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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Answer

Answer

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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