Co-occurrence of multiple sclerosis and myasthenia gravis in British Columbia.

We describe eight patients with associated multiple sclerosis (MS) and myasthenia gravis (MG). Patients were less than 50 years old at the time of onset, and seven were female. The clinical course of both MS and MG was mild in most patients. To our knowledge, this represents the largest reported series. We provide further evidence for a nonrandom association of these two diseases and discuss common mechanisms of pathogenesis.