Background Post-craniotomy headache is a common adverse effect of anterior temporal lobectomy. It is hypothesized that increased pain sensation may be associated with manipulation of the dura intraoperatively. To explore a potential origin, we analyzed the blood vessel and nerve bundle distribution in the mesial and lateral temporal dura of the middle cranial fossa. Methods Human temporal dura sections were immunohistochemically stained for α-smooth muscle actin to visualize blood vessels and/or neurofilament protein to detect nerve bundles. Immunoreactive blood vessels and nerve bundles were counted by a blinded observer in a random order. Statistical analysis was conducted using a linear mixed model. An intraclass correlation coefficient (ICC) was calculated to assess inter-observer reliability. Results The number of blood vessels/cm in the temporo-mesial dura was about 57% higher than that in the temporo-lateral dura (n = 4; 29.9 (95% confidence interval (CI) [23.3; 36.5]) vs 18.9 (95% CI [17.4; 20.3]), p < 0.001). Similarly, the number of nerve bundles/cm in the temporo-mesial dura was almost 4 times higher than that in the temporo-lateral (n = 4; 7.5 (95% CI [5.3; 9.6]) vs 2.0 (95% CI [1.5; 2.5]), p < 0.001). Double-stained sections (n = 6) revealed that neurovascular structures were frequently in close proximity. ICC was 0.9 and 1.0 for α-SMA and NFP, respectively. Conclusion The densities of blood vessels and nerve bundles are significantly higher in the temporo-mesial dura than in the temporo-lateral dura. Although the functional relevance remains unknown, these findings provide an anatomical basis for future studies investigating nociceptive innervation and the role of neurovascular structures in post-craniotomy headache.

BackgroundSomatic pathogenic variants in EGFR have recently been implicated in lesional focal epilepsy, typically in association with low-grade epilepsy-associated tumors. Germline EGFR variants, however, have not previously been linked to epilepsy-related neuroimaging phenotypes.Case presentationWe report a large multigenerational family in which multiple individuals presented with epilepsy, progressive cognitive impairment, and striking, bilateral mesiotemporal and thalamic MRI abnormalities. Through deep phenotyping and reanalysis of exome sequencing data a rare, heterozygous, germline EGFR variant [NM_005228.5:c.866C > A p.(Ala289Asp)] was identified and shown to segregate with the neurological phenotype.ConclusionThis case report expands the phenotypic spectrum associated with EGFR by demonstrating that a germline variant can underlie epilepsy and characteristic non-neoplastic MRI abnormalities. Our findings underscore the importance of multidisciplinary re-evaluation of variants of uncertain significance (VUS) and segregation analysis in large families.

Through its global and extensive connections with multiple brain structures, the thalamus can play an important role in seizure propagation. This study investigated volumetric and functional connectivity alterations of the thalamus and more specifically the thalamic nuclei subgroups using 7T MRI in patients with MRI-negative drug-resistant focal epilepsy (DRE). Twenty-nine patients with MRI-negative DRE and 49 healthy controls underwent 7T MRI, including T1-weighted and resting-state functional MRI sequences. Thalamic nuclei segmentations were derived using automated segmentation tools and split into anterior (ANT), medial, ventral, and posterior nuclei groups. Functional connectivity with the rest of the brain was assessed using degree centrality (DC). Linear regression models evaluated group differences and relationships with epilepsy characteristics while controlling for age and sex. Asymmetry indices assessed the ipsi- vs. contralateral differences in the patient cohort. Patients showed decreased bilateral medial and increased bilateral ventral relative volumes, alongside a right-sided ANT volume increase, compared with controls. DC was increased in the left posterior and ventral nuclei. Both volume and DC in the medial, ventral, and whole-thalamic ROIs were related to epilepsy duration, while ventral and whole-thalamic DC asymmetry distinguished patients by seizure type and seizure duration. Both structural and functional alterations of the thalamic nuclei groups in patients with DRE were observed. Ventral, medial, and posterior nuclei metrics show promise as imaging biomarkers of disease burden and seizure severity, thus encouraging further research into both structural and functional properties of thalamic nuclei in focal epilepsy.

BACKGROUND:In temporal lobe epilepsy (TLE), locally reduced glucose metabolism (i.e., hypometabolism) is indicative of the epileptogenic onset zone (EZ). Here, we investigate the potential value of resting-state fMRI (rs-fMRI) for localizing the EZ with fluorodeoxyglucose positron emission tomography (FDG-PET) as ground truth. METHODS:Twelve PET-positive patients (34.1 ± 13.1 y; 5 females) with unilateral drug-resistant TLE were included. FDG-PET and rs-fMRI were acquired simultaneously at a hybrid 3T PET-MR scanner. Hypometabolic regions were identified on the FDG-PET images by a nuclear medicine expert. The FDG-PET images were compared with a clinical FDG-PET control dataset with normal glucose uptake distribution. The output z-score maps were thresholded at z < -2 to produce a binary mask of the significantly hypometabolic regions. The hypometabolism masks were mirrored onto the contralateral hemisphere for the asymmetry comparison. Regional homogeneity (ReHo), amplitude of low-frequency fluctuations (ALFF), and fractional ALFF (fALFF) were calculated from the rs-fMRI in conventional (0.01-0.1 Hz) and slow-3 (0.073-0.198 Hz) frequency bands. Asymmetry indices (AIs) were calculated using the ipsilateral and contralateral hypometabolic masks in the PET-positive subjects and assessed via the one-sample Wilcoxon test and Spearman correlation coefficients. RESULTS:The AIs of conventional fALFF were significantly lower in the hypometabolic zone (p < 0.05). A significant negative correlation was found between the AIs of FDG-PET and fALFF in the slow-3 band (r = -0.62; p < 0.05). CONCLUSIONS:Conventional and slow-3 band fALFF showed a potential to mimic the FDG-PET findings in terms of EZ localization. Further research with extended cohorts and histopathological validation is required to determine the clinical value.

PURPOSE:Deep learning (DL) techniques may support localizing the epileptogenic zone (EZ) and improve surgical outcomes in drug-resistant epilepsy. This systematic review synthesizes current evidence on DL-assisted EZ localization from neuroimaging acquisitions, aiming to outline methodological trends, limitations, and future directions that bridge the gap between clinical translation and technological advances. METHODS:We systematically searched PubMed, Scopus, and Embase (via Ovid) on April 15, 2025, for studies applying DL to localize the EZ using neuroimaging data. The bias and applicability of studies was assessed using the PROBAST+AI tool. We extracted methodological details, as well as key performance metrics. RESULTS:Thirty-six studies met the eligibility criteria, most focusing on segmenting epileptogenic lesions using structural MRI. Focal cortical dysplasia was the most commonly targeted pathology, with fully convolutional networks being the predominant DL architecture. Approximately two-thirds of the studies showed high risk of bias and clinical applicability concerns, limited by non-representative cohorts and suboptimal evaluation methods. Five studies reported promising EZ detection rate in MRI-negative cases using large multi-center cohorts, yet progress in fine-grained localization tasks, such as lesion segmentation, remained moderate. CONCLUSION:This review highlights methodological limitations hindering the clinical translation of current DL approaches for EZ localization and provides a comprehensive set of recommendations to address them. Future work should prioritize developing standardized, clinically informative evaluation frameworks and explore research avenues aligned with modern DL practices, spanning from uncertainty quantification to large-scale vision foundation models and synthetic data generation.

Microvascular remodeling is implicated in the pathophysiology of drug-resistant temporal lobe epilepsy (TLE). However, characterizing these changes in adult human surgical tissue is methodologically limited by the accumulation of lipofuscin, an autofluorescent pigment that obscures microvascular structures and confounds standard automated quantification. To address this, we developed a dual-modality workflow optimized for archival human tissue obtained from drug-resistant TLE patients and one post-mortem control. This approach integrates hematoxylin and eosin (H&E) staining for precise anatomical subfield delineation with lectin-based fluorescence imaging and spectral unmixing, a computational technique that separates specific vascular signals from overlapping lipofuscin autofluorescence. Using QuPath, an open-source image analysis platform, we validated the accuracy of this automated workflow by comparing the microvascular area fraction (MAF) against manual ground-truth annotations in randomized regions of interest. The automated workflow demonstrated excellent concordance with manual assessment (Spearman's ρ = 0.997, p < 0.001). Application of this method to a cohort of TLE patients revealed substantial inter-patient heterogeneity. Exploratory analysis indicated a positive correlation (ρ = 0.68) between hippocampal MAF and preoperative seizure frequency, suggesting a potential link between higher seizure burden and increased microvascular density. Furthermore, the workflow successfully resolved subfield-specific vascular heterogeneity within sclerotic tissue that is typically obscured by whole-region average morphometry. This study establishes a robust, spectrally-unmixed morphometry pipeline that effectively resolves lipofuscin artifacts in adult human brain tissue, providing a necessary methodological foundation for future pathology-stratified investigations into cerebrovascular remodeling in epilepsy.

Objective Stereoelectroencephalography (sEEG) is commonly employed in the workup for epilepsy surgery in patients with focal drug-resistant epilepsy (DRE). Intracranial hemorrhage is a known complication, with reported incidence rates ranging from .9% to 19.1%. Rarely, pseudoaneurysms have been reported in literature as a potential cause. This retrospective cohort study aims to describe the occurrence, clinical characteristics, and management of iatrogenic pseudoaneurysms following sEEG and the clinical outcome of the described cases.Methods A cohort of 395 patients (4067 depth electrodes) with DRE who underwent sEEG was retrospectively analyzed. The identified patients with pseudoaneurysms were analyzed in detail, focusing on timing of detection and location of the aneurysms, clinical characteristics, management strategies, and clinical outcome.Results A symptomatic iatrogenic pseudoaneurysm was identified in six of 395 cases (1.5%), with a per-electrode risk of .15% (6/4067); all occurred at the M2/M3 branches of the middle cerebral artery. All six cases presented with intracerebral or subarachnoid hemorrhage. Aneurysms were detected with combined cerebral computed tomographic angiography (CTA) and digital subtraction angiography (DSA) and treated without complications by surgical clipping or endovascular embolization. The depth electrode implantation and planned sEEG recording had to be either prematurely discontinued or canceled in four of six cases. No patients died; five experienced neurological symptoms and required prolonged hospitalization, with four needing additional rehabilitation.Significance Pseudoaneurysms following sEEG represent a serious complication with significant clinical consequences and warrant early detection and intervention. Occurrence is underreported in literature. It is recommended to use CTA and DSA when a pseudoaneurysm is suspected, particularly in cases of intraparenchymal or subarachnoid hemorrhage, and especially when depth electrodes are in close proximity to a blood vessel.

As the main inhibitory neurotransmission system, the GABAergic system poses an interesting yet underutilized target for molecular brain imaging. While PET imaging of postsynaptic GABAergic neurons has been accomplished using radiolabeled benzodiazepines targeting the GABAA receptor, the development of presynaptic radioligands targeting GABA transporter 1 (GAT1) has been unsuccessful thus far. Therefore, we developed a novel GAT1-addressing radioligand and investigated its applicability as a PET tracer in rodents. We selected a lipophilic nipecotic acid scaffold that is known to bind selectively to GAT1 as the basis for our radioligand. To obtain the desired candidate radiotracer [ 18 F]4, ester-protected radioligands [ 18 F]11a-b were synthesized through aliphatic nucleophilic radiofluorination of the respective bromo-precursors, after which chemical deprotection was attempted using various conditions. Because these deprotections were unsuccessful, it was evaluated whether the ethyl ester [ 18 F]11a could function as a prodrug and afford the active radioligand [ 18 F]4 after in vivo ester hydrolysis by esterases. Unfortunately, PET imaging studies in a rat model using [ 18 F]11a showed no brain uptake of the radiotracer. Instead, significant uptake of radioactivity was observed in the liver and bones, the latter being caused by radiodefluorination of the PET tracer. Since the PET tracer developed in this study was found to be unstable, further efforts should investigate the development of a more stable GAT1-addressing PET tracer without the potential labile benzyl fluoride moiety. Moreover, as the still intact fraction of the radiotracer did not cross the BBB, options other than the prodrug approach should be considered to increase the BBB permeability of future GAT1 radioligands.

Magnetic resonance imaging (MRI) is the preferred diagnostic tool for the detection of structural cerebral lesions in patients with epilepsy. Ultra-high field (UHF) MRI with field strengths ≥7 Tesla has been reported to improve the visualization and delineation of epileptogenic lesions. The use of ex vivo UHF MRI may expand our knowledge on the detection and detailed micromorphology of subtle epileptogenic lesions by bridging the gap between in vivo MRI and histopathology. A systematic review of available literature was conducted following PRISMA guidelines. A descriptive analysis of included articles was performed, focusing on (I) the ability of ex vivo UHF MRI to detect subtle abnormalities related to epilepsy, (II) different post-processing methods, and (III) concordance between UHF MRI and histopathology. Eleven studies with focus on the depiction of focal cortical dysplasia (n = 4) or hippocampal sclerosis (n = 7) as causative lesion of drug-resistant epilepsy were included. Ex vivo UHF MRI proved its ability to visualize the anatomy of cortical and hippocampal structures in greater detail when compared to ex vivo conventional field strengths. Different MRI post-processing methods enabled differentiation between lesional subtypes and provided novel insights into (peri)lesional characteristics. Concordance between ex vivo UHF MRI findings and histopathology was high. Acquisition of ex vivo UHF MRI and its image processing has the potential to depict epileptogenic abnormalities in greater detail with a spatial resolution approximating histological images. The translation of ex vivo UHF MRI features to in vivo clinical settings remains challenging and urges further exploration.

In resective epilepsy surgery for drug-resistant focal epilepsy (DRE), good seizure outcome is strongly associated with visualization of an epileptogenic lesion on MRI. Standard clinical MRI (≤ 3 Tesla (T)) may fail to detect subtle lesions. 7T MRI enhances detection and delineation, the potential benefits of increasing field strength to 9.4T are explored. A 36 years old male patient with DRE evaluated for resective surgery, in which 3T and 7T MRI failed to detect any epileptogenic lesions, was submitted to a dedicated epilepsy scan protocol using T1 and T2* weighted imaging at 9.4T. Images were evaluated independently by two neuroradiologists and one neurosurgeon. 9.4T MRI offered increased spatial resolution and enhanced depiction of anatomical structures vital for epilepsy imaging, exemplified by regions mesio-temporal (hippocampus, amygdala), latero-temporal, insula, frontal and temporal operculum, and gray-white matter junction (precentral gyrus/frontal lobe) compared to 3T and 7T, albeit with challenges in mesial-temporal and antero-inferior temporal lobe imaging. No epileptogenic lesion was identified. 9.4T demonstrates promise in the identification and delineation of anatomical structures and small epileptogenic lesions in patients with DRE eligible for resective surgery. Whether clinical 9.4T MRI in DRE has clinical advantages over 7T or leads to a more complete resection of the epileptogenic zone and improved seizure outcome after epilepsy surgery needs to be established.

This case study demonstrates the value of combined 7 T structural and functional MRI in the presurgical workup of a 24-year-old male with drug-resistant focal epilepsy who was initially considered MRI-negative on clinical 3 T MRI. The patient underwent extensive presurgical workup with 7 T MRI, magnetoencephalography, stereo-electroencephalography, and resection of the suspected right frontal epileptogenic zone. Histopathology showed focal cortical dysplasia (FCD) type IIb. The patient remained 11 months after surgery seizure-free. Retrospective analysis revealed that both structural and functional 7 T MRI showed abnormalities within the resected area. Morphometric Analysis Program (MAP18) detected abnormalities on both 3 T and 7 T images. However, abnormalities were more conspicuous on 7 T. Resting-state functional MRI metrics, particularly regional homogeneity and fractional amplitude of low-frequency fluctuations, demonstrated significantly increased values in both a MAP18-defined region of interest and the entire resected area compared to a healthy control group (p < 0.05). However, extensive unspecific abnormalities were also observed outside the resected region, highlighting the importance of a multimodal approach. This case study illustrates that advanced image processing of ultra-high field structural and resting-state functional MRI scans may enhance the detection of subtle epileptogenic lesions in presurgical evaluation, potentially improving post-operative seizure outcome and associated quality of life.

OBJECTIVE:To investigate whether local lesions created by stereo-electroencephalography (SEEG)-guided radiofrequency thermocoagulation (RFTC) affect distant brain connectivity and excitability in patients with focal, drug-resistant epilepsy (DRE). METHODS:Ten patients with focal DRE underwent SEEG implantation and subsequently 1 Hz bipolar repetitive electrical stimulation (RES) for 30 s before and after RFTC. Root mean square (RMS) of cortico-cortical evoked potentials (CCEPs) was calculated for 15 ms to 300 ms post-stimulation with baseline correction. Contact pairs were categorized as both coagulated, hybrid, or both non-coagulated. The data were divided into nine categories based on the stimulating and recording contact pair combinations. RMS of CCEPs was compared before and after (<12 h) RFTC using a two-sample t test (Hochberg corrected, p < 0.05) for each patient. Boost score, indicating power increase during seizures before RFTC relative to baseline, was analyzed in 4 s windows with 1 s overlap during seizure duration. RESULTS:RFTC altered connectivity across all categories. Of interest, decreases and increases in RMS were observed in connections between non-coagulated contacts distant from coagulation site (range: 1.09-85 mm, median = 17.7 mm, interquartile range [IQR] 10.1-32.3). Contact pairs involved in significantly altered non-coagulated connections showed a higher boost score correlation in the theta, beta, and gamma bands, as well as a stronger maximum correlation with coagulated sites in the delta band than contacts for which connectivity did not change after RFTC. SIGNIFICANCE:This study highlights how local lesions alter distant brain connectivity, providing insights for future research on epilepsy network changes and seizure outcomes following RFTC.

BackgroundIn contrast to clinical effectiveness of resective epilepsy surgery (RES) for patients with drug-resistant epilepsy, societal costs of RES is still unclear. The aim of this study was to report on total societal costs up until two years after surgery and analyse the trend of post-surgical costs over time. Secondary objectives included assessing quality of life (QoL) changes and identifying determinants of post-surgical costs.MethodsData were derived from the patients' entire medical history based on hospital files and accompanied by validated questionnaires before and 3-, 6-, 12-, and 24-months post-surgery to additionally include medical consumption outside of the hospital, productivity losses and gains, and QoL. To explore the trend of post-surgical costs over time and identify determinants of post-surgical costs, linear mixed effects and linear regression models were performed.ResultsThe study included 44 patients. Mean complete costs from diagnostics and treatment strategies in the period before referral for pre-surgical evaluation up until two years after RES were 121,856 (Interquartile range = 76,058-137,027). Post-surgical costs significantly decreased 12 months (mean 3-month difference = -6,675, p = 0.000) and 24 months (mean 3-month difference = -7,690, p = 0.000) after surgery compared to 3 months before surgery. Higher post-surgical costs were associated with a clinically relevant increase in disease-specific QoL after RES (p = 0.000), previous ketogenic diet (p = 0.005), RES in the left hemisphere (p = 0.014), previous RES (p = 0.007), and higher diagnostics and treatment strategies costs before referral for pre-surgical evaluation (p = 0.021). For disease-specific and generic QoL, 20 (45%) patients reached a clinically relevant QoL increase two years after surgery compared to before RES.ConclusionIn conclusion, RES leads to significant reduction in costs 2 years post-surgery. History of RES and ketogenic diet, clinically relevant disease-specific QoL increase, surgery in the left hemisphere, and higher costs of diagnostics and treatment strategies before referral for pre-surgical evaluation were significant determinants for higher post-surgical costs after RES.

OBJECTIVE:Resective epilepsy surgery is an evidence-based treatment option for patients with focal drug-resistant epilepsy (DRE). Seizure outcome after surgery is largely dependent on detection and delineation of an epileptogenic lesion on magnetic resonance imaging (MRI). However, detection fails in 30% of patients at 3 Tesla (T) MRI, thereby limiting surgical options. Diagnostic and therapeutic gain of ultra-high-field MRI in patients with 3T MRI-negative DRE is evaluated in the EpiUltraStudy. Here we report the diagnostic gain of structural 7T MRI. METHODS:Inclusion criteria were age ≥12 years and DRE with a suspected epileptogenic focus and negative conventional 3T MRI during pre-surgical workup. Images were evaluated independently by two neuroradiologists and a neurologist or neurosurgeon in two runs: blinded (Run 1) and with the results of additional clinical investigations (Run 2). RESULTS:Sixty patients underwent 7T MRI. No persistent adverse events were reported. Visual assessment of 7T MRI identified lesions in 9 cases (15%), undetected on prior 3T MRI. Possible positive scan rates increased from 17% (10/60) in the blinded run to 47% (28/60) in the informed run. However, after consensus review, many of these were reclassified as negative. Eight of nine positive 7T MRI scans were initially identified by only one or two assessors. After reassessment, a total of 56% (5/9) of 7T lesions were retrospectively identified on 3T. SIGNIFICANCE:Our data suggest a benefit of 7T MRI for the detection of subtle epileptogenic lesions in patients with DRE and negative 3T MRI. Although the detection rate may appear modest compared to other reports, we present a nuanced discussion of our methodology and patient population, contributing meaningful context to the current literature. The availability of multimodal information and consensus reviews enhanced diagnostic accuracy but with higher rates of false positives, underscoring the importance of multidisciplinary cooperation in the clinical care for patients with DRE. TRIAL REGISTRATION NUMBER:www.trialregister.nl: NTR7536.

Background Living with epilepsy, especially drug-resistant epilepsy (DRE), imposes several challenges for people diagnosed with the condition. These challenges include the physical and mental implications of epilepsy on both caregivers and patients with epilepsy. For the more than 120 000 individuals living with this neurological disorder in the Netherlands, along with their families, daily activities become hazardous, limited and costly, significantly affecting their health-related quality of life (HRQoL). As data on the burden of epilepsy in the Netherlands are lacking, studies attempting to capture the impact of epilepsy on individuals, caregivers and society are needed to enhance understanding and help address the burden of epileptic seizures.Methods and analysis The study is part of the AIM@EPILEPSY project. The project aims to develop a planning suite enabling cost-saving, minimally invasive treatment for epilepsy. By surveying 330 people with epilepsy and an anticipated sample of 150–200 informal caregivers across the Netherlands, using standardised questionnaires focusing on associated societal costs and the impact on HRQoL, this bottom-up, prevalence-based prospective study aims to understand the societal burden of DRE in the Netherlands. The data will be collected at 0, 3, 6 and 12 months of follow-up. The study results will describe the economic impact of epilepsy, focusing on cost-of-illness (€) and HRQoL (utilities) in the Netherlands.Ethics and dissemination The proposed study was approved by the Maastricht University Medical Ethics Review Committee (Approval reference: FHML-REC/2024/067/Amendment/2024_16). The result of the study is planned to be published in a peer-reviewed journal and presented at international and local scientific conferences.

OBJECTIVE:In temporal lobe epilepsy (TLE), detection of the epileptogenic zone predicts a good surgical outcome. When submitted to 18F-fluorodeoxyglucose positron emission tomography (PET), some patients display lateralized, focal hypometabolism in the temporal lobe (PET+), whereas others appear normometabolic (PET-). However, the mechanism behind this metabolic difference remains unclear. This study aimed to identify differential molecular mechanisms in these patient subtypes. METHODS:Neocortical and hippocampal biopsies of TLE patients (n = 3 PET+, n = 3 PET-) and nonepileptic postmortem controls (n = 3) were analyzed for lipid distribution using mass spectrometry imaging (MSI). Laser capture microdissection of the neocortical gray matter and hippocampal cornu ammonis and dentate gyrus was guided by MSI-derived lipid profiles and histological annotations. Dissected areas were then subjected to liquid chromatography- tandem mass spectrometry-based label-free quantitative proteomic analysis. RESULTS:MSI showed distinct lipid profiles, namely, phosphatidylserines were more abundant in PET+ samples in both the neocortex and hippocampus. Proteomic analysis showed significant differences between TLE and nonepileptic postmortem controls involving pathways in neuron excitability and neurotransmitter transporters, which were upregulated in TLE. Compared to PET-, all PET+ specimens displayed significantly dysregulated calcium signaling. Additionally, the neocortex of PET+ patients showed a shift from mitochondrial to cytosolic (cytoplasm of the cell) processes, whereas the hippocampus was characterized by a disruption of glycosylation and polyamine metabolism. SIGNIFICANCE:The applied spatial omics approach demonstrated localized molecular differences between metabolic subtypes of TLE patients. These findings may further specify these TLE subtypes and provide leads for targeted treatment.