Electroclinical Predictors of Cognitive and Seizure Outcome in Children with Epileptic Encephalopathy Due to Electrical Status Epilepticus in Sleep (ESES)

Background: Epileptic encephalopathy (EE), associated with ESES, with its associated impact on cognition and language, is an important cause of morbidity in children. The effects of various treatment modalities and the factors affecting treatment response are not fully understood.

Methods: Case records of patients admitted in the institute and diagnosed to have EE with ESES pattern on EEG were accessed. Spike and wave index (SWI) was calculated from sleep records. Language development was assessed using Receptive-Expressive Emergent Language Scale and seizure outcome using the modified Engel seizure score.

Results: Fifty-two children with age ranging from 1 to 19 years were included (idiopathic ESES, n = 19 and symptomatic ESES with pre-existing developmental delay and/or structural brain lesions, n = 33). The two groups differed in terms of younger age at seizure onset in symptomatic ESES (p = 0.006), early age at language regression (p = 0.046), history of neonatal seizures (p = 0.038) and slowing of background on EEG (p = 0.024). Language regression was noted in 63.5% of the cohort. Twenty-five (48%) patients received steroids alone and showed improvement in seizure (p ≤ 0.001) and language outcomes at 1 year (p = 0.021), while 21 (40.3%) received steroids + IVIgG and showed improvement in seizure outcome (p = 0.002) at 1 year. On 1- year follow-up, seizure remission was noted in 13 (25%) patients with improvement in seizure score in 32/39 (82%) patients and language improvement in 60.8%. Patients with normal background on EEG (p = 0.03), generalized spikes (p = 0.05), no Fz negative spikes (p = 0.01), and SWI < 1.70 (p = 0.004) were found to have favorable cognitive outcomes on follow-up. 31/45 (68.9%) patients had persistent ESES at 1-year follow-up.

Conclusion: Despite clinical differences, idiopathic and symptomatic ESES have similar response to intervention. Addition of IVIgG to steroids improve seizure outcome, but may not have an impact on cognitive outcome, which is determined by EEG variables.