Morphologic Differences between Normocephalic and Scaphocephalic Sagittal Craniosynostosis

Abstract

Background: Nonsyndromic single-suture sagittal craniosynostosis presentation spans scaphocephalic and normocephalic head shapes. The authors studied craniometric differences between scaphocephalic and normocephalic groups with sagittal synostosis.

Methods: Head computed tomography scans of 40 patients with sagittal synostosis (20 with scaphocephaly and 20 with normocephaly) and age- and sex-matched controls were analyzed, including cranial base angles, distances from midline, and intracranial volumes.

Results: Cranial index was significantly decreased in index groups compared with controls ( P < 0.001). Right external acoustic meatus angle was significantly larger in patients with scaphocephaly ( P < 0.001) and left external acoustic meatus angle was significantly smaller in patients with normocephaly ( P = 0.002) when compared with controls. Midline angular analysis showed that bifrontal angle was significantly smaller among patients with scaphocephaly versus controls ( P = 0.026). Cranial base distances from midline were longer to the right and left internal acoustic meatus and shorter to the euryon-to-zygomaticofrontal suture for both groups of patients versus their controls ( P < 0.05). Scaphocephalic patients had a larger anterior cranial volume ratio (18% versus 13%; P < 0.001) and normocephalic patients had a larger posterior volume ratio (42% versus 33%; P < 0.001) than controls. Scaphocephalic patients had larger anterior volume ratios than normocephalic patients (1.66 versus 1.16; P = 0.025), but smaller posterior compartment volume ratios (0.90 versus 1.53; P < 0.001).

Conclusions: Rightward asymmetries of the linear and angle cranial base measurements existed in both index groups. Intracranial volume distribution lies anteriorly in patients with scaphocephaly but posteriorly in patients with normocephaly. These data show craniometric evidence that although normocephalic and scaphocephalic patients share the diagnosis of sagittal synostosis, they are morphometrically different from each other and from controls.