Stroke Explained

by CDC

A stroke occurs either when the blood supply to part of the brain is blocked or when a blood vessel in the brain bursts, causing damage to a part of the brain. A stroke is also sometimes called a brain attack.

Stroke is the third leading cause of death in the United States. Among survivors, stroke can cause significant disability including paralysis as well as speech and emotional problems. New treatments are available that can reduce the damage caused by a stroke for some victims. But these treatments need to be given soon after the symptoms start.

Knowing the symptoms of stroke, calling 911 right away, and getting to a hospital are crucial to the most beneficial outcomes after having a stroke. The best treatment is to try to prevent a stroke by taking steps to lower your risk for stroke.

Learn more about the symptoms of stroke and how to reduce the risk of stroke.

Types of Stroke

Ischemic Stroke

An ischemic stroke occurs when an artery that supplies blood and oxygen to the brain becomes blocked. Most strokes are of this type. Blood clots are the most common cause of artery blockage. Ischemic strokes can also be caused by a narrowing of the arteries (called stenosis). The most common condition that causes stenosis is atherosclerosis. In atherosclerosis, plaque (a mixture of fatty substances including cholesterol and other lipids) and blood clots build up inside the artery walls, causing thickening, hardening, and loss of elasticity. These lead to decreased blood flow.

Hemorrhagic Stroke

A hemorrhagic stroke occurs when an artery in the brain bursts. Hemorrhage can occur in several ways. One cause is an aneurysm, a weak or thin spot on an artery wall that can expand like a balloon. The thin walls of the stretched artery can rupture or break. Hemorrhage also occurs when arterial walls lose their elasticity and become brittle and thin. They can then crack and bleed. This can happen with atherosclerosis. High blood pressure increases the risk of a hemorrhagic stroke.

There are two main types of hemorrhagic stroke. An intracerebral hemorrhage occurs when a blood vessel in the brain leaks blood into the brain itself. A subarachnoid hemorrhage is bleeding under the outer membranes of the brain and into the thin fluid-filled space that surrounds the brain.

Transient Ischemic Attacks

A transient ischemic attack (TIA) is sometimes called a mini-stroke. It starts just like a stroke but then clears up within 24 hours, leaving no apparent symptoms or deficits. A TIA is a warning that the person is at risk for a more serious stroke. Having other risk factors increases a person's chances of a recurrent stroke if they have had a TIA. For most TIAs the symptoms go away within an hour. However, there is no way to tell whether symptoms will be a TIA or a more serious stroke that can lead to death or disability. The sudden onset of the symptoms of a stroke should signal an emergency. Patients and witnesses should not wait to see if the symptoms go away.

Stroke Facts

Stroke is the third leading cause of death in the United States. Over 160,000 people die each year from stroke in the United States. Stroke is a leading cause of serious long-term disability. About 700,000 strokes occur in the United States each year. About 500,000 of these are first or new strokes. About 200,000 occur in people who have already had a stroke before. Nearly three-quarters of all strokes occur in people over the age of 65. The risk of having a stroke more than doubles each decade after the age of 55. Strokes can-and do-occur at ANY age. Nearly one quarter of strokes occur in people under the age of 65. Stroke death rates are higher for African Americans than for whites, even at younger ages. According to the American Heart Association, stroke cost almost $57 billion in both direct and indirect costs in 2005. It has been noted for several decades that the southeastern United States has the highest stroke mortality rates in the country. It is not completely clear what facto

Risk Factors

Some conditions as well as some lifestyle factors can put people at a higher risk for stroke. The most important risk factors for stroke are high blood pressure, heart disease, diabetes, and cigarette smoking. Persons who have already had a stroke need to control the risk factors in order to lower their risk of having another stroke. All persons can take steps to lower their risk for stroke.

High Blood Pressure

High blood pressure, or hypertension, is a major risk factor for stroke. It is a condition where the pressure of the blood in the arteries is too high. There are often no symptoms to signal high blood pressure. About 60 million people in the United States have high blood pressure. Lowering blood pressure can lower the risk of stroke. Medicines to lower blood pressure can decrease the risk of stroke among those with high blood pressure.

About the Author

www.cdc.gov
The Centers for Disease Control and Prevention (CDC) is one of the 13 major operating components of the Department of Health and Human Services (HHS), which is the principal agency in the United States government for protecting the health and safety of all Americans and for providing essential human services, especially for those people who are least able to help themselves.