Incidence and Ocular Features of Pediatric Myasthenias

Abstract

Purpose: To report the incidence, demographics, and ocular findings of children with myasthenia.

Design: Retrospective cohort study.

Methods: The medical records of all children (<19 years) examined at Mayo Clinic with any form of myasthenia from January 1 1966, through December 31, 2015, were retrospectively reviewed.

Results: A total of 364 children were evaluated during the study period, of which 6 children were residents of the Olmsted County at the time of their diagnosis, yielding an annual age- and sex-adjusted incidence of 0.35 per 100 000 <19 years, or 1 in 285 714 <19 years. The incidence of juvenile myasthenia gravis (JMG) and congenital myasthenic syndrome (CMS) was 0.12 and 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 13.5, 5.1, and 12.6 years, respectively. A majority of the JMG and CMS patients had ocular involvement (90.3% and 85.1%, respectively), including ptosis and ocular movement deficits. Among children with at least 1 year of follow-up (JMG; median, 7.1 years, CMS; median, 7.0 years), improvement was seen in 88.8% of JMG patients (complete remission in 31.3%) and in 58.3% of CMS patients.

Conclusion: Although relatively rare, myasthenia gravis in children has 2 predominant forms, CMS and JMG, both of which commonly have ocular involvement. Improvement is more likely in children with the juvenile form.

Figure 1.

Age at diagnosis for 217 children with JMG & 141 children with CMS from 1966 through 2015 at Mayo Clinic

Figure 2.

Outcomes for 134 children with juvenile myasthenia gravis & 96 children with congenital myasthenic syndrome followed for at least 1 year from 1966 through 2015 at Mayo Clinic