TREMOR AND VOLUNTARY REPETITIVE MOVEMENT IN PARKINSONS-DISEASE - COMPARISON BEFORE AND AFTER L-DOPA WITH POSITRON EMISSION TOMOGRAPHY

Brain regions involved in tremor and voluntary movement were compared in seven subjects with hemiparkinsonian tremor using positron emission tomography and the [O-15]water bolus activation method. Repeated meas urements of the regional cerebral blood flow were performed both befor e 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 m easured in regions of interest with anatomical boundaries that were de fined for each subject by means of a three-dimensional reconstruction of mag magnetic resonance imaging data. Taking the rest after L-dopa a s a control condition, NrCBF increased during tremor in a network of r egions 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 p airs), and the cerebellar vermis (8.64 +/- 9.9%, P = 0.07, n = 12). Du ring voluntary repetitive movement of the hand contralateral to tremor compared with rest after L-dopa, the same patients activated the prec entral (8.25 +/- 2.6%, P = 0.0006) and postcentral regions contralater al to movement (8.43 +/- 3.7%, P = 0.002), and the cerebellar cortex ( 3.49 +/- 2.1%, P = 0.03), precentral (3.58 +/- 3.1%, P = 0.04), and pa racentral (4.03 +/- 3.6%, P = 0.04) regions ipsilateral to movement. T he cerebellar vermis was activated (8.15 +/- 5.6%, P = 0.02, n = 8) as well as the SMA, but not significantly at the 0.05 level (5.16 +/- 5% , P = 0.08, n = 5). These results confirm the similarities of brain st ructures involved in parkinsonian tremor and voluntary movement and pr ovide an anatomofunctional substrate for their clinical interactions.