COMPARISON OF STRIATAL F-18 DOPA UPTAKE IN ADULT-ONSET DYSTONIA-PARKINSONISM, PARKINSONS-DISEASE, AND DOPA-RESPONSIVE DYSTONIA

We studied six patients with adult-onset dystonia-parkinsonism (DYS-P) with F-18-6-fluorodopa (F-18-dopa) positron emission tomography and compared their influx constants (K(i) values) with those of six patients with classical childhood-onset dopa-responsive dystonia (DRD), 12 age-matched Parkinson's disease (PD) patients without dystonia, and 21 normal controls. The DYS-P group had significantly reduced mean caudate (67% of normal) and putamen (45% of normal) F-18-dopa uptake. These K(i) values were similar to mean caudate and putamen K(i) values obtained for the PD group. In contrast, the DRD group showed minor reductions in mean caudate (9%) and putamen (18%) F-18-dopa uptake when compared with normals. The mean caudate:putamen K(i) ratio was 1.7 in the DYS-P group and 2.1 in the PD group. In the DRD and normal groups, the caudate:putamen ratios were close to unity. The findings of this study are that adult-onset DYS-P targets the nigrostriatal dopaminergic projections in a pattern similar to PD, with the putamen being more affected. This provides support for the hypothesis that DYS-P may be a phenotypic variant of Lewy body disease. DYS-P seems distinct from childhood-onset DRD, in which striatal F-18-dopa uptake is either normal or only mildly reduced.