Myasthenia gravis in children: analysis of 18 patients

Abstract

-Myasthenia gravis (MG) in childhood is rare comprising 10 to 20 % of all myasthenic patients. We studied 18 patients with MG whose first symptoms started from 1 to 12 years of age, followed at the Department of Neurology of the UNI.ESP-EPM, from January 1983 to August 1997. There were 10 girls and 8 boys (1.2:1). Eleven patients (61%) presented moderate or severe generalized disease and 4 (22%) had at least one myasthenic crisis. EMG with supramaximal repetitive nerve stimulation was diagnostic in 8 (47%) out of 17 patients, and chest CT was normal in 14 patients. Seropositivity to acetylcholine receptor antibodies was found in 81.6% (9 out of 11 tested) and the levels had no relation to clinical severity. Nine out of 16 patients (56%) worsened with pyridostigmine alone and were treated with prednisone. .our out of those nine continued worsening despite steroids and were subjected to thymectomy (all showed thymic lymphoid follicular hyperplasia). Three patients (75%) improved markedly after thymectomy and one (25%) worsened, eventually getting better with intravenous immunoglobulin and oral azathioprine. MG treatment, using all resources available, has to be individualized for each child.KEY WORDS: myasthenia gravis, child. Miastenia gravis na infância: estudo de 18 pacientesRESUMO -A miastenia gravis (MG) em crianças é rara e perfaz 10 a 20% dos pacientes com a doença. Relatamos 18 pacientes cujo início dos sintomas ocorreu até os 12 anos de idade, acompanhados na Disciplina de Neurologia da UNI.ESP-EPM de janeiro de 1983 a agosto de 1997. Eram 10 meninas e 8 meninos (1,2:1,0). Doença generalizada moderada ou grave ocorreu em 11 crianças (61%) e 4 (22%) tiveram pelo menos uma crise miastênica. A eletroneuromiografia com estimulação repetitiva foi diagnóstica em 8 (47%) de 17 pacientes e a tomografia computadorizada do tórax não demonstrou aumento do timo em 14 pacientes. A positividade para o anticorpo anti-receptor da acetilcolina foi de 81,6% nos 11 pacientes testados e seu nível não se correlacionou com a gravidade dos sintomas. Nove dos 16 pacientes (56%) acompanhados apresentou evolução com piora tendo sido utilizada prednisona e 4 destes (25%) pioraram apesar desta terapia e foram submetidos a timectomia. Das quatro pacientes timectomizadas (todas com hiperplasia folicular linfóide do timo), 3 (75%) melhoraram e uma (25%) continuou piorando tendo sido medicada com imunoglobulina endovenosa e azatioprina. O tratamento da MG deve ser individualizado para cada criança para chegar-se o mais próximo de uma atividade de vida diária plena.

Myasthenia gravis in Ceará, Brazil: clinical and epidemiological aspects

“…Two patients had ocular myasthenia and three the generalized form of the disease. As for disease severity in early childhood, this finding is similar to data from Evoli et al and Morita et al who found not only a high frequency of ocular myasthenia but also an even higher incidence of severe disease with respiratory involvement 13,14 .…”

“…All patients in the group with such early age of onset in the present study were females. Such finding reflects that of a previous analysis of 18 patients under 12 years old, where there was a female predominance in pre-pubertal patients 14 , but another study failed to show differences in gender distribution in prepubertal MG 13 . Two patients had ocular myasthenia and three the generalized form of the disease.…”

“…The disease has a higher prevalence in women than in men, with an approximate female-to-male ratio of 2:1 12 . MG in childhood and adolescence is rare 13,14 . Girls are more frequently affected than boys in a proportion of 1.3:1 at pre-pubertal ages and 1.8:1 in peripubertal ages 15 .…”

“…In Brazil, there are relatively limited data on the occurrence of MG and its clinical and epidemiological aspects (Table 1) 5, 14,16 . There have been no reported studies of MG in Northeast Brazil.…”

Juvenile myasthenia gravis

“…Girls are more commonly affected than boys (1.3 -1.8) 4,5 . In Morita et al, Most of the cases presented between 9 to 12 years of age 6 . Our case was also a female child presented in the early age.…”