Abstracts

Rationale: Antiepileptic drug (AED) withdrawal is often recommended in children who become seizure free in order to avoid side effects of long-term medication use. Few studies have examined the risk of intractable epilepsy in this population and reported risks vary widely. The aim of this study is to determine the frequency of intractable epilepsy in a population-based cohort of children who withdrew AEDs after a period of seizure freedom. Methods: Records of all children ages 1 month-16 years, inclusive, who were diagnosed with new-onset epilepsy while resident in Olmsted County between 1990-2000 and had follow-up for 5 or more years after the first afebrile seizure were reviewed. The charts of children who discontinued anti-epileptic medication after achieving seizure freedom were reviewed to last follow-up to determine the proportion with seizure recurrence and those who developed intractable epilepsy (defined as failure of ≥2 AEDs for lack of efficacy and seizures greater than once every 3 months during last year of follow-up). Results: Of the 152 children diagnosed with epilepsy and treated with AEDs, 56 (37%) achieved seizure freedom (mean duration seizure free on treatment 2.3 years, SD 1.6, range 0.08-7.3 years ) and had their AEDs withdrawn. After a mean follow up of 8.0 years, (SD 3.1, range 0.33-15 years) 20 (36%) of the children experienced at least 1 seizure recurrence. Seizure recurrence occurred within 6 months in 8 (40%) of these children and over half (55%) recurred within the first year. Four (20%) recurred after more than 5 years after AED withdrawal. Of the 20 with seizure recurrence, 15 re-started AEDs, 4 remained off AEDs with no or rare recurrence, and 1 died of SUDEP at the time of first recurrence. The 15 children who re-started medication were followed for a mean of 5.7 years after re-starting medications (SD 3.5, range 0.17-11.0 years). Of these, 8 (53%) achieved seizure freedom within one year, 2 (13%) achieved seizure freedom after 2 years, and 5 (33%) never achieved seizure freedom. Only 3 (20%) met criteria for intractable epilepsy. Conclusions: Following withdrawal of AEDs for seizure freedom, 36% of the children developed seizure recurrence. Although the majority had seizure recurrence within the first year of discontinuing AEDs, 20% had recurrence after more than 5 years. Over half of the children with seizure recurrence rapidly achieved a seizure free state again with re-introduction of AEDs. Only 20% proved intractable, which is similar to the risk of intractable epilepsy at time of initial diagnosis of epilepsy in children. Children who achieve seizure freedom on AEDs can be considered for withdrawal without high risk of intractable epilepsy.