PET imaging of the pre-synaptic dopamine uptake sites in rapid-onset dystonia-parkinsonism (RDP)

BACKGROUND: Rapid-onset dystonia-parkinsonism (RDP) is a genetic movement d isorder characterized by abrupt onset over hours to days of bradykinesia, p ostural instability, dysphagia, dysarthria, and severe dystonic spasms with decreased levels of the dopamine metabolite, homovanillic acid (HVA), in c erebrospinal fluid (CSF). METHODS: We imaged the dopamine re-uptake system with [O-methyl-C-11]beta-C FT ([C-11]beta-CFT) in three severely affected individuals with RDP and fou r patients with idiopathic Parkinson's disease (IPD). Results were compared with those of age-matched normal volunteers. RESULTS: Positron emission tomography images from those patients with TPD d emonstrated a dramatic reduction in the volume of distribution of [C-11]bet a-CFT whereas patients with RDP showed slightly elevated values. CONCLUSIONS: The data suggest that patients with RDP do not have a decrease in the number of dopamine re-uptake sites. Our findings suggest that, unli ke the situation in TPD, low CSF HVA concentrations seen in RDP patients ar e not the result of degeneration of striatal dopamine terminals or loss of dopamine re-uptake sites.