Highlights 20 patients with persistent neuromuscular symptoms including fatigue, 77–255 (median: 216) days after acute COVID-19 were examined. Nerve oncduction studies did not show signs of neuropathy but 11 patients (55%) had myopathic changes with quantitative electromyography. Myopathy may be an important cause of physical fatigue and myalgia in long-term COVID-19 even in non-hospitalized patients. Abstract Objective: To investigate the peripheral nerve and muscle function electrophysiologically in patients with persistent neuromuscular symptoms following Coronavirus disease 2019 (COVID-19). Methods: Twenty consecutive patients from a Long-term COVID-19 Clinic referred to electrophysiological examination with the suspicion of mono- or polyneuropathy were included. Examinations were per- formed from 77 to 255 (median: 216) days after acute COVID-19. None of the patients had received treat- ment at the intensive care unit. Of these, 10 patients were not even hospitalized. Conventional nerve conduction studies (NCS) and quantitative electromyography (qEMG) findings from three muscles were compared with 20 age- and sex-matched healthy controls. Results: qEMG showed myopathic changes in one or more muscles in 11 patients (55%). Motor unit potential duration was shorter in patients compared to healthy controls in biceps brachii (10.02 ± 0.28 vs 11.75 ± 0.21), vastus medialis (10.86 ± 0.37 vs 12.52 ± 0.19) and anterior tibial (11.76 ± 0.31 vs 13.2 6 ± 0.21) muscles. All patients with myopathic qEMG reported about physical fatigue and 8 patients about myalgia while 3 patients without myopathic changes complained about physical fatigue. Conclusions: Long-term COVID-19 does not cause large fibre neuropathy, but myopathic changes are seen. Significance: Myopathy may be an important cause of physical fatigue in long-term COVID-19 even in non-hospitalized patients. J. Agergaard a, S. Leth b, T.H. Pedersen c, T. Harbo d, J.U. Blicher d,e, P. Karlsson f, L. Østergaard a,H. Andersen d, H. Tankisi g,⇑ Link
