DO THE BENEFITS OF THE KETOGENIC DIET LAST?
A ketogenic diet of high fat, low carbohydrate and adequate protein has been used in the treatment of childhood epilepsy for almost 100 years. It is usually prescribed when at least two decent trials of anti-epileptic drugs (AEDs) have failed to control a child’s seizures, although it is only suitable in a proportion of cases. Children normally continue to take AEDs whilst following the diet, but if they respond to it (i.e. their seizures become controlled), the drug doses can often be reduced. A small number are able to come off their AEDs completely.
There has been little research into the sustainability of the ketogenic diet, but scientists in Pennsylvania have now tried to address this. In a recent project they investigated the risk of seizure recurrence in children who had achieved at least one month of seizure freedom, within two years of following the ketogenic diet. They also tried to find out if there were any clinical features about a child’s epilepsy that were linked with a lower risk of seizure recurrence. If this were the case, it would help doctors to predict the children who were likely to benefit from the diet in the future.
During the study the researchers reviewed the medical records of 276 children with epilepsy, who were initiated on the ketogenic diet at the Children’s Hospital of Philadelphia between 1991 and 2009. They were particularly interested in the notes from follow-up appointments, about whether the child was seizure free; or if seizures were still occurring, how frequent they were. Seizure frequencies were based on reports from a parent/caregiver, and they were categorised as unchanged, improved, or worse (compared to before the diet was started).
The children who responded to the diet were then divided into two groups – those who managed to remain seizure free for more than a year, and those whose seizure freedom lasted less than a year. The groups were compared in terms of demographic, age of seizure onset, number of AEDs trialled before starting the ketogenic diet and epilepsy type, to see if any of these were linked to a longer period of seizure freedom.
The team found that 65/276 children (24%) achieved at least one month of seizure freedom after starting the diet. Most of these children (45/65) had previously experienced seizures every day. The average amount of time it took to reach seizure freedom was 1.5 months.
Seizures recurred in 53 of the 65 children (82%), on average three months after the diet was initiated. Encouragingly, however, they were usually a lot less frequent than before and remained so.
Nineteen children experienced seizure-freedom for a year or longer, and nine were still seizure free 2.5 years after being weaned off the ketogenic diet.
When the researchers compared the children who were seizure free for over a year to those who were seizure free for under a year, there were no features that distinguished the two groups.
These results suggest that if seizures recur after at least a month of seizure freedom on the ketogenic diet, they are usually occasional breakthrough seizures and do not regain their original frequency. This evidence implies that when a child has achieved at least one month of seizure freedom on the ketogenic diet, it is worthwhile continuing it even if breakthrough seizures occur. This information will be useful to paediatric neurologists when managing children on the ketogenic diet in the future.