How different from “normal” are the cranial base and vault of infants with nonsyndromic, single-suture sagittal synostosis (NSSS)? This study quantitatively addresses this question utilizing computed tomography (CT) analytic technology.
Head CT scans of infants with NSSS and normocephalic controls were analyzed using Mimics to calculate craniometric angles, distances, and segmented volumes. Craniometric measurements and asymmetry indices were compared between NSSS and control groups using linear regressions controlling for age. Ratios of anterior-, middle-, and posterior-to-total cranial vault volume were compared between groups using beta regressions controlling for age.
Seventeen patients with NSSS and 19 controls were identified. Cranial index and interoccipital angle were significantly smaller in NSSS compared with controls (P = 0.003 and <0.001, respectively). Right—but not left—external acoustic meatus angle and internal acoustic meatus-to-midline distance were significantly greater in NSSS than in controls (P = 0.021 and 0.016, respectively). NSSS patients and controls did not significantly differ in any asymmetry indices, except for the articular fossa angle asymmetry index (P = 0.016). Anterior vault volume proportion was greater in NSSS relative to controls (proportion ratio = 1.63, P < 0.001). NSSS trended toward a smaller posterior vault volume proportion (P = 0.068) yet did not differ in middle vault volume proportion compared with controls.
In this small study, patients with nonsyndromic, single-suture sagittal craniosynostosis had relatively similar cranial base measurements, and larger anterior vault volumes, when compared with controls. Further work is needed to confirm the possibility of rightward asymmetry of the anterior cranial base.