Spontaneous Smile Reconstruction Using Latissimus Dorsi Muscle Transfer in a Patient Who Had Previously Undergone Hypoglossal-Facial Nerve Anastomosis to Treat Facial Paralysis After Acoustic Neuroma Resection

Facial paralysis is a potential complication of acoustic neuroma treatment, and hypoglossal-facial nerve anastomosis (HFA) is a well-established reconstructive option. We report a case of dynamic facial reanimation using a free latissimus dorsi (LD) muscle flap in a patient previously treated with HFA who remained unable to produce a spontaneous smile. A 64-year-old woman, 5 years postacoustic neuroma resection and subsequent HFA, presented with preserved facial tone but distressing involuntary synkinetic movements and inability to smile spontaneously. A V-shaped neurovascular LD muscle flap was harvested and innervated primarily by the contralateral facial nerve (CLFN), with end-to-side coaptation of the distal stump of the thoracodorsal nerve (TDN) to the ipsilateral masseteric nerve (ILMN). The zygomatic branch innervated by the hypoglossal nerve was selectively transected to mitigate adverse eyelid movements, and its end was coapted to the distal stump of the TDN to preserve orbicularis oculi tone. Postoperatively, the patient achieved synchronous oral commissure elevation and lower eyelid movement, effectively restoring a true spontaneous smile and a "smiling eye" appearance. To the best of our knowledge, this is the first report of CLFN-innervated LD muscle transfer for smile reanimation following HFA. This combination may offer a viable strategy to restore natural facial expressions in patients with complete facial paralysis.