The chance of cure following surgery for drug-resistant temporal lobe epilepsy. What do we know and do we need to revise our expectations?

Although surgery is often seen as a curative treatment for patients with drug-resistant temporal lobe epilepsy, little information is available how many cases can be considered cured after surgery, i.e. are seizure-free for several years without taking antiepileptic drugs (AEDs). In our review, 13 retrospective and five prospective clinical observations published since 1980 provided data on long-term seizure control off AEDs in a total of 1658 patients. No randomized studies were found. Following temporal lobe surgery, approximately one in four adult patients and approximately one in three children or adolescents can currently shown to be seizure-free for 5 years without AEDs (25%, mean of eight studies in adults, 95% CI: 21-30%, and 31%, mean of three studies in children, 95% CI: 20-41%). The rate of seizure control off AEDs seemed to be stable after 2 years of follow-up. However, as 55% of patients free of disabling seizures preferred not to discontinue their medication completely as late as 5 years after surgery, it is impossible to know if they are cured or not. No features predictive of surgical cure were detected except for better cure outcome in children versus adults with hippocampal sclerosis and in patients with typical versus atypical Ammonshorn's sclerosis or tumor in one small study each. In conclusion, the available evidence on seizure outcome off AEDs after temporal lobe surgery is based on non-randomized studies and, in part, data were collected retrospectively. A randomized controlled trial is needed to determine if, in fact only one in three to four patients with temporal lobe epilepsy undergoing surgery can be considered cured.