Atlanto-occipital assimilation: the role of ex-, basi-, and suboccipital bones in the physiopathology of type I basilar invagination. Patient series

CT with multiplanar and 3D reconstructions provides a comprehensive evaluation of atlanto-occipital assimilation in BI1. The condyle-mass complex was the most consistent assimilation site, while anterior and posterior arch fusions were variable. Atlanto-occipital assimilation in BI1 appears to extend beyond midline structures, involving consistent exoccipital-atlas lateral mass nonsegmentation. https://thejns.org/doi/10.3171/CASE25765.