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.
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