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Stroke

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Figure A shows the location of the right carotid artery in the head and neck. Figure B shows the inside of a normal carotid artery that has normal blood flow. Figure C show the inside of a carotid artery that has plaque buildup and reduced blood flow.

A stroke, sometimes called a brain attack, occurs when the blood supply to part of the brain is suddenly interrupted or when a blood vessel in the brain bursts, spilling blood into the spaces surrounding brain cells. Brain cells die when they no longer receive oxygen and nutrients from the blood or there is sudden bleeding into or around the brain.

The symptoms of a stroke include sudden numbness or weakness, especially on one side of the body; sudden confusion or trouble speaking or understanding speech; sudden trouble seeing in one or both eyes; sudden trouble with walking, dizziness, or loss of balance or coordination; or sudden severe headache with no known cause. There are two forms of stroke: ischemic - blockage of a blood vessel supplying the brain, and hemorrhagic - bleeding into or around the brain.[1]

Stroke can cause death or significant disability, such as paralysis, speech difficulties, and emotional problems. Some new treatments can reduce stroke damage if patients get medical care soon after symptoms begin. When a stroke happens, it is important to recognize the symptoms, and get to a hospital quickly. Stroke is the third leading cause of death in the United States. About 137,000 Americans die of stroke every year.[2]

Contents

Types

Stroke types.png

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.[3]

Ischemic Stroke: About 85% of all strokes are ischemic, in which blood flow to the brain is blocked by blood clots or fatty deposits called plaque in blood vessel linings.[4]

Hemorrhagic Stroke: A hemorrhagic stroke occurs when a blood vessel bursts in the brain. Blood accumulates and compresses the surrounding brain tissue. There are two types of hemorrhagic strokes.

  • Intracerebral hemorrhage is the most common type of hemorrhagic stroke. It occurs when an artery in the brain bursts, flooding the surrounding tissue with blood.
  • Subarachnoid hemorrhage is bleeding in the area between the brain and the thin tissues that cover it.[4]

Transient ischemic attack (TIA) is a "warning stroke" or a "mini-stroke" that results in no lasting damage. Recognizing and treating TIAs immediately can reduce your risk of a major stroke.[4]

Symptoms

Symptoms of stroke are:* 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 cause

If you have any of these symptoms, you must get to a hospital quickly to begin treatment. Acute stroke therapies try to stop a stroke while it is happening by quickly dissolving the blood clot or by stopping the bleeding. Post-stroke rehabilitation helps individuals overcome disabilities that result from stroke damage. Drug therapy with blood thinners is the most common treatment for stroke.[3]

Prognosis

Although stroke is a disease of the brain, it can affect the entire body. A common disability that results from stroke is complete paralysis on one side of the body, called hemiplegia. A related disability that is not as debilitating as paralysis is one-sided weakness or hemiparesis. Stroke may cause problems with thinking, awareness, attention, learning, judgment, and memory. Stroke survivors often have problems understanding or forming speech. A stroke can lead to emotional problems. Stroke patients may have difficulty controlling their emotions or may express inappropriate emotions. Many stroke patients experience depression. Stroke survivors may also have numbness or strange sensations. The pain is often worse in the hands and feet and is made worse by movement and temperature changes, especially cold temperatures.[1]

Recurrent stroke is frequent; about 25 percent of people who recover from their first stroke will have another stroke within 5 years.[1]

Risks

A stroke involves loss of brain functions caused by a loss of blood circulation to areas of the brain. The blockage usually occurs when a clot or piece of atherosclerotic plaque breaks away from another area of the body and lodges within the vasculature of the brain.

Anyone can have a stroke, but certain behaviors and medical conditions can increase your chances. Fortunately, anyone can take steps to lower their risk.[5]

Medical conditions

High blood pressure. High blood pressure, also called hypertension, can greatly increase your risk for stroke. Smoking cigarettes, eating a diet high in salt, and drinking too much alcohol can all raise your blood pressure.

High blood cholesterol. High blood cholesterol can build up fatty deposits (plaque) on blood vessel walls. The deposits can block blood flow to the brain, causing a stroke. Diet, exercise, and family history affect blood cholesterol levels.

Heart disease. Common heart disorders can increase your risk for stroke. For example, coronary artery disease (CAD) increases your risk because a fatty substance called plaque blocks the arteries that bring blood to the heart. Other heart conditions, such as heart valve defects, irregular heartbeat (including atrial fibrillation), and enlarged heart chambers, can cause blood clots that may break loose and cause a stroke.

Diabetes. Having diabetes can increase your risk of stroke and can make the outcome of strokes worse. Diabetes is a condition that causes blood to build up too much sugar instead of delivering it to body tissues. High blood sugar tends to occur with high blood pressure and high cholesterol.

Overweight and obesity. Being overweight or obese can raise total cholesterol levels, increase blood pressure, and promote the development of diabetes.

Previous stroke or transient ischemic attack (TIA). If you have already had a stroke or a TIA, also known as a "mini-stroke," there is a greater chance that you could have a stroke in the future.

Sickle cell disease. This is a blood disorder that is associated with ischemic stroke, and mainly affects African-American and Hispanic children. A stroke can happen if sickle cells get stuck in a blood vessel and clog blood flow to the brain. About 10% of children with sickle cell disease will have a stroke.[5]

Behavior

The illustration shows how a stroke can occur during atrial fibrillation. If a clot (thrombus) forms in the left atrium of the heart, a piece of it can dislodge and travel to an artery in the brain, blocking blood flow through the artery. The lack of blood flow to the portion of the brain fed by the artery causes a stroke.

Tobacco Use: Smoking injures blood vessels and speeds up the hardening of the arteries. The carbon monoxide in cigarette smoke reduces the amount of oxygen that your blood can carry. Secondhand smoke can increase the risk of stroke for nonsmokers.

Alcohol Use: Drinking too much alcohol raises your blood pressure, which increases the risk for stroke. It also increases levels of triglycerides, a form of cholesterol, which can harden your arteries.

Physical Inactivity: Not getting enough exercise can make you gain weight, which can lead to increased blood pressure and cholesterol levels. Inactivity also is a risk factor for diabetes.[5]

Heredity

Family history. Having a family history of stroke increases the chance of stroke. Find out more about this type of risk at CDC's genomics and disease prevention Web site.

Age and gender. The older you are, the more likely you are to have a stroke. Men are at greater risk than women to have a stroke.1

Race and ethnicity. Blacks, Hispanics, and American Indian/Alaska Natives have a greater chance of having a stroke than do non-Hispanic whites or Asians. See CDC's interactive maps to learn more about race and the risk for stroke.[5]

Treatment

Generally there are three treatment stages for stroke: prevention, therapy immediately after the stroke, and post-stroke rehabilitation. Therapies to prevent a first or recurrent stroke are based on treating an individual's underlying risk factors for stroke, such as hypertension, atrial fibrillation, and diabetes. Acute stroke therapies try to stop a stroke while it is happening by quickly dissolving the blood clot causing an ischemic stroke or by stopping the bleeding of a hemorrhagic stroke. Post-stroke rehabilitation helps individuals overcome disabilities that result from stroke damage. Medication or drug therapy is the most common treatment for stroke. The most popular classes of drugs used to prevent or treat stroke are antithrombotics (antiplatelet agents and anticoagulants) and thrombolytics.[1]

Videos

[6] [7]

References

  1. 1.0 1.1 1.2 1.3 NINDS Stroke Information Page by the National Institute of Neurological Disorders and Stroke. Accessed January 2, 2011.
  2. Stroke by the Centers for Disease Control and Prevention. Accessed January 2, 2011.
  3. 3.0 3.1 Stroke Medline Plus, National Institute of Neurological Disorders and Stroke. Accessed January 2, 2011.
  4. 4.0 4.1 4.2 Types of Stroke by the Centers for Disease Control and Prevention. Accessed January 2, 2011.
  5. 5.0 5.1 5.2 5.3 Stroke: Risk Factors by the Centers for Disease Control and Prevention. Accessed January 2, 2011.
  6. YouTube
  7. YouTube

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