Morphometric Analysis of the Posterior Cranial Fossa in Syndromic and Nonsyndromic Craniosynostosis

Posterior cranial fossa (PCF) anatomy can be abnormal in craniosynostosis, and hindbrain herniation may occur. This study analyzed PCF anatomy in single suture and complex craniosynostosis.Children with craniosynostosis and age-matched controls were identified. Cephalic index (CI) for cranial vault and PCF as well as tentorial (TA) and occipital angles (OA) were measured on preoperative imaging.Children with syndromic (N = 6), bicoronal (N = 4), sagittal (N = 12), and metopic synostosis (N = 4) as well as controls (N = 10) were enrolled. Mean CI for cranial vault was 0.89, 0.93, 0.65, 0.74, and 0.78, respectively. Corresponding CI for PCF was 0.81, 0.93, 0.62, 0.74, and 0.78. Mean TA and OA were 45.4° and 96.6° in syndromic, 39.7° and 87.0° in bicoronal, 34.0 and 75.0° in sagittal, 39.7° and 87.0° in metopic synostosis, and 42.9° and 88.3° in controls.While CI, TA, and OA in metopic synostosis were similar to controls, abnormalities were found in syndromic, bicoronal, and sagittal synostosis. Syndromic and bicoronal craniosynostosis patients had a higher CI for both cranial vault and PFC as well as larger TA and OA, indicating a brachycephalic skull with steep tentorium and narrow PCF. In sagittal synostosis, CI for cranial vault and PCF were lower and TA and OA smaller, reflecting scaphocephalic deformity also at PCF, with a flat tentorium. This study provides basic PCF morphometry in craniofacial conditions.