Antibodies against muscle-specific kinase in juvenile myasthenia gravis

Management of juvenile myasthenia gravis

Juvenile myasthenia gravis is an uncommon autoimmune disorder. Its management is not standardized. Juvenile myasthenia gravis is pathophysiologically similar to myasthenia gravis in adults. However, a number of significant particularities related to race, age at onset, severity, and antibody status complicate the management. We summarize the unique clinical features of juvenile myasthenia gravis and review the therapeutic options.

Long remission in muscle-specific kinase antibody-positive juvenile myasthenia

The clinical course of anti-muscle specific kinase-positive myasthenia in children has been little reported. Described here is the case of an 8 year-old boy who presented with ptosis and generalized weakness, which resolved within 1 month without any immunomodulatory treatment. This spontaneous remission lasted 6 years and was then followed by a relapse with bulbar symptoms. The patient was put on plasmapheresis; after initial benefit, symptoms worsened and serum antibody levels persisted. This case constitutes an example of the variability of the clinical presentation, course, and therapeutic response in anti-muscle specific kinase-positive myasthenia in childhood.

Serological follow-up in juvenile myasthenia: clinical and acetylcholine receptor antibody status of patients followed for at least 2 years

Thirty cases of juvenile myasthenia with at least 2 years' follow-up and one measurement of acetylcholine receptor antibody titer were evaluated. Symptoms were initially ocular in 15 (50%) cases; only one developed generalized disease and others remained ocular in 2-24 years' follow-up. Antibodies to acetylcholine receptor (AchRAb) were absent in 12/30 (40%) of all patients initially, but became positive in 5/28 (18%) on further testing in 1-5 years. Spontaneous remission was observed in 6 cases (20%) of whom one became seropositive, and late relapses after 5-11 years' remission were observed in 3 patients with ocular myasthenia, of whom only one developed AchRAbs. Our results show ocular JM has an exceptional tendency to remain confined to these muscles, and delaying the classification of the disease as AchRAb-negative for a few years and repeating serological tests is advisable in the follow-up.