[Pharmacologic modification of the circulation in the brain]

Hemispheric and regional cerebral blood flow were measured in 448 patients before and after application of various drugs. Of the tested substances, only a few affected hCBF: ephedrine-xanthines decreased hCBF, and midodrine, proxazole, vincamine, hexobendine, extract of ginkgo biloba, dextran, dextran-sorbitol, carboanhydrase inhibitor, and ouabain incresaed hCBF. In the rCBF maps different reaction patterns of regional flow were observed which were statistically tested by regression analysis. Homogeneous responses were seen as diffuse increases or decreases of rCBF. Heterogeneous responses occurred when perfusion of pathologic and normal areas reacted differently. An increase in rCBF in well-perfused areas with a shunt of blood from poorly supplied areas (intracerebral steal) was observed only with central vasodilators during the first days after an attack. Inverse cerebral steal phenomena with improvement of perfusion in the focus and decrease of flow in the surrounding brain may be elicited by different mechanisms. The effectiveness of drugs on cerebral circulation can be tested by measuring rCBF, but their therapeutic value for the treatment of patients with cerebrovascular disease must be shown in controlled clinical trials.