Isolated Dandy-Walker malformation

A rare non-syndromic central nervous system malformation characterized by the association of three signs: hydrocephalus, partial or complete absence of the cerebellar vermis, and posterior fossa cyst contiguous with the fourth ventricle, presenting early in life with hydrocephalus, bulging occiput and posterior fossa signs such as cranial nerve palsies, nystagmus and ataxia.