When a stroke occurs, a blood vessel in the brain becomes blocked or bursts, sometimes causing permanent brain damage or even death. However, prompt treatment and follow-up care may protect brain cells and help patients lead healthy, productive lives.
Stroke is the third leading cause of death in North America, after cardiovascular disease and cancer, disabling more adults than any other condition.
There are two main types of strokes:
- Ischemic Stroke — This type of stroke accounts for approximately 80 to 85 percent of all strokes. With ischemic stroke, the blood supply to a part of the brain becomes blocked. This prevents oxygen and nutrients from reaching brain cells. Within a few minutes, these cells may begin to die.The underlying cause for this type of obstruction is usually atherosclerosis, a condition in which plaque or fatty deposits within the wall of the arteries in the brain and neck can lead to obstruction or narrowing. These fatty deposits can cause cerebral thrombosis or cerebral embolism. With a cerebral thrombosis, a blood clot forms within the blood vessel. Cerebral embolisms are clots that can form at another location in the circulatory system, break loose from an artery wall or from the inside lining of the heart, travel through the brain’s blood vessels and can lodge in an artery in the brain.
- Hermorrhagic Stroke — With hemorrhagic stroke a blood vessel within the brain leaks or ruptures and bleeds into the surrounding brain tissue. This is called an intracerebral hemorrhage. The blood can accumulate and exert pressure on the surrounding tissue.High blood pressure is a common cause of intracerebral hemorrhage. In a subarachnoid hemorrhage, blood leaks under the lining of the brain. This is often caused by a small bubble on an artery known as an aneurysm.
Common symptoms of stroke include:
- Sudden paralysis of a leg, arm or one side of the face
- Sudden trouble speaking or understanding speech
- Sudden vision problems, such as blurred or double vision
- Sudden loss of coordination or problems with balance
- A severe, sudden headache without apparent cause
- Sudden numbness, weakness or dizziness
If you are experiencing any symptoms of stroke, you should go to a doctor or hospital right away, preferably by dialing 911.
Transient Ischemic Attack (TIA) — Although strokes typically occur without warning, some people may feel a temporary numbness, weakness or tingling in one arm or leg, or problems with speech, vision or balance before the actual onset of the stroke. This occurs because the blood supply to the brain is temporarily reduced, called a transient ischemic attack (TIA). These episodes usually last a few minutes to hours and may not cause immediate permanent injury to the brain. However, a TIA is a sign that the risk of a permanent stroke is great. TIA is an emergency. Patients with TIAs should be seen right away, just like those with stroke symptoms that don’t go away.
Risk factors for stroke that cannot be changed:
- Family History — The risk of having a stroke is higher for people whose parents or siblings have had a stroke.
- Age — Stroke risk increases with age — doubling every 10 years after age 55.
- Gender — Before age 55, men are more likely than women to have strokes. After 55, the risk is the same for men and women. However, women are more likely than men to die of stroke.
- History of Prior Stroke, TIA or Heart Attack — A person who has had a stroke in the past is at much greater risk for having another one. Risk of stroke after a TIA is greatest within the first 48 to 72 hours. Therefore, you should seek immediate medical attention for all acute neurologic changes, even if they have resolved.
- Race — African Americans have higher incidence of stroke and a higher risk of death from a stroke than Caucasians do. Asian Americans have higher incidence of hemorrhagic stroke than other ethnic groups.
Risk factors for stroke that are modifiable:
- High Blood Pressure — This is probably the most important modifiable risk factor for stroke. Controlling high blood pressure will greatly reduce your risk of stroke and heart attack.
- Cardiovascular Disease — Congestive heart failure, a previous heart attack, a diseased aortic valve and atrial fibrillation can all raise the risk of stroke.
- Cigarette Smoking — The risk of stroke is two to three times greater for smokers versus nonsmokers. The use of oral contraceptives with cigarette smoking greatly increases the risk of stroke.
- Carotid Artery Disease — Fatty deposits from atherosclerosis may cause significant narrowing in the carotid arteries. This can limit blood flow to the brain as well as acts as a potential source for cerebral emboli.
- Diabetes — Diabetes doubles stroke risk. Many people with diabetes also have high blood pressure, obesity and high cholesterol, which increase their stroke risk even further.
- Undesirable Blood Cholesterol Levels — High blood levels of low-density lipoprotein (LDL) cholesterol and low levels of high-density lipoprotein (HDL) cholesterol increase stroke risk.
- Obesity — Excess weight can double the risk of an ischemic stroke.
- Lack of Exercise and Physical Activity — Both increase the risk of high blood pressure and therefore the risk for stroke. Taking the stairs, going on a brisk walk, doing some kind of activity for at least 30 minutes everyday will help decrease your stroke risk.
- Use of Birth Control and Hormone Therapy — Women who use birth control pills, especially if they smoke and are over the age of 35, have a higher risk of stroke. There is also a higher risk of stroke among women using hormone therapy for menopause.
It is critical to come to the hospital immediately if you experience a stroke because treatments might reduce or completely reverse the brain injury from stroke. These treatments must be given within the first few hours of stroke symptoms. These treatments include administration of a t-PA — a drug that opens blocked blood vessels — or devices to remove the clot from the brain using a catheter (thrombolysis).
Post-stroke prevention may involve the administration of antiplatelet drugs such as aspirin, control and reduction of hypertension, the use of statins, and in selected patients with carotid endarterectomy, the use of anticoagulants.
Treatment to recover any lost function is stroke rehabilitation, involving health professions such as speech and language therapy, physical therapy and occupational therapy.