplantation (FFMT) for facial reconstruction developed a progressive disfiguring muscle contracture. This complication has not been previously reported. Three of the patients had longstanding facial paralysis and were reanimated by FFMT. The fourth patient had left hemifacial atrophy but without facial paralysis. She also underwent FFMT for augmentation. All four FFMTs were innervated by the ipsilateral facial nerve. Initially, they all had a normal facial appearance at rest during the first few months after FFMT. However, they all developed a progressive severe muscle contracture from 6 to 12 months after FFMT. Continuous spontaneous electrical impulse activity, which stimulated the transferred muscle day and night, may be responsible for the progressive muscle contracture. From the patients' reported sensations and from clinical evaluation, which included a local xylocaine injection test, over-reinnervation with a synkinesis effect of the transferred muscle is hypothetically the main cause, not over-tension of the muscle itself. This complication may possibly be avoided by limiting or decreasing the number of fascicles from the ipsilateral facial nerve or better by using a cross-facial nerve graft instead of the ipsilateral facial nerve as the innervating motor nerve. The outcome with a cross-facial nerve is likely to be more predictable and reliable.