In most countries of the Western world, stroke is the commonest disease of the central nervous system to warrant admission of a patient to hospital. Although fatality rates and, in some studies, even incidence rates have been reported to decrease over the last few decades (Mas & Zuber 1991), stroke remains one of the major challenges of medicine at the end of the second millenium, because of its frequency, mortality, and the risk of disabling sequelae in survivors.

Definitions

Stroke is a focal neurological deficit of acute onset of a presumed vascular origin. This definition implies a clinical event, with a focal dysfunction (usually a persisting lesion) of the central nervous system (usually the brain), which is likely (though often unproven) to be secondary to a primary disease involving the vessels and circulation. Stroke can be ischaemic or haemorrhagic. Pure subarachnoid haemorrhage is usually considered separately, because of the initial lack of focal cerebral involvement.Ischaemic stroke is the most common type (85%-90%) (Oxfordshire Community Stroke Project 1983; Bogousslavsky et al. 1988c). It corresponds to transient or persisting interruption or decrease of blood flow in a focal area of the brain, usually in a partial or complete territory of a cerebral artery. The cause is usually an occlusion of the corresponding artery, but rather from embolism than from in situ disease, except in the very small branches which perforate the parenchyma (50–300 µm in diameter) (Fisher 1965).The lack of local (global cerebral ischaemia is not stroke) blood supply triggers a bioelectric and metabolic cascade which ultimately results in tissue necrosis (cerebral infarct), if blood flow is not restored during the very first minutes or hours