If you have never had the outward symptoms of a massive stroke and think you are in the clear, think again. Researchers are finding that more than 11 million Americans suffer from a silent stroke every year. This is far more than the 750,000 people who have traditional, symptomatic acute strokes. If you have high blood pressure, high cholesterol, or out of control diabetes, you are at risk for these quiet, symptom-free brain strokes. Chances are you won’t even know you had one, and they can cause medical issues that may be attributed to other conditions. Learning about silent strokes – and how to avoid them – is important for all stroke patients over 50, especially if you have risk factors.
Defining a Silent Stroke
A silent stroke means that you do not experience the traditional symptoms of a massive stroke, such as one-sided paralysis, difficulty speaking, or headache after a stroke. Silent strokes can happen in the same way that regular acute strokes occur. For instance, either a clot stroke or a bleed stroke can lead to this smaller form of stroke. The only way you will ever know if you had a silent stroke is if you have a CT scan or an MRI of the brain. These tests will show a small area of dead brain tissue, usually in an area that does not typically cause traditional acute stroke symptoms. If you have a silent stroke, it makes you even more susceptible to a transient ischemic attack (TIA) or a massive stroke.
Many different risk factors can lead to a silent stroke. The most common ones are high blood pressure that is uncontrolled by medication and high cholesterol. Both of these can lead to clots strokes and bleed strokes in the brain that are too small to cause normal symptoms of a massive stroke. Atrial fibrillation is another leading cause of stroke. This is the abnormal beating of one part of your heart that can cause clots. Diabetes mellitus is another common risk factor for silent strokes. Metabolic syndrome, a precursor for diabetes, chronic inflammation as indicated by c-reactive protein levels, and cigarette smoking round out the risk factors from which you need to protect yourself.
Silent Stroke and Memory
You might think that having a silent stroke does not affect your life and is not something you should concern yourself with. In fact, silent strokes can cause memory loss, and this sign is often wrongly interpreted as Alzheimer’s disease. You can have more than one silent stroke, and the sum consequence of the many minor damages can lead to an overall decline in cognitive ability. It happens slower than a regular acute stroke, so your doctor may not even be aware that a silent stroke is causing your memory and cognitive problems.
A study published in 2011 in the Journal of Neurology studied 658 people with an average age of 79 and no history or dementia. They found that 174 people had silent strokes, and these stroke patients did not perform as well as non-stroke patients in cognitive and memory function tests. If you are having mental decline, it might be worth it to ask for an MRI and also to control your risk factors.
Silent Stroke and Sleep Apnea
New research is showing that one of the more deadly side effects of sleep apnea is the tendency to cause silent strokes. Sleep apnea is a common condition in which you stop breathing during your sleep. It is often caused by excess tissue hanging down the back of the throat and closing off the breathing passageway. Most people who have sleep apnea snore quite loudly or actually gasp in their sleep. This causes less oxygen to the brain, and sleep apnea has already been implicated in causing high blood pressure and heart failure. The treatment for sleep apnea is a mask that blows a constant stream of air into your nose and mouth to keep the passage open. It is often an uncomfortable treatment, and many patients are unable to tolerate the mask. However, untreated sleep apnea can cause serious medical problems.
A study presented at the American Stroke Association’s International Stroke Conference studied stroke patients who have had strokes or TIAs to see if there was any connection between sleep apnea and acute strokes. The study found that 91 percent of those who had previous strokes stopped breathing in their sleep. Since silent strokes and acute strokes occur from the same mechanism of action in the brain, this means that those with sleep apnea are at high risk of silent strokes, as well. Research is still underway to determine if the lack of oxygen somehow upsets the vasculature in the brain to cause an acute stroke or silent stroke. The message is clear, though: if you snore or have diagnosed sleep apnea, you need to seek treatment for it to avoid this costly side effect.
Wikipedia; Silent Stroke
ABC News; Study: Million Suffer Silent Strokes; Daniel Q. Hanley
ABC News; Silent Strokes Linked to Memory Loss in Older Adults; Lara Salahi; December 2011
Huffington Post; Sleep Apnea, Silent Strokes Linked: Study; February 2012