Among the many serious symptoms of COVID-19, the strange neurological effects that many patients experience count as perhaps the most mysterious.
A sudden loss of smell and taste was one of the first unusual symptoms reported by COVID-19 patients, but stroke, seizures and swelling of the brain (called encephalitis) have all been described.
Some patients diagnosed with COVID-19 also experience confusion, delirium, dizziness and have difficulty concentrating, according to case reports and reviews.
For months, doctors have been trying to understand this disease and its many manifestations that appear to affect the brain in ways we cannot fully explain.
To synthesize some of the rapidly accumulating data, two neurologists have now conducted a review of research examining how COVID-1
An EEG, short for electroencephalogram, records electrical activity in different parts of a person’s brain, typically using electrodes placed in their scalp.
In their review, the researchers collected data on nearly 620 COVID-positive patients from 84 studies published in peer-reviewed journals and pre-print servers where EEG waveform data were available for analysis.
Looking at EEG results could indicate some form of COVID-related encephalopathy in these patients – signs of impaired or impaired brain function.
Approx. two-thirds of the patients in the studies were men and the median age was 61 years. Some people also had a pre-existing condition, such as dementia, that could alter an EEG reading, which the researchers considered when evaluating their test results.
Among the 420 patients in whom the basis for ordering an EEG was recorded, the most common cause was a changed mental state: close to two-thirds of the patients examined had experienced some delirium, coma or confusion.
About 30 percent of patients had had a seizure-like event that prompted their doctor to order an EEG, while a handful of patients had speech problems. Others experienced a sudden cardiac arrest that could have disrupted blood flow to the brain.
Patients’ EEG scans showed a full range of abnormalities in brain activity, including some rhythmic patterns and epileptic-like spikes in activity. The most commonly observed abnormality was diffuse deceleration, which is a total deceleration of brain waves indicating a general dysfunction in brain activity.
In the case of COVID, this weakening may be the result of widespread inflammation, as the body mounts its immune response or possibly reduced blood flow to the brain if the heart and lungs are weak.
In terms of localized effects, one-third of all detected abnormalities were detected in the frontal lobe, the part of the brain that handles executive thinking, such as logical reasoning and decision-making. The frontal lobe also helps us regulate our emotions, control our behavior and is involved in learning and attention.
“These findings tell us that we need to test EEG on a wider range of patients as well as other types of brain formation, such as MRI or CT scans, which give us a closer look at the frontal lobe,” said neurologist and co-author Zulfi Haneef from Baylor College of Medicine in Houston.
Over time, an EEG could help cement a COVID-19 diagnosis or suggest possible complications. This may help physicians monitor the long-term complications of COVID-19 and detect any long-term effects on a patient’s brain function.
Unfortunately, as it turns out, the results give no indication of how rare or common these brainwave disorders are in the wider population, as only COVID-19 patients who had an EEG test were included in the analysis.
But it adds to the growing evidence that the new coronavirus can have a serious impact on our neurological health.
“More research is needed, but these findings show us that these are areas we need to focus on as we move forward,” Haneef said.
“EEG abnormalities affecting the frontal lobe appear to be common in COVID-19 encephalopathy and have been suggested as a potential biomarker if detected consistently,” the authors wrote in their paper.
As the pandemic continues, we have come to understand how stubborn COVID-19 can be, where patients called ‘long-distance carriers’ describe how they can not shake the symptoms and still feel tired months after being diagnosed.
“Many people think they will get the disease, get well, and everything will go back to normal,” Haneef said in a statement.
“But these findings tell us that there may be long-term problems, which we suspect, and now we find more evidence to back it up.”
The study was published in Seizure: European Journal of Epilepsy.