Merck Manual

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The Manual's Editorial Staff

Last full review/revision Sep 2021| Content last modified Sep 2021
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What is a stroke?

A stroke is a sudden brain problem that happens when a blood vessel in your brain either gets blocked or breaks open and bleeds.

Part of your brain stops getting blood. Brain tissue that doesn't get blood stops working and dies. If a lot of brain tissue is affected, your symptoms will be more severe.

If a blocked blood vessel opens up quickly on its own, your symptoms may go away completely. This is called a transient ischemic attack Transient Ischemic Attacks (TIA) Transient is something that goes away quickly. Ischemic means no blood flow is getting to an organ. So a TIA is a temporary brain problem caused by a lack of blood flow to part of your brain... read more (TIA), which is a warning sign that you could soon have a stroke.

  • Stroke symptoms come on suddenly

  • You get different symptoms depending on what part and how much of your brain was affected

  • You may have face numbness or drooping, a weak arm or leg, difficulty seeing, trouble speaking, or a very bad headache

  • Symptoms often involve only one side of your body

  • Even though brain tissue that dies never comes back, sometimes other parts of your brain learn to take over the job of the damaged part

  • If you have any symptom that makes you think you're having a stroke, you should go to an emergency department

  • Treatment with medicines may help limit brain damage and prevent a future stroke

What causes a stroke?

Strokes are caused by a lack of blood flow to part of your brain from:

  • A blocked blood vessel in your brain

  • A bleeding blood vessel in your brain

A blocked blood vessel can be caused by:

  • A blood clot that forms in a blood vessel in your brain

  • A blood clot that forms in your heart or a blood vessel near your heart that breaks loose, moves through your bloodstream, and gets stuck in a blood vessel in your brain

  • A fat deposit (plaque) that breaks off the lining of a blood vessel, travels to your brain, and gets stuck in a blood vessel there

A bleeding blood vessel in your brain can be caused by:

  • An aneurysm that bursts open

An aneurysm is a bulge in the wall of a blood vessel. If you have a stroke from an aneurysm, it's likely you were born with that aneurysm. Other aneurysms develop later from having high blood pressure High Blood Pressure Each heart beat pushes blood through your arteries. Arteries are the blood vessels that carry blood from your heart to your body. Blood pressure is the pressure of blood in your arteries. Without... read more for many years.

Clogs and Clots: Causes of Ischemic Stroke

When an artery that carries blood to the brain becomes clogged or blocked, an ischemic stroke can occur. Arteries may be blocked by fatty deposits (atheromas, or plaques) due to atherosclerosis. Arteries in the neck, particularly the internal carotid arteries, are a common site for atheromas.

Arteries may also be blocked by a blood clot (thrombus). Blood clots may form on an atheroma in an artery. Clots may also form in the heart of people with a heart disorder. Part of a clot may break off and travel through the bloodstream (becoming an embolus). It may then block an artery that supplies blood to the brain, such as one of the cerebral arteries.

Clogs and Clots: Causes of Ischemic Stroke

What are the risk factors for having a stroke?

The major risk factors for stroke are:

Other risk factors include:

What are the symptoms of a stroke?

Symptoms start quickly, usually within a few minutes. A severe stroke may kill you right away.

Many different symptoms can occur, depending on which part of your brain isn't getting enough blood:

  • Feeling weak or numb on one side of your face or body

  • Difficulty talking

  • Difficulty swallowing

  • Trouble understanding what people say

  • Confusion

  • Loss of coordination

  • Blind spots in your vision

Brain swelling (edema) can result from a severe stroke. It causes symptoms several hours to a day or two later. You may become confused or go into a coma. Brain swelling is one of the main reasons people die from a stroke.

What are the long-term problems after a stroke?

After a stroke, you may:

How will my doctor know if I had a stroke?

Doctors will also do tests to find out what caused your stroke:

How do doctors treat a stroke?

First, you'll be admitted to the hospital.

In the hospital

Doctors can't repair brain tissue damaged by a stroke. However, your doctor may give treatments to:

  • Remove a blood clot or close a bleeding vessel

  • Keep brain damage from getting worse by getting your heart rate, blood pressure, and body temperature back to normal

  • If you had a blood clot, prevent another one by giving you blood thinners

  • Help you function as best you can (with rehabilitation)

If your stroke was caused by a blood clot, doctors can sometimes break up the clot with medicine (clot-busting drugs). If the clot is broken up quickly enough, your symptoms may go away completely. However, the drugs must be given within the first few hours. Also, some people have a high risk of complications from these drugs and can't use them safely.

If your stroke was caused by narrowing of the blood vessels in your neck, doctors may do surgery to open them. Or they might put a small tube (stent) in the blood vessel to keep it open.

If your stroke was caused by a bleeding blood vessel, doctors can sometimes close the leak. Doctors put a small metal coil in the leaking vessel or do surgery to close it.

Rehabilitation (rehab) helps you function better after a stroke. Rehab:

  • Starts in the hospital, usually within 1 or 2 days after your stroke

  • Includes exercises to teach healthy areas of your brain to do the jobs injured areas used to do

  • Continues after you leave the hospital

After you leave the hospital

Where you go depends on how severe your symptoms are and how much help you need. You may go:

  • Home

  • To a rehabilitation facility

  • To a nursing home

Wherever you go, you may need treatment for months or years. Doctors will also try to prevent another stroke and help you adjust to challenges in your daily life. Usually they'll have you:

What are your chances of recovering after a stroke?

Usually, the more you improve during the first few days, the more you'll continue to improve. You generally can expect to continue to improve for 6 months after the stroke.

Out of 10 people who have a stroke, one usually recovers almost completely, 3 recover most function, 4 have disabilities needing special care, and 2 die in the hospital.

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