Inferior herniation of the cerebellar tonsils through the foramen magnum with compression of the spinal cord against the basilar invaginated odontoid process projecting above the foramen magnum indenting the craniocervical junction of the spinal cord.
Expansion of the spinal cord parenchyma starting just below the foramen magnum and continuing inferiorly to the level of the conus medullaris by heterogeneous fluid signal.
Mild dilatation of the supratentorial ventricular system namely the third ventricle and lateral ventricles is seen.
Thickened calvarial bones. Enlarged adenoidal tissue