Course and Outcomes of COVID-19 in Series of Patients with Myasthenia Gravis
Key findings
- This case series describes five patients with pre-existing myasthenia gravis who were hospitalized for COVID-19: three who developed hypoxemic respiratory failure and two who did not
- One patient had a myasthenic exacerbation at the time of presentation, two had no exacerbation and two were intubated, which limited the ability to judge worsening myasthenic weakness
- A patient on maintenance intravenous immunoglobulin had that medication continued during hospitalization; three patients on mycophenolate mofetil at home had that medication transiently held with no apparent ill effects
- Four of the five patients were discharged; at the time of this report the other remained on mechanical ventilation
Neurologic sequelae of COVID-19 include cerebrovascular events, impaired consciousness, skeletal muscle injury and meningoencephalitis. In addition, like other infectious diseases, COVID-19 can trigger exacerbations of myasthenia gravis (MG) that result in neuromuscular respiratory failure.
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In Muscle & Nerve, Amanda C. Guidon, MD, director of the Myasthenia Gravis Clinic in the Department of Neurology at Massachusetts General Hospital, and Pria Anand, MD, of Boston University Medical Center (BMC), and colleagues report the clinical course and outcomes of five patients with MG who receive MG care at either Mass General or BMC and were hospitalized for COVID-19.
Myasthenic Exacerbation
Four of the patients had acetylcholine receptor antibodies and one had muscle-specific tyrosine kinase antibodies. The latter patient, who previously had well-controlled MG, had a myasthenic exacerbation characterized by worsening dysphagia, neck weakness and diplopia. The exacerbation was treated with intravenous immunoglobulin and an increased dose of steroids.
Three patients required respiratory support. One was put on high-flow oxygen and two were intubated and sedated, limiting the ability to detect worsening myasthenic weakness. However, none of these patients had a definite new or worsening weakness to support a myasthenic exacerbation.
The fifth patient had neither respiratory failure nor worsening myasthenic weakness.
Drug Treatment of MG
The article gives details of each patient's home immunosuppressive regimen and how it was changed during hospitalization. A patient on maintenance intravenous immunoglobulin had that medication continued during hospitalization. Hydroxychloroquine was used at the beginning of the pandemic before any trial data was available.
Three patients on mycophenolate mofetil at home had that medication transiently held. The impact of short-term discontinuation is unclear, as studies suggest mycophenolate mofetil may remain active for up to six weeks after cessation.
Drug Treatment of COVID-19
The three patients with respiratory failure received investigational COVID-19 therapies. One patient, who had a history of myasthenic crisis, received hydroxychloroquine, azithromycin and tocilizumab. The other two patients received hydroxychloroquine, azithromycin and ceftriaxone.
Outcomes
- Patient with respiratory failure and history of myasthenic crisis: Discharged on hospital day 9 without clear evidence of a myasthenic exacerbation
- Other patients with respiratory failure: The patient who was put on high-flow oxygen, age 90, was discharged to skilled nursing on hospital day 19; at the time of the report the other patient required ongoing mechanical ventilation
- Patients without respiratory failure: Discharged on hospital day 5 or 9
Clinical Takeaways
- In patients with COVID-19, clinicians may need to use bedside respiratory mechanics to evaluate for neuromuscular respiratory weakness with caution because of potential risk of aerosolization of viral particles and viral transmission
- In patients who are intubated, spontaneous tidal volumes can be used as a proxy respiratory muscle strength and as part of the neurologic examination: the predicted normal value is 5 mL/kg, and significantly lower values suggest some contribution of neuromuscular respiratory failure
- Unless hydroxychloroquine and azithromycin become standard care for COVID-19, they should be avoided or used with caution given the potential to worsen myasthenic weakness
- As suggested by recently released expert consensus guidelines, decisions about continuing immunosuppression and initiating acute interventions should be made on a case-by-case basis, based on the relative severities of COVID-19 and MG
The International Myasthenia Gravis/COVID-19 Working Group and the Myasthenia Gravis Rare Disease Network have developed an open registry to track outcomes of COVID-19 of any severity in patients with MG.
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