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You are here : 3-RX.com > Medical Encyclopedia > Diseases and Conditions > Stroke from Carotid Stenosis
      Category : Health Centers > Stroke

Stroke from Carotid Stenosis

Alternate Names : Brain Attack

Overview, Causes, & Risk Factors | Symptoms & Signs | Diagnosis & Tests | Prevention & Expectations | Treatment & Monitoring

A stroke is the death of brain tissue that occurs when the brain does not get enough blood and oxygen. A stroke from carotid stenosis occurs when the arteries supplying the brain are narrowed and blood flow to the brain is impaired.

What is going on in the body?

A stroke from carotid stenosis is classified as an ischemic stroke, which means it happens when the blood supply to the brain is interrupted. Plaque, or firm layers of cholesterol, builds up on the internal surface of the carotid arteries which bring blood and oxygen to the brain. The plaque buildup causes a narrowing of the blood vessels.

The narrowing of these blood vessels, known as carotid stenosis, causes a decreased blood flow to the brain. The brain cells then die from lack of oxygen. The blood then damages the brain cells. The products released when cells die cause swelling in the brain. Since the skull doesn't allow much room for expansion, this swelling can damage the brain tissue even further.

Stenosis of the carotid arteries may occur over many years. When the surface of the plaque in an artery cracks or ruptures, clot-forming substances in the blood rapidly gather at the site. A clot, called a thrombus, then forms in the artery.

The clot reduces blood flow and deprives the brain of blood, oxygen, and nutrients. This can lead to a stroke, or brain attack. If part of the clot breaks off, it can be carried by the bloodstream to block smaller arteries in the brain. The portion of the clot that breaks off is called an embolus.

What are the causes and risks of the condition?

A stroke from carotid stenosis is caused by narrowing of one or more of the arteries supplying the brain with oxygen-rich blood. The narrowing is caused by the buildup of plaque on the inner walls of arteries supplying the brain. As plaque builds up in a person's arteries, the blood flow is interrupted and the person's risk of stroke increases. The person's risk of stroke from carotid stenosis is increased if other risk factors for stroke are also present.

The American Heart Association has recently issued guidelines for stroke prevention. The guidelines discuss risk factors for stroke in 3 categories: nonmodifiable, well-documented modifiable, and less well-documented or potentially modifiable.

The nonmodifiable factors are ones that cannot be changed by the individual and include:

  • increasing age. A person's risk of stroke doubles each year after age 55.
  • race. Strokes occur approximately twice as often in blacks and Hispanics as they do in whites.
  • gender. Men have a 50% higher chance of stroke than women do.
  • family history of stroke or transient ischemic attack (TIA). A TIA is a short, reversible form of stroke that may serve as an early warning sign of stroke.
  • Well-documented modifiable risk factors are those that can be changed by the individual in conjunction with his or her healthcare provider. These factors are linked to stroke by strong research findings, and there is documented proof that changing the risk factor lowers a person's risk of stroke. These factors include:

  • high blood pressure
  • smoking
  • diabetes
  • asymptomatic carotid stenosis, or narrowing of one of the arteries in the neck
  • sickle cell anemia, a blood disorder that forms abnormal red blood cells
  • high cholesterol levels in the blood, including total cholesterol and LDL or "bad cholesterol." Low levels of HDL or "good cholesterol" are also cause for concern.
  • atrial fibrillation, an abnormal heart rhythm
  • Less well-documented or potentially modifiable risk factors for stroke are those that have less proof of either a link to stroke or the impact of modifying the risk factor. These factors include:

  • obesity
  • sedentary lifestyle
  • alcohol abuse
  • high blood levels of homocysteine, a blood component sometimes associated with a higher risk of stroke
  • drug abuse
  • blood disorders, such as blood that clots easily or deficiencies of various blood components
  • hormone replacement therapy (HRT). The AHA currently states that the risk of stroke associated with HRT appears low but needs further study.
  • use of birth control pills, or oral contraceptives
  • inflammatory processes, such as a chronic infection with chlamydia
  • Several recent studies have identified factors that seem to increase or decrease the risk of stroke in particular groups of people. These studies, which warrant further investigation, include these findings:

  • People who were treated for high blood pressure with thiazide diuretics, such as hydrochlorothiazide, had a significantly lower stroke risk than people on ACE inhibitors or calcium channel blockers.
  • Women ages 39 to 50 who ate more fish and omega-3 polyunsaturated fatty acids had a reduced risk of stroke. This was particularly true in women who did not take aspirin regularly.
  • Women ages 15 to 44 who had 2 drinks of wine a day had a 40% to 60% lower risk of stroke than women who did not drink alcohol.
  • Phenylpropanolamine, a compound contained in appetite suppressants and cold remedies, significantly increased the risk of hemorrhagic stroke in women 18 to 49 years of age. The Food and Drug Administration (FDA) has since asked manufacturers to remove phenylpropanolamine from their products.
  • In one study, people who were treated in emergency departments for transient ischemic attacks (TIA) had a 25% chance of having a stroke or other serious health event within the next 90 days.

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    Next section

       

    Stroke from Carotid Stenosis: Symptoms & Signs

    Author: Tamara Miller, MD
    Reviewer: Eileen McLaughlin, RN, BSN
    Date Reviewed: 07/13/01



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