What is a stroke?
A stroke, or brain attack, happens when blood flow to your brain is stopped. It is an emergency situation.
The brain needs a constant supply of oxygen and nutrients in order to work well. If blood supply is stopped even for a short time, this can cause problems. Brain cells begin to die after just a few minutes without blood or oxygen.
When brain cells die, brain function is lost. You may not be able to do things that are controlled by that part of the brain. For example, a stroke may affect your ability to:
- Think and remember
- Control your bowel and bladder
- Control your emotions
- Control other vital body functions
A stroke can happen to anyone at any time.
What causes a stroke?
A stroke is caused when blood flow to your brain is stopped or disrupted.
There are 2 kinds of stroke: ischemic and hemorrhagic.
- Ischemic stroke. This is the most common type of stroke. It happens when a major blood vessel in the brain is blocked. It may be blocked by a blood clot. Or it may be blocked by a buildup of fatty deposit and cholesterol. This buildup is called plaque.
- Hemorrhagic stroke. This occurs when a blood vessel in your brain bursts, spilling blood into nearby tissues. With a hemorrhagic stroke, pressure builds up in the nearby brain tissue. This causes even more damage and irritation.
Who is at risk for a stroke?
Anyone can have a stroke at any age. But your chance of having a stroke increases if you have certain risk factors. Some risk factors for stroke can be changed or managed, while others can’t.
Risk factors for stroke that can be changed, treated, or medically managed:
- High blood pressure. Blood pressure of 140/90 or higher can damage blood vessels (arteries) that supply blood to the brain.
- Heart disease. Heart disease is the second most important risk factor for stroke, and the major cause of death among survivors of stroke. Heart disease and stroke have many of the same risk factors.
- Diabetes. People with diabetes are at greater risk for a stroke than someone without diabetes.
- Smoking. Smoking almost doubles your risk for an ischemic stroke.
- Birth control pills (oral contraceptives)
- History of TIAs (transient ischemic attacks). TIAs are often called mini-strokes. They have the same symptoms as stroke, but the symptoms don’t last. If you have had one or more TIAs, you are almost 10 times more likely to have a stroke than someone of the same age and sex who has not had a TIA.
- High red blood cell count. A significant increase in the number of red blood cells thickens the blood and makes clots more likely. This raises the risk for stroke.
- High blood cholesterol and lipids. High cholesterol levels can contribute to thickening or hardening of the arteries (atherosclerosis) caused by a buildup of plaque. Plaque is deposits of fatty substances, cholesterol, and calcium. Plaque buildup on the inside of the artery walls can decrease the amount of blood flow to the brain. A stroke occurs if the blood supply is cut off to the brain.
- Lack of exercise
- Excessive alcohol use. More than 2 drinks per day raises your blood pressure. Binge drinking can lead to stroke.
- Illegal drugs. IV (intravenous) drug abuse carries a high risk of stroke from blood clots (cerebral embolisms). Cocaine and other drugs have been closely linked to strokes, heart attacks, and many other cardiovascular problems.
- Abnormal heart rhythm. Some types of heart disease can raise your risk for stroke. Having an irregular heartbeat (atrial fibrillation) is the most powerful and treatable heart risk factor of stroke.
- Cardiac structural abnormalities. Damaged heart valves (valvular heart disease) can cause long-term (chronic) heart damage. Over time, this can raise your risk for stroke.
Risk factors for stroke that can’t be changed:
- Older age. For each decade of life after age 55, your chance of having a stroke more than doubles.
- Race. African Americans have a much higher risk for death and disability from a stroke than whites. This is partly because the African-American population has a greater incidence of high blood pressure.
- Gender. Stroke occurs more often in men, but more women than men die from stroke.
- History of prior stroke. You are at higher risk for having a second stroke after you have already had a stroke.
- Heredity or genetics. The chance of stroke is greater in people with a family history of stroke.
Other risk factors include:
- Where you live. Strokes are more common among people living in the southeastern U.S. than in other areas. This may be because of regional differences in lifestyle, race, smoking habits, and diet.
- Temperature, season, and climate. Stroke deaths occur more often during extreme temperatures.
- Social and economic factors. There is some evidence that strokes are more common among low-income people.
What are the symptoms of a stroke?
A stroke is an emergency situation. It’s important to know the signs of a stroke and get help quickly. Call 911 or your local emergency number right away. Treatment is most effective when started right away.
Stroke symptoms may happen suddenly. Each person’s symptoms may vary. Symptoms may include:
- Weakness or numbness of the face, arm, or leg, usually on one side of the body
- Having trouble speaking or understanding
- Problems with vision, such as dimness or loss of vision in one or both eyes
- Dizziness or problems with balance or coordination
- Problems with movement or walking
- Fainting (loss of consciousness) or seizure
- Severe headaches with no known cause, especially if they happen suddenly
Other less common symptoms of stroke may include:
- Sudden nausea or vomiting not caused by a viral illness
- Brief loss or change of consciousness, such as fainting, confusion, seizures, or coma
- TIA, called a mini-stroke
A TIA can cause many of the same symptoms as a stroke. But TIA symptoms are passing. They can last for a few minutes or up to 24 hours. Call for medical help right away if you think someone is having a TIA. It may be a warning sign that a stroke is about to occur. But not all TIAs are followed by a stroke.
Get help FAST
FAST is an easy way to remember the signs of a stroke. When you see these signs, you will know that you need to call 911 fast. FAST stands for:
F – Face drooping. One side of the face is drooping or numb. When the person smiles, the smile is uneven.
A – Arm weakness. One arm is weak or numb. When the person lifts both arms at the same time, one arm may drift downward.
S – Speech difficulty. You may see slurred speech or difficulty speaking. The person can’t repeat a simple sentence correctly when asked.
T – Time to call 911. If someone shows any of these symptoms, call 911 right away. Call even if the symptom goes away. Make note of the time the symptoms first appeared.
How is a stroke diagnosed?
Your healthcare provider will take a complete health history and do a physical exam. You will need tests for stroke such as brain imaging and measuring the blood flow in the brain. Tests may include:
- CT scan of the brain. An imaging test that uses X-rays to take clear, detailed images of the brain. A brain CT scan can show bleeding in the brain or damage to brain cells caused by a stroke. It is used to find abnormalities and help find the location or type of stroke.
- MRI. This test uses a combination of large magnets, radiofrequencies, and a computer to make detailed images of organs and structures in the body. An MRI uses magnetic fields to find small changes in brain tissue that help to find and diagnose stroke.
- CTA (computed tomographic angiography). An X-ray image of the blood vessels. A CT angiogram uses CT technology to get images of blood vessels.
- MRA (magnetic resonance angiography). This test uses MRI technology to check blood flow through the arteries.
- Doppler sonography (carotid ultrasound). A test that uses sound waves to create pictures of the inside of your carotid arteries. This test can show if plaque has narrowed or blocked your carotid arteries.
The following heart tests may also be used to help diagnose heart problems that may have led to a stroke:
- Electrocardiogram (ECG). This test records your heart’s electrical activity. It shows any irregular heart rhythms that may have caused a stroke.
- Echocardiography. This test uses sound waves to create a picture of your heart. This test shows the size and shape of your heart. It can check if the heart valves are working properly. It can also see if there are blood clots inside your heart.