Masseteric-to-facial nerve transfer combined with static suspension: Evaluation and validation of facial symmetry in patients with different levels of asymmetry.

One-stage combined dynamic reanimation with static suspension has obvious advantages of improving facial symmetry. In clinical observation, patients with different levels of oral commissure drooping achieve different symmetry outcomes, despite undergoing the same surgical procedure. Patients with slight asymmetry obtain better outcomes than those with severe asymmetry. The mechanisms influencing postoperative outcomes have not been systematically explored. We retrospectively analyzed 44 patients performed with masseteric-to-facial nerve transfer combined with static suspension. Patients were divided into two groups according to the level of oral commissure drooping: slight-asymmetry group (n = 24) and severe-asymmetry group (n = 20). Static and dynamic symmetry were assessed with FACE-gram software pre and postoperatively. The symmetry of the oral commissures at rest and during smiling significantly improved postoperatively in all patients. The differences of the bilateral oral commissure positions were significantly smaller in slight-asymmetry group than that in severe-asymmetry group (p<0.001), indicating that slight-asymmetry group achieved better symmetry. Furthermore, these differences were caused by the oral commissures position on the unaffected side, both pre and postoperatively (p<0.001), but not the paralyzed side's (p>0.05). In conclusion, masseteric-to-facial nerve transfer combined with static suspension achieved dynamic and static symmetry in patients with different levels of asymmetry. Patients with slight asymmetry obtained better postoperative symmetry than those with severe asymmetry. Postoperative facial asymmetry might be influenced by the hypertonicity of facial muscles on the unaffected side.