Abstracts

Rationale: Epilepsy with Myoclonic Atonic Seizures (EMAS), also known as Doose syndrome, has an incidence of 1 in 10,000 children, making up 1-2% of childhood epilepsy syndromes. Prior studies of EMAS cohorts suggest that tonic seizures and frequent generalized interictal discharges may be associated poorer outcomes. However, EMAS can be hard to distinguish from other epilepsy diagnosis such as Lennox-Gastaut Syndrome (LGS). The aim of the current study is to determine potential markers of intractable seizures and developmental outcomes in a cohort of potential EMAS patients regardless of final diagnosis. Methods: A retrospective chart review was performed at a single institution. Eligibility criteria included a faculty member suspecting a diagnosis of EMAS at any point in the patient’s course. EEG and seizure types were compared to developmental outcomes and seizure remittance to identify markers of a poor outcome. Associations were tested with Chi-square or fisher exact test. Details of genetic findings and phenotypes by diagnosis are discussed in other abstracts. Results: Seventy-seven patients were identified with a mean age at last visit of 7.25 years (SD 3.0) and 75% male (58/77). Final diagnosis included the following: EMAS (73%, n=56), LGS (10%, n=8), idiopathic generalized epilepsy (9%, n=7), and other (8%, n=6). Seizures remitted in 31 (40%) patients and remained refractory in 46 (60%). Sufficient developmental data was available for 70 patients of which 26% (18) had normal development. The following features were more likely in those with refractory seizures: tonic seizures (3/26, p=0.03), paroxysmal fast activity (17/21, p=0.02), diffuse slowing (34/48, p=0.01), interictal slow spike-wave discharges (23/28, p=0.002), and multifocal discharges (22/27, p=0.004). Patients with EEG findings of diffuse slowing (36/42, p=0.007) or multifocal spikes (23/24, p=0.003) at any point were more likely to have developmental delays, but not those with paroxysmal fast activity or slow spike and waves. Developmental delay was not associated with the presence of specific seizure types. A decrease in the posterior dominant rhythm from one EEG to the next (excluding those with a situational explanation like status epilepticus or recent benzodiazepine administration) was more likely in patients with abnormal developmental outcomes (21/23, p=0.04). However this was seen in less than half of all the patients with abnormal development. Conclusions: Clinical and electroencephalographic features are associated with refractoriness of seizures and developmental outcomes regardless of final diagnosis. A prospective study should confirm and refine these findings and determine the utility of these features as biomarkers for the most important outcomes. Funding: NIH NINDS K12 for the first author