Effect of the revised definition of epilepsy on treatment decisions and seizure recurrence after a first epileptic seizure.

BACKGROUND

Studies on risk factors for epilepsy and seizure recurrence after a first seizure are usually based on the old definition of epilepsy with the need for two unprovoked seizures. The current definition of epilepsy allows diagnosis and treatment of epilepsy after a first seizure if the recurrence risk is >60%. We evaluate treatment decisions, seizure recurrence and risk factors for epilepsy related to the application of the new definition of epilepsy.

METHODS

Data of 629 patients with a first seizure were analyzed to investigate changes of treatment decisions and seizure recurrence after the revised definition of epilepsy. We used binary logistic regression to investigate the impact of multiple factors influencing seizure recurrence like electroencephalogram (EEG) and magnetic resonance imaging (MRI) results and administration of antiseizure medication (ASM).

RESULTS

The proportion of patients receiving ASM significantly increased from 70.4% to 80.5% (p = 0.015) following the new epilepsy definition, without any significant changes in the recurrence rate (40.8% vs. 45.5% after 2 years, p > 0.05). The presence of interictal epileptiform discharges (IED) in the EEG increased (OR = 1.98) and administration of ASM decreased (OR = 0.43) recurrence rates significantly.

CONCLUSIONS

The new definition of epilepsy was associated with increased application of ASM, but not with reduced recurrence rates. The study confirms the presence of IED as a strong risk factor for seizure recurrence and the protective effect of ASM. The influence of imaging findings, which have a strong impact on the new definition of epilepsy, could not be confirmed.