Seizures at presentation are predictors of relapsing disease in children presenting with acute disseminated encephalomyelitis (S35.004)

Objective: The objective of this study was to determine the frequency of seizures in both MOG-Ab positive and negative acute disseminated encephalomyelitis (ADEM) and evaluate if seizures at presentation are predictive of a relapsing disease course and post ADEM epilepsy. Background: Although initially thought to be a predominantly white matter disease, there is a growing report of both adult and children with myelin oligodendrocyte glycoprotein antibody (MOG-Ab) associated disease presenting with grey matter disease and seizures. Design/Methods: Children presenting with ADEM were identified from three tertiary paediatric neurology centres between 2005 and 2017 and case notes reviewed. MOG-Ab were tested as part of the clinical evaluation of children with demyelination. Results: 72 children were identified. MOG-Ab was positive in 48 (67%) of cases. 28 (39%) of those children went on to have a further neurological relapse. Relapses were more common in MOG-Ab positive children (26/48 vs 2/24; p=0.001). 15/72(20.8%) children had seizures during the acute presentation with ADEM. There was a trend towards more seizures at onset in the MOG-Ab positive group (13/48 vs 2/24; p=0.07). A diagnosis of post ADEM epilepsy was reported in 14/73(19.4%) and there was also a trend towards more ongoing seizures at last follow-up in the MOG-Ab positive group (12/48 vs 2/24; p=0.12). Seizure at onset were more frequent in the relapsing group than those with monophasic disease (10/28 vs 5/44; p=0.01); and ongoing seizures were more common in the relapsing group (9/28 vs 4/40; p=0.01). The odds ratio of relapsing disease with seizures at onset of first episode of demyelination was 4.3 (95% CI 1.3–14.5; p=0.02). Conclusions: MOG-Ab positivity was associated with a higher rate of relapse flowing ADEM. Seizures at first presentation is predictive of a relapsing disease course. These findings have both diagnostic and treatment implications. Disclosure: Dr. Rossor has nothing to disclose. Dr. Wright has nothing to disclose. Dr. Duignan has nothing to disclose. Dr. Ciccarelli has nothing to disclose. Dr. Das has nothing to disclose. Dr. Wassmer has nothing to disclose. Dr. Lim has nothing to disclose. Dr. Hemingway has nothing to disclose. Dr. Hacohen has nothing to disclose.