Masseter muscle replacement in hemifacial microsomia by means of a functional free flap transfer

Alexander Cárdenas-Mejía, Department of Plastic and Reconstructive Surgery, Hospital General “Dr. Manuel Gea González,” Mexico City, Mexico Damián Palafox, Department of Plastic and Reconstructive Surgery, Hospital General “Dr. Manuel Gea González,” Mexico City, Mexico

Hemifacial microsomia (HFM) is characterized by different degrees of mandibular hypoplasia, ear malformations, facial nerve paralysis, and other clinical manifestations related to the underdevelopment of soft tissue and skeletal anatomical structures resulting ultimately in facial asymmetry. Masseter muscle is commonly involved with variable severity on the affected side in patients with HFM. We present the case of a patient with HFM who underwent a gracilis free flap transfer both as a replacement for the masseter muscle (a functional reconstruction surgery) and as a facial reanimation procedure. During the first stage, we performed a cross-facial nerve graft. Eight months later, we carried out the second stage of the treatment protocol once the viability of the nerve graft had been confirmed by neurophysiological studies. A free gracilis muscle flap was harvested in a standard fashion. Vessel anastomoses were performed under surgical microscope magnification (Zeiss Pentero) in an end-to-end fashion to the facial vessels, while nerve coaptation was then performed in an end-to-end fashion to the cross facial nerve graft and end-to-side to the ipsilateral masseteric nerve. In this particular case, we sought to use the gracilis free flap transfer to replace the absent volume secondary to the severe congenital underdevelopment of the masseter muscle, and also, to provide a facial reanimation procedure. In our experience, the gracilis free flap transfer has proven to be effective both as a replacement for the masseter muscle (a functional reconstruction surgery) and as a dynamic facial microsurgical reanimation procedure.

Keywords: Hemifacial microsomia. Facial reanimation. Free gracilis flap transfer. Reconstructive microsurgery. Masseter muscle.