The patient, a 65-year-old woman with a medical history of kidney cancer, pituitary tumor, and a blockage in the pulmonary artery in the lungs, ultimately was successfully treated, though residual COVID-19 and ocular MG symptoms were found upon later re-evaluation.
The report, “New onset of ocular myasthenia gravis in a patient with COVID-19: a novel case report and literature review,” was published in the Journal of Neurology.
MG is caused by the immune system targeting the body’s muscle cells, impairing their communication with nerve cells. Most commonly, this immune attack is driven by antibodies that target a protein called acetylcholine receptor (AChR).
Infections can trigger an MG crisis in people with pre-existing disease, but whether they can be a cause of MG itself remains unclear.
COVID-19 is caused by the novel coronavirus SARS-CoV-2. Given how recently this virus was discovered, researchers are still gathering information about the common and less common effects it can have on the human body.
Now, clinicians are reporting the case of an older patient with a history of renal cell carcinoma (kidney cancer), pituitary adenoma, and pulmonary embolism who developed ocular MG secondary to COVID-19.
The patient went to the hospital after experiencing two weeks of diarrhea, muscle pain, and extreme fatigue, as well as three days of ptosis, or drooping, of the left eyelid. At the time, she was not experiencing shortness of breath. Upon physical examination, the patient was noted to have diplopia, or double vision.
She had previously been exposed to COVID-19 via a family member. A nasopharyngeal RT-PCR swab test (nasal swab) confirmed a diagnosis of COVID-19.
Additional laboratory tests revealed elevated levels of inflammatory markers in the blood. The woman also had high levels of anti-AChR antibodies: hers were 7.39 nanomoles (nmol)/L, while normal levels are less than 0.02 nmol/L.
On day two of hospitalization, the patient had an electromyography, which is a diagnostic procedure to assess the health of muscles and the nerve cells that control them. That procedure showed evidence of impaired muscle-nerve communication around the patient’s left eye.
“Based on the combination of findings from history, laboratory investigations and electrodiagnostic testing, she was diagnosed with seropositive [detectable antibodies] ocular myasthenia gravis,” the researchers wrote.
On her third day in the hospital, the patient started treatment with pyridostigmine, an approved MG medication marketed under the brand name Mestinon, among others. This eased her ptosis and diplopia. She was then discharged from the hospital, with instructions to self-quarantine while continuing on pyridostigmine. A follow-up clinic visit was planned for six weeks later.
However, a few days after being discharged, the woman developed nausea, diarrhea, and a loss of taste and smell. Ultimately, she returned to the clinic due to septic shock — when a bodywide infection leads to dangerously low blood pressure — and required supplemental oxygen due to difficulty breathing.
At first, it was unclear whether these symptoms were related to MG, a side effect of the pyridostigmine therapy, or due to COVID-19. However, clinical examination, combined with the fact that symptoms such as diarrhea were not present when the patient started on pyridostigmine, suggested COVID-19 as the most likely cause.
She continued on pyridostigmine at a reduced dosage, and was also treated with dexamethasone — a steroid used to reduce inflammation.
The patient continued to have mild drooping of the eyelid, but no further double vision or any severe muscle weakness. After 10 days in the hospital, she was able to be weaned off of supplemental oxygen, without shortness of breath or cough. Residual symptoms of COVID-19 and ocular MG were found upon re-evaluation a month later.
However, “to our knowledge, this is the first reported case of ocular MG in a patient infected with COVID-19,” the scientists wrote.
As for how an infection such as COVID-19 could lead to MG, the scientists said that immune attacks against the coronavirus could inadvertently target the connection between nerves and muscle.
“It is possible that the MG manifestation in the patient may be a specific complication of the COVID-19 infection or a post-infectious emergence of MG,” they said.
“However,” they added, “it should be noted that conclusions drawn from a single case are limited and can only suggest association. Observations from further cases will be needed to consolidate our findings.”
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