Hydrocephalus due to a Chiari II malformation

Sagittal T1-weighted magnetic resonance imaging (MRI) showing hydrocephalus due to a Chiari II malformation in a child with myelomeningocele. Note the shallow posterior fossa and descent of cerebellar tonsils past the foramen magnum. Other findings include large massa intermedia, low-lying torcula, and partial agenesis of the corpus callosum.