Orbital Foramina Morphometrics in Non-Syndromic Unilateral Coronal Craniosynostosis
Helen Liu1, Abigail Katz1, Pierce L. Janssen1, Joshua Lacoste1, James G. Napoli2, John W. Rutland1, Eloise Stanton3, Bradley N. Delman1, Mark M. Urata3, Peter J. Taub1
1Icahn School of Medicine at Mount Sinai, New York, NY; 2American Museum of Natural History, New York, NY; 3Keck School of Medicine at the University of Southern California Children's Hospital Los Angeles, Los Angeles, CA; 4MedStar Georgetown University Hospital, Washington, DC
BACKGROUND: Non-syndromic unilateral coronal craniosynostosis (UCS) is a rare congenital disorder that results from premature fusion of either coronal suture. Unilateral fusion restricts growth between the ipsilateral frontal and parietal bones, leading to complex bony dysmorphogenesis in the calvarium, orbit, and skull base. Prior studies have reported associations between UCS and visual abnormalities such as astigmatism, strabismus, and decreased visual acuity. This study utilizes novel geometric morphometric analysis to compare dimensions of orbital foramina on synostotic versus nonsynostotic sides in patients with UCS.
METHODS: Computed tomography (CT) head scans of pediatric UCS patients were converted into 3D mesh models using 3D Slicer, an open-source software. Mean age at time of CT scan was 8.4 months. Anatomical borders of left and right orbits, supraorbital foramina, infraorbital foramina, optic foramina, and foramina ovales were plotted with by a single trained team member. Orbital and foraminal dimensions were measured and compared between synostotic and nonsynostotic sides. Additionally, medical records were examined to quantify prevalence of visual abnormalities in this patient cohort.
RESULTS: A total of 27 patients with non-syndromic UCS were included in this study (17 right UCS, 10 left UCS). Visual abnormalities were reported in 22 of 27 UCS patients (77.8%). Astigmatism (66.7%), anisometropic ambylopia (44.4%), and motor nerve palsies (33.3%) represented the three most prevalent ophthalmologic abnormalities in this cohort. Morphometric comparisons of orbits and orbital foramina are shown in Table 1. Orbits on synostotic sides were 11.3% narrower (p<0.001) with 21.2% less volume (p=0.028) than orbits on nonsynostotic sides. Average widths, circumferences, and areas were similar between synostotic and nonsynostotic sides upon comparison of supraorbital foramina, infraorbital foramina, optic foramina, and foramina ovales.
CONCLUSIONS: Patients with UCS have a high prevalence of visual abnormalities, with nearly 80% in this cohort of 27 patients having at least one deficit. Morphometric findings in this anatomical study highlighted some bony orbital changes associated with UCS. As demonstrated in prior studies, orbits in this study were smaller and narrower on ipsilateral synostotic sides than contralateral nonsynostotic sides. Despite this relative asymmetry in total orbital volume, there were no measurable differences in supraorbital foramina, infraorbital foramina, optic foramina, or foramina ovales dimensions on side-to-side comparison. Theoretical compression or distortion of vital neurovascular structures within bony orbital foramina does not seem to be a likely etiology of visual abnormalities in UCS patients. Future studies should examine the role of ocular and/or neuro-ophthalmologic pathology in the process.
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