Drug-Resistant Epilepsy and Surgery

Prediction of Pharmacoresistance in Drug-Naïve Temporal Lobe Epilepsy Using Ictal EEGs Based on Convolutional Neural Network

Approximately 30%-40% of epilepsy patients do not respond well to adequate anti-seizure medications (ASMs), a condition known as pharmacoresistant epilepsy. The management of pharmacoresistant epilepsy remains an intractable issue in the clinic. Its early prediction is important for prevention and diagnosis. However, it still lacks effective predictors and approaches. Here, a classical model of pharmacoresistant temporal lobe epilepsy (TLE) was established to screen pharmacoresistant and pharmaco-responsive individuals by applying phenytoin to amygdaloid-kindled rats. Ictal electroencephalograms (EEGs) recorded before phenytoin treatment were analyzed. Based on ictal EEGs from pharmacoresistant and pharmaco-responsive rats, a convolutional neural network predictive model was constructed to predict pharmacoresistance, and achieved 78% prediction accuracy. We further found the ictal EEGs from pharmacoresistant rats have a lower gamma-band power, which was verified in seizure EEGs from pharmacoresistant TLE patients. Prospectively, therapies targeting the subiculum in those predicted as "pharmacoresistant" individual rats significantly reduced the subsequent occurrence of pharmacoresistance. These results demonstrate a new methodology to predict whether TLE individuals become resistant to ASMs in a classic pharmacoresistant TLE model. This may be of translational importance for the precise management of pharmacoresistant TLE.

On-demand electrically controlled perampanel delivery from a PEDOT/SNP composite for seizure control

Deep brain stimulation and closed-loop electrical stimulation are considered among the most effective techniques for treating pharmacoresistant epilepsy. However, various neuromodulation techniques and corresponding stimulation parameters have different effects on controlling epileptic seizures. To enhance the ability of stimulating electrodes to regulate nerve activity, sulfonated silica nanoparticles (SNPs) loaded with the anti-seizure medication perampanel were used as dopants in the conductive polymer PEDOT to modify the implanted neural electrode. After electrochemical deposition of PEDOT/SNP-perampanel on nickel-chromium alloy electrodes, the charge storage capacity was significantly increased, and the electrochemical impedance at 1 kHz was significantly reduced. In addition, perampanel could be released on demand by applying electrical stimulation, allowing for precise drug delivery to the brain area to reduce seizure frequency. We anticipate that this modification method will enable broader applications in neural interfaces and the treatment of neurological diseases.

Dynamical intracranial EEG functional network controllability localizes the seizure onset zone and predicts the epilepsy surgical outcome

Objective. Seizure onset zone (SOZ) localization and SOZ resection outcome prediction are critical for the surgical treatment of drug-resistant epilepsy but have mainly relied on manual inspection of intracranial electroencephalography (iEEG) monitoring data, which can be both inaccurate and time-consuming. Therefore, automating SOZ localization and surgical outcome prediction by using appropriate iEEG neural features and machine learning models has become an emerging topic. However, current channel-wise local features, graph-theoretic network features, and system-theoretic network features cannot fully capture the spatial, temporal, and neural dynamical aspects of epilepsy, hindering accurate SOZ localization and surgical outcome prediction.Approach. Here, we develop a method for computing dynamical functional network controllability from multi-channel iEEG signals, which from a control-theoretic viewpoint, has the ability to simultaneously capture the spatial, temporal, functional, and dynamical aspects of epileptic brain networks. We then apply multiple machine learning models to use iEEG functional network controllability for localizing SOZ and predicting surgical outcomes in drug-resistant epilepsy patients and compare with existing neural features. We finally combine iEEG functional network controllability with representative local, graph-theoretic, and system-theoretic features to leverage complementary information for further improving performance.Main results. We find that iEEG functional network controllability at SOZ channels is significantly higher than that of other channels. We further show that machine learning models using iEEG functional network controllability successfully localize SOZ and predict surgical outcomes, significantly outperforming existing local, graph-theoretic, and system-theoretic features. We finally demonstrate that there exists complementary information among different types of neural features and fusing them further improves performance.Significance. Our results suggest that iEEG functional network controllability is an effective feature for automatic SOZ localization and surgical outcome prediction in epilepsy treatment.

Head-to-Head comparison of [18F]FDG, [18F]FMZ, and [18F]SynVesT-1 positron emission tomography imaging in patients with drug-resistant epilepsy

PURPOSE

The loss of synaptic vesicle glycoprotein 2 A (SV2A) can lead to dysfunction of GABAergic neurons, but a direct comparison of SV2A and GABAA receptor densities in humans has not been assessed. This study evaluated SV2A and GABAA receptor abnormalities in patients with drug-resistant epilepsy (DRE) and compared the patterns to glucose hypometabolism.

METHODS

Eleven patients with DRE were retrospectively recruited and underwent PET imaging with [18F]fluorodeoxyglucose ([18F]FDG), [18F]Flumazenil (FMZ), and [18F]SynVesT-1. Visual assessments counted abnormal metabolic brain regions based on the Anatomical Automatic Labeling (AAL) atlas, while voxel-level analyses delineated the abnormal metabolic distributions. The relationship between hypo-metabolic distributions and the age of epilepsy onset was analyzed.

RESULTS

The hypometabolic regions in [18F]FDG PET, identified in the AAL atlas, was significantly broader than in [18F]FMZ (p = 0.0005) and [18F]SynVesT-1 (p = 0.0010) PET, with no statistical difference observed between [18F]FMZ and [18F]SynVesT-1 PET (p > 0.05). The voxel number in [18F]FDG PET was significantly higher than that of the [18F]FMZ and [18F]SynVesT-1 PET in both hypo-intensity area and severe hypo-intensity area. The ratio of the voxel number between these two area was higher for [18F]SynVesT-1 PET compared to [18F]FDG PET (p = 0.0195) and [18F]FMZ PET (p = 0.0237), and positively correlated with the age of epilepsy onset (r = 0.7397, p = 0.0145).

CONCLUSIONS

[18F]FMZ and [18F]SynVesT-1 PET images revealed a more restricted pattern of reduced uptake compared to [18F]FDG PET in DRE patients. The age of epilepsy onset correlated with a reduction in [18F]SynVesT-1 uptake but not in [18F]FMZ or [18F]FDG uptake.

Functional MRI study of neurovascular coupling in patients with non-lesional epilepsy

Objective

The diagnosis of patients with non-lesional epilepsy (NLE) is relatively challenging because of the absence of a clear focus on imaging, and the underlying pathological mechanism remains unclear. The neuronal activity and functional connectivity of NLE patients are significantly abnormal, and the neuronal activity of epilepsy patients is closely related to cerebral blood flow (CBF). Neurovascular coupling (NVC) offers insights into the relationship between neuronal activity and CBF. Hence, we intend to explore the alterations of NVC in NLE patients and their influences on cognitive function.

Methods

Clinical data of 24 patients with NLE (15 female; age range 19-40 years; median age 30.5 years) and 39 healthy controls (27 female; age range 19-40 years; median age 30 years) were collected, and resting-state functional magnetic resonance imaging (rs-fMRI) and 3D arterial spin labeling (ASL) were performed. The imaging indexes of amplitude of low-frequency fluctuation (ALFF) and CBF were calculated, respectively, by post-processing analysis. The differences in CBF, ALFF and CBF/ALFF ratio between the two groups were analyzed, along with correlation with clinical data of NLE patients.

Results

Compared with the healthy controls, the CBF of the right parahippocampal gyrus was significantly decreased, and the CBF/ALFF ratio of the right inferior parietal, but supramarginal and angular gyri was significantly increased in NLE patients (p < 0.001). Moreover, the CBF/ALFF ratio was positively correlated with epilepsy depression score (r = 0.546, p = 0.006).

Conclusion

NLE patients showed abnormal local NVC, which was associated with the severity of depression. The combined application of rs-fMRI and ASL can comprehensively evaluate the neuronal activity and cerebral blood perfusion in patients with NLE. The abnormal NVC is of great significance for us to explore the central mechanism of the occurrence and development of NLE.

A Revolutionary Approach for Combating Efflux Transporter-mediated Resistant Epilepsy: Advanced Drug Delivery Systems

Epilepsy is a persistent neurological condition that affects 60 million individuals globally, with recurrent spontaneous seizures affecting 80% of patients. Antiepileptic drugs (AEDs) are the main course of therapy for approximately 65% of epileptic patients, and the remaining 35% develop resistance to medication, which leads to drug-resistant epilepsy (DRE). DRE continues to be an important challenge in clinical epileptology. There are several theories that attempt to explain the neurological causes of pharmacoresistance in epilepsy. The theory that has been studied the most is the transporter hypothesis. Therefore, it is believed that upregulation of multidrug efflux transporters at the blood-brain barrier (BBB), such as P-glycoprotein (P-gp), which extrudes AEDs from their target location, is the major cause, leading to pharmacoresistance in epilepsy. The most effective strategies for managing this DRE are peripheral and central inhibition of P-gp and maintaining an effective concentration of the drug in the brain parenchyma. Presently, no medicinal product that inhibits Pgp is being used in clinical practice. In this review, several innovative and promising treatment methods, including gene therapy, intracranial injections, Pgp inhibitors, nanocarriers, and precision medicine, are discussed. The primary goal of this work is to review the P-gp transporter, its substrates, and the latest novel treatment methods for the management of DRE.

Resting-state fMRI seizure onset localization meta-analysis: comparing rs-fMRI to other modalities including surgical outcomes

Objective

Resting-state functional MRI (rs-fMRI) may localize the seizure onset zone (SOZ) for epilepsy surgery, when compared to intracranial EEG and surgical outcomes, per a prior meta-analysis. Our goals were to further characterize this agreement, by broadening the queried rs-fMRI analysis subtypes, comparative modalities, and same-modality comparisons, hypothesizing SOZ-signal strength may overcome this heterogeneity.

Methods

PubMed, Embase, Scopus, Web of Science, and Google Scholar between April 2010 and April 2020 via PRISMA guidelines for SOZ-to-established-modalities were screened. Odd ratios measured agreement between SOZ and other modalities. Fixed- and random-effects analyses evaluated heterogeneity of odd ratios, with the former evaluating differences in agreement across modalities and same-modality studies.

Results

In total, 9,550 of 14,384 were non-duplicative articles and 25 met inclusion criteria. Comparative modalities were EEG 7, surgical outcome 6, intracranial EEG 5, anatomical MRI 4, EEG-fMRI 2, and magnetoencephalography 1. Independent component analysis 9 and seed-based analysis 8 were top rs-fMRI methods. Study-level odds ratio heterogeneity in both the fixed- and random-effects analysis was significant (p < 0.001). Marked cross-modality and same-modality systematic differences in agreement between rs-fMRI and the comparator were present (p = 0.005 and p = 0.002), respectively, with surgical outcomes having higher agreement than EEG (p = 0.002) and iEEG (p = 0.007). The estimated population mean sensitivity and specificity were 0.91 and 0.09, with predicted values across studies ranging from 0.44 to 0.96 and 0.02 to 0.67, respectively.

Significance

We evaluated centrality and heterogeneity in SOZ agreement between rs-fMRI and comparative modalities using a wider variety of rs-fMRI analyzing subtypes and comparative modalities, compared to prior. Strong evidence for between-study differences in the agreement odds ratio was shown by both the fixed- and the random-effects analyses, attributed to rs-fMRI analysis variability. Agreement with rs-fMRI differed by modality type, with surgical outcomes having higher agreement than EEG and iEEG. Overall, sensitivity was high, but specificity was low, which may be attributed in part to differences between other modalities.

Bilateral pulvinar responsive neurostimulation for bilateral multifocal posteriorly dominant drug resistant epilepsy

OBJECTIVE

To describe four cases of Responsive Neurostimulation (RNS) in the bilateral pulvinar nuclei (PUL) in individuals with drug resistant epilepsy (DRE). This will show that due to widespread PUL connectivity, bilateral PUL RNS may be an option for some individuals with bilateral multifocal epilepsy.

METHODS

This study comprises two centers' experience with bilateral PUL RNS for DRE. Patients treated with bilateral PUL RNS at Westchester Medical Center (Valhalla, NY) and Corewell Health (Grand Rapids, MI) between the years 2019 and 2022 were analyzed and described. Presented here are methods for target selection, device programming, and clinical outcomes.

RESULTS

Two patients with Lennox-Gastaut phenotype (aged 13 and 21 years) with posteriorly dominant discharges were implanted with bilateral PUL electrodes. Additionally, two patients (aged 20 and 31 years) with independent left and right occipital bilateral multifocal seizure onsets were implanted with bilateral RNS devices targeting the ipsilateral PUL and ipsilateral occipital cortex. Subclinical and clinical seizures were captured by RNS electrocorticography (ECoG) in all patients. RNS implantation and treatment was well-tolerated without adverse effects in all patients. Relative to baseline, two patients had 25% and 50% reduction in disabling seizures, and two patients had 71% and 100% reduction in disabling seizures. Stimulation paradigms utilized high frequency stimulation in both Lennox-Gastaut phenotype patients. Low frequency (individualized to the terminal ictal frequencies) stimulation was effective in the two bioccipital patients.

SIGNIFICANCE

RNS with electrode placement targeting bilateral PUL is safe, and no adverse effects have been attributable to the pulvinar electrode placement. PUL responsive neurostimulation is potentially effective for patients with bilateral multifocal, posteriorly dominant DRE. Both high and low frequency responsive stimulation are treatment options. Longer follow-up will shed light on the ultimate reduction of seizure burden.

PLAIN LANGUAGE SUMMARY

We describe four cases where stimulation devices were placed in the Pulvinar area of the thalamus (central sensory area in the brain). This is very unique and different location than where these devices are typically placed. These patients all had great outcomes with marked seizure reduction, demonstrating that this placement is both safe and effective.

Cannabichromene from full-spectrum hemp extract exerts acute anti-seizure effects through allosteric activation of GABAA receptors

The approval of Epidiolex, an anti-epileptic drug containing cannabidiol (CBD) as its active component, has brought hope to patients with refractory epilepsy. However, the anti-seizure effect of full-spectrum hemp extract (HE), a CBD-enriched hemp oil, remains unclear. In this study, we investigated the anti-seizure effect of HE using drug-induced seizure models. Our findings revealed that HE significantly reduced seizure susceptibility comparable to CBD at the same doses. Moreover, we explored the pharmacokinetic properties of CBD in HE and observed improved characteristics such as faster oral absorption, enhanced brain distribution, and slower elimination. We further assessed the anti-seizure effects of the other five main non-addictive components in HE. Among these components, cannabichromene (CBC) and cannabinol (CBN) showed significant anti-seizure effects. To gain insights into the mechanisms of CBC and CBN, we investigated their allosteric modulation on the GABAA receptor. Our results revealed that CBC enhanced GABA-induced currents in both Xenopus laevis oocytes and mouse primary cortical neurons. Additionally, we identified V436 in the β2 subunit of the GABAA receptor as a critical binding site for CBC. These findings provide compelling evidence for the anti-seizure activities of HE and shed light on its underlying mechanisms. Our study provides insights into the broader therapeutic potential of hemp extracts and suggests their possible development as anti-seizure treatments.

Microglia in Microbiota-Gut-Brain Axis: A Hub in Epilepsy

There is growing concern about the role of the microbiota-gut-brain axis in neurological illnesses, and it makes sense to consider microglia as a critical component of this axis in the context of epilepsy. Microglia, which reside in the central nervous system, are dynamic guardians that monitor brain homeostasis. Microglia receive information from the gut microbiota and function as hubs that may be involved in triggering epileptic seizures. Vagus nerve bridges the communication in the axis. Essential axis signaling molecules, such as gamma-aminobutyric acid, 5-hydroxytryptamin, and short-chain fatty acids, are currently under investigation for their participation in drug-resistant epilepsy (DRE). In this review, we explain how vagus nerve connects the gut microbiota to microglia in the brain and discuss the emerging concepts derived from this interaction. Understanding microbiota-gut-brain axis in epilepsy brings hope for DRE therapies. Future treatments can focus on the modulatory effect of the axis and target microglia in solving DRE.

Alterations in serum metabolomics during the first seizure and after effective control of epilepsy

The existing diagnostic methods of epilepsy have great limitations, and more reliable and less difficult diagnostic methods are needed. We collected serum samples of adult patients with first-diagnosed epilepsy (EPs) and seizure control patients (EPRs) for non-targeted metabolomics detection and found that they were both significantly altered, with increased expression of nicotine addiction, linoleic acid metabolism, purine metabolism, and other metabolic pathways. The diagnostic model based on 4 differential metabolites achieved a diagnostic efficiency of 99.4% in the training cohort and 100% in the validation cohort. In addition, the association analysis of oral flora, serum metabolism, and clinical indicators also provided a new angle to analyze the mechanism of epilepsy. In conclusion, this study characterized the serum metabolic characteristics of EPs and EPRs and the changes before and after epilepsy control based on a large cohort, demonstrating the potential of metabolites as non-invasive diagnostic tools for epilepsy.

Peimine promotes microglial polarization to the M2 phenotype to attenuate drug-resistant epilepsy through suppressing the TLR4/NF-κB/HIF-1α signaling pathway in a rat model and in BV-2 microglia

Epilepsy is a chronic neurological disorder. Drug-resistant epilepsy (DRE) accounts for about one-third of epilepsy patients worldwide. Peimine, a main active component of Fritillaria, has been reported to show anti-inflammatory effects. However, its potential therapeutic role in DRE is not yet fully understood. In this work, a DRE rat model was established by injecting 1 μg kainic acid (KA), followed by a 250 mg/kg administration of valproic acid (VPA) from day 4-31. Rats were treated with different doses of peimine (2.5 mg/kg, 5 mg/kg and 10 mg/kg) daily from day 32-62. In vitro, BV-2 microglia were exposed to different doses of peimine (7.5 μg/ml, 15 μg/ml, and 30 μg/ml) in presence of LPS. The aim of this study was to investigate the potential therapeutic effects of peimine on DRE. The results showed that peimine efficiently suppressed the KA-induced epileptic behaviors of rats in a dose-dependent manner, as recorded by electroencephalography. Furthermore, peimine ameliorated hippocampal neuron injury in DRE rats, and promoted an M1-to-M2 microglial phenotype shift in a dose-dependent manner. Mechanistically, peimine inhibited the TLR4/NF-κB/HIF-1α signaling pathway both in vivo and in vitro. Additionally, peimine suppressed the apoptosis of primary neurons induced by LPS-treated microglia. In conclusion, peimine augments the microglial polarization towards an M2 phenotype by inhibiting the TLR4/NF-κB/HIF-1α signaling pathway, thereby attenuating DRE.

Age-Dependent Phenomena of 6-Hz Corneal Kindling Model in Mice

Although numerous studies have acknowledged disparities in epilepsy-related disease processes between young and aged animals, little is known about how epilepsy changes from young adulthood to middle age. This study investigates the impact of aging on 6-Hz corneal kindling in young-adult mice and middle-aged mice. We found that the kindling acquisition of the 6-Hz corneal kindling model was delayed in middle-aged mice when compared to young-adult mice. While the seizure stage and incidence of generalized seizures (GS) were similar between the two age groups, the duration of GS in the kindled middle-aged mice was shorter than that in the kindled young-adult mice. Besides, all kindled mice, regardless of age, were resistant to phenytoin sodium (PHT), valproate sodium (VPA), and lamotrigine (LGT), whereas middle-aged mice exhibited higher levetiracetam (LEV) resistance compared to young-adult mice. Both age groups of kindled mice displayed hyperactivity and impaired memory, which are common behavioral characteristics associated with epilepsy. Furthermore, middle-aged mice displayed more pronounced astrogliosis in the hippocampus. Additionally, the expression of Brain-Derived Neurotrophic Factor (BDNF) was lower in middle-aged mice than in young-adult mice prior to kindling. These data demonstrate that both the acquisition and expression of 6-Hz corneal kindling are attenuated in middle-aged mice, while hippocampal astrogliosis and pharmacological resistance are more pronounced in this age group. These results underscore the importance of considering age-related factors when utilizing the 6-Hz corneal kindling model in mice of varying age groups.

Consensus Guideline on the Management of Epilepsy in Egypt: A National Delphi Consensus Study

OBJECTIVE

In epilepsy, early diagnosis, accurate determination of epilepsy type, proper selection of antiseizure medication, and monitoring are all essential. However, despite recent therapeutic advances and conceptual reconsiderations in the classification and management of epilepsy, serious gaps are still encountered in day-to-day practice in Egypt as well as several other resource-limited countries. Premature mortality, poor quality of life, socio-economic burden, cognitive problems, poor treatment outcomes, and comorbidities are major challenges that require urgent actions to be implemented at all levels. In recognition of this, a group of Egyptian epilepsy experts met through a series of consecutive meetings to specify the main concepts concerning the diagnosis and management of epilepsy, with the ultimate goal of establishing a nationwide Egyptian consensus.

METHODS

The consensus was developed through a modified Delphi methodology. A thorough review of the most recent relevant literature and international guidelines was performed to evaluate their applicability to the Egyptian situation. Afterward, several remote and live rounds were scheduled to reach a final agreement for all listed statements.

RESULTS

Of 278 statements reviewed in the first round, 256 achieved ≥80% agreement. Live discussion and refinement of the 22 statements that did not reach consensus during the first round took place, followed by final live voting then consensus was achieved for all remaining statements.

SIGNIFICANCE

With the implementation of these unified recommendations, we believe this will bring about substantial improvements in both the quality of care and treatment outcomes for persons with epilepsy in Egypt.

PLAIN LANGUAGE SUMMARY

This work represents the efforts of a group of medical experts to reach an agreement on the best medical practice related to people with epilepsy based on previously published recommendations while taking into consideration applicable options in resource-limited countries. The publication of this document is expected to minimize many malpractice issues and pave the way for better healthcare services on both individual and governmental levels.

Light-Driven Sodium Pump as a Potential Tool for the Control of Seizures in Epilepsy

The marine flavobacterium Krokinobactereikastus light-driven sodium pump (KR2) generates an outward sodium ion current under 530 nm light stimulation, representing a promising optogenetic tool for seizure control. However, the specifics of KR2 application to suppress epileptic activity have not yet been addressed. In the present study, we investigated the possibility of KR2 photostimulation to suppress epileptiform activity in mouse brain slices using the 4-aminopyrindine (4-AP) model. We injected the adeno-associated viral vector (AAV-PHP.eB-hSyn-KR2-YFP) containing the KR2 sodium pump gene enhanced with appropriate trafficking tags. KR2 expression was observed in the lateral entorhinal cortex and CA1 hippocampus. Using whole-cell patch clamp in mouse brain slices, we show that KR2, when stimulated with LED light, induces a substantial hyperpolarization of entorhinal neurons. However, continuous photostimulation of KR2 does not interrupt ictal discharges in mouse entorhinal cortex slices induced by a solution containing 4-AP. KR2-induced hyperpolarization strongly activates neuronal HCN channels. Consequently, turning off photostimulation resulted in HCN channel-mediated rebound depolarization accompanied by a transient increase in spontaneous network activity. Using low-frequency pulsed photostimulation, we induced the generation of short HCN channel-mediated discharges that occurred in response to the light stimulus being turned off; these discharges reliably interrupt ictal activity. Thus, low-frequency pulsed photostimulation of KR2 can be considered as a potential tool for controlling epileptic seizures.

Voxeloc: A time-saving graphical user interface for localizing and visualizing stereo-EEG electrodes

BACKGROUND

Thanks to its unrivalled spatial and temporal resolutions and signal-to-noise ratio, intracranial EEG (iEEG) is becoming a valuable tool in neuroscience research. To attribute functional properties to cortical tissue, it is paramount to be able to determine precisely the localization of each electrode with respect to a patient's brain anatomy. Several software packages or pipelines offer the possibility to localize manually or semi-automatically iEEG electrodes. However, their reliability and ease of use may leave to be desired.

NEW METHOD

Voxeloc (voxel electrode locator) is a Matlab-based graphical user interface to localize and visualize stereo-EEG electrodes. Voxeloc adopts a semi-automated approach to determine the coordinates of each electrode contact, the user only needing to indicate the deep-most contact of each electrode shaft and another point more proximally.

RESULTS

With a deliberately streamlined functionality and intuitive graphical user interface, the main advantages of Voxeloc are ease of use and inter-user reliability. Additionally, oblique slices along the shaft of each electrode can be generated to facilitate the precise localization of each contact. Voxeloc is open-source software and is compatible with the open iEEG-BIDS (Brain Imaging Data Structure) format.

COMPARISON WITH EXISTING METHODS

Localizing full patients' iEEG implants was faster using Voxeloc than two comparable software packages, and the inter-user agreement was better.

CONCLUSIONS

Voxeloc offers an easy-to-use and reliable tool to localize and visualize stereo-EEG electrodes. This will contribute to democratizing neuroscience research using iEEG.

A review of cell-type specific circuit mechanisms underlying epilepsy

Epilepsy is a prevalent neurological disorder, yet its underlying mechanisms remain incompletely understood. Accumulated studies have indicated that epilepsy is characterized by abnormal neural circuits. Understanding the circuit mechanisms is crucial for comprehending the pathogenesis of epilepsy. With advances in tracing and modulating tools for neural circuits, some epileptic circuits have been uncovered. This comprehensive review focuses on the circuit mechanisms underlying epilepsy in various neuronal subtypes, elucidating their distinct roles. Epileptic seizures are primarily characterized by the hyperactivity of glutamatergic neurons and inhibition of GABAergic neurons. However, specific activated GABAergic neurons and suppressed glutamatergic neurons exacerbate epilepsy through preferentially regulating the activity of GABAergic neurons within epileptic circuits. Distinct subtypes of GABAergic neurons contribute differently to epileptic activities, potentially due to their diverse connection patterns. Moreover, identical GABAergic neurons may assume distinct roles in different stages of epilepsy. Both GABAergic neurons and glutamatergic neurons with long-range projecting fibers innervate multiple nuclei; nevertheless, not all of these circuits contribute to epileptic activities. Epileptic circuits originating from the same nuclei may display diverse contributions to epileptic activities, and certain glutamatergic circuits from the same nuclei may even exert opposing effects on epilepsy. Neuromodulatory neurons, including cholinergic, serotonergic, dopaminergic, and noradrenergic neurons, are also implicated in epilepsy, although the underlying circuit mechanisms remain poorly understood. These studies suggest that epileptic nuclei establish intricate connections through cell-type-specific circuits and play pivotal roles in epilepsy. However, there are still limitations in knowledge and methods, and further understanding of epileptic circuits is crucial, particularly in the context of refractory epilepsy.

Antiseizure medication adherence and epilepsy surgery attitude in people with epilepsy in Morocco: A cross-sectional study

We determine the proportion of non-Antiseizure Medication Adherence (non-AMA) and refusal attitude towards Epilepsy Surgery (ES) and their associated factors in Moroccan People With Epilepsy (PWE). A cross-sectional study was conducted (December 2021-December 2022) among adult Moroccan PWE. PWE were interviewed for their reactions to AMA and the ES attitude. Their medical files were processed to complete their sociodemographic and clinical data. Data were analyzed by the Statistical Package for Social Sciences (SPSS) software 21.0. A Chi-square test was performed to compare variables and multivariate logistic regression was used to highlight associations. Statistical tests were considered significant at a p-value ≤ 0.05 for a Confidence Interval (CI) of 95 %. The median age of our sample (n = 294) was 38 years (IQR: 25.00-55.00). Non-AMA was noted in 24.5 % with indifference as the main reason (55.6 %). ES refusal was found in 33.3 %, attributed mostly to apprehension (61.2 %). In the multivariate analysis, male sex (aOR = 1.94; 95 %CI: 1.03-3.64) and the existence of a family history of epilepsy (aOR = 1.96; 95 %CI: 1.02-3.75) were the factors associated with the non-AMA, whereas the use of allopathic treatments (aOR = 2.32; 95 %CI: 1.20-4.51), exclusively focal or generalized (not combined) seizures (aOR = 2.66; 95 %CI: 1.36-5.21) and the combination of a generic with the originator ASM (aOR = 2.64; 95 %CI: 1.12-6.18) were the predictive factors with the ES refusal attitude. The proportions found of non-AMA and ES refusal were relatively low compared to other studies, which may indicate the effort that medical staff have devoted recently to raising awareness of the importance of PWE's therapeutic involvement.

In-depth Mechanism, Challenges, and Opportunities of Delivering Therapeutics in Brain Using Intranasal Route

Central nervous system-related disorders have become a continuing threat to human life and the current statistic indicates an increasing trend of such disorders worldwide. The primary therapeutic challenge, despite the availability of therapies for these disorders, is to sustain the drug's effective concentration in the brain while limiting its accumulation in non-targeted areas. This is attributed to the presence of the blood-brain barrier and first-pass metabolism which limits the transportation of drugs to the brain irrespective of popular and conventional routes of drug administration. Therefore, there is a demand to practice alternative routes for predictable drug delivery using advanced drug delivery carriers to overcome the said obstacles. Recent research attracted attention to intranasal-to-brain drug delivery for promising targeting therapeutics in the brain. This review emphasizes the mechanisms to deliver therapeutics via different pathways for nose-to-brain drug delivery with recent advancements in delivery and formulation aspects. Concurrently, for the benefit of future studies, the difficulties in administering medications by intranasal pathway have also been highlighted.

Virus-Induced Epilepsy vs. Epilepsy Patients Acquiring Viral Infection: Unravelling the Complex Relationship for Precision Treatment

The intricate relationship between viruses and epilepsy involves a bidirectional interaction. Certain viruses can induce epilepsy by infecting the brain, leading to inflammation, damage, or abnormal electrical activity. Conversely, epilepsy patients may be more susceptible to viral infections due to factors, such as compromised immune systems, anticonvulsant drugs, or surgical interventions. Neuroinflammation, a common factor in both scenarios, exhibits onset, duration, intensity, and consequence variations. It can modulate epileptogenesis, increase seizure susceptibility, and impact anticonvulsant drug pharmacokinetics, immune system function, and brain physiology. Viral infections significantly impact the clinical management of epilepsy patients, necessitating a multidisciplinary approach encompassing diagnosis, prevention, and treatment of both conditions. We delved into the dual dynamics of viruses inducing epilepsy and epilepsy patients acquiring viruses, examining the unique features of each case. For virus-induced epilepsy, we specify virus types, elucidate mechanisms of epilepsy induction, emphasize neuroinflammation's impact, and analyze its effects on anticonvulsant drug pharmacokinetics. Conversely, in epilepsy patients acquiring viruses, we detail the acquired virus, its interaction with existing epilepsy, neuroinflammation effects, and changes in anticonvulsant drug pharmacokinetics. Understanding this interplay advances precision therapies for epilepsy during viral infections, providing mechanistic insights, identifying biomarkers and therapeutic targets, and supporting optimized dosing regimens. However, further studies are crucial to validate tools, discover new biomarkers and therapeutic targets, and evaluate targeted therapy safety and efficacy in diverse epilepsy and viral infection scenarios.

Predictors of therapeutic response following thalamic neuromodulation for drug-resistant pediatric epilepsy: A systematic review and individual patient data meta-analysis

We sought to perform a systematic review and individual participant data meta-analysis to identify predictors of treatment response following thalamic neuromodulation in pediatric patients with medically refractory epilepsy. Electronic databases (MEDLINE, Ovid, Embase, and Cochrane) were searched, with no language or data restriction, to identify studies reporting seizure outcomes in pediatric populations following deep brain stimulation (DBS) or responsive neurostimulation (RNS) implantation in thalamic nuclei. Studies featuring individual participant data of patients with primary or secondary generalized drug-resistant epilepsy were included. Response to therapy was defined as >50% reduction in seizure frequency from baseline. Of 417 citations, 21 articles reporting on 88 participants were eligible. Mean age at implantation was 13.07 ± 3.49 years. Fifty (57%) patients underwent DBS, and 38 (43%) RNS. Sixty (68%) patients were implanted in centromedian nucleus and 23 (26%) in anterior thalamic nucleus, and five (6%) had both targets implanted. Seventy-four (84%) patients were implanted bilaterally. The median time to last follow-up was 12 months (interquartile range = 6.75-26.25). Sixty-nine percent of patients achieved response to treatment. Age, target, modality, and laterality had no significant association with response in univariate logistic regression. Until thalamic neuromodulation gains widespread approval for use in pediatric patients, data on efficacy will continue to be limited to small retrospective cohorts and case series. The inherent bias of these studies can be overcome by using individual participant data. Thalamic neuromodulation appears to be a safe and effective treatment for epilepsy. Larger, prolonged prospective, multicenter studies are warranted to further evaluate the efficacy of DBS over RNS in this patient population where resection for curative intent is not a safe option.

ATF5-regulated Mitochondrial Unfolded Protein Response Attenuates Neuronal Damage in Epileptic Rat by Reducing Endoplasmic Reticulum Stress Through Mitochondrial ROS

Endoplasmic reticulum (ER) dysfunction caused by excessive ER stress is a crucial mechanism underlying seizures-induced neuronal injury. Studies have shown that mitochondrial reactive oxygen species (ROS) are closely related to ER stress, and our previous study showed that activating transcription factor 5 (ATF5)-regulated mitochondrial unfolded protein response (mtUPR) modulated mitochondrial ROS generation in a hippocampal neuronal culture model of seizures. However, the effects of ATF5-regulated mtUPR on ER stress and the underlying mechanisms remain uncertain in epilepsy. In this study, ATF5 upregulation by lentivirus infection attenuated seizures-induced neuronal damage and apoptosis in a rat model of pilocarpine-induced epilepsy, whereas ATF5 downregulation by lentivirus infection had the opposite effects. ATF5 upregulation potentiated mtUPR by increasing the expression of mitochondrial chaperone heat shock protein 60 (HSP60) and caseinolytic protease proteolytic subunit (ClpP) and reducing mitochondrial ROS generation in pilocarpine-induced seizures in rats. Additionally, upregulation of ATF5 reduced the expression of glucose-regulated protein 78 (GRP78), protein kinase RNA-like endoplasmic reticulum kinase (PERK), activating transcription factor 4 (ATF4), and C/EBP homologous protein (CHOP), suggesting suppression of ER stress; Moreover, ATF5 upregulation attenuated apoptosis-related proteins such as B-cell lymphoma-2 (BCL2) downregulation, BCL2-associated X (BAX) and cleaved-caspase-3 upregulation. However, ATF5 downregulation exerted the opposite effects. Furthermore, pretreatment with the mitochondria-targeted antioxidant mito-TEMPO attenuated the harmful effects of ATF5 downregulation on ER stress and neuronal apoptosis by reducing mitochondrial ROS generation. Overall, our study suggested that ATF5-regulated mtUPR exerted neuroprotective effects against pilocarpine-induced seizures in rats and the underlying mechanisms might involve mitochondrial ROS-mediated ER stress.

Nanotechnology-based Nose-to-brain Delivery in Epilepsy: A NovelApproach to Diagnosis and Treatment

Epilepsy is a serious neurological disease, and scientists have a significant challenge in developing a noninvasive treatment for the treatment of epilepsy. The goal is to provide novel ideas for improving existing and future anti-epileptic medications. The injection of nano treatment via the nose to the brain is being considered as a possible seizure control method. Various nasal medicine nanoformulations have the potential to cure epilepsy. Investigations with a variety of nose-to-brain dosing methods for epilepsy treatment have yielded promising results. After examining global literature on nanotechnology and studies, the authors propose nasal administration with nanoformulations as a means to successfully treat epilepsy. The goal of this review is to look at the innovative application of nanomedicine for epilepsy treatment via nose-to-brain transfer, with a focus on the use of nanoparticles for load medicines. When nanotechnology is combined with the nose to brain approach, treatment efficacy can be improved through site specific delivery. Furthermore, this technique of administration decreases adverse effects and patient noncompliance encountered with more traditional procedures.

The role of molecular chaperones in the mechanisms of epileptogenesis

Epilepsy is a group of neurological diseases which requires significant economic costs for the treatment and care of patients. The central point of epileptogenesis stems from the failure of synaptic signal transmission mechanisms, leading to excessive synchronous excitation of neurons and characteristic epileptic electroencephalogram activity, in typical cases being manifested as seizures and loss of consciousness. The causes of epilepsy are extremely diverse, which is one of the reasons for the complexity of selecting a treatment regimen for each individual case and the high frequency of pharmacoresistant cases. Therefore, the search for new drugs and methods of epilepsy treatment requires an advanced study of the molecular mechanisms of epileptogenesis. In this regard, the investigation of molecular chaperones as potential mediators of epileptogenesis seems promising because the chaperones are involved in the processing and regulation of the activity of many key proteins directly responsible for the generation of abnormal neuronal excitation in epilepsy. In this review, we try to systematize current data on the role of molecular chaperones in epileptogenesis and discuss the prospects for the use of chemical modulators of various chaperone groups' activity as promising antiepileptic drugs.

CircRNA SRRM4 affects glucose metabolism by regulating PKM alternative splicing via SRSF3 deubiquitination in epilepsy

OBJECTIVES

Several reports suggest that epigenetic therapy may be a potential method for treating epilepsy, and circular RNAs (circRNAs) play important roles in mediating the epigenetic mechanisms associated with epilepsy; however, currently there are no effective treatment methods to prevent the progression of epileptogenesis. The circRNA serine/arginine repetitive matrix 4 (circSRRM4) was found to exert regulatory effects in temporal lobe epilepsy (TLE); however, the mechanisms involved are still unknown.

MATERIALS AND METHODS

To elucidate the molecular mechanism of circSRRM4, we investigated human epileptic brain tissue, epileptic rats, neuron and astrocyte cell lines using RT-qPCR, western blot, fluorescence in situ hybridisation, immunofluorescence staining, Nissl stain, micro-PET-CT, RNA-pulldown, liquid chromatography-mass spectrometry, and RBP immunoprecipitation techniques. Furthermore, we evaluated the pyruvate kinase M1/2 (PKM) expression patterns in the human and rat models of TLE.

RESULTS

We detected the increased circSRRM4 expression in the hypometabolic lesions of patients with TLE and discovered that circSrrm4 has specific spatiotemporal characteristics in rats with kainic acid-induced epilepsy. The decreased PKM1 expression and increased PKM2 expression were similar to the Warburg effect in tumours. Notably, circSrrm4 silencing reduced the incidence and frequency of epilepsy, improved local hypometabolism, and prevented neuronal loss and astrocyte activation.

CONCLUSION

PKM2 promotes lactic acid production in the astrocytes by inducing glycolysis, thereby contributing to the energy source for epileptic seizures. Notably, circSRRM4 combines with and inhibits serine and arginine rich splicing factor 3 (SRSF3) from joining the ubiquitin-proteasome pathway, improving the SRSF3-regulated alternative splicing of PKM, and consequently stimulating glycolysis in cells.

Innovative treatments for epilepsy: Venom peptides, cannabinoids, and neurostimulation

Antiepileptic drugs have been successfully treating epilepsy and providing individuals sustained seizure freedom. However, about 30% of the patients with epilepsy present drug resistance, which means they are not responsive to the pharmacological treatment. Considering this, it becomes extremely relevant to pursue alternative therapeutic approaches, in order to provide appropriate treatment for those patients and also improve their quality of life. In the light of that, this review aims to discuss some innovative options for the treatment of epilepsy, which are currently under investigation, addressing strategies that go from therapeutic compounds to clinical procedures. For instance, peptides derived from animal venoms, such as wasps, spiders, and scorpions, demonstrate to be promising antiepileptic molecules, acting on a variety of targets. Other options are cannabinoids and compounds that modulate the endocannabinoid system, since it is now known that this network is involved in the pathophysiology of epilepsy. Furthermore, neurostimulation is another strategy, being an alternative clinical procedure for drug-resistant patients who are not eligible for palliative surgeries.

Dysfunction of ABC Transporters at the Surface of BBB: Potential Implications in Intractable Epilepsy and Applications of Nanotechnology Enabled Drug Delivery

Epilepsy is a chronic neurological disorder affecting 70 million people globally. One of the fascinating attributes of brain microvasculature is the (BBB), which controls a chain of distinct features that securely regulate the molecules, ions, and cells movement between the blood and the parenchyma. The barrier's integrity is of paramount importance and essential for maintaining brain homeostasis, as it offers both physical and chemical barriers to counter pathogens and xenobiotics. Dysfunction of various transporters in the (BBB), mainly ATP binding cassette (ABC), is considered to play a vital role in hampering the availability of antiepileptic drugs into the brain. ABC (ATP-binding cassette) transporters constitute a most diverse protein superfamily, which plays an essential part in various biological processes, including cell homeostasis, cell signaling, uptake of nutrients, and drug metabolism. Moreover, it plays a crucial role in neuroprotection by out-flowing various internal and external toxic substances from the interior of a cell, thus decreasing their buildup inside the cell. In humans, forty-eight ABC transporters have been acknowledged and categorized into subfamilies A to G based on their phylogenetic analysis. ABC subfamilies B, C, and G, impart a vital role at the BBB in guarding the brain against the entrance of various xenobiotic and their buildup. The illnesses of the central nervous system have received a lot of attention lately Owing to the existence of the BBB, the penetration effectiveness of most CNS medicines into the brain parenchyma is very limited (BBB). In the development of neurological therapies, BBB crossing for medication delivery to the CNS continues to be a major barrier. Nanomaterials with BBB cross ability have indeed been extensively developed for the treatment of CNS diseases due to their advantageous properties. This review will focus on multiple possible factors like inflammation, oxidative stress, uncontrolled recurrent seizures, and genetic polymorphisms that result in the deregulation of ABC transporters in epilepsy and nanotechnology-enabled delivery across BBB in epilepsy.

The Efficacy and Safety of Ketogenic Diets in Drug-Resistant Epilepsy in Children and Adolescents: a Systematic Review of Randomized Controlled Trials

PURPOSE OF REVIEW

Drug-resistant epilepsy represents around one-quarter of epilepsies worldwide. Although ketogenic diets (KD) have been used for refractory epilepsy since 1921, the past 15 years have witnessed an explosion of KD use in the management of epilepsy. We aimed to review evidence from randomized controlled trials (RCTs) regarding the efficacy and safety of KD in drug-resistant epilepsy in children and adolescents.

RECENT FINDINGS

A literature search was performed in the Pubmed, Cohrane, Scopus, ClinicalTrials.gov, and Google Scholar databases. Predefined criteria were implemented regarding data extraction and study quality. Data were extracted from 14 RCTs in 1114 children and adolescents aged from 6 months to 18 years. Primary outcome was seizure reduction after the intervention. In 6 out of the 14 studies, there was a statistical significant seizure reduction by > 50% in the KD-treated group compared with the control group over a follow-up of 3-4 months. Secondary outcomes were adverse events, seizure severity, quality of life, and behavior. Gastrointestinal symptoms were the most frequent adverse events. Serious adverse events were rare. We conclude that the KD is an effective treatment for drug-resistant epilepsy in children and adolescents. Accordingly, RCTs investigating long-term impact, cognitive and behavioral effects, and cost-effectiveness are much anticipated.

Gene and Cell Therapy for Epilepsy: A Mini Review

Epilepsy is a chronic non-infectious disease of the brain, characterized primarily by recurrent unprovoked seizures, defined as an episode of disturbance of motor, sensory, autonomic, or mental functions resulting from excessive neuronal discharge. Despite the advances in the treatment achieved with the use of antiepileptic drugs and other non-pharmacological therapies, about 30% of patients suffer from uncontrolled seizures. This review summarizes the currently available methods of gene and cell therapy for epilepsy and discusses the development of these approaches. Currently, gene therapy for epilepsy is predominantly adeno-associated virus (AAV)-mediated delivery of genes encoding neuro-modulatory peptides, neurotrophic factors, enzymes, and potassium channels. Cell therapy for epilepsy is represented by the transplantation of several types of cells such as mesenchymal stem cells (MSCs), bone marrow mononuclear cells, neural stem cells, and MSC-derived exosomes. Another approach is encapsulated cell biodelivery, which is the transplantation of genetically modified cells placed in capsules and secreting various therapeutic agents. The use of gene and cell therapy approaches can significantly improve the condition of patient with epilepsy. Therefore, preclinical, and clinical studies have been actively conducted in recent years to prove the benefits and safety of these strategies.

Reorganization of Parvalbumin Immunopositive Perisomatic Innervation of Principal Cells in Focal Cortical Dysplasia Type IIB in Human Epileptic Patients

Focal cortical dysplasia (FCD) is one of the most common causes of drug-resistant epilepsy. As several studies have revealed, the abnormal functioning of the perisomatic inhibitory system may play a role in the onset of seizures. Therefore, we wanted to investigate whether changes of perisomatic inhibitory inputs are present in FCD. Thus, the input properties of abnormal giant- and control-like principal cells were examined in FCD type IIB patients. Surgical samples were compared to controls from the same cortical regions with short postmortem intervals. For the study, six subjects were selected/each group. The perisomatic inhibitory terminals were quantified in parvalbumin and neuronal nuclei double immunostained sections using a confocal fluorescent microscope. The perisomatic input of giant neurons was extremely abundant, whereas control-like cells of the same samples had sparse inputs. A comparison of pooled data shows that the number of parvalbumin-immunopositive perisomatic terminals contacting principal cells was significantly larger in epileptic cases. The analysis showed some heterogeneity among epileptic samples. However, five out of six cases had significantly increased perisomatic input. Parameters of the control cells were homogenous. The reorganization of the perisomatic inhibitory system may increase the probability of seizure activity and might be a general mechanism of abnormal network activity.

DREADDs in Epilepsy Research: Network-Based Review

Epilepsy can be interpreted as altered brain rhythms from overexcitation or insufficient inhibition. Chemogenetic tools have revolutionized neuroscience research because they allow "on demand" excitation or inhibition of neurons with high cellular specificity. Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) are the most frequently used chemogenetic techniques in epilepsy research. These engineered muscarinic receptors allow researchers to excite or inhibit targeted neurons with exogenous ligands. As a result, DREADDs have been applied to investigate the underlying cellular and network mechanisms of epilepsy. Here, we review the existing literature that has applied DREADDs to understand the pathophysiology of epilepsy. The aim of this review is to provide a general introduction to DREADDs with a focus on summarizing the current main findings in experimental epilepsy research using these techniques. Furthermore, we explore how DREADDs may be applied therapeutically as highly innovative treatments for epilepsy.

Efficacy and safety of VNS therapy or continued medication management for treatment of adults with drug-resistant epilepsy: systematic review and meta-analysis

Vagus nerve stimulation (VNS) Therapy® is an adjunctive neurostimulation treatment for people with drug-resistant epilepsy (DRE) who are unwilling to undergo resective surgery, have had unsuccessful surgery or are unsuitable for surgery. A systematic review and meta-analysis were conducted to determine the treatment effects of VNS Therapy as an adjunct to anti-seizure medications (ASMs) for the management of adults with DRE. A literature search was performed in August 2020 of the Medline®, Medline® Epub Ahead of Print, Embase, and the Cochrane library databases. Outcomes examined included reduction in seizure frequency, seizure freedom, ASM load, discontinuations, and serious adverse events (SAEs). Comparators included best medical practice, ASMs, low-stimulation or sham VNS Therapy. Four RCTs and six comparative observational studies were identified for inclusion. Against comparators, individuals treated with VNS had a significantly better odds of experiencing a ≥ 50% reduction in seizure frequency (OR: 2.27 [95% CI 1.47, 3.51]; p = 0.0002), a ≥ 75% reduction in seizure frequency (OR: 3.56 [95% CI 1.59, 7.98]; p = 0.002) and a reduced risk for increased ASM load (risk ratio: 0.36 [95% CI 0.21, 0.62]; p = 0.0002). There was no difference in the odds of discontinuation or the rate of SAEs between VNS versus comparators. This meta-analysis demonstrated the benefits of VNS Therapy in people with DRE, which included improvement in seizure frequency without an increase in the rate of SAEs or discontinuations, thereby supporting the consideration of VNS Therapy for people who are not responding to ASMs and those unsuitable or unwilling to undergo surgery.

The Occurrence of Seizure Clusters in Patients With Epilepsy Is Partly Determined by Epilepsy Severity: A Single-Center Retrospective Observational Study

Purpose: This retrospective observational study aimed to investigate the self-reported prevalence of seizure clusters (SCs) in patients with epilepsy (PWE) and its relationship with clinical characteristics.

Methods: We retrospectively analyzed data from consecutive PWE from our hospital in northeastern China. Data were collected from the databank of a tertiary epilepsy center. Logistic regression models were employed to investigate the relationships between the individual patient demographic/clinical variables and the occurrence of SC.

Results: In total, 606 consecutive PWE were included in the final analysis, and 268 (44.2%) patients experienced at least one seizure cluster. In multivariate logistic regression models, age (OR: 1.014; 95% CI: 1.002–1.027; p = 0.02), seizure frequency (OR: 2.08; 95% CI: 1.555–2.783; p < 0.001), multiple seizure types (OR: 5.111; 95% CI: 1.737–15.043; p = 0.003), number of current anti-seizure medications (ASM) (OR: 1.533; 95% CI: 1.15–2.042; p = 0.004), drug-resistant epilepsy (OR: 1.987; 95% CI: 1.159–3.407; p = 0.013), and a history of status epilepticus (OR: 1.903; 95% CI: 1.24–2.922; p = 0.003) were independent variables associated with a history of SC in PWE.

Conclusion: Seizure clusters (SCs) are common occurrences at our study center. The occurrence of SC in individuals with epilepsy, to some extent, is determined by the epilepsy severity.

Prophylactic Activation of Shh Signaling Attenuates TBI-Induced Seizures in Zebrafish by Modulating Glutamate Excitotoxicity through Eaat2a

Approximately 2 million individuals experience a traumatic brain injury (TBI) every year in the United States. Secondary injury begins within minutes after TBI, with alterations in cellular function and chemical signaling that contribute to excitotoxicity. Post-traumatic seizures (PTS) are experienced in an increasing number of TBI individuals that also display resistance to traditional anti-seizure medications (ASMs). Sonic hedgehog (Shh) is a signaling pathway that is upregulated following central nervous system damage in zebrafish and aids injury-induced regeneration. Using a modified Marmarou weight drop on adult zebrafish, we examined PTS following TBI and Shh modulation. We found that inhibiting Shh signaling by cyclopamine significantly increased PTS in TBI fish, prolonged the timeframe PTS was observed, and decreased survival across all TBI severities. Shh-inhibited TBI fish failed to respond to traditional ASMs, but were attenuated when treated with CNQX, which blocks ionotropic glutamate receptors. We found that the Smoothened agonist, purmorphamine, increased Eaat2a expression in undamaged brains compared to untreated controls, and purmorphamine treatment reduced glutamate excitotoxicity following TBI. Similarly, purmorphamine reduced PTS, edema, and cognitive deficits in TBI fish, while these pathologies were increased and/or prolonged in cyclopamine-treated TBI fish. However, the increased severity of TBI phenotypes with cyclopamine was reduced by cotreating fish with ceftriaxone, which induces Eaat2a expression. Collectively, these data suggest that Shh signaling induces Eaat2a expression and plays a role in regulating TBI-induced glutamate excitotoxicity and TBI sequelae.

Dendritic and Spine Loss in Epilepsy: What Seizures Got to Do With It?

[Box: see text]

MEG Node Degree Differences in Patients with Focal Epilepsy vs. Controls-Influence of Experimental Conditions

Drug-resistant epilepsy can be most limiting for patients, and surgery represents a viable therapy option. With the growing research on the human connectome and the evidence of epilepsy being a network disorder, connectivity analysis may be able to contribute to our understanding of epilepsy and may be potentially developed into clinical applications. In this magnetoencephalographic study, we determined the whole-brain node degree of connectivity levels in patients and controls. Resting-state activity was measured at five frequency bands in 15 healthy controls and 15 patients with focal epilepsy of different etiologies. The whole-brain all-to-all imaginary part of coherence in source space was then calculated. Node degree was determined and parcellated and was used for further statistical evaluation. In comparison to controls, we found a significantly higher overall node degree in patients with lesional and non-lesional epilepsy. Furthermore, we examined the conditions of high/reduced vigilance and open/closed eyes in controls, to analyze whether patient node degree levels can be achieved. We evaluated intraclass-correlation statistics (ICC) to evaluate the reproducibility. Connectivity and specifically node degree analysis could present new tools for one of the most common neurological diseases, with potential applications in epilepsy diagnostics.

Treatment Outcome and Risk Factors of Adult Newly Diagnosed Epilepsy: A Prospective Hospital-Based Study in Northeast China

Objective: The study was conducted to summarize the treatment outcomes of newly diagnosed epilepsy (NDE) and analyse the risk factors for refractory epilepsy (RE) in Northeast China.

Methods: A total of 466 adult patients with NDE were consecutively enrolled in this programme. Clinical data were collected at baseline and each follow-up. Several scales concerning recognition and mood were also completed at the first visit.

Results: Seizure-free status was achieved by 52% (n = 244) of the patients; however, 15% (n = 68) manifested RE. A total of 286 (61%) patients continued with the first ASM as monotherapy, among which 186 (40%) patients became seizure-free. Fifteen (22%) patients with RE became seizure-free following ASM adjustment and 34 patients (14%) had breakthrough seizures after being classified as seizure-free. One patient developed RE after attaining seizure-free status. Breakthrough seizures during the first expected interictal interval [Odds ratio (OR) = 5.81, 95% CI: 2.70–12.50], high seizure frequency at baseline (OR = 1.24, 95% CI: 1.04–1.49), younger age of onset (OR = 1.42, 95% CI: 1.12–1.79), and male sex (OR = 2.64, 95% CI: 1.26–5.53) were risk factors for RE.

Significance: Treatment outcomes of the majority of NDE cases are good. New risk factors could help physicians more promptly and accurately identify patients who are likely to develop RE. Seizure-free state is not long enough to commence the withdrawal of ASMs. RE is not permanent and seizure-free may be achieved subsequently by appropriate drug adjustment.

Melatonin Pretreatment Protects Against Status epilepticus, Glutamate Transport, and Oxidative Stress Induced by Kainic Acid in Zebrafish

Status epilepticus (SE) develops from abnormal electrical discharges, resulting in neuronal damage. Current treatments include antiepileptic drugs. However, the most common drugs used to treat seizures may sometimes be ineffective and have many side effects. Melatonin is an endogenous physiological hormone that is considered an alternative treatment for neurological disorders because of its free radical scavenging property. Thus, this study aimed to determine the effects of melatonin pretreatment on SE by inducing glutamatergic hyperstimulation in zebrafish. Seizures were induced in zebrafish using kainic acid (KA), a glutamate analog, and the seizure intensity was recorded for 60 min. Melatonin treatment for 7 days showed a decrease in seizure intensity (28%), latency to reach score 5 (14 min), and duration of SE (29%). In addition, melatonin treatment attenuated glutamate transporter levels, which significantly decreased in the zebrafish brain after 12 h of KA-induced seizures. Melatonin treatment reduced the increase in oxidative stress by reactive oxygen species formation through thiobarbituric acid reactive substances and 2',7'-dichiorofluorescin, induced by KA-seizure. An imbalance of antioxidant enzyme activities such as superoxide dismutase and catalase was influenced by melatonin and KA-induced seizures. Our study indicates that melatonin promotes a neuroprotective response against the epileptic profile in zebrafish. These effects could be related to the modulation of glutamatergic neurotransmission, recovery of glutamate uptake, and oxidative stress parameters in the zebrafish brain.

Suppressive Effects of Transient Receptor Potential Melastatin 8 Agonist on Epileptiform Discharges and Epileptic Seizures

Epilepsy is a relatively common condition, but more than 30% of patients have refractory epilepsy that is inadequately controlled by or is resistant to multiple drug treatments. Thus, new antiepileptic drugs based on newly identified mechanisms are required. A previous report revealed the suppressive effects of transient receptor potential melastatin 8 (TRPM8) activation on penicillin G-induced epileptiform discharges (EDs). However, it is unclear whether TRPM8 agonists suppress epileptic seizures or affect EDs or epileptic seizures in TRPM8 knockout (TRPM8KO) mice. We investigated the effects of TRPM8 agonist and lack of TRPM8 channels on EDs and epileptic seizures. Mice were injected with TRPM8 agonist 90 min after or 30 min before epilepsy-inducer injection, and electrocorticograms (ECoGs) were recorded under anesthesia, while behavior was monitored when awake. TRPM8 agonist suppressed EDs and epileptic seizures in wildtype (WT) mice, but not in TRPM8KO mice. In addition, TRPM8KO mice had a shorter firing latency of EDs, and EDs and epileptic seizures were deteriorated by the epilepsy inducer compared with those in WT mice, with the EDs being more easily propagated to the contralateral side. These findings suggest that TRPM8 activation in epileptic regions has anti-epileptic effects.

Microbiota-Gut-Brain Axis and Epilepsy: A Review on Mechanisms and Potential Therapeutics

The gut-brain axis refers to the bidirectional communication between the gut and brain, and regulates intestinal homeostasis and the central nervous system via neural networks and neuroendocrine, immune, and inflammatory pathways. The development of sequencing technology has evidenced the key regulatory role of the gut microbiota in several neurological disorders, including Parkinson's disease, Alzheimer's disease, and multiple sclerosis. Epilepsy is a complex disease with multiple risk factors that affect more than 50 million people worldwide; nearly 30% of patients with epilepsy cannot be controlled with drugs. Interestingly, patients with inflammatory bowel disease are more susceptible to epilepsy, and a ketogenic diet is an effective treatment for patients with intractable epilepsy. Based on these clinical facts, the role of the microbiome and the gut-brain axis in epilepsy cannot be ignored. In this review, we discuss the relationship between the gut microbiota and epilepsy, summarize the possible pathogenic mechanisms of epilepsy from the perspective of the microbiota gut-brain axis, and discuss novel therapies targeting the gut microbiota. A better understanding of the role of the microbiota in the gut-brain axis, especially the intestinal one, would help investigate the mechanism, diagnosis, prognosis evaluation, and treatment of intractable epilepsy.

The opioid antagonist naltrexone decreases seizure-like activity in genetic and chemically induced epilepsy models

OBJECTIVE

A significant number of epileptic patients fail to respond to available anticonvulsive medications. To find new anticonvulsive medications, we evaluated FDA-approved drugs not known to be anticonvulsants. Using zebrafish larvae as an initial model system, we found that the opioid antagonist naltrexone exhibited an anticonvulsant effect. We validated this effect in three other epilepsy models and present naltrexone as a promising anticonvulsive candidate.

METHODS

Candidate anticonvulsant drugs, determined by our prior transcriptomics analysis of hippocampal tissue, were evaluated in a larval zebrafish model of human Dravet syndrome (scn1Lab mutants), in wild-type zebrafish larvae treated with the pro-convulsant drug pentylenetetrazole (PTZ), in wild-type C57bl/6J acute brain slices exposed to PTZ, and in wild-type mice treated with PTZ in vivo. Abnormal locomotion was determined behaviorally in zebrafish and mice and by field potential in neocortex layer IV/V and CA1 stratum pyramidale in the hippocampus.

RESULTS

The opioid antagonist naltrexone decreased abnormal locomotion in the larval zebrafish model of human Dravet syndrome (scn1Lab mutants) and wild-type larvae treated with the pro-convulsant drug PTZ. Naltrexone also decreased seizure-like events in acute brain slices of wild-type mice, and the duration and number of seizures in adult mice injected with PTZ.

SIGNIFICANCE

Our data reveal that naltrexone has anticonvulsive properties and is a candidate drug for seizure treatment.

Molecular Chaperones and miRNAs in Epilepsy: Pathogenic Implications and Therapeutic Prospects

Epilepsy is a pathologic condition with high prevalence and devastating consequences for the patient and its entourage. Means for accurate diagnosis of type, patient monitoring for predicting seizures and follow up, and efficacious treatment are desperately needed. To improve this adverse outcome, miRNAs and the chaperone system (CS) are promising targets to understand pathogenic mechanisms and for developing theranostics applications. miRNAs implicated in conditions known or suspected to favor seizures such as neuroinflammation, to promote epileptic tolerance and neuronal survival, to regulate seizures, and others showing variations in expression levels related to seizures are promising candidates as useful biomarkers for diagnosis and patient monitoring, and as targets for developing novel therapies. Components of the CS are also promising as biomarkers and as therapeutic targets, since they participate in epileptogenic pathways and in cytoprotective mechanisms in various epileptogenic brain areas, even if what they do and how is not yet clear. The data in this review should help in the identification of molecular targets among the discussed miRNAs and CS components for research aiming at understanding epileptogenic mechanisms and, subsequently, develop means for predicting/preventing seizures and treating the disease.

Evidences for a Role of Gut Microbiota in Pathogenesis and Management of Epilepsy

Epilepsy as a chronic neurological disorder is characterized by recurrent, unprovoked epileptic seizures. In about half of the people who suffer from epilepsy, the root cause of the disorder is unknown. In the other cases, different factors can cause the onset of epilepsy. In recent years, the role of gut microbiota has been recognized in many neurological disorders, including epilepsy. These data are based on studies of the gut microbiota–brain axis, a relationship starting by a dysbiosis followed by an alteration of brain functions. Interestingly, epileptic patients may show signs of dysbiosis, therefore the normalization of the gut microbiota may lead to improvement of epilepsy and to greater efficacy of anticonvulsant drugs. In this descriptive review, we analyze the evidences for the role of gut microbiota in epilepsy and hypothesize a mechanism of action of these microorganisms in the pathogenesis and treatment of the disease. Human studies revealed an increased prevalence of Firmicutes in patients with refractory epilepsy. Exposure to various compounds can change microbiota composition, decreasing or exacerbating epileptic seizures. These include antibiotics, epileptic drugs, probiotics and ketogenic diet. Finally, we hypothesize that physical activity may play a role in epilepsy through the modulation of the gut microbiota.

Stereoelectroencephalography versus Subdural Electrode Implantation to Determine Whether Patients with Drug-resistant Epilepsy Are Candidates for Epilepsy Surgery

Epilepsy is a chronic condition that affects about 50 million individuals worldwide. While its challenges are profound, there are increasing instances where antiepileptic drugs (AEDs) fail to provide relief to epileptic manifestations. For these pharmacoresistant cases, epilepsy surgery often is an effective route for treatment. However, the complexity and challenges associated with presurgical evaluations have prevented more widespread utilization of epilepsy surgery in pharmacoresistant cases. While preliminary work-ups and non-invasive diagnostic imaging have allowed for limited identification of the epileptogenic zone (EZ), there is yet to be an established pre-determined algorithm for surgical evaluation of patients with epilepsy. However, two modalities are currently being used for localization of the EZ and in determining candidates for surgery: stereoelectroencephalography (SEEG) and subdural electrodes (SDEs). SDE has been used in the United States for decades; however, SEEG now provides a less invasive option for mapping brain regions. We seek to address which intracranial monitoring technique is superior. Through a review of the outcomes of various clinical studies, SEEG was found to have greater safety and efficiency benefits than SDE, such as lower morbidity rates, lower prevalence of neurological deficits, and shorter recovery times. Moreover, SEEG was also found to have further functional benefits by allowing for deeper targeting of cerebral tissue along with bilateral hemispheric monitoring. This has led to increased rates of seizure freedom and control among SEEG patients. Nevertheless, further studies on the limitations and advancements of SEEG and SDE are still required to provide a more comprehensive understanding regarding their application.

Synaptic Reshaping and Neuronal Outcomes in the Temporal Lobe Epilepsy

Temporal lobe epilepsy (TLE) is one of the most common types of focal epilepsy, characterized by recurrent spontaneous seizures originating in the temporal lobe(s), with mesial TLE (mTLE) as the worst form of TLE, often associated with hippocampal sclerosis. Abnormal epileptiform discharges are the result, among others, of altered cell-to-cell communication in both chemical and electrical transmissions. Current knowledge about the neurobiology of TLE in human patients emerges from pathological studies of biopsy specimens isolated from the epileptogenic zone or, in a few more recent investigations, from living subjects using positron emission tomography (PET). To overcome limitations related to the use of human tissue, animal models are of great help as they allow the selection of homogeneous samples still presenting a more various scenario of the epileptic syndrome, the presence of a comparable control group, and the availability of a greater amount of tissue for in vitro/ex vivo investigations. This review provides an overview of the structural and functional alterations of synaptic connections in the brain of TLE/mTLE patients and animal models.

Clinical Characteristics of BRAF V600E Gene Mutation in Patients of Epilepsy-Associated Brain Tumor: a Meta-analysis

Epilepsy-associated brain tumors (EATs) are usually slow-growing, with seizures as the primary and most dominant symptom. BRAF (v-raf murine sarcoma viral oncogene homolog B1) gene mutations have been found in several subsets of EATs; the V600E mutation is currently believed to contribute to the intrinsic epileptogenicity and tumor growth. However, the relationship between BRAF V600E gene mutation and clinical characteristics in EAT patients is not clear. In this study, we aimed to systematically review the frequency of BRAF V600E gene mutation, as well as the relationship between BRAF V600E gene mutation and clinical characteristics, which may help with the diagnosis and treatment of EATs. Cochrane Library, PubMed, Embase, CNKI, WanFang Data, CQVIP, and SinoMed databases were searched up to October 2020 to identify peer-reviewed human studies on assessing the relationship between BRAF V600E gene mutations and clinical characteristics in EATs. The following data were calculated: the frequency of BRAF V600E mutation and clinical feature comparison between BRAF V600E mutations and wild type in EATs, such as gender, age of seizure onset, duration of epilepsy, location of tumors, and Engel outcome. A total of 12 articles were included in the analysis. Five hundred and nine patients with epilepsy-associated brain tumors were screened for the BRAF V600E gene mutation. Among them, 193 patients had the BRAF V600E mutation (34.06%, 95% CI = 0.25 to 0.43). The subgroup analyses of BRAF V600E mutation showed positive frequency of 44.76% (95% CI = 0.36 to 0.54) in ganglioglioma, 24.75% (95% CI = 0.14 to 0.37) in gysembryoplastic neuroepithelial tumor, 2.15% (95% CI = 0 to 0.19) in angiocentric glioma, and 50.16% (95% CI = 0.33 to 0.68) in pleomorphic xanthoastrocytoma. Compared with the overall frequency, the BRAF V600E positive frequency in ganglioglioma was significantly higher (P = 0.0283). We also found that BRAF V600E gene mutation was significantly associated with age at seizure onset (MD = -2.37; 95% CI = -4.33 to -0.41; P = 0.02). There was no statistical difference between BRAF V600E mutations and wild type in gender, duration of epilepsy, tumor site, and Engel outcome comparison. In conclusion, our updated and comprehensive meta-analysis based on a large number of clinical data demonstrated that BRAF V600E mutation is a specific biomarker and could be a pharmacological target for ganglioglioma patients and an exclusion diagnostic criterion for angiocentric glioma. This meta-analysis suggested the critical role of BRAF V600E mutation in the occurrence and development of EATs. Our findings help to elucidate the progression mechanisms in EATs and develop future therapeutic strategies for EATs.

Intranasal drug delivery: opportunities and toxicologic challenges during drug development

Over the past 10 years, the interest in intranasal drug delivery in pharmaceutical R&D has increased. This review article summarises information on intranasal administration for local and systemic delivery, as well as for CNS indications. Nasal delivery offers many advantages over standard systemic delivery systems, such as its non-invasive character, a fast onset of action and in many cases reduced side effects due to a more targeted delivery. There are still formulation limitations and toxicological aspects to be optimised. Intranasal drug delivery in the field of drug development is an interesting delivery route for the treatment of neurological disorders. Systemic approaches often fail to efficiently supply the CNS with drugs. This review paper describes the anatomical, histological and physiological basis and summarises currently approved drugs for administration via intranasal delivery. Further, the review focuses on toxicological considerations of intranasally applied compounds and discusses formulation aspects that need to be considered for drug development.