Segmental masseteric flap for dynamic reanimation of facial palsy

The masseter muscle is one of the major chewing muscles and contributes to define facial contour. It is an important landmark for aesthetic and functional surgery and has been used for facial palsy reanimation or as source of donor motor nerve. We present an anatomic study to evaluate the possibility of using a muscle subunit for dynamic eye reanimation. Sixteen head halves were dissected under magnification to study the neurovascular distribution and determine safe muscle subunits; areas of safe/dangerous dissection were investigated. Once isolated, the arc of rotation of the muscular subunit was measured on fresh body to verify the reach to the lateral canthus. The patterns of neurovascular distribution and areas of safe dissection were identified; the anterior third of the muscle represents an ideal subunit with constant nerve and artery distribution. The muscle is too short to reach the lateral canthus; a fascia graft extension is needed. The information provided identified the main neurovascular branches and confirms the feasibility of a dynamic segmental flap. The need of efficient motor units for facial reanimation demands for different surgical options. A detailed anatomic description of the neurovascular bundle is mandatory to safely raise a functional motor subunit.