What happens when you have a stroke?

A stroke happens when a blood vessel in your brain: Gets blocked and stops the flow of blood to the brain. This is called an ischemic stroke.

What is a stroke?

A stroke happens when a blood vessel in your brain gets blocked and stops the flow of blood to the brainThis is called an ischemic stroke.

Picture of ischemic stroke. Source: National Heart, Lung and Blood Institute, National Institutes of Health

Bursts or bleeds in or around the brain. This is called a hemorrhagic stroke.

Picture of hemorrhagic stroke. Source: National Heart, Lung and Blood Institute, National Institutes of Health

What happens during a stroke?

Blood brings oxygen and nutrients to the body.  A burst or blocked blood vessel stops blood from reaching some parts of the brain. With no blood flow, parts of the brain will be damaged or die. The effects of a stroke will depend on where and how much of the brain was damaged and can affect how you think, see, move, feel and/or speak.  Learn about the functions of the brain.

What is a Transient Ischemic Attack (TIA)? 

Transient Ischemic Attack (TIA) happens when there is a temporary stoppage of blood flow and oxygen to the brain. The symptoms are like a stroke but only lasts less than 24 hours. This is often called a mini-stroke. It is a warning sign that you may have a stroke.

What causes a stroke?

A stroke often happens without warning signs. 

There are some things that make it more likely that someone will have a stroke:

Risk factors for stroke can be divided into two categories: risk factors you can’t change (non-modifiable risk factors) and risk factors you can change (modifiable risk factors).  Modifiable risk factors can be controlled by medications, medical treatment, or lifestyle changes. Non-modifiable risk factors cannot be changed.

Modifiable Risk Factors

  • Hypertension
  • Hypercholesterolemia
  • Diabetes
  • Atrial fibrillation
  • Sleep apnea
  • Being overweight or obese
  • Physical inactivity
  • Smoking
  • Excessive alcohol and drug abuseStress

Non-Modifiable Risk Factors

  • Advanced age
  • Gender
  • Family and medical history
  • Ethnicity
  • Prior stroke or TIA

Signs of a stroke

Are there warning signs before a stroke happens?

For most people a stroke happens suddenly.

What are the signs of a TIA or stroke?

The signs to look for are:

Signs of stroke

If you notice any of these warning signs, call 911 right away!

Credit: Northwestern Ontario Regional Stroke Network

Brain Hemispheres

Functions of the brain

The brain is divided into two large halves called hemispheres.



Do I know the types of tests that the doctor has ordered?



Commonly asked questions about stroke-related medications.

Stroke prevention clinics

Stroke Prevention Clinics

Stroke prevention clinics provide early assessment, treatment and education to people who have had a transient ischemic attack (TIA) or stroke, their families and caregivers.

Healthcare Team

Health Care Team

A list of health professionals that may care for you.

Having read the information in this section, consider the following:

  • Do I know what kind of stroke I had?
  • Do I know what caused my stroke?
  • Do I know what the symptoms of a stroke are?
  • Will I know what to do if I have symptoms of a stroke?
  • Do I have a plan in place if I have an emergency?

Where to get more information, help and support:

Heart and Stroke Foundation

Toronto Central Healthline

Aphasia Institute