Abstracts

Rationale: To investigate the relationship between seizure outcomes and interictal epileptiform discharges (IEDs) within one month after anterior temporal lobectomy (ATL). Methods: Data were reviewed from patients who had undergone ATL for nonlesional mesial temporal epilepsy between 1987 and 2007. We included patients who had preoperative MRI, preoperative IQ test and seizure outcomes that were followed up for at least two years. Postoperative EEG within 30 days and other preoperative variables were analyzed to examine the significant factors that determine freedom from disabling seizures at two, five and 10 years after ATL and the risk factors for recurrence. Results: In total, 202 (107 left ATL, 95 right ATL) patients were enrolled in this study. Postoperative EEG was done at an average of 11 days after surgery. IEDs were noted in 29 patients (22.3%) of the 130 patients without seizure for two years after ATL compared to 31 patients (43.1%) of the 72 patients with recurrent seizures (p=0.002). Postoperaive IED remained an independent predictive factor for seizure outcomes by logistic regression (adjusted OR 2.38, 95% CI 1.18-4.81, p=0.016, 2 years postoperatively; adjusted OR 2.22, 95% CI 1.03-4.82, p=0.043, 5 years postoperatively) and Cox hazard regression analysis (adjusted HR 1.76, 95% CI 1.18-2.62, p=0.006) after controlling other predicting factors (unilateral hippocampal atrophy, history of febrile seizure and IQ tests). Conclusions: In this study, IEDs on the EEG obtained soon after surgery were associated with postoperative seizure recurrence and these results can be used in the risk assessment of seizure recurrence after ATL.