Surgery for Drug-Resistant Epilepsy in Children

Identification and treatment of surgically-remediable causes of infantile epileptic spasms syndrome

INTRODUCTION

Infantile epileptic spasms syndrome (IESS) is a common developmental and epileptic encephalopathy with poor long-term outcomes. A substantial proportion of patients with IESS have a potentially surgically remediable etiology. Despite this, epilepsy surgery is underutilized in this patient group. Some surgically remediable etiologies, such as focal cortical dysplasia and malformation of cortical development with oligodendroglial hyperplasia in epilepsy (MOGHE), are under-diagnosed in infants and young children. Even when a surgically remediable etiology is recognised, for example, tuberous sclerosis or focal encephalomalacia, epilepsy surgery may be delayed or not considered due to diffuse EEG changes, unclear surgical boundaries, or concerns about operating in this age group.

AREAS COVERED

In this review, the authors discuss the common surgically remediable etiologies of IESS, their clinical and EEG features, and the imaging techniques that can aid in their diagnosis. They then describe the surgical approaches used in this patient group, and the beneficial impact that early epilepsy surgery can have on developing brain networks.

EXPERT OPINION

Epilepsy surgery remains underutilized even when a potentially surgically remediable cause is recognized. Overcoming the barriers that result in under-recognition of surgical candidates and underutilization of epilepsy surgery in IESS will improve long-term seizure and developmental outcomes.

Trends, outcomes, and complications of surgery for lesional epilepsy in infants and toddlers: A multicenter study

OBJECTIVE

To assess seizure and developmental outcomes, their predictors, and complications in 160 children who, between 1998 and 2022, underwent surgery for lesional epilepsy with curative intent before the age of 3 years. To compare trends in epilepsy surgery in this age group before and after the year 2014.

METHODS

Retrospective multicenter study. Descriptive and univariate analyses, and multivariable models for all outcomes.

RESULTS

These 160 patients (76 F; 47.5%) underwent 169 surgeries (age at surgery 20.4 ± 9.4 months). At the last follow-up (77 ± 57.4 months), 121 patients (75.6%) were in Engel class I, 106 (66.2%) of whom were in Engel class Ia. Antiseizure medications were stopped in 84 patients (52.5%). Complications requiring reoperations were observed in 16 patients (10%; 9.5% of surgeries) and unexpected permanent deficits in 12 (7.5%; 7.1% of surgeries). Postoperative cognitive functions remained unchanged in 56 patients (44.4%), improved in 51 (40.5%), and worsened in 19 (15.1%). Multivariable analyses showed that the probability of achieving Engel class Ia was lower when the duration of epilepsy was longer, patients underwent preoperative video-EEG, and unexpected postoperative permanent deficits occurred. Cognitive improvement after surgery was associated with lower preoperative seizure frequency, better preoperative developmental level, and a longer postoperative follow-up. FCDII and tumors were the histopathologies carrying a higher probability of achieving seizure freedom, while polymicrogyria was associated with a lower probability of cognitive improvement. The number of patients operated on after 2014 was higher than before (61.3% vs. 38.7%), with stable outcomes.

SIGNIFICANCE

Epilepsy surgery is effective and safe in infants and toddlers, although the complication rate is higher than seen in older patients. Shorter duration of epilepsy, lower seizure frequency, no need for video-EEG, tumors, and some malformations of cortical development are robust predictors of seizure and cognitive outcome that may be exploited to increase earlier referral.

PLAIN LANGUAGE SUMMARY

This study analyzed the results of epilepsy surgery in 160 children who had been operated on before the age of 3 years at four Italian centers between 1998 and 2022. At the last follow-up (77 ± 57.4 months), 121 patients (75.6%) were free from disabling seizures, of which 106 (66.2%) were completely seizure-free since surgery. Major surgical complications occurred in 28 patients (17.5%), which is higher than observed with epilepsy surgery in general, but similar to hemispheric/multilobar surgery. Postoperative cognitive function remained unchanged in 56 patients (44.4%), improved in 51 (40.5%), and worsened in 19 (15.1%). Epilepsy surgery is effective and safe in infants and toddlers.

Treatment odyssey to epilepsy surgery in children with focal cortical dysplasia: Risk factors for delayed surgical intervention

OBJECTIVE

To elucidate the patient's journey to epilepsy surgery and identify the risk factors contributing to surgical delay in pediatric patients with drug-resistant epilepsy (DRE) due to focal cortical dysplasia (FCD).

METHODS

A retrospective review was conducted of 93 pediatric patients who underwent curative epilepsy surgery for FCD between January 2012 and March 2023 at a tertiary epilepsy center. The Odyssey plot demonstrated the treatment process before epilepsy surgery, including key milestones of epilepsy onset, first hospital visit, epilepsy diagnosis, MRI diagnosis, DRE diagnosis, and surgery. The primary outcome was surgical delay; the duration from DRE to surgery. Multivariate linear regression models were used to examine the association between surgical delay and clinical, investigative, and treatment characteristics.

RESULTS

The median age at seizure onset was 1.3 years (interquartile range [IQR] 0.14-3.1), and at the time of surgery, it was 6 years (range 1-11). Notably, 46% experienced surgical delays exceeding two years. The Odyssey plot visually highlighted that surgical delay comprised a significant portion of the patient journey. Although most patients underwent MRI before referral, MRI abnormalities were identified before referral only in 39% of the prolonged group, compared to 70% of the non-prolonged group. Multivariate analyses showed that delayed notification of MRI abnormalities, longer duration from epilepsy onset to DRE, older age at onset, number of antiseizure medications tried, and moderate to severe intellectual disability were significantly associated with prolonged surgical delay.

CONCLUSION

Pediatric DRE patients with FCD experienced a long journey until surgery. Early and accurate identification of MRI abnormalities is important to minimize surgical delays.

Characterizing Frontal Lobe Seizure Semiology in Children

OBJECTIVE

The objective was to analyze seizure semiology in pediatric frontal lobe epilepsy patients, considering age, to localize the seizure onset zone for surgical resection in focal epilepsy.

METHODS

Fifty patients were identified retrospectively, who achieved seizure freedom after frontal lobe resective surgery at Great Ormond Street Hospital. Video-electroencephalography recordings of preoperative ictal seizure semiology were analyzed, stratifying the data based on resection region (mesial or lateral frontal lobe) and age at surgery (≤4 vs >4).

RESULTS

Pediatric frontal lobe epilepsy is characterized by frequent, short, complex seizures, similar to adult cohorts. Children with mesial onset had higher occurrence of head deviation (either direction: 55.6% vs 17.4%; p = 0.02) and contralateral head deviation (22.2% vs 0.0%; p = 0.03), ictal body-turning (55.6% vs 13.0%; p = 0.006; ipsilateral: 55.6% vs 4.3%; p = 0.0003), and complex motor signs (88.9% vs 56.5%; p = 0.037). Both age groups (≤4 and >4 years) showed hyperkinetic features (21.1% vs 32.1%), contrary to previous reports. The very young group showed more myoclonic (36.8% vs 3.6%; p = 0.005) and hypomotor features (31.6% vs 0.0%; p = 0.003), and fewer behavioral features (36.8% vs 71.4%; p = 0.03) and reduced responsiveness (31.6% vs 78.6%; p = 0.002).

INTERPRETATION

This study presents the most extensive semiological analysis of children with confirmed frontal lobe epilepsy. It identifies semiological features that aid in differentiating between mesial and lateral onset. Despite age-dependent differences, typical frontal lobe features, including hyperkinetic seizures, are observed even in very young children. A better understanding of pediatric seizure semiology may enhance the accuracy of onset identification, and enable earlier presurgical evaluation, improving postsurgical outcomes. ANN NEUROL 2024;95:1138-1148.

EANM practice guidelines for an appropriate use of PET and SPECT for patients with epilepsy

Epilepsy is one of the most frequent neurological conditions with an estimated prevalence of more than 50 million people worldwide and an annual incidence of two million. Although pharmacotherapy with anti-seizure medication (ASM) is the treatment of choice, ~30% of patients with epilepsy do not respond to ASM and become drug resistant. Focal epilepsy is the most frequent form of epilepsy. In patients with drug-resistant focal epilepsy, epilepsy surgery is a treatment option depending on the localisation of the seizure focus for seizure relief or seizure freedom with consecutive improvement in quality of life. Beside examinations such as scalp video/electroencephalography (EEG) telemetry, structural, and functional magnetic resonance imaging (MRI), which are primary standard tools for the diagnostic work-up and therapy management of epilepsy patients, molecular neuroimaging using different radiopharmaceuticals with single-photon emission computed tomography (SPECT) and positron emission tomography (PET) influences and impacts on therapy decisions. To date, there are no literature-based praxis recommendations for the use of Nuclear Medicine (NM) imaging procedures in epilepsy. The aims of these guidelines are to assist in understanding the role and challenges of radiotracer imaging for epilepsy; to provide practical information for performing different molecular imaging procedures for epilepsy; and to provide an algorithm for selecting the most appropriate imaging procedures in specific clinical situations based on current literature. These guidelines are written and authorized by the European Association of Nuclear Medicine (EANM) to promote optimal epilepsy imaging, especially in the presurgical setting in children, adolescents, and adults with focal epilepsy. They will assist NM healthcare professionals and also specialists such as Neurologists, Neurophysiologists, Neurosurgeons, Psychiatrists, Psychologists, and others involved in epilepsy management in the detection and interpretation of epileptic seizure onset zone (SOZ) for further treatment decision. The information provided should be applied according to local laws and regulations as well as the availability of various radiopharmaceuticals and imaging modalities.

Epilepsy surgery in adults older than 50 years: A systematic review and meta-analysis

OBJECTIVE

Despite the general safety and efficacy of epilepsy surgery, there is evidence that epilepsy surgery remains underutilized. Although there are an increasing number of studies reporting epilepsy surgery in older adults, there is no consensus on whether epilepsy surgery is efficacious or safe for this population. Our objective was to systematically assess the efficacy as well as safety of resective surgery in people aged 50 years or older with drug-resistant epilepsy.

METHODS

We considered studies that examine the efficacy and safety of epilepsy surgery in adults aged 50 years and older. Study eligibility was limited to studies carried out after 1990, with a minimum of 10 participants and 6 months of follow-up. We searched the following databases for published studies: Ovid MEDLINE, Ovid Embase, Cumulative Index to Nursing and Allied Health Literature, PsychInfo, and Web of Science Conference Proceedings Citation Index - Science. The risk of bias of each included study was independently assessed by two reviewers using the MINORS (Methodological Index for Non-Randomized Studies) instrument.

RESULTS

Eleven case series and 14 cohort studies met the criteria for inclusion, for a total of 1111 older adults who underwent epilepsy surgery along with 4111 adults younger than 50 years as control groups. The pooled cumulative incidence of older adults achieving seizure freedom after resective surgery was 70.1% (95% confidence interval [CI] = 65.3-74.7). There was no evident difference in the incidence of seizure freedom among older adults as compared to younger adults (risk ratio [RR] = 1.05, 95% CI = .97-1.14) in cohort studies. The pooled cumulative incidence of perioperative complications in older adults was 26.2% (95% CI = 21.3-31.7). Among them, 7.5% (95% CI = 5.8-9.5) experienced major complications. Older adults were significantly more at risk of experiencing any complication than younger adults (RR = 2.8, 95% CI = 1.5-5.4).

SIGNIFICANCE

Despite important considerations, epilepsy surgery may be considered appropriate among carefully selected individuals older than 50 years.

Use of Recommended Neurodiagnostic Evaluation Among Patients With Drug-Resistant Epilepsy

Importance

Interdisciplinary practice parameters recommend that patients with drug-resistant epilepsy (DRE) undergo comprehensive neurodiagnostic evaluation, including presurgical assessment. Reporting from specialized centers suggests long delays to referral and underuse of surgery; however, longitudinal data are limited to characterize neurodiagnostic evaluation among patients with DRE in more diverse US settings and populations.

Objective

To examine the rate and factors associated with neurodiagnostic studies and comprehensive evaluation among patients with DRE within 3 US cohorts.

Design, Setting, and Participants

A retrospective cross-sectional study was conducted using the Observational Medical Outcomes Partnership Common Data Model including US multistate Medicaid data, commercial claims data, and Columbia University Medical Center (CUMC) electronic health record data. Patients meeting a validated computable phenotype algorithm for DRE between January 1, 2015, and April 1, 2020, were included. No eligible participants were excluded.

Exposure

Demographic and clinical variables were queried.

Main Outcomes and Measures

The proportion of patients receiving a composite proxy for comprehensive neurodiagnostic evaluation, including (1) magnetic resonance or other advanced brain imaging, (2) video electroencephalography, and (3) neuropsychological evaluation within 2 years of meeting the inclusion criteria.

Results

A total of 33 542 patients with DRE were included in the Medicaid cohort, 22 496 in the commercial insurance cohort, and 2741 in the CUMC database. A total of 31 516 patients (53.6%) were women. The proportion of patients meeting the comprehensive evaluation main outcome in the Medicaid cohort was 4.5% (n = 1520); in the commercial insurance cohort, 8.0% (n = 1796); and in the CUMC cohort, 14.3% (n = 393). Video electroencephalography (24.9% Medicaid, 28.4% commercial, 63.2% CUMC) and magnetic resonance imaging of the brain (35.6% Medicaid, 43.4% commercial, 52.6% CUMC) were performed more regularly than neuropsychological evaluation (13.0% Medicaid, 16.6% commercial, 19.2% CUMC) or advanced imaging (3.2% Medicaid, 5.4% commercial, 13.1% CUMC). Factors independently associated with greater odds of evaluation across all 3 data sets included the number of inpatient and outpatient nonemergency epilepsy visits and focal rather than generalized epilepsy.

Conclusions and Relevance

The findings of this study suggest there is a gap in the use of diagnostic studies to evaluate patients with DRE. Care setting, insurance type, frequency of nonemergency visits, and epilepsy type are all associated with evaluation. A common data model can be used to measure adherence with best practices across a variety of observational data sources.

Evaluation of Utility of Invasive Electroencephalography for Definitive Surgery in Patients with Drug-Resistant Epilepsy: A Systematic Review and Meta-Analysis

When noninvasive tests are unable to define the epileptogenic zone in patients, intracranial electroencephalography (iEEG) is a method of localizing the epileptogenic zone. Compared with noninvasive evaluations, it offers more precise information about patterns of epileptiform activity, which results in useful diagnostic information that supports surgical decision-making. The primary aim of the present study was to assess the utility of iEEG for definitive surgery for patients with drug-resistant epilepsy. Online databases such as PubMed, Medline, Embase, Scopus, Cochrane Library, Web of Science, and IEEE Xplore were searched for MeSH terms and free-text keywords. The ROBINS I (risk of bias in non-randomized studies - of interventions) critical appraisal tool was used for quality assessment. The prevalence from different studies was pooled together using the inverse variance heterogeneity method. Egger's regression analysis and funnel plot were used to evaluate publication bias. The systematic review included 18 studies, and the meta-analysis included 10 studies to estimate the prevalence of seizure freedom (Engel class I) in patients undergoing surgery after iEEG. A total of 526 patients were included in the meta-analysis. The follow-up period ranged from 1 to 10 years. The overall pooled estimate of the prevalence of seizure freedom (Engel class I) for patients undergoing surgery after iEEG was 53% (95% confidence interval, 44%-62%). The results additionally demonstrated that 12 studies had a moderate risk of bias and 6 had a low risk. Future studies are crucial to enhance our understanding of iEEG to guide patient choices and unravel their implications.

Statistical analyses of ordinal outcomes in randomised controlled trials: a scoping review

BACKGROUND

Randomised controlled trials (RCTs) aim to estimate the causal effect of one or more interventions relative to a control. One type of outcome that can be of interest in an RCT is an ordinal outcome, which is useful to answer clinical questions regarding complex and evolving patient states. The target parameter of interest for an ordinal outcome depends on the research question and the assumptions the analyst is willing to make. This review aimed to provide an overview of how ordinal outcomes have been used and analysed in RCTs.

METHODS

The review included RCTs with an ordinal primary or secondary outcome published between 2017 and 2022 in four highly ranked medical journals (the British Medical Journal, New England Journal of Medicine, The Lancet, and the Journal of the American Medical Association) identified through PubMed. Details regarding the study setting, design, the target parameter, and statistical methods used to analyse the ordinal outcome were extracted.

RESULTS

The search identified 309 studies, of which 144 were eligible for inclusion. The most used target parameter was an odds ratio, reported in 78 (54%) studies. The ordinal outcome was dichotomised for analysis in 47 ( 33 % ) studies, and the most common statistical model used to analyse the ordinal outcome on the full ordinal scale was the proportional odds model (64 [ 44 % ] studies). Notably, 86 (60%) studies did not explicitly check or describe the robustness of the assumptions for the statistical method(s) used.

CONCLUSIONS

The results of this review indicate that in RCTs that use an ordinal outcome, there is variation in the target parameter and the analytical approaches used, with many dichotomising the ordinal outcome. Few studies provided assurance regarding the appropriateness of the assumptions and methods used to analyse the ordinal outcome. More guidance is needed to improve the transparent reporting of the analysis of ordinal outcomes in future trials.

The clinical, imaging, pathological and genetic landscape of bottom-of-sulcus dysplasia

Bottom-of-sulcus dysplasia (BOSD) is increasingly recognized as a cause of drug-resistant, surgically-remediable, focal epilepsy, often in seemingly MRI-negative patients. We describe the clinical manifestations, morphological features, localization patterns and genetics of BOSD, with the aims of improving management and understanding pathogenesis. We studied 85 patients with BOSD diagnosed between 2005-2022. Presenting seizure and EEG characteristics, clinical course, genetic findings and treatment response were obtained from medical records. MRI (3 T) and 18F-FDG-PET scans were reviewed systematically for BOSD morphology and metabolism. Histopathological analysis and tissue genetic testing were performed in 64 operated patients. BOSD locations were transposed to common imaging space to study anatomical location, functional network localization and relationship to normal MTOR gene expression. All patients presented with stereotyped focal seizures with rapidly escalating frequency, prompting hospitalization in 48%. Despite 42% patients having seizure remissions, usually with sodium channel blocking medications, most eventually became drug-resistant and underwent surgery (86% seizure-free). Prior developmental delay was uncommon but intellectual, language and executive dysfunction were present in 24%, 48% and 29% when assessed preoperatively, low intellect being associated with greater epilepsy duration. BOSDs were missed on initial MRI in 68%, being ultimately recognized following repeat MRI, 18F-FDG-PET or image postprocessing. MRI features were grey-white junction blurring (100%), cortical thickening (91%), transmantle band (62%), increased cortical T1 signal (46%) and increased subcortical FLAIR signal (26%). BOSD hypometabolism was present on 18F-FDG-PET in 99%. Additional areas of cortical malformation or grey matter heterotopia were present in eight patients. BOSDs predominated in frontal and pericentral cortex and related functional networks, mostly sparing temporal and occipital cortex, and limbic and visual networks. Genetic testing yielded pathogenic mTOR pathway variants in 63% patients, including somatic MTOR variants in 47% operated patients and germline DEPDC5 or NPRL3 variants in 73% patients with familial focal epilepsy. BOSDs tended to occur in regions where the healthy brain normally shows lower MTOR expression, suggesting these regions may be more vulnerable to upregulation of MTOR activity. Consistent with the existing literature, these results highlight (i) clinical features raising suspicion of BOSD; (ii) the role of somatic and germline mTOR pathway variants in patients with sporadic and familial focal epilepsy associated with BOSD; and (iii) the role of 18F-FDG-PET alongside high-field MRI in detecting subtle BOSD. The anatomical and functional distribution of BOSDs likely explain their seizure, EEG and cognitive manifestations and may relate to relative MTOR expression.

Evidence based noninvasive presurgical evaluation for patients with drug resistant epilepsies

PURPOSE OF REVIEW

To review the current practices and evidence for the diagnostic accuracy and the benefits of presurgical evaluation.

RECENT FINDINGS

Preoperative evaluation of patients with drug-resistant focal epilepsies and subsequent epilepsy surgery leads to a significant proportion of seizure-free patients. Even those who are not completely seizure free postoperatively often experience improved quality of life with better social integration. Systematic reviews and meta-analysis on the diagnostic accuracy are available for Video-electroencephalographic (EEG) monitoring, magnetic resonance imaging (MRI), electric and magnetic source imaging, and functional MRI for lateralization of language and memory. There are currently no evidence-based international guidelines for presurgical evaluation and epilepsy surgery.

SUMMARY

Presurgical evaluation is a complex multidisciplinary and multiprofessional clinical pathway. We rely on limited consensus-based recommendations regarding the required staffing or methodological expertise in epilepsy centers.

The Pediatric Epilepsy Surgery Interest Group (PESIG) under the auspice of the ISPN Research Committee: Availability of relevant technology and geographical distribution

PURPOSE

Epilepsy surgery for pediatric drug-resistant epilepsy has been shown to improve seizure control, enhance patient and family QoL, and reduce mortality. However, diagnostic tools and surgical capacity are less accessible worldwide. The International Society Pediatric Neurosurgery (ISPN) has established a Pediatric Epilepsy Surgery Interest Group (PESIG), aiming to enhance global collaboration in research and educational aspects. The goals of this manuscript are to introduce PESIG and analyze geographical differences of epilepsy surgery and technology availability.

METHODS

PESIG was established (2022) following an ISPN executive board decision. Using a standardized form, we surveyed the PESIG members, collecting and analyzing data regarding geographical distribution, and availability of various epilepsy treatment-related technologies.

RESULTS

Two hundred eighty-two members registered in PESIG from 70 countries, over 6 continents, were included. We categorized the countries by GDP as follows: low, lower-medium, upper-medium, and high income. The most commonly available technology was vagus nerve stimulation 68%. Stereoelectroencephalography was available for 58%. North America had statistically significant greater availability compared to other continents. Europe had greater availability compared to Africa, Asia, and South (Latin) America. Asia had greater availability compared to Africa. High-income countries had statistically significant greater availability compared to other income groups; there was no significant difference between the other income-level subgroups.

CONCLUSION

There is a clear discrepancy between countries and continents regarding access to epilepsy surgery technologies. This strengthens the need for collaboration between neurologists and neurosurgeons from around the world, to enhance medical education and training, as well as to increase technological availability.

Pediatric neuromodulation for drug-resistant epilepsy: Survey of current practices, techniques, and outcomes across US epilepsy centers

Neuromodulation via Responsive Neurostimulation (RNS) or Deep Brain Stimulation (DBS) is an emerging treatment strategy for pediatric drug-resistant epilepsy (DRE). Knowledge gaps exist in patient selection, surgical technique, and perioperative care. Here, we use an expert survey to clarify practices. Thirty-two members of the Pediatric Epilepsy Research Consortium were surveyed using REDCap. Respondents were from 17 pediatric epilepsy centers (missing data in one): Four centers implant RNS only while 13 implant both RNS and DBS. Thirteen RNS programs commenced in or before 2020, and 10 of 12 DBS programs began thereafter. The busiest six centers implant 6-10 new RNS devices per year; all DBS programs implant <5 annually. The youngest RNS patient was 3 years old. Most centers (11/12) utilize MP2RAGE and/or FGATIR sequences for planning. Centromedian thalamic nuclei were the unanimous target for Lennox-Gastaut syndrome. Surgeon exposure to neuromodulation occurred mostly in clinical practice (14/17). Clinically significant hemorrhage (n = 2) or infection (n = 3) were rare. Meaningful seizure reduction (>50%) was reported by 81% (13/16) of centers. RNS and DBS are rapidly evolving treatment modalities for safe and effective treatment of pediatric DRE. There is increasing interest in multicenter collaboration to gain knowledge and facilitate dialogue. PLAIN LANGUAGE SUMMARY: We surveyed 32 pediatric epilepsy centers in USA to highlight current practices of intracranial neuromodulation. Of the 17 that replied, we found that most centers are implanting thalamic targets in pediatric drug-resistant epilepsy using the RNS device. DBS device is starting to be used in pediatric epilepsy, especially after 2020. Different strategies for target identification are enumerated. This study serves as a starting point for future collaborative research.

Negative MRI and a seizure onset zone close to eloquent areas in FCD type II: Application of MRg-LiTT after a SEEG re-evaluation in pediatric patients with a previous failed surgery

OBJECTIVE

Negative MRI and an epileptogenic zone (EZ) adjacent to eloquent areas are two main issues that can be encountered during pre-surgical evaluation for epilepsy surgery. Focal Cortical Dysplasia type II (FCD type II) is the most common aetiology underlying a negative MRI. The objective of this study is to present three cases of pediatric patients exhibiting negative MRI and a seizure onset zone close to eloquent areas, who previously underwent traditional open surgery or SEEG-guided radiofrequency thermocoagulations (RF-TC). After seizure seizure recrudescence, pre-surgical SEEG was re-evaluated and Magnetic Resonance-guided laser interstitial thermal therapy (MRg-LiTT) was performed. We discuss the SEEG patterns, the planning of laser probes trajectories and the outcomes one year after the procedure.

METHODS

Pediatric patients who underwent SEEG followed by MRg-LiTT for drug-resistant epilepsy associated with FCD type II at our Centre were included. Pre-surgical videoEEG (vEEG), stereoEEG (sEEG), and MRI were reviewed. Post-procedure clinical outcome (measured by Engel score) and complications rates were evaluated.

RESULTS

Three patients underwent 3 MRg-LiTT procedures from January 2022 to June 2022. Epileptogenic zone was previously studied via SEEG in all the patients. All the three patients pre-surgical MRI was deemed negative. Mean age at seizure onset was 47 months (21-96 months), mean age at MRg-LiTT was 12 years (10 years 10 months - 12 years 9 months). Engel class Ia outcome was achieved in patients #2 and #3, Engel class Ib in patient #1. Mean follow-up length was of 17 months (13 months - 20 months). Complications occurred in one patient (patient #2, extradural hematoma).

CONCLUSIONS

The combined use of SEEG and MRg-LiTT in complex cases can lead to good outcomes both as a rescue therapy after failed surgery, but also as an alternative to open surgery after a successful SEEG-guided Radiofrequency Thermocoagulation (RF-TC). Specific SEEG patterns and a previous good outcome from RF-TC can be predictors of a favourable outcome.

Surgical Outcome of Pharmaco Refractory Epilepsy in the National Epilepsy Center of Sri Lanka

BACKGROUND

The National Epilepsy Center (NEC) in Sri Lanka was established in 2017. Seizure outcome, effects on quality of life (QOL) and surgical complications among nonpediatric patients who underwent epilepsy surgery from October 2017 to February 2023 are described.

METHODS

Nineteen patients (≥14 years) underwent epilepsy surgery at the NEC. We used Engel classification and Quality of Life in Epilepsy 31 (QOLIE-31) questionnaire to assess seizure outcome and QOL respectively. Surgical complications were categorized into neurological and complications related to surgery.

RESULTS

Nine female and 10 male patients underwent surgery (mean age 27.5 years (range 14-44 years). The mean follow-up duration was 10.5 months (range 6-55 months). Twelve patients underwent temporal lobe resections. At 6-months follow-up, 83.3% (10/12) had favorable seizure outcomes with Engel class I/II. At 1-year follow-up 6/8 patients (75.0%) and at 2-year follow-up, 5/7 patients (71.4%) had a favorable outcome. Seven patients had extra-temporal lobe surgeries and one defaulted. Seizure freedom was observed in 6/6 at 6 months, 3/3 at 1-year, and 2/2 at 2-year follow-up. Five patients (26.3%) experienced minor post-operative surgical site infection. Two (11.1%) had persistent quadrantanopia. Meaningful improvement in QOL (change in QOLIE-31 score ≥11.8) was observed irrespective of seizure outcome or type of surgery (P < 0.001).

CONCLUSIONS

Epilepsy surgery is effective in developing countries. Seizure outcomes in our patients are comparable to those worldwide. Clinically important QOL improvement was observed in our series. This is the first published data on epilepsy surgery outcomes in nonpediatric patients from Sri Lanka.

Ectopic HCN4 Provides a Target Biomarker for the Genetic Spectrum of mTORopathies

Background and Objectives

Pathogenic variants in PI3K-AKT-mTOR pathway and GATOR1 complex genes resulting in hyperactivation of mechanistic target of rapamycin (mTOR) complex 1 are a major cause of drug-resistant epilepsy and focal cortical malformations (FCM). Resective neurosurgery is often required to achieve seizure control in patients with mTORopathies due to lack of effectiveness of nonsurgical therapies, including antiseizure medication and mTOR inhibitors. Elevated hyperpolarization-activated cyclic nucleotide-gated potassium channel isoform 4 (HCN4) has been proposed as a key marker in some mTOR-related brain malformations. This study aimed to investigate HCN4 as a biomarker in the brain across the genetic spectrum of mTORopathies in humans.

Methods

Our study investigated the relative steady-state levels and cellular localization of HCN4 in resected human brain tissue from 18 individuals with mTORopathies (3 individuals with tuberous sclerosis complex (TSC) due to TSC2 variants, 5 individuals with focal cortical dysplasia type IIA (FCD IIA) due to genetic variants in MTOR, AKT3, and PIK3CA, and 10 individuals with FCD IIB due to variants in TSC1, MTOR, RHEB, DEPDC5, or NPRL3).

Results

Elevated HCN4 was observed to be highly restricted to abnormal cell types (dysmorphic neurons and balloon cells) in brain tissue from all mTORopathy tissues (p < 0.0001) compared with those in controls, regardless of genetic cause or variant allele frequency. Elevated HCN4 was not observed in controls or individuals with non-mTOR-related focal epilepsy due to pathogenic variants in ATP1A3, SLC35A2, or FGFR1.

Discussion

HCN4 provides a biomarker for the genetic spectrum of mTORopathies and may present a potential therapeutic target for seizure control in mTOR-related epilepsy.

Lesion volume and spike frequency on EEG impact perfusion values in focal cortical dysplasia: a pediatric arterial spin labeling study

Arterial spin labelling (ASL), an MRI sequence non-invasively imaging brain perfusion, has yielded promising results in the presurgical workup of children with focal cortical dysplasia (FCD)-related epilepsy. However, the interpretation of ASL-derived perfusion patterns remains unclear. Hence, we compared ASL qualitative and quantitative findings to their clinical, EEG, and MRI counterparts. We included children with focal structural epilepsy related to an MRI-detectable FCD who underwent single delay pseudo-continuous ASL. ASL perfusion changes were assessed qualitatively by visual inspection and quantitatively by estimating the asymmetry index (AI). We considered 18 scans from 15 children. 16 of 18 (89%) scans showed FCD-related perfusion changes: 10 were hypoperfused, whereas six were hyperperfused. Nine scans had perfusion changes larger than and seven equal to the FCD extent on anatomical images. Hyperperfusion was associated with frequent interictal spikes on EEG (p = 0.047). Perfusion changes in ASL larger than the FCD corresponded to larger lesions (p = 0.017). Higher AI values were determined by frequent interictal spikes on EEG (p = 0.004). ASL showed FCD-related perfusion changes in most cases. Further, higher spike frequency on EEG may increase ASL changes in affected children. These observations may facilitate the interpretation of ASL findings, improving treatment management, counselling, and prognostication in children with FCD-related epilepsy.

Predictors of seizure outcomes in stereo-electroencephalography-guided radio-frequency thermocoagulation for MRI-negative epilepsy

Background

One-third of intractable epilepsy patients have no visually identifiable focus for neurosurgery based on imaging tests [magnetic resonance imaging (MRI)-negative cases]. Stereo-electroencephalography-guided radio-frequency thermocoagulation (SEEG-guided RF-TC) is utilized in the clinical treatment of epilepsy to lower the incidence of complications post-open surgery.

Objective

This study aimed to identify prognostic factors and long-term seizure outcomes in SEEG-guided RF-TC for patients with MRI-negative epilepsy.

Design

This was a single-center retrospective cohort study.

Methods

We included 30 patients who had undergone SEEG-guided RF-TC at Sanbo Brain Hospital, Capital Medical University, from April 2015 to December 2019. The probability of remaining seizure-free and the plotted survival curves were analyzed. Prognostic factors were analyzed using log-rank tests in univariate analysis and the Cox regression model in multivariate analysis.

Results

With a mean time of 31.07 ± 2.64 months (median 30.00, interquartile range: 18.00-40.00 months), 11 out of 30 patients (36.7%) were classified as International League Against Epilepsy class 1 in the last follow-up. The mean time of remaining seizure-free was 21.33 ± 4.55 months [95% confidence interval (CI) 12.41-30.25], and the median time was 3.00 ± 0.54 months (95% CI 1.94-4.06). Despite falling in the initial year, the probability of remaining seizure-free gradually stabilizes in the subsequent years. The patients were more likely to obtain seizure freedom when the epileptogenic zone was located in the insular lobe or with one focus on the limbic system (p = 0.034, hazard ratio 5.019, 95% CI 1.125-22.387).

Conclusion

Our findings may be applied to guide individualized surgical interventions and help clinicians make better decisions.

Etiological analysis of 167 cases of drug-resistant epilepsy in children

BACKGROUND

To analyze the etiological distribution characteristics of drug-resistant epilepsy (DRE) in children, with the aim of providing valuable perspectives to enhance clinical practice.

METHODS

In this retrospective study, clinical data were collected on 167 children with DRE who were hospitalized between January 2020 and December 2022, including gender, age of onset, seizure types, video electroencephalogram(VEEG) recordings, neuroimaging, and genetic testing results. Based on the etiology of epilepsy, the enrolled children were categorized into different groups. The rank-sum test was conducted to compare the age of onset for different etiologies.

RESULTS

Of the 167 cases, 89 (53.3%) had a clear etiology. Among them, structural factors account for 23.4%, genetic factors for 19.2%, multiple factors for 7.2%, and immunological factors for 3.6%. The age of onset was significantly earlier in children with genetic causes than those with structural (P < 0.001) or immunological (P = 0.001) causes.

CONCLUSIONS

More than half of children with DRE have a distinct underlying cause, predominantly attributed to structural factors, followed by genetic factors. Genetic etiology primarily manifests at an early age, especially among children aged less than one year. This underscores the need for proactive enhancements in genetic testing to unveil the underlying causes and subsequently guide treatment protocols.

Resective epilepsy surgery and its impact on depression in adults: a systematic review, meta-analysis, and implications for future research

BACKGROUND

How epilepsy surgery influences the bidirectional relationship of epilepsy and depression remains poorly defined.

METHOD

For a better understanding of this question, we conducted a systematic review and meta-analysis of risk ratio on depression prevalence before and after epilepsy surgery, using Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. Three databases were comprehensively screened for all studies assessing depression before and after resective surgery in adult epileptic patients until 8 October 2022. Studies were included if depression was assessed before and after epilepsy surgery regardless of the time of follow-up. A total of 1917 studies were screened for eligibility and 91 full-texts up for inclusion; 35 studies were finally included, 25 studies and 2563 patients were included in main meta-analysis and 10 for exploratory analysis. Risk of bias was assessed using Risk Of Bias In Non-randomised Studies - of Interventions (ROBINS-I) from Cochrane. To derive the pooled depression rates before and after surgery, a meta-analysis with inversed-variance was performed using random-effects logistic models with Peto's correction and a 95% CI. Heterogeneity was assessed with Cochran's Q-test along with its derived measure of inconsistency I2.

RESULTS

Overall, the depression rates before and after resective epilepsy surgery were 0.70 (0.53 to 0.91) 95% CI, suggesting that the rate of depression at last follow-up evaluation tends to decrease after Resective Epilepsy Surgery (RES). Subgroup analysis suggest a positive long-term effect appears with a significant lower rates of depression already 6 months (0.61 (0.38 to 0.98)), after surgery which is maintained over time after 1 year (0.53 (0.31 to 0.90)), and after 2 years (0.62 (0.42 to 0.92)).

CONCLUSION

This important finding should be taken in consideration before resective surgery for drug-resistant epilepsies. However, prospective studies should be conducted to characterise which patient, at the individual level, might be at risk of de novo or worsening of depression.

PROSPERO REGISTRATION NUMBER

CRD42022355386.

Effective connectivity relates seizure outcome to electrode placement in responsive neurostimulation

Responsive neurostimulation is a closed-loop neuromodulation therapy for drug resistant focal epilepsy. Responsive neurostimulation electrodes are placed near ictal onset zones so as to enable detection of epileptiform activity and deliver electrical stimulation. There is no standard approach for determining the optimal placement of responsive neurostimulation electrodes. Clinicians make this determination based on presurgical tests, such as MRI, EEG, magnetoencephalography, ictal single-photon emission computed tomography and intracranial EEG. Currently functional connectivity measures are not being used in determining the placement of responsive neurostimulation electrodes. Cortico-cortical evoked potentials are a measure of effective functional connectivity. Cortico-cortical evoked potentials are generated by direct single-pulse electrical stimulation and can be used to investigate cortico-cortical connections in vivo. We hypothesized that the presence of high amplitude cortico-cortical evoked potentials, recorded during intracranial EEG monitoring, near the eventual responsive neurostimulation contact sites is predictive of better outcomes from its therapy. We retrospectively reviewed 12 patients in whom cortico-cortical evoked potentials were obtained during stereoelectroencephalography evaluation and subsequently underwent responsive neurostimulation therapy. We studied the relationship between cortico-cortical evoked potentials, the eventual responsive neurostimulation electrode locations and seizure reduction. Directional connectivity indicated by cortico-cortical evoked potentials can categorize stereoelectroencephalography electrodes as either receiver nodes/in-degree (an area of greater inward connectivity) or projection nodes/out-degree (greater outward connectivity). The follow-up period for seizure reduction ranged from 1.3-4.8 years (median 2.7) after responsive neurostimulation therapy started. Stereoelectroencephalography electrodes closest to the eventual responsive neurostimulation contact site tended to show larger in-degree cortico-cortical evoked potentials, especially for the early latency cortico-cortical evoked potentials period (10-60 ms period) in six out of 12 patients. Stereoelectroencephalography electrodes closest to the responsive neurostimulation contacts (≤5 mm) also had greater significant out-degree in the early cortico-cortical evoked potentials latency period than those further away (≥10 mm) (P < 0.05). Additionally, significant correlation was noted between in-degree cortico-cortical evoked potentials and greater seizure reduction with responsive neurostimulation therapy at its most effective period (P < 0.05). These findings suggest that functional connectivity determined by cortico-cortical evoked potentials may provide additional information that could help guide the optimal placement of responsive neurostimulation electrodes.

Surgical Outcomes in Post-Traumatic Temporal Lobe Epilepsy: A Systematic Review and Meta-Analysis

Epilepsy surgery provides excellent benefits in post-traumatic epilepsy of the temporal lobe (PTE-TL), but outcomes relative to non-traumatic epilepsy of the temporal lobe (NTE-TL) are less favorable. Large well-designed studies are recommended to further clarify the role of epilepsy surgery in PTE. It is unclear whether epilepsy surgery outcomes in PTE are as robust as described for drug resistant epilepsy (DRE) in general. Prior outcome studies in PTE are limited by small numbers, lack of a control group, or both. We performed a meta-analysis of studies in temporal lobe epilepsy (TLE) to evaluate post-surgical outcomes in those with PTE-TL and compare outcomes to those with NTE-TL. PubMed, EMBASE, and Web of Science databases were queried for studies reporting epilepsy surgery outcomes separately for PTE-TL and NTE-TL. Outcomes were divided into favorable (Engel Class I) or unfavorable (Engel Class II-IV) for comparison. Meta-analyses were performed to evaluate: 1) the proportion of Class I outcomes following epilepsy surgery in PTE-TL; and 2) calculate the odds of Class I surgical outcomes in PTE-TL compared with NTE-TL. Of 3669 articles that reported surgical outcomes in epilepsy, nine studies (n = 886) were identified that reported outcomes for both PTE-TL (n = 219) and NTE-TL (n = 667). The weighted proportion of favorable outcomes (Engel Class I) were high for both PTE-TL (70.1%, 95% CI 61.9%-78.3%) and NTE-TL (75.2%, 95% CI 69.4%-80.2%). Patients with PTE-TL were at greater risk of unfavorable (Engel Class II-IV) outcomes (relative risk 1.36, 95% CI 1.04-1.78) compared with NTE-TL.

Efficacy and safety of a smartphone application-based treatment of ketogenic diet in pediatric refractory epilepsy

OBJECTIVE

We aimed to find predictors for smartphone application-based ketogenic diet (KD) treatment effectiveness and safety.

METHODS

The efficacy was evaluated according to the reduction in seizure frequency after the intervention of KD; safety was evaluated based on adverse effects. The ordinal logistic regression analysis was used to explore the influencing factors of efficacy.

RESULTS

The study sample included 116 males and 65 females with a median age of 2.27 years. The baseline frequency of seizure was more than five times/day in 123 children, 50.83% of them received three or more antiepileptic drugs (AEDs). Seventy-two patients' KD initiation mode was outpatient, and 73 completed the 12-month follow-up. A total of 88 (48.62%) patients had reported a reduction in seizure ≥50%. Compared with 12 months, those who had received KD therapy for only 3 (P = 0.009) and 6 months (P = 0.005) were more likely to show negative outcomes. Outpatient initiation had better outcomes (P = 0.029) than inpatient initiation. For the number of AEDs applied, patients on two AEDs were more likely to achieve better outcomes (P = 0.001). Adverse events had been noted among 77 patients; BMI Z-score at KD initiation was associated with adverse effects (P = 0.003).

SIGNIFICANCE

Our study suggested that outpatient initiation and long-term treatment of KD should be encouraged.

PLAIN LANGUAGE SUMMARY

Our research shows that the KD is a helpful treatment for children with refractory epilepsy, reducing seizures by more than 50% in nearly half of the cases, with some experiencing complete seizure freedom. We used a smartphone app to improve communication between patients and their healthcare teams, resulting in a high retention, and app usage was linked to reduced adverse effects. We recommend early consideration of KD treatment for patients failing two AED, encourage outpatient initiation, and advocate for longer-term KD use.

Long-term intellectual and developmental outcomes after pediatric epilepsy surgery: A systematic review and meta-analysis

In addition to the primary aim of seizure freedom, a key secondary aim of pediatric epilepsy surgery is to stabilize and, potentially, optimize cognitive development. Although the efficacy of surgical treatment for seizure control has been established, the long-term intellectual and developmental trajectories are yet to be delineated. We conducted a systematic review and meta-analysis of studies reporting pre- and postsurgical intelligence or developmental quotients (IQ/DQ) of children with focal lesional epilepsy aged ≤18 years at epilepsy surgery and assessed at >2 years after surgery. We determined the IQ/DQ change and conducted a random-effects meta-analysis and meta-regression to assess its determinants. We included 15 studies reporting on 341 patients. The weighted mean age at surgery was 7.1 years (range = .3-13.8). The weighted mean postsurgical follow-up duration was 5.6 years (range = 2.7-12.8). The overall estimate of the mean presurgical IQ/DQ was 60 (95% confidence interval [CI] = 47-73), the postsurgical IQ/DQ was 61 (95% CI = 48-73), and the change was +.94 IQ/DQ (95% CI = -1.70 to 3.58, p = .486). Children with presurgical IQ/DQ ≥ 70 showed a tendency for higher gains than those with presurgical IQ/DQ < 70 (p = .059). Higher gains were determined by cessation of antiseizure medication (ASM; p = .041), not just seizure freedom. Our findings indicate, on average, stabilization of intellectual and developmental functioning at long-term follow-up after epilepsy surgery. Once seizure freedom has been achieved, ASM cessation enables the optimization of intellectual and developmental trajectories in affected children.

Prediction tools and risk stratification in epilepsy surgery

OBJECTIVE

This study was undertaken to conduct external validation of previously published epilepsy surgery prediction tools using a large independent multicenter dataset and to assess whether these tools can stratify patients for being operated on and for becoming free of disabling seizures (International League Against Epilepsy stage 1 and 2).

METHODS

We analyzed a dataset of 1562 patients, not used for tool development. We applied two scales: Epilepsy Surgery Grading Scale (ESGS) and Seizure Freedom Score (SFS); and two versions of Epilepsy Surgery Nomogram (ESN): the original version and the modified version, which included electroencephalographic data. For the ESNs, we used calibration curves and concordance indexes. We stratified the patients into three tiers for assessing the chances of attaining freedom from disabling seizures after surgery: high (ESGS = 1, SFS = 3-4, ESNs > 70%), moderate (ESGS = 2, SFS = 2, ESNs = 40%-70%), and low (ESGS = 2, SFS = 0-1, ESNs < 40%). We compared the three tiers as stratified by these tools, concerning the proportion of patients who were operated on, and for the proportion of patients who became free of disabling seizures.

RESULTS

The concordance indexes for the various versions of the nomograms were between .56 and .69. Both scales (ESGS, SFS) and nomograms accurately stratified the patients for becoming free of disabling seizures, with significant differences among the three tiers (p < .05). In addition, ESGS and the modified ESN accurately stratified the patients for having been offered surgery, with significant difference among the three tiers (p < .05).

SIGNIFICANCE

ESGS and the modified ESN (at thresholds of 40% and 70%) stratify patients undergoing presurgical evaluation into three tiers, with high, moderate, and low chance for favorable outcome, with significant differences between the groups concerning having surgery and becoming free of disabling seizures. Stratifying patients for epilepsy surgery has the potential to help select the optimal candidates in underprivileged areas and better allocate resources in developed countries.

Early Identification of Candidates for Epilepsy Surgery: A Multicenter, Machine Learning, Prospective Validation Study

BACKGROUND AND OBJECTIVES

Epilepsy surgery is often delayed. We previously developed machine learning (ML) models to identify candidates for resective epilepsy surgery earlier in the disease course. In this study, we report the prospective validation.

METHODS

In this multicenter, prospective, longitudinal cohort study, random forest models were validated at a pediatric epilepsy center consisting of 2 hospitals and 14 outpatient neurology clinic sites and an adult epilepsy center with 2 hospitals and 27 outpatient neurology clinic sites. The models used neurology visit notes, EEG and MRI reports, visit patterns, hospitalizations, and medication, laboratory, and procedure orders to identify candidates for surgery. The models were trained on historical data up to May 10, 2019. Patients with an ICD-10 diagnosis of epilepsy who visited from May 11, 2019, to May 10, 2020, were screened by the algorithm and assigned surgical candidacy scores. The primary outcome was area under the curve (AUC), which was calculated by comparing scores from patients who underwent epilepsy surgery before November 10, 2020, against scores from nonsurgical patients. Nonsurgical patients' charts were reviewed to determine whether patients with high scores were more likely to be missed surgical candidates. Delay to surgery was defined as the time between the first visit that a surgical candidate was identified by the algorithm and the date of the surgery.

RESULTS

A total of 5,285 pediatric and 5,782 adult patients were included to train the ML algorithms. During the study period, 41 children and 23 adults underwent resective epilepsy surgery. In the pediatric cohort, AUC was 0.91 (95% CI 0.87-0.94), positive predictive value (PPV) was 0.08 (0.05-0.10), and negative predictive value (NPV) was 1.00 (0.99-1.00). In the adult cohort, AUC was 0.91 (0.86-0.97), PPV was 0.07 (0.04-0.11), and NPV was 1.00 (0.99-1.00). The models first identified patients at a median of 2.1 years (interquartile range [IQR]: 1.2-4.9 years, maximum: 11.1 years) before their surgery and 1.3 years (IQR: 0.3-4.0 years, maximum: 10.1 years) before their presurgical evaluations.

DISCUSSION

ML algorithms can identify surgical candidates earlier in the disease course. Even at specialized epilepsy centers, there is room to shorten the time to surgery.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that a machine learning algorithm can accurately distinguish patients with epilepsy who require resective surgery from those who do not.

Patient, parent and carer perspectives surrounding expedited paediatric epilepsy surgery

OBJECTIVE

Most paediatric epilepsies with MRI visible lesions do not respond to antiseizure pharmacotherapy. Such medication resistance, which often takes years to become formally defined, is commonly required for surgical candidacy. Expedited surgical referral at lesional epilepsy diagnosis may result in better seizure, cognitive and developmental prognoses. This study explored the views of patients, parents and carers regarding epilepsy surgery, treatment priorities, and participation in a proposed expedited surgery trial.

METHODS

205 patients, parents and carers (61% UK-based, 26% North American) responded to electronic surveys from February to May 2022. Participants were recruited through social media sites, epilepsy charities and societies. Categorical choice and free-text questions were used to investigate participant perspectives, and Pearson's chi-squared test was utilised to detect meaningful differences amongst respondent subgroups.

RESULTS

Almost 90% of respondents who had experienced epilepsy surgery (either themselves or their child) reported seizure cessation or reduction. Postoperative outcome measures prioritised most frequently were seizure freedom (66%), quality of life (47%), seizure severity (30%), seizure frequency (28%) and independence (27%). Most participants support expedited surgery in suitable patients (65%), with just over half (51%) willing to participate in the proposed trial. Many participants (37%) were undecided, often due to fears surrounding neurosurgery. Subgroup perspectives were broadly similar, with more parents and caregivers favouring expedited surgery compared to patients (p = .016) and more UK-based participants willing to take part in an expedited surgery trial compared to those from North America (p = .01).

CONCLUSIONS

Patients, parents and carers are open to considering expedited surgery for lesional epilepsies and would support a trial exploring this approach. Priorities from treatment were largely similar between participant subgroups, with seizure, quality of life and neuropsychological outcomes ranked highly. Accounting for these preferences will facilitate the delivery of a trial that is patient- and caregiver-focused, enhancing feasibility, satisfaction and benefit for prospective participants.

Concordance of verbal memory and language fMRI lateralization in people with epilepsy

BACKGROUND AND PURPOSE

This work investigates verbal memory functional MRI (fMRI) versus language fMRI in terms of lateralization, and assesses the validity of performing word recognition during the functional scan.

METHODS

Thirty patients with a diagnosis of epilepsy underwent verbal memory, visuospatial memory, and language fMRI. We used word encoding, word recognition, image encoding, and image recognition memory tasks, and semantic description, reading comprehension, and listening comprehension language tasks. We used three common lateralization metrics: network spatial distribution, maximum statistical value, and laterality index (LI).

RESULTS

Lateralization of signal spatial distribution resulted in poor similarity between verbal memory and language fMRI tasks. Signal maximum lateralization showed significant (>.8) but not perfect (1) similarity. Word encoding LI showed significant correlation only with listening comprehension LI (p = .016). Word recognition LI was significantly correlated with expressive language semantic description LI (p = .024) and receptive language reading and listening comprehension LIs (p = .015 and p = .019, respectively). There was no correlation between LIs of the visuospatial tasks and LIs of the language tasks.

CONCLUSIONS

Our results support the association between language and verbal memory lateralization, optimally determined by LI quantification, and the introduction of quantitative means for language fMRI interpretation in clinical settings where verbal memory lateralization is imperative.

IQ changes after pediatric epilepsy surgery: a systematic review and meta-analysis

OBJECTIVE

This systematic review aimed to assess the intellectual outcome of children who underwent surgery for epilepsy.

METHODS

A systematic review of electronic databases was conducted on December 3, 2021, for PubMed and January 11, 2022, for Web of Science. The review was conducted according to the PRISMA guidelines. The included studies reported on intelligence quotient (IQ) or developmental quotient (DQ) before and after epilepsy surgery in children. Studies were included, if the patients had medically intractable epilepsy and if the study reported mainly on curative surgical procedures. We conducted a random-effects meta-analysis to determine the mean change of IQ/DQ.

RESULTS

Fifty-seven studies reporting on a total of 2593 patients met the inclusion criteria. The mean age at surgery was 9.2 years (± 3.44; range 2.4 months-19.81 years). Thirty-eight studies showed IQ/DQ improvement on a group level, 8 yielded stable IQ/DQ, and 19 showed deterioration. Pooled analysis revealed a significant mean gain in FSIQ of + 2.52 FSIQ points (95% CI 1.12-3.91). The pooled mean difference in DQ was + 1.47 (95% CI - 6.5 to 9.5). The pooled mean difference in IQ/DQ was 0.73 (95% CI - 4.8 to 6.2). Mean FSIQ gain was significantly higher in patients who reached seizure freedom (+ 5.58 ± 8.27) than in patients who did not (+ 0.23 ± 5.65). It was also significantly higher in patients who stopped ASM after surgery (+ 6.37 ± 3.80) than in patients who did not (+ 2.01 ± 2.41). Controlled studies showed a better outcome in the surgery group compared to the non-surgery group. There was no correlation between FSIQ change and age at surgery, epilepsy duration to surgery, and preoperative FSIQ.

SIGNIFICANCE

The present review indicates that there is a mean gain in FSIQ and DQ in children with medically intractable epilepsy after surgery. The mean gain of 2.52 FSIQ points reflects more likely sustainability of intellectual function rather than improvement after surgery. Seizure-free and ASM-free patients reach higher FSIQ gains. More research is needed to evaluate individual changes after specific surgery types and their effect on long-term follow-up.

Magnetic resonance-guided laser interstitial thermal therapy vs. open surgery for drug-resistant mesial temporal lobe epilepsy: a propensity score matched retrospective cohort study

BACKGROUND

Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) and traditional open surgery (OS) are effective and safe options for patients with drug-resistant mesial temporal lobe epilepsy (DR-mTLE). However, their superiority in seizure control and preservation of functional abilities remains unclear. This study aimed to compare the surgical outcomes of MRgLITT and OS.

MATERIALS AND METHODS

This multicenter retrospective cohort study included patients with DR-mTLE who underwent MRgLITT or OS at three centres between 2015 and 2023. The data on patient demographics, presurgical non-invasive evaluation, stereoelectroencephalography (SEEG) implantation, memory alteration, and seizure outcomes were collected. Propensity score matching (PSM) analysis was conducted for the comparison of seizure control and functional preservation between two surgical approaches.

RESULTS

Of the 244 individuals who met the study criteria, 33 underwent MRgLITT and 211 OS. The median (interquartile range) age at seizure onset was 22.0 (13.0) and 12.3 (10.0) years in the MRgLITT and OS groups, respectively. The first PSM, based on demographic and non-invasive information, resulted in 26 matched pairs for the primary analysis. There were no significant differences in memory preservation ( P = 0.95) or surgical outcomes ( P = 0.96) between the groups. The second PSM, based on demographics and SEEG implantation, yielded 32 matched pairs for the sensitivity analysis, showing similar results. Subset analysis of early and late MRgLITT cases revealed no statistically significant differences in the proportion of patients with memory decline ( P = 0.42) or seizure control ( P = 1.00). Patients who underwent SEEG implantation were 96% less likely to achieve seizure freedom after MRgLITT ( P = 0.02).

CONCLUSION

Minimally invasive MRgLITT is associated with memory preservation and seizure control, similar to traditional OS. MRgLITT is effective and safe for DR-mTLE and is relevant for future prospective randomized trials on dominant-side mTLE, providing practical implications for guiding neurosurgeons in the selection of surgical approaches.

Long-term seizure and developmental outcomes of epilepsy surgery in children under 3 years old: A single-center study of 113 patients

AIMS

To investigate the clinical characteristics, surgical strategy, developmental and seizure outcomes, and predictors of surgical outcome in children with drug-resistant epilepsy (DRE) under 3 years old.

METHODS

One hundred thirteen consecutive children younger than 3 years of age with DRE underwent curative surgical treatment after multidisciplinary preoperative evaluation using the strategy developed in the pediatric epilepsy center of Peking University First Hospital (PKFHPEC) between 2014 and 2018. These patients were selected for retrospective study. The relevant clinical data were collected and analyzed. The surgical prognoses were classified using the Engel classification, and the developmental assessment results were collected. Statistical analysis of the clinical data was performed to analyze the predictors of seizure outcomes and their correlation with developmental outcomes.

RESULTS

All the patients were followed up for more than 3 years, and 98 (86.7%) patients had no seizure recurrence. One year after surgery, the seizure-free rate was 86.7%, which was as high as that at the last follow-up. Cortical dysplasia was the most frequent etiology of DRE in this cohort, accounting for 77.0%. According to the Engel classification, acute postoperative seizure (APOS; p < 0.001) was a predictor of seizure recurrence. No deaths occurred. No unpredicted long-term severe complications occurred except for one ventricular peritoneal shunt. The patients' neurodevelopmental statuses were improved after successful surgery, while the scores of the pre- and postoperative developmental assessments were closely correlated.

CONCLUSIONS

For children who are younger than 3 years old and have DRE and structural abnormalities, early curative treatment can lead to long-term good seizure outcomes and a low complication rate. The development of appropriate strategies for both presurgical evaluation and resection is crucial for the success of surgery.

Epilepsy Surgery for Cognitive Improvement in Epileptic Encephalopathy

Epileptic encephalopathies are defined by the presence of frequent epileptiform activity that causes neurodevelopmental slowing or regression. Here, we review evidence that epilepsy surgery improves neurodevelopment in children with epileptic encephalopathies. We describe an example patient with epileptic encephalopathy without drug refractory seizures, who underwent successful diagnostic and therapeutic surgeries. In patients with epileptic encephalopathy, cognitive improvement alone is a sufficient indication to recommend surgical intervention in experienced centers.

Pediatric Neurostimulation and Practice Evolution

Since the late nineteenth century, the prevailing view of epilepsy surgery has been to identify a seizure focus in a medically refractory patient and eradicate it. Sadly, only a select number of the many who suffer from uncontrolled seizures benefit from this approach. With the development of safe, efficient stereotactic methods and targeted surgical therapies that can affect deep structures and modulate broad networks in diverse disorders, epilepsy surgery in children has undergone a paradigmatic evolutionary change. With modern diagnostic techniques such as stereo electroencephalography combined with closed loop neuromodulatory systems, pediatric epilepsy surgery can reach a much broader population of underserved patients.

Epilepsy monitoring unit practices and safety among NAEC epilepsy centers: A census survey

OBJECTIVE

An epilepsy monitoring unit (EMU) is a specialized unit designed for capturing and characterizing seizures and other paroxysmal events with continuous video electroencephalography (vEEG). Nearly 260 epilepsy centers in the United States are accredited by the National Association of Epilepsy Centers (NAEC) based on adherence to specific clinical standards to improve epilepsy care, safety, and quality. This study examines EMU staffing, safety practices, and reported outcomes.

METHOD

We analyzed NAEC annual report data and results from a supplemental survey specific to EMU practices reported in 2019 from 341 pediatric or adult center directors. Data on staffing, resources, safety practices and complications were collated with epilepsy center characteristics. We summarized using frequency (percentage) for categorical variables and median (inter-quartile range) for continuous variables. We used chi-square or Fisher's exact tests to compare staff responsibilities.

RESULTS

The supplemental survey response rate was 100%. Spell classification (39%) and phase 1 testing (28%) were the most common goals of the 91,069 reported admissions. The goal ratio of EEG technologist to beds of 1:4 was the most common during the day (68%) and off-hours (43%). Compared to residents and fellows, advanced practice providers served more roles in the EMU at level 3 or pediatric-only centers. Status epilepticus (SE) was the most common reported complication (1.6% of admissions), while cardiac arrest occurred in 0.1% of admissions.

SIGNIFICANCE

EMU staffing and safety practices vary across US epilepsy centers. Reported complications in EMUs are rare but could be further reduced, such as with more effective treatment or prevention of SE. These findings have potential implications for improving EMU safety and quality care.

Who are the Better Candidates for Epilepsy Surgery?

The resective epilepsy surgery can be the effective procedure to get seizure-free outcome in these drug resistant epilepsy (DRE) patients. Class I evidence firmly establishes the superiority of epilepsy surgery over medical treatments in both seizure control and quality of life for DRE patients. For the effective identification of optimal surgical candidates, it's essential to understand the prognostic factors of epilepsy surgery based on the surgical methods employed. Established positive prognostic indicators for temporal resection include the presence of hippocampal sclerosis on magnetic resonance imaging (MRI), focal lesions on MRI, unilateral temporal spikes, concordant ictal electroencephalography (EEG), and a history of prolonged febrile convulsion. Potential negative predictors encompass preoperative secondary generalized tonic-clonic seizures, a normal MRI, postoperative EEG spikes, and age at the time of surgery. For neocortical epilepsy, the prognostic factors identified through multivariate analysis were the presence of a discrete lesion, localized hypometabolism on Fluorodeoxyglucose positron emission tomography (FDG-PET), and localized ictal EEG. A significant correlation was found between achieving a seizure-free outcome in no visible lesion on MRI (MR-negative) epilepsy patients and having concordance in two or more presurgical evaluations, specifically in interictal EEG, ictal EEG, FDG-PET, and ictal single-photon emission computed tomography. There was a marked improvement in the seizure-free outcome in MR-negative temporal lobe epilepsy (TLE) by the application of this strategy. The better surgical candidates for epilepsy surgery are the followings: patients displaying a discrete lesion on MRI with concordant video-EEG monitoring (VEM) results, patients diagnosed with unilateral hippocampal sclerosis who have concordant VEM results, patients with unilateral hippocampal sclerosis but discordant VEM results, patients with focal cortical dysplasia and concordant VEM results, and patients diagnosed with MR-negative TLE who exhibit two or more consistent results from presurgical evaluations.

Surgical Treatment of Epilepsy with Bilateral MRI Abnormalities

OBJECTIVE

To investigate the surgical outcomes of patients with drug-resistant epilepsy and bilateral brain magnetic resonance imaging (MRI) abnormalities who had undergone various epilepsy surgeries.

METHODS

Patients with drug-resistant epilepsy and bilateral brain abnormalities on MRI who underwent epilepsy surgery at the Severance Children's Hospital between October 2003 and December 2021 were included. The age of seizure onset was 18 years or younger. Engel's classification was used to assess seizure outcomes at 1, 2, and 5 years after surgery.

RESULTS

A total of 40 patients met the inclusion criteria. The median age at surgery was 10.9 years (interquartile range [IQR] 6.9-15.1); the median interval to surgery was 7.1 years (IQR 2.7-11.5). One year after surgery, a favorable outcome of Engel class I-II was observed in 53% (21/40) of patients. At the 2- and 5-year follow-ups, 56% (20/36) and 63% (17/27) of patients showed good postoperative outcomes, respectively.

CONCLUSIONS

Approximately, half of the patients with bilateral brain MRI abnormalities achieved seizure freedom after epilepsy surgery. The existence of bilateral brain MRI abnormalities should not hinder resective epilepsy surgery.

3D4K exoscope in epilepsy surgery: a seminal experience

BACKGROUND AND OBJECTIVES

To report the progressive introduction of the exoscope (EX) from surface lesionectomy to antero-mesial temporal lobectomy (AMTL) in an epilepsy surgery practice.

METHODS

We describe a population of ten consecutive patients undergoing EX surgery, with a minimum follow-up of 6 months, that was compared to a similar population of patients referred to operative microscopic surgery (OM).

RESULTS

All surgeries were performed with the use of EX or OM alone. Transient neurological complications for surgery in eloquent regions were recorded in one patient for each population. Nine and seven patients undergoing, respectively, EX and OM surgery resulted in Engel class Ia (90% vs. 70%). The mean duration of EX and OM surgery resulted in 265.5 and 237.9 min, respectively, with a mean of 308.3 and 253.3 min for AMTL cases, respectively.

CONCLUSIONS

This preliminary study revealed that ORBEYE EX can be safe and effective in different types of epilepsy surgeries. The transition from OM to EX is fast, even though it is slower for the more challenging mesial temporal structure removal. Ergonomic and operative team interaction is improved by the use of EX. Our data need to be confirmed by larger studies.

Genetic testing in children enrolled in epilepsy surgery program. A real-life study

OBJECTIVE

Although genetic causes of drug-resistant focal epilepsy and selected focal malformations of cortical development (MCD) have been described, a limited number of studies comprehensively analysed genetic diagnoses in patients undergoing pre-surgical evaluation, their outcomes and the effect of genetic diagnosis on surgical strategy.

METHODS

We analysed a prospective cohort of children enrolled in epilepsy surgery program over January 2018-July 2022. The majority of patients underwent germline and/or somatic genetic testing. We searched for predictors of surgical outcome and positive result of germline genetic testing.

RESULTS

Ninety-five patients were enrolled in epilepsy surgery program and 64 underwent resective epilepsy surgery. We ascertained germline genetic diagnosis in 13/74 patients having underwent germline gene testing (pathogenic or likely pathogenic variants in CHRNA4, NPRL3, DEPDC5, FGF12, GRIA2, SZT2, STXBP1) and identified three copy number variants. Thirty-five patients underwent somatic gene testing; we detected 10 pathogenic or likely pathogenic variants in genes SLC35A2, PTEN, MTOR, DEPDC5, NPRL3. Germline genetic diagnosis was significantly associated with the diagnosis of focal epilepsy with unknown seizure onset.

SIGNIFICANCE

Germline and somatic gene testing can ascertain a definite genetic diagnosis in a significant subgroup of patients in epilepsy surgery programs. Diagnosis of focal genetic epilepsy may tip the scales against the decision to proceed with invasive EEG study or surgical resection; however, selected patients with genetic focal epilepsies associated with MCD may benefit from resective epilepsy surgery and therefore, a genetic diagnosis does not disqualify patients from presurgical evaluation and epilepsy surgery.

Revisiting the concept of drug-resistant epilepsy: A TASK1 report of the ILAE/AES Joint Translational Task Force

Despite progress in the development of anti-seizure medications (ASMs), one third of people with epilepsy have drug-resistant epilepsy (DRE). The working definition of DRE, proposed by the International League Against Epilepsy (ILAE) in 2010, helped identify individuals who might benefit from presurgical evaluation early on. As the incidence of DRE remains high, the TASK1 workgroup on DRE of the ILAE/American Epilepsy Society (AES) Joint Translational Task Force discussed the heterogeneity and complexity of its presentation and mechanisms, the confounders in drawing mechanistic insights when testing treatment responses, and barriers in modeling DRE across the lifespan and translating across species. We propose that it is necessary to revisit the current definition of DRE, in order to transform the preclinical and clinical research of mechanisms and biomarkers, to identify novel, effective, precise, pharmacologic treatments, allowing for earlier recognition of drug resistance and individualized therapies.

The Utility of Responsive Neurostimulation for the Treatment of Pediatric Drug-Resistant Epilepsy

Drug-resistant epilepsy (DRE) has a strongly negative impact on quality of life, as well as the development of pediatric patients. Surgical treatments have evolved over time, including more invasive craniotomies for resection or disconnection. More recently, neuromodulation techniques have been employed as a less invasive option for patients. Responsive neurostimulation (RNS) is the first closed-loop technology that allows for both treatment and device data collection, which allows for an internal assessment of the efficacy of treatment. This novel technology has been approved in adults and has been used off label in pediatrics. This review seeks to describe this technology, its history, and future directions.

Referral odyssey plot to visualize causes of surgical delay in mesial temporal lobe epilepsy with hippocampal sclerosis

The "odyssey plot" was used to visualize referral delays in epilepsy surgery. Participants were 36 patients (19 males; 13-67 years, median 27 years) with mesial temporal lobe epilepsy with hippocampal sclerosis (HS) who underwent resection surgery. The "referral odyssey plot" included five clinical episodes: seizure onset (T1), first visits to a non-epileptologist (T2) and to an epileptologist (T3), first admission to our epilepsy monitoring unit (EMU) (T4), and resection surgery (T5). For each patient, we identified the first seizure type: the physician who first diagnosed focal aware seizure (FAS), focal impaired awareness seizure (FIAS), focal to bilateral tonic-clonic seizure (FBTCS), and radiologically suspected HS. Within the overall delay (T1-T5, median 18 years; interquartile range [IQR] 14), non-epileptologist's delay (T2-T3, 11.5 years; IQR 12.25) was far (p < 0.0001) longer than patient's (T1-T2, 0 year; IQR 2.25), epileptologist's (T3-T4, 1 year; IQR 4), or after-EMU delay (T4-T5, 1 year; IQR 1). FAS onset cases had significantly longer T1-T2 (N = 5, median 7 years; IQR 6) than FIAS (N = 22, 0 year; IQR 1, p < 0.005) or FBTCS onset cases (N = 9, 0 year; IQR 0, p < 0.001). FAS was correctly diagnosed first by non-epileptologists in 17.9%, by out-patient epileptologists in 35.7%, and at the EMU in 46.4%. FIAS was correctly diagnosed first by non-epileptologists in 94.4% and by out-patient epileptologists in 5.6%. Non-epileptologists diagnosed FBTCS in all cases. HS was diagnosed by non-epileptologists in 13.9%, by out-patient epileptologists in 47.2%, and at the EMU in 38.9%. Early referral to epileptologists is most critical for early surgery. Early utilization of the EMU is highly recommended because FAS is often overlooked by outpatient epileptologists. The odyssey plot will be useful to improve the healthcare system for other types of epilepsy.

Comparing vagus nerve stimulation and resective surgery outcomes in patients with co-occurring autism and epilepsy to patients with epilepsy alone: A population-based study

Autism and epilepsy commonly co-occur. Understanding trends in healthcare utilization and in-hospital outcomes amongst patients with autism and epilepsy can help optimize care and reduce costs. We compared hospital outcomes amongst patients with autism and epilepsy to those with epilepsy alone undergoing vagus nerve stimulation (VNS) and resective/disconnective surgery. Differences in discharge status, in-hospital mortality, mean length of stay (LOS), cost and surgical/medical complications were examined. Elective surgical admissions amongst patients with epilepsy alone and co-occurring autism and epilepsy were identified in the 2003-14 National Inpatient Sample (NIS) using previously validated ICD-9-CM case definitions. One patient with co-occurring epilepsy and autism was matched to three epilepsy patients for age, sex and (1) VNS and (2) resective/disconnective surgery. Multinomial logistic regressions were performed to examine the outcomes of interest. Data were collected on: (1) VNS-52 (mean age: 12.79 ± 1.03; 19.27% female) hospital admissions in persons with comorbid autism and epilepsy, 156 (mean age: 12.84 ± 0.71; 19.31% female) matched controls with epilepsy alone; (2) resective/disconnective surgery-113 (mean age: 12.99 ± 0.84; 24.55% female) with comorbid autism and epilepsy, 339 (mean age: 13.37 ± 0.68; 23.86% female) matched controls with epilepsy alone. Compared to patients with epilepsy alone, patients with autism and epilepsy who underwent either surgery showed no differences for in-hospital mortality, discharge status, mean LOS, hospitalization cost, and surgical/medical complications. Our study shows the feasibility and safety of epilepsy VNS and resective surgery in those with ASD do not differ with those with epilepsy alone, contrary to the prevalent safety concerns of epilepsy surgery in patients with ASD.

Repurposing Artificial Intelligence Tools for Disease Modeling: Case Study of Face Recognition Deficits in Neurodegenerative Diseases

Face recognition deficits occur in diseases such as prosopagnosia, autism, Alzheimer's disease, and dementias. The objective of this study was to evaluate whether degrading the architecture of artificial intelligence (AI) face recognition algorithms can model deficits in diseases. Two established face recognition models, convolutional-classification neural network (C-CNN) and Siamese network (SN), were trained on the FEI faces data set (~ 14 images/person for 200 persons). The trained networks were perturbed by reducing weights (weakening) and node count (lesioning) to emulate brain tissue dysfunction and lesions, respectively. Accuracy assessments were used as surrogates for face recognition deficits. The findings were compared with clinical outcomes from the Alzheimer's Disease Neuroimaging Initiative (ADNI) data set. Face recognition accuracy decreased gradually for weakening factors less than 0.55 for C-CNN, and 0.85 for SN. Rapid accuracy loss occurred at higher values. C-CNN accuracy was similarly affected by weakening any convolutional layer whereas SN accuracy was more sensitive to weakening of the first convolutional layer. SN accuracy declined gradually with a rapid drop when nearly all nodes were lesioned. C-CNN accuracy declined rapidly when as few as 10% of nodes were lesioned. CNN and SN were more sensitive to lesioning of the first convolutional layer. Overall, SN was more robust than C-CNN, and the findings from SN experiments were concordant with ADNI results. As predicted from modeling, brain network failure quotient was related to key clinical outcome measures for cognition and functioning. Perturbation of AI networks is a promising method for modeling disease progression effects on complex cognitive outcomes.

Increasing challenges to trial recruitment and conduct over time

OBJECTIVE

This study was undertaken to evaluate how the challenges in the recruitment and retention of participants in clinical trials for focal onset epilepsy have changed over time.

METHODS

In this systematic analysis of randomized clinical trials of adjunct antiseizure medications for medication-resistant focal onset epilepsy, we evaluated how the numbers of participants, sites, and countries have changed since the first such trial in 1990. We also evaluated the proportion of participants who completed each trial phase and their reasons for early trial exit. We analyzed these trends using mixed effects generalized linear models accounting for the influence of the number of trial sites and trial-specific variability.

RESULTS

The number of participants per site has steadily decreased over decades, with recent trials recruiting fewer than five participants per site (reduction by .16 participants/site/year, p < .0001). Fewer participants also progressed from recruitment to randomization over time (odds ratio = .94/year, p = .014). Concurrently, there has been an increase in the placebo response over time (increase in median percent reduction of .4%/year, p = .02; odds ratio of increase in 50% responder rate of 1.03/year, p = .02), which was not directly associated with the number of sites per trial (p > .20).

SIGNIFICANCE

This historical analysis highlights the increasing challenges with participant recruitment and retention, as well as increasing placebo response. It serves as a call to action to change clinical trial design to address these challenges.

Characteristics of ictal thalamic EEG in pediatric-onset neocortical focal epilepsy

OBJECTIVE

To characterize ictal EEG change in the centromedian (CM) and anterior nucleus (AN) of the thalamus, using stereoelectroencephalography (SEEG) recordings.

METHODS

Forty habitual seizures were analyzed in nine patients with pediatric-onset neocortical drug-resistant epilepsy who underwent SEEG (age 2-25 y) with thalamic coverage. Both visual and quantitative analysis was used to evaluate ictal EEG signal in the cortex and thalamus. The amplitude and cortico-thalamic latencies of broadband frequencies at ictal onset were measured.

RESULTS

Visual analysis demonstrated consistent detection of ictal EEG changes in both the CM nucleus and AN nucleus with latency to thalamic ictal EEG changes of less than 400 ms in 95% of seizures, with low-voltage fast activity being the most common ictal pattern. Quantitative broadband amplitude analysis showed consistent power changes across the frequency bands, corresponding to ictal EEG onset, while while ictal EEG latency was variable from -18.0 seconds to 13.2 seconds. There was no significant difference between detection of CM and AN ictal activity on visual or amplitude analysis. Four patients with subsequent thalamic responsive neurostimulation (RNS) demonstrated ictal EEG changes consistent with SEEG findings.

CONCLUSIONS

Ictal EEG changes were consistently seen at the CM and AN of the thalamus during neocortical seizures.

SIGNIFICANCE

It may be feasible to use a closed-loop system in the thalamus to detect and modulate seizure activity for neocortical epilepsy.

Drug-resistant epilepsy: Definition, pathophysiology, and management

There are currently >51 million people with epilepsy (PWE) in the world and every year >4.9 million people develop new-onset epilepsy. The cornerstone of treatment in PWE is drug therapy with antiseizure medications (ASMs). However, about one-third of PWE do not achieve seizure control and do not respond well to drug therapy despite the use of appropriate ASMs [drug-resistant epilepsy (DRE)]. The aims of the current narrative review are to discuss the definition of DRE, explain the biological underpinnings and clinical biomarkers of this condition, and finally to suggest practical management strategies to tackle this issue appropriately, in a concise manner.

Pediatric epilepsy surgery from 2000 to 2018: Changes in referral and surgical volumes, patient characteristics, genetic testing, and postsurgical outcomes

OBJECTIVE

Neurosurgery is a safe and effective form of treatment for select children with drug-resistant epilepsy. Still, there is concern that it remains underutilized, and that seizure freedom rates have not improved over time. We investigated referral and surgical practices, patient characteristics, and postoperative outcomes over the past two decades.

METHODS

We performed a retrospective cohort study of children referred for epilepsy surgery at a tertiary center between 2000 and 2018. We extracted information from medical records and analyzed temporal trends using regression analyses.

RESULTS

A total of 1443 children were evaluated for surgery. Of these, 859 (402 females) underwent surgical resection or disconnection at a median age of 8.5 years (interquartile range [IQR] = 4.6-13.4). Excluding palliative procedures, 67% of patients were seizure-free and 15% were on no antiseizure medication (ASM) at 1-year follow-up. There was an annual increase in the number of referrals (7%, 95% confidence interval [CI] = 5.3-8.6; p < .001) and surgeries (4% [95% CI = 2.9-5.6], p < .001) over time. Duration of epilepsy and total number of different ASMs trialed from epilepsy onset to surgery were, however, unchanged, and continued to exceed guidelines. Seizure freedom rates were also unchanged overall but showed improvement (odds ratio [OR] 1.09, 95% CI = 1.01-1.18; p = .027) after adjustment for an observed increase in complex cases. Children who underwent surgery more recently were more likely to be off ASMs postoperatively (OR 1.04, 95% CI = 1.01-1.08; p = .013). There was a 17% annual increase (95% CI = 8.4-28.4, p < .001) in children identified to have a genetic cause of epilepsy, which was associated with poor outcome.

SIGNIFICANCE

Children with drug-resistant epilepsy continue to be put forward for surgery late, despite national and international guidelines urging prompt referral. Seizure freedom rates have improved over the past decades, but only after adjustment for a concurrent increase in complex cases. Finally, genetic testing in epilepsy surgery patients has expanded considerably over time and shows promise in identifying patients in whom surgery is less likely to be successful.

How are they doing as adults? Psychosocial and socioeconomic outcomes 11-30 years after pediatric epilepsy surgery

OBJECTIVE

Pediatric epilepsy surgery yields cure from epilepsy or complete seizure control with continued medication in many patients early in life. This study aimed to evaluate the long-term (>10 years) psychosocial and socioeconomic outcomes of pediatric epilepsy surgery and examine the role of comorbid disability, type of surgery, seizure freedom, and age at surgery.

METHODS

A novel ad hoc parent/patient questionnaire was used to assess educational and occupational attainment, marital/familial status, mobility, and other outcomes in patients who underwent unilobar or multilobar surgery for drug-refractory epilepsy during their childhood. The questionnaire also captured information on comorbid disability.

RESULTS

Of the 353 eligible patients, 203 could still be contacted and 101 of these (50%) returned appropriately filled-in questionnaires (follow-up intervals: 11-30 [mean: 19.6] years). The cure from epilepsy rate was 53%. Type of surgery was strongly confounded by comorbid disability. Patients with comorbid disabilities had significantly lower rates of regular school degrees, gainful employment, marriage, and driving license (N = 29; 12%, 4%, 0%, 3%) compared with non-disabled patients (N = 69; 89%, 80%, 43%, and 67%, respectively). Patients achieved lower school degrees than their siblings and parents. Non-disabled seizure-free patients had better employment and mobility outcomes compared with non-seizure-free patients. Age at surgery (<10 vs. ≥10 years of age) did not have any effect on any outcome in patients with preschool seizure onset.

SIGNIFICANCE

Pediatric epilepsy surgery can lead to permanent relief from epilepsy in many patients, but comorbid disability strongly impacts adult life achievement. In non-disabled patients, favorable outcomes in academic, occupational, marital, and mobility domains were achieved, approaching respective rates in the German population. Complete seizure freedom had additional positive effects on employment and mobility in this group. However, in case of chronic comorbid disability the overall life prospects may be limited despite favorable seizure outcomes.

SEEG-based reevaluation of epileptogenic networks and the predictive role for reoperation in MTLE patients with surgical failure

OBJECTIVE

Approximately 20%-30% of mesial temporal lobe epilepsy (MTLE) patients got unfavorable seizure control after surgery, and there was a discrepancy about the reasons for the surgical failure. The functional connectivity (FC) patterns obtained from stereo-electroencephalography (SEEG) reveal information about the dynamics of the epileptic brain and the added value of extracting information that was not identifiable in the SEEG data using FC analysis. This study aims to find out the patterns of the potential epileptogenic network of failure patients and the electrophysiological predictors of reoperation.

METHODS

From January 2012 to December 2019, the MTLE patients with surgical failure were reviewed, and all patients underwent SEEG-guided reoperation. The epileptogenic network was quantified by calculating FC indicators, including phase slope index (PSI), mutual information (MI) strength, imaginary coherence (icoh), and Granger causality.

RESULTS

Ten patients with 13 seizures were included in the analysis, and 7 of them achieved a favorable outcome after the SEEG-guided reoperation. The surgical zone (SZ) with a favorable prognosis showed greater outward information flow than the non-SZ, whereas the SZ with an unfavorable prognosis showed greater inward information flow. The recurrent patients with favorable prognosis had strong connectivity between the posterior hippocampus, temporal neocortex, and insula, whereas the patients with unfavorable prognosis showed strong functional connectivity between the insula and temporal-parietal-occipital junction. The power spectrum of patients with favorable prognosis was significantly lower than that of patients with unfavorable prognosis, especially showing a more oscillation power of low frequency.

SIGNIFICANCE

The SEEG-guided reoperation could achieve favorable seizure control outcomes for recurrent patients. The FCs were a potential indicator to help construct the temporal epileptic network and predictor for the reoperative prognosis in the recurrent patients.

Outcomes of resective surgery in pediatric patients with drug-resistant epilepsy: A single-center study from the Eastern Mediterranean Region

OBJECTIVE

Epilepsy surgery is widely accepted as an effective therapeutic option for carefully selected patients with drug-resistant epilepsy (DRE). There is limited data on the outcome of epilepsy surgery, especially in pediatric patients from the Eastern Mediterranean region. Hence, we performed a retrospective study examining the outcomes of resective surgery in 53 pediatric patients with focal DRE.

METHODS

Patients with focal DRE who had undergone epilepsy surgery were included in the present study. All patients underwent a comprehensive presurgical evaluation. Postoperative seizure outcomes were classified using the Engel Epilepsy Surgery Outcome Scale.

RESULTS

After surgery, 33 patients (62.2%) were Class I according to the Engel classification of surgical outcomes; eight patients (15.0%) were Class II, 11 (20.7%) were Class III, and one (1.8%) was Class IV. The relationships of presurgical, surgical, and postsurgical clinical variables to seizure outcomes were compared. Older age at seizure onset, older age at the time of surgery, the presence of focal to bilateral tonic-clonic seizures, seizure duration over 2 minutes, unsuccessful treatment with three or fewer antiseizure medications, lesions confined to one lobe (as demonstrated via magnetic resonance imaging [MRI]), surgical site in the temporal lobe, and histopathology including developmental tumors were significantly linked to an Engel Class I outcome. A univariate analysis of excellent surgical outcomes showed that lateralized semiology, localized interictal and ictal electroencephalogram (EEG) discharges, lateralized single-photon emission computed tomography and positron emission tomography findings, and temporal lobe resections were significantly related to excellent seizure outcomes.

SIGNIFICANCE

The results of our study are encouraging and similar to those found in other centers around the world. Epilepsy surgery remains an underutilized treatment for children with DRE and should be offered early.