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Neurology and Neuroscience
Causes of Stroke
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Causes of Ischemic and Hemorrhagic Stroke
What Causes a Stroke?
Stroke occurs when a blood vessel is blocked by a clot (an ischemic stroke) or when a blood vessel in the brain ruptures (hemorrhagic stroke). Larger strokes can cause swelling and compression in the brain.
With both types of stroke, the flow of oxygen-rich blood is cut off to a part of the brain, and brain cells die. As a result, a person suffers neurological deficits related to the part of the brain that is damaged.
Most of the 750,000 strokes that occur in the United States each year are ischemic strokes (88 percent), but hemorrhagic strokes are more likely to be fatal.
What is an Ischemic Stroke?
Ischemic strokes are often the result of carotid artery disease, a buildup of plaque inside walls of the arteries in the neck, which can restrict or block the flow of blood to the brain.
Additionally, blood clots can develop on the plaque, which can break loose and block brain arteries, causing a stroke.
People with high blood pressure, heart disease or diabetes – or those that smoke, are obese or have a family history of stroke – are at greater risk of developing carotid artery disease.
What is a Hemorrhagic Stroke?
A hemorrhagic stroke occurs when a blood vessel in the brain ruptures.
Most hemorrhages occur are caused by high blood pressure, which can lead to rupture of tiny arteries deep in the brain.
In another type of hemorrhage called subarachnoid hemorrhage, the rupture is at the site of an aneurysm, a bulge that develops in a weak area of an artery's wall.
Less often, the rupture occurs where there is an abnormal connection between arteries and veins (arteriovenous malformation or AVM). This congenital abnormality may be present at birth, but it is usually only identified when symptoms develop.
Both aneurysms and AVMs can be surgically repaired if they are identified before a stroke occurs.
NewYork-Presbyterian Hospital is a leader in the treatment and research of stroke. Learn more about our stroke centers.
