(A425) Resting Tone After Masseteric-Facial Nerve Transfer: A Systematic Review

Introduction: Facial nerve paralysis significantly affects facial symmetry and function, leading to functional and psychosocial impairments. Masseteric to facial nerve transfer has emerged as a promising technique with past research showing its strength restoring dynamic smile, however, less is known about its impact on resting facial tone and spontaneous smile. The purpose of this systematic review is to determine whether masseteric to facial nerve improves resting tone and facial symmetry.

Methods: A systematic literature search was conducted using the PICO system search strategy. The population of interest was patients with confirmed facial paralysis, interventions was isolated masseteric to facial nerve transfer, and outcomes of interest were clinician graded facial nerve surveys and electrophysiologic assessments. PubMed, Embase, Web of Science, and Cochrane Library were searched through September 18th, 2024.

Results: A total of 329 studies were screened, with 45 undergoing full-text review, and 23 studies included for final analysis. Preliminary narrative synthesis was conducted, revealing that the most common outcomes for resting tone and spontaneous smile include the Sunnybrook Facial Grading System, eFACE scores, FaceGRAM, Emotrics software, and facial asymmetry index. Across studies, masseteric to facial nerve transfer had little to no impact on resting facial tone and spontaneous smile.

Conclusions: While masseteric to facial nerve transfer is effective in restoring dynamic voluntary smile, its impact on resting facial tone and spontaneous smile may be limited.