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A Craniometric Analysis of Cranial Base and Cranial Vault Differences in Patients With Metopic Craniosynostosis

Purpose: The effect of synostosis is not confined to the immediate vicinity of the suture. The authors hypothesized metopic craniosynostosis results in migration of lateral structures from midline, and differences in segmental volume of the cranial fossa. Methods: A retrospective case-controlled cohort analysis of patients with nonsyndromic metopic craniosynostosis was performed. Craniometric angles, distances to landmarks from midline, cephalic index, and segmented volume ratios were calculated. A comparison group consisted of patients without cranial pathology or with mild positional plagiocephaly. Results: Twenty patients with metopic craniosynostosis and 19 controls were identified. The bifrontal angle was significantly more acute in metopic patients. Distance from midline to the medial carotid, the foramen ovale, and the hypoglossal canal were all significantly longer in metopic patients. Ratio of anterior third to total cranial vault volume was significantly smaller in metopic patients; however, ratio of middle third to total cranial vault volume was significantly larger. As the bifrontal angle decreased by 1°, the volume of the anterior third of the cranial vault was observed to decrease by 0.17% (P < 0.001). Conclusions: Patients with metopic craniosynostosis show a distinct and significant transverse lateralization of structures of the anterior skull base relative to midline, significant restriction of the anterior third of the cranial vault, and compensatory expansion of the middle third. There is a linear relationship between the bifrontal angle and the subsequent change in anterior third cranial vault volume. Level of Evidence: IV; Therapeutic