Campus Life

The Medical Minute: Brain attack

By John Messmer
Penn State Family and Community Medicine
Penn State Milton S. Hershey Medical Center
Penn State College of Medicine

About 700,000 people have strokes annually in the United States, yet most people do not know even one symptom of a stroke. To understand strokes, it helps to compare them to another common disease of circulation. A heart attack occurs when the blood supply to the heart is impaired just as a stroke results when the blood supply to part of the brain is interrupted. For that reason, a stroke has been called a "brain attack."

Blood carries oxygen and nutrients to the brain via two carotid arteries in the neck and two vertebral arteries that travel inside the spinal column. When these arteries and all their branches are free of disease, we can think, speak, see, hear, walk and use our arms with normal balance and coordination. When an artery is clogged by cholesterol or a blood clot or if it ruptures, blood flow to part of the brain is affected, and the function of that part of the brain weakens or stops.

There are two general types of stroke: ischemic and hemorrhagic. The term "ischemia" comes from the Greek for "restriction" and "blood." An ischemic stroke occurs when the supply of blood is cut off. Hemorrhagic stroke results from bleeding, usually from a weak spot in an artery.

If blood supply is not returned to the area soon, usually within a couple hours, that part of the brain dies. If a large artery is affected, a large part of the brain can die; smaller artery strokes damage smaller areas of the brain. In some cases, the area of damage is so small, the person does not even know a stroke occurred. They can have multiple small strokes over years until the cumulative effect of the damage becomes apparent.

Sometimes the blood supply is reduced or cut off for a short time resulting in a loss of function, but then the blood supply returns. Perhaps the body's clot-dissolving chemicals removed a blood clot or a narrowed area relaxed after going into spasm. The neurologic deficit that occurred will resolve, usually within 24 hours. This is called a transient ischemic attack or TIA. Sometimes they are called "mini-strokes." Even though normal function returns, it is a major warning sign of brain attack, just as angina is a warning sign for a heart attack. Having a TIA carries about a 10 percent risk of a full stroke in the next 90 days, with the highest risk in the next week.

Most strokes are due to atherosclerosis, or hardening of the arteries. Causes of atherosclerosis include high blood pressure, diabetes, high cholesterol, smoking and lack of exercise. Obesity contributes to arterial disease by making blood pressure, diabetes and cholesterol worse but abdominal obesity defined as a waist size greater than 40 inches in men and 35 inches in women may be an independent risk for atherosclerosis.

Some strokes result from congenital weak areas in arteries that rupture. Others come from blood clots that develop elsewhere in the body and travel to the brain. Stroke risk also is greater for women on birth control pills and postmenopausal hormone replacement and migraine sufferers, but the degree of increased risk can be small or large depending on the person's general health status.

Atrial fibrillation, more common in people over 50, annually is responsible for more than 75,000 strokes due to blood clots. This is a condition in which the atria, the upper chambers of the heart, do not contract properly. Blood does not get pumped out of the atria efficiently and may form clots that can be move up to the brain. Other conditions associated with clots include severe heart failure, heart valve disease and blood clots from the legs that pass through the foramen ovale, an opening between the upper chambers of the heart that is supposed to close after birth.

Organizations dedicated to stroke research and public education on strokes, such as the National Institutes for Neurologic Diseases and Stroke at http://www.ninds.nih.gov/disorders/stroke/stroke.htm and the National Stroke Association at http://www.stroke.org list warning signs and symptoms of stroke. The scary thing for the average person is that many of the symptoms also are common to more benign problems.

Typically signs of a stroke develop suddenly. A symptom that develops over hours or days is probably not a stroke. Some of the warning signs for stroke are:

-- Sudden weakness in the face, arm or leg on one side of the body. Note that Bell's palsy, a benign condition, causes facial weakness, but a stroke typically has weakness in other areas in addition to the face.

-- Sudden confusion, difficulty speaking or understanding.

-- Sudden loss of vision in one or both eyes or sudden double vision.

-- Sudden difficulty walking or sudden dizziness or loss of balance. Note that a common benign cause of dizziness, an inner-ear problem, eases when motionless while it typically is persistent with a stroke.

-- Sudden, severe headache without a known cause.

-- Sudden, severe nausea or hiccups.

Women may have unique stroke symptoms:

-- Sudden face and limb pain.

-- Sudden generalized weakness.

-- Sudden chest pain, shortness of breath or palpitations.

Stroke risk is reduced the same way heart disease is: by regular exercise, cessation of smoking, control of weight and diabetes and lowering cholesterol and blood pressure. For people with high cholesterol, statin medications have been proven to reduce the risk significantly. Diabetics should try to keep their blood sugars in the normal range if possible and normal blood pressure is best.

Should any of the warning signs of brain attack develop, particularly in someone with risk factors, the best thing to do is call 911. Do not wait to see if it gets better. It is critical to get to a hospital capable of managing strokes so that treatment can begin within three hours of symptom development to increase the chance of saving brain tissue. Early diagnosis and treatment can restore blood flow or stop bleeding before damage becomes permanent or death occurs, but that means action when symptoms first develop.

Last Updated March 19, 2009

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