Post-COVID-19 mononeuritis multiplex: a potential complication in severe SARS-CoV- 2 infection survivors

Background: Neuromuscular involvement has been identified in acute and early stages of severe COVID-19. Guillain-Barre syndrome and variants, rhabdomyolysis and prone position-related neuropathy represent early complications. Mononeuritis multiplex is rarely a post-infectious complication. Objectives: Characterization of patients with mononeuritis multiplex after severe COVID-19. Methods, design and setting: We performed a retrospective observational study of clinical, laboratorial and neurophysiological aspects of nine Brazilian patients with mononeuritis multiplex after severe COVID-19 at the Division of Neuromuscular Diseases, Federal University of São Paulo (UNIFESP), São Paulo, Brazil. Results: Nine patients (4 male, 5 female) had mean age at diagnosis of 60.6 years. 78% had at least one risk factor for severe COVID-19. Dyspnea, cough, fever, headache, anosmia, odynophagia, and myalgia were the most common SARS-CoV-2 symptoms. Most patients had large length of stay in intensive care (35.8 days), with orotracheal intubation and the need of prone positioning and tracheostomy. 44% had venous or arterial thromboembolic complications. Mononeuritis multiplex symptoms started after 45.7 days (23-71) of first COVID-19 symptoms. Sensorimotor multifocal axonal mononeuritis multiplex was the most common pattern (78%) with moderate to severe (89%) and lower limb-dominant compromise (67%). 33% with LANSS pain scale >12 and 67% with high fatigue scores on Fatigue Severity Scale. Two patients developed moderate titles of positive antinuclear antibody for nuclear membrane compounds (titin) during diagnostic work-up. Three patients were treated with oral corticosteroids with moderate disease control. Conclusions: Mononeuritis multiplex may be a late neuromuscular complication after severe COVID-19. Vasculitis and endotheliopathy seem to mediate its pathophysiology.