A Craniometric Analysis of Cranial Base and Cranial Vault Differences in Patients with Sagittal Synostosis
Anthony Azzolini, MD, Katherine Magoon, BS, Daniel Mazzaferro, MD, Robin Yang, MD, DDS, Scott P. Bartlett, MD, Jordan W. Swanson, MD, Jesse A. Taylor, MD.
Children's Hospital of Philadelphia, Philadelphia, PA, USA.
The emergence of newer, more powerful analytic technologies has allowed for more accurate 2 and 3-dimentional segmentation and measurements of stacked CT data. Craniofacial Surgeons have utilized this technology previously to perform detailed craniometric analysis of metopic, unicoronal, and bicoronal craniosynostosis patients, demonstrating statistically significant differences in craniometric angles and distances-from-midline measurements. We hypothesize that performing the same craniometric analysis of patients with sagittal synostosis will show significant, objective differences when compared to unaffected controls.
A retrospective case-controlled cohort analysis of patients with non-syndromic sagittal synostosis was performed. Computer tomography scans of the head were analyzed using Mimics (Materialise; Leuven, Belgium) to calculate craniometric angles, distances from midline, and cranial index. Mean measurements based on laterality were compared for each group. Absolute differences in measurements based on laterality were calculated. Averages were compared between groups. Statistical analysis was computed using Kruskal-Wallis, Wilcoxon rank sum, and paired t-tests.
Twenty-two patients with non-syndromic craniosynostosis and 19 controls were identified. Cranial indices, nine landmarks from midline, and six intracranial angles were measured. Most distances and angles demonstrated no difference from controls. The Petrous Ridge Angles (PRA) were significantly larger in the sagittal group compared to control (P=0.002, P=0.0187). The Interoccipital Angles (IOC) and the Right and Left Euryon to Zygomaticofrontal suture Angles (Ezf) were significantly more acute (P=<0.001, P=0.0022, P=0.0041, respectively). Not surprisingly, the Cranial Index was significantly smaller (P=0.0001). There was no significant transverse lateralization of skull base structures relative to midline as seen with metopic and unicoronal synostosis, and the cranial base deformity was relatively symmetric around the sagittal plane.
Our study provides a true, objective craniometric analysis of the cranial vault and endocranial base in patients with sagittal synostosis. While there is no significant transverse lateralization of structures of the anterior skull base relative to midline, there are significant, symmetric, differences in craniometric angles including IOA, EzFA, and PRA. Further investigation is needed to determine the volumetric implications of these findings, as well as the implications of cranial vault remodeling on cranial base dimensions.
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