What is a silent stroke?

A silent stroke is a stroke that doesn’t produce symptoms.

A silent stroke is a stroke with no or mild symptoms. Very frequently when you do a brain scan, especially on older people, you see evidence of prior strokes on that scan. The issue is, what does silent mean in the context of an old and undiagnosed stroke? Is it that the patient felt something but brushed it off, or was it truly silent with no symptoms at all? In reality, for a lot of so-called silent strokes, we usually think the stroke had minor symptoms and the patient brushed it off. Occasionally a stroke doesn’t cause symptoms at all, however.

A stroke often becomes apparent when a person suddenly develops slurred speech or loses sensation or the ability to move on one side of the body, either partially or completely. However, strokes can affect parts of the brain that control other parts of the mind/body's functioning, such that the changes are not so obvious. Such strokes are sometimes called "silent." These strokes may affect one's mood or ability to think or communicate clearly, and may go unnoticed. It is very common for elderly people who have an MRI of the brain for other reasons to show evidence of having had a stroke that they were completely unaware of. This means that strokes are far more common than many of us realize, and this should make us place even more value on stroke prevention.

Dr. Jeffrey L. Saver, MD

In silent strokes, brain injury occurs from blockage or rupture of a blood vessel, but does not cause major, immediate symptoms, such as sudden weakness on one side of the body or sudden trouble speaking. The absence of typical immediate stroke symptoms is because the amount of brain injury is small and located in a less critical brain region. However, although a single small stroke may be “silent,” multiple such strokes can add up to cause substantial brain injury and contribute to problems in thinking (dementia), walking difficulty, and other chronic brain symptoms.

Dr. Michael Breus, PhD
Psychology Specialist

Silent strokes have the following characteristics:

  • Silent strokes have no visible or outwardly identifiable symptoms.
  • In most cases, people who suffer a silent stroke don't even know they've had a stroke.
  • Silent strokes are referred to as "silent" because they do not present the outward physical symptoms that are typically associated with stroke, including slurred speech, paralysis, and severe pain.
  • Silent strokes are a serious health concern, however—they cause permanent damage to the brain, most often in the regions of the brain that govern mood, thought, cognition and memory.
  • Silent strokes are themselves a risk factor for other types of stroke, including major stroke.

A silent stroke is a stroke that occurs in a part of the brain where there are no immediately apparent symptoms. Different parts of the brain control different functions, and the symptoms of a stroke depend on the part of the brain that is damaged by the stroke. For example, a stroke involving the left frontal lobe would cause language problems because this part of the brain specializes in expression of language. Some parts of the brain are relatively “silent,” or strokes in these parts cause subtle problems that may not be picked up immediately. A buildup of “silent” strokes over time has an effect on cognition and function, so no stroke is exactly “silent.”

Dr. Audrey K. Chun, MD
Geriatric Medicine Specialist

Silent strokes are small vascular events in the brain—such as a brief interruption of blood flow to an area of brain tissue—that cause lasting damage. However, unlike a stroke that is accompanied by symptoms such as acute weakness, numbness or language difficulties, you may never know you had a silent stroke until you get a brain magnetic resonance imaging (MRI) scan, which will show areas affected by the cerebrovascular event.

Silent strokes may cause subtle changes in cognitive function and can have a profound impact on your future health. Silent strokes have been associated with dementia, impaired mobility and falls, and they raise the risk for a full stroke.

It is possible to have a stroke and not know it. This is referred to as a silent stroke. An MRI taken for some unrelated purpose may show lesions on your brain. Those lesions are evidence of damage to the brain tissue caused by a stroke. At that point, you cannot repair the damage, but it is important to know that you are at greater risk for stroke then you may have realized. Talk with your doctor about what you can do to reduce your risk of having another stroke in the future.

Dr. Steven A. Meyers, MD
Diagnostic Radiologist
A silent stroke is a stroke that does not produce any symptoms. Sometimes a person with have a brain scan which shows an old stroke but the person never had any symptoms. This may indicate that the person is at risk for future vascular events such as stroke or heart attack.

A silent stroke occurs in the parts of the brain that do not control speech, motor functions or the senses.

Since silent strokes do not have any of the regular signs, they are often discovered incidentally. For example, you might have a severe headache, and the doctor will take some images of your brain using a CT scan or MRI. If you’ve had a silent stroke, these images may show evidence of a brain insult or scar tissue. The doctor will probably ask you if you’ve had any stroke symptoms such as weakness, numbness, tingling, inability to speak, inability to see and if the symptoms were transient, but you may not remember having any of the symptoms.  

Luckily, the quality of imaging we have these days shows tiny things that we couldn’t see 10 years ago. 

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.