Evidence of supratentorial hydrocephalus with a markedly narrowed fourth ventricle. Patent aqueduct of Sylvius with flow void.
Small-sized posterior fossa with low insertion of the tentorium, low torcula, and abnormal course of the straight sinus.
Evidence of downward herniation of cerebellum and brainstem through the foramen magnum. A tectal peaking sign of inferior colliculus is seen on the sagittal view as well as a cerebellar wrapping sign around the brain stem.
Thinning of the corpus callosum along with retrograde CSF permeation are noted.