What is stroke?

Stroke is a common condition caused by abnormal brain blood vessels. Someone in the United States has a stroke every 40 seconds. Stroke kills more than 130,000 Americans each year and many people who survive become temporarily or permanently disabled.

There are two major types of stroke.  The first and more common type is ischemic stroke. This type of stroke happens when blood flow through the artery that supplies oxygen-rich blood to the brain becomes blocked.

The second major type of stroke is called hemorrhagic stroke. In this type of stroke an artery in the brain leaks blood or ruptures and floods the brain tissue with blood. The leaked blood puts too much pressure on brain cells, which damages them. There are 2 subtypes of hemorrhagic stroke: 1) intracerebral hemorrhage, which occurs when an artery in the brain bursts, flooding the surrounding tissue with blood and 2) subarachnoid hemorrhage, which occurs when there is bleeding in the area between the brain and the thin tissues that cover it.

In addition to the two major types of stroke, there is another type called a transient ischemic attack (TIA) also known as a mini-stroke. In this type blood flow to the brain is blocked for only a short time—usually no more than 5 minutes. This limits the damage that is done to the brain.


What causes stroke?

Ischemic stroke occurs when the arteries that supply oxygen to the brain become narrowed or blocked, reducing or completely stopping blood supply to the brain. Ischemic strokes are often caused by a blood clot or debris of tissue carried by the blood. Hemorrhagic stroke on the other hand can be caused by uncontrolled high blood pressure (hypertension), anticoagulants, and/or weak spots in the blood vessel walls (aneurysms). Risk factors of stroke include both lifestyle factors (weight, diet, physical activity, smoking and alcohol consumption, etc) and medical conditions (high cholesterol, high blood pressure, diabetes, etc).


Diagnosing stroke

It is important to recognize the signs of stroke early. The sooner treatment begins, the smaller the damage to the brain tissue will be. Some of the main signs of stroke include speech difficulty, arm weakness, and a drooping face. See “Additional resources” for more information on stroke signs. It is very important to dial 911 as soon as you recognize the signs of stroke in yourself or another person.

Your doctor will diagnose your stroke based on your signs and symptoms, and your medical history. Common diagnostic tools for stroke are medical imaging tools such as Brain Computed Tomography, Magnetic Resonance Imaging, and Carotid Ultrasound.


How is stroke related to aphasia?

Stroke is the most common cause of aphasia. When either ischemic or hemorrhagic stroke result in brain tissue damage in areas of the brain that are of particular importance to speech and language, a person may develop aphasia. For most people, these areas are in the left side of the brain, although the right side of the brain is also involved in aspects of speech and language production. Depending on the size of brain tissue damaged during stroke, the loss of speech and language abilities may be temporary or long-term. Size of brain damage also affects how quickly and how successfully a person can improve with speech therapy.


Additional resources