MRI in cerebellar hypoplasia.

Cerebellar hypoplasia may present with a wide variety of neurological and systemic features, ranging from aplasia causing neonatal death to mild hypoplasia in an asymptomatic adult. MRI clearly documents the size of the cerebellum and any associated abnormalities. We describe 7 cases of cerebellar hypoplasia of varying aetiology--3 inherited, 2 associated with spinal dysraphism, 1 with Joubert's syndrome and 1 with pontine agenesis, probably as a result of basilar artery infarction in utero. T1- and T2-weighted images were obtained in each case and gadolinium-DTPA was administered in one. Associated features such as a Chiari malformation (2 cases), brain stem hypoplasia (2 cases), Dandy-Walker cyst and pachygyria (3 cases) and spinal dysraphism (2 cases) were clearly identified. Accurate documentation of these appearances assists in genetic counselling.