RESUMO
BACKGROUND: The treatment of post-paretic facial synkinesis is based on a combination of nonsurgical and surgical strategies. Even if improvements towards the restoration of a natural smile have been obtained with selective neurectomies (SN) and depressor anguli oris (DAO) myectomy, the lower lip frequently remains asymmetric and cranially displaced. The aim of this study was to evaluate the effect of the mentalis muscle on the position and symmetry of the lower lip in patients with synkinesis and to assess the added benefit of neurectomies of nerves innervating the mentalis muscle in improving the lower lip configuration and mandibular teeth show. METHODS: A retrospective cohort study on all patients affected by post-paretic synkinesis at our Institution was performed. A Non-mentalis Neurectomy Group including twelve patients treated with SN without targeting the branches to mentalis muscle was compared to a Mentalis Neurectomy Group, including sixteen patients who underwent additional specific mentalis branches neurectomies. All patients underwent DAO myectomy. Analyses of standardized images were performed with ImageJ software. RESULTS: Post-operative comparisons between the two groups showed superior and significant improvements in the Mentalis Neurectomy Group across all measures, including lower and upper border deviation (p=0.035 and p=.004, respectively), inclination of the lower lip (p=.019), and lower quadrant dental show (p=.004). CONCLUSIONS: The addition of targeted selective neurectomies to the branches innervating mentalis muscle significantly improved dental show and caudal position and symmetry of the lower lip during open mouth smile.
RESUMO
BACKGROUND: In post-paretic synkinesis, muscle tone imbalance between upper and lower lip depressors and elevators, results in the inability to produce an effective smile. Surgical treatments to improve smile, focus on restoring tonicity balance between peri-oral muscles by weakening hyper-toned muscles through selective myectomies or selective neurectomies. The goal of this study was to compare objective outcomes between selective myectomies alone with those of selective myectomies combined with selective neurectomies. METHODS: Retrospective cohort study performed on post-paretic synkinesis patients who underwent depressor anguli oris (DAO) myectomies or DAO and platysma myectomies with selective neurectomies. Objective outcomes included pre- and post-operative analyses of smile measures (excursion, angle, and dental show) and Botox administration (periorbital and platysmal). RESULTS: Thirty-seven pa tients underwent DAO myectomies only (myectomy group) and eighteen patients underwent DAO and platysma myectomies with selective neurectomies (myectomy-neurectomy group). Within group analyses showed significant angle improvement in both groups (p<.05) and improved smile excursion in the myectomy-neurectomy group (p<.05). Between group comparisons showed significant closed mouth smile excursion improvement (difference in means: -1.14 millimeters; 95% CI -2.19 to -0.09; p=.034) and significant decrease in platysmal Botox administration (difference in means: 27.36 Botox units ; 95% CI 18.72 to 36.00; p<.001) in the myectomy-neurectomy group compared to the myectomy group. CONCLUSIONS: This study suggests that selective myectomies and selective myectomies with selective neurectomies provide overlapping and differing benefits to peri-oral synkinesis. Selective neurectomies and platysma myectomy provided slightly improved excursion and significantly decreased botulinum injections to the platysma.