It is possible to grow out epilepsy, so after a number of years of seizure-freedom on an anti-epileptic drug (AED), a person with epilepsy may want to consider stopping the medication. However, relapse is possible, and many people are understandably reluctant to run the risk of having more seizures.

So what is the risk? Are there any features that can predict whether a person will relapse after AED withdrawal? Dr Morten Lossius and colleagues at the University Hospital in Lorenskog, Norway, set up a trial to answer these questions.

A total of 160 people with epilepsy were included in the trial. All had been seizure-free for more than two years (in fact two-thirds had been seizure-free for more than five years); all were taking only one AED.

After 12 months on the study, 15% of people in the withdrawal group had relapsed. However, so had 7% of the people who had continued on AEDs. At this point, 86% of the people who had remained seizure-free while still taking an AED decided to withdraw as well, and after another year, a similar proportion to the first group had relapsed.

Three years later, about 80% of people who had stopped their AEDs remained seizure-free. If relapse occurred, this was usually within 12 months of coming off AEDs. There was a small but significant improvement in psychological and neurological functioning (measured with a series of questionnaires) in the people who came off AEDs.

Risk of relapse
So what have we learnt from this study? In patients with relatively easy-to-treat epilepsy, the rate of relapse after coming off AEDs after two years seizure-free is about 20%. Relapse is most likely in the first 12 months after stopping medication. We should probably expect the risk of relapse to be higher in people with epilepsy which is more resistant to treatment. This study also showed that cognitive functioning (speed and ease of thinking and reasoning) often improved by a small but significant amount when AEDs were stopped.

There was nothing to link the risk of relapse with a person's age, sex, type of epilepsy (partial or generalised), brain scan results or period spent seizure-free. Having been on carbamazepine before the study was associated with a lower risk of relapse, possibly because carbamazepine is one of the AEDs often tried first, so people who were taking it were likely to have the easiest-to-treat epilepsy. However apart from this, it's generally not possible to predict whether someone will relapse or not.

This study was published in the journal Epilepsia in March 2008. A review article was published in the May/June edition of Advances in Clinical Neuroscience & Rehabilitation.