Thomas Meinel, MD
A lot of brain MRI scans are performed every day, for example because of headache, seizure, or trauma. Those scans occasionally reveal chronic scars of previous brain tissue damage, but in patients who are unaware of any prior stroke symptoms. In medical terms, those scars represent an incidental finding, meaning the scar tissue does not have association with the indication for the planned MRI.
The frequency of covert infarction increases with age, and roughly 30% of 70-year-old individuals have covert infarctions. They can be found more frequently when cardiovascular risk factors such as arterial hypertension, diabetes, or smoking are present. It is estimated that brain infarction occurs three to five times more often without causing symptoms than with typical symptoms of stroke. How can this be explained?
We know that some areas of the brain carry a very specific function, and if a stroke occurs there, it will trigger symptoms such as weakness or speech problems. However, big parts of the brain have no “direct function,” or more subtle function like voice modulation or short-term memory and these interruptions to function may go unnoticed. Imagine your car, if a technical defect occurs in the engine, it may break down and you immediately notice it, whereas if your rear lights fail, you won’t necessarily notice until your whole car is checked.
Previously, those covert infarctions have been called “silent strokes,” but due to the increased risk for stroke, death and dementia, the term “silent” is misleading. Additionally, covert infarctions are associated with visual field defects, coordination problems, mobility issues, frailty, and depression — subtle problems that might only be picked up in a careful examination and hence are called covert deficits or “whispering” symptoms of stroke. In the example with the car with the failing rear lights, you are at increased risk for serious potential consequences.
For stroke prevention, thorough guidelines exist on which diagnostic tests to run to identify the cause of the stroke and to find the best medication for prevention of another stroke. Doctors tailor prevention with the assistance of expert opinions and statements from the American Heart Association/American Stroke Association and European Stroke Organisation on this topic and take into account, one’s risk factors when discussing medications and treatment options.
Given the serious consequences, it is important that the treating physician addresses the covert brain infarctions or “silent strokes” and acts upon them to assess and treat modifiable cardiovascular risk factors. It is even more important that patients themselves see covert brain infarctions as a warning and change their lifestyle by maintaining a healthy body weight, incorporate exercise, and avoid smoking and excess alcohol, as well as eating a healthy, balanced diet.
In this way, covert brain infarctions are an opportunity for the prevention of vascular disease and brain health before patients experience symptoms.
Questions you can ask your doctor after a brain scan:
- Did my scan show signs of vascular damage?
- Does the scar look like it might have originated from the heart? What may have caused it?
- How often should I take my blood pressure?
- Should we check my lipid/cholesterol levels or test for diabetes?
- Should I screen for an irregular pulse? What are the potential ways to check for this condition?
- Which risk factors should I work on preferentially?
- Can you assist me to quit smoking?
- What else can I do to reduce my risk of stroke and improve my brain health?