Strokes: A Silent Crisis
Silent strokes: What’s the Real Issue?
Sickle Cell Disease causes a myriad of symptoms. From pain crises to organ damage, the effects of this disease are debilitating, and when untreated, they can be potentially deadly. Perhaps one of the most troubling effects is the prevalence of what are known as silent strokes. There are many proposed causes of these incidents, such as the brain not receiving enough oxygen, however, there is not yet any definitive answer as to why these events happen.
One of the reasons that silent strokes are so damaging is that they happen primarily in children diagnosed with Sickle Cell Disease. Secondary to this, silent strokes are, as suggested by the name, silent. There are no warning signs such as those associated with typical strokes. Children who suffer from these events show little to no symptoms: no difficulty speaking, no muscle weakness, no temporary paralysis.
The only way to determine if a person has suffered a silent stroke is through brain imaging, such as an MRI.
There are some discrepancies on how many people actually experience silent strokes, however it can be determined that at least 17% of children under 14 who have SCD will experience at least one silent stroke, while children under 18 have a higher risk of 23%. These numbers are actually low compared to others, with some estimating that up to 37% of children with SCD will suffer a silent stroke by the age of 14. In addition, once a child has experienced one silent stroke, there is roughly 67% chance that they will experience another one within the following year. Regardless of the “correct” number, any percentage should be considered too high, as these events can have life-long, detrimental aftereffects.
Some studies suggest that silent strokes in children lead to break down of brain matter that is similar to that which occurs in elderly dementia patients. In fact, there are many visible similarities between brain images of children after a silent stroke, and an elderly patient with dementia. Strokes can occur in two different types of brain tissue: grey matter and white matter. Grey matter is the part of the brain that has neurons, the cells that store information. Strokes in grey matter almost always lead to partial paralysis, loss of motor function, and other very noticeable symptoms.
In fact, there are many visible similarities between brain images of children after a silent stroke, and an elderly patient with dementia.
However, white matter is very different. The white matter parts of your brain contain the “highways” that your neurons use to send signals. Silent strokes typically affect this part of your brain. While they don’t result in visible symptoms, they impact the ability of your neurons to send signals, causing your memory and thought processing to slow down.
A recent study explained that the human body is capable of adjusting parts of its physiology to respond to problems within the body. This is very evident in silent strokes. This study found that the total amount of oxygen being sent to the brain is not usually decreased by very much in Sickle Cell Disease patients. However, the body compensates for low oxygen levels elsewhere by prioritizing blood flow to the grey matter areas. This is because grey matter health is essential for life and bodily function; when the grey matter is affected, the whole body is affected. However, this prioritizing causes the white matter areas to receive less oxygen, which leads to silent strokes.
It is imperative to discuss any concerns with your doctor, if you need any assistance we are here to help.
Disclaimer: All information contained in the Sickle Cell 360 blog is intended for general, eduational or background purposes only and should not be used as medical advice for any individual. Please consult your health-care provider or providers for information specific to your own condition or illness. If you need assistance locating a medical doctor or other health-care provider, please call us at 1-844-994-Hope or email us at info@sicklecelltx.org.
References:
Marano, M., Quattrocchi, C., Ombretta, A., Avvisati, G., & Di Lazzaro, V. (2014). Recurrent large volume silent strokes in sickle cell disease. Journal of Stroke and Cerebrovascular Diseases, 23(10), e453-e455.
DeBaun, M. R., Armstrong, F. D., McKinstry, R. C., Ware, R. E., Vichinsky, E., & Kirkham, F. J. (2012) Silent cerebral infarcts: a review on a prevalent and progressive cause of neurologic injury in sickle cell anemia. Blood, 119(20), 4587-4596.
Chai, Y., Bush, A. M., Coloigner, J., Nederveen, A. J., Tamrazi, B., Vu, C…. & Wood, J. C. (2019). White matter has impaired resting oxygen delivery in sickle cell patients. American Journal of Hematology, 94(4). doi: 10.1002/ajh.25423