A stroke occurs when there is a sudden disruption in blood flow to the brain, usually because a blood vessel bursts or is blocked by a clot. This deprives the brain tissue of oxygen and food, and can cause permanent damage to brain cells in a matter of minutes.
According to the World Health Organization , 15 million people worldwide suffer a stroke each year. Of these, 5 million die and another 5 million are left permanently disabled. This makes strokes the second leading cause of death in the world.
Although stroke carries a high risk of death, the effects of a stroke may be mild or severe, temporary or permanent. This depends on a number of factors including which brain cells are damaged, how much of the brain is affected and how quickly the blood supply is restored to the area.
A person with stroke symptoms needs immediate medical attention. These symptoms come on very quickly, and commonly consist of sudden numbness in one side of the body, and problems with walking, balance, speaking and vision. With prompt treatment, brain damage and further complications can be minimised.
The good news is that strokes can be treated and prevented with better control of major risk factors such as smoking, high blood pressure and high cholesterol. Learn more about how you can minimise your risk and recognise the warning signs of stroke in this section.
As different areas of the brain are responsible for different functions, the symptoms of stroke vary depending on which area of the brain is damaged. If you think that you or someone else may be having a stroke, some warning signs to look for are:
The sudden appearance of one or more of these symptoms is a warning sign that a stroke may be in progress. Seek immediate medical attention if you notice these symptoms. The longer a stroke goes untreated, the greater the potential for brain damage or disability.
A stroke is caused by the sudden interruption of the blood supply to the brain. There are two types of stroke: ischemic and hemorrhagic.
Ischemic stroke is by far the most common type of stroke, accounting for a large majority of strokes. It occurs as a result of an obstruction within a blood vessel supplying blood to the brain. The American Association of Neurological Surgeons divide ischemic stroke into 2 types: thrombotic and embolic. A thrombotic stroke occurs when a blood clot, called a thrombus, blocks an artery to the brain and stops blood flow. An embolic stroke is when a piece of plaque or thrombus travels from its original site and blocks an artery downstream.
Hemorrhagic stroke occurs when a weakened blood vessel ruptures. It can be caused by hypertension, or rupture of an aneurysm or vascular malformation. An intracerebral hemorrhage occurs when there is bleeding directly into the brain tissue, which often forms a clot within the brain. A subarachnoid hemorrhage occurs when the bleeding fills the cerebrospinal fluid spaces around the brain. Both conditions are very serious.
There are many risk factors that can increase your chance of a stroke. The risk factors that can be changed or treated include:
The following risk factors cannot be changed:
To diagnose a stroke, your doctor will first ask you questions about your symptoms and review your medical history for stroke risk factors. He or she will also conduct a physical exam to check your mental alertness and your coordination and balance. During the physical exam, your doctor may look for signs of numbness or weakness in your face, arms, and legs and assess whether you have trouble speaking and seeing clearly.
To diagnose a stroke, imaging tests will need to be conducted. Your doctor may recommend any of the following:
If it is clear that you are having a stroke, your evaluation will include tests to check for a cause. You may have a chest x-ray and an electrocardiogram (ECG) to check for heart problems. Blood tests will evaluate your blood cell counts, liver and kidney function, and the ability of your blood to clot. These tests are done to help your doctor make choices about your treatment.
Generally there are three treatment stages for stroke: prevention, therapy immediately after the stroke (acute stroke therapy), and post-stroke rehabilitation.
Therapies for stroke prevention treat your underlying risk factors for stroke such as high blood pressure, atrial fibrillation and diabetes. Preventative treatment is often focused on healthy lifestyle changes and taking regular medications for any conditions that can lead to a stroke. In rare cases, preventative surgery may be required. See Stroke Prevention for more details.
Acute stroke therapies try to stop a stroke while it is happening by quickly dissolving the blood clot causing an ischemic stroke or by stopping the bleeding of a hemorrhagic stroke.
The most effective treatment for strokes caused by a clot is a powerful clot-dissolving medication called tissue plasminogen activator (T-PA). T-PA can restore blood flow and oxygen to brain tissue affected by a stroke, but it must be given within three hours of when stroke symptoms begin. Other clot-prevention medications, such as heparin, are used in later hours after a stroke. These medicines prevent existing blood clots from getting bigger and new clots from forming. Hemorrhagic stroke on the other hand, may require surgery to remove the hemorrhaged blood and relieve pressure on the brain.
Post-stroke rehabilitation helps individuals overcome disabilities that result from stroke damage. A person who has experienced a significant stroke of any type usually is hospitalized for observation in case the symptoms worsen. Hospitalization is often followed by a period of residence at a rehabilitation center. There, additional therapy may be provided intensively. The goal of rehabilitation is to maximize recovery.
People who have had a stroke may need help with self-care or feeding. Early intervention by an occupational therapist and physical therapist is helpful. These therapists can help a person work around a new disability and regain strength after brain injury.
Knowing your stroke risk factors and adopting a healthy lifestyle are the best steps you can take to prevent a stroke. Some tips are: