神経血管柄付き遊離広背筋弁による顔面神経麻痺の再建

Using a Free Latissimus Dorsi Muscle Flap with a Neurovascular Pedicle to in Reconstruction for Facial Nerve Paralysis

はじめに

　顔面神経麻痺は患者に身体的，心理的，社会的に深刻な影響を与える疾患である。その治療法のなかで，神経血管柄付き遊離広背筋弁移植を用いた笑いの再建は，（患者の）上述のような影響を和らげるのに有用な手段の1つである。われわれは意識して作る笑顔ではなく，感情に反応して自然に現れる笑顔こそ真の笑いであると考え，それを容易に実現するために，力源とする神経は健側顔面神経を基本としている。広背筋弁は支配神経である胸背神経を長く（通常の成人で13～15 cmほど）採取できるため，健側の顔面神経を力源とした再建が一期的に可能である。

　本稿では，片側性顔面神経麻痺に対する遊離広背筋弁による再建について，広背筋の特徴を生かして改良を加えて，「目元の笑いに焦点を当てた新しい方法」を解説する。

　Facial nerve paralysis significantly impacts patients physically, psychologically, and socially. One effective treatment is reconstructing the patientʼ ability to smile by using a free latissimus dorsi muscle flap with a neurovascular pedicle. This method prioritizes un-self-conscious, natural smiling by using the contralateral facial nerve for reanimation. The latissimus dorsi muscle is advantageous due to its long thoracodorsal nerve, enabling one-stage reconstruction.

　Facial reanimation techniques include contralateral facial nerve-based gracilis muscle transfer (e.g., two-stage gracilis muscle transfer or one-stage latissimus dorsi transfer) and masseter nerve-based gracilis muscle transfer. Although the former technique enables natural smiling, it may result in weak muscle movement. The latter technique provides strong contraction at an early timepoint but not spontaneous, emotion-driven smiling, and it may cause involuntary movements while chewing. To overcome these drawbacks, a dual-nerve approach using both contralateral facial and masseter nerves has been developed as discussed herein.

　A modified 2024 technique refines previous methods by using a V-shaped muscle flap to elevate both the mouth and lower eyelid, improving natural smiling. This new method optimizes the nerve supply and mitigates excessive masseter nerve-driven movement. We also discuss the surgical procedures, post-operative care, and potential complications such as weak movement or nerve injury. The new technique continues to evolve to enhance aesthetic and functional outcomes.