Understanding a Stroke

What is Stroke?

A stroke is a “brain attack”. It can happen to anyone at any time. It occurs when blood flow to an area of brain is cut off. When this happens, brain cells are deprived of oxygen and begin to die. When brain cells die during a stroke, abilities controlled by that area of the brain such as memory and muscle control are lost.

How a person is affected by their stroke depends on where the stroke occurs in the brain and how much the brain is damaged. For example, someone who had a small stroke may only have minor problems such as temporary weakness of an arm or leg. People who have larger strokes may be permanently paralyzed on one side of their body or lose their ability to speak. Some people recover completely from strokes, but more than 2/3 of survivors will have some type of disability.

Different Types of Stroke’s: 

There are two types of stroke, hemorrhagic and ischemic.

Hemorrhagic strokes are less common, in fact only 15 percent of all strokes are hemorrhagic, but they are responsible for about 40 percent of all stroke deaths.  A hemorrhagic stroke is either a brain aneurysm burst or a weakened blood vessel leak. Blood spills into or around the brain and creates swelling and pressure, damaging cells and tissue in the brain. There are two types of hemorrhagic stroke called intracerebal and subarachnoid.

Ischemic stroke occurs when a blood vessel carrying blood to the brain is blocked by a blood clot. This causes blood not to reach the brain. High blood pressure is the most important risk factor for this type of stroke. Ischemic strokes account for about 87% of all strokes. An ischemic stroke can occur in two ways.

Embolic Stroke  a blood clot or plaque fragment forms somewhere in the body (usually the heart) and travels to the brain. Once in the brain, the clot travels to a blood vessel small enough to block its passage. The clot lodges there, blocking the blood vessel and causing a stroke. About 15% of embolic strokes occur in people with atrial fibrillation (Afib). The medical word for this type of blood clot is embolus.

Thrombotic Stroke:  is caused by a blood clot that forms inside one of the arteries supplying blood to the brain.  This type of stroke is usually seen in people with high cholesterol levels and atherosclerosis. The medical word for a clot that forms on a blood-vessel deposit is thrombus.

Two types of blood clots can cause thrombotic stroke: large vessel thrombosis and small vessel disease.

Large Vessel Thrombosis

The most common form of thrombotic stroke (large vessel thrombosis) occurs in the brain’s larger arteries. In most cases it is caused by long-term atherosclerosis in combination with rapid blood clot formation. High cholesterol is a common risk factor for this type of stroke.

Small Vessel Disease

Another form of thrombotic stroke happens when blood flow is blocked to a very small arterial vessel (small vessel disease or lacunar infarction). Little is known about the causes of this type of stroke, but it is closely linked to high blood pressure.

What is a TIA?

When blood flow to part of the brain stops for a short period of time, also called transient ischemic attack (TIA), it can mimic stroke-like symptoms. These symptoms appear and last less than 24 hours before disappearing. While TIAs generally do not cause permanent brain damage, they are a serious warning sign that a stroke may happen in the future and should not be ignored.

TIAs are usually caused by one of three things:

  1. Low blood flow at a narrow part of a major artery carrying blood to the brain, such as the carotid artery.
  2. A blood clot in another part of the body (such as the heart) breaks off, travels to the brain, and blocks a blood vessel in the brain.
  3. Narrowing of the smaller blood vessel in the brain, blocking blood flow for a short period of time; usually caused by plaque (a fatty substance) build-up.

Please contact your Doctor with any concerns you may have.