Epilepsy & Behavior

Background and PurposeWhile the idiopathic generalized epilepsy (IGE) comprise around one fifth of all epilepsy, the pathogenesis of it is largely unknown. Previous studies identified cognitive deficits in IGE patients, nevertheless, whether (and how) the brain structure and functional connectivity (FC) reflect these deficits remains underexplored. Here, we aim to find structural and FC differences in cognitively impaired IGE patients. Materials and MethodsWe recruited 36 IGE patients and 49 matched healthy controls (HC) in this cross-sectional study. All participants underwent structural and resting-state fMRI (rs-fMRI) scanning with a 3 Tesla MRI. Voxel-based morphometric analysis (VBM) was used to assessed structure differences, and seed-based analysis of rs-fMRI was used to examine FC. We examined the cognitive performance of patient with MoCA (Montreal Cognitive Assessment), grouped them into high (HMoCA, >25) and low (LMoCA, [&le;]25) group, and further examined the brain structural changes functional changes in each group. ResultsIGE patients showed right significant decrease in cerebellar gray matter volume (GMV), negatively correlating with the disease duration (r=-0.542, p=0.001), and increase in the left dorsolateral superior frontal gyrus GMV. Right cerebellum showed increased connectivity to the precuneus and angular gyrus, decreased connectivity to the postcentral gyrus and Rolandic operculum. Surprisingly, we found that LMoCA IGE patients (with more cognitive deficits) had increased right nucleus accumbens (NAc) GMV (t = -4.413, p < 0.001) and FC and a stronger NAc - prefrontal cortex FC (t = -2.683, p = 0.013), in comparison with the patients with high MoCA. ConclusionsCognitive impairment in IGE patients is linked to the NAc structural changes and NAc-prefrontal circuit alterations. These results provide novel circuit-level insights into understanding the cognitive impairment in IGE patients, contributing to revealing the pathophysiological mechanisms of IGE.

Sudden unexpected death in Epilepsy (SUDEP) is the leading cause of death in patients with Epilepsy. Although SUDEP results from cardiorespiratory arrest, its underlying mechanisms are poorly understood. Considering the significant association between stress-related disorders and Epilepsy, we hypothesized that stress exaggerates autonomic reflexes critical in cardiorespiratory function and that these exaggerated reflexes increase susceptibility to SUDEP. Experiments were performed using a novel mouse model of SUDEP where chronic hyperactivity of central corticotropin-releasing hormone (CRH) neurons (Kcc2/Crh) predisposes mice to SUDEP in the weeks following seizure induction based on the ventral intrahippocampal kainate (vIHKA) model of chronic Epilepsy. In our study, the vIHKA model was employed in both wild-type (WT) and Kcc2/Crh mice while they were monitored with EEG and ECG using in vivo telemetry and underwent terminal autonomic reflex testing at time points when mortality peaked and plateaued. A resting tachycardia developed by one week following vIHKA injection but subsided by day 30 in both WT and Kcc2/Crh mice. During spontaneous seizures, Kcc2/Crh mice had more pronounced reflex-like ictal bradycardias compared to WT controls that notably occurred prior ([~]10 sec) to seizure termination. vIHKA injection promoted time-dependent exaggeration of autonomic reflexes, with Kcc2/Crh mice exhibiting robust autonomic disturbances compared to WT controls, including a pronounced serotonin-mediated Bezold Jarisch reflex. Taken together, our findings indicate that increased autonomic disturbance burden parallels time-dependent SUDEP susceptibility in mice with hyperactive stress circuits.

Objective: The postictal state is a major yet underrecognised component of epilepsy burden. We aimed to develop a structured patient-reported instrument to quantify postictal recovery, characterise its multidimensional burden and identify demographic, clinical, psychiatric and treatment-related factors associated with postictal severity and duration. Methods: We conducted a prospective, single-centre observational cohort study (Timone Hospital, Marseille, February 2025 - March 2026). Consecutive patients aged >=15 years admitted for scalp or stereo-EEG video-monitoring were included. Patients completed the Postictal Recovery Scale (PRS), an 11-domain questionnaire assessing fatigue, mood, sensory, motor, language, orientation, time perception and postictal amnesia. Items were rated from 0 (severe impairment) to 3 (no symptoms), yielding a total score of 0-33. Internal consistency was assessed using Cronbach alpha. Associations between PRS scores, subjective postictal duration and covariates were analysed using group comparisons, correlations and regression models. Results: Of 107 enrolled patients, 96 were included. PRS showed good internal consistency (Cronbach alpha; = 0.79). 96% of patients reported experiencing postictal symptoms, with fatigue (80%) and postictal amnesia (79%) being the most frequent and severe manifestations. Recovery exceeded one hour in 21% of patients. Greater postictal impairment was associated with higher interictal anxiety (Spearman {rho} = -0.32, p = 0.0018) and depressive symptoms (Spearman {rho} = -0.40, p = 0.0001), whereas demographic, epilepsy-related and treatment variables showed no significant associations. Altered postictal time perception was reported by 40% of patients and was associated with disorientation, but not psychiatric symptoms. Subjective postictal duration was longer than subjective ictal duration (Wilcoxon test, p < 0.0001). Significance: The postictal state is a frequent and multidimensional patient-reported experience. Greater postictal severity, particularly concerning anxiety and depression, is associated with interictal psychiatric comorbidity, while altered temporal experience emerges as a distinct dimension of postictal dysfunction. These findings support integrating postictal measures into clinical practice and trials.

Epilepsy is one of the most prevalent neurological diseases, with 25-33% of patients developing drug-resistant epilepsy (DRE). The precise etiology of DRE remains unidentified. Recent studies have revealed an increase in tetraploid astrocytes in drug-resistant temporal lobe epilepsy (DR-TLE), a common subtype of DRE. This study aims to characterize the function of tetraploid astrocytes in the brain of subjects without central nervous system diseases and in DR-TLE. Cortical samples adjacent to the epileptogenic zone were obtained from DR-TLE patients undergoing resective neurosurgery and from postmortem donors without neurodegenerative, neurological, or psychiatric disorders. Tetraploid astrocytes were identified using the astrocytic marker NDRG2, and their functional characterization was assessed by evaluating markers of metabolism (ALDH1L1), transport (SOX9), electric function (NF1A), or reactive astrocytes (NF{kappa}B p65 and pSTAT3), via immunostaining followed by flow cytometry. Tetraploid astrocytes expressed all functional markers tested. The percentage of tetraploid astrocytes expressing ALDH1L1 or SOX9 was significantly increased in DR-TLE with respect to controls, whereas NF1A remained unchanged. Inflammatory markers pSTAT3 and NF{kappa}B p65 showed an upward trend in 4C astrocytes. In contrast, diploid (2C) astrocytes expressing these markers were reduced in DR-TLE, suggesting a functional shift toward polyploid cells in the DR-TLE cortex. Our findings suggest the preservation of markers of metabolism, transport and electric function in tetraploid astrocytes in physiological conditions and in DR-TLE patients. Moreover, the astrocytes with metabolic and transporter markers were significantly increased in DR-TLE. These findings point to tetraploid astrocytes as potential contributors to DR-TLE mechanisms.

ObjectiveMany patients develop post-traumatic epilepsy (PTE). Post-traumatic epileptogenesis has been carefully studied in rodents, but the time course of epileptogenesis is correlated to brain size, raising the possibility that large animal models will provide more translatable data regarding epileptogenesis. Here, we use our large-brained model to describe the development, rate, and seizure semiology of PTE. MethodsAdult male and female swine received bilateral cortical impact (N=16) or sham surgery (N=9) and were screened for convulsions via video EEG for up to one year. PTE was defined as 2 seizures after 1 week post-injury. ResultsNine out of sixteen pig (56%) receiving bilateral cortical impact developed PTE, with an average latent period of 6.6 months ({+/-} 3.9, SD). Seizure began focally, sometimes with motor onset including automatisms (lip smacking, yawning) and sometimes nonmotor (freezing) before becoming generalized, with tonic-clonic or tonic convulsions. Most pigs had a period of post-ictal stillness (nonmotor) after the convulsions. Temporary incoordination occurred both pre- and post-ictal. We defined a library differentiating peri-ictal behaviors (N = 27) from rhythmic/odd behaviors typical in healthy pigs (N = 11). Pigs with PTE had an average of 5.6 behaviors per seizure, with a max of 22 behaviors in a seizure. The longest seizure was 7.9 minutes. For seizures comprised of multiple convulsive episodes, the first convulsion had a greater number of peri-ictal behaviors than subsequent convulsions (P < 0.02). The array of peri-ictal behaviors displayed was pig-specific, with many behaviors consistently observed across seizures. The overall seizure frequency was 0.43/day. SignificanceThis large-brain model of PTE exhibits a prolonged period of epileptogenesis, a substantial rate of PTE, and an expansive repertoire of ictal behaviors. This first description of semiology in this species will serve as a guide for other porcine epilepsy models. Biofidelic models of PTE are expected to increase our understanding of the pathophysiology of post-traumatic epileptogenesis and to identify and test therapeutics that translate into human patients. Key PointsO_LIThe average time from bilateral cortical impact to post-traumatic epilepsy is 6 months. C_LIO_LISwine with post-traumatic epilepsy display an array of specific behaviors distinct from pigs without post-traumatic epilepsy. C_LIO_LIPigs have individualized stereotypical behaviors around convulsions and can have many convulsions within a seizure. C_LIO_LIThough convulsions last a few seconds, the entire seizure, with the associated peri-ictal behaviors, lasts up to 7.9 minutes. C_LI

Contactin-associated protein-like 2 (CNTNAP2) is a transmembrane protein that mediates neuron-glia interactions and regulates dendritic spine growth and neuronal migration. Mutations in the CNTNAP2 gene are linked to autism and epilepsy. Younger Cntnap2 KO mice mimic autism phenotypes, while older mice are a model for epilepsy. Thus, comparing behavioral phenotypes across different ages is needed to better understand the age dependent development of disordered brain networks in Cntnap2 mutants. Male and female Cntnap2 KO and WT controls were tested across different age groups (4, 5, 7, 9, and [~]11 months) using digging, stimulus (reactivity), and nesting assays. Older Cntnap2 KO mice (7, 9, and [~]11 months) showed a significant increase in home cage reactivity (stimulus) assay compared to younger mice at 4 and 5 months of age. Similar trends were observed in male and female Cntnap2 KO mice. No significant differences were observed in WT controls. A significant difference in digging assay was observed in KO female mice between younger (4 month) and older mice post nest removal. An age-dependent significant reduction in nesting behavior was observed in female KO mice; however, no difference was observed in the WT controls. Immunohistochemical analysis showed age dependent change interneuron and microglial network in Cntnap2 KO mice. Our findings suggest disruption in home cage behavior and reactivity in older pre-epileptic Cntnap2 KO mice indicating an age-dependent network alteration and behavior deficits. Significance StatementThis study investigates the age-dependent behavioral changes in Cntnap2 KO mice due to underlying changes in the neuronal network. It has been shown that younger Cntnap2 KO mice display autistic behaviors and that older Cntnap2 KO mice have epilepsy, but it is unknown how behavior is affected during the intervening period of epileptogenesis. We find that female Cntnap2 KO mice at 11 months of age have increased reactivity and decreased motor activity compared to younger age groups, whereas WT mice show no relationship between age and behavior. Overall, the loss of Cntnap2 alters behavior in an age-dependent and sex-specific manner, indicating progressive dysregulation of the neuronal network.

BackgroundPersons with epilepsy are at increased risk of depression/anxiety. Older antiseizure medications (ASMs) had drug-drug interactions that complicated pharmacotherapy of depression/anxiety; newer ASMs lack this drawback but can have psychiatric side effects. Anxiety/depression are increasingly recognized and treated pharmacologically. We hypothesized that the likelihood of treatment with selective serotonin uptake inhibitors (SSRI) would have increased in adult-onset epilepsy when prescription habits shifted towards newer ASMs. MethodsWe linked national health registers and included 28569 persons with epilepsy incident in 2006-2020 and 68509 age- and sex matched controls. We assessed the risk of starting SSRI treatment compared to age- and sex-matched controls across three incidence periods: 2006-2010, 2011-2015, and 2016-2020. Cox regression was used to estimate adjusted hazard ratios (HRs), and subgroup analyses explored age, sex, and comorbidities. Specialist psychiatric care was also assessed as a measure of more severe depression. Analysis including persons with SSRI-use before the epilepsy diagnosis were used for sensitivity analyses. FindingsPersons with epilepsy had higher risks of starting SSRIs compared to controls; 1986/9561 (20.8%) received SSRI during follow-up after epilepsy in 2006-2010 and 2020/9165 (22.0%) in 2016-2020; adjusted HRs were 1.92 (95%CI:1.79 - 2.06) in 2006-2010, 1.84 (95%CI:1.72-1.97) in 2011-2015, and 1.81 (95%CI:1.69 - 1.94) in 2016-2020. Among individuals aged 18-30 years at their epilepsy diagnosis, the proportion receiving SSRIs remained the same between the first and last calendar periods (18.2%). Because of increased treatment of controls, the adjusted HRs of SSRI-treatment decreased from 2.33, (95% CI:1.96 - 2.78) to 1.63, (95% CI 1.39 to 1.91). The HR of specialist psychiatric care was not significantly different between the time periods. Most comorbidities were consistently associated with increased likelihood of SSRI treatment, whereas intellectual disability decreased the likelihood in some periods. InterpretationWe found no evidence of overall increased SSRI initiation or psychiatric care after the shift to newer ASMs. Person with epilepsy remain more likely to receive SSRI treatment, but probably not to a level matching the higher prevalence of depression. Increased SSRI treatment of younger age adults has not been matched by increased treatment of young adults with epilepsy. This suggests a potentially widening treatment gap and a need for increased recognition of depression in young adults with epilepsy. FundingSwedish Research Council (2023-02816), Swedish state through the ALF-agreement (ALFGBG-1006343), Knut och Ragnvi Jacobsson foundation, Swedish Society for Medical Research (S18-0040), Swedish Society of medicine (SLS-881501), Epilepsifonden, Rune och Ulla Amlovs stiftelse.

BACKGROUND AND OBJECTIVESPatients with epilepsy (PWE), especially temporal lobe epilepsy (TLE), experience impaired memory for personally experienced events. However, current assessments of episodic memory are limited in their ecological validity with a potential to miss detection of subtle cognitive decline. We conducted an exploratory study to determine whether a naturalistic film-viewing task with open-ended spoken recall could detect memory differences between TLE patients and healthy controls (HCs). METHODSTLE patients (ages 18-60, fluent in English, not legally blind) were recruited from a Level 4 Epilepsy Center (2018-2024). TLE diagnosis was based on seizure semiology, MRI Brain, and EEG. TLE patients scored [&ge;]22/30 on the Montreal Cognitive Assessment (MOCA); HCs scored [&ge;]26/30. Subjects watched 6 short films and then freely recalled film details. Spoken responses were recorded, transcribed, segmented, and scored for film- and event-level recall. Recall order was assessed using the Damerau-Levenshtein distance. Semantic and causal centrality were quantified using sentence embeddings and rater-identified causal links, respectively. Beta regression with cluster-robust standard errors assessed group and centrality effects on recall probability. Beta regression evaluated the influence of age, MOCA, and testing platform on sequence recall error. RESULTSWe recruited 51 subjects (27 TLEs; 24 HCs, 70.1% F, mean 29.9 {+/-}8.3 years). TLE patients and HCs showed similar recall of films (HC 89% {+/-}11% vs TLE 88% {+/-}18%, p = 0.54), coarse events (HC 50% {+/-}16% vs TLE 44% {+/-}18%, p = 0.19) and fine events (HC 25%{+/-}10% vs. TLE 22%{+/-}12%, p=0.17). Both groups recalled high causal centrality events better. For coarse event sequence recall, TLE patients showed a numerical trend toward greater sequence errors compared to HCs (HC 10.8% {+/-} 10.5% vs. TLE 19.5% {+/-} 18%, p = 0.06), although this difference did not reach statistical significance. However, TLE patients showed significantly greater fine event sequence errors at recall than HCs (HC 15% {+/-}13% vs 23% {+/-}18%, p = 0.02, Hedges g = 0.85, Cliffs {delta} = 0.51), with RTLE demonstrating more sequence errors than HCs (15%{+/-}13 vs. 29%{+/-}21% p = 0.021) Age, education, MOCA, and performance on standard verbal and visual memory tasks were unrelated to film, event, and sequence recall performance. DISCUSSIONWe demonstrate that a short film task with spontaneous spoken recall can identify sequence memory impairment in TLE patients despite intact film- and event-level recall. Sequence memory may represent a subtle manifestation of memory impairment that is not detected by standard cognitive testing. Key PointsO_LIWe asked whether a naturalistic film recall task could detect episodic memory impairment in a temporal lobe epilepsy cohort. C_LIO_LIPatients with temporal lobe epilepsy showed comparable film and event recall compared to healthy controls but were found to have impaired sequence memory. C_LIO_LISequential memory for temporal order is an overlooked aspect of episodic memory that may detect subtle memory decline. C_LI

Maintaining electrical signaling homeostasis in the human neocortex relies on cell-type specific gene expression programs. However, when these programs are disrupted, the resulting imbalances can contribute to the pathogenesis of neurological disorders like epilepsy. Genetic factors are particularly implicated in a specific subtype of epilepsy known as refractory epilepsy or drug-resistant epilepsy (RE/DRE). This study shows the main results of the analysis of single cell transcriptomics for five pediatric RE patients in Colombia. A total of six samples obtained through surgical resection were analyzed by single-nuclei RNA sequencing (snRNA-seq). The genome of one patient was sequenced using high fidelity long-read sequencing. Functional enrichment of differentially expressed genes (DEGs) revealed glia-driven dysregulation of synaptic signaling, impaired glial-neuronal communication, and altered expression of genes related to neurotransmitter transport and calcium signaling. Activation of taste receptors in neurons was associated with neuroinflammatory processes. Structural variants were detected in genes associated with alterations of expression in specific cell types. This new data resource increases the diversity of information needed to develop new strategies for diagnosis of refractory epilepsy.

ObjectiveBrain infection is an underrecognized global cause of epilepsy due to the ensuing neuroinflammation and neurological damage. Immune system response, including underlying neuroinflammation, is dynamically shaped by the intestinal microbiome. In experimental rodent epilepsy models, seizure burden and antiseizure medication (ASM) activity can be dramatically influenced by gut dysbiosis, including in the Theilers murine encephalomyelitis virus (TMEV) infection model of acute symptomatic seizures and long-term epilepsy. We previously demonstrated that experimentally induced gut dysbiosis via repeated antibiotic administration alters seizure burden and carbamazepine (CBZ) anticonvulsant activity in this model (1). However, whether dysbiosis and CBZ differentially shape neuropathological damage and neuroinflammation following TMEV infection was not reported. MethodsHere, we extended our earlier study to quantify the extent to which antibiotic-induced gut dysbiosis and repeated CBZ administration during TMEV infection altered the severity of acute neuropathology. Hippocampal tissue was analyzed 7 days post-infection using quantitative immunofluorescence to assess neuronal death, microglial and astroglial reactivity, and neuronal proliferation across CA1, CA3, and dentate gyrus (DG) subregions. ResultsDysbiosis markedly exacerbated hippocampal neurodegeneration and gliosis, accompanied by increased glial proliferation, whereas CBZ administration reversed these effects in a hippocampal region-dependent manner. Collectively, these findings demonstrate that the gut microbiome primes hippocampal neuroimmune responses to viral infection-induced acute seizures and modifies associated neuropathology in a hippocampal region-specific manner. SignificanceThis work identifies the gut-brain axis as a critical determinant of neuroinflammatory damage after infection-induced symptomatic seizures, highlighting the gut microbiome as a potential therapeutic target to alleviate the worldwide epilepsy burden. HighlightsO_LIExperimentally-evoked gut dysbiosis exacerbates hippocampal neurodegeneration after brain viral infection. C_LIO_LIExperimentally-evoked gut dysbiosis increases microgliosis and glial proliferation after brain viral infection. C_LIO_LICarbamazepine reversed dysbiosis-induced neuroinflammation and neurodegeneration. C_LIO_LIExperimentally-evoked gut dysbiosis differentially modulates glial response in the dentate gyrus. C_LI

BackgroundTemporal lobe epilepsy (TLE) often originates from focal hippocampal injury but progressively evolves into a bilateral epileptic network engaging both hippocampi and distributed cortical regions. A mechanistic understanding of how this network emerges, and whether early perturbation of specific nodes can alter its trajectory, is essential for developing network-level therapeutic strategies. ObjectiveWe used a kainate-induced rodent model of TLE to (1) characterize the spatiotemporal emergence of epileptic discharges during the latent phase, (2) determine how bilaterally synchronized events develop, and (3) test whether transient chemogenetic silencing of either the ipsilateral epileptogenic focus (EF) or the contralateral hippocampus (CH) modifies large-scale epileptogenesis. MethodsFreely moving mice were implanted with multi-site electrodes spanning bilateral hippocampal subfields (dentate gyrus, CA1, subiculum) and cortical regions (M2, Cg1, PrL, V1, entorhinal cortex). Longitudinal LFP recordings were performed every other day during the latent and early chronic phases following KA or saline injection. DREADD-based chemogenetic inhibition of glutamatergic neurons was applied between days 2-7 post-KA. Epileptiform events were quantified via spike rates, waveform metrics, high-frequency oscillations (HFOs), and short-latency interregional co-spiking ResultsEarly after KA, epileptic spiking emerged locally in the ipsilateral dentate gyrus and progressively organized into HFO-coupled discharges. Contralateral hippocampal recruitment followed a distinctive biphasic time course, characterized by transient early activation, subsequent suppression, and later re-emergence with increasing bilateral coactivation. Cortical regions gradually developed higher spike rates and enhanced DG-related co-spiking, indicating large-scale network integration. Ipsilateral silencing modified local spike composition but did not prevent global network progression, whereas contralateral silencing accelerated ipsilateral epileptogenesis and strengthened pathological HFO expression. ConclusionEpileptogenesis in the KA model reflects a transition from a focal hippocampal insult to a resilient, bilateral cortico-hippocampal network. Targeting a single hippocampal node--even at early latent stages--is insufficient to halt this progression, highlighting the need for network-level therapeutic strategies. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=116 SRC="FIGDIR/small/701979v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@171797dorg.highwire.dtl.DTLVardef@df13d3org.highwire.dtl.DTLVardef@18e9594org.highwire.dtl.DTLVardef@1fe68f8_HPS_FORMAT_FIGEXP M_FIG C_FIG

ObjectivesWith the expected demographic shift toward those [&ge;]65 years of age in the United States, late-onset epilepsy (LOE) poses a significant public health issue, yet it has been historically understudied. We are undertaking an effort in the Epilepsy-Cog study to pool individual participant data from six US-based prospective cohort studies. In this paper, we outline the process for ascertaining epilepsy, harmonizing, and pooling individual participant data across the six cohorts. MethodsThe Epilepsy-Cog study includes individual participant data from six US-based longitudinal cohort studies: ARIC, CHS, MESA, NOMAS, REGARDS, and WHICAP. In all cohorts except NOMAS, prevalent and incident epilepsy were ascertained using Medicare claims-based algorithms. In NOMAS, epilepsy cases were identified through cohort-based reporting and medical record review. To perform cross-cohort harmonization of variables, we used the lowest common denominator approach, assigning response categories or value levels in common across all cohorts. ResultsFrom a total of 68,544 participants across six cohorts, 43,753 participants met eligibility criteria for Epilepsy-Cog. Among them, we identified 551 (1.3%) participants with prevalent epilepsy and 1,500 (3.4%) participants with incident epilepsy. We have harmonized demographic characteristics, health behaviors, vascular risk factors (VRFs), one genetic variable, medication use, subjective health status measures, incident events, and cause-of-death variables. ConclusionThe Epilepsy-Cog pooled cohort of 43,753 participants with and without epilepsy, combined with harmonized demographic, VRFs, and event data, offers a unique resource to yield new insights into LOE.

Ferroptosis is a form of non-apoptotic cell death in which iron catalyzes the formation of reactive oxygen species, leading to lipid peroxidation. Experimentally, this process has recently been associated with seizures based on the increased levels of specific markers (4-hydroxynonenal and malondialdehyde) in the brain and plasma. Clinically, iron deposits have been identified in resected tissue from patients with refractory temporal lobe epilepsy. Quantitative susceptibility mapping (QSM) offers an opportunity to detect these accumulations in vivo. In this study, we investigated how pilocarpine-induced status epilepticus contributes to the generation of iron deposits in diverse cerebral regions and whether QSM can detect these deposits longitudinally. We scanned 14 animals (n=10 experimental; n=4 control) at five different time points (pre-status epilepticus induction and 1, 7, 14, 21 days post-induction) using QSM. We identified iron deposits in the caudate putamen, hippocampus, thalamus, and primary somatosensory cortex of experimental animals, which is consistent with histological findings. The initial size of the hippocampal iron deposits significantly increased over the following weeks. None of these effects was observed in the control animals. The presence of cerebral iron depositions in an animal model of pilocarpine-induced status epilepticus suggests that ferroptosis may be involved in the onset, development, and progression of spontaneous recurrent seizures. Furthermore, non-invasive, longitudinal in vivo mapping of brain iron deposits could be a potential imaging marker in neurological disorders such as epilepsy. Future experiments will be required to determine the origin of the iron and avoid its progressive accumulation. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=70 SRC="FIGDIR/small/712677v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@14abf67org.highwire.dtl.DTLVardef@5c08fborg.highwire.dtl.DTLVardef@51c40forg.highwire.dtl.DTLVardef@1eb5f9_HPS_FORMAT_FIGEXP M_FIG C_FIG

About half of patients who undergo epilepsy surgery for drug-resistant epilepsy have seizure recurrence, supporting the need for approaches that more accurately identify the epileptogenic zone, defined as the brain areas whose removal causes cessation of seizures. Altered network connectivity has emerged as a candidate biomarker of the epileptogenic zone, but how connectivity is altered in the epileptogenic zone remains uncertain, with prior studies reporting inconsistent results. We hypothesized that a difference in intrinsic versus extrinsic connectivity of the epileptogenic zone may explain prior discrepant findings. We studied a multicenter cohort of adult and pediatric patients who underwent intracranial EEG recording and brain stimulation as part of epilepsy surgery planning. We measured spontaneous connectivity using Pearson correlation and perturbational connectivity using stimulation evoked potentials, modeling the connectivity according to the location of contacts in relation to the seizure onset zone (SOZ) while controlling for inter-electrode distance. We analyzed 79 patients (37 adults, 42 children). For both adult and pediatric patients, resting connectivity was higher within compared to outside the SOZ, but resting connectivity between SOZ and non-SOZ contacts was reduced. Stimulation connectivity followed a similar pattern, with elevated within-SOZ connectivity but reduced connectivity between SOZ and non-SOZ. The results support the hypothesis that the epileptogenic zone is disconnected from the rest of the brain but intrinsically hyperconnected. This result helps reconcile prior inconsistencies across studies, aligns with the results of basic science studies, and suggests that future translational work should model this heterogeneous pattern to increase the yield of using connectivity to localize the epileptogenic zone.

ImportanceTracking and predicting seizure frequency in patients with epilepsy is important for prognostication and therapy management. Interictal spikes have been proposed as a biomarker of seizure burden, but their association with seizure frequency has not been well quantified across epilepsy subtypes. ObjectiveTo measure the association between spike rate and seizure frequency and how this varies by epilepsy subtype. Design, Setting and ParticipantsWe studied 3,614 consecutive routine outpatient EEGs from 3,245 patients with epilepsy. A validated automated detector (SpikeNet2) estimated spike frequency. Validated large language models performed natural language processing on outpatient clinic notes to extract seizure frequency and epilepsy subtype. Main Outcomes and MeasuresSpearman correlation between spike frequency (spikes/hour) and seizure frequency (seizures/month) for all patients with epilepsy and for patients with generalized epilepsy, temporal lobe epilepsy, and frontal lobe epilepsy. ResultsOverall, spike frequency was modestly associated with seizure frequency (N = 3,245, {rho} = 0.11, p < 0.001). Significant positive associations were observed in generalized epilepsy (N = 625, {rho} = 0.23, Bonferroni-adjusted p < 0.001) and temporal lobe epilepsy (N = 834, {rho} = 0.12, p = 0.0013), but not in frontal lobe epilepsy (N = 263, {rho} = 0.11, p = 0.22). Conclusions and RelevanceIn this large outpatient cohort, higher interictal spike rates on routine EEG were associated with higher seizure frequencies, with the strongest relationship observed in generalized epilepsy. These associations support interictal spike rate as a quantitative EEG marker of seizure burden. Spike rate may have clinical utility for risk stratification at diagnosis and for monitoring longitudinal changes in seizure burden in response to therapy.

Interictal epileptiform discharges (IEDs) are pathological hypersynchronous bursts of electrical brain activity that occur between seizures in patients with epilepsy. IEDs are caused by transient brain states that are difficult to predict, making them a challenging neurophysiological and technological case for brain-state-dependent stimulation. Administering stimulation at IED onset may provide insight into the epileptic network and optimize neurostimulation therapies. Here, we assessed the feasibility of IED-triggered transcranial magnetic stimulation (TMS) in two children with self-limited epilepsy with centrotemporal spikes (SeLECTS), a common pediatric epilepsy in which IEDs emerge from the motor cortex. A convolutional neural network (CNN) was trained on the participants pre-recorded electroencephalography (EEG) data with IEDs annotated by an epileptologist. The CNN was integrated into an EEG-processing pipeline that classified EEG segments as "IED" or "non-IED" in real time. With this pipeline, TMS pulses were administered during IED or non-IED periods in an interleaved, randomized design. We stimulated both the motor cortex generating the IEDs and the contralateral motor cortex and tested the impact of IEDs on TMS-evoked potentials (TEPs). Our study demonstrated that TMS can be timed to IEDs and that there is a site-specific increase in TEP amplitude when stimulating during IEDs. Out of the TMS pulses aimed at an IED, 39% and 19% were successfully delivered during an IED for the two participants, respectively. For future research, we propose ways to address the methodological challenges of IED-timed TMS, enabling brain-state-dependent TMS for epilepsy research and treatment.

Background: The detection of subtle epileptogenic lesions such as focal cortical dysplasias (FCDs) is a clinical challenge in the management of drug-resistant focal epilepsy (DRFE). Ultra-high field (UHF) MRI offers increased signal-to-noise ratios and spatial resolution compared to 3Tesla (T) MRI and may improve diagnostic yield. Here, we present a 9.4T MRI cohort study of patients with DRFE. Methods: We recruited n=21 DRFE patients (with 3T-MRI findings: 2 positive, 3 equivocal, 16 negative) undergoing presurgical workup, and n=20 healthy controls for 9.4T MRI (0.8 mm isotropic MP2RAGE, slabs of 0.375 x 0.375 x 0.8 mm T2*-weighted GRE) and 3T MRI (MP2RAGE, FLAIR) acquisitions. Visual review for possible epileptogenic lesions was performed by clinical experts. For histopathologically confirmed FCD lesions, we extracted surface-based quantitative features (cortical thickness, qT1, FLAIR, T2*, and QSM values) across cortical depths and distances from the lesion centre and performed high-resolution cortical profiling of 9.4T T2* values. Results: No new epileptogenic lesions were visually identified at 9.4T in 3T MRI negative patients. In the two patients with histopathologically confirmed lesions, the FCD IIb lesions were visible with distinct qualitative and quantitative features at both field strengths. One of these FCD IIb showed a focal cortical T2* reduction at 9.4T that could here be quantified via automated cortical profiling, consistent with the previously described "black line sign". Conclusion: 9.4T MRI findings in epileptogenic lesions underlying DRFE are consistent with those on 3T MRI. While additional lesions were not identified in patients with negative 3T MRI, higher resolution T2*-weighted sequences can reveal a feature not seen at 3T: Cortical profiling of FCDs highlights the black line sign and can possibly help refine surgical or ablation targeting for some FCDs. Further optimization of UHF protocols and analysis methods on larger cohorts may reveal clinically applicable diagnostic benefits.

Susceptibility to epileptogenesis varies in humans and outbred mouse strains. We hypothesized that baseline sleep abnormalities increase susceptibility to epileptogenesis following Kainic acid (KA) and abnormal circadian rhythm or sleep homeostasis (SH) contribute to worse seizures in epilepsy-susceptible DBAs. Following EEG electrode implantation, C57 and DBA mice underwent repeated low-dose KA or saline treatment. Seizures, interictal spikes and sleep were examined over 8-weeks with continuous electroencephalography (EEG). Seizures were manually scored, and interictal spikes and sleep were analyzed using machine learning algorithms. Slow wave activity (SWA) was derived from non-rapid eye movement (NREM) sleep following Fourier transform, and SH was measured by the decay of SWA during sleep and its rise with preceding wakefulness. The impact of post-KA seizures on circadian rhythm was determined using Cosinor analysis. Seizures were longer and more frequent in KA-treated DBAs than C57s. Interictal spike were much greater in saline-treated DBAs than C57s. SWA across the 24-hours was lower in DBAs at baseline. KA treatment decreased REM and increased SWA activity in DBAs but not in C57s. Cosinor analysis revealed circadian rhythm abnormalities in DBAs but not in C57s. Seizures impaired SH in DBAs, with no increase in SWA with preceding wakefulness and a progressive loss of SWA decay during lights-on over the 8-week recording. These findings suggest that baseline sleep abnormalities, poorly adaptable circadian rhythms and impaired SH are associated with increased vulnerability to epileptogenesis. Therapies enhancing circadian rhythm and SH after an insult may be avenues to mitigate epileptogenesis in vulnerable populations. Significance StatementSusceptibility to spontaneous seizures after a central nervous system insult varies in humans as well as mouse models. The reasons behind the differential susceptibility are not entirely known. Here we show in a Kainic acid model, epilepsy susceptible DBA/2J mice have baseline sleep abnormalities and following Kainic acid treatment, these mice develop more frequent and longer seizures than the epilepsy-resistant C57BL/6 mice. We also show that the epilepsy-susceptible DBAs have abnormalities in circadian rhythm as well as sleep homeostasis measures compared to epilepsy-resistant C57s, which may be contributing to progression of epileptogenesis and worse seizures. Therapies targeted at enhancing sleep, circadian rhythms or sleep homeostasis may be avenues to mitigate development of spontaneous seizures after a central nervous system insult.

The Brahma-related gene 1 (BRG1) encodes the catalytic subunit of the SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatin remodeling complex and plays an important role in brain development. Variants in SWI/SNF components are often found in patients with epilepsy, but it is still unclear how loss of BRG1 function contributes to seizure development. In this study, we analyzed the role of Brg1 in seizure susceptibility using zebrafish models with both pharmacological inhibition or genetic reduction of Brg1. Reduced Brg1 function caused seizure-like behavior and increased neuronal activity in larvae, while basic locomotor activity was preserved. Further analyses showed reduced expression of several GABAergic system markers. In contrast, glutamatergic markers did not show major changes. These results point to a selective impairment of inhibitory signaling. When GABA levels were increased pharmacologically, seizure-like behavior was reduced. This suggests that loss of inhibitory transmission plays an important role in the observed hyperexcitability. Unbiased omics analyses also identified changes in proteins associated with vitamin B6 binding. Treatment with active vitamin B6 reduced seizure-like behavior in larvae with reduced Brg1 function. Taken together, these results indicate that Brg1 is required for proper inhibitory neurotransmission and that partial loss of Brg1 function increases seizure susceptibility. These findings may help to better understand why mutations in chromatin remodeling genes are often associated with epilepsy and could support future studies on targeted modulation of inhibitory signaling in these conditions. Significance StatementChromatin remodeling genes are often mutated in patients with epilepsy, but it is still unclear how these mutations lead to seizures. In this study, we show that reduced function of the chromatin remodeler Brg1 affects inhibitory neurotransmission by impairing the GABAergic system. This leads to increased neuronal activity and seizure-like behavior. Our results identify the chromatin remodeler Brg1 as an important regulator of inhibitory neurotransmission and seizure susceptibility, which may be important for understanding epilepsy associated with neurodevelopmental disorders.

Objective: Electrical brain stimulations (EBS) are central to epileptic network identification and functional mapping during stereo-electroencephalography (SEEG), yet stimulation frequencies remain empirical, and standardized across patients and brain regions, producing false negatives and false positives, and potentially compromising surgical outcome. We investigated theta-range EBS (7 Hz) in the temporal lobe, a prominent physiological frequency band in this region, and compared it with conventional 1-Hz and 50-Hz protocols. Methods: We analyzed 1,408 temporal EBS in 25 patients with drug-resistant epilepsy. Epileptic responses (afterdischarges, seizures) and clinical signs were assessed across the epileptic network and temporal structures (amygdala, hippocampus, neocortex, parahippocampal gyrus, white matter), and analyzed according to stimulation parameters (frequency, intensity, duration, total charge). Results: At matched intensity and duration, 7-Hz EBS were associated with a higher occurrence of afterdischarges and clinical signs than 1-Hz EBS in several temporal structures (e.g., parahippocampal epileptogenic zone: p=0.014). Effects on usual seizure induction were less consistent. Comparisons with 50 Hz showed no systematic significant differences, with responses observed at one or both frequencies depending on structure and outcome. When controlling for total charge, frequency-related differences were attenuated. Some effects were sporadically observed at both intermediate frequency and charge quantity. No adverse events occured. Significance: Theta-range stimulation modulates electrophysiological and clinical responses during SEEG mapping and may provide complementary information to conventional frequencies. These findings support exploring a broader range of stimulation frequencies, rather than relying solely on standard protocols.