Search

Objectives: Although hemispheric surgeries are among the most effective procedures for drug-resistant epilepsy (DRE) in the pediatric population, there is a large variability in seizure outcomes at the group level. A recently developed HOPS score provides individualized estimation of likelihood of seizure freedom to complement clinical judgement. The objective of this study was to develop a freely accessible online calculator that accurately predicts the probability of seizure freedom for any patient at 1-, 2-, and 5-years post-hemispherectomy., Methods: Retrospective data of all pediatric patients with DRE and seizure outcome data from the original Hemispherectomy Outcome Prediction Scale (HOPS) study were included. The primary outcome of interest was time-to-seizure recurrence. A multivariate Cox proportional-hazards regression model was developed to predict the likelihood of post-hemispheric surgery seizure freedom at three time points (1-, 2- and 5- years) based on a combination of variables identified by clinical judgment and inferential statistics predictive of the primary outcome. The final model from this study was encoded in a publicly accessible online calculator on the International Network for Epilepsy Surgery and Treatment (iNEST) website (https://hops-calculator.com/)., Results: The selected variables for inclusion in the final model included the five original HOPS variables (age at seizure onset, etiologic substrate, seizure semiology, prior non-hemispheric resective surgery, and contralateral fluorodeoxyglucose-positron emission tomography [FDG-PET] hypometabolism) and three additional variables (age at surgery, history of infantile spasms, and magnetic resonance imaging [MRI] lesion). Predictors of shorter time-to-seizure recurrence included younger age at seizure onset, prior resective surgery, generalized seizure semiology, FDG-PET hypometabolism contralateral to the side of surgery, contralateral MRI lesion, non-lesional MRI, non-stroke etiologies, and a history of infantile spasms. The area under the curve (AUC) of the final model was 73.0%., Significance: Online calculators are useful, cost-free tools that can assist physicians in risk estimation and inform joint decision-making processes with patients and families, potentially leading to greater satisfaction. Although the HOPS data was validated in the original analysis, the authors encourage external validation of this new calculator., (© 2023 The Authors. Epilepsia published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.)

Objective: Lennox-Gastaut syndrome (LGS) is a severe form of epileptic encephalopathy, presenting during the first years of life, and is very resistant to treatment. Once medical therapy has failed, palliative surgeries such as vagus nerve stimulation (VNS) or corpus callosotomy (CC) are considered. Although CC is more effective than VNS as the primary neurosurgical treatment for LGS-associated drop attacks, there are limited data regarding the added value of CC following VNS. This study aimed to assess the effectiveness of CC preceded by VNS., Methods: This multinational, multicenter retrospective study focuses on LGS children who underwent CC before the age of 18 years, following prior VNS, which failed to achieve satisfactory seizure control. Collected data included epilepsy characteristics, surgical details, epilepsy outcomes, and complications. The primary outcome of this study was a 50% reduction in drop attacks., Results: A total of 127 cases were reviewed (80 males). The median age at epilepsy onset was 6 months (interquartile range [IQR] = 3.12-22.75). The median age at VNS surgery was 7 years (IQR = 4-10), and CC was performed at a median age of 11 years (IQR = 8.76-15). The dominant seizure type was drop attacks (tonic or atonic) in 102 patients. Eighty-six patients underwent a single-stage complete CC, and 41 an anterior callosotomy. Ten patients who did not initially have a complete CC underwent a second surgery for completion of CC due to seizure persistence. Overall, there was at least a 50% reduction in drop attacks and other seizures in 83% and 60%, respectively. Permanent morbidity occurred in 1.5%, with no mortality., Significance: CC is vital in seizure control in children with LGS in whom VNS has failed. Surgical risks are low. A complete CC has a tendency toward better effectiveness than anterior CC for some seizure types., (© 2023 The Authors. Epilepsia published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.)

Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) has emerged as a popular minimally invasive alternative to open resective surgery for drug-resistant epilepsy (DRE). We sought to perform a systematic review and individual participant data meta-analysis to identify independent predictors of seizure outcome and complications following MRgLITT for DRE. Eleven databases were searched from January 1, 2010 to February 6, 2021 using the terms "MR-guided ablation therapy" and "epilepsy". Multivariable mixed-effects Cox and logistic regression identified predictors of time to seizure recurrence, seizure freedom, operative complications, and postoperative neurological deficits. From 8705 citations, 46 studies reporting on 450 MRgLITT DRE patients (mean age = 29.5 ± 18.1 years, 49.6% female) were included. Median postoperative seizure freedom and follow-up duration were 15.5 and 19.0 months, respectively. Overall, 240 (57.8%) of 415 patients (excluding palliative corpus callosotomy) were seizure-free at last follow-up. Generalized seizure semiology (hazard ratio [HR] = 1.78, p = .020) and nonlesional magnetic resonance imaging (MRI) findings (HR = 1.50, p = .032) independently predicted shorter time to seizure recurrence. Cerebral cavernous malformation (CCM; odds ratio [OR] = 7.97, p < .001) and mesial temporal sclerosis/atrophy (MTS/A; OR = 2.21, p = .011) were independently associated with greater odds of seizure freedom at last follow-up. Operative complications occurred in 28 (8.5%) of 330 patients and were independently associated with extratemporal ablations (OR = 5.40, p = .012) and nonlesional MRI studies (OR = 3.25, p = .017). Postoperative neurological deficits were observed in 53 (15.1%) of 352 patients and were independently predicted by hypothalamic hamartoma etiology (OR = 5.93, p = .006) and invasive electroencephalographic monitoring (OR = 4.83, p = .003). Overall, MRgLITT is particularly effective in treating patients with well-circumscribed lesional DRE, such as CCM and MTS/A, but less effective in nonlesional cases or lesional cases with a more diffuse epileptogenic network associated with generalized seizures. This study identifies independent predictors of seizure freedom and complications following MRgLITT that may help further guide patient selection., (© 2023 The Authors. Epilepsia published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.)

Despite the widespread use of intraoperative electrocorticography (iECoG) during resective epilepsy surgery, there are conflicting data on its overall efficacy and inability to predict benefit per pathology. Given the heterogeneity of iECoG use in resective epilepsy surgery, it is important to assess the utility of interictal-based iECoG. This individual patient data (IPD) meta-analysis seeks to identify the benefit of iECoG during resective epilepsy surgery in achieving seizure freedom for various pathologies. Embase, Scopus, and PubMed were searched from inception to January 31, 2021 using the following terms: "ecog", "electrocorticography", and "epilepsy". Articles were included if they reported seizure freedom at ≥12-month follow-up in cohorts with and without iECoG for epilepsy surgery. Non-English articles, noncomparative iECoG cohorts, and studies with <10% iECoG use were excluded. This meta-analysis followed the PRISMA 2020 guidelines. The primary outcome was seizure freedom at last follow-up and time to seizure recurrence, if applicable. Forest plots with random effects modeling assessed the relationship between iECoG use and seizure freedom. Cox regression of IPD was performed to identify predictors of longer duration of seizure freedom. Kaplan-Meier curves with log-rank test were created to visualize differences in time to seizure recurrence. Of 7504 articles identified, 18 were included for study-level analysis. iECoG was not associated with higher seizure freedom at the study level (relative risk = 1.09, 95% confidence interval [CI] = 0.96-1.23, p = .19, I 2  = 64%), but on IPD (n = 7 studies, 231 patients) iECoG use was independently associated with more favorable seizure outcomes (hazard ratio = 0.47, 95% CI = .23-.95, p = .037). In Kaplan-Meier analysis of specific pathologies, iECoG use was significantly associated with longer seizure freedom only for focal cortical dysplasia (FCD; p < .001) etiology. Number needed to treat for iECoG was 8.8, and for iECoG in FCD it was 4.7. We show iECoG seizure freedom is not achieved uniformly across centers. iECoG is particularly beneficial for FCD etiology in improving seizure freedom., (© 2022 The Authors. Epilepsia published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.)

Objective: Minimally invasive magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) has been proposed as an alternative to open epilepsy surgery, to address concerns regarding the risk of open surgery. Our primary hypothesis was that seizure freedom at 1 year after MRgLITT is noninferior to open surgery in children with drug-resistant epilepsy (DRE). The secondary hypothesis was that MRgLITT has fewer complications and shorter hospitalization than surgery. The primary objective was to compare seizure outcome of MRgLITT to open surgery in children with DRE. The secondary objective was to compare complications and length of hospitalization of the two treatments., Methods: This retrospective multicenter cohort study included children with DRE treated with MRgLITT or open surgery with 1-year follow-up. Exclusion criteria were corpus callosotomy, neurostimulation, multilobar or hemispheric surgery, and lesion with maximal dimension > 60 mm. MRgLITT patients were propensity matched to open surgery patients. The primary outcome was seizure freedom at 1 year posttreatment. The difference in seizure freedom was compared using noninferiority test, with noninferiority margin of -10%. The secondary outcomes were complications and length of hospitalization., Results: One hundred eighty-five MRgLITT patients were matched to 185 open surgery patients. Seizure freedom at 1 year follow-up was observed in 89 of 185 (48.1%) MRgLITT and 114 of 185 (61.6%) open surgery patients (difference = -13.5%, one-sided 97.5% confidence interval = -23.8% to ∞, p Noninferiority  = .79). The lower confidence interval boundary of -23.8% was below the prespecified noninferiority margin of -10%. Overall complications were lower in MRgLITT compared to open surgery (10.8% vs. 29.2%, respectively, p < .001). Hospitalization was shorter for MRgLITT than open surgery (3.1 ± 2.9 vs. 7.2 ± 6.1 days, p < .001)., Significance: Seizure outcome of MRgLITT at 1 year posttreatment was inferior to open surgery. However, MRgLITT has the advantage of better safety profile and shorter hospitalization. The findings will help counsel children and parents on the benefits and risks of MRgLITT and contribute to informed decision-making on treatment options., (© 2022 International League Against Epilepsy.)

Objective: There is substantial variability in reported seizure outcome following pediatric epilepsy surgery, and lack of individualized predictive tools that could evaluate the probability of seizure freedom postsurgery. The aim of this study was to develop and validate a supervised machine learning (ML) model for predicting seizure freedom after pediatric epilepsy surgery., Methods: This is a multicenter retrospective study of children who underwent epilepsy surgery at five pediatric epilepsy centers in North America. Clinical information, diagnostic investigations, and surgical characteristics were collected, and used as features to predict seizure-free outcome 1 year after surgery. The dataset was split randomly into 80% training and 20% testing data. Thirty-five combinations of five feature sets with seven ML classifiers were assessed on the training cohort using 10-fold cross-validation for model development. The performance of the optimal combination of ML classifier and feature set was evaluated in the testing cohort, and compared with logistic regression, a classical statistical approach., Results: Of the 801 patients included, 61.3% were seizure-free 1 year postsurgery. During model development, the best combination was XGBoost ML algorithm with five features from the univariate feature set, including number of antiseizure medications, magnetic resonance imaging lesion, age at seizure onset, video-electroencephalography concordance, and surgery type, with a mean area under the curve (AUC) of .73 (95% confidence interval [CI] = .69-.77). The combination of XGBoost and univariate feature set was then evaluated on the testing cohort and achieved an AUC of .74 (95% CI = .66-.82; sensitivity = .87, 95% CI = .81-.94; specificity = .58, 95% CI = .47-.71). The XGBoost model outperformed the logistic regression model (AUC = .72, 95% CI = .63-.80; sensitivity = .72, 95% CI = .63-.82; specificity = .66, 95% CI = .53-.77) in the testing cohort (p = .005)., Significance: This study identified important features and validated an ML algorithm, XGBoost, for predicting the probability of seizure freedom after pediatric epilepsy surgery. Improved prognostication of epilepsy surgery is critical for presurgical counseling and will inform treatment decisions., (© 2022 International League Against Epilepsy.)

Objective: This study was undertaken to determine whether the vertical parasagittal approach or the lateral peri-insular/peri-Sylvian approach to hemispheric surgery is the superior technique in achieving long-term seizure freedom., Methods: We conducted a post hoc subgroup analysis of the HOPS (Hemispheric Surgery Outcome Prediction Scale) study, an international, multicenter, retrospective cohort study that identified predictors of seizure freedom through logistic regression modeling. Only patients undergoing vertical parasagittal, lateral peri-insular/peri-Sylvian, or lateral trans-Sylvian hemispherotomy were included in this post hoc analysis. Differences in seizure freedom rates were assessed using a time-to-event method and calculated using the Kaplan-Meier survival method., Results: Data for 672 participants across 23 centers were collected on the specific hemispherotomy approach. Of these, 72 (10.7%) underwent vertical parasagittal hemispherotomy and 600 (89.3%) underwent lateral peri-insular/peri-Sylvian or trans-Sylvian hemispherotomy. Seizure freedom was obtained in 62.4% (95% confidence interval [CI] = 53.5%-70.2%) of the entire cohort at 10-year follow-up. Seizure freedom was 88.8% (95% CI = 78.9%-94.3%) at 1-year follow-up and persisted at 85.5% (95% CI = 74.7%-92.0%) across 5- and 10-year follow-up in the vertical subgroup. In contrast, seizure freedom decreased from 89.2% (95% CI = 86.3%-91.5%) at 1-year to 72.1% (95% CI = 66.9%-76.7%) at 5-year to 57.2% (95% CI = 46.6%-66.4%) at 10-year follow-up for the lateral subgroup. Log-rank test found that vertical hemispherotomy was associated with durable seizure-free progression compared to the lateral approach (p = .01). Patients undergoing the lateral hemispherotomy technique had a shorter time-to-seizure recurrence (hazard ratio = 2.56, 95% CI = 1.08-6.04, p = .03) and increased seizure recurrence odds (odds ratio = 3.67, 95% CI = 1.05-12.86, p = .04) compared to those undergoing the vertical hemispherotomy technique., Significance: This pilot study demonstrated more durable seizure freedom of the vertical technique compared to lateral hemispherotomy techniques. Further studies, such as prospective expertise-based observational studies or a randomized clinical trial, are required to determine whether a vertical approach to hemispheric surgery provides superior long-term seizure outcomes., (© 2021 The Authors. Epilepsia published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.)

Objective: To develop and validate a model to predict seizure freedom in children undergoing cerebral hemispheric surgery for the treatment of drug-resistant epilepsy., Methods: We analyzed 1267 hemispheric surgeries performed in pediatric participants across 32 centers and 12 countries to identify predictors of seizure freedom at 3 months after surgery. A multivariate logistic regression model was developed based on 70% of the dataset (training set) and validated on 30% of the dataset (validation set). Missing data were handled using multiple imputation techniques., Results: Overall, 817 of 1237 (66%) hemispheric surgeries led to seizure freedom (median follow-up = 24 months), and 1050 of 1237 (85%) were seizure-free at 12 months after surgery. A simple regression model containing age at seizure onset, presence of generalized seizure semiology, presence of contralateral 18-fluoro-2-deoxyglucose-positron emission tomography hypometabolism, etiologic substrate, and previous nonhemispheric resective surgery is predictive of seizure freedom (area under the curve = .72). A Hemispheric Surgery Outcome Prediction Scale (HOPS) score was devised that can be used to predict seizure freedom., Significance: Children most likely to benefit from hemispheric surgery can be selected and counseled through the implementation of a scale derived from a multiple regression model. Importantly, children who are unlikely to experience seizure control can be spared from the complications and deficits associated with this surgery. The HOPS score is likely to help physicians in clinical decision-making., (© 2021 International League Against Epilepsy.)

Objective: To report the feasibility, safety, and clinical outcomes of an exploratory study of MR-guided Laser Interstitial Thermal Therapy (MRgLITT) as a minimally invasive surgical procedure for the ablation of epileptogenic foci in children with drug-resistant, lesional epilepsy., Methods: Retrospective chart review of all MRgLITT procedures at a single tertiary care center. All procedures were performed using a U.S. Food and Drug Administration (FDA)-cleared surgical laser ablation system (Visualase Thermal Therapy System). Predefined clinical and surgical variables were extracted from archived medical records., Results: Seventeen patients underwent 19 MRgLITT procedures from May 2011 to January 2014. Mean age at seizure onset was 7.1 years (range 0.1-14.8 years). Mean age at surgery was 15.3 years (range 5.9-20.6 years). Surgical substrates were mixed but mainly composed of focal cortical dysplasia (n = 11). Complications occurred in four patients. Average length of hospitalization postsurgery was 1.56 days. Mean follow-up was 16.1 months (n = 16; range 3.5-35.9 months). Engel class I outcome was achieved in seven patients (7/17; 41%), Engel class II in one (1/17; 6%), Engel class III in three (3/17; 18%), and Engel class IV in six (6/17; 35%). Three patients (3/8; 38%) with class I and II outcomes and five patients (5/9; 56%) with class III and IV outcomes had at least one prior resection. Fisher's exact test was not statistically significant for the association between Engel class outcome and previous resection (p = 0.64)., Significance: This study provides descriptive results regarding the use of MRgLITT in a mixed population of pediatric, lesional, drug-resistant epilepsy cases. The ability to classify case-specific outcomes and reduce technical complications is anticipated as experience develops. Further multicenter, prospective studies are required to delineate optimal candidates for MRgLITT, and larger cohorts are needed to more accurately define outcome and complication rates., (Wiley Periodicals, Inc. © 2015 International League Against Epilepsy.)

Purpose: We present two methods of implantation for the investigation of suspected insular and perisylvian epilepsy that combine depth and subdural electrodes to capitalize on the advantages of each technique., Methods: Retrospective study of all intracranial EEG studies that included insular electrodes from 2004-2010. Patients were divided according to the implantation scheme. The first method (type 1) consisted of a craniotomy, insertion of insular electrodes after microdissection of the sylvian fissure, orthogonal implantation of mesiotemporal structures with neuronavigation, and coverage of the adjacent lobes with subdural electrodes. The second method (type 2) consisted of magnetic resonance imaging (MRI)-stereotactic frame-guided depth electrode implantation into insula and hippocampus using sagittal axes, and insertion of subdural electrodes through burr holes to cover the adjacent lobes. The combined implantations were developed and performed by one neurosurgeon (AB)., Key Findings: Nineteen patients had an intracranial study that sampled the insula, among other regions. Sixteen patients were implanted using the first method, which allowed a mean of 4, 5, 20, 15, and 42 contacts per patient to be positioned into/over the insular, mesial temporal, neocortical temporal, parietal, and frontal areas, respectively. The second method (three patients) allowed a mean of 8, 7, 16, 6, and 9 contacts per patient to sample the same areas, respectively. The four patients in whom transient neurologic deficits occurred were investigated with use of type 1 implantation., Significance: Combined depth and subdural electrodes can be used safely to investigate complex insular/perisylvian refractory epilepsy. Choice of implantation scheme should be individualized according to presurgical data and the need for functional localization., (Wiley Periodicals, Inc. © 2011 International League Against Epilepsy.)