A stroke is a disturbance in the blood flow within the vessels affecting the arteries leading to and within the brain. Most strokes occur when the brain is deprived of oxygen-rich blood due to a blockage of a blood vessel supplying the brain with blood. Some strokes are caused by bleeding into or around the brain.
The most common stroke (thrombotic) is caused by a sudden blockage of blood flow to the brain, thus sharply reducing the amount of oxygen it receives to function and survive. Without oxygen or nutrients, brain cells die quickly, with little chance of recovering function. Thrombotic stroke commonly results from partial or complete blockage of blood flow in the major arteries in the neck.
The narrowing can progress to a complete blockage. Sometimes, a blood clot adhering to the plaque breaks free and is carried by the blood (as an Embolus – Figure 2B) to block circulation in a smaller artery in the brain.
Sometimes a person experiences a series of “mini strokes” called transient ischemic attacks (TIAs) before a catastrophic stroke occurs. TIAs result from brief reductions of blood flow to the brain. Symptoms of TIA include weakness and numbness, and difficulty with speech or vision that resolve within minutes or within 24 hours. TIAs can be treated to prevent a major stroke.
Finally, a diseased blood vessel can bleed into the brain. This is called a Hemorrhagic Stroke (about 17% of all strokes). Hemorrhagic Strokes are most often caused by uncontrolled high blood pressure.
Treatment & Prevention
If you are over 55, male, African American, Hispanic or Asian/Pacific Islander, or have a family history of stroke, your chances of having a stroke are increased. But you can lower your risk of a stroke by following the National Stroke Association’s Stroke Prevention guidelines:
- Keep your blood pressure under control. High blood pressure is a leading cause of stroke. Consult your doctor if the higher number (your systolic blood pressure) is usually about 140 or if the lower number (your diastolic blood pressure) is usually over 90.
- Find out if you have atrial fibrillation (also called AF). AF is an irregular heartbeat that can allow blood to collect in the chambers of your heart. If you have AF, work with your doctor to manage it.
- Stop smoking. Smoking doubles the risk for stroke.
- Drink alcohol in moderation. Alcohol is a drug and is harmful if taken in large doses.
- Control your cholesterol number. High cholesterol often can be controlled with diet and exercise. Some people need medication to control it.
- If you are diabetic, control your diabetes. Diabetes puts you at an increased risk for stroke.
- Include exercise in the activities you enjoy in your daily routine. As little as 30 minutes a day of exercise can improve your health in many ways, and may reduce your risk for stroke.
- Enjoy a lower sodium (salt), lower fat diet. Keep your blood pressure in the normal range by cutting down on sodium and fat in your diet.
- Ask your doctor if you have circulation problems. Fatty deposits can block the arteries which carry blood from your heart to your brain. This kind of blockage can cause stroke. Find out if you have sickle cell disease, severe anemia, or other diseases that can cause stroke.
If you or a person you know develops any of the following symptoms of a stroke, dial 911 for emergency assistance and immediate transportation to an emergency room. The sooner you receive treatment, the less likely you will die or become disabled. Stroke symptoms include:
- Temporary or sustained loss of consciousness
- Slurred speech
- Weakness of a limb
- Lack of facial movement (usually on one side)
- Severe headache with no known cause
- Your quick action can save a life and often will prevent serious disability
Stroke Educational Flyer
National Stroke Association
American Stoke Association
National Institute of Neurological Disorders and Stroke
Brain Aneurysm Foundation