Abstracts

Rationale: The ketogenic diet (KD) is a medical treatment for children with intractable epilepsy. Independent of seizure reduction, children treated with the KD demonstrate improved developmental quotients, attention and social functioning. The relationship between interictal EEG abnormalities and cognitive functioning in children on the KD has not been well explored. The objective of this study is to examine the effects of the KD on the interictal EEG of children with intractable epilepsy. Methods: A retrospective analysis of EEG background activity obtained prior to and during KD treatment in 13 children was performed using Fast Fourier Transform (FFT). Interictal epileptiform discharges (IED) were quantified using computerized analysis, expressed as IED per minute. Sleep features were assessed. Clinical data on seizure frequency and severity, attention and behaviour were compared. Results: Overall, EEG tracings demonstrated a reduction in IED in 7 children and increased in 6 children. FFT revealed an increase in background activity frequency in 8 patients and a decrease in 5 patients. We identified a subgroup of patients who clinically became seizure free on KD, in whom a significant improvement in background activity and reduction in IED (80% of children) was noted. All patients reported improvement in degree of alertness and some progress in developmental and/or cognitive function regardless of EEG findings while on KD. Conclusions: Changes in interictal EEG may result in clinical improvements beyond seizure reduction in children treated with KD. In a subgroup of children clinical seizure freedom on KD was correlated with significant improvement in background activity and reduction in IED was noted.