We report our experience with single-fiber electromyography (SF-EMG), acetylcholine receptor antibody assays, and Lancaster Red-Green tests of ocular motility with edrophonium chloride in the diagnosis of myasthenia gravis (MG). Over a period of almost 3 years, 43 patients in whom repetitive-stimulation nerve conduction tests were nondiagnostic had SF-EMG studies; 34 (79%) were positive. Examination of more proximal muscles yielded a higher likelihood of positive results. Anti-acetylcholine receptor antibodies were detected in 25 (71%) of 35 patients whose sera were assayed, and Lancaster Red-Green tests of ocular motility were positive in 13 (81%) of 16 patients studied. No single test was superior in diagnosing MG, but the three were complementary. If the patients with mild MG are tested by all three methods, at least 95% should have laboratory confirmation of MG.
ASJC Scopus subject areas