Silent Stroke: Diagnosis & Treatment

Instructor: Danielle Haak

Danielle has a PhD in Natural Resource Sciences and a MSc in Biological Sciences

A silent stroke is caused by brain arteries becoming blocked or damaged, thereby disrupting blood flow to the brain and causing cell death. They differ from other strokes because they don't present any symptoms! Let's take a look at how silent strokes are diagnosed and treated.

What is a Silent Stroke?

Jennifer was shocked when she got the news her grandmother had experienced a stroke. She was only 72 and had never had any major health issues other than having been diagnosed with an irregular heartbeat; specifically, her grandmother had experienced atrial fibrillation, a condition where the heart beats too quickly and causes the upper two chambers of the heart (the atria) to contract quickly and irregularly (called fibrillation). What surprised Jennifer even more was that her grandmother hadn't had any symptoms. She had had what's called a silent stroke and the damage wasn't detected until she had a brain scan as part of a routine check-up. Thinking back over the last few months, Jennifer realized her grandma's change in memory wasn't just attributed to 'old age.' There was an underlying cause!

Let's look at what silent strokes are and specifically how they are diagnosed and treated. A stroke occurs when arteries in the brain become blocked or damaged to the point that oxygen-rich blood can't be successfully delivered to cells in the brain. Without oxygen, these cells begin to die, resulting in damage to the affected parts of the brain. Most strokes cause symptoms like pain, numbness or weakness in parts of the body, confusion, or impaired vision, speech, or motor skills.

Silent strokes are usually ischemic strokes caused by blood clots.
ischemic strokes are often silent

Silent strokes are different because they may not cause any symptoms. Or, the symptoms may be unusual or subtle, misleading a person into believing there's nothing wrong or their symptoms are caused by something else. However, even without symptoms, a silent stroke is capable of causing permanent brain damage around the site where the stroke occurred. Many people don't even become aware of having experienced a stroke until they have a brain scan that shows damage. The memory loss Jennifer's grandma experienced was a symptom of the silent stroke but was mistaken for general memory loss due to age.

Her grandmother's condition is relatively common, and it's estimated that about one-third of people over the age of 70 have experienced at least one silent stroke! In fact, silent strokes are more common than strokes that cause symptoms to appear.

Jennifer's grandmother was unknowingly at risk of stroke due to her atrial fibrillation (irregular heartbeat), but another common risk factor is high blood pressure, or hypertension. An irregular heartbeat doubles the likelihood that someone will experience a silent stroke.

Diagnosing Silent Strokes

Without symptoms displaying, it can be difficult to diagnose a silent stroke. Victims may not be diagnosed until months after the fact, during a routine brain scan. Common scans include a CT (X-ray computed tomography) or a MRI (magnetic resonance imaging).

Immediately after a stroke, brain damage will appear on a CT or MRI scan. This damage shows up as dark spots on an image and may indicate areas of dead brain cells or areas where bleeding has occurred. This is important because it allows a doctor to identify which type of stroke the patient has experienced, which affects the type of treatment they need.

The most common type of stroke is an ischemic stroke, caused by a blood clot that blocks an artery, limiting or entirely blocking blood flow. Silent strokes are usually ischemic strokes. The other main type of stroke is a hemorrhagic stroke caused by a leaking or ruptured artery that causes bleeding in the brain.

If a person experiences an ischemic stroke, they will probably undergo a series of tests. These can include an electrocardiogram (ECG or EKG) to look for heart abnormalities or blood tests to check for any underlying conditions that may cause symptoms similar to a stroke.

Treating Silent Strokes

Once the type of stroke, area of the brain affected, and extent of damage are known, treatment options can be chosen. Treatment may include:

  • Thrombolysis, a process used to dissolve blood clots and restore blood flow through the use of medication.
  • Use of medication to treat an underlying condition like high blood pressure (a risk factor for silent strokes)
  • Surgery may be necessary to fix damaged arteries, relieve pressure to due bleeding, or remove a blood clot that doesn't respond to medication

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