High prevalence of electroencephalographic frontal intermittent rhythmic delta activity in patients with moderately severe COVID-19

The aim of our study was to analyse EEG findings in patients with COVID-19 not requiring respiratory support. We reviewed EEGs performed in patients with COVID-19 between April 2020 and May 2021 at the University Hospital in Kraków, Poland. Demographic and clinical data, including comorbid conditions, discharge disposition, survival, neuroimaging findings, laboratory results, and treatment was collected. The study included 44 EEGs performed in 35 patients (51.4% females), aged 65.5 ± 13.9 years. Almost all patients had at least one comorbidity, and one-third had one or more preexisting neurological conditions. Three quarters of EEGs were abnormal. The most frequent EEG finding was background slowing (16 patients; 45.7%). Frontal findings included frontally predominant rhythmic delta (FIRDA) in 10 (28.6%) patients and focal slowing in the left frontal lobe. Patients with abnormal EEG significantly more often required oxygen supplementation (p = 0.003) and were less likely to recover (p = 0.048). Patients with COVID-19 infection may frequently manifest with an abnormal EEG. FIRDA seems to be a frequent EEG pattern in less severe cases of COVID-19 infection. Future studies are needed to establish whether COVID-19 infection increases the risk for FIRDA, and to investigate its pathogenesis.