Childhood myasthenia gravis: clinical features and outcomes.

OBJECTIVE: To study the clinical features, treatment, outcome and factors that affected the outcome of myasthenia gravis (MG) in children.

MATERIAL AND METHOD: Children aged 16 years or less with diagnosed myasthenia gravis (MG) seen at Queen Sirikit National Institute of Child Health over a 15-year period with a minimum follow-up of 6 months were reviewed. Demographic, clinical characteristics, treatment and the outcome were analyzed.

RESULTS: One hundred and nineteen MG patients, 100 patients (84%) were ocular MG (OMG) and 19 patients (16%) were generalized MG (GMG). Median age of onset was 4.1 years. OMG patients had the age of onset earlier than GMG patients (p = 0.01). Female to male ratio was 1.8: 1. Ptosis was a clinical feature in 99%, accompanied with ophthalmoplegia in 63%, diplopia in 19.3%, extremity weakness in 13.4%, respiratory muscle weakness in 9%, head tilt in 10.1%, dysphagia in 7.5%, hyperthyroidism in 3.4% and epilepsy in 2.5%. One hundred and six patients who had ptosis as the initial symptom 67% were bilateral ptosis, 33% were unilateral ptosis, 10 patients progressed to GMG in 2 years. Almost all patients were treated with pyridostigmine and prednisolone. At the end of follow-up, 60.5% had pharmacological remission for more than 3 months, 18.5% had complete remission without medication. No definite factors associated with the remission were identified.

CONCLUSION: OMG is the majority of MG patients and the age of onset is earlier than GMG. Early treatment by prednisolone may have the favorable effect on OMG in the progression to GMG and subsequent involvement to the other eye.