EMG evidence of myopathy and the occurrence of titin autoantibodies in patients with myasthenia gravis

We studied 65 patients with myasthenia gravis (MG). Clinical, neurophysiological, immunological, and histological findings suggested the coexistence of a presumed autoimmune myopathy. The clinical features were persistent pyridostigmine-resistant weakness and atrophy of striated muscles. The myopathy was found more often in patients with late-onset MG than in those with early-onset (37% vs 13%). Patients with myopathy were also prone to have other immune disorders (47% vs 13%). Elevated titres of antibodies against titin were detected more often in patients with electromyography (EMG) evidence of myopathy than in the sera of those without, and only in late-onset MG cases.