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Does COVID-19 Cause Strokes?


It was bad enough that an exceptionally dangerous new respiratory virus was ravaging New York City in March and April 2020. Then doctors noticed something else. “Early in the COVID-19 pandemic, we started seeing alarming reports of young patients without typical risk factors who developed severe stroke,” says vascular neurologist Kathryn Cheponis, MD, with Lehigh Valley Hospital (LVH) Neurology–1250 Cedar Crest.

In the space of two weeks, five New Yorkers between ages 33 and 49 had blockages in arteries of the brain – more than five times the expected number in such a normally low-risk population during such a short period of time, Cheponis recalls. “This was a disturbing increase and looked like an anomaly,” she says. “But all five were diagnosed with COVID. That was the first signal this might be an area of concern.”

A blockage in an artery of the brain is the hallmark of ischemic stroke, the most common form. It occurs when a blood clot either develops elsewhere in the body such as the heart and travels to lodge in the brain or forms at the site of the blockage. In either case, impaired blood flow can deprive the brain of oxygen and damage brain tissue or even lead to death. Could COVID-19 be related to stroke?

“In those early days, a lot of information about COVID-19 was coming in without a lot of context,” Cheponis says. “We didn’t know what it meant yet.”

Subtle connection

As the pandemic enters its second year, potential links between COVID and stroke are better defined, but the relationship is complex and nuanced. “Changes in clotting systems through the whole body have become clearer, especially in people with severe COVID,” Cheponis says. “We especially see clotting in microscopic tissues of the lungs.”

It’s thought that inflammation from the virus may trigger tiny lung clots. “One theory is that inflammation in cells lining artery walls likewise makes people with COVID prone to large, disabling strokes,” Cheponis says. “But no one has been able to prove that association.”

In fact, tiny lung clots may use up platelets in blood that help blood coagulate, preventing them from contributing to larger clots. “Looking at the big picture, there may not be a greater stroke risk in COVID patients,” Cheponis says, “or some may be at higher risk, but not all.”

Instead, a more subtle – and, fortunately, avoidable – link has emerged. As the pandemic gained momentum, stroke cases in hospitals actually dropped, but not because fewer strokes were happening. “People with milder stroke symptoms were staying home” due to concerns about catching the coronavirus, Cheponis says. “Since the pandemic’s one-year mark, we’re seeing people with manageable conditions that have been neglected who are now experiencing serious consequences of delayed care.”

Early treatment is important

In the first 24 hours of a stroke, an array of treatments can minimize its effects. “We can administer intravenous clot medications that increase the likelihood of a complete recovery,” Cheponis says. “For a major blockage, we can go in with a catheter through a blood vessel to remove a clot. But if you come in two weeks later, there’s not a lot we can do to reverse the damage.”

Many people also delayed or neglected care for conditions that predispose them to stroke such as atrial fibrillation (irregular heartbeat) or heart valve surgery. “We’ve seen many people, for example, who’ve had trouble managing blood thinners during the pandemic and experienced significant repercussions,” Cheponis says.

Others have had trouble controlling blood pressure or diabetes. Often, people have reduced their activity. “All of these can affect traditional vascular risk factors that increase the likelihood of stroke,” Cheponis says.

Reducing risks

As the pandemic continues, COVID-19’s association with stroke appears largely manageable. “Most important is prioritizing normal, routine medical care,” Cheponis says. “Telehealth and video visits are very safe and make it possible to monitor risk factors such as blood pressure, cholesterol and blood sugar.”

It’s also important to recognize signs of a stroke. “If you notice weakness or numbness on one side of the body, a drooping face, trouble speaking or understanding speech, loss of vision or sudden severe dizziness that doesn’t go away, you should call 911,” Cheponis says.

Stroke Warning Signs

Learn the symptoms of a stroke

Do not ignore any of these warning signs, even if you experience just one of them. Take action immediately, even if symptoms go away. Stroke is a time-sensitive brain emergency. Call 911 immediately.

Learn the symptoms

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