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Introduction: Multiple subpial transection (MST) has been applied to the treatment of refractory epilepsy when epileptogenic zone involves eloquent areas since 1989. However, there is a lack of data evaluating the effect of this surgical technique on the cortex as measured by Magnetic Resonance Imaging (MRI)., Patients and Methods: Ten consecutive patients (3F/7M, average age: 18.5 years) were operated on using radiating MST (average: 39; min: 19, max: 61) alone (n=3) or associated with another technique (n=7). Seven patients underwent a post-operative 3.0T MRI while 3 had a 1.5T MRI. Three patients had an early post-operative MRI and 7 a late MRI, among which 3 previously had an intraoperative MRI., Results: The MR sequences that allowed the best assessment of MST-induced changes were T2 and T2*. The traces of MST are more visible on late MRI. These discrete non-complicated stigmas of MST were observed in all 10 studied patients: on the intraoperative MRI they are seen as micro-hemorrhagic spots (hypo-T2), on the early postoperative MRI as a discreet and limited cortical edema whether associated or not with micro-hemorrhagic spots and on the late MRI as liquid micro-cavities (hyper-T2) surrounded with a fine border of hemosiderin., Conclusions: MST-induced cerebral lesions are best visualized in T2-sequences, mainly on the late postoperatively MRIs. On all the MRI examinations in this study, the MST are only associated with limited modifications of the treated cortical regions., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

There is a new focus on minimally invasive treatments for medically refractory mesial temporal lobe epilepsy (MTLE). MRI-guided laser interstitial thermal therapy (MRgLITT) is one such minimally invasive procedure, which utilizes MRI guidance and real-time feedback to ablate an epileptogenic focus. A total of 38 patients presenting exclusively with MTLE and no other lesions (including neoplasia), who underwent MRgLITT were reviewed. We evaluated a number of outcome measures, including seizure freedom, neuropsychological performance, complications, and other considerations. Eighteen (53%) had an Engel class I outcome, 10 patients had repeat procedures/operations, and 12 post-procedural complications occurred. Follow-up time ranged from 6 to 38.5months. There was a decreased length of procedure time, hospitalization time, and analgesic requirement when compared to open surgery. In cases of well-localized MTLE this procedure may offer similar (albeit slightly lower) rates of seizure freedom versus traditional surgery. MRgLITT may be an alternative treatment option for high risk surgical patients and, more importantly, could increase referrals for surgery in patients with medically refractory MTLE. However, data is limited and long-term outcomes have not been evaluated. Further investigation is required to understand the potential of this minimally invasive technique for MTLE., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Surgical epilepsy conferences are an important part of the process of determining whether a patient is a candidate for resective epilepsy surgery. At these conferences, repeat review (re-review) of the magnetic resonance images (MRIs) of the patient's head often occurs. This study assessed how often radiologic re-review at a presurgical epilepsy conference resulted in a changed interpretation of the head MRI. Charts were reviewed for 239 patients who had been presented at presurgical epilepsy conferences between 2008 and 2012. Of the 233 patients whose MRIs were re-reviewed, resective surgery was performed in 94 patients (40.3%). Forty-one patients (17.6%) had a previously undiagnosed finding, and 18 of the 41 (43.9%) underwent resective surgery. For 4 of the 41 patients (9.8%) with a previously undiagnosed pertinent finding, re-review detected abnormalities that were not amenable to surgical resection (autoimmunity or significant bilateral pathology)., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Medically refractory epilepsy is associated with significant morbidity and mortality. Surgery is a safe and effective option for some patients, however the opportunity exists to develop less invasive and more effective surgical options. To this end, multiple minimally invasive, image-guided techniques have been applied to the treatment of epilepsy. These techniques can be divided into thermoablative and disconnective techniques. Each has been described in the treatment of epilepsy only in small case series. Larger series and longer follow up periods will determine each option's place in the surgical armamentarium for the treatment of refractory epilepsy but early results are promising., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Stereoelectroencephalography (SEEG) has gained popularity as an invasive monitoring modality for epileptogenic zone (EZ) localization. The need and indications for SEEG in patients with evident brain lesions or associated abnormalities on imaging is debated. We report our experience with SEEG as a presurgical evaluation tool for patients with lesional epilepsy. A retrospective cohort study was performed of 131 patients with lesional or magnetic resonance imaging abnormality–associated medically refractory focal epilepsy who underwent resections from 2010 to 2017. Seventy-one patients had SEEG followed by resection, and 60 had no invasive recordings. Volumetric analysis of resection cavities from 3T magnetic resonance imaging was performed. Mean lesion and resection volumes for SEEG and non-SEEG were 16.2 (standard deviation [SD] = 29) versus 23.7 cm3 (SD = 38.4) and 28.1 (SD = 23.2) versus 43.6 cm3 (SD = 43.5), respectively (P = 0.009). Comparing patients with seizure recurrence and patients who remained seizure free, significantly associated variables with seizure recurrence included mean number of failed antiseizure medications (6.86 [SD = 0.32] vs. 5.75 [SD = 0.32]; P = 0.01) and in SEEG patients the mean number of electrodes implanted (8.1 [SD = 0.8] vs. 5.0 [SD = 0.8]; P = 0.005). After multivariate analysis, only failed numbers of medication remained significantly associated with seizure recurrence. Seizure outcomes did not correlate with final resection volume after SEEG evaluation. SEEG evaluation presurgically can be used to maintain the efficacy of resection and decrease the volume and subsequent risk of extensive tissue removal. We believe that this technology allows resective surgery to proceed in a subpopulation of patients with lesional epilepsy who may otherwise not have been considered surgical candidates. [ABSTRACT FROM AUTHOR]

Background: Hybrid PET/MRI can non-invasively improve localization and delineation of the epileptic focus (EF) prior to surgical resection in medically refractory epilepsy (MRE), especially when MRI is negative or equivocal. In this study, we developed a PET-guided diffusion tractography (PET/DTI) approach combining 18F-fluorodeoxyglucose PET (FDG-PET) and diffusion MRI to investigate white matter (WM) integrity in MRI-negative MRE patients and its potential impact on epilepsy surgical planning. Methods: FDG-PET and diffusion MRI of 14 MRI-negative or equivocal MRE patients were used to retrospectively pilot the PET/DTI approach. We used asymmetry index (AI) mapping of FDG-PET to detect the EF as brain areas showing the largest decrease in FDG uptake between hemispheres. Seed-based WM fiber tracking was performed on DTI images with a seed location in WM 3 mm from the EF. Fiber tractography was repeated in the contralateral brain region (opposite to EF), which served as a control for this study. WM fibers were quantified by calculating the fiber count, mean fractional anisotropy (FA), mean fiber length, and mean cross-section of each fiber bundle. WM integrity was assessed through fiber visualization and by normalizing ipsilateral fiber measurements to contralateral fiber measurements. The added value of PET/DTI in clinical decision-making was evaluated by a senior neurologist. Results: In over 60% of the patient cohort, AI mapping findings were concordant with clinical reports on seizure-onset localization and lateralization. Mean FA, fiber count, and mean fiber length were decreased in 14/14 (100%), 13/14 (93%), and 12/14 (86%) patients, respectively. PET/DTI improved diagnostic confidence in 10/14 (71%) patients and indicated that surgical candidacy be reassessed in 3/6 (50%) patients who had not undergone surgery. Conclusions: We demonstrate here the utility of AI mapping in detecting the EF based on brain regions showing decreased FDG-PET activity and, when coupled with DTI, could be a powerful tool for detecting EF and assessing WM integrity in MRI-negative epilepsy. PET/DTI could be used to further enhance clinical decision-making in epilepsy surgery. [ABSTRACT FROM AUTHOR]

A structural brain lesion in patients with drug-resistant epilepsy (DRE) greatly increases the likelihood of identification of the seizure focus and ultimately seizure-free outcome following resective epilepsy surgery. In contrast, surgical outcomes of true non-lesional DRE are less favorable. Therefore, discovery of an underlying lesion is paramount in the pre-surgical work-up of patients with DRE. Over the years, the surgical treatment of pharmacoresistant epilepsy has evolved from straightforward lesional cases to include cases with hippocampal sclerosis. With the advent of magnetic resonance imaging (MRI), most cases of mesial temporal sclerosis became more easily identifiable on pre-operative neuroimaging. With the widespread use of high-resolution MRI with epilepsy protocols over the last two decades, our ability to visualize subtle structural changes has been greatly enhanced. However, there are some cases of lesional epilepsy, which remain unidentified on these routine MRIs. In such "non-lesional" refractory epilepsies, further investigation with advanced neuroimaging techniques, including metabolic imaging, as well as electrophysiological studies may help to identify the previously non-visualized focal brain abnormalities. In this review, we outline the current status for evaluation of MRI-negative DRE. [ABSTRACT FROM AUTHOR]

Highlights: [•] Patients with refractory seizures were assessed with diffusion tensor tractography. [•] We evaluated 33 patients of, lesional and non-lesional, refractory epilepsy. [•] Diffusion changes were detected both ipsilateral and contralateral to the lesion. [•] Microstructural changes were also observed in patients with normal imaging. [•] Our findings may help in epilepsy surgery planning and prognostication. [ABSTRACT FROM AUTHOR]