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More about stroke

Stroke information

More than 795,000 Americans will have a stroke—or brain attack—this year, and 133,000 cases will be fatal. Stroke is the fifth leading cause of death in the United States. It is a common misconception that stroke only occurs in the elderly. Recent studies documenting an increase in stroke in the young suggest that one in five patients presenting with stroke are under the age of 55.

A stroke happens when blood and oxygen flow to the brain is stopped or interrupted due to either a blockage in a blood vessel or a ruptured blood vessel. This loss of oxygen will cause damage to the brain. The two major kinds of stroke are ischemic stroke and hemorrhagic stroke.

Ischemic stroke

Ischemic stroke occurs when a blood vessel that supplies blood to the brain is blocked by a blood clot, preventing oxygen from reaching brain cells.  The resulting damage to the brain is the ischemic stroke.  This is the most common kind of stroke. There are different causes for ischemic stroke, some of which include:

  • Atherosclerosis: Atherosclerosis develops when fatty deposits (called cholesterol plaque) build up over time in the walls of larger blood vessels. Eventually, the buildup causes the blood vessel to narrow. Blood flow in these vessels is decreased much like a clogged pipe will slow the flow of water in a drain. A blood clot can then form on the surface of the plaque and completely block blood flow to an area of brain, resulting in a stroke.
  • Cardio embolism: A clot forms in the heart (for example, on a damaged wall or valve), travels to the brain, becomes lodged in a blood vessel and affects the blood flow in that vessel causing stroke. Below are some of the more common reasons blood clots form in your heart.
    • Atrial fibrillation - a specific type of irregular heart beat causes clots to form in one of the upper chambers of the heart (left atrium).
    • Heart valve abnormality - a blood clot forms on an artificial or damaged heart valve.
    • Damage to heart wall - a heart attack or an enlarged heart causes clots to form along the wall of the heart, especially in the left ventricle.
    • Patent foramen ovale - a valve-like hole in the heart (a common heart defect) sometimes leads to an increased risk of stroke.
  • Small vessel disease: A lacunar stroke occurs when the smallest vessels deep within the brain become blocked with plaque. It is similar to atherosclerotic stroke, except it affects small vessels instead of large vessels. 

Transient ischemic attack

About 10 percent of people have a warning sign before an ischemic stroke. This is called a transient ischemic attack (TIA).

A TIA is a temporary interruption of blood flow to a part of the brain. The signs and symptoms of a TIA are the same as those experienced with a stroke, but they last for a shorter period–usually less than one hour–and then disappear, without leaving permanent effects.

Because TIAs are temporary and the symptoms may resolve quickly, it is easy to ignore them or to believe that the problem has disappeared. It is dangerous to ignore TIAs, however, because the underlying problem that caused the TIA continues to exist. It is extremely important to understand that a TIA requires immediate medical attention, as they are often early warning signs of a more serious and debilitating stroke to come.

Hemorrhagic stroke

A hemorrhagic stroke occurs when a brain blood vessel bursts and bleeds, causing blood to leak into or around brain tissue. As it collects, the pool of blood puts pressure on the brain and irritates brain tissue.

The two different types of hemorrhagic stroke are:

  • Intracerebral hemorrhage: A damaged or weakened blood vessel breaks, causing a mass of blood to collect inside your brain. Causes of intracerebral hemorrhage include:
    • high blood pressure that damages small blood vessels
    • arteriovenous malformation (AVM), which is an abnormally-formed group of thin-walled blood vessels, often present since birth, that ruptures causing intracerebral hemorrhage
    • amyloid angiopathy, which is a condition found in the elderly that affects the small superficial blood vessels of the brain causing them to weaken with risk of rupture
    • the use of blood-thinning medications, including warfarin (Coumadin®), aspirin, clopidogrel (Plavix®), dipyridamole (Aggrenox®), which may increase the severity of a hemorrhage.
  • Subarachnoid hemorrhage: A blood vessel at the base of the brain ruptures and bleeds, causing blood to collect in the space between the brain and skull, called the subarachnoid space. This is most commonly caused by an aneurysm, which is a balloon-shaped weakness in the wall of a blood vessel.

Through prevention, education, treatment and rehabilitation, Allina Health is working to lower the incidence and improve the recovery from all types of stroke.