Stroke: There's More Than One Kind
A stroke occurs when blood flow to the brain is blocked. Oxygen-rich blood is carried to the brain through 4 major arteries:
2 Carotid: one on each side of the front of the neck
2 Vertebral: one on each side of the back of the neck
These four arteries form a connecting circle inside the brain called the Circle of Willis. Smaller arteries branch off the circle, supplying blood to the brain. If one of the major arteries is blocked, the brain continues to receive blood through the remaining open arteries.
A stroke, or “brain attack”, can happen to anyone at any time. When blood flow to an area of brain is cut off, brain cells can’t get 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 it occurs in the brain and how much of the brain is damaged. Someone who had a small stroke may have only minor problems, such as temporary weakness of an arm or leg. Others 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.
Types of Stroke
Hemorrhagic: occurs from bleeding in the brain, such as with a ruptured aneurysm:
Blood spills into the brain and creates swelling and pressure, damaging cells and tissue
15% of all strokes are hemorrhagic but responsible for 40% of all stroke deaths
Ischemic: occurs when a blood vessel carrying blood to the brain is blocked, depriving the brain cells of oxygen:
High blood pressure is the most important risk factor
Accounts for 87% of all strokes
Usually caused by a blood clot (see below)
Embolic: a blood clot or plaque fragment (see below) forms somewhere else in the body and travels to the brain:
Once in the brain, it travels to a blood vessel small enough to block its passage
About 15% occur in people with atrial fibrillation (a quivering or irregular heartbeat)
Thrombotic: caused by a blood clot that forms inside one of the arteries supplying blood to the brain.
Seen in people with high cholesterol levels and atherosclerosis (see below)
Transient Ischemic Attack (TIA) occurs when blood flow to part of the brain stops for a short period of time:
It can mimic stroke-like symptoms
These appear and last less than 24 hours before disappearing
They usually don’t cause permanent brain damage
They are a serious warning sign that a stroke may happen in the future and should not be ignored
Stroke symptoms: F.A.S.T.
Face Drooping: One side of your face droops or is numb. For example, a smile that is uneven or lopsided, or loss of tongue control on one side
Arm Weakness: One arm is weak or numb. For example, ask the person to raise both arms. Watch to see if one arm drifts downward
Speech: You are unable to speak, or your speech is slurred and hard to understand
Time: If the person shows any of these symptoms, even if the symptoms go away, call 9-1-1 and get them to the hospital immediately
Atherosclerosis and Plaque
Plaque is made up of fat, cholesterol, calcium, and other substances found in the blood
Over time, plaque hardens and narrows your arteries, causing atherosclerosis
This limits the flow of oxygen-rich blood to your heart, brain, and other parts of your body
Plaques can rupture. When they do, a blood clot can form on the plaque, blocking the flow of blood