Step inside the human body to see how your brain and vascular system are vitally linked to keep you alive and well. Though your brain occupies only 5% of your body, it needs 20% of the blood supply to function properly. When that blood supply is restricted or blocked, the life-giving oxygen in the blood can't get to the delicate brain tissues that need it. The tissues start to die, and parts of the brain stop working. You can think of a stroke as the same as a heart attack, except it happens in your brain. In this video, you can see a stroke "in action," understand the different types of strokes, the causes, the symptoms to look for, what to do in an emergency and what you can do to avoid one.

Your Brain Needs Oxygen

Your brain is hungry. It's your body's single largest consumer of oxygen. Although your brain represents only about 2% of your body's weight, it utilizes about 20% of your body's blood. Brain cells are particularly vulnerable to a decrease of oxygen supply to the brain (termed hypoxia). Normally, brain cells don't come into contact with the blood. Read more

Clogged Carotids

Because your brain needs so much blood, it's well supplied with an abundance of arteries, the blood vessels that carry oxygenated blood from your heart to your body's tissues. There are two pairs of big arteries that carry blood from your heart up to your brain:

• The internal carotid arteries, which run along the front of your neck
• The vertebral arteries, which run along the back of your neck

In the skull, the internal carotid arteries divide into several branches. The vertebral arteries unite to form the basilar artery, which then also divides into several branches. Read more

Degree of Blockage

Healthy arteries are flexible and have little or no plaque buildup. They allow blood to flow freely and can constrict or dilate in response to changes in blood pressure and your body's varying needs for blood supply. But in atherosclerosis, plaques accumulate and arterial walls swell and become thick and stiff. Arteries clogged by atherosclerosis are susceptible to partial or complete blockage by debris or blood clots. The result may be a transient ischemic attack (TIA) or an ischemic stroke. Read more

Types of Stroke

Strokes can be divided into two types: ischemic and hemorrhagic. In ischemic strokes, damage is caused by too little blood in the brain; in hemorrhagic strokes, by too much blood in the skull.

Ischemic stroke
About 83% of all strokes are ischemic. Ischemic strokes are usually caused by atherosclerosis, when fatty deposits, made up mostly of cholesterol, form on the walls of the arteries. The arteries stiffen and become narrower. The resulting, severely reduced blood flow is called ischemia. Read more

Risk Factors

Some of the risk factors for stroke are beyond your control and can't be changed. These include:

• Genetics. Having a family history of stroke
• Age. Being 55 or over
• 
  Gender. Slightly more than half of all strokes occur in men, but more than 60% of stroke deaths occur in women, possibly because women tend to be older when they have strokes
• Medical history. Having had a prior stroke, TIA, or heart attack

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Symptoms, Test & Diagnosis

Screening and Diagnosis
A number of different tests may be used to examine you if you have risk factors for stroke, like high blood pressure and high cholesterol levels. They may also be used for diagnosis if you're having (or have had) a stroke.

• Computerized tomography (CT). CT scanning provides images of your brain and shows hemorrhages. More information is provided by computerized tomography angiography (CTA). In CTA, a dye is injected into your vein, and X-rays are used to create a three-dimensional image of blood vessels in your brain and neck that your doctor can examine for aneurysms, narrowing of the arteries, or blood vessel malformations.

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Treating Stroke

Treatment: Ischemic Stroke
The main goal in treating ischemic stroke is to restore blood flow to the brain.

Treatment with medications

• Aspirin. An antiplatelet medication that decreases blood clot formation by preventing the smallest blood cells (platelets) from sticking together. Aspirin is the best treatment immediately after a stroke to prevent further stroke. Ischemic stroke patients are typically given aspirin in the emergency room.
• Heparin and warfarin (Coumadin). Anticoagulants that help prevent clots from forming
• Tissue plasminogen activator (TPA). A potent clot-busting drug that may improve chances of recovery for some patients

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Life After Stroke

Complications of Stroke
The complications of stroke can be severe and include:

• Paralysis or loss of muscle movement
• Difficulty speaking
• Difficulty swallowing
• Loss of bowel or bladder control
• Memory loss or troubles with understanding
• Pain or numbness
• Herniation. The brain may swell, forcing it down in the skull and through the rigid structures that separate the brain into compartments. This affects the respiratory center in the lower part of the brain stem, and can cause irregular breathing, coma, and even death.

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