What is a Stroke?

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Stroke is a sudden interruption of blood flow to the brain that causes brain injury and results in impairment or loss of some functions.

Most people have heard of “stroke” and likely know someone who has had one. In fact, the American Stroke Association’s current estimate puts the number of people who have a stroke each year at 12 million, with nearly 800,000 in the United States alone.

There are two main causes or types of stroke. One results from a blockage in an artery that delivers oxygen and nutrients to the brain. This type is called an “ischemic” stroke. The other type results from a rupture of a vessel (artery or vein) that causes bleeding into the brain and is called a “hemorrhagic” stroke.

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If brain cells do not get oxygen and nutrients (due to blockage or bleeding), the affected brain cells die and cannot function. Bleeding into the brain also prevents nerves from communicating with parts of the body and the functions they control.

As an injury to the brain, stroke can affect many vital functions and can sometimes even affect personality. Each area of the brain manages different functions (see illustration linked below), but sometimes there is overlap so that more than one location controls a function. Also, because each side of the brain controls movement of the opposite side of the body, damage to the left side (hemisphere) causes weakness on the right side of the body, and vice versa. 

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About three-quarters of stroke patients experience impairment, weakness or paralysis in their arms and hands. For many people, regaining function or strength in the arms and hands is the toughest part of stroke recovery because upper-body function tends to recover the most slowly.

In addition, stroke can cause mental (cognitive) impairment, including aphasia. Aphasia is a communication disorder that impairs the ability to speak and understand language, and also affects the ability to read and write. Approximately 20 percent of stroke patients have aphasia.

Even with the best medical care, about 80 percent of the people who have had a stroke will continue to have weakness or other physical limitations. These limitations can make it difficult to do daily activities, walk or communicate with others.

Still, there is hope. A person who has ongoing functional limitations after a stroke can seek help at a rehabilitation hospital or rehabilitation clinic. 

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Get treatment immediately! Getting to the hospital right away gives doctors the chance to use medicine that can clear the blockage, or surgically remove a blockage from the vessels supplying the brain with blood and oxygen. These treatments work better the faster medical treatment is given. This time period is called the “acute phase” of a stroke.

Following treatment, the nature of the blockage determines whether passages are completely cleared. They may dissolve on their own or some blockage may remain.

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After the injury, the brain is actively trying to heal itself and “rewire” how it controls function. Typically, the optimal time is within the first three months after the injury, but the treating doctor should determine when a patient should begin rehabilitation.

Rehabilitation hospitals or centers have specialized therapists — physical therapists (PTs), occupational therapist (OTs), speech therapists (also called speech-language pathologists (SLPs) and others who can provide a variety of exercise therapies and treatments to help people who have had a stroke to recover function. Such therapies help stroke patients recover strength, balance and skills for doing daily activities (like dressing or making a meal). After a course of therapy, many can walk again, communicate and live independently. Some can even return to driving a car or go back to work.

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There are also new treatments and technologies being studied with the potential to help people recover from stroke — use of robots to assist with exercise, techniques to stimulate recovery of brain function, new kinds of drugs and even stem cell treatments. (Every cell in the human body has stem cells. When certain types of stem cells are inserted into the brain, they can boost the brain’s natural healing properties.)

These new treatments are all being tested by research scientists at large rehabilitation research hospitals. Hopefully, these new treatments will be effective, helping even more people recover from a stroke in the future.

Find more information on recovery from stroke.

Richard L. Harvey, MD, is a leading expert in understanding and treating stroke. He is the Clinical Chair of the Brain Innovation Center at Shirley Ryan AbilityLab, the leading rehabilitation hospital. In his practice, he integrates rehabilitation medicine with scientific research, including a focus on stroke-related research designed to improve patient outcomes.