[Epidemiology of strokes. Impact on the treatment decision].

The development of several population stroke registries has improved our knowledge of the epidemiology of strokes, their natural history, and their trends over time and place. In Europe, stroke incidence decreases from east to west and from north to south. Incidence and mortality have also been decreasing regularly over time. The diagnostic tools created with the arrival of computed tomography (CT), magnetic resonance imaging (MRI), and other forms of vascular and cardiac imaging have improved the identification of risk factors for stroke according to its mechanism--hemorrhagic or ischemic--and according to the subtype of ischemic stroke. Hypertension is the leading risk factor for both ischemic and hemorrhagic strokes. New independent stroke risk factors have been confirmed, including elevated cholesterol and homocysteine levels. The regular decline of the incidence of some types of stroke and of mortality is partly due to the positive effects of prevention and confirms the usefulness of screening and early treatment of stroke risk factors. Development of new treatments during the acute phase and in the field of primary and secondary stroke prevention (such as statins) is necessary to improve prognosis, which remains too serious, especially in women.