Myasthenia gravis in childhood.

Clinical features, serum acetylcholine receptor antibody (AChRAb) titres and course were reviewed in a series of 25 congenital (CMG) and 30 juvenile (JMG) myasthenia gravis cases to recognize characteristics of childhood-onset myasthenia and its subgroups. The initial symptom for CMG is ptosis accompanied or followed by generalized weakness; myasthenic crises do not occur and spontaneous remissions are rare. In JMG, the distribution of weakness remains the same, but the severity fluctuates: spontaneous remissions (6 patients) and myasthenic crises (10 patients) are observed. Good response to anticholinesterase drugs is slightly more frequent in JMG (62 versus 41%). AChRAbs were present in 9/26 JMG tested, girls with onset after 11 years being more likely to be Ab-positive. Since patients with autoimmune myasthenia and a young age of onset are often seronegative, clinical features such as changing distribution of weakness, fluctuating severity, or response to treatment might be considered as supportive criteria for differentiating JMG from CMG.