Juvenile myasthenia gravis with prepubertal onset

Juvenile myasthenia gravis (JMG) with prepubertal onset is an uncommon dise ase. We studied 19 patients with age at onset ranging from 1.5 to 9.2 years and compared their clinical characteristics and response to therapy with 1 14 cases with MG onset after the prepubertal age, up to 20 years. Neither s ex prevalence nor autoimmune diseases other than MG were found in younger p atients. Although ocular myasthenia was more frequent than in later-onset J MG, children with generalized symptoms were often severely affected and res piratory involvement was present in 8/19 patients. Anti-acetylcholine recep tor antibodies were detected at a lower rate and, in contrast with results in older patients, seronegativity was more frequent among children with gen eralized disease. Three out of six patients with onset before the age of fi ve showed spontaneous remission. Nine prepubertal patients underwent thymec tomy and, as most of them also received immunosuppressive therapy, the infl uence of surgery on disease outcome remains unclear; in no case was thymoma found. This is in contrast to the good results after thymectomy and the pr esence of thymoma in the later-onset group. Eleven patients in the prepuber tal series were treated with immunosuppressive therapy. At the end of follo w-up, most patients were in good condition. The frequency of immunosuppress ive therapy and the rate of good therapeutic results did not differ from th ose observed in older patients. (C) 1998 Elsevier Science B.V. All rights r eserved.