Postinfectious myasthenia gravis: report of two children.

We report two children with transient myasthenia gravis preceded by viral illnesses. The first is a 5-year-old boy who developed oculobulbar weakness 2 weeks following a varicella-zoster infection. The second is a 4-year-old boy who developed facial diplegia and dysarthria several weeks following a viral pharyngitis. Myasthenia gravis was diagnosed based on the substantial decremental changes on 3 Hz repetitive motor nerve stimulation studies for the first child and on the positive edrophonium test and complete improvement in symptoms during pyridostigmine therapy for both children. In both cases, the symptoms gradually resolved and have not recurred following discontinuation of pyridostigmine. Molecular mimicry between the acetylcholine receptor and viral proteins might provide the nidus for the immune response in this variant of myasthenia gravis.