AAMC Magazine

Fall 2005

A Stroke Primer

What It is and How It Affects the Whole Body

Most of us know someone who has experienced a stroke. But we are less likely to understand the many different ways people may be affected. Some strokes are mild, and some are almost totally debilitating. What causes the very different consequences seen in stroke victims, and how much do health care providers know about the effects of a stroke on the human brain?

“The most common cause of stroke is carotid artery disease. But with screenings, many strokes can be prevented.”
Jon Hupp, M.D.

“We see a broad range of symptoms in stroke victims, depending on the area of the brain that is affected and the extent of the injury,” said AAMC neurologist Damanhuri Alkaitis, M.D.

Stroke occurs when a blocked or burst blood vessel interrupts blood flow to the brain. This interruption prevents brain cells from getting oxygen and nutrients, and nerve cells in the affected part of the brain stop functioning and die. These nerve cells control particular parts of the body, so when they can’t function well the body can’t either.

Mark Peeler, M.D., a vascular surgeon at AAMC, said that brain tissue lost during a stroke cannot be regenerated.

“All of the brain is fed by blood vessels, and when we lose the blood flow we lose that part of the brain permanently. If enough of the brain is lost we lose the functions that brain controls,” said Dr. Peeler.

Types of stroke

Strokes are classified into two categories, ischemic and hemorrhagic. Ischemic strokes, which account for 80 percent of all strokes, are caused when blood vessels in the brain or neck become narrow or clogged. Fatty deposits lining the walls of blood vessels may block blood from flowing freely. Clots may develop at the site of the deposit or a traveling particle may be too large to pass through the narrowed blood vessel. Ischemic strokes may have warning signs such as loss of strength or sensation, problems with speech, or changes in vision or balance.

Hemorrhagic strokes, which account for 15-20 percent of all strokes, are caused by bleeding in the brain or in the spaces between the brain and the skull. Bleeding comes from weakened areas in vessels called aneurysms (blood-filled pouches that can rupture), or from aging blood vessels deep in the brain that begin to bleed. The symptoms of a hemorrhagic stroke tend to appear suddenly, and often there are no warning signs.

Either kind of stroke can affect people in a variety of ways. Although the consequences of a stroke aren’t always predictable—they depend on the type of stroke and how extensively and where brain cells are damaged—having a stroke may influence a person’s behavior and emotions, motor activity, senses and hearing and speech, among other things.

After a stroke, a person’s thought patterns and emotional reactions may be different than they were before. That’s because parts of the brain produce emotions, just as other parts control movement. Stroke victims may experience moodswings or cry easily, and memory may be affected. As people struggle to adapt to impairment and try to regain function, they may feel depressed as well.

Physical limitations may be another result of a stroke. If brain cells that influence mobility and awareness are damaged, people may lose feeling in parts of their bodies like the arms or legs. Or they may have trouble sensing or moving one side of the body, usually the opposite side from the part of the brain where the stroke occurred.

Because a stroke can affect parts of the brain that control perception, people may have trouble seeing, touching, and recognizing everyday objects. They may be prone to falls because they are less able to judge distances, and their vision may be impaired.

Many stroke victims struggle to recognize and produce words, or to speak intelligibly. They may also have trouble saying what they mean (a condition that is called aphasia). Aphasia is most common after a stroke on the left side of the brain, and it makes it difficult for people to read and write as well as listen and speak.

Rehab technique improving

Although the effects of stroke can be limiting, there is good news. Healthcare providers have more information than ever about how to rehabilitate people from strokes. More than 4.7 million Americans are stroke survivors, and physicians are developing new and better methods of helping them regain function.

“Stroke rehabilitation is improving all the time,” said Brian Kahan, M.D., an AAMC specialist in Physical Medicine and Rehabilitation. “We are using techniques such as constraint-induced therapy, which restrains a non-affected body part and encourages use of the side of the body affected by a stroke.”

“And as risk factors for stroke (including high blood pressure, heart disease, smoking and high cholesterol) are better understood and better treated, more and more strokes are preventable,” said cardiologist Jonathan Altschuler, M.D.

“The most common cause of stroke is carotid artery disease. But with screenings, many strokes can be prevented,” said vascular surgeon Jon Hupp, M.D.

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