[Epidemiology of cerebral infarction]

The annual incidence of strokes (all types) is estimated to be between two and four per thousand in the 55 to 64 year age-group and reaches about 15 per thousand over the age of 75 years. Population registries and hospital registries show that cerebral infarcts represent about 80% of all strokes and indicate the respective roles of the principal causes. A significant reduction in mortality related stroke in general and cerebral infarction in particular has been observed in many countries over recent decades. Hypertension constitutes the principal risk factor for ischaemic and haemorrhagic stroke. This risk varies by about 40% when the mean diastolic blood pressure varies from 5 to 10 mmHg, even in normotensive subjects. Several studies have demonstrated that treatment of moderate or severe hypertension lowers the incidence of stroke. Smoking, diabetes, chronic alcoholism (> 3 standard glasses per day), hypercholesterolaemia and raised plasma fibrinogen also constitute independent risk factors for cerebral infarction. Of the emboligenic heart diseases, non-valvular atrial fibrillation (80% of all cases of atrial fibrillation) is the most potent risk factor for cerebral infarction: subjects with this disease have a risk of cerebral infarction of approximately 5% per year. The presence of asymptomatic carotid artery stenosis is associated with an annual risk of cerebral infarction generally estimated to be between 1 and 2% which, in reality, increases with the degree of stenosis. Even in the case of tight stenosis, the risk of ipsilateral cerebral infarction remains low (< 3% per year for stenosis > 75%).(ABSTRACT TRUNCATED AT 250 WORDS)