Long-term outcome and tolerability of the ketogenic diet in drug-resistant childhood epilepsy--the Austrian experience

Purpose: To evaluate the long-term efficacy/tolerability of the ketogenic diet (KD) in paediatric drug-resistant epilepsies.

Methods: Data from children who were treated between 1999 and 2008 and had continuous follow-up of at least 6 months after initiation of the KD were analysed retrospectively. Response was defined as > or = 50% seizure reduction. Treatment effects on EEG, developmental outcome and the "outcome-predictive" value of various clinical factors were also assessed.

Results: 50 children (22 boys; mean age 4.5 years+/-3.55) were included. Mean follow-up was 3.93+/-2.95. 50% of the patients were responders, 48% of them became seizure free. 50% were non-responders, 20% of them deteriorated. In responders, EEG background activity improved significantly (p=0.014) and a significantly lower rate of epileptic discharges (p=0.009) was seen after 6 months. In addition, neurological examination findings demonstrated significant developmental progress (p=0.038). Favourable treatment outcome was associated with a shorter disease duration (p=0.025) and generalised tonic clonic seizures (p=0.059). No further significant outcome predictors were detected. However, response was 44% in patients with infantile spasms, 62.5% in those with Dravet syndrome and 50% in Lennox-Gastaut-syndrome. Side effects occurred in 28%, but discontinuation of the KD was not required in any case. They most often observed with concomitant topiramate (p=0.001) and valproate (p=0.046).

Conclusion: Despite the retrospective nature of the study and the inhomogeneous patient sample, we found good long-term effects of the KD on seizure frequency, EEG and neurological development.