Composite Sterno-Omohyoid Functional Muscle Transfer for Dual-Vector Smile Reanimation: A Case Series

Background: Facial reanimation flaps often add bulk and produce single-vector smiles, and multivector flaps frequently require challenging intramuscular dissection. Objective: To evaluate the effectiveness of sterno-omohyoid flap (SOHF) transfer for dual-vector smile reanimation by measuring upper dental show and oral commissure movement. Methods: SOHF transfers from 2017 to 2020 were retrospectively evaluated using eFACE and Emotrics software. Results: Four patients with flaccid and one with nonflaccid facial paralysis were identified (four females and one male, median age: 39 years (range: 38-65); two acoustic neuromas, two congenital, one temporal bone fracture). Median follow-up was 20 months (range: 14-26). All flaps received masseteric nerves and two had additional cross-face grafts. Four developed contraction [median time to contraction: 5.5 months (range: 3-10)]. Mean oral commissure excursion and dental exposure improvements were 7.6 ± 4.0 mm (p = 0.03) and 2.9 ± 1.8 mm (p = 0.05), respectively. Dynamic, smile, and midface-smile eFACE improvements were 20.3 ± 6.8 (p = 0.007), 25.5 ± 14.5 (p = 0.03), and 50.5 ± 12.0 mm (p = 0.004) points, respectively. Mean SOHF mass was 14 ± 1.7 g. Conclusion: The SOHF is a small flap that provides dual-vector smile reanimation in flaccid and nonflaccid facial paralysis.