Learn more about strokes, stroke causes, why people with high blood pressure are more at risk, and why it's so important to reduce your risk.

What is a stroke?

A stroke is a sudden interruption of blood flow to the brain. Without the oxygen and nutrients carried by the blood, brain cells begin to die. The longer blood flow is interrupted, the greater the risk of permanent brain damage and death.

There are two common types of stroke:

Type of stroke What happens
Ischemic stroke (80% of strokes)

A blood clot blocks blood flow to the brain. Ischemic strokes may be:

  • thrombotic: A blood clot forms in a blood vessel in the brain and blocks it.
  • embolic: A blood clot forms in another part of the body (such as the heart), moves into the brain, and blocks a blood vessel.
Hemorrhagic stroke (20% of strokes) Blood vessels rupture in the brain, causing blood to leak out. The leaking blood and the interruption of normal blood flow damage the brain.

Depending on the part of the brain affected, strokes can affect your vision, mobility, thoughts, memory, and speech. See "How could a stroke affect my health and lifestyle?" to learn more.

Some people may have a "mini-stroke," also called a TIA (transient ischemic attack). With a TIA, the blood flow to the brain is temporarily blocked. A TIA causes the same symptoms as a stroke, but the symptoms usually disappear within 24 hours. However, a TIA is still very serious because it could still cause brain damage, and because it is a warning that you are at risk of a stroke.

What is high blood pressure?

High blood pressure, also called hypertension, is a condition where the pressure inside the blood vessels is higher than normal.

It is very common - about one Canadian in 5 has high blood pressure.

Blood pressure is measured using a blood pressure cuff in the doctor's office. The measurement gives 2 numbers (e.g., 120/80):

  • The top number is your systolic blood pressure: the pressure in the blood vessels when the heart is contracting (squeezing blood out into the body).
  • The bottom number is your diastolic blood pressure: the pressure in the blood vessels when the heart is relaxing in between contractions.

When your blood pressure is higher than 140/90 (or higher than 130/80 for people with diabetes), your doctor will diagnose high blood pressure (usually after double-checking with a number of different readings).

You can't usually see or feel high blood pressure. But it can still take a toll on your health. People with high blood pressure have a higher risk of stroke, heart attacks, heart failure, kidney disease, or vision problems.

Find out how to manage your blood pressure to reduce your risk of stroke.

How does high blood pressure increase my stroke risk?

High pressure can damage the delicate walls of your blood vessels. If it affects the blood vessels of the brain, you could have a stroke. This could happen in one of two ways:

1. Blocking the blood supply to the brain:

  • Blood vessel walls become scarred, and fatty plaques build up in the walls. This narrows and blocks the blood vessels in the brain, causing a stroke.

2. Causing bleeding in the brain:

  • High blood pressure causes blood vessel walls to burst, causing bleeding in the brain.

High blood pressure is the biggest controllable risk factor for a stroke. But if you have high blood pressure, you can take action to try to change this! Get your blood pressure under control and you could reduce your stroke risk by up to 40%!

Learn more about other stroke risk factors, and find out what you can do to reduce your risk.

What are the symptoms of a stroke?

Stroke warning signs

Learn to recognize the warning signs of stroke. If you see them, respond immediately by calling 9-1-1 or your local emergency number. It can significantly improve survival and recovery.

Weakness - Sudden loss of strength or sudden numbness in the face, arm or leg, even if temporary.
Trouble speaking - Sudden difficulty speaking or understanding or sudden confusion, even if temporary.
Vision problems -Sudden trouble with vision, even if temporary.
Headache - Sudden severe and unusual headache.
Dizziness - Sudden loss of balance, especially with any of the above signs.

If you experience any of these symptoms, call 9-1-1 or your local emergency number immediately.

© Reproduced with the permission of the Heart and Stroke Foundation of Canada, 2011.

Print the stroke warning signs and put them on your fridge or in your wallet.

This list includes common stroke warning signs but is not a complete list of all possible warning signs. Some people may have additional warning signs not listed above.

How could a stroke affect my health and lifestyle?

The effects of a stroke vary from person to person: some people die, others recover completely, but many have effects that could last a lifetime.

Here's what could happen to you after a stroke:

Death 15%
Very severe disability (you will need long-term care) 10%
Moderate-to-severe disability (you can function on your own but with difficulty) 40%
Mild disability (your disability is inconvenient but does not have a major impact on your life) 25%
Complete recovery 10%

A stroke can affect many different parts of your life, depending on the areas of the brain that were damaged:

Type of problem What could happen? How could this affect my life?
Physical problems

You could have weakness or paralysis along one side of your body, painful muscle spasms, vision changes (double vision or "blind spots"), difficulty swallowing, constant pain, poor balance, or a loss of fine motor skills (the ability to make small, precise movements).

It might be harder for you to get around and do your usual activities.
Mental challenges

You could have trouble speaking, understanding speech, remembering recent events, or learning and remembering new information.

You could also have personality changes, poor judgment, and impulsive behaviour.
It could be harder for you to do your job and function day to day.
Emotional changes

You may also feel frustrated, angry, depressed, or emotionally out of control.

This could put a strain on your relationships.

Some of these problems may improve over time. Stroke rehabilitation can help people regain some of the function they have lost and live life to the fullest.