Early masseter to facial nerve transfer may improve smile excursion in facial paralysis

Background: Masseter-to-facial nerve transfer has been shown to be an effective and safe treatment option in patients with acute and subacute facial palsy. The present article aims to characterize whether there is a benefit in early nerve transfers while minimizing other confounding variables; we present a study that consist of only patients with complete facial nerve paralysis resulting from intratemporal facial nerve resections. Methods: Between 2012 and 2016, 7 masseter-to-facial nerve transfers were performed for complete facial nerve palsy after intratemporal proximal nerve resections. Pre- and postoperative photographic and video evaluations were performed using both the Sunnybrook facial grading scale and the MEEI FACE-gram software for more objective metric measurements. Statistical analysis was performed to determine which patient and surgical variables had significant effects on outcome. Results: Mean 14-month follow-up revealed that patients who underwent nerve transfer prior to 6 months' denervation achieved postoperative oral commissural excursion of 11.1mm versus 6.5mm in patients who underwent nerve transfer after 6 months (P = 0.003). Performing masseter-to-facial nerve transfer to the main facial nerve trunk resulted in a significantly higher improvement in the modiolus-philtral ratio (31.6% versus 6.1%) than selective transfer in patients (P = 0.01) at the latest follow-up. Conclusions: Early masseter-to-facial nerve transfers, before 6 months of palsy duration, can potentially improve smile excursion and symmetry of open mouth smile. Additionally, truncal coaptations may provide improved tone over coapting to selective facial nerve branches. These findings necessitate larger studies regarding the importance of denervation time with fifth-to-seventh nerve transfers.