The benefit of active drug trials is dependent on aetiology in refractory focal epilepsy

Earlier studies have shown that aetiology makes a difference in the outcome of epilepsy, but there is a paucity of follow-up studies to evaluate the possibilities of achieving seizure freedom in initially refractory epilepsy.

We evaluated the cause of epilepsy based on high-resolution brain MRI and patient history in 119 consecutive thoroughly examined adult patients with refractory focal epilepsy followed up in our centre. We also evaluated the influence of aetiology and duration of epilepsy in this patient cohort on the chances of achieving 12-month remission in a 2-year follow-up.

The major finding was that a substantial group of patients achieved remission; 30 (25%) initially refractory patients achieved at least 12 months remission during follow-up. A total of 40.0% of the patients with cryptogenic aetiology had achieved 12-month remission compared with the 16.2% patients with symptomatic aetiologies (age-adjusted OR 3.74, 95% CI 1.54 to 9.07, p = 0.004). Aetiologies often considered for surgical treatment (hippocampal sclerosis, cortical dysplasia, vascular malformation, tumour and dual pathology) carried an almost six-fold risk of persistent seizures compared with cryptogenic epilepsy (age-adjusted OR 5.85, 95% CI 2.00 to 17.11, p = 0.001).

Patients with vascular malformation and dual pathology as aetiology were most refractory, none being in remission for 12 months. There were also patients achieving 12-month remission after a long period of active epilepsy. These results encourage physicians to continue with new drug trials, especially on patients with no possibilities of epilepsy surgery, as well as on those still having seizures after epilepsy surgery.