Occurrence of CNS demyelinating disease in patients with myasthenia gravis.

An increased incidence of multiple sclerosis (MS) has been reported in patients with myasthenia gravis (MG). We reviewed records of 214 patients with MG. CNS demyelinating disease (CNSDD) occurred in five patients (2.3%). CNSDD always occurred after the diagnosis of MG. Myelitis (including recurrent myelitis) was the most common CNS manifestation. All patients had antinuclear antibodies. CNSDD occurs more frequently in patients with MG and may be related to immune-modulating treatments including thymectomy.