Discriminating bathrocephaly from sagittal synostosis: the diagnostic power of objective cranial metrics

Bathrocephaly is a benign cranial shape variant characterized by symmetric occipital prominence, often misdiagnosed as sagittal synostosis, which can lead to unnecessary imaging and surgery. This study aimed to develop objective morphometric criteria for distinguishing bathrocephaly from sagittal synostosis in infants using three-dimensional cranial metrics.

A retrospective cohort of pediatric patients with either bathrocephaly or sagittal synostosis, evaluated at our institution between 2023 and 2025, was analyzed. All patients underwent cranial computed tomography (CT) for diagnosis. Eleven patients with sagittal synostosis, sex-matched to the bathrocephaly group, were included. Cranial morphometrics-cephalic ratio (CR), radial symmetry index (RSI), cranial vault asymmetry (CVA), and cranial vault asymmetry index (CVAI)-were measured at 11 standardized axial levels via 3D surface imaging. Statistical analyses included t-tests, Mann-Whitney U, Fisher's exact test, and linear regression with age adjustment.

Bathrocephaly patients were significantly older than those with sagittal synostosis (33.6 ± 18.5 vs. 14.2 ± 4.2 weeks, p = 0.004), with similar sex distribution. Cephalic ratio values were significantly higher in the bathrocephaly group across almost all axial levels, especially in posterior regions (CR 2-8: p < 0.001, adjusted p < 0.001). No significant differences were found in RSI, CVA, symmetry ratios, or CVAI between groups. Presence of a persistent mendosal suture supported the diagnosis of bathrocephaly.

Objective morphometric analysis-primarily elevated posterior cephalic ratios and identification of mendosal suture patency-provides a reliable, noninvasive distinction between bathrocephaly and sagittal synostosis. This paradigm can reduce unnecessary CT imaging and surgical referral, supporting conservative management for infants with benign occipital variants.