Covid-19: Brain scans reveal a spectrum of abnormalities that cannot be fully explained

  • A new study, using EEG on Covid-19 patients, shows how the virus can have concerning impacts on the brain.
  • For the study, the researchers analysed data on patients across more than 80 studies.
  • The lead author states that some patients may experience irreparable brain damage, but that further research is required.

Covid-19 appears to be affecting the brain in ways that are not yet properly understood. A sudden loss of smell and taste and other strange neurological effects such as stroke, seizures and swelling of the brain (medically known as encephalitis) have all been described in previous case reports.

Some studies have also found confusion, delirium, dizziness and difficulty concentrating creeping up as some unusual experiences in patients.

Researchers from Baylor College of Medicine (BCU) and the University of Pittsburgh wanted to understand how exactly Covid-19 disturbs patterns of normal brain function, using an EEG (electroencephalogram).

An EEG is used to record brain activity and is performed by placing electrodes on a patient's scalp, and in this context could help indicate any Covid-related encephalopathy (signs of damage to brain function).

To do this, they collated and analysed the data of close to 620 Covid-19 patients from 84 studies that included the EEG waveform data. All these studies were published in peer-reviewed journals and preprint servers.

Their review was published in Seizure: European Journal of Epilepsy.

Altered mental status, seizures, cardiac arrest

The median age of Covid-19 patients assessed in the study was 61.3 years, and around two-thirds were male.

The researchers also considered that some patients had a pre-existing condition, such as dementia, that could alter their EEG reading.

The authors included the following results in 420 patients (where the basis for ordering an EEG was recorded), in their study:

  • Altered mental status, including delirium, coma or confusion (61.7 %)
  • Seizure-like events (31.2 %) 
  • Cardiac arrest (3.5%)

Some patients also experienced speech issues, the authors wrote. Overall, they noted, the patients' scans showed a whole spectrum of abnormalities in brain activity, with the most common abnormality being diffuse slowing (68.6%), which is an overall slowing of brain waves that indicate general cerebral dysfunction.

In addition to the above, the research team also found that "half of status epilepticus and focal slowing originated in the frontal lobes".

The frontal lobe, as explained in this Health24 article, handles emotions, logical reasoning, planning, movement, and parts of speech, and is also involved in attention and problem-solving.

Chance of irreparable brain damage

"These findings tell us that we need to try EEG on a wider range of patients, as well as other types of brain imaging, such as MRI or CT scans, that will give us a closer look at the frontal lobe," neurologist and co-author Zulfi Haneef from BCU in Houston said in a news release by the university.

Haneef added that some of the EEG alterations found in Covid-19 patients suggest damage to the brain that may not be able to be repaired after recovering from the disease.

"As we know, the brain is an organ that cannot regenerate, so if you have any damage, it will more than likely be permanent or you will not fully recover," he said.

Haneef also commented on another interesting finding. "We know that the most likely entry point for the virus is the nose, so there seems to be a connection between the part of the brain that is located directly next to that entry point.

"Another interesting observation was that the average age of those affected was 61, one-third were female and two-thirds were males.

"This suggests that brain involvement in Covid-19 could be more common in older males. More research is needed, but these findings show us these are areas to focus on as we move forward."

SARS-CoV-2 may not be directly responsible

The new coronavirus might, however, not be responsible for acting directly on the brain, causing the abnormal EEG readings, Haneef explained.

Instead, the effects could be due to a patient's oxygen intake, heart problems related to Covid-19 or another type of side effect. Because of this, he suggested comprehensive patient care should include more imaging of the brain or EEG testing as necessary.

"These findings tell us that we need to try EEG on a wider range of patients, as well as other types of brain imaging, such as MRI or CT scans, that will give us a closer look at the frontal lobe," Haneef said.

"A lot of people think they will get the illness, get well and everything will go back to normal, but these findings tell us that there might be long-term issues, which is something we have suspected, and now we are finding more evidence to back that up."

READ | How Covid-19 can affect your brain in 3 stages

READ | Covid-19 and loss of smell: Harvard researchers uncover why it happens

READ | Are Covid-19 survivors at heightened risk of PTSD?

Image: Getty/Science Photo Library

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