MR FINDINGS IN PONTOCEREBELLAR HYPOPLASIA

We present four cases with combined hypoplasia of the cerebellum and t he ventral pens pontocerebellar hypoplasia (PCH). PCH represents an au tosomal recessive neurodegenerative disorder with fetal onset. The dis ease is rare, with less than 20 cases having been reported. The main f indings of PCH and the inclusion criteria for our cases can be summari sed as progressive microcephaly from birth, pontocerebellar hypoplasia documented by MRI and marked chorea, which may change, later in child hood, to more dystonic patterns. The cerebral cortex becomes progressi vely atrophic. Motor and mental development are delayed, and epilepsy, mainly tonic-clonic seizures, is frequent. The MRI features in all of our cases were: (1) Hypoplastic cerebellum situated close to the tent orium, The hypoplastic cerebellum has a reduced number of folia, in co ntrast to the normal number of thin folia in simple cerebellar atrophy . (2) The cerebellar hemispheres are reduced to bean-like or wing-like structures, The cerebellar hemispheres appear to 'float' in the poste rior fossa. (3) Markedly hypoplastic ventral pens. (4) Slight atrophy of the supratentorial gyral pattern, (5) Dilated cerebromedullary cist ern and fourth ventricle, (6) Delayed myelination of the white matter. (7) No significant disorganisation of brain architecture and no sever e corpus callosum defect.