Subclinical myopathic changes in COVID-19

Villa, Davide; Ardolino, Gianluca; Borellini, Linda; Cogiamanian, Filippo; Vergari, Maurizio; Barbieri, Sergio

Background and aims: Coronavirus disease 2019 (COVID-19) is associated to neuromuscular symptoms in up to 10.7% of hospitalized patients. The prevalence and the characteristics of intensive care unit acquired weakness (ICUAW) in patients affected by COVID-19 have been extensively assessed, although no distinctive pattern was found. ICUAW has been described as a potential confounding factor during the identification of severe acute respiratory syndrome coronavirus 1-related myopathy. In order not to incur this potential bias, we focused on a subset of non-severe cases. Our aim was to precisely assess the extent of primary neuromuscular involvement with neurophysiological investigation in COVID-19 patients. Methods: From April through May 2020 a total of 70 patients were hospitalized in the Internal Medicine Ward of the Fondazione IRCCS Ospedale Maggiore Policlinico in Milan, Italy. After excluding patients who underwent invasive ventilation and steroid treatment, 12 patients were evaluated. Neurological examination, nerve conduction studies (NCS) and concentric-needle electromyography (EMG) were performed. Results: While nerve conduction studies were unremarkable, needle electromyography showed myopathic changes in 6 out of 12 subjects. All patients were asymptomatic for muscular involvement. Clinical features and laboratory findings did not show relevant differences between patients with and without myopathic changes. [Formula presented] [Formula presented] Conclusions: Our data show that in SARS-CoV-2 infection muscular involvement can occur despite the absence of clinical signs or symptoms and should be considered part of the disease spectrum. The application of muscle biopsy to unravel the mechanisms of myofiber damage on tissue specimens could help to clarify the pathogenesis and the treatment response of coronavirus-mediated injury.