What is a Silent Stroke?

You could have a stroke and not know it, and more than one-third of people over age 70 have had at least one silent stroke. Learn the silent stroke symptoms, how to diagnose, and prevention.

brain scan for silent stroke

A silent stroke happens so quickly, you will not know that you're having one. They go undetected until a CT scan or MRI shows them.

© Chinnapong | Getty Images

A regular stroke is a 911 emergency. It is an interruption of blood flow to part of your brain. Without blood, brain cells start to die. This stroke causes sudden symptoms like numbness and weakness on one side, loss of speech or the ability to understand speech, dizziness or loss of balance and double vision or loss of vision. If treatment is not started very quickly, this stroke may cause permanent damage. That’s why you always call 911.

Silent Stroke Symptoms | Risk Factors | Silent Stroke Treatment


A silent stroke does not cause the same symptoms as a typical, ischemic stroke. A silent stroke is usually discovered when your doctor orders a brain imaging study, like a CT or MRI scan for another problem. You might be getting one of these scans for a problem like headaches, dizziness, memory loss, or to rule out Parkinson’s disease. Silent stroke is diagnosed when a scan finds an unexpected spot in the brain caused by dead brain cells. Silent strokes are also caused by interrupted blood flow, but they only affect a small area of the brain that is not responsible for speech, movement, or vision.

A silent stroke is not the same as a ministroke. The proper name for a ministroke is a transient ischemic attack (TIA). A TIA causes the same sudden symptoms as a regular stroke, but symptoms don’t last as long, usually only a few minutes, so they don’t cause permanent damage. They go away on their own without treatment. However, a ministroke is an early warning sign for a regular stroke. One in three ministrokes will be followed by a regular stroke, usually within 48 hours.

Mild Stroke or Silent Stroke Symptoms?

Silent strokes do not cause any obvious symptoms. You might have mild stroke symptoms like feeling a little dizzy or clumsy for a while. You might feel a little confused or struggle with memory, but you might not have any symptoms at all. If you have several silent strokes over time, damage can start to accumulate. Memory problems, confusion, or clumsiness become more noticeable. Silent strokes may increase your risk for cognitive decline, dementia, and a regular stroke.

Are You at Risk for a Silent Stroke?

Like ministroke and regular stroke, silent strokes are almost always caused by a blocked blood vessel. Fatty deposits inside blood vessels, callers atherosclerosis, may form blood clots that obstruct blood flow. This can happen inside the brain. It can also happen in the heart, neck, or chest. In these cases, the clot breaks free and travels to the brain where it lodges in a small vessel and blocks blood flow, called an embolism. The most common cause of an embolism from the heart is atrial fibrillation (AF). AF is the most common heart rhythm disorder in older people and stroke is the most dangerous complication.

High blood pressure is another common risk factor for silent stroke and other strokes. If the upper blood pressure number, called the systolic blood pressure is elevated, so is your stroke risk. Risk factors for silent stroke (and other strokes) include:

    • High blood pressure
    • AF
    • Atherosclerosis
    • High cholesterol, especially the HDL (bad) cholesterol
    • Diabetes
    • Obesity
  • Smoking
  • Lack of exercise
  • A family history of stroke

The only way to diagnose a silent stroke is with a brain imaging study. The best study is an MRI. Doctors do not routinely do brain imaging on older people to rule out silent stroke. However, you should let your doctor know if you have symptoms like dizziness, clumsiness, memory loss, or confused thinking. If you have risk factors for stroke, an imaging study might be appropriate.

Silent Stoke Treatment and Prevention

If your doctor diagnoses a silent stroke, you should have treatment to prevent more silent strokes or a more severe stroke. This is called stroke prevention treatment and can reduce your risk of stroke by 80 percent or more. Stroke prevention may include treatment for AF, high cholesterol, or high blood pressure. It may also include using a blood thinner to prevent blood clots. Your doctor will decide on the best treatment based on your risk factors.

You can also make some important lifestyle changes to reduce your risk of stroke. These include:

  • Working with your doctor to control your blood pressure, cholesterol, and blood sugar
  • Limiting salt to about one teaspoon per day
  • Reaching and maintaining a healthy weight
  • Eating a heart-healthy diet
  • Not smoking
  • Getting at least 30 minutes of exercise on most days of the week

An important final tip is to remember this acronym: FAST. It stands for the sudden warning signs of stroke you should never ignore. F is for “face that droops.” A is for “arm that gets weak.” S is for “speech difficulty.” T is for “time to call 911.”

be fast stroke prevention for silent strokes

Knowing “BE FAST” can help you spot a stroke. Look for tell-tale signs of stroke like a loss of balance, blurred vision, and drooping on one side of face.

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Chris Iliades, MD

Dr. Chris Iliades is board-certified in Ear, Nose and Throat and Head and Neck Surgery from the American Board of Otolaryngology and Head and Neck Surgery. He holds a medical … Read More

View all posts by Chris Iliades, MD

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