Skull Base and Craniocervical Anomalies in Syndromic Craniosynostosis

In patients with syndromic craniosynostosis, early synostosis of the cranial base synchondroses may occur, potentially increasing the frequency of abnormalities in the cranial base. We aim to estimate the prevalence of platybasia, basilar invagination, odontoid retroflexion, Chiari malformation type I (CMI), and cervical syringomyelia in patients with syndromic craniosynostosis. Furthermore, we aim to assess the changes in prevalence between the initial preoperative study and the latest available study for each patient.

This is a retrospective multicenter study involving patients with genetically confirmed syndromic craniosynostosis, using preoperative MRI. The latest follow-up MRI from these patients is also analyzed. Variables are measured in midsagittal MRI sequences. Metrics calculated include tonsillar herniation, basal angle, pB-C2, clivoaxial angle, and presence of basilar invagination and syringomyelia. Frequencies of these anomalies are described both overall and according to the specific syndrome. The differences between syndromes and between the initial and final studies are then statistically analyzed.

Preoperative MRI was analyzed for 77 patients, of which 56 had a subsequent study. In the preoperative cohort, 7.8% displayed CMI, with this feature solely seen in patients with Pfeiffer (33.3%) and Crouzon syndromes(19%). Platybasia was observed in 5.2% of patients, odontoid retroflexion in 2.9%, syringomyelia in 1.4%, and no patient presented with basilar invagination. By contrast, the follow-up cohort saw an increase in all anomalies in frequency (although the increase was only significant for CMI, with a prevalence of 21.4% [ P = .021]), except for platybasia, which was not present in any patient.

CMI is prevalent in Crouzon and Pfeiffer syndromes, but seldom found in others. Its onset progressively increases with age. Both basilar invagination and odontoid retroflexion are infrequent, with their frequency mildly elevating with age. Platybasia, although a rarity as well, displays a decrease in frequency as age advances.