Maryann Bauman, M.D.
Chair, Cryptogenic Stroke Oversight Committee, American Stroke Association
For purposes of more effective treatment and prevention, it’s critical to understand the implications and possible causes of a cryptogenic stroke.
Stroke is the fifth-leading cause of death for Americans and a leading cause of long-term, severe disability. Your risk for stroke goes up based on several factors:
- High blood pressure
- High blood cholesterol
- Unhealthy eating habits
- Being overweight
- Lack of exercise
Understanding the cryptogenic strokes
There are two types of strokes: ischemic and hemorrhagic. An ischemic stroke occurs when there is a blockage within a blood vessel supplying blood to the brain. A hemorrhagic stroke happens when a weakened blood vessel breaks, causing bleeding in the brain. Ischemic strokes are far more common. In fact, 87 percent of strokes are ischemic.
While doctors usually look for a cause of each stroke, the reason for the blockage is unclear in about 200,000 of the nearly 690,000 ischemic strokes that happen every year. When the cause is not found before the patient is discharged from the hospital, the stroke is classified as cryptogenic.
Such strokes are concerning because if we don’t know why the stroke occurred, we don’t know how to best treat it to decrease the chance of another one. The possibility of a second stroke is very troubling because a second stroke usually is more severe than the first. And 25 percent of strokes happen to people who have had a previous one. That’s one in four.
Considering the potential causes
Patients and family members should suggest that their doctors work together to find the cause of a stroke that is labeled cryptogenic and ensure that extensive testing is done. Some of the causes to consider include:
- Atrial fibrillation (also known as AF or AFib): This is a specific type of irregular heartbeat. AFib is a major stroke risk factor that can be difficult to find but may be detected by monitoring the heart’s rhythm over time. There are several types of heart monitors, including the holter monitor, mobile continuous outpatient telemetry and implantable cardiac monitor.
- Patent foramen ovale: This is a hole between the heart’s chambers that is normal in an unborn baby and usually closes naturally by early childhood. In some people, the hole fails to close. A blood clot could pass through the hole and travel to the brain, causing a stroke.
- Large artery atherosclerosis: This is the term for plaques clogging large blood vessels that can rupture, causing clots that can block arteries in the brain.
It is important for health care providers to work together with patients and their families to help unveil the stroke mystery. When cardiologists, neurologists, primary care physicians and other health care professionals work together, it ensures that patients receive the most thorough care to help prevent another stroke.