ABSTRACT
Cerebellar disorders are classified in terms of aetiology, clinical features, pathological appearances, inheritance and, increasingly, molecular genetic abnormalities. Developmental malformations of the cerebellum give rise to the syndrome of congenital ataxia. Pathologically, many cases show features of pontoneocerebellar or granule cell hypoplasia. Friedreich’s ataxia is the most common early onset hereditary ataxia with a frequency in the UK of approximately 1–2 per 100 000. X-linked ataxia causes cerebellar ataxia with lower limb spasticity and hyper-reflexia. Skeletal and cardiac abnormalities are absent and progression is variable. The intermittent metabolic ataxias of childhood are rare. Affected children have a fluctuating cerebellar ataxia which tends to appear for a few weeks and then remit. Seizures, episodes of coma and cognitive impairment are often associated. Vitamin E deficiency is also associated with abetalipoproteinaemia and hypobetalipoproteinaemia. Mitochondrial diseases are characterized by defective mitochondrial respiration as a result of a complex and extensive range of mitochondrial or nuclear gene mutations.
