A practical value of systematic reviews and meta-analyses on prevalence of EEG abnormalities in COVID-19

Abstract

During the COVID-19 pandemics, the amount and volume of electroencephalographic (EEG) examinations have been limited for safety reasons. This has complicated not only an identification of specific EEG correlates of the disease but also an assessment of non-specific EEG changes in pa- tients with COVID-19, raising the question of detection of factors and the degree of their impact on prevalence of EEG abnormalities in COVID-19. In the PubMed database, three meta-analyses and three systematic reviews were selected on keywords “COVID-19”, “EEG”, “systematic review”, and “meta-analysis” in order to compare values of the prevalence of EEG abnormalities in patients with COVID-19. The systematic reviews and meta-analyses, which had been performed since 2020 and assessed the prevalence of EEG abnormalities in patients with COVID-19, had differences in their final results despite of an application of the same mathematical methods, criteria for classification of phenomena, usage of one limited base of sources with EEG results (the percentage of overlapped outcome data in the selected reviews and meta-analyses ranged from 22 % to 100 %). Differences between works, which were included in this article, on qualitative and quantitative values of degree of brain functional activity changes in a part of patients with COVID-19 have a sufficiently random nature due to not only volumes of the samples, but also a number of other subjective and objec- tive factors. The results of the presented systematic reviews and meta-analyses suggest, that not all of the obtained EEG data might be extrapolated on a cohort of patients with COVID-19, as the vast majority of patients with COVID (from 85 % to 100 %) examined with EEG had non-specific EEG-changes of a various genesis. A detection of the prevalence of non-specific EEG abnormalities in COVID-19 could have practical implication, particularly for prognosis of outcomes, only on condition of EEG analysis in samples of patients united by a certain common criterion, such as age, presence of certain neurological symptom/syndrome, specific neurological pathology in their anamnesis, etc.