HealthWise KnowledgeBase
Stroke
Cause
Causes of ischemic stroke
An ischemic stroke is caused by a blood clot that blocks blood flow to the brain.
- A blood clot can form in an artery that supplies blood to the brain.
- Blood clots usually form in arteries damaged by plaque buildup, which is a process called Reference atherosclerosis Opens New Window.
- Long-term high blood pressure or diabetes may damage smaller blood vessels in the brain, causing a clot to form within the blood vessels and block blood flow.
- A blood clot can form in another part of the body (often the heart) and travel through the bloodstream to the brain. For example, clots may form:
- After a heart attack.
- As a result of other problems that change the blood flow through the heart. These conditions include abnormal heart rhythms (especially Reference atrial fibrillation Opens New Window), heart valve problems, Reference patent foramen ovale Opens New Window, Reference atrial septal defects Opens New Window, and Reference heart failure Opens New Window.
Low blood pressure may also cause an ischemic stroke, although this is less common. Low blood pressure results in reduced blood flow to the brain. It may be caused by narrowed or diseased arteries, a heart attack, a large loss of blood, or a severe infection.
Some surgeries (such as endarterectomy) or other procedures (such as carotid artery stenting) that are used to treat narrowed carotid arteries may cause a blood clot to break loose, resulting in a stroke.
Causes of hemorrhagic stroke
A hemorrhagic stroke is caused by bleeding in or around the brain.
- Bleeding inside the brain itself (intracerebral hemorrhage, or ICH) may be a result of long-term high blood pressure.
- Bleeding in the space around the brain (subarachnoid hemorrhage, or SAH) may be caused by a ruptured Reference aneurysm Opens New Window or uncontrolled high blood pressure.
Other less common causes include head or neck injuries, certain diseases, and radiation treatment for cancer in the neck or brain.
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