148 Does Stereoelectroencephalograghy (SEEG) Add Value in Patients with Lesional Epilepsy?

Abstract

INTRODUCTION: Stereoelectroencephalograghy (SEEG) has been gaining popularity as an effective invasive monitoring modality for epileptogenic zone (EZ) localization. The need and indications for SEEG in patients with evident brain lesions is debated. METHODS: Retrospective case-control cohort study of 131 patients with lesional MRFE who underwent resective surgery from 2010-2017. Seventy one patients had SEEG followed by resection, and 60 had no SEEG. 3T MRI was used for pre and post-operative evaluation. Volumetric analysis of resection cavities was conducted using T1 volumetric, T2 FLAIR sequences and BrainLAB software. RESULTS: Mean age at time of surgery was 30.1 years, epilepsy duration was 18.2 years, monthly seizure frequency was 31.7 and length of follow up was 3.1 years. Comparing SEEG vs non SEEG; mean seizure frequency per month was 80.3 vs 35.1 (P value 0.67) and mean number of failed anti-seizure medications was 6.8 vs 5.8. (P value 0.03). Mean lesion and resection volumes for SEEG and non-SEEG were 16.2 vs 23.7 cm3 and 28.1 vs 43.6 cm3 respectively. Comparing patients with seizure recurrence and patients who remained seizure free, mean number of failed anti-seizure medications 6.86 vs 5.75 (P value 0.01) and mean number of electrodes implanted were 8.1 vs 5.0 (P value 0.005). CONCLUSION: In our study, seizure outcomes did not correlate with final resection volume following SEEG evaluation. The higher number of failed anti-seizure medications was the only variable found to correlate with worse outcome.