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Case Shows Difficulty of Diagnosing Myasthenia Gravis Following COVID-19

The patient, an 83-year-old man, experienced onset of myasthenia gravis after a severe SARS-CoV-2 infection.

COVID-19 can lead to a number of potential health complications, but a new case report highlights how the virus can also make it harder to differentiate symptoms caused by the virus from those caused by other conditions.

The report, published in Cureus, describes an 83-year-old man who began experiencing symptoms of myasthenia gravis (MG) about a month after he had been hospitalized with COVID-19–related pneumonia. The investigators said his diagnosis was delayed because the autoimmune disease has symptoms that are similar to those of COVID-19.

The study authors explained that MG affects patients’ neuromuscular junction, leading to symptoms ranging from ocular problems to muscle weakness that can impair swallowing, chewing, and breathing.

In the case report, the patient had a history of cardiovascular concerns, including atrial fibrillation and trigeminal neuralgia. He was initially hospitalized with COVID-19–associated acute respiratory failure in December 2020 and was admitted to the hospital’s intensive care unit. His COVID-19 was treated in the hospital with remdesivir (Veklury) and convalescent plasma therapy, and he was discharged after 17 days. However, his healthcare saga was not over.

“A month after discharge, he started experiencing significant fatigue with muscle weakness and progressive dyspnea,” the investigators reported.

An echocardiogram showed moderate to severe mitral regurgitation, and so doctors initially believed that was the cause of his dyspnea.

“However, his fatigue continued to progress,” the investigators said. “Due to a history of atrial fibrillation, a loop recorder was implanted, which did not show any increased atrial fibrillation burden contributing to his fatigue.”

His weakness continued and speech problems developed over the next several months. Finally, in September 2021, he returned to the hospital with acute hypoxemic respiratory failure. He was intubated and put on a mechanical ventilator. By that point, clinicians suspected aspiration pneumonia and possibly angiotensin receptor inhibitor–induced angioedema, study investigators said. He was given antibiotics and methylprednisolone; the latter was tapered over 5 days and was weaned off the ventilator. However, his dysarthria and dysphagia soon worsened.

“Post hospitalization, he was found to have orthostatic hypotension and bilateral fatigable ptosis,” the authors said. A laboratory workup for fatigue helped investigators finally land on a diagnosis of MG.

“The anti-acetylcholine receptor (anti-AChR) antibody was elevated at 0.26 nmol/L (reference: < 0.02 nmol/L), the anti-MuSK [muscle-specific tyrosine kinase] antibody was negative, and AChR modulating antibody flow cytometry was negative,” they wrote.

The patient was given a course of prednisone and referred to a neurologist, who prescribed 60 mg of prednisone every other day and 30 mg daily of pyridostigmine (Mestinon)—but the patient could not tolerate the latter and so he discontinued that medication. He then started on azathioprine (Imuran) at 50 mg twice daily and his steroid dose was tapered.

Azathioprine controlled the patient’s MG, but his heart failure worsened. After experiencing a decline in renal function and an infection, he died about a year after his MG diagnosis.

The authors said they were delayed in correctly diagnosing MG in the patient because it was difficult to know whether his muscle weakness had to do with his COVID-19, other comorbidities, or something else. They also noted that the patient had no family history of autoimmune or musculoskeletal disease. Thus, they said, patients like the one in this case require vigilance.

“Therefore, a high index of suspicion along with a low threshold for testing is required in individuals with difficulty in weaning off ventilators,” they said. “This should especially be sought out in those in whom the degree of clinical disease does not correlate with image findings not consistent with severe COVID-19 disease.”

The investigators said further research will be needed to better understand the pathophysiological links between the 2 conditions.

Reference

Chatterjee T, Senthil Kumaran S, Roy M. A case report and literature review of new-onset myasthenia gravis after COVID-19 infection. Cureus. Published online December 28, 2022. doi:10.7759/cureus.33048

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