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Every two seconds, someone somewhere in the world experiences a stroke.
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And one out of every six people will have one at some point in their lives.
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Strokes deprive brain cells of oxygen and are one of the most common causes of death and a leading cause of preventable disability.
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When someone experiences a stroke, quick medical care is critical , and can often help avoid permanent brain damage.
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But what causes strokes in the first place?
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And what can doctors do to treat them?
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The brain makes up just 2% of your body's mass but consumes more than 20% of the oxygen in your blood.
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That oxygen is carried to the brain through a system of arteries.
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Carotid arteries supply the front of the brain, and vertebral arteries supply the back.
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These are connected to each other, and divide into smaller and smaller vessels that get billions of neurons the oxygen they need.
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If the blood flow is interrupted, oxygen delivery stops and brain cells die.
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There are two ways this can happen.
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Hemorrhagic strokes are when a perforated vessel allows blood to leak out.
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But the more common type is the ischemic stroke, when a clot blocks a vessel and brings blood flow to a halt.
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Where do these clots come from?
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On rare occasions, a sudden change in heart rhythm prevents the upper chambers of the heart from contracting normally.
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This slows down blood flow, allowing platelets, clotting factors, and fibrin to stick together.
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The clot can be carried up towards the arteries and blood vessels supplying the brain until it gets to one it can't squeeze through.
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This is called an embolism and it cuts off the oxygen supply to all the cells downstream.
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The brain doesn't have pain receptors, so you can't feel the blockage itself.
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But oxygen deprivation slows brain function and can have sudden, noticeable effects.
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For example, if the affected area is responsible for speech, an individual's words may be slurred.
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If the stroke affects a part of the brain that controls muscle movement, it can cause weakness, often just on one side of the body.
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When this happens, the body will immediately try to compensate by diverting blood flow to the affected area, but this isn't a perfect solution.
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Eventually, the oxygen-deprived cells will start to die, leading to brain damage that may be severe or permanent.
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That's why it's important to get medical care as fast as possible.
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The first line of treatment is an intravenous medication called Tissue Plasminogen Activator, which can break up the blood clot and allow blood to flow again in the compromised artery.
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If it's delivered within a few hours, this medication greatly increases the chance of surviving the stroke and avoiding permanent consequences.
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If Tissue Plasminogen Activator cannot be given because the patient is on certain medications, has history of major bleeding, or the clot is particularly large, doctors can perform a procedure called an endovascular thrombectomy.
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Using a fluorescent dye that illuminates the blood vessels under a strong x-ray, the physician inserts a long, thin, flexible tube called a catheter into an artery in the leg and maneuvers it all the way to the blockage.
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A retriever is passed through this catheter.
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It expands and anchors into the clot when it's just past it.
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The catheter then pulls the clot out when it's removed.
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These treatments need to be delivered as soon as possible
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to preserve brain function,
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which means figuring out fast if someone is having a stroke.
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So how can you tell?
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Here are three quick things to try:
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1. Ask the person to smile.
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A crooked mouth or facial drooping can indicate muscle weakness.
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2. Ask them to raise their arms.
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If one drifts downward, that arm weakness is also a sign of a stroke.
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3. Ask them to repeat a simple word or phrase.
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If their speech sounds slurred or strange,
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it could mean that the language area of their brain is oxygen-deprived.
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This is sometimes called the FAST test, and the T stands for time.
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If you see any of those signs, call emergency services right away.
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Lives may depend on it.
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