LOMG – Late-Onset Myasthenia Gravis


Late-Onset Myasthenia Gravis – A Changing Scene

Arch Neurol. 1999;56(1):25-27. doi:10.1001/archneur.56.1.25


The prevalence of myasthenia gravis (MG) among middle-aged and older patients has increased. Patients with early-onset MG live longer than before, but there is also an increase in late-onset MG (onset of the disease after the age of 50 years in patients with no clinical or paraclinical evidence of a thymoma). Epidemiological data support using the age of 50 years to separate early- and late-onset MG. The main immunological difference between early- and late-onset MG is the presence of antibodies to muscle titin, which are detected in approximately 50% of patients with late-onset MG. Treatment of late-onset MG has to be tailored both to the age of the patient and to the immunological findings of that particular form of MG.

The disease occurs, for the most part, in the third decade, and is rare before the age of 15, or after 70. In approximately 60 per cent of the patients the disease develops between the ages of 20 and 40.1

The concept that myasthenia gravis (MG) mainly affects young adults and is uncommon after the age of 50 years was based on clinical experience and supported by epidemiological data. In 1900, when Campbell and Bramwell2 surveyed the literature and added 1 case of their own, they identified 60 cases, 3 of which involved patients who were older than 50 years at the onset of their disease. By 1953, Schwab and Leland3 reported that 62% of women and 27% of men with MG were younger than 30 years at the onset of the disease. The corresponding figures reported by Simpson et al4 in 1966 were 49% women and 23% men. In both studies, the disease was uncommon among younger men, with the majority of male patients being older than 60 years. Men with MG formed 2 groups: one with the peak age at onset between 25 and 35 years and the other between 60 and 70 years.4 These observations were reflected in standard textbooks of neurology.

Today, some 40 years later, the onset of MG occurring after the age of 50 years is not uncommon. Recent studies have shown an increased prevalence of the disease among middle-aged and older patients.58 This may be the result of both an improved prognosis and a more advanced medical diagnosis among elderly patients. Certainly, most patients with MG receive better treatment today and have a longer life span than ever before. (YES, THEY DO. MDW)

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