Neurological symptoms related to COVID-19 infection continues to gain evidence from researches conducted around the world.

New research released on Friday showed that almost 50% of all COVID-19 patients admitted to the intensive care unit (ICU) showed brain abnormalities on MRI scans. The study was published in Radiology, conducted by a team led by Dr. Naci Kocer, neuroradiology professor, at Istanbul University-Cerrahpasa.

The results of the study emphasized symptoms already identified in these patients. According to the paper, 6% of the patients experience acute stroke while another 15% developed an altered state of mind and scientists believe that cytokine storm could have also played a role in it.

According to the team, recent evidence underscores a relatively high percentage of central nervous system symptoms, especially to those patients with more severe respiratory diseases status.

Neurological Impacts of COVID-19

The researchers conducted magnetic resonance imaging (MRI) exams on COVID-19 patients in ICU who were admitted to 8 hospitals - including two academic and six non-academic-affiliated - to determine the neurological impacts of the virus.

Out of 235 patients who were receiving care in ICU, 50 or 21% of them developed neurological symptoms, in which 27 patients were examined under the brain MRI. Among those 27 patients imaged, 12 or 44% had acute findings.

Furthermore, ten patients had COVID-19-related neuroimaging findings which showed cortical FLAIR signal abnormalities, including an increased cortical diffusion-weighted signal with corresponding low ADC values, subtle leptomeningeal development, and punctuate cortical blooming artifact.

All these abnormalities were involved in different areas such as the frontal lobe, parietal lobe, occipital lobe, temporal lobe, insular cortex and cingulate gyrus.

The main differential diagnosis for this group of abnormalities is the infectious or autoimmune encephalitis, seizure, hypoglycemia, and hypoxia which can be accompanied by cortical microhemorrhages and blood-brain barrier breakdown.

According to the researchers, COVID-19 may result in infectious or autoimmune encephalitis because of its neurotropic potential. "Certain viral and autoimmune encephalitis can have a specific pattern of involvement that is helpful to establish a differential list, however non-specific imaging pattern in our series hinders achieving a specific diagnosis based on MRI," the researchers wrote.

Furthermore, cerebrospinal fluid samples (CSF) were collected in 5 out of 10 patients with cortical signal abnormalities. Four of them showed elevated protein levels, cell counts, glucal levels, IgG index, and albumin were normal; while RT-PCR for both herpes simplex virus and SARS-CoV-2, were negative.

Additionally, 15 cases did not show any COVID-19-related or acute intracranial findings during their MRI exam. Despite negative MRI images, two samples of CSF taken from this group showed elevated protein levels.

Comorbid Conditions Can Also be a Confounding Factor

The researchers noted that it is vital to include comorbid conditions, like diabetes mellitus, prolonged ICU stays, respiratory distress with hypoxia episodes as confounding factors in the neurological abnormalities mentioned.

Moreover, it is difficult to establish a clear cause-and-effect relationship between COVID-19 and the MRI findings without more specific CSF findings, which means that additional research is required.

The team of researchers wrote that their study might help increase awareness for a possible relationship between SARS-CoV-2 and neurological abnormalities seen on the infected patients, especially those receiving treatment in the ICU.