Late onset forms of myasthenia gravis.: Comparison with early-onset myasthenia gravis.

Introduction. The incidence of myasthenia gravis appears to be increasing in elderly but few studies have been devoted to late onset myasthenia gravis. Patients and methods. We retrospectively compared myasthenic patients with an age at onset above or below 35 years which were observed in two departments of Neurology from 1980 to 2002. Results. 81 cases were included, 28 of which were late onset myasthenia gravis. The two populations were similar in terms of sex-ratio, clinical symptoms, course of the disease and therapeutic response. There was a trend for older patients to present more frequently at onset with dysphagia and axial or proximal involvement, and to have extra-ocular symptoms more quickly. Antibodies against acetylcholine receptor and striated muscle were statistically more frequent in elder patients. Conclusions. A late onset is not a factor of poor prognosis in myasthenia gravis and older patients must be treated in the same way than younger ones.