A STROKE that occurs when the ﬂow of blood to a part of the brain is interrupted by a partial or complete THROMBOSIS of the supplying artery or ARTERIES, or by a clot of blood that has detached itself from elsewhere in the circulatory system – for instance, a deep vein thrombosis (DVT) – and blocked a cerebral artery. Stroke is the second most common cause of death worldwide. Its treatment is diﬃcult and prevention is best targeted at those who are at the highest absolute risk of stroke, because such people are likely to derive the greatest beneﬁt. They generally have a history of occlusive vascular diseases such as previous ischaemic stroke or a transient ischaemic attack (TIA), coronary heart disease (see HEART, DISEASES OF) or PERIPHERAL VASCULAR DISEASE. In the UK strokes aﬀect about 200 people per 100,000 population annually, with the incidence rising sharply after the age of 55. At the age of 70 the incidence is around 15 people per 1,000 of population; at 80 the ﬁgure is double that.
About 80 per cent of patients survive an acute stroke and they are at risk of a further episode within a few weeks and months; about 10 per cent in the ﬁrst year and 5 per cent a year after that. HYPERTENSION, smoking, HYPERLIPIDAEMIA and raised concentration of blood sugar, along with OBESITY, are signiﬁcant pointers to further strokes and preventive steps to reduce these factors are worthwhile, although the reduction in risk is hard to assess. Even so, the aﬀected person should stop smoking, greatly reduce alcohol intake, check for and have treated diabetes, reduce weight and exercise regularly. In any case, a diet rich in fresh fruit and vegetables and low in fat and salt, exercise and the avoidance of smoking may reduce the risk of having a ﬁrst stroke.
The evidence is inconclusive that patients with ischaemic stroke should be treated with antihypertensives. Furthermore, neither the starting blood pressure nor the best drug regimen or its starting time are generally agreed. Studies on the most eﬀective methods of preventing and treating stroke are continuing; meanwhile available evidence suggests that an active approach to prevention of primary and secondary hypertension will beneﬁt patients and usually be cost-eﬀective.