Resective focal epilepsy surgery - Has selection of candidates changed? A systematic review

Objective: No standard, widely accepted criteria exist to determine who should be referred for an epilepsy surgical evaluation. As a result, indications for epilepsy surgery evaluation vary significantly between centers. We review the literature to assess what criteria have been used to select patients for resective epilepsy surgery and examine whether these have changed since the publication of the first epilepsy surgery randomized controlled trial in 2001. Methods: A systematic review was conducted using PubMed and EMBASE, bibliographies of reviews and book chapters identifying focal epilepsy resective series. Abstract, full text review and data abstraction (i.e. indications for surgery) were performed independently by two reviewers. Descriptive historical analysis was done to examine indications over time. Results: Out of 5061 articles related to epilepsy surgery, 384 articles met all eligibility criteria. Most common criteria for selecting patients for evaluation for resective surgery were: AED resistance (n = 303, most commonly >2 AEDs = 46), epilepsy duration (n = 53, most commonly >1 year = 42) and seizure frequency (most commonly at least one seizure/month, n = 29). Out of the prospective studies the most notable change over time (pre-2000 vs. post-2000) was failure of ≥2 AEDs (8% vs. 43% respectively, p < 0.001). Conclusions: Important variations between studies make it difficult to identify consistent criteria to guide surgical candidacy or changes in indications over time. With increasing evidence that earlier surgery is associated with better outcomes, it is recommended that patients be evaluated as soon as they have failed two AEDs, consistent with the new definition of drug resistant epilepsy. Furthermore, low seizure frequency should not be a barrier to epilepsy surgery. Anyone with drug resistant epilepsy should be promptly evaluated for possible surgery, regardless of seizure frequency.