Trajectories of parent well-being in children with drug-resistant epilepsy.

OBJECTIVE: This longitudinal cohort study aimed to identify trajectories of parent well-being over the first 2 years after their child's evaluation for candidacy for epilepsy surgery, and to identify the baseline clinical and demographic characteristics associated with these trajectories. Parent well-being was based on parent depressive and anxiety symptoms and family resources (i.e., family mastery and social support). METHODS: Parents of 259 children with drug-resistant epilepsy (105 of whom eventually had surgery) were recruited from eight epilepsy centers across Canada at the time of their evaluation for epilepsy surgery candidacy. Participants were assessed at baseline and 6-month, 1-year, and 2-year follow-up. The trajectories of parents' depressive symptoms, anxiety symptoms, and family resources were jointly estimated using multigroup latent class growth models. RESULTS: The analyses identified three trajectories: an optimal-stable group with no/minimal depressive or anxiety symptoms, and high family resources that remained stable over time; a mild-decreasing-plateau group with mild depressive and anxiety symptoms that decreased over time then plateaued, and intermediate family resources that remained stable; and a moderate-decreasing group with moderate depressive and anxiety symptoms that decreased slightly, and low family resources that remained stable over time. Parents of children with higher health-related quality of life, fathers, and parents who had higher household income were more likely to have better trajectories of well-being. Treatment type was not associated with the trajectory groups, but parents whose children were seizure-free at the time of the last follow-up were more likely to have better trajectories (optimal-stable or mild-decreasing-plateau trajectories). SIGNIFICANCE: This study documented distinct trajectories of parent well-being, from the time of the child's evaluation for epilepsy surgery. Parents who present with anxiety and depressive symptoms and low family resources do not do well over time. They should be identified and offered supportive services early in their child's epilepsy treatment history.

Dissociable default-mode subnetworks subserve childhood attention and cognitive flexibility: Evidence from deep learning and stereotactic electroencephalography.

Cognitive flexibility encompasses the ability to efficiently shift focus and forms a critical component of goal-directed attention. The neural substrates of this process are incompletely understood in part due to difficulties in sampling the involved circuitry. We leverage stereotactic intracranial recordings to directly resolve local-field potentials from otherwise inaccessible structures to study moment-to-moment attentional activity in children with epilepsy performing a flexible attentional task. On an individual subject level, we employed deep learning to decode neural features predictive of task performance indexed by single-trial reaction time. These models were subsequently aggregated across participants to identify predictive brain regions based on AAL atlas and FIND functional network parcellations. Through this approach, we show that fluctuations in beta (12-30 Hz) and gamma (30-80 Hz) power reflective of increased top-down attentional control and local neuronal processing within relevant large-scale networks can accurately predict single-trial task performance. We next performed connectomic profiling of these highly predictive nodes to examine task-related engagement of distributed functional networks, revealing exclusive recruitment of the dorsal default mode network during shifts in attention. The identification of distinct substreams within the default mode system supports a key role for this network in cognitive flexibility and attention in children. Furthermore, convergence of our results onto consistent functional networks despite significant inter-subject variability in electrode implantations supports a broader role for deep learning applied to intracranial electrodes in the study of human attention.

Pre-Operative Predictors of Health-Related Quality of Life Two Years After Pediatric Epilepsy Surgery: A Prospective Cohort Study.

PURPOSE: Seizure freedom is an important predictor of health-related quality of life (HRQOL) after pediatric epilepsy surgery. This study aimed to identify the pre-operative predictors of HRQOL 2 years after epilepsy surgery in children with drug-resistant epilepsy. METHODS: This multicenter prospective cohort study assessed pre-operative predictors including child (demographics and clinical variables), caregiver (including caregiver depressive and anxiety symptoms) and family characteristics. HRQOL was assessed using the Quality of Life in Childhood Epilepsy Questionnaire (QOLCE)-55 pre-operatively and 2-years after surgery. Univariable linear regression analyses were done to identify significant preoperative predictors of HRQOL 2-years after surgery, followed by multivariable regression. RESULTS: Ninety-five children underwent surgery, mean age was 11.4 (SD=4.2) years, and 59 (62%) were male. Mean QOLCE scores were 57.4 (95%CI: 53.8, 61.0) pre-operatively and 65.6 (95%CI: 62.0, 69.1) after surgery. Univariable regression showed fewer anti-seizure medications (ß=-6.1 [95%CI: -11.2, -1.0], p = 0.019), older age at seizure onset (ß=1.6 [95%CI: 0.8, 2.4], p<0.001), higher pre-operative HRQOL (ß=0.7 [95%CI: 0.5, 0.8], p<0.001), higher family resources (ß=0.6 [95%CI: 0.3, 0.9], p<0.001), better family relationships (ß=1.7 [95%CI: 0.3, 3.1], p = 0.017) and lower family demands (ß=-0.9 [95%CI: -1.5, -0.4], p<0.001) were associated with higher HRQOL after surgery. Caregiver characteristics did not predict HRQOL after surgery (p>0.05). Multivariable regression showed older age at seizure onset (ß=4.6 [95%CI: 1.6, 7.6], p = 0.003) and higher pre-operative HRQOL (ß=10.2 [95%CI: 6.8, 13.6], p<0.001) were associated with higher HRQOL after surgery. CONCLUSION: This study underscores the importance of optimizing pre-operative HRQOL to maximize HRQOL outcome after pediatric epilepsy surgery.

A longitudinal cohort study of mediators of health-related quality of life after pediatric epilepsy surgery or medical treatment.

OBJECTIVES: The purpose of this longitudinal cohort study was to examine the variables that influence health-related quality of life (HRQOL) after epilepsy surgery in children. We examined whether treatment type (surgical vs medical therapy) and seizure control are related to other variables that have been shown to influence HRQOL, namely depressive symptoms in children with epilepsy or their parents, and the availability of family resources. METHODS: In total, 265 children with drug-resistant epilepsy were recruited from eight epilepsy centers across Canada at the time of their evaluation for candidacy for epilepsy surgery and were assessed at baseline, 6-month, 1-year, and 2-year follow-up. Parents completed the Quality of Life in Childhood Epilepsy Questionnaire (QOLCE-55) and measures of family resources and depression; children completed depression inventories. Causal mediation analyses using natural effect models were used to evaluate the extent to which the relationship between treatment and HRQOL was explained by seizure control, child and parent depressive symptoms, and family resources. RESULTS: Overall, 111 children underwent surgery and 154 were treated with medical therapy only. The HRQOL scores of surgical patients were 3.4 points higher (95% confidence interval [CI]: -0.2, 7.0) relative to medical patients at the 2-year follow-up after adjusting for baseline covariates, with 66% of the effect of surgery attributed to seizure control. Child or parent depressive symptoms and family resources had negligible mediation effects between treatment and HRQOL. The effect of seizure control on HRQOL was not mediated by child or parent depressive symptoms, or by family resources. SIGNIFICANCE: The findings demonstrate that seizure control is on the causal pathway between epilepsy surgery and improved HRQOL in children with drug-resistant epilepsy. However, child and parent depressive symptoms and family resources were not significant mediators. The results highlight the importance of achieving seizure control to improve HRQOL.

Trajectory of Health-Related Quality of Life After Pediatric Epilepsy Surgery.

Importance: Health-related quality of life (HRQOL) is regarded as a key outcome for evaluating treatment efficacy. However, it is uncertain how HRQOL evolves after epilepsy surgery compared with medical therapy, such as whether it continues to improve over time, improves and then remains stable, or deteriorates after a period of time. Objective: To assess trajectory of HRQOL over 2 years in children with drug-resistant epilepsy (DRE) treated with surgery compared with medical therapy. Design, Setting, and Participants: Prospective cohort study assessing HRQOL longitudinally over 2 years. Participants were children recruited from 8 epilepsy centers in Canada from 2014 to 2019 with suspected DRE aged 4 to 18 years who were evaluated for surgery. Data were analyzed from May 2014 to December 2021. Exposures: Epilepsy surgery or medical therapy. Main Outcomes and Measures: HRQOL was measured using the Quality of Life in Childhood Epilepsy Questionnaire (QOLCE)-55. HRQOL and seizure frequency were assessed at baseline, 6-month, 1-year, and 2-year follow-ups. Clinical, parent, and family characteristics were assessed at baseline. A linear mixed model was used to evaluate HRQOL over time, adjusting for baseline clinical, parent, and family characteristics. Results: There were 111 surgical and 154 medical patients (mean [SD] age at baseline was 11.0 [4.1] years; 118 [45%] were female). At baseline, HRQOL was similar among surgical and medical patients. HRQOL of surgical patients was 3.0 (95% CI, -0.7 to 6.8) points higher at 6-month, 4.9 (95% CI, 0.7 to 9.1) points higher at 1-year, and 5.1 (95% CI, 0.7 to 9.5) points higher at 2-year follow-ups compared with medical patients. Surgical patients experienced greater improvements in social functioning relative to medical patients, but not for cognitive, emotional, and physical functioning. At 2-year follow-up, 72% of surgical patients were seizure-free, compared with 33% of medical patients. Seizure-free patients reported higher HRQOL than those who were not. Conclusions and Relevance: This study provided evidence on the association between epilepsy surgery and children's HRQOL, with improvement in HRQOL occurring within the first year and remaining stable 2 years after surgery. By demonstrating that surgery improved seizure freedom and HRQOL, which has downstream effects such as better educational attainment, reduced health care resource utilization, and health care cost, these findings suggest that the high costs of surgery are justified, and that improved access to epilepsy surgery is necessary.

The Epilepsy Surgery Experience in Children With Infantile Epileptic Spasms Syndrome at a Tertiary Care Center in Canada.

Background: Infantile epileptic spasms syndrome is an epileptic encephalopathy, characterized by spasms, hypsarrhythmia, and developmental regression. Appropriately selected patients with infantile epileptic spasms syndrome may be candidates for epilepsy surgery. Methods: This is a single-center retrospective case series of children 0-18 years with a current or previous diagnosis of infantile epileptic spasms syndrome with a lesion on magnetic resonance imaging (MRI) and/or positron emission tomography scan who underwent epilepsy surgery at The Hospital for Sick Children (HSC) in Toronto, Canada. The records of 223 patients seen in the infantile epileptic spasms syndrome clinic were reviewed. Results: Nineteen patients met inclusion criteria. The etiology of infantile epileptic spasms syndrome was encephalomalacia in 6 patients (32%), malformations of cortical development in 12 patients (63%), and atypical hypoglycemic injury in 1 patient (5%). Nine patients (47%) underwent hemispherectomy, and 10 patients (53%) underwent lobectomy/lesionectomy. Three patients (16%) underwent a second epilepsy surgery. Fifteen patients (79%) were considered ILAE seizure outcome class 1 (completely seizure free; no auras) at their most recent follow-up visit. The percentage of patients who were ILAE class 1 at most recent follow-up decreased with increasing duration of epilepsy prior to surgery. Developmental outcome after surgery was improved in 14 of 19 (74%) and stable in 5 of 19 (26%) patients. Conclusions: Our study found excellent seizure freedom rates and improved developmental outcomes following epilepsy surgery in patients with a history of infantile epileptic spasms syndrome with a structural lesion detected on MRI brain. Patients who undergo surgery earlier have improved seizure freedom rates and improved developmental outcomes.

Which is more deleterious to cognitive performance? Interictal epileptiform discharges vs anti-seizure medication.

Children with epilepsy commonly have comorbid neurocognitive impairments that severely affect their psychosocial well-being, education, and future career prospects. Although the provenance of these deficits is multifactorial, the effects of interictal epileptiform discharges (IEDs) and anti-seizure medications (ASMs) are thought to be particularly severe. Although certain ASMs can be leveraged to inhibit IED occurrence, it remains unclear whether epileptiform discharges or the medications themselves are most deleterious to cognition. To examine this question, 25 children undergoing invasive monitoring for refractory focal epilepsy performed one or more sessions of a cognitive flexibility task. Electrophysiological data were recorded to detect IEDs. Between repeated sessions, prescribed ASMs were either continued or titrated to <50% of the baseline dose. Hierarchical mixed-effects modeling assessed the relationship between task reaction time (RT), IED occurrence, ASM type, and dose while controlling for seizure frequency. Both presence (ß ± SE = 49.91 ± 16.55 ms, p = .003) and number of IEDs (ß ± SE = 49.84 ± 12.51 ms, p < .001) were associated with slowed task RT. Higher dose oxcarbazepine significantly reduced IED frequency (p = .009) and improved task performance (ß ± SE = -107.43 ± 39.54 ms, p = .007). These results emphasize the neurocognitive consequences of IEDs independent of seizure effects. Furthermore, we demonstrate that inhibition of IEDs following treatment with select ASMs is associated with improved neurocognitive function.

Epilepsy disrupts hippocampal phase precision and impairs working memory.

OBJECTIVE: Working memory deficits are prevalent in childhood epilepsy. Working memory processing is thought to be supported by the phase of hippocampal neural oscillations. Disruptions in working memory have previously been linked to the occurrence of transient epileptic activity. This study aimed to resolve the associations between oscillatory neural activity, transient epileptiform events, and working memory in children with epilepsy. METHODS: Intracranial recordings were acquired from stereotactically implanted electrodes in the hippocampi, epileptogenic zones, and working memory-related networks of children with drug-resistant epilepsy during a 1-back working memory task. Interictal epileptic activity was captured using automated detectors. Hippocampal phase and interregional connectivity within working memory networks were indexed by Rayleigh Z and the phase difference derivative, respectively. Trials with and without transient epileptiform events were compared. RESULTS: Twelve children (mean age = 14.3 ± 2.8 years) with drug-resistant epilepsy were included in the study. In the absence of transient epileptic activity, significant delta and theta hippocampal phase resetting occurred in response to working memory stimulus presentation (Rayleigh z-score = 9, Rayleigh z-score = 8). Retrieval trials that were in phase with the preferred phase angle were associated with faster reaction times (p = .01, p = .03). Concurrently, delta and theta coordinated interactions between the hippocampi and working memory-related networks were enhanced (phase difference derivative [PDD] z-scores = 6-11). During retrieval trials with pre-encoding or pre-retrieval transient epileptic activity, phase resetting was attenuated (Rayleigh z-score = 5, Rayleigh z-score = 1), interregional connectivity was altered (PDD z-scores = 1-3), and reaction times were prolonged (p = .01, p = .03). SIGNIFICANCE: This work highlights the role of hippocampal phase in working memory. We observe poststimulus hippocampal phase resetting coincident with enhanced interregional connectivity. The precision of hippocampal phase predicts optimal working memory processing, and transient epileptic activity prolongs working memory processing. These findings can help guide future treatments aimed at restoring memory function in this patient population.

Interictal discharges delay target-directed eye movements and impair attentional set-shifting in children with epilepsy.

OBJECTIVE: The theory of transient cognitive impairment in epilepsy posits that lapses in attention result from ephemeral disruption of attentional circuitry by interictal events. Eye movements are intimately associated with human attention and can be monitored in real time using eye-tracking technologies. Here, we sought to characterize the associations between interictal epileptiform discharges (IEDs), gaze, and attentional behavior in children with epilepsy. METHODS: Eleven consecutive children undergoing invasive monitoring with stereotactic electrodes for localization-related epilepsy performed an attentional set-shifting task while tandem intracranial electroencephalographic signals and eye-tracking data were recorded. Using an established algorithm, IEDs were detected across all intracranial electrodes on a trial-by-trial basis. Hierarchical mixed-effects modeling was performed to delineate associations between trial reaction time (RT), eye movements, and IEDs. RESULTS: Hierarchical mixed-effects modeling revealed that both the presence of an IED (ß ± SE = 72.74 ± 24.21 ms, p = .003) and the frequency of epileptiform events (ß ± SE = 67.54 ± 17.30 ms, p < .001) were associated with prolonged RT on the attentional set-shifting task. IED occurrence at the time of stimulus presentation was associated with delays in gaze initiation toward the visual targets (p = .017). SIGNIFICANCE: The occurrence of epileptiform activity in close temporal association with stimulus presentation is associated with delays in target-directed gaze and prolonged response time, hallmarks of momentary lapses in attention. These findings provide novel insights into the mechanisms of transient impairments in children and support the use of visual tracking as a correlate of higher order attentional behavior.

ILAE classification and definition of epilepsy syndromes with onset in neonates and infants: Position statement by the ILAE Task Force on Nosology and Definitions.

The International League Against Epilepsy (ILAE) Task Force on Nosology and Definitions proposes a classification and definition of epilepsy syndromes in the neonate and infant with seizure onset up to 2 years of age. The incidence of epilepsy is high in this age group and epilepsy is frequently associated with significant comorbidities and mortality. The licensing of syndrome specific antiseizure medications following randomized controlled trials and the development of precision, gene-related therapies are two of the drivers defining the electroclinical phenotypes of syndromes with onset in infancy. The principal aim of this proposal, consistent with the 2017 ILAE Classification of the Epilepsies, is to support epilepsy diagnosis and emphasize the importance of classifying epilepsy in an individual both by syndrome and etiology. For each syndrome, we report epidemiology, clinical course, seizure types, electroencephalography (EEG), neuroimaging, genetics, and differential diagnosis. Syndromes are separated into self-limited syndromes, where there is likely to be spontaneous remission and developmental and epileptic encephalopathies, diseases where there is developmental impairment related to both the underlying etiology independent of epileptiform activity and the epileptic encephalopathy. The emerging class of etiology-specific epilepsy syndromes, where there is a specific etiology for the epilepsy that is associated with a clearly defined, relatively uniform, and distinct clinical phenotype in most affected individuals as well as consistent EEG, neuroimaging, and/or genetic correlates, is presented. The number of etiology-defined syndromes will continue to increase, and these newly described syndromes will in time be incorporated into this classification. The tables summarize mandatory features, cautionary alerts, and exclusionary features for the common syndromes. Guidance is given on the criteria for syndrome diagnosis in resource-limited regions where laboratory confirmation, including EEG, MRI, and genetic testing, might not be available.

Methodology for classification and definition of epilepsy syndromes with list of syndromes: Report of the ILAE Task Force on Nosology and Definitions.

Epilepsy syndromes have been recognized for >50 years, as distinct electroclinical phenotypes with therapeutic and prognostic implications. Nonetheless, no formally accepted International League Against Epilepsy (ILAE) classification of epilepsy syndromes has existed. The ILAE Task Force on Nosology and Definitions was established to reach consensus regarding which entities fulfilled criteria for an epilepsy syndrome and to provide definitions for each syndrome. We defined an epilepsy syndrome as "a characteristic cluster of clinical and electroencephalographic features, often supported by specific etiological findings (structural, genetic, metabolic, immune, and infectious)." The diagnosis of a syndrome in an individual with epilepsy frequently carries prognostic and treatment implications. Syndromes often have age-dependent presentations and a range of specific comorbidities. This paper describes the guiding principles and process for syndrome identification in both children and adults, and the template of clinical data included for each syndrome. We divided syndromes into typical age at onset, and further characterized them based on seizure and epilepsy types and association with developmental and/or epileptic encephalopathy or progressive neurological deterioration. Definitions for each specific syndrome are contained within the corresponding position papers.

Connectomic Profiles and Cognitive Trajectories After Epilepsy Surgery in Children.

BACKGROUND AND OBJECTIVES: Neurocognitive outcomes after surgery for temporal lobe epilepsy in childhood are variable. Postoperative changes are not directly predicted by seizure freedom, and associations between epilepsy, neuropsychological function, and developing neural networks are poorly understood. Here, we leveraged whole-brain connectomic profiling in magnetoencephalography (MEG) to retrospectively study associations between brain connectivity and neuropsychological function in children with temporal lobe epilepsy undergoing resective surgery. METHODS: Clinical and MEG data were retrospectively analyzed for children who underwent temporal lobe epilepsy surgery at the Hospital for Sick Children from 2000 to 2021. Resting-state connectomes were constructed from neuromagnetic oscillations via the weighted-phase lag index. Using a partial least-squares (PLS) approach, we assessed multidimensional associations between patient connectomes, neuropsychological scores, and clinical covariates. Bootstrap resampling statistics were performed to assess statistical significance. RESULTS: A total of 133 medical records were reviewed, and 5 PLS analyses were performed. Each PLS analysis probed a particular neuropsychological domain and the associations between its baseline and postoperative scores and the connectomic data. In each PLS analysis, a significant latent variable was identified, representing a specific percentage of the variance in the data and relating neural networks to clinical covariates, which included changes in rote verbal memory (n = 41, p = 0.01, σ2 = 0.38), narrative/verbal memory (n = 57, p = 0.00, σ2 = 0.52), visual memory (n = 51, p = 0.00, σ2 = 0.43), working memory (n = 44, p = 0.00, σ2 = 0.52), and overall intellectual function (n = 59, p = 0.00, σ2 = 0.55). Children with more diffuse, bilateral intrinsic connectivity across several frequency bands showed lower scores on all neuropsychological assessments but demonstrated a greater propensity for gains after resective surgery. DISCUSSION: Here, we report that connectomes characterized by diffuse connectivity, reminiscent of developmentally immature networks, are associated with lower preoperative cognition and postoperative cognitive improvement. These findings provide a potential means to understand neurocognitive function in children with temporal lobe epilepsy and expected changes postoperatively.

Health Care System Costs Associated With Surgery and Medical Therapy for Children With Drug-Resistant Epilepsy in Ontario.

BACKGROUND AND OBJECTIVES: Improvement in seizure control after epilepsy surgery could lead to lower health care resource use and costs, but it is uncertain whether this could offset the high costs related to surgery. This study aimed to evaluate phase-specific and cumulative long-term health care costs of surgery compared to medical therapy in children with drug-resistant epilepsy from the health care payer perspective. METHODS: Children who were evaluated for epilepsy surgery and treated with surgery or medical therapy from 2003 to 2018 at the Hospital for Sick Children in Toronto were identified from chart review and linked to their health administrative databases in Ontario, Canada. Inverse probability of treatment weighting with stabilized weights was used to balance the baseline covariates between the 2 groups. Patients were assigned to presurgery, surgery, short-term (first 2 years), intermediate-term (2-5 years), and long-term (>5 years) postsurgery care phases on the basis of treatment trajectory. Phase-specific and cumulative long-term health care costs were evaluated. Costs were converted from Canadian to US dollars year 2018 value. RESULTS: There were 372 surgical and 258 medical patients. Costs were higher in surgical than medical patients for presurgery (3 and 39 weeks), surgery, and short-term care phase, and the attributable costs of surgery per 7 patient-days were $1,602 (95% CI $1,438-$1,785), $172 (95% CI $147-$185), $19,819 (95% CI $18,822-$20,932), and $28 (95% CI $22-$32), respectively. Costs were lower in surgical patients for intermediate- and long-term care phase, and the attributable costs were -$72 (95% CI -$124 to -$35) and -$94 (95% CI -$129 to -$63), respectively. In surgical patients, costs were highest for surgery followed by presurgery care phase, with hospitalizations accounting for the highest cost component. In medical patients, costs increased gradually from presurgery to long-term care phase. Cumulative costs were higher for surgical than medical patients in the first 7 years after surgery, but from 8 years on, costs were lower for surgical patients. DISCUSSION: This study demonstrated the long-term economic benefits of epilepsy surgery compared to medical therapy for the health care system with the use of real-world data, which would justify the high costs of surgery. The results will support future economic evaluation comparing minimally invasive treatment such as laser therapy to surgery.

Surgical outcomes in children with bottom-of-sulcus dysplasia and drug-resistant epilepsy: a retrospective cohort study.

OBJECTIVE: Bottom-of-sulcus dysplasia (BOSD) is challenging to identify radiologically. The aim of this study was to explore seizure outcomes after resective surgery or MR-guided laser interstitial thermal therapy (MRgLITT) in children with BOSD. METHODS: Children with radiologically defined BOSD who underwent resective surgery or MRgLITT, with at least 1 year of follow-up were included. Clinical, radiological, neurophysiological, and histological data were extracted from medical records. Invasive video EEG (IVEEG) was used to evaluate the ictal onset zone or motor/language mapping, wherever appropriate. Histology of MRI-visible BOSD, including the overlying and adjacent cortex, was also evaluated. RESULTS: Forty-one children with BOSD underwent surgical treatment. The lesion was initially overlooked on MRI in 20 patients (48.8%). Of 34 patients who underwent IVEEG and who had available ictal data, the ictal onset zone extended beyond the MRI-visible BOSD in 23 patients (67.6%). Surgical treatment included lesionectomy (24 patients), extended lesionectomy (12 patients), lobectomy (1 patient), and ablation of BOSD (4 patients). The pathology in 37 patients who underwent resection showed focal cortical dysplasia type IIB and type IIA in 21 (53.8%) and 16 patients (41%), respectively. Seizure freedom was achieved in 32 patients (78.1%) after a mean follow-up of 4.3 years. CONCLUSIONS: Seizure outcomes after resective surgery or MRgLITT in children with BOSD were generally favorable. The authors found that the neurophysiological abnormality and pathology often extended beyond the MRI-visible BOSD.

Phase Resetting in the Anterior Cingulate Cortex Subserves Childhood Attention and Is Impaired by Epilepsy.

The neural mechanisms that underlie selective attention in children are poorly understood. By administering a set-shifting task to children with intracranial electrodes stereotactically implanted within anterior cingulate cortex (ACC) for epilepsy monitoring, we demonstrate that selective attention in a set-shifting task is dependent upon theta-band phase resetting immediately following stimulus onset and that the preferred theta phase angle is predictive of reaction time during attentional shift. We also observe selective enhancement of oscillatory coupling between the ACC and the dorsal attention network and decoupling with the default mode network during task performance. When transient focal epileptic activity occurs around the time of stimulus onset, phase resetting is impaired, connectivity changes with attentional and default mode networks are abolished, and reaction times are prolonged. The results of the present work highlight the fundamental mechanistic role of oscillatory phase in ACC in supporting attentional circuitry and present novel opportunities to remediate attention deficits in children with epilepsy.

Alterations in coordinated EEG activity precede the development of seizures in comatose children.

OBJECTIVE: We aimed to test the hypothesis that computational features of the first several minutes of EEG recording can be used to estimate the risk for development of acute seizures in comatose critically-ill children. METHODS: In a prospective cohort of 118 comatose children, we computed features of the first five minutes of artifact-free EEG recording (spectral power, inter-regional synchronization and cross-frequency coupling) and tested if these features could help identify the 25 children who went on to develop acute symptomatic seizures during the subsequent 48 hours of cEEG monitoring. RESULTS: Children who developed acute seizures demonstrated higher average spectral power, particularly in the theta frequency range, and distinct patterns of inter-regional connectivity, characterized by greater connectivity at delta and theta frequencies, but weaker connectivity at beta and low gamma frequencies. Subgroup analyses among the 97 children with the same baseline EEG background pattern (generalized slowing) yielded qualitatively and quantitatively similar results. CONCLUSIONS: These computational features could be applied to baseline EEG recordings to identify critically-ill children at high risk for acute symptomatic seizures. SIGNIFICANCE: If confirmed in independent prospective cohorts, these features would merit incorporation into a decision support system in order to optimize diagnostic and therapeutic management of seizures among comatose children.

Supplementing Extraoperative Electrocorticography With Real-Time Intraoperative Recordings Using the Same Chronically Implanted Electrodes.

BACKGROUND: The practice of intraoperative electrocorticography (iECoG) to guide resective epilepsy surgery is variable. Limitations of iECoG include variability in recordings from previously unsampled cortex, increased operative time and cost, and a lack of clear benefit to surgical decision-making. OBJECTIVE: To describe a simple technique to supplement extraoperative intracranial recordings with real-time iECoG using the same chronically implanted electrodes that overcome some of these limitations. METHODS: We describe the technical procedure, intraoperative findings, and outcomes of 7 consecutive children undergoing 2-stage resective epilepsy surgery with invasive subdural grid monitoring between January 2017 and December 2019. All children underwent placement of subdural grids, strips, and depth electrodes. Planned neocortical resection was based on extraoperative mapping of ictal and interictal recordings. During resection in the second stage, the same electrodes were used to perform real-time iECoG. RESULTS: Real-time iECoG using this technique leads to modification of resection for 2 of the 7 children. The first was extended due to an electroencephalographic seizure from a distant electrode not part of the original resection plan. The second was restricted due to attenuation of epileptiform activity following a partial resection, thereby limiting the extent of a Rolandic resection. No infections or other adverse events were encountered. CONCLUSION: We report a simple technique to leverage chronically implanted electrodes for real-time iECoG during 2-stage resective surgery. This technique presents fewer limitations than traditional approaches and may alter intraoperative decision-making.

Brainstem Associated Somatosensory Evoked Potentials and Response to Vagus Nerve Stimulation: An Investigation of the Vagus Afferent Network.

Despite decades of clinical usage, selection of patients with drug resistant epilepsy who are most likely to benefit from vagus nerve stimulation (VNS) remains a challenge. The mechanism of action of VNS is dependent upon afferent brainstem circuitry, which comprises a critical component of the Vagus Afferent Network (VagAN). To evaluate the association between brainstem afferent circuitry and seizure response, we retrospectively collected intraoperative data from sub-cortical recordings of somatosensory evoked potentials (SSEP) in 7 children with focal drug resistant epilepsy who had failed epilepsy surgery and subsequently underwent VNS. Using multivariate linear regression, we demonstrate a robust negative association between SSEP amplitude (p < 0.01), and seizure reduction. There was no association between SSEP latency and seizure outcomes. Our findings provide novel insights into the mechanism of VNS and inform our understanding of the importance of brainstem afferent circuitry within the VagAN for seizure responsiveness following VNS.

Detection of high-frequency oscillations in electroencephalography: A scoping review and an adaptable open-source framework.

PURPOSE: High frequency oscillations (HFOs) are putative biomarkers of epileptogenicity. These electrophysiological phenomena can be effectively detected in electroencephalography using automated methods. Nonetheless, the implementation of these methods into clinical practice remains challenging as significant variability exists between algorithms and their characterizations of HFOs. Here, we perform a scoping review of the literature pertaining to automated HFO detection methods. In addition, we propose a framework for defining and detecting HFOs based on a simplified single-stage time-frequency based detection algorithm with clinically-familiar parameters. METHODS: Several databases (OVID Medline, Web of Science, PubMed) were searched for articles presenting novel, automated HFO detection methods. Details related to the algorithm and various stages of data acquisition, pre-processing, and analysis were abstracted from included studies. RESULTS: From the 261 records screened, 57 articles presented novel, automated HFO detection methods and were included in the scoping review. These algorithms were categorized into 3 groups based on their most salient features: energy thresholding, time-frequency analysis, and data mining/machine learning. Algorithms were optimized for specific datasets and suffered from low specificity. A framework for user-constrained inputs is proposed to circumvent some of the weaknesses of highly performant detectors. CONCLUSIONS: Further efforts are required to optimize and validate existing automated HFO detection methods for clinical utility. The proposed framework may be applied to understand and standardize the variations in HFO definitions across institutions.

Longitudinal changes in emotional functioning following pediatric resective epilepsy surgery: 2-Year follow-up.

OBJECTIVE: To examine longitudinal changes and predictors of depression and anxiety 2 years following resective epilepsy surgery, compared to no surgery, in children with drug-resistant epilepsy (DRE). METHOD: This multicenter cohort study involved 128 children and adolescents with DRE (48 surgical, 80 nonsurgical; 8-18 years) who completed self-report measures of depression and anxiety at baseline and follow-up (6-month, 1-year, 2-year). Child demographic (age, sex, IQ) and seizure (age at onset, duration, frequency, site and side) variables were collected. RESULTS: Linear mixed-effects models controlling for age at enrolment found a time by treatment by seizure outcome interaction for depression. A negative linear trend across time (reduction in symptoms) was found for surgical patients, irrespective of seizure outcome. In contrast, the linear trend differed depending on seizure outcome in nonsurgical patients; a negative trend was found for those with continued seizures, whereas a positive trend (increase in symptoms) was found for those who achieved seizure freedom. Only a main effect of time was found for anxiety indicating a reduction in symptoms across patient groups. Multivariate regressions failed to find baseline predictors of depression or anxiety at 2-year follow-up in surgical patients. Older age, not baseline anxiety or depression, predicted greater symptoms of anxiety and depression at 2-year follow-up in nonsurgical patients. CONCLUSION: Children with DRE reported improvement in anxiety and depression, irrespective of whether they achieve seizure control, across the 2 years following surgery. In contrast, children with DRE who did not undergo surgery, but achieved seizure freedom, reported worsening of depressive symptoms, which may indicate difficulty adjusting to life without seizures and highlight the potential need for ongoing medical and psychosocial follow-up and support.