The ketogenic diet is effective in some types of drug-resistant epilepsy in childhood and should be offered early to help prevent deterioration of symptoms and psychomotor development, European researchers say.

In a prospective study, researchers at Vienna University assessed the effect of the ketogenic diet in a cohort of 183 children with drug-resistant epilepsy, with a focus on how responses varied according to the new 2017 International League Against Epilepsy (ILAE) classification of aetiology.

There was no difference in outcomes in terms of frequency of patients achieving seizure freedom with the ketogenic diet at  three months, but there were significant difference between aetiology groups in both seizure freedom and seizure reduction >50% at six and 12 months.

In patients with known aetiology, seizure freedom and seizure reduction >50% was most frequent at three months and then gradually declined at six and 12months. In contrast, in patients with unknown aetiology, seizure freedom was least frequent at three months, but increased at six months and then stabilized both at 12 months and at  last follow up.

Seizure freedom was significantly less frequent in the 129 patients epilepsy of known aetiology at six months (26% vs 43%) and beyond (22% vs 37%) compared to the 70 patients with epilepsy of unknown aetiology.

The independent determinants associated with positive outcomes included duration of epilepsy, number of previous antiseizure medications (ASMs), and age- appropriate psychomotor development.

Among patients with known aetiology the effectiveness of ketogenic diet was best for genetic (30% seizure freedom at last follow up) and structural aetiology (19%) and poorest for metabolic aetiology (8% at last follow up) epilepsy.

There were no differences  between groups in type and frequency of adverse effects.

The study investigators said the results could provide clinicians with a better understanding of  the effectiveness of the ketogenic diet and the prognosis in different groups of drug resistant epilepsy of known and unknown aetiologies.

Considering  the poor success of conventional anti-seizure medicines and early drug resistance in epileptic encephalopathies,  the early use  of  corticosteroids and the ketogenic diet could be  recommended in  specific conditions, they said. This would follow the  precision medicine model, with individuals with genetic and other epilepsies treated with therapies targeted specifically to their individual aetiology, they added.

The findings also provided further evidence that the ketogenic diet should be started as early as possible, before any deterioration of psychomotor development, to be the most effective, the researchers wrote in Epilepsia.

“We conclude that the ketogenic diet should be offered earlier to infants diagnosed with genetic epilepsy, even before drug resistance has developed. Moreover, consequent diagnostic workup and genetic testing to identify aetiologies  that respond best to the KD are useful for targeted therapy from the start.”