Myasthenic crisis

DEFINITION

Myasthenic crisis is a life-threatening condition, which is defined as weakness from acquired myasthenia gravis (MG) that is severe enough to necessitate intubation or to delay extubation following surgery [1]. The respiratory failure is due to weakness of respiratory muscles.

Severe bulbar (oropharyngeal) muscle weakness often accompanies the respiratory muscle weakness, or may be the predominant feature in some patients. When this results in upper airway obstruction or severe dysphagia with aspiration, intubation and mechanical ventilation are necessary.

This topic will review the evaluation and treatment of myasthenic crisis and rapidly worsening MG. Other aspects of MG are discussed separately. (See "Clinical manifestations of myasthenia gravis" and "Diagnosis of myasthenia gravis" and "Treatment of myasthenia gravis".)

PRECIPITANTS

Myasthenic crisis may be precipitated by a variety of factors, most often a concurrent infection. It can also follow a surgical intervention, pregnancy, childbirth, or tapering of immunosuppressive medications. In addition, myasthenic crisis can occur spontaneously as part of the natural history of myasthenia gravis (MG) itself. A number of drugs can increase the weakness in myasthenia (table 1) and should be considered as possible precipitants in this setting. This is of more concern with certain antibiotics (aminoglycosides, erythromycin and azithromycin), cardiac drugs (beta-blockers, procainamide, and quinidine), and magnesium.

A potential major side effect of excessive anticholinesterase medication is weakness, which can be difficult to distinguish from worsening MG. This paradoxical weakening with anticholinesterase medications is called "cholinergic crisis." However, cholinergic crisis is rarely if ever seen with dose limitation of pyridostigmine to less than 120 mg every three hours. Cholinergic crisis is so rare that it should not be the presumed cause of increasing weakness unless the doses taken are known to significantly exceed this range. Otherwise, even in the presence of cholinergic side effects, it should be assumed that the patient's underlying MG is worsening and appropriate treatment should be initiated.

             

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Literature review current through: Mar 2014. | This topic last updated: Dec 18, 2012.
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References
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  1. Bedlack RS, Sanders DB. On the concept of myasthenic crisis. J Clin Neuromuscul Dis 2002; 4:40.
  2. Juel VC. Myasthenia gravis: management of myasthenic crisis and perioperative care. Semin Neurol 2004; 24:75.
  3. Jani-Acsadi A, Lisak RP. Myasthenic crisis: guidelines for prevention and treatment. J Neurol Sci 2007; 261:127.
  4. Chaudhuri A, Behan PO. Myasthenic crisis. QJM 2009; 102:97.
  5. Mier A, Laroche C, Green M. Unsuspected myasthenia gravis presenting as respiratory failure. Thorax 1990; 45:422.
  6. Dushay KM, Zibrak JD, Jensen WA. Myasthenia gravis presenting as isolated respiratory failure. Chest 1990; 97:232.
  7. Rabinstein AA, Wijdicks EF. Warning signs of imminent respiratory failure in neurological patients. Semin Neurol 2003; 23:97.
  8. Bird, SJ, Teener, JW. Acute neuromuscular weakness. In: The Intensive Care Unit Manual, Lanken, PN, Hanson, CW, Manaker, S (Eds), W.B. Saunders, Philadelphia, 2001. p.755.
  9. Varelas PN, Chua HC, Natterman J, et al. Ventilatory care in myasthenia gravis crisis: assessing the baseline adverse event rate. Crit Care Med 2002; 30:2663.
  10. Clark WF, Rock GA, Buskard N, et al. Therapeutic plasma exchange: an update from the Canadian Apheresis Group. Ann Intern Med 1999; 131:453.
  11. Gajdos P, Chevret S, Clair B, et al. Clinical trial of plasma exchange and high-dose intravenous immunoglobulin in myasthenia gravis. Myasthenia Gravis Clinical Study Group. Ann Neurol 1997; 41:789.
  12. Qureshi AI, Choudhry MA, Akbar MS, et al. Plasma exchange versus intravenous immunoglobulin treatment in myasthenic crisis. Neurology 1999; 52:629.
  13. Gajdos P, Tranchant C, Clair B, et al. Treatment of myasthenia gravis exacerbation with intravenous immunoglobulin: a randomized double-blind clinical trial. Arch Neurol 2005; 62:1689.
  14. Gajdos P, Chevret S, Toyka KV. Intravenous immunoglobulin for myasthenia gravis. Cochrane Database Syst Rev 2012; 12:CD002277.
  15. Mandawat A, Kaminski HJ, Cutter G, et al. Comparative analysis of therapeutic options used for myasthenia gravis. Ann Neurol 2010; 68:797.
  16. Skeie GO, Apostolski S, Evoli A, et al. Guidelines for treatment of autoimmune neuromuscular transmission disorders. Eur J Neurol 2010; 17:893.
  17. Gilhus NE. Neuromuscular disease: acute treatment for myasthenia gravis. Nat Rev Neurol 2011; 7:132.
  18. Sathasivam S. Current and emerging treatments for the management of myasthenia gravis. Ther Clin Risk Manag 2011; 7:313.
  19. Sathasivam S. Evidence for use of intravenous immunoglobulin and plasma exchange in generalised mysasthenia gravis. Adv Clin Neurosci Rehabil 2009; 9:8.
  20. Seneviratne J, Mandrekar J, Wijdicks EF, Rabinstein AA. Predictors of extubation failure in myasthenic crisis. Arch Neurol 2008; 65:929.
  21. Alshekhlee A, Miles JD, Katirji B, et al. Incidence and mortality rates of myasthenia gravis and myasthenic crisis in US hospitals. Neurology 2009; 72:1548.
  22. Thomas CE, Mayer SA, Gungor Y, et al. Myasthenic crisis: clinical features, mortality, complications, and risk factors for prolonged intubation. Neurology 1997; 48:1253.