PONTO-CEREBELLAR HYPOPLASIA WITH DYSTONIA - CLINICO PATHOLOGICAL FINDINGS IN A SPORADIC CASE

Microcephaly, absent psychomotor development and dystonic limb movemen ts were the main clinical features of a 3-year-old girl affected by hy poplasia of the pontocerebellar structures. As in the few previously r eported cases there are discrepancies between the severity of lesions in the supratentorial and infratentorial compartments. Pathological fe atures such as size reduction of the ventral pens, inferior olive atro phy, dentate nucleus fragmentation, and thinning of the cerebellar cor tex suggest an impaired maturation of the involved structures due to a prenatal condition (dated at about 20-28 weeks of gestation). Somatot opic analysis failed to provide conclusive evidence on the primary tar get of the disease. The affected structures originate from the dorsal rhombencephalic region at about the same gestational age, and their ma turation is probably under the control of sets of genes which regulate pattern formation. Early abnormal functioning of such genes might lea d to the selected morphogenetical alterations observed in ponto-cerebe llar hypoplasia. The normal morphogenetic pattern of the supratentoria l structures and the mild lesions observed suggest that their late inv olvement can be related to a different pathogenetic process.