OBJECTIVE: We comprehensively characterized a large pediatric cohort with focal cortical dysplasia (FCD) type 1 to expand the phenotypic spectrum and to identify predictors of postsurgical outcomes. METHODS: We included pediatric patients with histopathological diagnosis of isolated FCD type 1 and at least 1 year of postsurgical follow-up. We systematically reanalyzed clinical, electrophysiological, and radiological features. The results of this reanalysis served as independent variables for subsequent statistical analyses of outcome predictors. RESULTS: All children (N = 31) had drug-resistant epilepsy with varying impacts on neurodevelopment and cognition (presurgical intelligence quotient [IQ]/developmental quotient scores = 32-106). Low presurgical IQ was associated with abnormal slow background electroencephalographic (EEG) activity and disrupted sleep architecture. Scalp EEG showed predominantly multiregional and often bilateral epileptiform activity. Advanced epilepsy magnetic resonance imaging (MRI) protocols identified FCD-specific features in 74.2% of patients (23/31), 17 of whom were initially evaluated as MRI-negative. In six of eight MRI-negative cases, fluorodeoxyglucose-positron emission tomography (PET) and subtraction ictal single photon emission computed tomography coregistered to MRI helped localize the dysplastic cortex. Sixteen patients (51.6%) underwent invasive EEG. By the last follow-up (median = 5 years, interquartile range = 3.3-9 years), seizure freedom was achieved in 71% of patients (22/31), including seven of eight MRI-negative patients. Antiseizure medications were reduced in 21 patients, with complete withdrawal in six. Seizure outcome was predicted by a combination of the following descriptors: age at epilepsy onset, epilepsy duration, long-term invasive EEG, and specific MRI and PET findings. SIGNIFICANCE: This study highlights the broad phenotypic spectrum of FCD type 1, which spans far beyond the narrow descriptions of previous studies. The applied multilayered presurgical approach helped localize the epileptogenic zone in many previously nonlesional cases, resulting in improved postsurgical seizure outcomes, which are more favorable than previously reported for FCD type 1 patients.
- MeSH
- Child MeSH
- Electroencephalography * methods MeSH
- Epilepsy MeSH
- Focal Cortical Dysplasia MeSH
- Cohort Studies MeSH
- Infant MeSH
- Humans MeSH
- Magnetic Resonance Imaging * MeSH
- Malformations of Cortical Development, Group I * surgery complications diagnostic imaging MeSH
- Malformations of Cortical Development surgery complications diagnostic imaging MeSH
- Adolescent MeSH
- Positron-Emission Tomography MeSH
- Child, Preschool MeSH
- Drug Resistant Epilepsy * surgery diagnostic imaging physiopathology MeSH
- Treatment Outcome MeSH
- Check Tag
- Child MeSH
- Infant MeSH
- Humans MeSH
- Adolescent MeSH
- Male MeSH
- Child, Preschool MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
Introduction. Vagal nerve stimulation (VNS) is a therapeutical option for the treatment of drug-resistant epileptic patients. The response to VNS varies from patient to patient and is difficult to predict. The proposed study is based on our previous work, identifying relative mean power in pre-implantation EEG as a reliable marker for VNS efficacy prediction in adult patients. Our study has two main tasks. Firstly, to confirm the utility of relative mean power as a feature correlating with VNS efficacy in children. The second is to validate the applicability of our prediction classifier, Pre-X-Stim, in the pediatric population. Material and Methods. We identified a group of children with drug-resistant epilepsy. We included only children in whom EEG contained photic stimulation (Task 1) or was recorded based on the defined acquisition protocol used for development Pre-X-Stim (Task 2). Relative mean powers were calculated. VNS responders and non-responders were compared based on relative mean powers' values. In the next step, we evaluate the utility of our classifier, Pre-X-Stim, in the children population. Results: We identified 57 children treated with VNS - 17 patients were recruited for the Task 1 and 7 patients for the Task 2. When focusing on relative mean powers in EEG spectra, we observed statistically significant differences in theta range. The Pre-X-Stim algorithm was able to predict VNS efficacy correctly in 6 out of 7 patients (the accuracy 83.3%, the sensitivity 75%, the specificity 100%). Conclusions. Based on our results, it seems that children and adults share a similar pattern of EEG relative mean power changes. These changes can be used for pre-implantation prediction of VNS efficacy.
- MeSH
- Child MeSH
- Electroencephalography * methods MeSH
- Epilepsy * therapy physiopathology MeSH
- Humans MeSH
- Adolescent MeSH
- Child, Preschool MeSH
- Drug Resistant Epilepsy * therapy physiopathology MeSH
- Scalp MeSH
- Vagus Nerve Stimulation * methods MeSH
- Treatment Outcome MeSH
- Check Tag
- Child MeSH
- Humans MeSH
- Adolescent MeSH
- Male MeSH
- Child, Preschool MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
Objective.Accurate localization of the epileptogenic zone (EZ) is crucial for epilepsy surgery, but the class imbalance of epileptogenic vs. non-epileptogenic electrode contacts in intracranial electroencephalography (iEEG) data poses significant challenges for automatic localization methods. This review evaluates methodologies for handling the class imbalance in EZ localization studies that use machine learning (ML).Approach.We systematically reviewed studies employing ML to localize the EZ from iEEG data, focusing on strategies for addressing class imbalance in data handling, algorithm design, and evaluation.Results.Out of 2,128 screened studies, 35 fulfilled the inclusion criteria. Across the studies, the iEEG contacts annotated as epileptogenic prior to automatic localization constituted a median of 18.34% of all contacts. However, many of these studies did not adequately address the class imbalance problem. Techniques such as data resampling and cost-sensitive learning were used to mitigate the class imbalance problem, but the chosen evaluation metrics often failed to account for it.Significance.Class imbalance significantly impacts the reliability of EZ localization models. More comprehensive management and innovative approaches are needed to enhance the robustness and clinical utility of these models. Addressing class imbalance in ML models for EZ localization will improve both the predictive performance and reliability of these models.
Úvod: Febrilné kŕče (FK) postihujú približne 2-5% detí. Podľa väčšiny guidelines je indikáciou k hospitalizácii a diagnostike podskupina komplikovaných resp. rekurentných simplexných FK. V prípade stabilného stavu u dieťaťa (nad 18 mesiacov) po simplexných FK nie je dôvod hospitalizovať ani rozširovať diagnostiku, u detí do 18 mesiacov sa odporúča observácia do vylúčenia neuroinfekcie. Cieľom bolo porovnať publikované odporúčania s realitou praxe. Materiál a metódy: Súbor tvorilo 66 detí s FK hospitalizovaných počas 12 mesiacov na Klinike detí a dorastu UPJŠ LF a DFN Košice. Pacienti boli rozdelení podľa klinického stavu a priebehu. Manažment bol porovnaný s medzinárodnými odporúčaniami s cieľom preveriť opodstatnenosť vyšetrení (elektroencefalografia, EEG) a samotnej hospitalizácie. Výsledky: V 14 prípadoch bola dôvodom prijatia opodstatnená neurologická indikácia (komplikované FK n = 5 resp. recidivujúce simplexné kŕče n = 9). V prípadoch prvovýskytu simplexného charakteru bolo v 11 prípadoch (16% z celého súboru) hospitalizované aj stabilné dieťa s nízkym rizikom komplikácií. Počas hospitalizácie bolo EEG realizované až u 75% detí (n = 39) zo skupiny prvého výskytu simplexných FK, pričom žiadne nemalo abnormálny nález. Záver: Štúdia konštatuje nadužívanie EEG vyšetrenia, ktoré v prípade jednoduchých FK nemá opodstatnenie. EEG a neuropediatrické vyšetrenie sa odporúča realizovať len v prípadoch komplikovaných a rekurentných jednoduchých FK. Dáta potvrdzujú benígny charakter FK a podčiarkujú význam nasledovania medicínskych postupov založených na dôkazoch s cieľom racionalizácie a optimalizácie zdravotnej starostlivosti. Hospitalizácia detí s nekomplikovanými FK je opodstatnená len v prípade potreby diagnostiky a liečby pridruženej komorbidity (signifikantná dehydratácia apod.), alebo ak neuroinfekciu nie je možné klinicky vylúčiť z dôvodu nízkeho veku.
Introduction: Febrile seizures (FS) cumulatively affect approximately 2-5% of children. According to most guidelines, complicated and recurrent simplex FS are indicated for hospitalization and further diagnostic workup. In the case of a stable condition in a child (over 18 months) after simple FK, there is no reason to hospitalize or extend the diagnosis, in children under 18 months observation is recommended until neuroinfection is ruled out. The aim was to compare published recommendations with the reality of practice. Material and methods: Studied sample consisted of 66 children with FS hospitalized over 12 months at the Department of Paediatrics and Adolescent Medicine of P. J. Safarik University and Children Teaching Hospital in Košice. Patients were divided according to clinical status and course. The management was compared with international recommendations in order to verify the validity of examinations (electroencephalography, EEG) and hospitalization itself. Results: In 14 cases, the reason for admission was a justified neurological indication (complicated FS n=5 or recurrent simplex convulsions n=9). In cases of first simple FS 11 cases were identified (16% of the entire set) where a stable child with a low risk of complications was also hospitalized. During hospitalization, EEG was carried out in up to 75% of children (n=39) from the subgroup of first simple FS. None of them had abnormal EEG findings. Conclusions: The study shows the overuse of the EEG examination, which is not justified in the case of simple FS. Electroencephalographic and neuropediatric examination is recommended only in cases of complicated and recurrent simple FS. The data confirm the benign nature of FS and underline the importance of following evidence-based medical practices to rationalize and optimize health care. Hospitalization of children with uncomplicated FS is justified only if diagnosis and treatment of associated comorbidity is necessary (significant dehydration, etc.) or if neuroinfection cannot be clinically excluded due to young age.
- MeSH
- Benzodiazepines pharmacology therapeutic use MeSH
- Diagnosis, Differential MeSH
- Electroencephalography methods MeSH
- Seizures, Febrile * diagnosis etiology classification complications MeSH
- Central Nervous System Infections diagnosis complications MeSH
- Infant MeSH
- Humans MeSH
- Nervous System Diseases diagnosis classification MeSH
- Child, Preschool MeSH
- Retrospective Studies MeSH
- Check Tag
- Infant MeSH
- Humans MeSH
- Child, Preschool MeSH
- Geographicals
- Slovakia MeSH
OBJECTIVE: The pre-surgical evaluation of epilepsy relies on the electrophysiological recordings of spontaneous seizures. During this period drug dose decreases increase the likelihood of seizures transitioning the brain from a low to high seizure likelihood state, so-called pro-ictal state. This study aimed to identify the dynamic brain changes characteristic of this transition from 386 ten-minute segments of intracranial EEG recordings of 29 patients with drug-refractory temporal lobe epilepsy. METHODS: We studied brain dynamics through mean phase locking value and relative power in gamma band, and autocorrelation function width. We further explored interactions with pro-ictal factors, such as rate of interictal spikes and high frequency oscillations, circadian and multi-day cycles, and clinical outcomes. RESULTS: We observed significant increases in gamma power in the epileptogenic zone, and critical slowing in both the epileptogenic zone and presumably healthy cortex. These changes were linked with increases in spike and high frequency oscillations rate. CONCLUSIONS: Brain dynamics changed on the slow time scale - from the beginning to the end of the multi-day interval - but did not change in the short-term during the pre-ictal interval, thus could reflect pro-ictal changes. SIGNIFICANCE: We highlight gamma power and critical slowing indices as markers of pro-ictal brain states, as well as their potential to track the seizure-related brain mechanisms during the presurgical evaluation of epilepsy patients.
- MeSH
- Adult MeSH
- Electroencephalography methods MeSH
- Electrocorticography methods MeSH
- Epilepsy, Temporal Lobe * physiopathology diagnosis MeSH
- Gamma Rhythm * physiology MeSH
- Middle Aged MeSH
- Humans MeSH
- Adolescent MeSH
- Young Adult MeSH
- Brain * physiopathology MeSH
- Drug Resistant Epilepsy * physiopathology MeSH
- Seizures * physiopathology MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Adolescent MeSH
- Young Adult MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
In drug-resistant focal epilepsy, planning surgical resection can involve presurgical intracranial EEG (iEEG) recordings to detect seizures and other iEEG patterns to improve postsurgical seizure outcome. We hypothesized that resection of tissue generating interictal high-frequency oscillations (HFOs, 80-500 Hz) in the iEEG predicts surgical outcome. In eight international epilepsy centres, iEEG was recorded during the presurgical evaluation of patients. The patients were of all ages, had epilepsy of all types, and underwent surgical resection of a single focus aiming at seizure freedom. In a prospective analysis, we applied a fully automated definition of HFO that was independent of the dataset. Using an observational cohort design that was blinded to postsurgical seizure outcome, we analysed HFO rates during non-rapid-eye-movement sleep. If channels had consistently high rates over multiple epochs, they were labelled the 'HFO area'. After HFO analysis, centres provided the electrode contacts located in the resected volume and the seizure outcome at follow-up ≥24 months after surgery. The study was registered at www.clinicaltrials.gov (NCT05332990). We received 160 iEEG datasets. In 146 datasets (91%), the HFO area could be defined. The patients with a completely resected HFO area were more likely to achieve seizure freedom in comparison to those without [odds ratio 2.61, 95% confidence interval (CI) 1.15-5.91, P = 0.02]. Among seizure-free patients, the HFO area was completely resected in 31 and not completely resected in 43. Among patients with recurrent seizures, the HFO area was completely resected in 14 and not completely resected in 58. When predicting seizure freedom, the negative predictive value of the HFO area (68%, CI 52-81) was higher than that for the resected volume as a predictor by itself (51%, CI 42-59, P = 4 × 10-5). The sensitivity and specificity for complete HFO area resection were 0.88 (CI 0.72-0.98) and 0.39 (CI 0.25-0.54), respectively, and the area under the curve was 0.83 (CI 0.58-0.97), indicating good predictive performance. In a blinded cohort study from independent epilepsy centres, applying a previously validated algorithm for HFO marking without the need for adjusting to new datasets allowed us to validate the clinical relevance of HFOs to plan the surgical resection.
- MeSH
- Child MeSH
- Adult MeSH
- Electroencephalography methods MeSH
- Electrocorticography * methods MeSH
- Middle Aged MeSH
- Humans MeSH
- Adolescent MeSH
- Young Adult MeSH
- Prospective Studies MeSH
- Drug Resistant Epilepsy * surgery physiopathology MeSH
- Treatment Outcome MeSH
- Seizures * surgery physiopathology diagnosis MeSH
- Check Tag
- Child MeSH
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Adolescent MeSH
- Young Adult MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Multicenter Study MeSH
- Observational Study MeSH
Epilepsy is a neurological disease characterized by epileptic seizures, which commonly manifest with pronounced frequency and amplitude changes in the EEG signal. In the case of focal seizures, initially localized pathological activity spreads from a so-called "onset zone" to a wider network of brain areas. Chimeras, defined as states of simultaneously occurring coherent and incoherent dynamics in symmetrically coupled networks are increasingly invoked for characterization of seizures. In particular, chimera-like states have been observed during the transition from a normal (asynchronous) to a seizure (synchronous) network state. However, chimeras in epilepsy have only been investigated with respect to the varying phases of oscillators. We propose a novel method to capture the characteristic pronounced changes in the recorded EEG amplitude during seizures by estimating chimera-like states directly from the signals in a frequency- and time-resolved manner. We test the method on a publicly available intracranial EEG dataset of 16 patients with focal epilepsy. We show that the proposed measure, titled Amplitude Entropy, is sensitive to the altered brain dynamics during seizure, demonstrating its significant increases during seizure as compared to before and after seizure. This finding is robust across patients, their seizures, and different frequency bands. In the future, Amplitude Entropy could serve not only as a feature for seizure detection, but also help in characterizing amplitude chimeras in other networked systems with characteristic amplitude dynamics.
- MeSH
- Adult MeSH
- Electroencephalography methods MeSH
- Entropy MeSH
- Epilepsies, Partial * physiopathology MeSH
- Humans MeSH
- Brain * physiopathology MeSH
- Seizures * physiopathology MeSH
- Check Tag
- Adult MeSH
- Humans MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
UNLABELLED: Schizophrenia is a complex disorder characterized by altered brain functional connectivity, detectable during both task and resting state conditions using different neuroimaging methods. To this day, electroencephalography (EEG) studies have reported inconsistent results, showing both hyper- and hypo-connectivity with diverse topographical distributions. Interpretation of these findings is complicated by volume-conduction effects, where local brain activity fluctuations project simultaneously to distant scalp regions (zero-phase lag), inducing spurious inter-electrode correlations. AIM: In the present study, we explored the network dynamics of schizophrenia using a novel functional connectivity metric-corrected imaginary phase locking value (ciPLV)-which is insensitive to changes in amplitude as well as interactions at zero-phase lag. This method, which is less prone to volume conduction effects, provides a more reliable estimate of sensor-space functional network connectivity in schizophrenia. METHODS: We employed a cross-sectional design, utilizing resting state EEG recordings from two adult groups: individuals diagnosed with chronic schizophrenia (n = 30) and a control group of healthy participants (n = 30), all aged between 18 and 55 years old. RESULTS: Our observations revealed that schizophrenia is characterized by a prevalence of excess theta (4-8 Hz) power localized to centroparietal electrodes. This was accompanied by significant alterations in inter- and intra-hemispheric functional network connectivity patterns, mainly between frontotemporal regions within the theta band and frontoparietal regions within beta/gamma bands. CONCLUSIONS: Our findings suggest that patients with schizophrenia demonstrate long-range electrophysiological connectivity abnormalities that are independent of spectral power (i.e., volume conduction). Overall, distinct hemispheric differences were present in frontotemporo-parietal networks in theta and beta/gamma bands. While preliminary, these alterations could be promising new candidate biomarkers of chronic schizophrenia.
- MeSH
- Chronic Disease MeSH
- Adult MeSH
- Electroencephalography * methods MeSH
- Middle Aged MeSH
- Humans MeSH
- Adolescent MeSH
- Young Adult MeSH
- Brain physiopathology diagnostic imaging MeSH
- Nerve Net physiopathology diagnostic imaging MeSH
- Rest physiology MeSH
- Cross-Sectional Studies MeSH
- Schizophrenia * physiopathology diagnostic imaging MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Adolescent MeSH
- Young Adult MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
Electroencephalography (EEG) experiments typically generate vast amounts of data due to the high sampling rates and the use of multiple electrodes to capture brain activity. Consequently, storing and transmitting these large datasets is challenging, necessitating the creation of specialized compression techniques tailored to this data type. This study proposes one such method, which at its core uses an artificial neural network (specifically a convolutional autoencoder) to learn the latent representations of modelled EEG signals to perform lossy compression, which gets further improved with lossless corrections based on the user-defined threshold for the maximum tolerable amplitude loss, resulting in a flexible near-lossless compression scheme. To test the viability of our approach, a case study was performed on the 256-channel binocular rivalry dataset, which also describes mostly data-specific statistical analyses and preprocessing steps. Compression results, evaluation metrics, and comparisons with baseline general compression methods suggest that the proposed method can achieve substantial compression results and speed, making it one of the potential research topics for follow-up studies.
- MeSH
- Adult MeSH
- Electroencephalography * methods MeSH
- Data Compression * methods MeSH
- Humans MeSH
- Neural Networks, Computer * MeSH
- Signal Processing, Computer-Assisted MeSH
- Check Tag
- Adult MeSH
- Humans MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
INTRODUCTION: Diagnostic cortical stimulation (CS) in intracranial electroencephalography (iEEG) is an established epilepsy presurgical assessment tool to delineate relevant brain functions and elicit habitual epileptic seizures. Currently, no consensus exists as to whether CS should be routinely performed in pediatric patients. A significant challenge is their limited ability to cooperate during the procedure or to describe non-observable seizure semiology features. Our goal was to identify the spectrum of CS practices in Canada, for both eloquent cortex mapping and seizure stimulation. METHODS: An online survey, answered by all 8 Canadian pediatric epilepsy centers, enquired about implantation, stimulation methods, and use of standardized protocols. A systematic literature review extracted detailed stimulation parameters. RESULTS: Most of the institutions (n = 7/8) reported performing CS during presurgical evaluation. Four institutions indicated they perform stimulation in all implanted patients for the purpose of eloquent cortex mapping and seizure stimulation. The majority of physicians had their individual approach to CS. A largely variable approach to CS, mainly in the choice of stimulation parameters (i.e., train and pulse duration), was observed, with the highest variance concerning the purpose of seizure stimulation. The literature review highlighted an overall small sample size and minimal number of publications. Even though there is a rising trend towards stereotactic iEEG implantation, more data were available on subdural EEGs. CONCLUSION: This study shows individual and sparsely validated approach to CS in pediatric epilepsy. The literature review underscores the urgent need to harmonize pediatric intracranial EEG practices. More multicenter studies are needed to identify safe stimulation thresholds and allow implementation of evidence-based guidelines.
- MeSH
- Child MeSH
- Electroencephalography methods MeSH
- Electrocorticography methods MeSH
- Epilepsy surgery physiopathology diagnosis MeSH
- Humans MeSH
- Brain Mapping * methods MeSH
- Cerebral Cortex physiopathology MeSH
- Pediatrics methods MeSH
- Surveys and Questionnaires MeSH
- Seizures * physiopathology diagnosis MeSH
- Check Tag
- Child MeSH
- Humans MeSH
- Publication type
- Journal Article MeSH
- Systematic Review MeSH
- Geographicals
- Canada MeSH
