Stenosis
A third
ischemic stroke cause involves a type of artery narrowing known as stenosis. This narrowing most often occurs from the buildup of
plaque from
atherosclerosis. Over time, this narrowing can completely block a brain artery.
Hemorrhagic Stroke Causes
Bleeding into the brain (or the spaces surrounding the brain) causes the second main type of
stroke, called a hemorrhagic stroke. In a healthy, functioning brain, brain cells do not come into direct contact with blood. If an artery in the brain breaks, blood moves out into the surrounding tissue, causing damage. Hemorrhagic strokes account for approximately 20 percent of all strokes.
Common hemorrhagic stroke causes include:
- Blood vessel breakage
- Aneurysm
- Arteriovenous malformation
- Trauma
- Tumor or cancer.
Blood Vessel Breakage
Bleeding can also occur when arterial walls break open. Plaque-encrusted artery walls eventually lose their elasticity and become brittle, thin, and prone to cracking.
Hypertension, commonly known as
high blood pressure, increases the risk that a brittle artery wall will give way and release blood into the surrounding brain tissue. In fact, high
blood pressure is the most common underlying cause of hemorrhagic stroke.
Aneurysm
One common hemorrhagic stroke cause is a bleeding aneurysm, which is a weak or thin spot on an artery wall. Over time, these weak spots stretch or balloon out under high blood pressure. The thin walls of these ballooning aneurysms can rupture and spill blood into the space surrounding brain cells.
Arteriovenous Malformation
A person with an arteriovenous malformation (AVM) also has an increased risk of hemorrhagic stroke. AVMs are a tangle of defective blood vessels and capillaries within the brain that have thin walls, which can rupture.
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