DefinitionDefinition of stroke, devised by the
World Health Organization in the 1970s, is a
"neurological deficit of cerebrovascular cause that persists beyond 24 hours or is interrupted by death within 24 hours". This definition was supposed to reflect the reversibility of tissue damage and was devised for the purpose, with the time frame of 24 hours being chosen arbitrarily. The 24-hour limit divides stroke from
transient ischemic attack, which is a related syndrome of stroke symptoms that resolve completely within 24 hours.
A stroke is a medical emergency. Strokes happen when blood flow to your brain stops. Within minutes, brain cells begin to die. There are two kinds of stroke. The more common kind, called ischemic stroke, is caused by a blood clot that blocks or plugs a blood vessel in the brain. The other kind, called hemorrhagic stroke, is caused by a blood vessel that breaks and bleeds into the brain. "Mini-strokes" or transient ischemic attacks (TIAs), occur when the blood supply to the brain is briefly interrupted.
Strokes can be classified into two major categories:
ischemic and hemorrhagicIschemic strokeIn an ischemic stroke, blood supply to part of the brain is decreased, leading to dysfunction and necrosis of the brain tissue in that area. There are
four reasons why this might happen:
thrombosis (obstruction of a blood vessel by a blood clot forming locally),
embolism (idem due to a embolus from elsewhere in the body, see below),
systemic hypoperfusion (general decrease in blood supply, e.g. in shock) and
venous thrombosis. Stroke without an obvious explanation is termed "cryptogenic" (of unknown origin).
Hemorrhagic strokeIntracranial hemorrhage is
the accumulation of blood anywhere within the skull vault. A distinction is made between intra-axial hemorrhage (blood inside the brain) and extra-axial hemorrhage (blood inside the skull but outside the brain). Intra-axial hemorrhage is due to intraparenchymal hemorrhage or intraventricular hemorrhage (blood in the ventricular system). The main types of extra-axial hemorrhage are
epidural hematoma (bleeding between the dura mater and the skull),
subdural hematoma (in the subdural space) and
subarachnoid hemorrhage (between the arachnoid mater and pia mater). Most of the hemorrhagic stroke syndromes have specific symptoms (e.g. headache, previous head injury).
Intracerebral hemorrhage (ICH) is bleeding directly into the brain tissue, forming a gradually enlarging hematoma (pooling of blood). It generally occurs in small arteries or arterioles and is commonly
due to hypertension, trauma, bleeding disorders, amyloid angiopathy, illicit drug use (e.g. amphetamines or cocaine), and vascular malformations. The hematoma enlarges until pressure from surrounding tissue limits its growth, or until it decompresses by emptying into the ventricular system, CSF or the pial surface. A third of intracerebral bleed is into the brain's ventricles. ICH has a mortality rate of 44 percent after 30 days, higher than ischemic stroke or even the very deadly subarachnoid hemorrhage.
Stroke is occasionally treated with thrombolysis ("clot-buster"), but usually with supportive care (physiotherapy and occupational therapy) and secondary prevention with antiplatelet drugs (aspirin and often dipyridamole), blood pressure control, statins and anticoagulation (in selected patients)Symptoms of stroke * Sudden numbness or weakness of the face, arm or leg (especially on one side of the body)* Sudden confusion, trouble speaking or understanding speech* Sudden trouble seeing in one or both eyes* Sudden trouble walking, dizziness, loss of balance or coordination* Sudden severe headache with no known causeIf you have any of these symptoms, you must get to a hospital quickly to begin treatment.PreventionsBecause stroke may indicate underlying atherosclerosis, it is important to determine the patient's risk for other cardiovascular diseases such as coronary heart disease. Conversely, aspirin prevents against first stroke in patients who have suffered a myocardial infarction.The most important
modifiable risk factors for stroke are
high blood pressure and atrial fibrillation. Other modifiable risk factors include
high blood cholesterol levels, diabetes, cigarette smoking (active and passive), heavy alcohol consumption and drug use, lack of physical activity, obesity and unhealthy diet. Alcohol use could predispose to ischemic stroke, and intracerebral and subarachnoid hemorrhage via multiple mechanisms (for example via hypertension, atrial fibrillation, rebound thrombocytosis and platelet aggregation and clotting disturbances). The drugs most commonly associated with stroke are
cocaine, amphetamines causing hemorrhagic stroke, but also over-the-counter cough and cold drugs containing sympathomimetics.
Source:National Institute of Neurological Disorders and Stroke (http://www.nlm.nih.gov/medlineplus/stroke.html)Wikipedia encyclopedia (http://en.wikipedia.org/wiki/Stroke)
After considering many variable such as age, sex, and smoking habit, the researcher found there is significant connection between some of symptoms of the metabolic syndrome with the arising silent brain infarct. It is reported that the patients that have one component of metabolic syndrome have 1,49 times higher risk to suffer this silent brain infarct, meanwhile the subject with four components of metabolic syndrome have 4,71 times higher risk.
