No abstract

We compared the rCBF changes induced by the execution of a finger-to-thumb opposition motor task in the cerebellar hemispheres of 12 normal subjects, 12 parkinsonian patients whose medication had been withheld for at least 18 h and 16 parkinsonian patients on medication using single photon emission tomography and i.v. 133Xe. The normal subjects and parkinsonian patients on medication exhibited the same pattern of response, with a significant increase in rCBF in the contralateral primary motor cortex and in the supplementary motor areas. No significant rCBF change was detected in the cerebellum of these two groups; this finding was expected since our technique cannot detect cerebellar activation when the motor task is executed at a relatively low rate and small amplitude as it was in this study. The parkinsonian patients off medication exhibited a markedly different pattern of activation characterized by a significant overactivation in the ipsilateral cerebellar hemisphere and a significant underactivation in the supplementary motor areas. These results suggest that parkinsonian patients off medication may try to compensate for their basal ganglia-cortical loop's dysfunction using other motor pathways involving cerebellar relays.

Besides antipsychotics, several drugs can induce parkinsonism. We review spontaneous notifications of drug-induced or -worsened parkinsonism to a French regional pharmacovigilance center between 1993 and 2009. During these 17 years, 20,855 adverse drug reactions have been reported, including 155 (0.7%) cases of drug-induced or -worsened parkinsonism. Most of the notifications have involved aged patients (48% between 60 and 79 years) and females (60%). "Seriousness" was found in 43.9% of cases. Worsening of parkinsonism occurred in 28 patients suffering from idiopathic Parkinson's disease. Sixty-nine percent of drug-induced or -worsened parkinsonism cases were observed during the first 3 months after introduction of the "suspect" drug (involving mainly central dopaminergic antagonists). A second peak (20%) was found 12 months after drug introduction (mainly caused by calcium channel blockers). The most frequently reported parkinsonian symptom was rigidity (78.7%). The three cardinal symptoms were found in 37.4% of notifications. Evolution was favorable (after partial or complete withdrawal of suspect drug[s]) in 88.7% of cases. Among the 261 suspect drugs, most involved central dopaminergic antagonists (49%), followed by antidepressants (8%), calcium channel blockers (5%), peripheral dopaminergic antagonists (5%), and H1 antihistamines (5%). Cases with lithium, valproic acid, amiodarone, anticholinesterases, or trimetazidine were also found. Three notifications were the result of pharmacokinetic interactions. We found that drug-induced or -worsened parkinsonism is an often "serious," but reversible, adverse drug reaction. It occurred more frequently between 60 and 79 years. Rigidity was the most frequently reported symptom. Approximately 50% of drug-induced or -worsened parkinsonism cases spontaneously reported were related to drugs other than antipsychotics. Drug-induced or -worsened parkinsonism can also be explained by pharmacokinetic drug interactions.

We have studied the regional cerebral blood flow (rCBF) changes induced by the execution of a finger-to-thumb opposition motor task in the supplementary and primary motor cortex of two groups of parkinsonian patients on L-dopa medication, the first one without L-dopa induced dyskinesia (n = 23) and the other with moderate peak-dose dyskinesia (n = 15), and of a group of 14 normal subjects. Single photon emission tomography with i.v. 133Xe was used to measure the rCBF changes. The dyskinetic parkinsonian patients exhibited a pattern of response which was markedly different from those of the normal subjects and non-dyskinetic parkinsonian patients, with a significant overactivation in the supplementary motor area and the ipsi- and contralateral primary motor areas. These results are compatible with the hypothesis that an hyperkinetic abnormal involuntary movement, like L-dopa-induced peak dose dyskinesia, is due to a disinhibition of the primary and associated motor cortex secondary to an excessive outflow of the pallidothalamocortical motor loop.