[Differential Diagnosis of Idiopathic Cerebellar Ataxia].

Cortical cerebellar atrophy has been defined as a sporadic degenerative cerebellar disorder other than multiple system atrophy, whereas the term "idiopathic cerebellar ataxia (IDCA)" has been recently proposed by a Japanese expert group. There is no diagnostic biomarker for IDCA; therefore, the diagnosis largely depends on exclusion of other cerebellar diseases, such as multiple system atrophy and hereditary spinocerebellar ataxia. Other important differential diagnoses include immune-mediated cerebellar ataxia, such as Hashimoto's encephalopathy, gluten ataxia, anti-glutamic acid decarboxylase-positive cerebellar ataxia, alcoholic cerebellar degeneration, and drug-induced ataxia. Secondary cerebellar disorders are treatable and should be recognized and screened.