A 1 year-old boy had a history of a meningomyelocele repaired shortly after birth, and obstructive hydrocephalus requiring shunting.

This malformation is know as a Chiari malformation, type II. It is quite complex and associated with more serious consequences than the type I malformation. The type II malformation affects the entire hindbrain, dura and bone, as well as the spinal cord, the latter presenting as spina bifida and a meningomyelocele. Among the abnormalities included in this malformation are aqueductal stenosis, hydrocephalus, tonsillar herniation, a "kinked" medulla, an elongated 4th ventricle, fused colliculi resulting in a "beaked" tectum of the midbrain, partial agenesis of the corpus callosum, syringomyelia, and a dysplastic skull.