Epileptic Focus Research Articles

Spatiotemporal Microstate Dynamics of Spike-free Scalp EEG Offer a Potential Biomarker for Refractory Temporal Lobe Epilepsy.

Refractory temporal lobe epilepsy (TLE) is one of the most frequently observed subtypes of epilepsy and endangers more than 50 million people world-wide. Although electroencephalogram (EEG) had been widely recognized as a classic tool to screen and diagnose epilepsy, for many years it heavily relied on identifying epileptic discharges and epileptogenic zone localization, which however, limits the understanding of refractory epilepsy due to the network nature of this disease. This work hypothesizes that the microstate dynamics based on resting-state scalp EEG can offer an additional network depiction of the disease and provide potential complementary evaluation tool for the TLE even without detectable epileptic discharges on EEG. We propose a novel framework for EEG microstate spatial-temporal dynamics (EEG-MiSTD) analysis based on machine learning to comprehensively model millisecond-changing whole-brain network dynamics. With only 100 seconds of resting-state EEG even without epileptic discharges, this approach successfully distinguishes TLE patients from healthy controls and is related to the lateralization of epileptic focus. Besides, microstate temporal and spatial features are found to be widely related to clinical parameters, which further demonstrate that TLE is a network disease. A preliminary exploration suggests that the spatial topography is sensitive to the following surgical outcomes. From such a new perspective, our results suggest that spatiotemporal microstate dynamics is potentially a biomarker of the disease. The developed EEG-MiSTD framework can probably be considered as a general tool to examine dynamical brain network disruption in a user-friendly way for other types of epilepsy.

ИСТОРИЯ И ЭВОЛЮЦИЯ МЕТОДОВ НЕЙРОВИЗУАЛИЗАЦИИ В ЭПИЛЕПТОЛОГИИ

The article examines history of fundamental discoveries, methods and clinical achievements in neuroimaging, their contribution to the development of diagnosing, treatment and understanding of epilepsy etiology, also as part of International League Against Epilepsy’s research. In the early stages of its development, neuroimaging had advanced rapidly in the areas of cancer detection, pneumoencephalography, pneumomiography, ventriculography, linear tomography and selective angiography. The development of epileptology was greatly influenced by the use of computed tomography and magnetic resonance imaging, which made it possible to identify pathological lesions in a large number of patients with cryptogenic epilepsy, expand the indications for surgical treatment and improve understanding of the pathogenesis of pathological processes in the brain associated with seizure activity. In recent years, functional magnetic resonance imaging, magnetic resonance spectroscopy, positron emission tomography and single-photon emission computed tomography have become the focus of attention of researchers, which revealed a huge number of different structural changes of the brain tissue, which lie at the basis of the formation of the epileptic focus and lead to the development of focal epilepsy.

VSSI-GGD: A Variation Sparse EEG Source Imaging Approach Based on Generalized Gaussian Distribution.

Electroencephalographic (EEG) source imaging (ESI) is a powerful method for studying brain functions and surgical resection of epileptic foci. However, accurately estimating the location and extent of brain sources remains challenging due to noise and background interference in EEG signals. To reconstruct extended brain sources, we propose a new ESI method called Variation Sparse Source Imaging based on Generalized Gaussian Distribution (VSSI-GGD). VSSI-GGD uses the generalized Gaussian prior as a sparse constraint on the spatial variation domain and embeds it into the Bayesian framework for source estimation. Using a variational technique, we approximate the intractable true posterior with a Gaussian density. Through convex analysis, the Bayesian inference problem is transformed entirely into a series of regularized L2p -norm ( ) optimization problems, which are efficiently solved with the ADMM algorithm. Imaging results of numerical simulations and human experimental dataset analysis reveal the superior performance of VSSI-GGD, which provides higher spatial resolution with clear boundaries compared to benchmark algorithms. VSSI-GGD can potentially serve as an effective and robust spatiotemporal EEG source imaging method. The source code of VSSI-GGD is available at https://github.com/Mashirops/VSSI-GGD.git.

Clinical features of 21 cases of drug-resistant epilepsy and the therapeutic effect of stereotactic electroencephalography guided epileptic foci resection.

To investigate the clinical characteristics of 21 patients with drug-resistant epilepsy (DRE) and evaluate the therapeutic outcome of guided resection of epileptic foci by stereotactic electroencephalography (SEEG). The clinical data of 21 patients with DRE treated in the Brain Hospital of Guangxi Zhuang Autonomous Region from April 2022 to April 2024 were retrospectively analyzed. All patients underwent multimodal imaging assessment before surgery, and the SEEG electrode implantation scheme was designed based on clinical data. The etiology was determined via SEEG. Intraoperative resection of epileptogenic foci was guided by SEEG, followed by a postoperative follow-up to evaluate the therapeutic effect. Patients' prognosis was assessed according to the Engle Seizure Control Scale, with Engel grade I indicating a good prognosis and grades II to IV indicating a poor prognosis. Logistic regression analysis was used to further explore the influencing factors of surgical prognosis. A total of 240 SEEG electrodes were implanted in 21 patients, ranging from 8 to 17 per patient, with an average of (11.43±2.77) electrodes. There were a total of 1472 contact points, ranging from 31 to 118 per patient, with an average of (70.10±21.32). The postoperative follow-up time varied from 2 to 15 months. One patient experienced memory decline. Of the 21 patients, 11 (52.38%) had a good prognosis and 10 (47.62%) had a poor prognosis. Multivariate logistic regression analysis showed that long course of disease was an independent risk factor for poor postoperative prognosis. In the treatment of drug-resistant epilepsy, multimodal imaging based SEEG can effectively detect epileptogenic foci, guiding the surgical excision safely and efficiently. This method holds promise for enhancing surgical outcomes in the treatment of DRE.

Cognitive flexibility impairment in temporal lobe epilepsy: The impact of epileptic foci lateralization on executive functions

IntroductionTemporal Lobe Epilepsy (TLE) has been associated with memory impairments, which are typically linked to hippocampal and mesial temporal cortex lesions. Considering the presence of extensive bidirectional frontotemporal connections, it can be hypothesized that executive dysfunction in TLE is modulated by the lateralization of the epileptic foci. Material and MethodsA comprehensive neuropsychological executive functions protocol was administered to 63 participants, including 42 individuals with temporal lobe epilepsy (20 with right-TLE and 22 with left-TLE) and 21 healthy controls aged 20–49. ResultsThe results indicate that TLE patients exhibit poorer executive performance compared to healthy controls in working memory (F(2,60) = 4.18, p <.01), planning (F(2,60) = 4.71, p <.05), set shifting (F(2,60) = 10.1, p <.001), phonetic verbal fluency (F(2,60) = 11.71, p <.01) and semantic verbal fluency (F(2,60) = 9.61, p <.001. No significant differences were found in cognitive inhibition. Furthermore, right-TLE patients showed lower performance than left-TLE in set shifting (F(1,61) = 6.45, p <.05), while no significant differences were observed in working memory, planning, inhibition, and verbal fluency. ConclusionsThis research emphasize the importance of considering the lateralization of the temporal lobe focus to achieve a more accurate neuropsychological characterization. The cognitive differences between left and right TLE patients highlight the need for individualized approaches in their treatment and care.

Bilateral and asymmetrical localization of language function identified by the superselective infusion of propofol in an epilepsy patient with a mild malformation of cortical development: illustrative case.

Atypical localization of language function can result in unexpected postsurgical deficits after cortical resection, but it is difficult to predict the risk in the presurgical evaluation. The authors experienced a rare case of the bilateral and independent existence of different components of language function identified by segmented evaluation of anatomical anterior and posterior language areas using the superselective infusion of propofol. A 32-year-old right-handed female presented with drug-resistant epilepsy. Comprehensive epilepsy evaluation suggested that the epileptic foci involved the whole left frontal lobe but provided less evidence of structural abnormality. To estimate the extent of functional deterioration likely to be caused by an extended left frontal lobectomy, the authors evaluated segmented cortical function in the ipsi- and contralateral hemispheres by the superselective infusion of propofol into the branches of the intracranial artery. The results revealed bilateral and asymmetrical localization of language function because the patient presented with different components of aphasia in each hemisphere. Based on the authors' assessment of her functional tolerance, an extended left frontal lobectomy was performed and resulted in neurological deficits within the anticipated range. An accurate understanding of the correlations between vascular and functional anatomy and the highly specific evaluation of language function provides more advanced presurgical assessment, allowing more tailored planning of cortical resection.

Inhibiting Inducible Nitric Oxide Synthase with 1400W Reduces Soman (GD)-Induced Ferroptosis in Long-Term Epilepsy-Associated Neuropathology: Structural and Functional Magnetic Resonance Imaging Correlations with Neurobehavior and Brain Pathology.

Organophosphate (OP) nerve agent (OPNA) intoxication leads to long-term brain dysfunctions. The ineffectiveness of current treatments for OPNA intoxication prompts a quest for the investigation of the mechanism and an alternative effective therapeutic approach. Our previous studies on 1400W, a highly selective inducible nitric oxide synthase (iNOS) inhibitor, showed improvement in epilepsy and seizure-induced brain pathology in rat models of kainate and OP intoxication. In this study, magnetic resonance imaging (MRI) modalities, behavioral outcomes, and biomarkers were comprehensively investigated for brain abnormalities following soman (GD) intoxication in a rat model. T1 and T2 MRI robustly identified pathologic microchanges in brain structures associated with GD toxicity, and 1400W suppressed those aberrant alterations. Moreover, functional network reduction was evident in the cortex, hippocampus, and thalamus after GD exposure, and 1400W rescued the losses except in the thalamus. Behavioral tests showed protection by 1400W against GD-induced memory dysfunction, which also correlated with the extent of brain pathology observed in structural and functional MRIs. GD exposure upregulated iron-laden glial cells and ferritin levels in the brain and serum, 1400W decreased ferritin levels in the epileptic foci in the brain but not in the serum. The levels of brain ferritin also correlated with MRI parameters. Further, 1400W mitigated the overproduction of nitroxidative markers after GD exposure. Overall, this study provides direct evidence for the relationships of structural and functional MRI modalities with behavioral and molecular abnormalities following GD exposure and the neuroprotective effect of an iNOS inhibitor, 1400W. SIGNIFICANT STATEMENT: Our studies demonstrate the MRI microchanges in the brain following GD toxicity, which strongly correlate with neurobehavioral performances and iron homeostasis. The inhibition of iNOS with 1400W mitigates GD-induced cognitive decline, iron dysregulation, and aberrant brain MRI findings.

Matrix metalloproteinase 9: A Representative Diagnostic Biomarker for Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis

Matrix metalloproteinase 9 is a proteolytic enzyme which is recently one of the more often studied biomarkers. Its possible use as a biomarker of neuronal damage in stroke, heart diseases, tumors, multiple sclerosis, and epilepsy is being widely indicated. In epilepsy, MMP-9 is suggested to play a role in epileptic focus formation and in the stimulation ofseizures. The increase of MMP- 9 activity in the epileptic focus was observed both in animal models and in clinical studies. MMP-9 contributes to formation of epileptic focus,for example, by remodeling ofsynapses. Its proteolytic action on the elements of blood-brain barrier and activation of chemotactic processes facilitates accumulation of inflammatory cells and induces seizures. Also, modification of glutamatergic transmission by MMP-9 is associated with seizures.

Disentanglement of Resting State Brain Networks for Localizing Epileptogenic Zone in Focal Epilepsy.

The objective of this study is to extract pathological brain networks from interictal period of E/MEG recordings to localize epileptic foci for presurgical evaluation. We proposed here a resting state E/MEG analysis framework, to disentangle brain functional networks represented by neural oscillations. By using an Embedded Hidden Markov Model, we constructed a state space for resting state recordings consisting of brain states with different spatiotemporal patterns. Functional connectivity analysis along with graph theory was applied on the extracted brain states to quantify the network features of the extracted brain states, based on which the source location of pathological states is determined. The method is evaluated by computer simulations and our simulation results revealed the proposed framework can extract brain states with high accuracy regarding both spatial and temporal profiles. We further evaluated the framework as compared with intracranial EEG defined seizure onset zone in 10 patients with drug-resistant focal epilepsy who underwent MEG recordings and were seizure free after surgical resection. The real patient data analysis showed very good localization results using the extracted pathological brain states in 6/10 patients, with localization error of about 15mm as compared to the seizure onset zone. We show that the pathological brain networks can be disentangled from the resting-state electromagnetic recording and could be identified based on the connectivity features. The framework can serve as a useful tool in extracting brain functional networks from noninvasive resting state electromagnetic recordings, and promises to offer an alternative to aid presurgical evaluation guiding intracranial EEG electrodes implantation.

Optogenetic stimulation suppresses ictal activity in a 4-aminopyridine model of epileptic activity &lt;i&gt;in vitro&lt;/i&gt;

The WHO estimates that nearly 1% of the population suffers from epilepsy. Despite advances in the development of new antiepileptic drugs, seizures cannot be completely eliminated in nearly one-third of patients. One promising approach to the treatment of epilepsy may be gene therapy. Because epileptic activity is caused by an imbalance between excitation and inhibition, researchers have focused primarily on regulating neuronal excitability. Initially, the main approaches were based on the hyperexpression of inhibitory peptides such as galanin or NPY, or the suppression of neuronal excitability by the hyperexpression of potassium channels in neurons. However, these effects should be well calculated and strictly dosed, as it is difficult to correct the expression later. If the expression is too low, the anticonvulsant effect will not be achieved, and if the expression is too high, the neuronal networks will be impaired due to strong inhibition. For this reason, methodological approaches to treatment in which the effect on the neuronal excitability in the epileptic focus can be controlled are of great interest. Optogenetic methods offer such an advantage. Optogenetics uses light to alter the excitability of specific neuronal populations and can also be used in a biofeedback paradigm in which the light source is activated only at the risk of generating seizure activity. A number of optogenetic tools have now been developed, including light-activated cationic (e.g., ChR2) and anion channels (ACR), metabotropic receptors, pumps (NpHR, Arch), and enzymes. However, the optogenetic approach has a number of technical difficulties in delivering the light source and the risk of developing an immune response to the expression of rhodopsins. This report reviews the experience of practical application of optogenetic tools in the use of 4-aminopyridine in vitro model of epileptiform activity in experiencing slices of the entorhinal cortex. We tested the efficacy of suppressing ictal activity using several variants of optogenetic stimulation: (1) activation of excitatory and inhibitory neurons (in Thy1-ChR2-YFP mice), (2) activation of inhibitory interneurons only (in PV-Cre mice after virus injection with the channelodopsin-2 gene), hyperpolarization of excitatory neurons after expression of (3) archaeodopsin or (4) a light-dependent sodium pump. We found that ictal activity was successfully suppressed when low-frequency optogenetic stimulation induced regular interictal activity. Usually, interictal activity was induced by rhythmic synchronous activation of the principal neurons of the entorhinal cortex. In other cases, the ictal activity was preserved, although its characteristics may have changed. We determined the parameters of optogenetic stimulation that were most effective in suppressing ictal activity. The availability of a wide range of gene therapy approaches for epilepsy that have demonstrated efficacy in preclinical studies suggests that clinical trials of some of these approaches will begin in the next few years.

Targeted nanotheranostics for the treatment of epilepsy through in vivo hijacking of locally activated macrophages

Epilepsy refers to a disabling neurological disorder featured by the long-term and unpredictable occurrence of seizures owing to abnormal excessive neuronal electrical activity and is closely linked to unresolved inflammation, oxidative stress, and hypoxia. The difficulty of accurate localization and targeted drug delivery to the lesion hinders the effective treatment of this disease. The locally activated inflammatory cells in the epileptogenic region offer a new opportunity for drug delivery to the lesion. In this work, CD163-positive macrophages in the epileptogenic region were first harnessed as Trojan horses after being hijacked by targeted albumin manganese dioxide nanoparticles, which effectively penetrated the brain endothelial barrier and delivered multifunctional nanomedicines to the epileptic foci. Hence, accumulative nanoparticles empowered the visualization of the epileptogenic lesion through microenvironment-responsive MR T1-weight imaging of manganese dioxide. Besides, these manganese-based nanomaterials played a pivotal role in shielding neurons from cell apoptosis mediated by oxidative stress and hypoxia. Taken together, the present study provides an up-to-date approach for integrated diagnosis and treatment of epilepsy and other hypoxia-associated inflammatory diseases. Statement of significanceThe therapeutic effects of antiepileptic drugs (AEDs) are hindered by insufficient drug accumulation in the epileptic site. Herein, we report an efficient strategy to use locally activated macrophages as carriers to deliver multifunctional nanoparticles to the brain lesion. As MR-responsive T1 contrast agents, multifunctional BMC nanoparticles can be harnessed to accurately localize the epileptogenic region with high sensitivity and specificity. Meanwhile, catalytic nanoparticles BMC can synergistically scavenge ROS, generate O2 and regulate neuroinflammation for the protection of neurons in the brain.

Cathodal HD-tDCS and attention: A study on patients with intractable left lateral frontal lobe epilepsy

ObjectiveDefects in the attentional network in patients with epilepsy are influenced by factors such as the location of epileptic foci. Examining the impact of cathodal high-definition transcranial direct current stimulation (HD-tDCS) on attention components could provide insights into potential attention-related side effects of tDCS. This study aimed to investigate the effect of cathodal HD-tDCS on interictal epileptiform discharges (IEDs), auditory/visual (A/V) attention components, and reaction time (RT) in patients with intractable focal left lateral frontal lobe epilepsy (LFLE). MethodsTo control for variations in individual epilepsy syndrome, 12 adult participants diagnosed with drug-resistant left LFLE with focal cortical IEDs on C3 underwent repeated measurements at pretest, posttest, and follow-up steps. 4 × 1 ring electrodes (cathode on C3 and four anodes on F3, P3, T3, and Cz) delivered 2 mA DC for 20 min per session for 10 consecutive days. The integrated visual and auditory continuous performance test (IVA+) assessed the A/V attention components and RT. One-way repeated-measure ANOVA was used. ResultsThe findings suggest a significant effect in reducing IEDs. The IVA+ results showed a significant improvement in auditory divided attention and visual selective and focused attention (p < 0.05). In the follow-up, these changes demonstrated lasting efficacy. A/V speed scales increased (p < 0.05), showing a significant decrease in reaction time. ConclusionsCathodal HD-tDCS significantly reduced IEDs and improved the components of auditory divided attention, visual focused attention, and visual selective attention, with a reduction in patient reaction time. A significant lasting, side-effect-free positive effect was observed for up to one month after the intervention.

Diffusion spectrum imaging based semi-automatic optic radiation tractography for vision preservation in SEEG-guided radiofrequency thermocoagulation

ObjectiveTo assess the efficacy and safety of stereoelectroencephalography (SEEG)-guided radiofrequency thermocoagulation (RFTC), using diffusion spectrum imaging (DSI) tractography to preoperatively delineate the optic radiation (OR) and reduce the risk of visual field defects (VFDs) where the epileptogenic zones (EZs) are located in or close to the eloquent visual areas. MethodsWe prospectively followed up twenty-four consecutive patients (12 males and 12 females) who underwent SEEG-guided RFTC in or near the OR pathway. A distance of ≥ 3.5 mm away from the OR on the targeted electrodes contacts that exhibited relevant ictal onset patterns, IEDs and EES during SEEG recordings, was required as our selection criterion prior to performing RFTC, enough to theoretically prevent VFDs. Using default tracking parameters, the optic radiation was tracked semi-automatically in DSI-studio. ResultsThere were 12 male and 12 female patients ranging in age from 6 to 57 years, with follow-up period ranging from 6 to 37 months. Nineteen patients responded to RFTC (R+, 79.16 %), and 5 patients did not benefit from RFTC (R-, 20.83 %). The preoperative application of DSI semi-automatic based OR tractography was successful in the protection of the OR in all 24 patients. Three patients experienced a neurologic deficit following RFTC, and five patients had a partial quadrant visual field deficit prior to surgery that did not worsen, and none of the remaining nineteen patients had a quadrant visual field deficit. ConclusionOur study validates the safety and efficacy of SEEG-RFTC as a viable therapeutic approach for epileptic foci situated in or adjacent to the visual eloquent regions. We demonstrate that DSI-based tractography offers superior precision in delineating the OR compared to DTI. We establish that implementing a criterion of a minimum distance of ≥ 3.5 mm in radius from the OR on the targeted electrode contacts prior to conducting RFTC can effectively mitigate the risk of VFDs.

Epileptic focus localization using transfer learning on multi-modal EEG

The standard treatments for epilepsy are drug therapy and surgical resection. However, around 1/3 of patients with intractable epilepsy are drug-resistant, requiring surgical resection of the epileptic focus. To address the issue of drug-resistant epileptic focus localization, we have proposed a transfer learning method on multi-modal EEG (iEEG and sEEG). A 10-fold cross-validation approach was applied to validate the performance of the pre-trained model on the Bern-Barcelona and Bonn datasets, achieving accuracy rates of 94.50 and 97.50%, respectively. The experimental results have demonstrated that the pre-trained model outperforms the competitive state-of-the-art baselines in terms of accuracy, sensitivity, and negative predictive value. Furthermore, we fine-tuned our pre-trained model using the epilepsy dataset from Chongqing Medical University and tested it using the leave-one-out cross-validation method, obtaining an impressive average accuracy of 90.15%. This method shows significant feature differences between epileptic and non-epileptic channels. By extracting data features using neural networks, accurate classification of epileptic and non-epileptic channels can be achieved. Therefore, the superior performance of the model has demonstrated that the proposed method is highly effective for localizing epileptic focus and can aid physicians in clinical localization diagnosis.

RelB mediated by GSK3β/IκBα as a potential therapeutic target in pilocarpine seizure model rats and drug-resistant epilepsy patients

BackgroundDrug-resistant epilepsy (DRE) affects more than 20 million people worldwide. DRE patients do not respond to anti-seizure medications. Shifting from anti-seizure to anti-epileptic and disease-modifying therapy will be an important aim for future research. The canonical nuclear factor kappa B (NF-κB) signaling pathway plays a pivotal role in epilepsy and neuroinflammation. However, the expression and regulation of RelB, which can be activated via both canonical and non-canonical NF-κB signaling, are obscure in epilepsy. To clarify the expression and localization of RelB in the DRE phenotype and to determine the proteins related to RelB regulation, we conducted the following studies. MethodsQuantitative PCR was performed to detect the transcription of RELB in pilocarpine-induced epileptic rats. Western blotting was used to determine the abundance of RelB and proteins related to RelB regulation in brain tissue from both epilepsy model rats and DRE patients and in liposaccharide-induced HT22 cells. Immunofluorescence staining and immunohistochemistry were used to locate RelB in brain sections from DRE patients. ELISA was used to determine inflammatory cytokines secreted by HT22 cells into the culture medium. ResultsRELB transcription and expression were increased in the hippocampus and cortex of epileptic rats during the acute and latent phases and in epileptic foci of patients with temporal lobe epilepsy. Additionally, RelB levels were mainly increased in epileptic rat neurons and accumulated in the nuclei of hippocampal neurons. Further research demonstrated increased GSK3β phosphorylation at the Ser9 inhibitory site and decreased IκBα levels, which contributed to RelB accumulation in hippocampal neurons after seizure and in liposaccharide-stimulated HT22 cells. ConclusionsThis study is the first to demonstrate that RelB is widely distributed and increased in epileptogenic foci neurons in epileptic phenotypes. These results indicate that RelB may play roles in DRE and is mediated by GSK3β and IκBα, providing a new target for anti-epileptic and disease-modifying therapy.

Transcranial dipole localization and decoding study based on ultrasonic phased array for acoustoelectric brain imaging

Objective. Neuroimaging is one of the effective tools to understand the functional activities of the brain, but traditional non-invasive neuroimaging techniques are difficult to combine both high temporal and spatial resolution to satisfy clinical needs. Acoustoelectric brain imaging (ABI) can combine the millimeter spatial resolution advantage of focused ultrasound with the millisecond temporal resolution advantage of electroencephalogram signals. Approach. In this study, we first explored the transcranial modulated acoustic field distribution based on ABI, and further localized and decoded single and double dipoles signals. Main results. The results show that the simulation-guided acoustic field modulation results are significantly better than those of self-focusing, which can realize precise modulation focusing of intracranial target focusing. The single dipole transcranial localization error is less than 0.4 mm and the decoding accuracy is greater than 0.93. The double dipoles transcranial localization error is less than 0.2 mm and the decoding accuracy is greater than 0.89. Significance. This study enables precise focusing of transcranial acoustic field modulation, high-precision localization of source signals and decoding of their waveforms, which provides a technical method for ABI in localizing evoked excitatory neuron areas and epileptic focus.

The Agreement Between Long-Term Monitoring by Electroencephalography and Magnetic Resonance Imaging in Paediatric Seizure

Background: Demonstration of high agreement between structural abnormalities identified on magnetic resonance imaging (MRI) and physiologic abnormalities identified on electroencephalography (EEG) could benefit the assessment of epileptic focus in childhood seizures. Objectives: The present study aimed to assess the agreement between abnormal findings on brain MRI and long-term monitoring (LTM) by EEG as the standard protocol in children with abnormal focal epileptic discharges in LTM. Methods: This cross-sectional study was performed on 95 children who suffered from seizures with evidence of focal epileptic discharges in LTM who were referred to the Children's Medical Center in 2017. All patients were also concurrently evaluated by MRI. All MRIs were evaluated twice, before and after receiving the EEG results. Results: In this study, 59 out of 95 patients with abnormal LTM had concurrently abnormal MRI findings. The diagnostic agreement between the MRI and LTM in discovering abnormal findings was found to be high (86.4%) with a kappa correlation coefficient equal to 0.79. Conclusions: About two-thirds of patients with abnormal LTM findings had concurrent abnormal MRI features with high agreement between the two. Thus, MRI and EEG can be valuable in predicting epileptic focus in drug-resistant patients who need surgery.

Electroencephalography-functional magnetic resonance imaging for clinical evaluation in focal epilepsy.

We aimed to evaluate the contribution of simultaneous recording of electroencephalography-functional magnetic resonance imaging (EEG-fMRI) in the diagnosis of epilepsy syndrome, localization of the epileptogenic zone (EZ), and decision-making regarding surgical treatment. We performed a retrospective study to evaluate patients with focal epilepsy who underwent EEG-fMRI. Two evaluators assessed epilepsy syndrome, presumed focus, and surgical candidacy and defined confidence levels. They assessed these clinical characteristics first without EEG-fMRI and then including EEG-fMRI to assess how the results of EEG-fMRI changed the evaluations. We also determined how the clinical evaluation was affected by the concordance level between the blood oxygen level-dependent (BOLD) response and the presumed focus location, and by the confidence level of the BOLD response itself based on the t-value of the primary and secondary clusters. Fifty-one scans from 48 patients were included. The BOLD map affected 66.7% of the evaluations by altering evaluation items (epilepsy syndrome, presumed focus, or surgical candidacy) or their confidence levels. EEG-fMRI results increased the confidence levels of epilepsy syndrome, presumed focus, or surgical candidacy in 47.1% of patients but reduced clinical confidence in these features in 11.8%. More specifically, the confidence levels increased for epilepsy syndrome in 28.5%, identification of presumed focus in 33.9%, and determination of surgical candidacy in 29.4%. The BOLD signal confidence level, whether high or low, did not influence these clinical factors. Previous studies have emphasized the utility of EEG-fMRI for the localization of the epileptogenic zone. This study demonstrated the potential of EEG-fMRI to influence clinical confidence when determining epilepsy syndrome, the presumed epileptic focus, and surgical candidacy.

Analysis of neural fragility in epileptic zone based on stereoelectroencephalography

There are some limitations in the localization of epileptogenic zone commonly used by human eyes to identify abnormal discharges of intracranial electroencephalography in epilepsy. However, at present, the accuracy of the localization of epileptogenic zone by extracting intracranial electroencephalography features needs to be further improved. As a new method using dynamic network model, neural fragility has potential application value in the localization of epileptogenic zone. In this paper, the neural fragility analysis method was used to analyze the stereoelectroencephalography signals of 35 seizures in 20 patients, and then the epileptogenic zone electrodes were classified using the random forest model, and the classification results were compared with the time-frequency characteristics of six different frequency bands extracted by short-time Fourier transform. The results showed that the area under curve (AUC) of epileptic focus electrodes based on time-frequency analysis was 0.870 (delta) to 0.956 (high gamma), and its classification accuracy increased with the increase of frequency band, while the AUC by using neural fragility could reach 0.957. After fusing the neural fragility and the time-frequency characteristics of the γ and high γ band, the AUC could be further increased to 0.969, which was improved on the original basis. This paper verifies the effectiveness of neural fragility in identifying epileptogenic zone, and provides a theoretical reference for its further clinical application.

Rapid eye movement sleep affects interictal epileptic activity differently in mesiotemporal and neocortical areas.

Rapid eye movement (REM) sleep reduces the rate and extent of interictal epileptiform discharges (IEDs). Breakthrough epileptic activity during REM sleep is therefore thought to best localize the seizure-onset zone (SOZ). We utilized polysomnography combined with direct cortical recordings to investigate the influences of anatomical locations and the time of night on the suppressive effect of REM sleep on IEDs. Forty consecutive patients with drug-resistant focal epilepsy underwent combined polysomnography and stereo-electroencephalography during presurgical evaluation. Ten-minute interictal epochs were selected 2 h prior to sleep onset (wakefulness), and from the first and second half of the night during non-REM (NREM) sleep and REM sleep. IEDs were detected automatically across all channels. Anatomic localization, time of night, and channel type (within or outside the SOZ) were tested as modulating factors. Relative to wakefulness, there was a suppression of IEDs by REM sleep in neocortical regions (median=-27.6%), while mesiotemporal regions showed an increase in IEDs (19.1%) (p=0.01; d=0.39). This effect was reversed when comparing the regional suppression of IEDs by REM sleep relative to NREM sleep (-35.1% in neocortical; -58.7% in mesiotemporal) (p<0.001; d=0.39). Across all patients, no clinically relevant novel IED regions were observed in REM sleep versus NREM or wakefulness based on our predetermined thresholds (4 IEDs/min in REM, 0 IEDs/min in NREM and W). Finally, there was a reduction in IEDs in late (NREM: 1.08/min; REM: 0.61/min) compared to early sleep (NREM: 1.22/min; REM: 0.69/min) for both NREM (p<0.001; d=0.21) and REM (p=0.04; d=0.14). Our results demonstrate a spatiotemporal effect of IED suppression by REM sleep relative to wakefulness in neocortical, but not mesiotemporal regions, and in late versus early sleep. This suggests the importance of considering sleep stage interactions and the potential influences of anatomical locations when using IEDs to define the epileptic focus.