Exp Brain Res (1996) 107:453~62 9 Springer-Verlag 1996 Hugues Duffau 9 Nathalie Tzourio Dominique Caparros-Lefebvre 9 Fabrice Parker Bernard Mazoyer Tremor and voluntary repetitive movement in Parkinson's disease: comparison before and after L-dopa with positron emission tomography Received: 17 July 1994 /Accepted: 28 August 1995 Abstract Brain regions involved in tremor and volun- tary movement were compared in seven subjects with hemiparkinsonian tremor using positron emission to- mography and the [1SO]water bolus activation method. Repeated measurements of the regional cerebral blood flow were performed both before and after tremor arrest induced by administration of L-dopa as well as during voluntary repetitive movements of the hand contralateral to tremor side. The normalized regional cerebral blood flow (NrCBF) was measured in regions of interest with anatomical boundaries that were defined for each subject by means of a three-dimensional reconstruction of mag- netic resonance imaging data. Taking the rest after L- dopa as a control condition, NrCBF increased during tremor in a network of regions including the precentral (mean_+SD 5.36_+4.6%, P=0.006) and paracentral (6.11_+6%, P--0.01) gyri contralateral to tremor side, the supplementary motor area (SMA; 4.03_+4%, P=0.02, n=8 pairs), and the cerebellar vermis (8.64_+9.9%, P--0.01, n=12). During voluntary repetitive movement of the hand contralateral to tremor compared with rest after L- dopa, the same patients activated the precentral (8.25_+2.6%, P=0.0006) and postcentral regions contra- lateral to movement (8.43_+3.7%, P--0.002), and the cere- bellar cortex (3.49_+2.1%, P=0.03), precentral (3.58_+3.1%, P=0.04), and paracentral (4.03_+3.6%, P=0.04) regions ipsilateral to movement. The cerebellar vermis was acti- vated (8.15_+5.6%, P=0.02, n=8) as well as the SMA, but H. Duffau. N. Tzourio (~) - B. Mazoyer Groupe d'Imagerie Neurofonctionnelle, Service Hospitalier Fr6d6ric Joliot, DRM-CEA, F-91406 Orsay Cedex, France H. Duffau 9 N. Tzourio 9 B. Mazoyer Facult6 de M6decine Xavier Bichat, Universit~ Paris 7 Denis Diderot, F-75018 Paris, France F. Parker Service de Neurochirurgie, C.H.U. de Bic~tre, F-94274 Le Kremlin Bic~tre, France D. Caparros-Lefebvre Service de Neurologie, C.H.U. de Lille, H6pital B, F-59037 Lille Cedex, France not significantly at the 0.05 level (5.16+5%, P=0.08, n=5). These results confirm the similarities of brain structures involved in parkinsonian tremor and voluntary movement and provide an anatomofunctional substrate for their clinical interactions. Key words Parkinsonian tremor 9 Positron emission tomography 9 Regional cerebral blood flow - Voluntary movement 9 Cerebellum 9 Supplementary motor area 9 L-Dopa Introduction Interactions between tremor and voluntary movement in the parkinsonian patient are an often referred to notion in literature, although the basis of this relationship is not still clearly understood. On the one hand, it is a well- known clinical fact that the execution of a voluntary movement will result in the disappearance of the ipsilat- eral parkinsonian resting tremor (PRT), while the same movement will, contrarily, increase the PRT on the con- tralateral side (Cambier et al. 1994). On the other hand, it has been proved that the parkinsonian tremor can cause an acceleration of repetitive voluntary movements, the maximum frequency of the PRT being also the upper limit of frequency of these movements (Logigian et al. 1991). Using positron emission tomography (PET) and the [~50]water brain activation paradigm, we previously studied PRT in parkinsonian patients bearing thalamic stimulators. Normalized regional cerebral blood flow (NrCBF) was compared during PRT and after PRT was stopped by thalamic electrical stimulation. NrCBF in- creases were observed during PRT in the precentral, postcentral, and paracentral gyri of the hemisphere con- tralateral to tremor side, as well as in the supplementary motor area (SMA), and bilaterally in the cerebellum. These results led us to postulate the existence of a com- mon network of cerebral areas involved in tremor and voluntary repetitive movements and to consider the PRT