Reduced TMS-evoked EEG oscillatory activity in cortical motor regions in patients with post-COVID fatigue

Objective: Persistent fatigue is a major symptom of the so-called 'long-COVID syndrome', but the pathophysiological processes that cause it remain unclear. We hypothesized that fatigue after COVID-19 would be associated with altered cortical activity in pre- motor and motor regions. Methods: We used transcranial magnetic stimulation combined with EEG (TMS-EEG) to explore the neural oscillatory activity of the left primary motor area (l-M1) and supplementary motor area (SMA) in a group of sixteen post-COVID patients complaining of lingering fatigue as compared to a sample of age- matched healthy controls. Perceived fatigue was assessed with the Fatigue Severity Scale (FSS) and Fatigue Rating Scale (FRS). Results: Post-COVID patients showed a remarkable reduction of beta frequency in both areas. Correlation analysis exploring linear relation between neurophysiological and clinical measures revealed a significant inverse correlation between the individual level of beta oscillations evoked by TMS of SMA with the individual scores in the FRS (r(15) =-0.596; p = 0.012). Conclusions: Post-COVID fatigue is associated with a reduction of TMS-evoked beta oscillatory activity in SMA. Significance: TMS-EEG could be used to identify early alterations of cortical oscillatory activity that could be related to the COVID impact in central fatigue. (c) 2024 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.