Extrapyramidal motor signs in degenerative ataxias

Background: Extrapyramidal motor signs (EPS) are well-known symptoms of deg enerative ataxia. However, little is known about frequency and appearance o f EPS in subtypes of ataxia. Methods: We characterized 311 patients with ataxia clinically and genetical ly. Course of the disease and EPS were investigated according to a standard ized protocol. Diagnostic and prognostic impact of EPS in subtypes of ataxi a was analyzed by Kaplan-Meier plots. Results: Extrapyramidal motor signs occurred in all forms of ataxia, but fr equency and type of EPS varied between genetically and clinically defined s ubtypes. Postural tremor in hereditary ataxias was typical for spinocerebel lar ataxia type 2 (SCA2). Dystonia was generally rare in ataxias, but, if p resent, suggested SCA3. We observed a parkinsonian variant of SCA3 in which parkinsonism was present in the beginning of the disease and responded wel l to levodopa therapy, leading to diagnostic confusion. Parkinsonism in SCA 3 was independent of CAG repeat length but ran in families, suggesting modi fying genes. In idiopathic sporadic cerebellar ataxia (ISCA), EPS are more frequent in late-onset than in early-onset forms. In 50% of ISCA patients w ith parkinsonism, the diagnosis of multiple system atrophy remained questio nable because of normal autonomic function. Conclusions: Extrapyramidal motor signs can help to predict the genetic sub type of ataxia. Extrapyramidal motor signs were more frequent in genetic su btypes in which basal ganglia affection has been demonstrated by postmortem studies. However, no type of EPS was specific for an underlying mutation. In ISCA, EPS are an adverse prognostic factor. Parkinsonism is especially a ssociated with a more rapid course of the disease.