A stroke (or cerebrovascular accident, CVA) is much like what a heart attack is to the heart, but to the brain. A stroke involves the sudden interruption of blood flow and oxygen to areas in the brain and can cause brain damage and loss of function. Stroke develops suddenly, usually in a matter of minutes, and causes symptoms such as paralysis, numbness or weakness often affecting one side of the body, confusion, dizziness, speech problems, and loss of vision. How a stroke patient is affected depends on where the stroke occurs in the brain and how much the brain is damaged.
There are two main types of strokes: ischemic and hemorrhagic. Ischemic strokes are by far the more common type, and occur when a blood clot or plaque (protein, cholesterol, and material) deposit blocks an artery supplying blood to the brain. A hemorrhagic stroke occurs when an artery in the brain bursts, causing blood to flow into the surrounding tissue. The mortality rate is higher for hemorrhagic stroke than for ischemic stroke, with most deaths occurring within the first 48 hours of the event.
A transient ischemic attack (TIA) is a type of stroke that usually lasts only 10 - 20 minutes. TIAs are sometimes considered to be "mini-strokes." While TIAs cause no long-term damage, having a TIA puts an individual at increased risk of acute stroke. Symptoms of TIAs may go unnoticed, and may be confused with other conditions such as epilepsy, migraines, or diabetes.
Stroke is a medical emergency. Prompt treatment of a stroke could be the difference between life and death. Early treatment can also minimize damage to the brain and potential disability.
The National Stroke Association reports that in the United States, stroke is a leading cause of adult disability and the third-leading cause of death. Only heart disease and cancer cause more deaths annually.
Men are 1.25 times more likely to suffer from strokes than women, yet 60% of deaths from stroke occur in women.
Eighty percent of strokes are preventable, which would save approximately 600,000 Americans annually.
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types of stroke
Ischemic stroke: About 80% of strokes are ischemic strokes. Blood clots or other particles such as cholesterol may block arteries to the brain and cause severely reduced blood flow (ischemia). This deprives the brain cells of necessary oxygen and nutrients, and may lead to cell death within minutes. The most common ischemic strokes include thrombotic stroke and embolic stroke.
Thrombotic stroke: This type of stroke occurs when a blood clot (thrombus) forms in one of the arteries that supply blood to the brain. Areas damaged by atherosclerosis (hardening of the arteries) are highly susceptible to developing a blood clot. Arteries in the brain or in the neck (carotid arteries) that carry blood to the brain are susceptible. An ischemic stroke may also be caused by plaque (deposits of fat, protein, and other particles in the blood) that narrows or completely clogs an artery. This narrowing is called stenosis.
Embolic stroke: An embolic stroke occurs when a blood clot or other particle forms in a blood vessel away from the brain (such as the heart) and travels through the blood to eventually lodge in narrower brain arteries (called an embolus). Emboli may often be caused by irregular beating in the heart's two upper chambers (atrial fibrillation). This abnormal heart rhythm can lead to stagnant (sluggish) blood flow and the formation of blood clots.
Hemorrhagic stroke: Hemorrhage means bleeding. Hemorrhagic stroke occurs when a blood vessel in the brain leaks or breaks open (ruptures). Hemorrhages can result from a number of conditions that affect the blood vessels, including uncontrolled high blood pressure (hypertension) and weak spots in the blood vessel walls (aneurysms). A less common cause of hemorrhage is the rupture of an arteriovenous malformation (AVM), or a malformed tangle of thin-walled blood vessels present at birth. There are two types of hemorrhagic stroke including intracerebral hemorrhage and subarachnoid hemorrhage.
Intracerebral hemorrhage: In this type of stroke, a blood vessel in the brain bursts and spills into the surrounding brain tissue, damaging cells. Brain cells beyond the leak are deprived of oxygen and are also damaged. High blood pressure is the most common cause of this type of hemorrhagic stroke, causing small arteries inside the brain to become fragile and susceptible to tearing and rupture.
Subarachnoid hemorrhage: In this type of stroke, bleeding starts in a large artery on or near the membrane surrounding the brain and spills into the space between the surface of the brain and skull. A subarachnoid hemorrhage is often signaled by a sudden, severe "thunderclap" headache. This type of stroke is commonly caused by the rupture of an aneurysm, which can develop with age or result from a genetic predisposition. After a subarachnoid hemorrhage, vessels may go into vasospasm, in which arteries near the hemorrhage widen and narrow erratically, causing brain cell damage by further restricting or blocking blood flow to portions of the brain.