When to start antiepileptic drug treatment and with what evidence?

Where possible, the decision as to when to start antiepileptic drug treatment should be informed by the results of randomized controlled trials. For patients presenting with their first seizure, randomized controlled trials have demonstrated that compared to no or delayed treatment, antiepileptic drugs reduce the risk of a second seizure, but do not alter longer term seizure outcomes. A prognostic model has been developed to identify patients at low, medium and high risk of recurrence, to further inform treatment decisions. For patients presenting with two or more seizures, consensus holds that treatment should be initiated if the seizures were of significant symptomatology such that the patient would wish treatment, and they occurred over a period of less than 6-12 months. However, randomized controlled trials recruiting an unselected population of patients following two or more seizures have not been undertaken and the magnitude of any treatment effect is therefore unknown. This consensus is based upon data from observational studies that show a high rate of a 3rd or 4th seizures even with antiepileptic drug treatment. Recurrence risks for patients with two or more seizures of minor symptomatology (e.g., simple partial seizures) or seizures separated by long time periods of time have been investigated in a randomized control trial. They may wish to start antiepileptic drug treatment if they are in a medium or high recurrence risk group as defined by a prognostic model.