Case Report and Review Examines MG and COVID-19

New research is highlighting rare cases in which patients with apparent subclinical myasthenia gravis (MG) experience symptom flares following immunization against SARS-CoV-2, the virus that leads to COVID-19.

However, the authors of the case report and review said such cases appear to be exceedingly uncommon and added that patients with MG still should be encouraged to get vaccinated. The report was published in International Journal of Environmental Research and Public Health.

MG is an autoimmune disease that is typically is characterized by autoantibodies targeting the acetylcholine receptor (AChR) of the neuromuscular junction, noted the study authors. Some patients have other antibodies against other targets besides AChR, and some have no detectable autoantibodies—and are known as seronegative MG (or SNMG) cases. Symptoms of the disease include fatigue and muscle weakness, but the location and strength of the symptoms can vary significantly among patients. In many cases, it begins as an ocular phenomenon, later transforming to a more generalized form. Some patients also have thymic dysfunction, and the presence of thymoma absent other thymic tumors is particularly associated with MG, the authors said.

In the new report, they describe the case of a 73-year-old man who was experiencing intermittent episodes of ptosis in his left eye, along with diplopia. The patient had a history of hypertension and type 2 diabetes, but he said he had never had ocular symptoms until recently.

At the time he presented for treatment, it had been 4 weeks since he had received his first COVID-19 vaccine dose. In his case, he received the Oxford-AstraZeneca ChAdOx1 vaccine. Although the patient’s symptoms were initially ocular, he experienced rapid clinical worsening of symptoms, and later received a diagnosis of generalized MG. A thoracic CT also showed a thymic mass that had not infiltrated surrounding structures. The patient was treated for his MG symptoms and had the mass surgically removed.

Eight months after his MG diagnosis, the patient took a Moderna vaccination dose without incident.

“One year after diagnosis, we observed a complete remission of neurological symptoms with oral azathioprine (Imuran) 100 mg and piridostimine (Mestinon) 225 mg, if we apply the World Health Organization causality assessment checklist,” they said.

The case prompted the study investigators to examine the existing literature in search of other instances in which MG appeared to onset following vaccination. They found 26 cases, 16 of which were considered “late-onset” cases, because the patients were 60 years or older at the time of symptom onset. Twenty of the patients were male, and the overall mean age was 60.8 years. The 73-year-old in the case report was the only patient with a thymoma, but 2 female patients had thymic hyperplasia. All but 3 of the patients tested positive for AChR autoantibodies.

The investigators cautioned that the number of people who experience the onset of MG symptoms following vaccination appears to be very small, given the massive numbers of people worldwide who have received a vaccine. They said it is not yet clear exactly what the link might be, if any, between the vaccine and the flaring of MG symptoms.

“Some of the reported cases probably already had the disease at a presymptomatic stage, and immunization only served as a co-factor,” they said.

They added that their data set was too small to draw any firm conclusions, and they said any risk associated with the vaccine would need to be balanced against the risks over COVID-19 infection.

“Nonetheless, clinicians should be aware that the presence of fatigability after SARS-CoV-2 immunization raises the suspicion of a MG diagnosis,” they said.

Reference

Virgilio E, Tondo G, Montabone C, Comi C. COVID-19 vaccination and late-onset myasthenia gravis: a new case report and review of the literature. Int J Environ Res Public Health. Published online December 27, 2022. doi:10.3390/ijerph20010467