Spike-Wave Index Assessment and Electro-Clinical Correlation in Patients with Encephalopathy Associated with Epileptic State During Slow Sleep (ESES / CSWS); Single-Center Experience

•Status epilepticus during sleep (ESES/CSWS) syndrome is an epileptic encephalopathy affects the development and cognitive functioning of children.•ESES/CSWS, has a wide range of SWI, patients with SWI> 50% should also be followed up with neuropsychological evaluations.•Etiology seems to have the major impact on long-term neurocognitive outcome.•Age of onset, ESES duration, and spike-wave index also appears to be the main determinants of neurocognitive outcome. This study aimed to describe the electroclinical spectrum and neurocognitive outcome in children with epileptic encephalopathy with status epilepticus during sleep (ESES) according to the EEG patterns. Records of 48 (19 males, 29 females) patients with ESES/CSWS syndrome were retrospectively evaluated for data on sleep and awake EEGs, psychometric tests, and brain MRI. Patients with a spike-wave index (SWI) of at least 50 % in the NREM sleep EEG were included in the study. Electrophysiologic findings were separated into two groups based on SWI: SWI>85-100 % (typical ESES) and SWI