Incidence and Clinical Features of Pediatric Myasthenia Gravis
Erick D. Bothun, MD; Sasha A. Mansukhani, MBBS, MS, FICO; David O. Hodge; Nancy N. Diehl; Brian G. Mohney, MD
Introduction: The purpose of this study was to describe the incidence and clinical characteristics of pediatric myasthenia gravis.
Methods: The medical records of all children < 19 years in Olmsted County, Minnesota diagnosed with any form of myasthenia gravis from January 1, 1966, through December 31, 2015, were retrospectively reviewed.
Results: Six of the 364 children were residents of Olmsted County at the time of their diagnosis, yielding an annual age- and sex-adjusted incidence of 0.35 per 100,000 patients, or 1 in 285,714 patients younger than 19 years. The incidence of juvenile myasthenia gravis (JMG) and congenital myasthenia syndrome (CMS) was 0.12 & 0.23 per 100,000 respectively. Of the 364 study children, 217 (59.6%) had JMG, 141 (38.7%) had CMS, and 6 (1.7%) had Lambert-Eaton syndrome, diagnosed at a median age of 13 (N=210), 5 (N=137), and 12 respectively. A majority of the JMG and CMS patients had ocular involvement (90.3 and 85.1% respectively), including ptosis and ocular movement deficits. The median follow-up time was 3.5 years (range, 0 days to 50.5 years (N=351)); complete remission was reported in 42/133 (31.6%) of children with JMG and none of 89 children with CMS with follow up more than a year.
Discussion: There are no known prior studies on the incidence of CMS nor of JMG in the United States, and reports of childhood Lambert-Eaton syndrome are rare. (1-3)
Conclusion: Although relatively rare, myasthenia gravis in children has two predominant forms, CMS and JMG, both of which commonly have ocular involvement.
References: 1. Popperud TH, Boldingh MI, Brunborg C, Faiz KW, Heldal AT, Maniaol AH, et al. Juvenile myasthenia gravis in Norway: A nationwide epidemiological study. Eur J Paediatr Neurol. 2017;21(2):312-7.
2. McMacken G, Abicht A, Evangelista T, Spendiff S, LochmÃ¼ller H. The Increasing Genetic and Phenotypical Diversity of Congenital Myasthenic Syndromes. Neuropediatrics. 15.05.2017. 2017;48(4):294-308.
3. VanderPluym J, Vajsar J, Jacob FD, Mah JK, Grenier D, Kolski H. Clinical characteristics of pediatric myasthenia: a surveillance study. Pediatrics. 2013 Oct;132(4):e939-44