What’s the connection between COVID-19 and stroke?
That was the question during an early session of the International Stroke Conference on March 19.
While the past year has yielded useful data, the primary consensus among a group of scientists who looked at the topic is that more study is needed.
Brett Cucchiara, MD, professor of neurology at the University of Pennsylvania, noted that in the early days of COVID-19, news of the virus causing sudden stroke in young adults created alarm in the public and among neurologists. As data has emerged, Cucchiara said, findings indicate that stroke among young adults is a relatively infrequent complication of CVOID-19.
Cucchiara also noted a somewhat startling drop in stroke incidence in the first few months of the pandemic.
“The conventional wisdom was that it was likely that patients with stroke were avoiding the hospitals due to fear of COVID,” he said. “But the sheer drop-off makes that improbable. Would such a number of disabling strokes stay at home?”
In a study of more than 1 million inpatient visits, looking at a rate of hospital admission in 2020 and 2019, there was a drop in stroke admissions of 25 percent, and an even larger drop in admissions for myocardial infarctions (MI).
“Surprisingly, the drop in stroke and MI was 16 to 17% throughout the summer, while other conditions went back to the baseline,” he said.
Cucchiara suggested that some of the things done as part of the lockdown and stay-at-home orders might have contributed to reduced stroke incidents. Among them:
- Air pollution reduction. Air pollution causes spokes in cardiovascular diseases, and worldwide, there has been a reduction in some air pollutants.
- Dietary changes
- Risk factors are more controlled
- Improved medication compliance
Cucchiara noted the thought that really sick people aren’t coming to the hospital, but said that there hadn’t been a corresponding increase in mortality.
“If we want to be optimistic, reduced rates of stroke could be a silver lining of the pandemic,” he said, while warning, “there is still much to learn about stroke prevention.”
Marion Buckwalter, MD, PhD, of Stanford Stroke Center, and professor of neurology and neurological sciences at Stanford, took a close look at dementia post-stroke and whether COVID could exacerbate that.
She outlined the many effects of stroke – motor/functional impairment, depression, fatigue, seizures -but noted that dementia can be the most debilitating. She noted that the risk of dementia doubles after a stroke.
“In addition to damaging tissue acutely, we believe that stroke triggers a response that causes neurological diminishment and dementia,” Buckwalter said.
Without enough data about COVID yet, Buckwalter discussed the effects of sepsis, another infection, to project what effects COVID might have on patients.
“After severe sepsis,” Buckwalter said, “the odds increase to develop dementia and increase functional impairment. It’s highly likely that sepsis and COVID cause an inflammation of the auto immune system that can lead to stroke. The jury is still out on the damage that COVID and sepsis can cause in the brain, and there aren’t a lot of large studies yet.”
Buckwalter pointed out that depression and mood anxiety increase with COVID-19 and hospitalization.
“We need more studies about the long-term cognitive outcomes after COVID-19, and we need to understand the interactions between stroke, CVOID and those long-term cognitive outcomes,” she said.
Hooman Kamel, MD, MS, Chief, Neurocritical Care, and Vice Chair, Research at the Department of Neurology at Weill Cornell Medicine, discussed whether COVID leads to an increased risk of large vessel occlusion in young patients.
“A lot of the research about COVID shows an emerging story that there’s a large vascular component,” Kamel said. “We know that COVID causes systemic endotheliopathy (affliction of protective cells in the body), and compared to critically ill patients without COVID, COVID-19 patients have higher levels of higher coagulation (blood turning to a semi-solid or solid state).”
Kamel noted that CVOID patients not infrequently had arrythmias, atrial fibrillation and other forms of myocardial injury that could all lead to stroke.
He cited a Mt. Sinai study that looked at the concern that COVID might be leading to a higher risk of stroke in young patients. He also noted that the strokes in COVID patients happened well into hospitalization, and was happening among sicker patients, who were treated with ventilation and were in prone positions. He also noted that COVID-related strokes are more severe than in non-stroke patients. The study also showed more large vessel occlusion in COVID patients.
“COVID causes a robust clotting phenomenon,” he said. He concluded from studies:
- CVOID -19 increases the risk of large vessel occlusion
- COVID is more strongly associated with stroke than other viral infections
- CVOID-associated strokes occur late in the disease among sicker patients, and are more severe than typical stroke
- Anticoagulation prevents critical illness in CVOID 19
Kori Zacherson, M.D. MSc, associate professor of emergency medicine at Massachusetts General Hospital and Harvard Medical School, used the Bradford Hill criteria, developed by British epidemiologist Sir Austin Bradford Hill for determining a causal association, to assess whether COVID really does cause increased large vessel occlusion.
Her analysis was that more study of COVID is needed before that can be decidedly concluded.