Pathophysiology of extracranial cerebral arterial stenosis--a critical review.

THE PURPOSE OF THIS REVIEW IS to discuss the phenomenon of stenosis in extracranial cerebral arteries, its effects on normal blood flow patterns and the biological and clinical implications for the extracranial cerebral circulation. Stenosis, generally defined as a narrowing or constriction, is of particular interest because of its potential to decrease blood flow. Stenosis of the extracranial cerebral vessels is of clinical concern because the disordered flow patterns which can result may lead to exacerbation of the stenosis itself or contribute to problems in the distal vasculature. Transient cerebral ischemia, stroke, thromboembolism and post stenotic dilatation have all been reported in association with stenosis. In this paper an introduction to the principles of normal blood flow is provided, followed by a discussion of the pathophysiological effects of stenosis. The final section considers ideas relevant to clinical aspects of extracranial cerebral arterial stenosis.