Cryptogenic Stroke

What is a Cryptogenic Stroke?

Patient entering Magnetic Resonance Imaging (MRI) scanner
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A cryptogenic stroke cannot be attributed to any specific cause after an extensive search for the most common causes, such as cardiac and other emboli, large or small artery thrombi or atherosclerosis. It’s estimated that 25 to 30 percent of ischemic strokes are cryptogenic. Studies suggest that the incidence of cryptogenic stroke is higher in African-Americans (two times more likely) and Hispanics (46 percent more likely).

What is Stroke?

Stroke is a disease that affects the arteries leading to and within the brain. It is the No. 5 cause of death and a leading cause of disability in the United States. A stroke occurs when a blood vessel that carries oxygen and nutrients to the brain is either blocked by a clot or bursts (or ruptures). When that happens, part of the brain cannot get the blood (and oxygen) it needs, so it and brain cells die.

Types of Stroke

Stroke can be caused either by a clot obstructing the flow of blood to the brain (called an ischemic stroke) or by a blood vessel rupturing and preventing blood flow to the brain (called a hemorrhagic stroke). A TIA (transient ischemic attack), or "mini stroke", is caused by a temporary clot. 

Effects of Stroke

The brain is an extremely complex organ that controls various body functions.  If a stroke occurs and blood flow can't reach the region that controls a particular body function, that part of the body won't work as it should. 

Risk Factors of Stroke

  • Age — The chance of having a stroke approximately doubles for each decade of life after age 55. While stroke is common among the elderly, a lot of people under 65 also have strokes.
  • Heredity (family history) — Your stroke risk may be greater if a parent, grandparent, sister or brother has had a stroke. 
  • Race — African-Americans have a much higher risk of death from a stroke than Caucasians do. This is partly because blacks have higher risks of high blood pressure, diabetes and obesity.
  • Sex (gender) — Each year, women have more strokes than men, and stroke kills more women than men. Use of birth control pills, pregnancy, history of preeclampsia/eclampsia or gestational diabetes, oral contraceptive use, and smoking, and post-menopausal hormone therapy may pose special stroke risks for women. 
  • Prior stroke, TIA or heart attack — The risk of stroke for someone who has already had one is many times that of a person who has not. Transient ischemic attacks are "warning strokes" that produce stroke-like symptoms but no lasting damage. TIAs are strong predictors of stroke. A person who's had one or more TIAs is almost 10 times more likely to have a stroke than someone of the same age and sex who hasn't. Recognizing and treating TIAs can reduce your risk of a major stroke. TIA should be considered a medical emergency and followed up immediately with a healthcare professional. If you've had a heart attack, you're at higher risk of having a stroke, too.


    American Heart Association. "What's at the heart of my cryptogenic stroke?

    American Stroke Association.

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