Myasthenia gravis complicated by the development of COVID-19: an analysis of case series
Authors: Marchuk M. S. , Zinchenko M. S. , Sokolova L. I. 
Published: December 2022

Myasthenia gravis (MG) is an autoimmune disease characterized by increased dynamic muscleweakness. Patients with myasthenia gravis are united by the phenomenon of deterioration of the clinicalcondition after infection, refusal of treatment or taking certain medications, surgical intervention, exposureto heat and stress. In the context of the COVID‑19 (Coronavirus disease 2019) pandemic, the study ofpatients with myasthenia gravis and a new infectious disease may reveal new pathogenetic patterns andchange the therapeutic strategy.
Objective — to identify clinical and paraclinical, therapeutic regularities in patients with MG and COVID‑19.
Methods and subjects. From April 2021 to November 2021, the course of MG against the background ofCOVID‑19 in 11 patients was analyzed. The control group consisted of 7 patients with COVID‑19, butwithout MG. General clinical, neurological, instrumental, laboratory and statistical examination methods,scales Myasthenia Gravis Foundation of America (MGFA), The Quantitative Myasthenia Gravis Score (QMGS), Myasthenia Gravis Activities of Daily Living (MG‑ADL), The National Early Warning Score 2 (NEWS2) and questionnaires were used.
Results. In the experimental and control groups, the level of SpO2 when breathing atmospheric air wascorrelated with the presence of bronchial asthma (BA) (r = –0.791), diabetes mellitus (DM) (r = –0.553),hypertension (r = –0.301). A positive correlation (r = 0.271) was found between the presence of MG and the level of SpO2 when breathing atmospheric air, which may be associated with the intake of pyridostigmine anda decrease in muscle mass in patients with MG. Presence of a relationship between the NEWS2 indicatorwith DM (r = 0.501), BA (r = 0.483), obesity (r = 0.376), hypertension (r = 0.352), multinodular goiter (r = 0.204), hydrothorax (r = 0.204) and MG (r = 0.120). In the myasthenia group, a relationship was established between the duration of treatment for COVID‑19 and body mass index (BMI) (r = 0.523), age (r = 0.504), pyridostigmine intake (r = –0.243) and weight (r = 0.228). NEWS2 in the experimental group was correlated with pyridostigmine intake (r = –0.386), weight (r = 0.355) and BMI (r = 0.256). Duration of treatment for COVID‑19 was associated with duration of MG (r = 0.570), obesity (r = 0.572), and BMI (r = 0.526). NEWS2 is related to the level of SpO2 when breathing atmospheric air (r = — 0.907), hemoglobin (r = –0.847) and vital capacity of the lungs (VC) (r = –0.699). Obesity (r = 0.787), anemia (r = 0.684) and BA were correlated with NEWS2. The finding of an inverse correlation between NEWS2 and pyridostigmine intake (r = –0.684) was promising. Soft palate paresis (r = –0.614), dysphagia (r = –0.614) and nasality (r = –0.545) were correlated with a decrease in VC. A correlation was found between VC and the NEWS2 (r = –0.699). The duration of COVID‑19 (r = –0.646) and patient age (r = –0.626) were correlated with VC.
Conclusions. MG with the addition of COVID‑19 tends to worsen the course, progress of muscle weakness,development of respiratory failure and hypoxia. Aggravating factors are age, duration of MG, duration ofCOVID‑19, BMI, concomitant pathology (DM, hypertension, BA, obesity, anemia). Constitutional features(lower BMI and weight) may contribute to shortening the duration of treatment. Taking pyridostigmineallows to reduce not only the duration of treatment, but also the risk of worsening of the condition, whichmay be associated with the suppression of the inflammatory process when taking an anticholinesteraseagent.