Silent strokes occur when a clot blocks a blood vessel in the brain, but the person experiences no noticeable symptoms. This can cause damage to a small part of the brain.

Due to a lack of noticeable symptoms, silent can be difficult to identify. However, people may have slight mobility or memory issues.

Doctors usually find silent strokes when a person has a brain scan for another condition. For example, the doctor may notice a past silent stroke if a person has a scan for continual headaches or dizziness.

Read on to learn what silent strokes are, how to recognize them, causes, treatment options, and more.

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A silent stroke is a stroke without any noticeable symptoms.

Usually, a stroke occurs due to a blocked blood vessel in a person’s brain. This can damage a part of the brain that controls essential functions, such as controlling the muscles of one arm.

In turn, this can lead to symptoms such as weakness or paralysis.

However, if the stroke only damages a small part of the brain that does not control essential functions, a person may experience no symptoms. This is why healthcare professionals describe a stroke of this kind as “silent.”

Silent strokes do not present with any obvious symptoms or signs. However, a person might have slight memory or mobility issues that they have not considered could be connected to a stroke.

Instead, silent strokes tend to reveal themselves on brain scans for other conditions, such as headaches, cognitive issues, or dizziness.

A doctor may diagnose a silent stroke when they find the following signs on a person’s brain scan:

  • white spots
  • scarred tissue
  • tiny areas of bleeding vessels

Signs of a silent stroke may be very subtle. They are mistaken for regular signs of aging, such as:

  • difficulty balancing
  • falls
  • difficulty with bladder control
  • mood changes
  • reduced ability to think

A silent stroke is similar to an ischemic stroke as it results from a clot blocking a blood vessel in the brain.

Although a transient ischemic attack also blocks a blood vessel with a clot, it is only a temporary blockage. This is different from a hemorrhagic stroke, which results from a damaged artery leaking blood into the brain and causing a pressure buildup.

Atrial fibrillation, which commonly causes irregular heartbeat in people over 65 years, is linked to silent strokes. The condition more than doubles a person’s risk of having this type of stroke.

These two conditions also share the same risk factors, including high blood pressure and elevated blood levels of homocysteine.

As silent strokes often go undetected, a person may never know they need treatment.

Alternatively, they may only discover they require treatment following screening for another health condition. If a person has a brain scan and their doctor detects one or multiple silent strokes, they may prescribe medications.

For instance, blood thinning medications can help to lower blood pressure, and cholesterol medications can help to lower low-density lipoprotein (LDL) cholesterol. This can reduce their risk of future strokes.

A silent stroke is a risk factor for a future stroke. It can also be a sign that a person has progressive brain damage.

A person with multiple silent strokes may be at higher risk for mild cognitive impairment and early dementia.

An estimated 8–11 million people in the United States experience silent strokes each year. This compares with 800,000 who have a stroke with the classic symptoms each year.

According to a 2016 scientific statement, the risk of stroke increases with age. It reported that 25% of people over 80 years experience at least one silent stroke.

The Centers for Disease Control and Prevention (CDC) provide advice to help people avoid having strokes. This guidance includes making healthy choices and managing pre-existing health conditions, such as:

The American Stroke Association provides similar guidelines for stroke prevention. These also include diet and lifestyle changes, such as:

  • eating a Mediterranean diet — an eating pattern that includes nutritious whole foods, such as whole grains, fruits, vegetables, seafood, beans, and nuts
  • reducing sodium intake

A person should consult a doctor if they experience any difficulty with balance, headaches, dizziness, or clumsiness in a limb that lasts a few days before resolving.

As people are more likely to experience strokes as they get older, they may find it difficult to notice or remember any mild symptoms. A person with a friend or family member at risk for silent stroke should look for any mild stroke symptoms in their loved one.

Silent strokes have no noticeable symptoms, but they may still injure a person’s brain. A silent stroke is also a risk factor for a future stroke.

A doctor may detect a person has had a silent stroke while screening for another condition and may prescribe blood thinners or cholesterol-lowering medication.

People may mistake stroke symptoms as signs of old age, so it is important for individuals to discuss any temporary increased clumsiness with a doctor, as this could be a sign of a silent stroke.