Comparing Outcomes in Patients Treated with Chemodenervation Versus Surgery for Facial Synkinesis: A Systematic Review and Meta-Analysis

Introduction: Outcomes for chemodenervation treatment of facial synkinesis are well described, and evidence for surgical interventions such as selective neurectomy and myectomy is growing. There is minimal comparative data on outcomes between selective neurectomy and/or myectomy versus chemodenervation. Objectives: To compare facial synkinesis treatment with chemodenervation compared with surgery as measured by standardized outcome measures. Methods: A systematic review of three databases was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Included studies used validated facial nerve outcome measurements (patient-graded, physician-graded, or semiautomatic) for chemodenervation or surgical treatment for patients with facial synkinesis. Studies were excluded if free muscle transfer was performed. Meta-analysis was performed on studies using the same outcome measure, and risk of bias assessment was performed using Cochrane Review systems. Results: In total, 36 studies (1171 total patients) were included in the review. Chemodenervation and surgery both demonstrated benefit as measured by the Facial Clinimetric Evaluation Scale and Sunnybrook scale, without a difference between treatment types ( p = 0.76 and p = 0.061, respectively). Synkinesis Assessment Questionnaire scores improved more with chemodenervation than with surgical treatment (mean 15.45 vs. 5.90 improvement, p < 0.0001). For semiautomated objective measurements using Emotrics software, myectomy produced more improvement in dental show compared to neurectomy (13.28 mm vs. −4.89 mm, p < 0.0001) and more oral commissure excursion than neurectomy or chemodenervation (3.79 mm vs. 1.60 mm vs. 1.00 mm, respectively, p < 0.0001). Conclusions: Although most commonly used together, comparative analysis suggests that selective neurectomy and/or myectomy produce similar improvements in facial synkinesis compared to chemodenervation when assessed with patient surveys or clinician-graded tools. However, high interstudy heterogeneity and confounding covariates limit definitive conclusions, and more data from surgical treatments are needed.