Abstracts

Rationale: ADEM has been considered a monophasic acute onset of encephalopathy and demyelination with characteristic MRI findings. Diagnostic dilemmas arose in cases that relapsed and didn’t fit either previously defined ADEM criteria, or the criteria for MS. This necessitated the recent development of additional ADEM classifications for relapsing subtypes; Multiphasic Disseminated Encephalomyelitis (MDEM) and Recurrent Disseminated Encephalomyelitis (RDEM), based on time to relapse, and consistent vs new lesion location. Our goal is to report our experience with seizures in children diagnosed with the new ADEM classifications: ADEM, RDEM, and MDEM. Methods: Medical records of children diagnosed with ADEM, RDEM, and MDEM, who were evaluated at the National Pediatric MS Center at Stony Brook from 2001 to 2008, were reviewed retrospectively. Results: Forty children (19 boys, 21 girls) from 16 different states were identified with a diagnosis of acute demyelinating encephalomyelitis. The mean age was 7 years (range: 1.5 to 15). Using the uniform classification of ADEM diagnoses developed by the International Pediatric MS Study Group, there were 22(55%) ADEM, 11(27.5%) MDEM, 6(5%) RDEM, and 1(2.5%) rediagnosed as neuromyelitis optica. Thirteen (32.5%) had one or more episodes of seizure. Seizure types were focal 4(31%), generalized 1(8%), status epilepticus 2(15%), and unknown or undocumented seizure type 6(46%). Nine of these children were treated for varying periods of time with one or more of the following antiepileptic drugs: levetiracetam 3, oxcarbazepine 4, carbamazepine 5, phenytoin 1, valproic acid 2, topiramate 1, and lamotrigine 1. The number of children with seizures, categorized by subtype was ADEM 5, MDEM 6, and RDEM 2. Of the 5 with ADEM, 2 had focal seizures, 1 had status epilepticus, and 2 had unknown seizure types. There were 6 with MDEM, 2 focal seizure, 1 generalized, 1 status epilepticus, and 2 unknown. The 2 with RDEM had unknown seizure types. Of the total cohort of 40 children, 27(67.5%) had complete resolution of lesions on MRI, 9(22.5%) had incomplete resolution and/or new lesions; repeat MRI results were unavailable in 4(10%). Five of the 27(18.5%) with lesion resolution also had seizure resolution, while 2/3(67%) with incomplete resolution and/or new lesions had seizure resolution, and 1/3(33%) continued to have seizures. Four children were considered to have intractable seizures, 3 had MDEM and 1 had ADEM. MRI findings in the 3 with MDEM was mixed, 1 had lesion resolution, 1 still had lesion burden, and information on 1 was unavailable. The 1 child with ADEM had resolved lesions. Conclusions: Overall seizure occurrence in our cohort was similar to previously reported studies, but further analysis considering the new classification of ADEM diagnoses has revealed that children with MDEM had a higher frequency of intractable seizures than those with ADEM or RDEM, regardless of lesion resolution. Analysis of ADEM subtypes may provide additional information on appropriate seizure treatment, prognosis, and features in ADEM that may predispose patients to epilepsy.