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New-onset ocular myasthenia gravis following SARS-CoV-2 infection
Prabrisha Banerjee1, Haseeb Hassan2, Md Shahid Alam1
1 Orbit, Oculoplasty, Reconstructive and Aesthetic Services, Aditya Birla Sankara Nethralaya, Kolkata, West Bengal, India
2 Department of Neurology, Rabindranath Tagore International Institute of Cardiac Sciences, Kolkata, West Bengal, India
|Date of Submission||27-Jan-2022|
|Date of Decision||19-May-2022|
|Date of Acceptance||09-Aug-2022|
|Date of Web Publication||26-Dec-2022|
Source of Support: None, Conflict of Interest: None
| Abstract|| |
SARS-CoV-2 involves multiple systems and has myriad clinical presentations. The onset of myasthenia gravis secondary to SARS-COV 2 has rarely been reported. We report the third case of ocular myasthenia gravis (OMG) following the COVID-19 infection. Molecular mimicry between the viral proteins and the acetylcholine receptor has been implicated in the pathogenesis of COVID-19–induced OMG. The patient responded well to the oral pyridostigmine therapy.
Keywords: COVID-19, cytokine dysregulation, myasthenia gravis, ocular myasthenia gravis, SARS-CoV-2
The novel coronavirus SARS-CoV-2 primarily affects the respiratory system and can produce severe acute respiratory syndrome. Case studies of the affected individuals have revealed an array of manifestations of the SARS-CoV-2 virus, including cardiovascular disease, acute renal injury, neurological disorder, coagulopathy, and elevated inflammatory markers. Myasthenia gravis (MG) is an autoimmune disease, in which antibodies are directed against the acetylcholine receptors (Ach-Rs) at the postsynaptic neuromuscular junction. Viral infections have already been found to be a predisposing factor for MG. The emergence of SARS-CoV-2 has not only witnessed an exacerbation of previously diagnosed and stable cases of MG but also new-onset MG. We herewith report the third case of isolated new onset OMG following SARS-CoV-2 infection. A 47-year-old Indian male presented to our clinic with complaints of drooping of both eyelids (left > right), with diurnal variation and occasional binocular double vision for the past 10 days. He gave a history of acquiring SARS-CoV-2 infection 1 month back. The infection was mild, and he recovered fully after 3 weeks of home isolation. His serum C-Reactive protein marker was raised. On examination, his best-corrected visual acuity was 20/20, N6 in both the eyes. Both eyes had variable ptosis with the left eye showing more drooping than the right [Figure 1]a. The ocular motility was full and free. The fatigue test and the Cogan's lid twitch sign were positive in both eyes, and an ice test showed marked improvement in ptosis [Figure 1]b. The serum level of antibodies against Ach-R was elevated (>8 nmol/L), and repetitive nerve stimulation at a low rate (3 Hz) showed a decremental response. Computed tomography of the chest ruled out the presence of a thymoma. He was administered oral pyridostigmine (60 mg thrice daily) under the supervision of a neurologist. A month later, in his follow-up visit, a good clinical response was observed to treatment. OMG is a localized form of autoimmune disorder characterized by antibodies against the Ach-Rs at the postsynaptic neuromuscular junction. The viral agents that have been implicated in MG are varicella, West Nile virus, and Zika virus., This is the third case of new-onset OMG following SARS-CoV-2 infection. The underlying pathogenesis postulated in COVID-19–induced MG is the cross-reaction of the antibodies produced against the virus with the Ach-R, due to molecular mimicry between the latter and the SARS-CoV-2 proteins. Moreover, on account of its affinity toward angiotensin-converting enzyme 2, it leads to activation of the inflammatory cascade which results in the production of autoantibodies. Compared to the reported cases, our case developed ocular symptoms a little later, after 2 months of COVID-19 infection. By and large, all the COVID-19–induced OMG cases including this patient had demonstrated elevated serum levels of anti-Ach-R antibodies. Viral infection, in general, is a predisposing factor of MG crisis. Besides the cytokine dysregulation in COVID-19, the other contributory factors for SARS-CoV-2–related MG crisis are pandemic-induced stress, insomnia, anxiety, and hydroxychloroquine (directly known to cause MG) and the nonavailability of drugs during the lockdown. The stress caused by the pandemic triggers the inflammatory cascade. However, none of these factors were contributory in our case.
|Figure 1: (a) Mild ptosis in the right eye and severe ptosis in the left eye of the patient. (b) Resolution of bilateral ptosis after ice test|
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Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initial s will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed
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Conflicts of interest
There are no conflicts of interest.
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