What causes a stroke can vary, depending on whether the stroke is ischemic or hemorrhagic. An ischemic stroke involves a lack of blood to the brain due to a narrowed or blocked blood vessel. This is most likely caused by an embolism, thrombosis, or stenosis. Hemorrhagic strokes generally involve bleeding in the brain, which can occur with blood vessel breakage, a bleeding aneurysm, or head trauma.
What Causes a Stroke?A stroke (known medically as a cerebrovascular accident or CVA) occurs when brain tissue is damaged. There are two main types of strokes: ischemic strokes and hemorrhagic strokes. An ischemic stroke occurs when there is a lack of oxygen- or nutrient-rich blood to a part of the brain. A hemorrhagic stroke results from bleeding in the brain. For each type of stroke, the specific causes can vary.
Causes of Ischemic Stroke
The most common type of stroke is an ischemic stroke. Up to 80 percent of stroke cases are ischemic strokes. With this stroke, not enough essential oxygen- and nutrient- rich blood is able to get to certain parts of the brain for a long enough period of time that brain tissue is damaged. This lack of blood supply occurs because a blood vessel becomes severely narrowed or blocked.
There are several reasons why a blood vessel in the brain may become severely narrowed or blocked. The two most common causes are an embolism and thrombosis. An embolism occurs when a blood clot or other tissue (called an embolus) from another part of the body, such as the heart, moves through the blood into the neck or brain. Thrombosis occurs when a blood clot (known as a thrombus) forms within a blood vessel of the brain or neck. Unlike an embolism, with thrombosis, the blood clot does not break free.
A blood vessel can also become narrowed or blocked through stenosis. Stenosis is severe narrowing of an artery in or leading to the brain. In most cases, a plaque buildup causes stenosis.