(Cerebrovascular Accident · Ischemic Stroke · Hemorrhagic Stroke)
In this condition factsheet:
The Facts on Stroke
Stroke is a sudden loss of brain function caused by the interruption of blood flow to the brain, as a result of either an ischemic stroke (a blood clot) or a hemorrhagic stroke (the rupture of a blood vessel and bleeding into or around the brain).
The interruption of blood flow to the brain causes brain cells (neurons) in the affected area to die. The effects of a stroke depend upon which part of the brain was injured and how much damage has occurred. About 80% of strokes are ischemic and 20% are hemorrhagic.
Stroke is a leading cause of disability worldwide, and approximately 300,000 Canadians are living with the effects of a stroke. It is also the third leading cause of death in Canada. About 60% of people who have had a stroke are left with some form of disability such as paralysis, sensory loss, memory loss, language problems, and vision problems. Some people may also suffer from depression or other emotional conditions after a stroke.
Risk factor modification, medications and, in some cases, surgery can help to minimize the risk of having a stroke.
Causes of Stroke
An ischemic stroke is the result of blockage in blood flow to the brain caused by a blood clot. The buildup of plaque in the artery wall (atherosclerosis, or "hardening of the arteries") is an underlying cause for many ischemic strokes.
Atherosclerosis is a process in which fatty deposits (plaques) build up inside the blood vessels of the body, particularly in the carotid arteries of the neck, the coronary arteries of the heart, and the arteries of the legs. Atherosclerotic plaques can lead to a stroke by causing blockage of blood flow, or by dislodged plaque material (emboli) that can travel to the brain.
A hemorrhagic stroke is caused by bleeding into the brain (intracerebral hemorrhage) or bleeding around the brain (subarachnoid hemorrhage), which results from the breakage of a blood vessel. Brain hemorrhages may result from uncontrolled high blood pressure, and, in some cases, can be caused by structural problems within the blood vessels (e.g., aneurysms or vascular malformations).
There are numerous risk factors that can cause a stroke.
Factors you can't control are:
- age: The risk of stroke increases with advancing age.
- ethnicity: People of First Nations, African, Hispanic, and South Asian descent have greater rates of high blood pressure and diabetes. These conditions increase the risk of stroke.
- family history: The risk of stroke may be higher if a parent or sibling has had a stroke before the age of 65.
- gender: Men have a higher risk of stroke than women who have not reached menopause.
- prior stroke or transient ischemic attack (TIA): Up to one-third of people who survive a first stroke or TIA will have another stroke within 5 years.
Factors you can control are:
- high blood pressure
- heart disease or atrial fibrillation (irregular heartbeat)
- cigarette smoking
- high cholesterol
- physical inactivity
- high alcohol intake (more than 10 drinks per week for women or more than 15 drinks per week for men)
Other factors that can lead to a stroke are:
- other medical conditions such as amyloid angiopathy and antiphospholipid antibody syndrome
- use of illicit drugs such as cocaine or LSD
- some medications, such as tamoxifen*, phenylpropanolamine, and thrombolytics
Other factors such as oral contraceptive use, hormone replacement therapy, or pregnancy and childbirth in women with pre-existing medical conditions may increase the risk of stroke in specific cases. Talk to your doctor about risk factors that may be relevant to you and your risk of stroke.
Symptoms and Complications of Stroke
The symptoms of stroke appear suddenly, over a few minutes or hours or at most a couple of days. Individuals should be able to recognize the 5 main symptoms of stroke and seek immediate medical attention if any of these symptoms occur:
- sudden paralysis or numbness of the face, arm, or leg (usually on only one side of the body)
- sudden loss of speech or trouble understanding speech
- sudden loss of vision (often in one eye only) or double vision
- sudden dizziness or loss of balance or coordination
- sudden severe and unusual headache (often described as "the worst headache of my life") with no known cause
A transient ischemic attack (TIA) is a "mini-stroke" caused by a temporary interruption of blood flow to the brain. TIA symptoms are the same as those of a stroke except that the symptoms disappear within a few minutes to hours, usually lasting no longer than 24 hours. However, TIAs require immediate medical attention just like strokes. TIAs are important warning signs indicating you may be at risk of having a stroke in the future. Medical treatment is required.