Chloroquine myopathy and myasthenia-like syndrome

A young woman on chronic corticosteroid treatment for systemic lupus erythematosus developed a myasthenia-like syndrome 7 weeks after starting chloroquine therapy. Discontinuation of chloroquine allowed symptomatic and immunological remission within 6 months. Ocular symptoms reappeared following a second short course of chloroquine. A motor-point biopsy revealed a vacuolar myopathy with membranous bodies in intramuscular nerves. We discuss the possible role of chloroquine in the pathogenesis of a myasthenia-like syndrome.