When a person with epilepsy has been successfully seizure-free on anti-epileptic drugs (AEDs) for a number of years, it can be difficult to tell whether their remission is due to the drugs or whether their epilepsy has genuinely stopped.

If the epilepsy itself has stopped, then they could stop taking AEDs. However if the drugs have the seizures under control, stopping them could allow seizures to start again, and these may then not be controllable by simply increasing the dose back to the old levels. Patients are understandably reluctant to try this.

Researchers from the University of Turku in Finland have carried out a very long term study to look into relapse rates and outcomes. They followed 148 patients from their first seizures for an average of 37 years. Over this time, 90 patients stopped taking AEDs. Thirty-three of these patients (37%) had a seizure relapse after discontinuation. Increasing the dose of AEDs again could not achieve seizure freedom in 6 people, though a further two did become seizure free again in 10 years. The features of epilepsy that appeared to make regaining seizure freedom less likely were having an identified underlying brain disorder, and having focal epilepsy. The results of the study were published in June in Epilepsy & Behavior.

The researchers concluded that discontinuing a drug after seizure freedom will not cause a relapse in two-thirds of patients. Of the patients who do have further seizures, three-quarters will be able to achieve seizure control again on the same drug as previously, but one quarter will not. These risks need to be considered by any doctor thinking of stopping AED treatment for a patient who has been seizure free for a number of years.