Electrophysiological, neurocognitive, and GFAP biomarker responses to corticosteroid therapy in children with ESES/CSWS

Developmental and/or epileptic encephalopathy with spike–wave activation during sleep (DE SWAS), including electrical status epilepticus during sleep (ESES/CSWS), is associated with seizures, neurocognitive regression, and characteristic electroencephalographic abnormalities. This study aimed to evaluate the clinical, electrophysiological, neurocognitive, and molecular response to corticosteroid therapy in children diagnosed with DE-SWAS, with a particular focus on serum glial fibrillary acidic protein (GFAP) as a potential biomarker of treatment response. Eleven children aged 6–12 years were retrospectively evaluated using clinical records, sleep electroencephalography with quantification of the spike–wave index (SWI), standardized neuropsychological test results, and serum GFAP measurements obtained before and after corticosteroid treatment. Neurocognitive assessment included the Wechsler Intelligence Scale for Children–Revised (WISC-R), Stroop Color and Word Test, Bender Visual–Motor Gestalt Test, and Turkish Receptive and Expressive Language Test (TIFALDI)High-dose intravenous methylprednisolone was administered monthly for six months. During follow-up, four patients became seizure-free, while the remaining seven demonstrated a reduction in seizure frequency and duration exceeding 50%. Complete normalization of electroencephalographic findings was observed in four patients, and a ≥ 50% reduction in SWI was observed in the remaining seven. Post-treatment neurocognitive evaluations demonstrated overall improvement, particularly in attention, executive functions, and receptive language domains. Mean serum GFAP levels decreased significantly following corticosteroid therapy (p = .017). These findings suggest that corticosteroid therapy is associated with favorable clinical, electrophysiological, and neurocognitive outcomes in children with DE-SWAS and that GFAP may represent a promising biomarker of disease activity and therapeutic response. Larger prospective studies are warranted to validate these results.