There are about 25.7 million stroke survivors worldwide. Ischaemic stroke remains the most common type of stroke. Numerous modifiable risk factors have been identified, including behaviors such as cigarette smoking and sedentary lifestyle and treatable medical comorbidities such as hypertension, hyperlipidemia and atrial fibrillation. Once considered irreversible, acute ischaemic stroke is now amenable to acute medical and endovascular therapies to reduce infarct volume. Many advances are expected in the years to come, particularly in the areas of prevention and recovery.Stroke is an ancient human affliction that takes and alters life. Fortunately, great progress has been made in the prevention and treatment of ischaemic stroke, the most common type of stroke.
EpidemiologyThe Global Burden of Diseases 2013 study showed that age-standardized incidence, mortality, prevalence, disability-adjusted life years and years lived with disability had declined although the absolute number of individuals affected by stroke increased from 1990 to 2013 [1]. There were nearly 25.7 million survivors of stroke (71% with ischaemic stroke) and 6.5 million deaths from stroke (51% died from ischaemic stroke) [2]. Amongst younger adults aged 20-64 years, there were an estimated 7.2 million cases of ischaemic stroke [3]. Men are at higher risk of ischaemic stroke than women (133 vs. 99 per 100 000) [4].Most of the variation in risk of stroke for a given age and sex can be attributed to known risk factors. INTERSTROKE was an international caseÀcontrol study involving in 32 countries in Asia, America, Europe, Australia, the Middle East and Africa [5]. Cases were patients with recent first stroke (within 5 days of symptom onset and 72 h of hospital admission). Controls were hospital-based or community-based individuals with no history of stroke matched one-to-one for age and sex. A total of 26 919 participants were recruited between 2007 and 2015. The following 10 potentially modifiable risk factors were found to be associated with stroke: hypertension, regular physical activity, apolipoprotein (Apo)B/ApoA1 ratio, diet, waist-to-hip ratio, psychosocial factors, cardiac causes, current smoking, alcohol consumption and diabetes mellitus were all associated with stroke. Collectively, these risk factors accounted for 90.7% of the population-attributable risk (PAR) for all stroke worldwide (91.5% for ischaemic stroke).
EtiologyIschaemic stroke is caused by abrupt and sustained reduction in regional cerebral blood flow (CBF) leading to cell death. Within hours, patients often have a central zone of irreversibly damaged tissue destined to die known as the infarct core and a surrounding zone of damaged tissue that may recover with abrupt restoration of CBF known as penumbra. Intensive efforts are under way to develop a practical and reliable way of assessing core and penumbra. With magnetic resonance (MR) imaging, areas with diffusionÀperfusion mismatch (i.e. diffusion-weighted imaging lesion within a larger perfusion-weighted