Abstracts

Rationale: To analyze the seizure-free outcome after resective surgery in patients with lesional and non-lesional focal epilepsy following invasive sEEG. Methods: A cohort of consecutive patients with medically refractory focal epilepsy, evaluated with both a non-invasive evaluation protocol and invasive monitoring with personalized, stereotactically implanted depth electrodes for stereo EEG (sEEG) was analyzed. Coregistration of the post-implantation CT scan to presurgical MRI data was used for 3D reconstructions of the patients’ brain surface and mapping of neurophysiology data. Individual multimodal 3D maps of the epileptogenic zone (EZ) were used to guide subsequent tailored resections. Outcome was rated according to the Engel classification. Results: Out of 914 patients who underwent non-invasive presurgical evaluation, 85 also underwent sEEG, and 70 were included in the outcome analysis. Mean follow-up was 42 months. Excellent seizure-free outcome (Engel class I A-C) was achieved in 83% of all resected patients. There was no significant difference between patient subgroups, all did similarly well: lesional and non-lesional epilepsy (n=42, 86% vs. n=28, 79%), temporal and extra-temporal epilepsy (n=45, 80% vs. n=25, 84%), right- and left-hemispheric resections (n=44, 82% vs. n=26, 85%) and those with EZ adjacent to or distant from eloquent cortex (n=21, 86% vs. n=49, 82%). Surgical outcome was also independent of the resection volume. Conclusions: Excellent post-surgical outcome can be achieved in patients with medically refractory focal epilepsy, using individualized sEEG evaluation and tailored navigated resection, even in patients with non-lesional or extra-temporal focal epilepsies. Funding: None