Morphometric analysis of the craniocervical junction in patients with myelomeningocele: Evaluation of its relationship with chiari malformations and hydrocephalus

Objective: Spina bifida is the most common congenital anomaly of the central nervous system that is compatible with life. The most common and most severe form is myelomeningocele (MMC). MMC is an open dysraphism due to a closure defect in the caudal part of the neural tube that occurs at the 3rd week of gestation. Unlike other spinal dysraphisms, it is associated with many intracranial malformations (80% hydrocephalus, 86% Chiari Type II). The high incidence of these pathologies accompanying MMC reveals the necessity of explaining the pathogenesis of these congenital and chronic anomalies. Disturbances in craniospinal hydrodynamics have been associated with conditions such as hydrocephalus, craniovertebral junction anomalies, Chiari malformations, and craniosynostosis. It is aimed to understand the pathophysiology of MMC and related anomalies by examining the craniocervical junction morphometry. Materials and Methods: 77 patients with MMC who were treated and followed up by Ankara City Hospital Neurosurgery Clinic between 2019-2023 were evaluated retrospectively, together with preoperative MR images, and comparisons were made with craniocervical junction measurements. Statistical analysis of the data was performed using IBM SPSS Statistics v26 software. Statistical significance value was accepted as p≤0.05. Results: Tonsillar herniation, supraocciput length and Boogard angle were found to be significant risk factors for the development of hydrocephalus. A one-unit increase in tonsillar herniation in its own unit (mm) increases the risk of developing hydrocephalus 1.075 times, and this is statistically significant (p=0.009). In patients with hydrocephalus, compared to patients without; supra-occiput length and Wackenheim angle increased, Boogard angle and pB-C2 distance decreased. It was found that as the level of tonsillar herniation increased, the basion-dens interval length decreased and the supraocciput length increased. Conclusion: Significant correlations were found with hydrocephalus and Chiari malformations in craniocervical junction measurements of MMC patients. It is expected that comprehensive craniocervical junction morphometric analysis has not been performed in MMC patients before, the process that started with this study will pave the way for further evaluations and provide additional information about the etiopathogenesis of MMC and related anomalies. Thus, it should be aimed to predict the prognosis and contribute to the management of treatment and follow-up processes.