The effect of neurocranial surgery on basicranial morphology in isolated sagittal craniosynostosis.

OBJECTIVE: Isolated sagittal craniosynostosis produces a scaphocephalic neurocranium associated with abnormal basicranial morphology, providing additional evidence of the developmental relationship of the neurocranium and basicranium. Corrective surgical procedures vary, but the immediate impact of the surgical procedure is restricted to the neurocranium. This study addresses the secondary effects of neurocranial surgery on the cranial base. DESIGN: Three-dimensional (3-D) computed tomography (CT) scans were obtained for preoperative (n = 25) and postoperative (n = 12) patients with isolated sagittal synostosis. Landmark data from 14 landmarks on and around the cranial base were collected from 3-D CT reconstructions and analyzed using Euclidean distance matrix analysis. Subsamples of age-matched patients were used to identify basicranial differences in pre- and postoperative patients and to compare postoperative growth patterns identified in longitudinal data with preoperative growth patterns characterized in cross-sectional data. RESULTS: Statistically significant differences (p < or = 0.10) were found in the morphology of the cranial base in preoperative and postoperative patients. The relative positions of the landmarks nasion, right asterion, and left asterion are similar in preoperative and postoperative patients. However, the position of these landmarks relative to the cranial base is different in the two groups, being positioned relatively more anteriorly in postoperative patients. In addition, we found that the cranial base angle, on average, neither increases nor decreases in the first postoperative year. These morphological differences are associated with divergent growth trajectories in the operated and unoperated cranial base. CONCLUSION: Regardless of specific procedure, neurocranial surgery in sagittal synostosis patients affects growth patterns of the cranial base. The lack of change in the postoperative cranial base angle suggests that neurocranial surgery alleviates the occipital rotation and decreased cranial base angle described in the sagittal synostosis basicranium.

Three-dimensional morphological analysis of isolated metopic synostosis.

Morphological differences were quantified in three-dimensions among individuals with untreated isolated metopic synostosis and between those individuals and similar aged-matched normal dry skulls to test two hypotheses: first, that the dysmorphology is a self-correcting condition; and second, that a lack of vertical growth of the skull produces this dysmorphology. Three-dimensional (3D) coordinates were recorded for 22 craniofacial landmarks from CT scans of 15 metopic patients, ranging from 5- to 32-months-old, and of four normal dry skulls, ranging in age from 6- to 36-months-old. The patient population was diagnosed with isolated metopic synostosis at The Johns Hopkins Medical Institutions in Baltimore, Maryland or Children's Hospital in St. Louis, Missouri. Comparisons between the metopic age groups indicate that the trigonocephalic phenotype worsens through time. Between 5 and 14 months, the neurocranium displays an increase in vertical growth. This was followed by a lack of vertical growth between 14 and 32 months. The face displays a lack of vertical growth from 5 to 14 months and an increase in vertical growth after 14 months. Comparisons between the metopic age groups and the normal skulls indicate that the trigonocephalic head is taller superoinferiorly and longer anteroposteriorly. Relative to the normal phenotype, the inferior temporal region in the metopic phenotype is narrow. These findings enabled the rejection of both hypotheses and localized form differences between normal and metopic phenotypes. Based on these results, we suggest that the trigonocephalic phenotype worsens with age and the amount of vertical growth that produces the trigonocephalic phenotype varies throughout growth with respect to location within the skull and age.