<unk>  is characterized by reduced cerebellar volume, even though cerebellar shape is (near) normal. It consists of a heterogeneous group of disorders of cerebellar maldevelopment presenting as early-onset non–progressive congenital ataxia, hypotonia and motor learning disability. Various causes have been incriminated, including hereditary, metabolic, toxic and viral agents. It was first reported by French neurologist Octave Crouzon in 1929. In 1940, an unclaimed body came for dissection in London Hospital and was discovered to have no cerebellum. This unique case was appropriately named "human brain without a cerebellum" and was used every year in the Department of Anatomy at Cambridge University in a neuroscience course for medical students.<unk>  can sometimes present alongside hypoplasia of the corpus callosum or pons. It can also be associated with hydrocephalus or an enlarged fourth ventricle; this is called Dandy–Walker malformation.
Cerebellar hypoplasia
Cerebellar agenesis
Pontocerebellar hypoplasia
Olivopontocerebellar atrophy
Polycephaly
Fibular hemimelia
Acrania
Spotted lunulae