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Introduction: Since the onset of the novel coronavirus pandemic, several neurological complications secondary to SARS‐CoV‐2 infection have been reported, affecting central nervous system, peripheral nervous system and neuromuscular junction. Case report: We present the case of a 77‐year‐old man who developed bulbar myasthenia gravis (MG) eight weeks after SARS‐CoV‐2 infection. The search for serum antibodies against the acetylcholine receptor and the muscle‐specific tyrosine kinase (MuSK), performed by radioimmunoassay (RIA), and the search of low‐density lipoprotein receptor‐related protein 4 antibodies, performed by immunohistochemistry, resulted negative, while anti‐MuSK antibodies were detected by cell‐based assay (CBA). The patient was treated with pyridostigmine (60 mg four times a day) with unsatisfactory clinical response, followed by immunosuppressive therapy (azathioprine 1.5 mg/kg/day) with improvement of MG symptoms after two months of treatment. Discussion: Several viral diseases have been described as associated with the onset of MG, although the underlying mechanisms are not yet fully understood. Similarly, a growing number of scientific reports suggest a correlation between SARS‐CoV‐2 infection and autoimmune diseases. The interest of our case lies in the timing of the MG onset (after 2 months from infection), together with the unusual late onset of anti‐MuSK MG. These elements suggest that coronavirus infection may act as a trigger of the disease. We confirm the importance of CBA in the serological diagnosis of RIA‐negative MG. [ABSTRACT FROM AUTHOR]

Objective: Myasthenia gravis (MG) is an autoimmune neuromuscular disorder for which current therapies carry a high risk of side-effects and may be insufficient in stabilizing the clinical status. Many therapeutic options can be ruled, such as thymectomy, corticosteroids, azathioprine, cyclophosphamide, mycophenolate mofetil, methotrexate, intravenous immunoglobulin (IVIg) or less frequently plasmapheresis must be ruled. Methods: We followed prospectively six patients with MG who presented with a poor response to two or three lines of immunosuppressive conventional drugs associated with oral corticosteroids. All but one were acetylcholine receptor negative and three were anti-MuSK positive. IVIg did not improved the neurological status and all patient required high doses of cholinesterase inhibitors. Results: Rituximab was introduced with a mean follow-up of 1.5 years (375 mg/m2, days 1, 8, 15, 28 during the first month and then one dose every 2 months). After 2 years of follow-up, all patients stopped corticosteroids and tapered off cholinesterase inhibitors from 60 to 180 mg/day without severe infectious events. Conclusion: Rituximab, a chimeric IgG k monoclonal antibody that target CD20 is used for the treatment of relapsing/refractory CD20 positive low-grade non-Hodgkin’s lymphoma and other autoimmune neuromuscular diseases. Four previous short reports have described a good response of MG associated with lymphoma with rituximab. It appears to be a promising and effective drug for the treatment of MG without lymphoma, with a substantial benefit to the clinical status and good tolerability. [ABSTRACT FROM AUTHOR]