[The pathophysiology of cerebral circulation]

Abstract

Local and generalized decreases in cerebral circulation most frequently cause severe functional and morphological disturbances in the central nervous system. During a generalized cerebral ischemia, the appearance of signs of disturbances in electrical and metabolic functions follows a characteristic course. These changes have been demonstrated in experimental examples. In severe hypoxia with occlusion of cerebral arteries, the changes in energy metabolism and electrical phenomena are similar to those in ischemia. The typical signs of oligemic hypoxia, anoxic and hypoxic hypoxia, anemic hypoxia, venous hypoxia and histotoxic hypoxia are characterized in this review. In energy deficient brain tissue the ionic fluxes across the membranes of nerve cells, as well as across the smooth muscle cell membranes of the cerebral artery walls, are of particular interest. Cations have been investigated frequently and in this report the interactions between ions which participate in the regulation of vessel wall tension are discussed. Finally, the redistribution of blood flow after occlusion of single brain-supplying arteries is described.