Early Electroencephalographic Changes After Ketogenic Diet Initiation Are Associated With Clinical Response in...

Ketogenic diet (KD) is an established treatment option for pediatric drug-resistant epilepsy; however, early indicators of treatment response are limited. This study aimed to explore whether early changes in routine electroencephalographic (EEG) findings, particularly the interictal epileptiform discharge index (IED index), are associated with subsequent clinical response to KD therapy.

We conducted a single-center retrospective cohort study including children with drug-resistant epilepsy who initiated a classical ketogenic diet. Standardized natural sleep EEG recordings were obtained at baseline and approximately one month after diet initiation. IED ındex was calculated during the first five minutes of non-rapid eye movement sleep, and background activity was visually assessed using a standardized grading scale. Clinical response was defined as a ≥50% reduction in seizure frequency or seizure freedom at six months. EEG changes were compared between responders and non-responders, and receiver operating characteristic analysis was performed to evaluate the association between early EEG changes and clinical outcome.

Thirty-four patients were included, of whom 23 (67.6%) were classified as responders at six months. Baseline EEG characteristics did not differ between responders and non-responders. At one month, responders showed a significant reduction in IED index, whereas no significant change was observed in non-responders. A reduction in IED index of approximately 40% was associated with clinical response, demonstrating good discriminative performance. Changes in background EEG activity were observed in both groups and were not associated with seizure outcome.

Early reduction in IED index on routine sleep EEG is associated with favorable clinical response to the ketogenic diet. Routine EEG assessment may offer supportive electrophysiological information during early follow-up of KD therapy in pediatric drug-resistant epilepsy.