Progressive intellectual impairment in children with Encephalopathy related to Status Epilepticus during slow Sleep.

We investigated whether Encephalopathy related to Status Epilepticus during slow Sleep (ESES) in childhood was associated with progressive intellectual decline. Participants were identified from the caseload of a single paediatric neurosciences centre and EEG department. A retrospective review of overnight sleep EEG reports (n=2200) over a five-year period identified twenty-two children as having the neurophysiological characteristics of ESES. All had repeat neuropsychological assessment using the WISC-III (UK) and/or WPPSI-R (UK). There was a statistically significant reduction in Full-Scale IQ and Performance IQ across a mean and median time interval of two years. Around a third of the participants showed a clinically significant regression in intellectual functioning evidenced by =>12-point reduction in IQ. These patients were not distinguishable from the rest of the cohort in terms of clinical history, imaging or duration of ESES. The reduction in IQ reflected reduced processing speed, working memory and overall cognitive efficiency. Children with a history of ESES require close monitoring in order to support educational planning and provide families with accurate information about prognosis.