Nearly 10 percent of COVID-19 patients who experienced cognitive symptoms and who were hospitalized during the early days of the pandemic experienced nonconvulsive seizures, scientists reported in The Annals of Neurology in March. And many more of these patients were found to have abnormalities in brain rhythms that don’t rise to the threshold of a seizure, but are still indicative of a decline in brain function.
“This highlights a lot of the things that we’ve seen with our current experience. . . . But I think it also highlights what we see in all patients who are critically ill and in the intensive care unit. Patients as a whole are at significantly high risk of seizures when they’re critically ill in the ICU,” says Richard Temes, a neurologist at Northwell Health in New York who was not involved in the study. “The only way that you detect these seizures oftentimes is by capturing the seizure activity on the EEG.”
Generally, if a patient in the hospital has altered mental status—a blanket term meaning that they’re confused or not functioning as well as their healthcare providers would expect—physicians hook them up to an EEG to monitor for seizures or irregular activity. Seizures have the potential to cause brain damage and can be triggered by stress or disease, so monitoring a patient’s brain waves can tell clinicians if they need to treat the patient with antiepileptic drugs or reduce stimuli to prevent damage.
Maybe what this tells us, is that seizures in these patients is not COVID attacking the brain or causing brain disease. This is because of the severity of the disease or the severity of the hypoxia.—Maria Bruzzone, University of Florida
Early in the pandemic, “a lot fewer people were getting brain monitoring,” than normally would in hospitals, says Brandon Westover, a neurologist at Massachusetts General Hospital and an author of the study. He attributes the decrease to the shortage of personal protective equipment (PPE), which meant that providers tried to limit the number of times they’d enter a patient’s room. “Because of what was happening at the time, only the sickest patients” were monitored with an EEG, says coauthor Mouhsin Shafi, a neurologist at Beth Israel Deaconess Medical Center in Boston, so it’s still not clear how common EEG abnormalities may have been in other patients.
The team started the project in the spring of 2020, just as the virus took hold in the US, and recruited scientists from a consortium of institutions that work together to compile health data. At first, the researchers suspected that it would be a “small, quick project, probably boring,” says Westover. At the time, “we thought this was a purely respiratory syndrome.”
But as the pandemic raged on, it became clear that the virus is able to affect tissues throughout the body and that cognitive effects, from confusion to strokes, are common. Last week, for instance, a study in The Lancet Psychiatry showed that one-third of patients were diagnosed with a neurological or psychological condition within six months of contracting COVID-19.
Westover’s group collected data on 197 patients hospitalized with COVID-19, 19 of whom experienced nonconvulsive seizures. Patients who experienced the seizures were four times more likely to die in the hospital than were their counterparts with similarly severe disease but no seizures.
In addition to the patients who experienced seizures, 48.7 percent of the patients showed epileptiform discharges, which Shafi describes as “little sparks of epileptic activity lasting less than a second.” In some cases, these sparks can cause damage, while other times they serve as a sign that a patient’s brain is not functioning normally and may be at a higher risk for seizures. Westover says that he was “shocked” by the epileptic discharges. “We were betting on less than five percent” of patients experiencing these types of abnormalities, he explains. Their prevalence may suggest that COVID-19 affects the brain more than scientists currently know.
“We were waiting for a study like this because we didn’t have much information on a bigger scale on what was going on physiologically in the brain of a patient that has COVID,” says Maria Bruzzone, a neurologist at the University of Florida who was not involved in the study.
The number of seizures was similar to what would be expected for patients hospitalized with other illnesses. “Maybe what this tells us,” says Bruzzone, “is that seizures in these patients is not COVID attacking the brain or causing brain disease. This is because of the severity of the disease or the severity of the hypoxia.”
Fred Lado, a neurologist at Northwell Health agrees, adding that it’s important to note that the patients in this study were all evaluated in the first few months of the pandemic. “Now those outcomes might have been better because we managed the COVID better,” he says.
The researchers propose that it will be important to monitor long-haul COVID-19 patients with ongoing cognitive symptoms such as depression or brain fog to see if nonconvulsive seizures or abnormal rhythms are playing a role. “The next big question is, to what extent do these epileptiform abnormalities contribute to the cognitive problems that people have going when they go home?” says Westover. “And then what should we be doing?”
L. Lin et al., “Electroencephalographic abnormalities are common in COVID-19 and are associated with outcomes,” Ann Neurol, doi:10.1002/ana.26060, 2021.