Cerebellar hypoplasia is a neurological condition in which the cerebellum—the part of the brain that coordinates movement—is smaller than usual or not completely developed. Cerebellar hypoplasia is a feature of a number of congenital (present at birth) brain malformation syndromes, inherited metabolic disorders and neurodegenerative disorders that begin in early childhood.

In an infant or young child, symptoms of a disorder that features cerebellar hypoplasia might include:

• floppy muscle tone
• developmental or speech delay
• problems with walking and balance
• seizures
• intellectual disability
• involuntary side to side movements of the eyes

In an older child, symptoms might include:

• headache
• dizzy spells
• clumsiness
• hearing difficulty

There is no standard course of treatment for cerebellar hypoplasia. Treatment depends upon the underlying disorder and the severity of symptoms. Generally, treatment is symptomatic and supportive.

Some of the disorders that are associated with cerebellar hypoplasia are progressive, which means the condition will worsen over time, and will most likely have a poor prognosis. Other disorders that feature cerebellar hypoplasia are not progressive, such as those that are the result of abnormal brain formation during fetal development and might have a better outcome.