Abstracts

Rationale: Epilepsy surgery with open craniotomy with resection, in non-mesial temporal sclerosis (MST), may show < 20-50% long term success, especially in absence of hamartomas or dysplasia. Reduced morbidity and rapid recovery with MRI-guided stereotactic laser ablation surgery (SLA) provides an alternative. We show 31 total cases using non-invasive source localization with intraoperative confirmation with depth and surface electrodes. Methods: Retrospective look at 31cases of SLA in 28 patients ( ages 4-61 years; 11M, 17 F) with lesional (9) and non-lesional (19) epileptic foci from November 2012 to February, 2014. . After scalp video-EEG that located the interictal and ictal spike source, they had functional MRI (1.5 or 3T) for anatomy, language and motor centers localization. MRI showed prior brain injury (n=7), 5 prior craniotamy for tumor or epilepsy, 6 normal brain anatomy, and 7 had MST. Magnetic Source Imaging (MSI) confirming EEG source localization seen in all but 7 cases (combined EEG, fMRI data, with MSI (21/28); PET scan was done in 9 patients (2 no MEG/ 7 MST), and source localization with EEG software and no MEG in 2 patients ( 1 BEESA software, 1 EGI Geodesic localization, with PET on both). The laser system (Visualase, Inc. , Houston, TX) trajectory planning used a BrainLAB navigation system (Brainlab AG, Feldkirchen, Germany) that incorparated above data. EEG data was collected intra-operatively with Ad-Tech 8-contact depth electrode electrocortigography (ECOG; in 25/31 cases) or Ives EEG plastic electrodes (Boston, MA) were placed around site of anchor bolt for pre-and post-SLA review (N=30/31 cases). Results: Duration of follow-up ranged anywhere from 3 to 31 months after SLA. Seizure freedom 68% (19/28 total patients; MST cases, 71% (5/7), 28% (8/28) have 50-96% reduction in seizures, 4% (1/28) patient only had <25% reduction in seizure. Three patients had SLA twice, one seizure free, one over 90% reduction in seizure frequency, one SCN1B case no change. The laser ablations were performed in 28 patients: MST (7), frontal lobe (5), insula (1) , non-mesial temporal lobe, (6), occipital (4), deep cingulate parietal region(1), and multilobar including parietal-occipital, frontal-temporal, occipital -temporal, or temporal-parietal (5). No MST needed repeating. EEG(27/28 patients) showed dramatic improvement or resolution of abnormal spikes on post-SLA and long term EEG (25/28). Also MRI reconstruction showed MSI source localization was included in post-MR-SLA ablation regions. Conclusions: SLA causes lower morbidity with good outcomes rivaling or bettering traditional surgical intervention for epilepsy. Non-invasive source localization can be confirmed with intraoperative depth electrodes before SLA performed. Introperative surface EEG and long term EEG correlate to good outcome by 3 months post- SLA. Further study should confirm SLA as valid alternative in non-lesional and lesional focal epilepsy.