Classification and mechanisms of cerebrovascular disease.

Infarction remains the cause of stroke in 75 to 80% of patients. The leading cause is embolism from one of several sources, although the source of the particles is often not discovered despite prolonged search. Brain infarction associated with high-grade stenosis or occlusion of major arteries may also be caused by local embolism but in one-third of patients, the process of infarction seems attributable to perfusion failure, with a more leisurely evolution of the syndrome than that typical of embolism. Lacunar disease accounts for roughly 20% of strokes.