Is There a Difference in Orbital Volume Between Affected and Unaffected Sides in Patients With Unilateral Craniofacial Microsomia?

PURPOSE: Craniofacial microsomia (CFM) is characterized by malformations of structures derived from the first and second pharyngeal arches. The orbit is variably affected. The purpose of this study was to determine whether there is a difference in orbital volume between affected and unaffected sides in patients with unilateral CFM. The specific aims were to 1) measure orbital volume, 2) compare affected and unaffected sides, 3) evaluate the correlation between clinical evaluation of orbital size and volumetric measurement, and 4) determine whether there is a correlation between orbital volume and severity of mandibular deformity.

MATERIALS AND METHODS: This study is a retrospective case series of patients with unilateral CFM from Boston Children's Hospital (Boston, MA) who had a computed tomographic (CT) scan. Manual segmentation of the orbit using Mimics software (Materialise, Leuven, Belgium) was performed on CT images of the 2 orbits. The predictor variable was laterality (affected vs unaffected side) and the primary outcome variable was orbital volume. Wilcoxon signed rank test was used to compare these measurements and determine whether the affected side differed from the unaffected side. The correlation between orbital volume and Pruzansky-Kaban type of mandibular deformity, as documented in the medical record, was determined using the Spearman rank correlation coefficient.

RESULTS: Thirty-nine patients were included. Orbital volume was 10% smaller on the affected side (P = .001) in 80% of patients. There was no correlation between orbital size and severity of mandibular involvement.

CONCLUSION: The results of this study showed a marked difference in orbital volume between affected and unaffected sides in patients with unilateral CFM. These differences were small and might not be clinically relevant. Orbital volume did not correlate with severity of mandibular deformity.