Treatment

Cases of suspected myasthenia gravis should be referred to a neurologist for confirmation of diagnosis and supervision of treatment (1).

The treatment of myasthenia gravis involves:

• oral anticholinesterase medication, e.g. pyridostigmine or neostigmine, results in symptomatic improvement in most cases. They are of greatest benefit in patients with mild symptoms, often completely correcting weakness in these cases and improving strength in those moderately affected. The common side effect of this treatment is diarrhoea and this can be treated by dosage modification or propanthalene
  
  
• if there is life-threatening or respiratory weakness developing in treated patients, then this usually requires immediate control of the airway, treatment of any underlying infection, and a course of plasma exchange; increasing the anticholinesterase dose at this stage is of little help, and it increases airway secretions
  
  
• thymectomy - required if there is a thymoma because of the risk of local infiltration. Also occasionally undertaken in other non-thymoma patients with myasthenia (2)
  • in the UK the usual practice is to perform a thymectomy in patients who are under the age of 40 years at the time of diagnosis, with generalised myasthenia gravis and raised anti-AChR antibodies titre
    
    
• immunosuppression with corticosteroids +/- cytotoxic agents is also highly effective in inducing remission of disease and may be necessary preliminary to surgery in patients with severe disease. In myasthenia, steroids are introduced at a low dose which is then increased. This slow introduction of steroids prevents the worsening of symptoms that occurs if high doses are given too quickly. Once the disease is controlled, steroids are reduced gradually (3)
  
  
• plasma exchange (3)
• intravenous immunogobulin (IVIg) or plasmapheresis can be used in severe disease and exacerbations (4)
  • plasmapheresis is probably better for true myasthenic crises
    • plasmapheresis may produce a more rapid response, but IVIg is less expensive and may have fewer complications.
• rituximab may prove beneficial in patients with myasthenia gravis resistant to immunosuppressive therapy and patients with MuSK antibodies (5)
• thymectomy is beneficial for non-thymomatous myasthenia gravis, and newer, less-invasive techniques show comparable efficacy, with shorter hospital stays

Reference:

1. Melzer N et al. Clinical features, pathogenesis, and treatment of myasthenia gravis: a supplement to the Guidelines of the German Neurological Society. J Neurol. 2016 Aug;263(8):1473-94
2. Gronseth GS, Barohn R, Narayanaswami P. Practice advisory: thymectomy for myasthenia gravis (practice parameter update). Report of the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology. Neurology. 2020 Apr 21;94(16):705-9.
3. Sanders DB, Wolfe GI, Benatar M, et al. International consensus guidance for management of myasthenia gravis: executive summary. Neurology. 2016 Jul 26;87(4):419-25.
4. Gajdos P, Chevret S, Toyka KV. Intravenous immunoglobulin for myasthenia gravis. Cochrane Database Syst Rev. 2012;(12):CD002277.
5. Tandan R, Hehir MK 2nd, Waheed W, et al. Rituximab treatment of myasthenia gravis: a systematic review. Muscle Nerve. 2017 Aug;56(2):185-96.