Exploring Progression and Differences in Facial Asymmetry for Hemifacial Microsomia and Isolated Microtia: Insights from Extensive 3D Analysis.

ABSTRACT

BACKGROUND: Aiming to measure and compare asymmetry of facial hard and soft tissues in patients with HFM and isolated microtia, examining how it evolves. METHODS: This cross-sectional study assessed facial asymmetry in male East Asian patients aged 5-12 diagnosed with unilateral hemifacial microsomia (Pruzansky-Kaban types I and IIA) or isolated microtia. Using 3D imaging of computed tomography scans, it measured root-mean-square (RMS) values for surface deviations across facial regions. Statistical analyses explored differences between conditions and the relationship of age with facial asymmetry. RESULTS: A total of 120 patients were categorized into four groups by condition (HFM or isolated microtia) and age (5-7 and 8-12 years). Patients with HFM exhibited the greatest asymmetry in the lower cheek, while those with isolated microtia showed primarily upper face asymmetry. Significant differences, except in the forehead and nasal soft tissue, were noted between the groups across age categories. Notable distinctions in hard tissue were found between age groups in the nasal and mid-cheek areas for patients with HFM (median RMS (mm) 0.9 vs. 1.1, P = 0.02; 1.5 vs. 1.7, P = 0.03) and in the nasal and upper lip areas for patients with isolated microtia (median RMS (mm) 0.8 vs. 0.9, P = 0.002; 0.8 vs. 1.0, P = 0.002). Besides these areas for HFM, no significant age-asymmetry correlation was detected. CONCLUSIONS: Significant differences in facial asymmetry were observed between HFM and isolated microtia, with the asymmetry in specific area evolving over time. LEVEL OF EVIDENCE IV This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .