Antiepileptic drug therapy: when is epilepsy truly intractable?

We define intractable in the first 5 years of epilepsy treatment as an average of at least one seizure every 2 months. For the longer term, we define intractable as at least one seizure per year. Population studies from Chicago, IL, U.S.A., Finland, and Nova Scotia, Canada indicate that with long follow-up, many children with intractable epilepsy eventually have remission of their seizure disorder. Epilepsy is no longer intractable when the seizures stop completely. How often does a new antiepileptic drug (AED) render a child seizure-free when one or more AEDs have failed? Literature on adults with epilepsy suggests that few with chronic epilepsy who have not achieved seizure control with several AEDs will achieve complete seizure control with additional AEDs. The Nova Scotia study suggests that if a child's seizure fails to be controlled with a first AED, there is an increased risk of intractable epilepsy. Nonetheless, the chance of eventual, complete remission of epilepsy (seizure-free without AED treatment) is approximately 40%. We conclude that intractability should not be considered until there has been failure of at least three first-line AEDs. Intractable epilepsy is rare. Careful definition of the characteristics of children with intractable epilepsy who do respond completely to new AEDs will likely provide the only rational approach to treatment of children with three drug failures. Collaboration by multiple epilepsy centers will be required to gain this information.