Stroke is the third most common cause of death in the West and the most important cause of adult disability (Lancet, 1992; 339:342-4). Among those over 65 it is the second most common cause of death after heart disease.

Stroke is a non specific, collective term for symptoms, such as paralysis, perceptual loss, speech difficulties and visual problems, which are the result of trauma to the brain tissue. Trauma can be caused either by loss of blood supply (infarction), and thus death of the surrounding tissue caused by blockage or occlusion (closure) of a vessel. It can also be caused by cerebral hemorrhage.

In the West, 85 per cent of strokes result from cerebral infarction after arterial occlusion (Lancet, 1992; 339:533-6). Cere bral infarction can be the result of atherosclerosis (narrowing of the arteries) or occlusion caused by cerebral thrombosis (blood clot in the brain). Often the two are present together since the formation of blood clots in the brain can be the result of platelets forming in response to the damaged lining of the blood vessels. Cerebral embolism, where a clot which has formed in another part of the body usually the heart or the deep veins in the legs travels up into the brain, has the same effect.

High blood pressure (hypertension) can cause hemorrhage usually through aneurysm (a local "ballooning" of an artery causing it to burst). The extreme force of blood leaking from an artery damages the delicate brain tissue as well as compressing and impairing the function of adjacent tissues. A similar effect can be produced by water retention (edema) around the brain. The degree of disability after a stroke depends largely on the duration and the site of the trauma.

Over the years research has taken a circular route of proving and disproving the same old theories. As a result, many commentaries come to the same conclusion, namely that in spite of vast amounts of money which have been poured into the study of stroke and related vascular disorders, there is still very little known about this devastating disorder (BMJ, 1995; 311:139-40). Much of the research concerns itself with finding the single most effective prophylaxis (preventative) for primary or secondary strokes, the most popular options being anti coagulants, anti platelets, anti hypertensives, diuretics and surgery. Too often treatment ends up being a combination of any or all of these things.

It is also important to note that "effective" in stroke research generally means "cost effective" and that prevention usually has the aim of reducing the cost of patients requiring hospital admission and treatment for stroke, rather than improving the quality of life for victims of stroke (JAMA, 1995; 274:1839-45).

The "magic bullet" philosophy upon which modern medicine is built does not benefit stroke patients. Perhaps the best example of this can be seen in the wholesale administration of aspirin (an anti platelet) as a treatment for and prophylactic measure against stroke. Aspirin thins the blood as well as having an anti hypertensive effect, so for many physicians it has long seemed a logical way of preventing stroke in patients with constricted blood vessels, those who have suffered heart attacks or those who have experienced transient ischaemic attacks (or TIAs, minor strokes of short duration). The fact that it was cheap, readily available and familiar to patients was also in its favour. Evidence for the use of aspirin in the treatment of stroke has been accumulating for years but was perceived as having been given the definitive thumbs up by the Antiplatelet Trialists' Collaboration (ATC) in a series of articles in 1994 (BMJ, 1994; 308:81-106; BMJ, 1994; 308: 159-68; BMJ, 1994; 308:235-46). These findings echoed many of the group's findings six years before (BMJ, 1988; 296:320-31). Although, on closer inspection the group's findings were more circumspect than many were willing to acknowledge at the time, aspirin quickly became hailed as the conquering hero of stroke treatment and has since been prescribed widely (almost recklessly), throughout the world regardless of patient's individual "risk" factors.