[Spinocerebellar degeneration in Japan--the feature from an epidemiological study].

A nationwide epidemiological study on spinocerebellar degeneration (SCD) including multiple system atrophy was performed in Japan from 1988 to 1989. The national prevalence rate of SCD was estimated to be 4.53/100,000 in 1987. The percentage of patients with each subtype of SCD was; olivopontocerebellar atrophy (OPCA) 34.4%, Menzel type of hereditary cerebellar ataxia (MHCA) 12.6%, Holmes type of hereditary cerebellar ataxia (HHCA) 7.5%, Shy-Drager syndrome (SDS) 7.0%, hereditary spastic paraplegia (HSP) 3.9%, dentatorubro-pallidoluysian atrophy (DRPLA) 2.5%, Friedreich ataxia (FA) 2.4%, Joseph disease (JD) 2.0%, and striatonigral degeneration (SND) 1.5% in decreasing order. In Japan, compared to European countries, non-hereditary types seemed to be commoner than hereditary types. OPCA was the most common disorder, but FA which is the most common disorder in European countries was found to be rare in Japan. We grouped the SCD on the basis of common pathological lesions, and compared the clinical features in the same group according to the severity stages. Similarity and differences in non-hereditary cerebellar form (LCCA, HHCA), multiple system atrophy (OPCA, SDS, SND), hereditary cerebello-brainstem form (MHCA, JD, DRPLA), and hereditary spinal from (FA, HSP) were elucidated. As to the functional status in SCD, there was a significant association between the severity of illness and the level of independence in each item of ADL, and also between poorer functional prognosis and presence of extrapyramidal and autonomic signs.