D152. Computed Tomography Analysis of Mandibular Asymmetry Progression in Patients with Unilateral Craniofacial Microsomia

PURPOSE: Craniofacial microsomia (CFM) is associated with varying degrees of mandibular hypoplasia resulting in facial asymmetry. We seek to examine the differences in growth rates between affected and unaffected mandibular sides in unilateral CFM patients to better determine optimal timing of surgical intervention. METHODS: Patients with unilateral CFM from 2009-2023 with multiple facial CT scans were identified. Mandibular cephalometric measurements, including mandibular ramus height and body length, were obtained from head CT scan using three-dimensional analysis. Mandibular growth rates were modeled using multivariable linear regression and compared using a linear mixed effects model. RESULTS: Twenty-eight patients were included in the analysis with CT scans acquired from ages 5-22 years. Based on Pruzansky-Kaban classification, there were 5 class I, 12 class IIA, and 11 class IIB mandibles. Seventeen patients underwent mandibular distraction. Mandibular ramus height growth rate was similar between affected and unaffected sides (0.8 vs 1.2 mm/month, p=0.118). No differences were also observed based on subclass analysis of class I, IIA, or IIB mandibles. Following distraction, the growth rate of the mandibular ramus height was found to be greater in the affected side compared to the unaffected side (1.8 vs 0.8 mm/month, p=0.001). CONCLUSION: Ramus height discrepancy in patients with unilateral CFM is nonprogressive. This was consistent within the individual Pruzansky-Kaban classes. Mandibular distraction may accelerate ramus growth in the postoperative period. As we continue to analyze more data, we hope to further delineate any differences between Pruzansky-Kaban classes and the effects of surgery on mandibular growth.