Lallas, Matt

Abstract Objective Invasive presurgical evaluation plays a key role in pediatric epilepsy surgery, particularly in magnetic resonance imaging (MRI)‐negative cases, by guiding resective, disconnective, or ablative procedures. This International League Against Epilepsy (ILAE) Pediatric Epilepsy Surgery Taskforce study provides an updated global overview of current invasive evaluation practices. Methods Group‐level data were collected from 61 epilepsy surgery programs (49 pediatric‐only) in 29 countries across six continents. Included were children and adolescents who underwent presurgical evaluation and epilepsy surgery in 2023. The study was designed to enable comparison with the similar ILAE survey conducted in 2004. Results A total of 2427 patients were included. Invasive evaluations were performed in 21.1% of cases, most frequently in North America (33.7%, higher than Europe: 18.0%, p = .003). Among invasive cases, 32.3% had no detectable MRI abnormalities. The main indication for invasive evaluation was seizure onset localization (88.1%), followed by motor or sensory mapping (17.2%) and language mapping (14.2%). Stereoelectroencephalography (SEEG) was the predominant technique (19.8% overall, 93.6% of invasive cases), more common in North America (30.0%, p = .021) and less common in South America (7.4%, p < .001). Subdural electrodes were used in only 3.2% of invasive cases, and combined depth and subdural approaches in 3.2%. SEEG‐guided radiofrequency thermocoagulation (RF‐TC) was performed in 40.9% of SEEG cases, most commonly in Asia (63.8%). In 16.2% of invasive evaluations, patients did not proceed to resection, disconnection, or ablation, with the highest rate in Europe (28.5%). Significance This global survey provides the first broad overview of invasive evaluation practices in pediatric epilepsy surgery across participating centers worldwide. It highlights the widespread adoption of SEEG, declining use of subdural electrodes, and increasing application of SEEG‐guided RF‐TC. The high proportion of MRI‐negative cases and the considerable proportion of patients not proceeding to resection, disconnection, or ablation underscore the complexity of contemporary surgical candidates and the need for further refinement of selection strategies.

Abstract Objective This study was undertaken to evaluate the safety and effectiveness of responsive thalamic stimulation as adjunctive therapy for drug‐resistant idiopathic generalized epilepsy (IGE) with generalized tonic–clonic seizures (GTCSs). Methods NAUTILUS is a prospective, multicenter, single‐blind, randomized sham‐controlled pivotal trial. Patients were ≥12 years of age with drug‐resistant IGE and ≥2 GTCSs over a 3‐month baseline. Bilateral depth leads were targeted to the centromedian thalamus. One month later, patients were randomized to Active (responsive stimulation, n = 44) or Sham (no stimulation, n = 43). The effectiveness evaluation period (EEP) began 3 months postimplant through 1 year. After a second GTCS in the EEP, patients transitioned to open‐label active stimulation. The primary safety endpoint was the serious adverse device‐related event (SADE) rate at 84 days postimplant. The primary effectiveness endpoint was time‐to‐second‐GTCS during the EEP. Additional endpoints included median percent change in days with any generalized seizure, GTCS frequency, and responder rate (RR). Results Eighty‐seven patients were implanted across 23 US centers. The SADE rate was significantly below the performance goal (6.9%, p < .0001), with no adverse effects on cognition, mood, or sleep. The prespecified primary effectiveness endpoint was not significant. However, a post hoc mixed‐effects model considering all EEP days demonstrated greater GTCS reduction in the originally randomized Active group (61%) compared to patients originally randomized to Sham (49%, p = .030). Eighteen‐month outcomes included 76.8% median GTCS reduction, 62.5% RR, 40% GTCS‐free at that timepoint, and 77.8% median reduction in days with any generalized seizure. More than 90% of patients and 86% of physicians reported improvement on Global Impression of Change scales. Significance NAUTILUS is the first randomized controlled neuromodulation trial in IGE. Responsive thalamic stimulation provided a clinically meaningful and durable reduction in seizures with an acceptable safety profile, offering a much‐needed option for drug‐resistant IGE.

Abstract Objective Pediatric epilepsy surgery is well established, but contemporary global data on referral and presurgical evaluation practices are lacking. This International League Against Epilepsy (ILAE) Pediatric Epilepsy Surgery Task Force study provides an updated overview of current trends and regional differences. Methods Group‐level data were collected from 61 epilepsy surgery programs (49 pediatric‐only) across 29 countries and six continents, identified through ILAE networks, and included all children and adolescents treated in 2023 who underwent presurgical evaluation/epilepsy surgery. Results Group‐level data were available for 2427 patients. Mean age at surgery was 9.1 ± 4.9 years; mean epilepsy duration was 5.3. At surgery, 3.2% were <1 year old (highest in Oceania: 5.1%), and 6.1% were nonpharmacoresistant (highest in Europe: 15.0%). Prior neurosurgery was reported in 14.2% (highest in North America: 28.8%), including 8.0% resections (6.1% for epilepsy, 1.5% for tumors; highest in Oceania: 16.5%), 2.3% disconnections (1.3% corpus callosotomy; highest in South America: 4.7%), and 4.2% neuromodulation (3.7% vagal nerve stimulation, .2% responsive neurostimulation, one deep brain stimulation; highest in North America: 12.2%). Developmental and epileptic encephalopathies (DEEs) at surgery included Lennox–Gastaut syndrome (7.4%), infantile epileptic spasms syndrome (5.1%), and DEE with spike–wave activation in sleep (1.5%). Presurgical investigations included fluorodeoxyglucose positron emission tomography (52.6%; highest in Oceania: 79.7%), genetic testing (46.8%; highest in Asia: 54.3%), magnetic resonance imaging (MRI) postprocessing (32.4%; highest in South America: 53.0%), functional MRI (fMRI; 15.2%; highest in North America: 40.3%), magnetoencephalography (11.9%; highest in North America: 39.3%), single photon emission computed tomography (9.6%; highest in North America: 22.2%), high‐density electroencephalography (EEG; 1.9%; highest in Europe: 4.7%), source localization (1.6%; highest in Oceania: 7.6%), Wada test (1.2%; highest in North America: 3.5%), and EEG‐fMRI (.5%; highest in Europe: 1.1%). Significance Despite some early surgeries, including in infancy and before pharmacoresistance, mean epilepsy duration before surgery remains >5 years. Reoperations are common, with resection more frequent than neuromodulation. Genetic testing in nearly half of patients reflects its growing relevance, and the high rate of DEEs underscores the complexity of surgical candidates.

Abstract Objective Dravet syndrome (DS) is the prototypic developmental and epileptic encephalopathy, characterized by drug‐resistant seizures, developmental slowing, and many other morbidities. Detailed characterization of behavioral phenotypes and social–emotional skill development are limited. Methods We prospectively assessed behavioral and social–emotional problems in the ENVISION natural history study (NCT04537832) of children with DS associated with SCN1A pathogenic variants ( SCN1A + DS) enrolled at <5 years of age. Assessments every 3 months for up to 2 years included the Child Behavior Checklist (CBCL), Strengths and Difficulties Questionnaire (SDQ), Brief Infant‐Toddler Social and Emotional Assessment (BITSEA), and Vineland Adaptive Behavior Scales, 3rd Edition (VABS‐3). Results Fifty‐eight children with DS enrolled at 16 sites worldwide. Problematic behaviors—inattention, aggressive or oppositional behaviors, and withdrawn and autistic behaviors—began before age 3 years, became more evident with age, and were clinically significant in many children by age 3–4 years. CBCL Total, Externalizing, and Internalizing Problems T‐scores rose by approximately 3 points per year, and BITSEA Problem scale scores increased by 2.3 points annually ( p = .002). SDQ Hyperactivity scores worsened over time ( p = .013), whereas emotional difficulties remained stable. VABS‐3 Socialization domain scores, which were already more than 1 SD below the normative mean at baseline, decreased further, particularly in younger participants. Correlation analyses showed that poorer communication abilities were associated with increased problematic behaviors ( R = −.55 for CBCL Total Problems and VABS‐3 Communication scores). Mixed‐effects modeling identified age as the strongest predictor of worsening behavioral outcomes. Significance We found that behavioral and social–emotional problems are inherent components of DS that present in toddlerhood and worsen throughout early childhood. This highlights the need to diagnose and manage these issues early. Targeted therapy may alleviate the wide‐ranging morbidities that are intrinsic to DS, including the social–emotional and behavior problems that frequently emerge.

Abstract Objective Dravet syndrome (DS) is a developmental and epileptic encephalopathy characterized by drug‐resistant seizures and developmental slowing. Although cognitive and executive function deficits have been described, their early trajectory is not well understood. Methods The prospective ENVISION natural history study (NCT04537832) assessed cognitive, executive, and adaptive function in children younger than 5 years of age with SCN1A + DS every 6 months for up to 2 years using Bayley Scales of Infant and Toddler Development, 3rd Edition (BSID‐III), Wechsler Preschool & Primary Scale of Intelligence, 4th Edition (WPPSI‐IV), Vineland Adaptive Behavior Scales, 3rd Edition (VABS‐3), Behavior Rating Inventory of Executive Function – Preschool Version (BRIEF‐P), and Pediatric Evaluation of Disability Inventory (PEDI). Results Fifty‐eight children were enrolled, with 47% younger than age 2 years. At least 80% of children did not achieve age‐appropriate milestones. Mean BSID‐III Cognitive raw scores increased minimally, with age‐equivalent gains of only 3 months over 1.5 years. Mean Cognitive Composite scores declined significantly by Month 12 (from 81.6 to 72.2; change: –11.0, 95% confidence interval [CI]: −15.3 to −6.8), signaling a widening gap compared with neurotypical development. Executive function worsened, with mean BRIEF‐P Global Executive Composite T‐scores increasing by 3.2 points/year. For some participants, scores were 5 standard deviations (SD) above the normative mean, reflecting abilities profoundly below age expectations (bottom .00003% of the population). Adaptive functioning worsened, with mean VABS‐3 Adaptive Behavior Composite decreasing from 78.7 to 68.1 over 1.5 years (change: –9.0, 95% CI: −11.9 to −6.1) and greater decline among children <2 years at enrollment, with scores decreasing by ~15 points (1 SD). Over half of children >3 years could not remove clothing independently; and when placed on a toilet, 48% could not use it. Significance Infants and young children with SCN1A + DS show significant and progressive developmental slowing across several domains, highlighting urgent need for therapies to mitigate the devastating impact on individuals and families.

Abstract Objective Dravet syndrome (DS) is a developmental and epileptic encephalopathy characterized by high seizure burden, treatment‐resistant epilepsy, and developmental stagnation. Family members rate communication deficits among the most impactful disease manifestations. We evaluated seizure burden and language/communication development in children with DS. Methods ENVISION was a prospective, observational study evaluating children with DS associated with SCN1A pathogenic variants ( SCN1A + DS) enrolled at age ≤5 years. Seizure burden and antiseizure medications were assessed every 3 months and communication and language every 6 months with the Bayley Scales of Infant and Toddler Development 3rd edition and the parent‐reported Vineland Adaptive Behavior Scales 3rd edition. We report data from the first year of observation, including analyses stratified by age at Baseline: 0:6–2:0 years:months (Y:M; youngest), 2:1–3:6 Y:M (middle), and 3:7–5:0 Y:M (oldest). Results Between December 2020 and March 2023, 58 children with DS enrolled at 16 sites internationally. Median follow‐up was 17.5 months (range = .0–24.0), with 54 of 58 (93.1%) followed for at least 6 months and 51 of 58 (87.9%) for 12 months. Monthly countable seizure frequency (MCSF) increased with age (median [minimum–maximum] = 1.0 in the youngest [1.0–70.0] and middle [1.0–242.0] age groups and 4.5 [.0–2647.0] in the oldest age group), and remained high, despite use of currently approved antiseizure medications. Language/communication delays were observed early, and developmental stagnation occurred after age 2 years with both instruments. In predictive modeling, chronologic age was the only significant covariate of seizure frequency (effect size = .52, p = .024). MCSF, number of antiseizure medications, age at first seizure, and convulsive status epilepticus were not predictors of language/communication raw scores. Significance In infants and young children with SCN1A + DS, language/communication delay and stagnation were independent of seizure burden. Our findings emphasize that the optimal therapeutic window to prevent language/communication delay is before 3 years of age.