 Children who discontinue the diet after achieving seizure freedom have about a 20 % risk of seizures returning . The length of time until recurrence is highly variable but averages two years . This risk of recurrence compares with 10 % for resective surgery ( where part of the brain is removed ) and 30 – 50 % for anticonvulsant therapy . Of those that have a recurrence , just over half can regain freedom from seizures either with anticonvulsants or by returning to the ketogenic diet . Recurrence is more likely if , despite seizure freedom , an electroencephalogram ( EEG ) shows epileptiform spikes , which indicate epileptic activity in the brain but are below the level that will cause a seizure . Recurrence is also likely if an MRI scan shows focal abnormalities ( for example , as in children with tuberous sclerosis ) . Such children may remain on the diet longer than average , and it has been suggested that children with tuberous sclerosis who achieve seizure freedom could remain on the ketogenic diet indefinitely . 
