Genetic and clinical patterns of heritable cerebellar ataxias in adults. II. Clinical manifestations.

Clinical data on 244 probands with spinocerebellar types, 163 with late cortical cerebellar atrophies (LCCA), and 180 with olivopontocerebellar atrophies (OPCA) were analysed. Spinocerebellar cases were divided into three according to their estimated genetic mechanisms: recessive, dominant, or sporadic. Ages of onset were identical in sporadic spinocerebellar types, LCCA, and OPCA, the average being about 50. They showed highly correlated clinical patterns. In the light of other evidence, these diseases may represent a premature aging process in the central nervous system, probably determined multifactorially. Recessive spinocerebellar cases were very few. There were 127 cases of spinocerebellar types with dominant inheritance, characterised by age of onset around 33, colourful ocular signs, and spasticity. A large family with this disease was described in which 34 patients were affected through five generations. The computed tomograms showed an almost normal cerebellum and electronystagmograms indicated patterns of vestibulocular impairment. No necropsied case was available among the present material, but in pathological reports of similar cases, major lesions were found in the ventral and the dorsal spinocerebellar tracts, Clarke's columns, and the posterior columns in the spinal cord. This disease, or hereditary spastic ataxia, represented a fairly well-defined entity inherited dominantly among a group of cases with spinocerebellar types, and it was separable from LCCA or OPCA, not only on clinical and genetic grounds, but by a predominantly spinal involvement.