Banner Health Services  

Understanding Stroke

F.A.S.T. Stroke Campaign  

As a leading provider of stroke care, Banner Health understands that education about stroke is critical. There are several types of stroke and successful treatment depends on differentiating between them.

Do you know the warning signs of stroke? right arrow

What is a stroke?
During a stroke, blood stops flowing to the part of the brain. The affected area is damaged from a lack of oxygen. Within minutes, skills such as reasoning, speech, and arm or leg movement may be lost. The severity of the stroke depends on two things: which part of the brain was affected and how much tissue was damaged.

Different types of stroke:

Transient ischemic attack (TIA)
Up to 15 percent of strokes are signaled by one of these “warning strokes.” Symptoms are the same as those of a stroke, but they last less than a day; about 75 percent of them last less than five minutes. A TIA can occur days or months before a major stroke does, but risk of stroke is highest within 48 hours of a TIA. That’s why it’s important to seek immediate medical care for a possible TIA.

Ischemic stroke
An ischemic stroke occurs when a blood vessel that supplies the brain becomes blocked or "clogged" and impairs blood flow to part of the brain. The brain cells and tissues begin to die within minutes from lack of oxygen and nutrients. The area of tissue death is called an infarct. About 87 percent of strokes fall into this category. Ischemic strokes are further divided into two groups, including the following:
  • Thrombotic stroke:
    Thrombotic strokes are strokes caused by a thrombus (blood clot) that develops in the arteries supplying blood to the brain. This type of stroke is usually seen in older persons, especially those with high-cholesterol levels and atherosclerosis (a build-up of fat and lipids inside the walls of blood vessels).
    • Sometimes, symptoms of a thrombotic stroke can occur suddenly and often during sleep or in the early morning. At other times, it may occur gradually over a period of hours or even days. This is called a stroke-in-evolution.
    • Thrombotic strokes may be preceded by one or more "mini-strokes," called transient ischemic attacks, or TIA.
  • Lacunar Infarct:
    A type of stroke that occurs in the small blood vessels in the brain is called a lacunar infarct. Lacunar infarctions are often found in people who have diabetes or hypertension (high blood pressure).
  • Embolic stroke:
    Embolic strokes are usually caused by an embolus (a blood clot that forms elsewhere in the body and travels through the bloodstream to the brain). Embolic strokes often result from heart disease or heart surgery and occur rapidly and without any warning signs. About 15 percent of embolic strokes occur in people with atrial fibrillation, a type of abnormal heart rhythm in which the upper chambers of the heart do not beat effectively.

Hemorrhagic stroke:
Hemorrhagic strokes occur when a blood vessel that supplies the brain ruptures and bleeds. When an artery bleeds into the brain, brain cells and tissues do not receive oxygen and nutrients. In addition, pressure builds up in surrounding tissues and irritation and swelling occur. About 13 percent of strokes are caused by hemorrhage. Hemorrhagic strokes are divided into two main categories, including the following:
  • Intracerebral hemorrhage:
    Intracerebral hemorrhage is usually caused by hypertension (high blood pressure), and bleeding occurs suddenly and rapidly. There are usually no warning signs and bleeding can be severe enough to cause coma or death.
  • Subarachnoid hemorrhage:
    Subarachnoid hemorrhage results when bleeding occurs between the brain and the meninges (the membrane that covers the brain) in the subarachnoid space. This type of hemorrhage is often due to an aneurysm or an arteriovenous malformation (AVM).
    • An aneurysm is a weakened, ballooned area on an artery wall and has a risk for rupturing. Aneurysms may be congenital (present at birth), or may develop later in life due to such factors as hypertension or atherosclerosis.
    • An AVM is a congenital disorder that consists of a disorderly tangled web of arteries and veins. The cause of AVM is unknown.

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