陳旧性顔面神経麻痺に対する遊離筋肉移植術の歴史と変遷

抄録

　　Neurovascular free muscle transfer for facial reanimation was first reported by Harii, et al in 1976. Although the restoration of strong and powerful contractions upon smiling was encouraging, these patients also exhibited involuntary muscle contractions with biting, most likely because the obturator nerve innervating the gracilis muscle was sutured to the ipsilateral deep temporal nerve that innervates the temporal muscle.
　　To overcome this problem, a two-stage operation combining the cross-facial nerve graft with the free-muscle transfer was developed. This method enables the use of the contralateral facial nerve, which results in a significant probability of achieving spontaneous synchronous animation. Surgeons therefore applied this method using different free-muscles, including the gracilis, pectoralis minor, rectus abdominis, and latissimus dorsi muscles. However, the long recovery period associated with this strategy may dissuade patients from choosing this treatment
　　One-stage reconstruction, in which the motor nerve is directly crossed through the face and sutured to the contralateral facial nerve branches, may shorten the duration until recovery of motor function. In 1981, Mayou described 10 cases of one-stage reconstruction using the extensor digitorum brevis muscle, followed by some new methods developed by other surgeons using the abductor halluces, gracilis, rectus abdominis, and latissimus dorsi muscles. However, its power as a motor source is sometimes weak because only some small branches of the facial nerve, not the whole trunk, can be used.
　　In 1993, Harii, et al. therefore developed the one-stage latissimus dorsi muscle transfer in which the thoracodorsal nerve was crossed across the face through the upper lip and hooked up to the branch of the contralateral facial nerve. This method allowed for strong contraction due to innervation by the contralateral facial nerve, which promised more natural facial movement. However, approximately 10% of cases had weak contraction despite innervation from the contralateral facial nerve branches.
　　To overcome the disadvantages with the contralateral facial nerve, the ipsilateral masseteric nerve was reconsidered as an alternative motor source approximately 10 years ago. Cortical adaptation between the nerve centers of the trigeminal and facial nerves was found to coordinate the motor activity of smiling. This hypothesis must be confirmed using functional MRI.
　　Recently, in order to gain the benefits of both nerves, dual innervation muscle transfer was developed. However, whether this method is superior to conventional methods is unknown. In this report, the history of neuro-vascularized free muscle transfer for treatment of established facial paralysis is described.