Basilar Invagination and Platybasia

Sagittal computed tomography image shows severe superior migration of the dens across the foramen magnum. Exaggerated cervical spine lordosis is also present.

Sagittal computed tomography image shows a nearly horizontal configuration of the clivus. In addition, the dens and atlas are positioned far superior to the level of Chamberlain’s line. Also note the diffuse osteopenia.