Children with Ocular MG Younger Than Those with Generalized MG and Respond Well to Treatment, Study Says

Children with ocular myasthenia gravis respond well to treatment, as largely do children with generalized myasthenia gravis, according to a single-site study that found no “significant differences” in response rates.

Still, half of its 22 ocular patients achieved remission, its researchers said. Children with ocular disease are also diagnosed at younger ages than those with generalized myasthenia gravis, reflecting the earlier onset of symptoms in ocular cases.

The study, “Response to Treatment in Pediatric Ocular Myasthenia Gravis,” was published in Muscle & Nerve.

In children, myasthenia gravis (MG) almost always appears in one of two forms: ocular myasthenia gravis (OMG), where weakness is evident only in the eyelids and surrounding tissue, whereas in generalized myasthenia gravis (GMG), various tissues throughout the body are affected.

For children with MG, studies detailing how these two disease types tend to differ in important clinical factors, like how patients respond to treatment, are lacking.

Researchers reviewed clinical data for children with MG who were seen at Children’s Health and Texas Scottish Rite Hospital, in Dallas, between 1990 and 2018. Of the 60 children included, 22 had OMG and 38 had GMG. Both groups had twice as many girls as boys, and the majority of children in both groups were either Hispanic or black, though there were proportionately more white children in the GMG group.

Researchers compared the children with OMG to those with GMG, looking for differences in terms of clinical factors and/or treatment outcomes. Treatment strategies themselves were similar in both groups, with most started on prednisone within a year of being diagnosed. Moreover, none of the OMG patients were taken off steroids due to side effects. No child was treated exclusively with Mestinon (pyridostigmine).

Two noteworthy differences were identified. First, children with OMG tended to be younger at disease onset than those with GMG; on average, age of onset was 4.14 years in the OMG group and 9.92 years in the GMG group. This difference was statistically significant.

Second, based on Millichamp and Dodge grades, children with OMG had better responses to treatment: 95.5% of children with OMG were classified as either grade A or B, as compared to 73.7% of children with GMG. (Grades closer to the start of the alphabet indicate a better treatment response in this classification system.)

This difference was not statistically significant: that is, mathematically, it is impossible to rule out the possibility that this difference was due to chance. The researchers believe that this lack of significance was probably attributable to the relatively small sample size; however, further studies will be needed to confirm this.

“In conclusion,” the researchers wrote, “our retrospective study of JMG [juvenile MG] showed that children with OMG present at younger ages compared to children with GMG” and “approximately half of those with OMG experienced remission with treatment.”