[Cerebrovascular circulation from a clinical view. Historical review, physiology, pathophysiology, diagnostic and...

Strokes have been known since ancient times. Today, stroke is the second most frequent cause of death and the most frequent cause of invalidity. In about 80% of cases, stroke is caused by cerebral ischemia and in about 20% by intracerebral hemorrhage, subarachnoidal hemorrhage, venous thrombosis and other cerebrovascular diseases. The brain is one of the most richly perfused tissues and depends fundamentally on the supply of oxygen and glucose. In order to assure adequate cerebral blood flow, the brain is capable of autoregulation through the interaction of diverse autoregulatory mechanisms (myogenic, neurogenic and metabolic factors, blood viscosity, renin-angiotensin-system and endothelium). Reduction of cerebral blood flow below the threshold of about 25 ml/100 g x min leads to an impairment of the functional metabolism and later to impairment of the structural metabolism. Pathophysiologically, a large number of isolated pathobiochemical processes (loss of energy, lactate acidosis, excitating amino acid release, ion balance disorders, calcium overload, free radical release, etc.) start to interfere with each other. Delayed edema and inflammation lead to secondary brain damage. Apoptosis is probably induced by ischemia and can cause secondary deterioration. The basic principles in the treatment of ischemia are firstly the rapid restoration of cerebral blood flow (lysis, carotid endarterectomy) and secondly--following infarction--a limitation of brain damage (preservation of ischemic but not necrotic brain tissue, prevention of secondary complications). Stroke treatment requires profound diagnostic and therapeutic expertise and interdisciplinary cooperation of neuroradiologists, neurosurgeons, vascular surgeons and cardiologists. Stroke can best be managed in special "stroke units", which have now been established in nearly all parts of Germany. Beside acute management of stroke and neurological rehabilitative treatment, emphasis has to be laid on primary (public information, education, treatment of risk factors) and secondary prophylaxis (treatment with antiaggregants, anticoagulants, a. o.).