Preoperative morphology and development in sagittal synostosis

The goal of this study is to characterize the differences between normal cranial morphology and that of patients diagnosed with isolated sagittal synostosis, using three-dimensional (3D) landmark coordinate data collected from computed tomography (CT) scans. This retrospective study uses pre-operative CT images of a sample of children diagnosed with isolated sagittal synostosis (N = 23) and of dry skulls of unaffected children (N = 10). In order to be included in the study, patients had to have a confirmed diagnosis of sagittal synostosis and a pre-operative CT scan of acceptable quality available in digital format. Separation of normal and synostosed individuals on the basis of craniofacial morphology was achieved by applying a principal coordinates analysis to a dissimilarity matrix calculated from the landmark coordinate data. Direct comparison of age-graded samples of normal and synostosed individuals using Euclidean Distance Matrix Analysis enabled localization of the morphological differences between samples. This method was also used to characterize growth patterns of the two samples using cross-sectional data. The parietal bosses were found to be the features that were most influential in separating sagittal synostosis patients from their age-matched normal counterparts. A cross-sectional analysis of growth showed that the specifics of the growth differences between normal and sagittal synostosis individuals changed with the age interval considered. We present direct evidence that the parietal bosses are critical in the differentiation of normal and sagittal synostosis morphology, and indirect evidence of the possible role of the parietal tubers in the etiology of sagittal synostosis.