Relationship between oedema, blood pressure, and blood flow following local brain injury

Vasogenic brain oedema is a concomitant of a wide variety of central nervous system lesions that have in common a disturbance of the blood-brain barrier permeability. Although it is well established that the formation and spread of this extracellular type of oedema is influenced directly by variations of systemic arterial pressure, the consequences of these events on local cerebral blood flow are not known. In the current experiments, vasogenic brain oedema was produced in rats by cold-injury lesions, and local cerebral blood flow measurements were made using a technique of 14C-antipyrine quantitative autoradiography under pharmacologically controlled conditions of hypertension, hypotension, and normotension. Evidence is presented that the formation and spread of vasogenic brain oedema is accompanied by the development of a congruent zone of decreased local cerebral blood flow, and that the magnitude of this field of oedema/ischaemia is a direct function of systemic arterial pressure. These findings may have important clinical implications.