Acquired myasthenia gravis in childhood

This review discusses recent studies on myasthenia gravis with onset in childhood (juvenile myasthenia gravis) and neonatal myasthenia gravis.

The occurrence of myasthenia gravis in childhood is strongly influenced by genetic and environmental factors. Juvenile myasthenia gravis is associated with antibodies to the acetylcholine receptor (AChR) in most patients. Thymoma is rare, but often malignant in children. The frequency of juvenile myasthenia gravis with antibodies to the muscle-specific kinase (MuSK) varies markedly in different countries; some distinct features have been described. Management of juvenile myasthenia gravis does not differ, on the whole, from that of adult myasthenia gravis. Timing of thymectomy in young children is still controversial. Maternal antifetal type AChR antibodies can cause persistent focal weakness in the offspring, while neonatal myasthenia gravis associated with MuSK antibodies is often a severe and protracted albeit transient disease.

Juvenile myasthenia gravis, like its adult-onset counterpart, is a heterogeneous disease. Clinical presentation is influenced by antibody status, ethnicity and age of onset. Treatment is very effective, but guidelines and controlled trials are needed.The risk for neonatal myasthenia gravis appears to be markedly influenced by maternal antibody subclass and antigen specificity. Adequate treatment in mothers can reduce both frequency and severity of neonatal disease.