Clinical and [123I]FP-CIT SPET imaging follow-up in patients with drug-induced parkinsonism.

We recently found that patients with drug-induced parkinsonism (DIP) may have normal (group I) or abnormal (group II) putamen [(123)I]FP-CIT DAT (dopamine transporter) binding. In this study we reassessed clinical features and DAT binding in 19 of the original 32 patients (10 of group I and 9 of group II) after a 19-39-month follow-up period and tested the effects of chronic levodopa treatment in both cohorts of patients. In group I patients, [(123)I]FP-CIT SPET (single photon emission tomography) was still normal in all patients at follow-up; DAT binding and UPDRS (Unified Parkinson's Disease Rating Scale) motor score values did not differ from baseline. In group II patients, [(123)I]FP-CIT SPET was still abnormal at follow-up; putamen DAT binding was significantly reduced and UPDRS III score higher compared to baseline. Levodopa treatment improved motor symptoms in three out of ten patients of group I and in eight out of nine patients of group II. No adverse psychiatric effects were observed in any of the patients. This study shows that DAT binding imaging may help to identify subjects with DIP secondary to a loss of dopamine nerve terminals in the context of a progressive degenerative parkinsonism. Patients with DIP may benefit from levodopa therapy, particularly when dopamine nerve terminal defects are present, and this should be considered in the therapeutic management of these patients.

[123I]FP-CIT SPET imaging in drug-induced Parkinsonism.

We assessed the status of dopamine nerve terminals in patients treated with dopamine receptor blocking agents (DRBAs) who had developed drug-induced parkinsonism (DIP). We performed [(123)I]FP-CIT SPET in 32 consecutive patients who were on DRBAs for at least 6 months and developed extrapyramidal signs. The UPDRS-III was used to assess clinical severity. Twenty-six age- and sex-matched healthy subjects served as control group. Putamen [(123)I]FP-CIT SPET binding was reduced in 14 and normal in the remaining 18 patients. There was no difference between the two groups for age, duration of DRBAs treatment, UPDRS III, tremor, rigidity, and bradykinesia subscores for upper and lower limbs. Conversely, symmetry of parkinsonian signs and presence bucco-linguo-masticatory dyskinesias were more frequent in individuals with normal tracer binding. Imaging of the dopamine transporter may help to identify subjects with DIP secondary to a loss of dopamine nerve terminals.