Abstracts

Rationale: The chances of remaining seizure free for very long periods are still unclear for patients undergoing surgery for mesial temporal lobe epilepsy and unilateral hippocampal sclerosis (MTLE/HS). Likewise, the impact of practical variables such as surgical technique and post-operative reduction of medication needs clarification. Methods: We followed 108 patients with unilateral MTLE/HS for 8 to 18 years and generated Kaplan-Maier survival curves for the probability of remaining seizure free over the years and for the modulating effect of medication management and surgical technique. Univariate and multivariate regression analyses were then perfomed to determine the impact of these and other variables on the long-term evolution. Results: A history of generalized tonic clonic seizures (GTCS) was present in 10% of the patients and only 16% needed intracranial EEG. The probability of remaining completely seizure-free at 12 and 18 years was 65% and 62%. Around 75% of patients have discontinued or significantly reduced antiepileptic drugs (AEDs). The type of surgical technique did not impact on outcome. Multivariate analysis showed that both a history of GTCS and remaining on full or almost full doses of AEDs significantly diminished the probability of remaining seizure free (Cox regression: p=0.003 CI: 1.84-22.41 for GTCS; p=0.048, CI: 0.07-5.27 for AED management). Conclusions: Patient selection may be the most important determinant of the chances of remaining seizure free over the years. When the epileptologic profile indicates more restricted disease, removal of neocortical structures does not lead to better chances of seizure control and the reduction or discontinuation of AED does not prevent favorable results.