Juvenile form of myasthenia gravis presenting as recurrent pulmonary infection with atelectasis.

Myasthenia gravis (MG), a chronic disease characterized by unusual fatigability of voluntary muscles, was first described by Willis. Three forms of MG are seen in childhood: juvenile MG, congenital MG and transient neonatal MG. Aside from age of onset, there is no difference in terms of pathology and pathogenesis between juvenile MG and adult-onset MG. Juvenile MG, like adult MG, appears to result from T-cell-initiated antibodies directed against end-plate Ach receptor protein. The onset of juvenile myasthenia can be insidious, although at times it is rapid, often a sequel to an acute febrile illness. Generally, muscles innervated by the cranial nerves are affected first, with bilateral ptosis being the most common presenting sign. Generalized weakness and dysphagia are less common presenting symptoms, while the clinical course is highly variable.