What is the prevalence of myasthenia gravis?

Updated: Sep 20, 2018
  • Author: William D Goldenberg, MD; Chief Editor: Andrew K Chang, MD, MS  more...
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The estimated prevalence of myasthenia gravis is approximately 20 cases per 100,000 population, with the disease affecting twice as many women as men. The overall prevalence is approximately 150-200 per million. [2] However, in older age groups, men are affected more often and the disease is often misdiagnosed. [3] As a result, there is a bimodal distribution with a female predominance in the 2nd to 3rd decade of life and male predominance in the 6th to 8th decades. [1, 3, 2] Ocular complaints are more common in the first year and are the presenting symptom in 50% of cases. Often within 1 year, patients have generalized symptoms such as weakness or fatigue and one third of patients develop respiratory weakness, requiring mechanical ventilation. [4] Myasthenic crisis occurs in about 20% of patients with generalized myasthenia gravis. [3] Over the years, due to changes in treatment, prognosis and mortality havechanged. Mortality in the last 4 decades has seen a dramatic decrease from 75% to 4.5%. [2]

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