Evaluation of neuromuscular junction functions with single fiber electromyography in individuals with persistent fatigue after Coronavirus disease 2019

Abstract

Purpose: Post COVID Syndrome (PCS) is one of the most intriguing topics related to coronavirus disease 2019 (COVID-19). Fatigue is one of the most prevalent and disabling symptoms of PCS. In this study, we aimed to investigate the neuromuscular junction functions in people who have had long-term fatigue due to COVID-19 and to investigate whether the neuromuscular junction is the cause of fatigue. Methods: 37 patients who had COVID-19 at least 12 weeks ago and continued to complain of fatigue and 37 healthy individuals were included in the study. The Fatigue Severity Scale (FSS) and Fatigue Impact Scale (FIS) questionnaires were applied to people with fatigue. Single Fiber Electromyography (SFEMG) was applied to all individuals and the obtained data were compared between the two groups. Results: 70.3% of the patients with Post Viral Fatigue Syndrome (PVFS) had increased fatigue severity. 45.9% of the patients experienced mild fatigue, 35.1% of them experienced moderate fatigue, 13.5% experienced significant fatigue and 5.4% of them had severe fatigue according to FIS. The number of fibers with pathologically increased jitter and the mean jitter values of patients with PVFS were significantly higher than those of healthy individuals. 59.4% of patients with PVFS had moderate motor end plate dysfunction on SFEMG and 13.6% had apparent motor end plate dysfunction. Conclusion: Patients with PVFS caused by COVID-19 have neuromuscular junction dysfunction. It is unclear why these individuals are affected, but abnormal immune responses can lead to this dysfunction.