key: cord-0789882-17zxfphj
authors: Kushlaf, Hani
title: COVID‐19 in muscle‐specific kinase myasthenia gravis: A case report
date: 2020-08-02
journal: Muscle Nerve
DOI: 10.1002/mus.27020
sha: ccd6f187ee1393ba13e9230d932786f26c1296cd
doc_id: 789882
cord_uid: 17zxfphj

nan

disease-2019 (COVID-19). We report the clinical course of COVID-19 focusing on the MG postintervention status in this patient. The patient, a 66-year-old woman, was diagnosed with MG at 44 years of age. At the time of initial MG diagnosis, she presented with dysphagia, dysarthria, ptosis, and diplopia. Symptoms worsened, with difficulty walking and culminated in respiratory muscle weakness necessitating mechanical ventilation.

The diagnosis of MG was confirmed with a positive edrophonium test. Antibody testing 7 years earlier revealed a negative acetylcholine receptor-binding antibody and a positive MuSK antibody. She was initially treated with plasmapheresis, prednisone, and pyridostigmine. Subsequently, azathioprine was started while prednisone was tapered. Prednisone was stopped 5 years after diagnosis, and she had been in pharmacological remission since that time. Comorbidities were diabetes, warfarin anticoagulation for the history of deep venous thrombosis, and chronic kidney disease. She presented to the emergency department with fever and shortness of breath. Polymerase chain reaction testing for severe acute respiratory syndrome coronavirus-2 was positive. Examination in the emergency department showed no ptosis, diplopia, facial, bulbar, or limb weakness. Chest X ray revealed perihilar and ill-defined peripheral and lower zone predominant opacities. Arterial blood gas (ABG) before intubation showed hypoxemia without hypercapnia (partial pressure of oxygen 77 mmHg, partial pressure of carbon dioxide 34 mmHg, pH 7.43, bicarbonate 22 mEq/L). She was intubated for hypoxemic respiratory failure. Her hospital course was also complicated by hypotension and acute renal failure for which she was placed on continuous renal replacement therapy followed by intermittent hemodialysis. COVID-19 was treated with hydroxychloroquine for 5 days, tocilizumab, and intravenous immunoglobulin (IVIg) 1 g/kg daily for 2 consecutive days. We avoided azithromycin as a COVID-19 treatment due to its potential for exacerbating MG. We adjusted the dose of azathioprine according to the patient's renal status. She slowly improved and was extubated after 17 days then discharged to inpatient rehabilitation. After extubation, negative inspiratory pressure measurements were normal (−60 cmH 2 O) with frequent monitoring. As of this writing, at 2.5 months after extubation, she has continued to receive intermittent hemodialysis for renal failure and has not developed any symptoms suggestive of worsening of MG.

A recent report on patients with myasthenia gravis and COVID-19 included one patient with MuSK MG who had worsening of MG as a result of the COVID-19, and was treated with an increased dose of prednisone and with IVIg. Mechanical ventilation was not needed. 1 Our patient did not have ptosis, diplopia, bulbar, or limb weakness before intubation or after extubation. Also, we did not measure forced vital capacity or maximal inspiratory and expiratory pressures in the emergency department due to absence of symptoms and signs of MG exacerbation. The lack of hypercapnia on ABG before intubation suggests that the patient did not develop respiratory muscle weakness; however, we cannot entirely rule out subtle MG worsening in the intensive care unit due to inherent difficulties in assessing sedated and ventilated patients.

Moreover, the treatment of our patient with IVIg for COVID-19 may have masked symptoms of MG exacerbation. The normal measurements of negative inspiratory pressure after extubation suggested no respiratory muscle weakness.

Our case report lends support to individualized therapy of MG in the context of COVID-19 and is consistent with published guidance for the management of MG during the COVID-19 pandemic. 2 

COVID-19 in patients with myasthenia gravis

Guidance for the management of myasthenia gravis (MG) and Lambert-Eaton myasthenic syndrome (LEMS) during the COVID-19 pandemic