What Is a Stroke?

If you have a stroke, it means something has cut off your brain’s blood supply. It’s an emergency, because without oxygen and nutrients from the blood, the part of your brain that’s affected quickly starts to die. So you, or someone who’s with you, needs to call 911 right away. Symptoms include:

  • Sudden numbness or weakness on one side of the body
  • Not able to talk
  • Double or blurred vision in one eye
  • Sudden dizziness or falling

Sometimes called “brain attacks,” strokes happen in one of two main ways:

  1. A clot blocks the blood flow to your brain. These are “ischemic” strokes.
  2. A blood vessel bursts or leaks in your brain. Doctors call this a “hemorrhagic” stroke.

With either type of stroke, brain cells can’t live more than a few minutes without oxygen.




Strokes Caused by Blood Clots

These are when a clot stops the blood traveling through a vessel in the brain or neck. Most strokes -- 80%-90% -- are this type. Doctors call these "ischemic" strokes."

Some clots form inside a blood vessel and stay put, blocking blood flow in the brain. Doctors call this a “cerebral thrombosis.” The causes usually are high cholesterol and narrowed or hardened arteries that pump blood throughout the body.


A stroke can also happen if a clot forms in another part of your body -- usually in the heart or upper chest and neck -- and travels up through your bloodstream until it blocks the blood flow to your brain. This is a “cerebral embolism.”


Sometimes, a clot dissolves or dislodges on its own. This is a transient ischemic attack, or TIA. Although TIAs don’t injure the brain permanently, you can’t tell whether it’s a TIA while it’s happening, so you must call 911 at the first symptoms. Never wait to see if they pass, or it may be too late for treatments to help.

TIAs can also mean that you’re at risk for having a full-blown stroke later.


Strokes Caused by Bleeding

This happens because of bleeding in the brain. These "hemorrhagic" strokes are less common than the ischemic kind, but they can be more severe and deadlier.

Most often, it happens after an aneurysm -- a thinned or weakened spot on an artery that has ballooned from pressure -- bursts. Other times, the artery wall grows brittle over time from fatty plaque and then breaks open.

How to Lower Your Risk

Strokes can happen at any age, even to babies in the womb. Still, the odds of a stroke climb quickly after middle age.

To cut your odds of having a stroke:

Keep your blood pressure healthy. If you have high blood pressure (consistently over 130/80), this is the single biggest thing you can do to lower your odds of a stroke.

Avoid tobacco. Smoking cigarettes and chewing tobacco -- even secondhand smoke -- cause physical changes in your body. They can thicken your blood and make it more likely to clot and cause fatty buildup in your arteries.

Control your cholesterol levels. High levels of LDL, or "bad" cholesterol, make it more likely that plaque will build up in your arteries, putting you at greater risk of a clot that causes a heart attack or stroke.

Manage diabetes, if you have it. If it’s not under control, it can lead to a stroke by damaging your blood vessels.

Check your weight and waist. Your doctor can let you know if these numbers are in a healthy range. if you have a belly that’s bigger than 40 inches around for men or more than 35 inches for women, that may be especially risky.

WebMD Medical Reference Reviewed by James Beckerman, MD, FACC on July 12, 2017



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