Why Does This Mysterious Stroke Have No Apparent Cause?

What you need to know about cryptogenic stroke
Why Does This Mysterious Stroke Have No Apparent Cause?

When a person has a stroke, treatment usually depends on what caused a problem with blood flow to the brain. In some cases, despite an extensive workup, the cause of the stroke may not be evident, or “cryptogenic” (of unknown origin).

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While this can be frustrating, ongoing research is helping us understand this medical mystery, offering new methods of detection and treatment.

Neurologist Irene Katzan, MD, and cardiologist Walid Saliba, MD, explain what you need to know about cryptogenic stroke, and how to prevent strokes in general.

How many of all strokes are of unknown origin?

Ischemic strokes account for 85 percent of all strokes. These strokes happen when an artery to the brain becomes blocked, usually by a blood clot. About 25 percent of ischemic strokes are cryptogenic, meaning that typical tests have not found a cause.

The other 15 percent of all strokes are considered hemorrhagic strokes, which happen when a weakened blood vessel ruptures in the brain.

What common remedy treats strokes of unknown causes?

While there is research to help uncover the most effective treatments, doctors treat most cryptogenic stroke patients with aspirin — the kind you find in the average person’s medicine cabinet.  Recent research has suggested that stronger blood thinners also may be effective, and this is now being studied in major clinical trials.

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It’s still important to know the signs of stroke so you can get medical attention immediately. You won’t know if you’re having a cryptogenic stroke while you’re having it. And seconds matter for the initial treatment of all types of stroke, even if the cause is, ultimately, unknown.

If you think you or someone you know is having a stroke, call 911 right away. Then a doctor can decide what kind of stroke it is and how best to treat it.

What steps can help solve this diagnostic mystery?

One way doctors reduce the number cryptogenic strokes is to rule out everything else, Dr. Katzan says. “The level of medical evaluation after a stroke is critical and the diagnosis of cryptogenic stroke may depend on how intense the effort is to get the reason for the stroke,” she says.

Doctors typically do the following to find the cause of stroke:

  1. Evaluate the heart
  2. Monitor the heart rhythm
  3. Check the blood vessels in the head and neck
  4. Look at the brain tissue through brain imaging

Dr. Katzan suggests making sure your doctor takes these four steps. Seek a second opinion if you’re not confident doctors have done everything they can to find out what caused your stroke.

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What is the role of atrial fibrillation in causing strokes?

Atrial fibrillation (AF), a common type of irregular heartbeat, could cause some cryptogenic strokes, Dr. Saliba says. However, a stroke diagnosis is difficult if the AF happens intermittently instead of all the time. In other words, it may not occur while doctors are evaluating you.

For him, the key to classifying fewer strokes as cryptogenic may lie with better, or more continuous monitoring (21 days or more) for AF after a stroke. It’s not always possible to monitor someone full-time in a hospital until their heartbeat is irregular. However, Dr. Saliba sees potential in wearable devices to allow for longer, less intrusive monitoring.

How can you cut your risk of stroke?

With stroke, the best medicine is prevention. There are steps you can take to help prevent strokes. Dr. Saliba may focus on the heart while Dr. Katzan focuses on the brain, but both agree that lifestyle choices have the biggest impact.

Dr. Saliba says to prevent strokes, it’s important to reduce your risk. Your best bet is to make healthy food choices, keep your weight down and exercise to avoid high cholesterol and high blood pressure, both of which increase your risk of stroke.

If you have either high cholesterol or high blood pressure, the emphasis, says Dr. Saliba, is on controlling the problem. In addition to making healthy choices, it’s important to follow your doctor’s treatment plan, he says.

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