Masseter nerve transfer with dual function for smile and eye closure

In patients with facial nerve palsy, the masseter nerve (MN) transfer may be used to improve orbicularis oculi (OO) resting tone and eye closure. This study evaluated OO muscle function after "selective" MN transfer compared to upper cross face nerve graft (CFNG) in patients with facial nerve palsy. This retrospective study included adults with facial nerve palsy who underwent CFNG and selective MN transfer for dual reinnervation of OO and zygomaticus major. Outcomes included electromyography evidence of OO reinnervation, clinical assessment, Sunnybrook Facial Grading System to assess symmetry, synkinesis, resting and dynamic eyelid position, and eMotrics for eye closure assessment. The study included 16 patients (mean age at surgery: 53 years; mean time from injury to surgery: 6.7 months; mean follow-up, clinical: 29.4 months and video: 20.6 months). Postoperatively, there were significant improvements in resting symmetry for the cheek (p<0.001), and symmetry of voluntary gentle eye closure (p=0.004) and smile (p<0.0001). Postoperative synkinesis was observed with gentle eye closure and open mouth smile (mean score 0.44). Postoperative electromyography revealed innervation of OO via MN transfer in all patients (n=13) and CFNG in 5 patients. Postoperative eyelid position was significantly different at the marginal reflex distance with MN transfer activation (p<0.01). Selective MN transfer is effective in facilitating eye closure via functional innervation of the OO with the activation of the nerve transfer. Owing to the importance of eye closure for corneal protection, the selective MN transfer should be considered in patients undergoing surgery for facial reanimation.