[The effects of dopamine on regional cerebral blood flow in patients with Parkinson's disease before and after L-dopa--measurement by Xe-enhanced CT].

Regional cerebral blood flow (rCBF) was measured using the stable xenon enhanced CT method in previously untreated 13 patients with Parkinson's disease to evaluate CBF abnormality related to dysfunction of the nigrostriatal dopaminergic neurons. The patients comprised 5 men, 8 women with Hoehn-Yahr stage II-III. Age at onset ranged from 51 to 73 years (mean +/- SD, 61.8 +/- 8.9) and the duration of illness ranged from 1 to 96 months (15.1 +/- 24.1 months). In this series, there was no clinical evidence of hypertension, diabetes mellitus and cognitive impairment. rCBF was measured during 4-5-minutes inhalation of 33% stable xenon gas-67% oxygen. The first measurement of rCBF was performed in all of the patients before L-dopa treatment. After initiation of L-dopa treatment (333.3 +/- 47.1 mg/day), the second measurement was carried out in 6 patients (1 man and 5 women) who had shown symptomatic improvement. The interval between both measurements was 57.7 +/- 16.9 days. The following results were obtained. 1) No significant CBF asymmetry was noted in any of the striatum, pallidum, thalamus, cerebrum, cerebellum and frontal lobe in untreated patients with Parkinson's disease. 2) After L-dopa treatment, rCBF was significantly increased only in the striatum as compared with the pretreatment level (51.9 +/- 9.3-->63.1 +/- 9.9 ml/100 g/min, p < 0.01). 3) This increase was significantly greater on the more severely affected side (contralateral to the predominantly symptomatic limb) (p < 0.05). These results suggest that the increase of rCBF in the striatum is closely related to functional improvement of the nigrostriatal dopaminergic neurons.