Characterization of nigrostriatal dysfunction in spinocerebellar ataxia 17

Extrapyramidal signs are a main feature of spinocerebellar ataxia 17 (SCA17). However, the extent of dopaminergic dysfunction and its correlation with parkinsonian signs are not fully understood. In order to define this, we investigated five subjects from three different families with a pathological CAG/CAA expansion in the TATA-binding protein gene (SCA17), ranging from asymptomatic carrier to patient with advanced disease, by FP-CIT SPECT. Nigrostriatal dysfunction was present in patients manifesting a fully developed phenotype but not in preclinical and early stages. Dopamine transporter reduction was symmetrical and uniform in caudate and putamen and it correlated with the clinical severity of ataxia.