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Doctor points out signs of stroke in COVID-19 patient’s MRI brain scan.

Connections Between COVID-19 and Stroke You Need to Know

Apr 09, 2021

The connections between COVID-19 and stroke may boil down to a combination of factors, including complications that come with an infection or pre-existing conditions. Here are answers to some frequently asked questions about COVID-19 and its connection to stroke.

Can COVID-19 increase your risk of stroke?

COVID-19 may increase the risk of stroke. Studies show that up to 4.9% of COVID-19 patients suffer an acute ischemic stroke during their first hospitalization. This increased risk of stroke is due to a number of factors brought about by COVID-19, such as increased blood clotting, as well as diabetes and high blood pressure.

What is an ischemic stroke? This is a common type of stroke that occurs when a blood clot blocks the blood supply to the brain.

Some lifestyle factors also set the stage for the risk of stroke. These include smoking, poor diet, and high cholesterol levels. These long-term risk factors leave blood vessels vulnerable to a sudden trigger event, like a viral infection.

Can COVID-19 cause a sudden stroke?

Doctors and researchers alike who have been working on COVID-19 patients have noted that severe cases of the disease involve the rapid formation of blood clots. This increases the risk for stroke, as well as heart attacks and heart failure.


“As the surgical critical care team at Baylor St. Luke's Medical Center was discussing their work in the ICU a few weeks ago, I was amazed to hear them express that one of their greatest challenges was that the central intravenous and arterial lines and the dialysis catheters kept unexpectedly clotting in COVID-19 patients in the ICU.”

- Dr. Todd Rosengart
  Department of Surgery Chair of the Department of Surgery at Baylor College of Medicine
  Cardiothoracic Surgeon at Baylor St. Luke’s


In a study conducted at Baylor St. Luke’s Medical Center by Baylor College of Medicine, researchers found that more than half of admitted COVID-19 patients developed significant blood clots. A majority of these cases evaded routine blood clot screenings. 

Can COVID-19 cause strokes in younger adults?

While rare, it is a possibility. In a report published in April 2020, five cases of large-vessel stroke were recorded in COVID-19 patients who were all below the age of 50. All patients were previously healthy, had no pre-existing conditions, but had presented new-onset symptoms of large-vessel ischemic strokes. 

Why do strokes occur in younger adults with COVID-19?

The occurrence of strokes in younger adults is one of the more mystifying twists brought about by COVID-19. A common theory is that younger and healthier patients can easily bypass and recover from the respiratory issues brought about by the virus but develop more serious issues later on. Infected patients have been known to experience the deadliest type of stroke, where large clots block blood flow, damaging parts of the brain. These include areas that are responsible for speech, decision-making, and movement.

Does COVID-19 cause abnormal blood clotting?

The occurrence of strokes in COVID-19 patients may be the result of unusual clotting problems indirectly brought about by the virus. A study done in November 2020 found parallels between COVID-19 and antiphospholipid syndrome (APS), an autoimmune condition that causes similar blood-clotting abnormalities. In both cases, a patient’s immune system releases autoantibodies that promote the rapid formation of multiple blood clots in large arteries, veins, and even the most microscopic of capillaries.

Does COVID-19 cause brain damage?

COVID-19’s most common symptoms are the loss of smell and taste, headaches, fatigue, and brain fog. This has led researchers to believe that the disease may also cause neurological problems. Post-mortem studies on human brain tissue samples reveal that these neurological symptoms are likely caused by the body’s inflammatory response to the SARS-CoV-2 virus.

MRI imaging showed signs of inflammation and bleeding in the olfactory bulb and brain stem. These are areas of the brain that control the ability to smell and regulate heart rate and breathing. Small blood vessels in these areas were shown to be abnormally thin. Many leaked out blood proteins that caused an aggressive immune reaction.

Genetic material from the virus itself was absent in the brain tissue samples. However, other studies of mouse and human brain tissue have suggested a direct influence of the virus on the central nervous system with signs of viral neurons found in the cerebral cortex.

What are the signs of a stroke?

A stroke can occur in anyone at any age. Here are some ways you can recognize a stroke: 

  • Facial Drooping - Part of the face becomes lopsided or droopy.
  • Arm Weakness - Weakness and numbness in one arm.
  • Speech Difficulty - Slurring speech or inability to speak simple sentences.
  • Time - Time is of the essence, so call 911 and note the time the symptoms appeared.

If you suspect a stroke, call 911. You may request the ambulance take you to one of our DNV-Certified Comprehensive Stroke Centers or an affiliated St. Luke’s Health emergency room for high-quality treatment.

COVID-19 increases your risk of stroke, as well as a host of other health complications. Learn more about scheduling a vaccination appointment at St. Luke’s Health.


Journal of NeuroInterventional Surgery | Ischemic Stroke in COVID-19-Positive Patients: An Overview of Sars-Cov-2 and Thrombotic Mechanisms for the Neurointerventionalist 

American Heart Association News | Flu and COVID-19 Are Bad Enough, but They Also Can Raise Stroke Risk

Baylor College of Medicine | Tests Can Identify Undetected Blood Clots in COVID-19 ICU Patients

The New England Journal of Medicine | Large-Vessel Stroke as a Presenting Feature of COVID-19 in the Young

The Washington Post | Young and Middle-Aged People, Barely Sick With COVID-19, Are Dying of Strokes

Science Translational Medicine | Prothrombotic Autoantibodies in Serum From Patients Hospitalized With COVID-19

NIH Director’s Blog | Taking a Closer Look at COVID-19’s Effects on the Brain
The New England Journal of Medicine | Microvascular Injury in the Brains of Patients With COVID-19

Journal of Experimental Medicine | Neuroinvasion of SARS-CoV-2 in Human and Mouse Brains