Scaphocephaly in a select South African population: a morphometric analysis of the cranial fossae and ventricular access points.

Abstract

Scaphocephaly is a cranial deformity that results from premature fusion of the sagittal suture and is characterized by an elongated and narrowed skull. Patients with this condition present with varying clinical features including frontal bossing and occipital protrusion. This study comprised two subsets, analysing different aspects related to this cranial deformity. Most morphological and morphometrical studies in patients with scaphocephaly focus on the cranial vault. Literature on the morphometry of the cranial base and its fossae in these patients is sparse. Therefore, the first subset aimed to analyse and compare the morphometry of the cranial fossae in patients with scaphocephaly. Due to varying cranial morphology among patients with these deformities, ventricular access using conventional techniques is often a challenge. Although ventricular access may not be frequently required in paediatric scaphocephalic patients, it is vital that an ideal location of the access points be established for safe ventricular catheterization. Accordingly, the second subset aimed to document the morphometry of Kocher’s and Frazier’s points in scaphocephalic patients using known craniometric and surface anatomical landmarks. Dimensions of the anterior, middle and posterior cranial fossae (ACF, MCF and PCF) were measured using select anatomical landmarks on computed tomography (CT) scans of 24 consecutive patients diagnosed with scaphocephaly between 2014 and 2020, and 14 non-affected/ normal paediatric patients selected as controls. Parameters of Kocher’s and Frazier’s points were measured in relation to known cranial surface anatomical landmarks on scans of the scaphocephalic patients utilized in subset 1. The study found that ACF and PCF are most affected in scaphocephalic patients, with elongation along the anteroposterior (AP) plane (lengths) (ACF, p=0.041 and PCF, p=0.018). Minimal changes were observed in the transverse plane (widths) in scaphocephaly versus non-affected/normal controls. Regarding subset 2, Kocher’s point was located between 91.6mm and 140mm posterior to the nasion, and between 20.5mm and 34.6mm lateral to the midline in patients with scaphocephaly. Frazier’s point was located between 60.9mm and 82.8mm superior to the inion, and 25.9mm and 41.4mm lateral to the midline. Parameters measured in the AP plane were found to be more affected than those measured lateral from the midline. This study contributes to the literature by providing novel morphometric data based on a select South African population. Data obtained could aid craniofacial surgeons in understanding which cranial fossa is most affected in scaphocephaly and to what extent, to decide on the most appropriate method of treatment. Additionally, the study concluded that the traditional landmarks used for ventricular access are relatively unreliable in scaphocephalic patients. This study provides data for neurosurgical consideration regarding ventricular catheterization procedures in patients with scaphocephaly.