Myasthenia gravis in an 22 months-old girl – impressing improvement due to early adaequate therapy

Aims: Infantile Myasthenia gravis (MG) is a rare autoimmune disease, antibodies against the nicotinic acetylcholine receptor (AChR) can be found in 50% off all cases. Others as antibodies to muscle-specific kinase (MuSK) are less frequent. The prevalence of MG in infants below 1 year of age is approximately 1.1/106. If antibodies are missing, a congenital myasthenic syndrome (CMS) has to be taken into account. Therapeutical options are the treatment with acetylcholinesterase inhibitors and often also immunosuppression. Depending on clinical severity a plasmapheresis or intravenous immunoglobulin could be indicated. A thymectomy could increase the probability of remission.

Methods: We report on a 22-months-old girl with an uneventful neurological development. At the age of 20 months she showed a one-sided ptosis, in further course of both sides with a significant strength reduction in a context of a febrile common cold. First examinations without abnormal results in brain-MRI or blood. No elevation of AChR-antibodies at the beginning. Because of the typical clinical symptoms a therapy with pyridostigmine was started with only mild improvement. A few weeks later slightly elevated temperature due to a common cold, markedly reduced strength, serious ptosis, cough insufficiency; unable to sit, stand or walk. A slightly elevated AChR-antibodies-level was found (0.83 nmol/l), the repetitive nerve stimulation showed a decrement more than 10%.

Results: In addition to the treatment with pyridostigmine (5mg/kgBW/day) we started a therapy with steroids and thereafter also with azathioprine. An impressing improvement could be demonstrated even after reduction of steroids. The girl actually shows a stable status.

Conclusion: There are only few reports on infantile and juvenile MG patients and their therapy, evidence based recommendations for medical treatment do not exist. However a consequent drug therapy with acetylcholinesterase inhibitors, steroids and azathioprine reached a dramatic improvement in our patient and held it until now. Depending on clinical course and age a thymectomy have to be considered.

Myasthenia gravis childhood - pyridostigmin - steroids - azathioprine