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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]

Myasthenia gravis with antibodies to muscle-specific tyrosine kinase (MuSK-MG) is generally considered a severe disease because of the associated weakness distribution with prevalent involvement of bulbar muscles and a rapidly progressive course and early respiratory crises. Its treatment can be unrewarding, owing to poor response to acetylcholinesterase inhibitors in most patients, disease relapses in spite of high-dose immunosuppression, and development of permanent bulbar weakness. High-dose prednisone plus plasma exchange is the recommended approach for treating rapidly progressive bulbar weakness. In the disease management, oral steroids proved effective, plasma exchange produced marked, albeit short-term, improvement, while conventional immunosuppressants were comparatively less effective. Rituximab is a promising treatment for refractory MuSK-MG; in uncontrolled studies, nearly all treated patients achieved significant improvement with substantial decrease of medication. It is yet to be clarified whether the early use of rituximab could prevent the permanent bulbar weakness, which constitutes a relevant disability in these patients. [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]

Myasthenia gravis (MG) with antibodies against the muscle-specific tyrosine kinase (MuSK abs) is often a severe disease requiring aggressive treatment. Various immunosuppressive (IS) regimens have been employed; the efficacy of plasma exchange is unanimously recognized, while the indication for thymectomy is controversial. We evaluated the response to therapy in 57 MuSK-positive patients (12 M/45 F) comparing our experience with other authors' results. Disease severity and response to treatment were graded according to MG Foundation of America; follow-up ranged from 0.5–29 years. Owing to both MG severity and the unsatisfactory response to cholinesterase inhibitors, most patients (54/57) needed IS treatment, and 35 received one or more courses of plasma exchange and intravenous immunoglobulin. At the end of follow-up, the rate of complete remission was 8.8%, and IS treatment had been withdrawn in only 10/54 patients. The extent of therapeutic response varied considerably. With conventional IS therapy (prednisone alone or in combination with azathioprine or cyclosporine), most patients achieved good control of their disease, but 30% of them were left with permanent facial and bulbar weakness. In patients with refractory disease, the use of mycophenolate mofetil and rituximab proved very effective, as also reported by other authors. In our and others' experience, MuSK-positive MG markedly improves with IS therapy, although, in comparison with the AChR-positive disease, it is characterized by a lower remission rate, as a higher proportion of patients remain dependent on treatment. Thymectomy is mostly considered scarcely effective; however, at present, no firm conclusions can be drawn on its role in the treatment of this form of MG. [ABSTRACT FROM AUTHOR]