Regional cerebral blood flow in hemiparkinsonian patients. Emission computerized tomography of inhaled 133Xenon before and after levodopa

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Abstract
Regional and mean cerebral blood flow (rCBF, CBF) were measured by tomography of inhaled 133Xe in 18 hemiparkinsonian patients before and after levodopa (L-dopa). Baseline mean CBF was 55 ml/(100 g .times. min) after an L-dopa-free interval of at least 10 h (range 10-13) and remained unchanged at 56.1 ml/(100 g .times. min) after optimal clinical improvement was achieved by L-dopa. However, L-dopa reduced rCBF significantly (P < 0.05) in the striatum contralateral to the symptomatic limbs. In patients with adverse reactions such as hyperkinesias and on/off symptoms, flow tended to increase bilaterally in striatum and often markedly in midline structures anatomically related to globus pallidus and thalamus. Compared with a normal population, the subcortical rCBF distribution was asymmetrical with a reduced flow (-18%) in the striatum contralateral to the symptomatic limbs and in midline structures anatomically related to globus pallidus and thalamus (-12%). Cortical CBF was inverse related to the duration of Parkinson''s disease (P < 0.05), probably reflecting an increasing mental deterioration with time.