In order to provide a pathogenetically oriented differentiation of brain infarctions on the basis of CT-morphological criteria, the CTs of 422 patients with visible brain infarctions were analysed. All of the supratentorial lesions were classified according to topographical features and were associated with the underlying cardio-vascular and other general diseases. This concept lead to a typology of brain infarctions which allowed for a differentiation of ischaemic lesions due to cerebral microangiopathy on the one hand (i.e. lacunar infarctions, subcortical arteriosclerotic encephalopathy), and lesions due to cerebral macroangiopathy on the other. The latter were hemodynamically induced terminal supply area infarctions and watershed infarctions or territorial infarctions due to thromboembolism. A third group of symmetrical subcortical lesions were associated with hypoxia. The frequencies of cerebral lesions within the whole cohort were as follows: 34% cerebral microangiopathy, 45% macroangiopathy, 1% generalised hypoxia, 10% miscellaneous lesions and 10% non-classifiable infarctions. Stenosing lesions of the extracranial brain supplying arteries were found in 22% of the microangiopathy group but in 71% of the macroangiopathy group. Patients with territorial infarctions presented with embolising extracranial vascular lesions in 42% and with embolising heart disease in 21% of the cases. Local thrombosis of the intracranial large arteries was a rare event. Hypoxia occurred due to haemorrhagic shock, carbon monoxide poisoning, air embolism and strangulation. The following conclusions were drawn: In patients with cerebral microangiopathy any procedures aimed at the diagnosis and therapy of major vessel disease are not useful. Therapy should follow the principles of internal medicine. If haemodynamically induced infarctions are present, the clinician's primary task is to look for high grade extracranial vessel lesions. Recanalizing techniques (endarterectomy and ECIC-bypass) are the main therapeutical strategies. In territorial infarctions the embolising extracranial vessel lesions may be haemodynamically non-significant. An intra-arterial source of emboli should be removed by the vascular surgeon. In younger patients, however, and in patients with normal Doppler findings and/or multiple territorial infarctions, a cardiac source of emboli is highly probable and its diagnosis should be pursued consistently. Bilateral symmetrical ganglionic infarctions are indicative of hypoxia and help to exlude other causes of the severe neurological disturbances associated with this condition.(ABSTRACT TRUNCATED AT 400 WORDS)
