Coil embolization remains an important technique for treating cerebral aneurysms, even with the development of new devices such as flow diverters and flow disruption systems. To achieve stable occlusion, it is important to use coils in three steps: framing, filling, and finishing. The framing coil creates the initial support inside the aneurysm and helps prevent rupture during the procedure. Filling coils are then placed to pack the aneurysm densely and evenly. Finishing coils are used at the end to close the small space near the neck and reduce the risk of recurrence. As aneurysms vary in shape-simple, irregular, or very small-the optimal coil strategy differs from case to case. Selecting the appropriate type of coil for the aneurysm shape and catheter position is essential for both safety and effectiveness. This review explains practical considerations for each step and shows how aneurysm morphology can guide coil selection to improve treatment outcomes.

Neurophysiological biomarkers are needed to characterize the condition of patients with spinal cord injury (SCI), for which effective symptomatic biomarkers are lacking. We recorded the resting-state magnetoencephalography data of 22 patients with SCI and 29 healthy controls. Power spectral density and phase-amplitude coupling (PAC) were assessed for six frequency bands using source-reconstructed cortical currents. Compared with controls, SCI patients exhibited significantly reduced gamma band power and increased beta-gamma PAC in the frontal cortex, including the primary motor area (q < 0.05, FDR corrected). No significant differences were observed in alpha or beta power. These results suggest that decreased gamma power and increased beta-gamma coupling reflect altered cortical dynamics after SCI and may serve as potential neurophysiological signatures for chronic cortical adaptation.

BACKGROUND AND OBJECTIVES:Placement of stereotactic electroencephalography (SEEG) electrodes involves insertion of an obturator toward the target under image guidance without direct vision. Thus, tactile feedback during obturator manipulation is key to avoiding complications. Resistance encountered during advancement of the obturator that hinders planned electrode placement has prompted us to investigate the factors contributing to this resistance. METHODS:We analyzed 168 trajectories in 24 consecutive patients who underwent SEEG electrode placement between May 2019 and March 2023: 135 were placed using a 1.5-mm obturator and 33 were placed using a 0.86-mm obturator. The depth at which resistance was encountered was documented intraoperatively and compared with the preplanned trajectory to determine the structure where resistance occurred. Factors that may contribute to resistance were analyzed. RESULTS:Resistance was encountered in a total of 22 trajectories: 19 from the 1.5-mm obturator group and 3 from the 0.86-mm obturator group. Sulcal bank penetration was observed in 15 trajectories (68%) with resistance and in 42/146 trajectories (29%) without resistance. Sulcal bank penetration contributed most to resistance, more than lesion presence or trajectory length. In the 1.5-mm obturator group, insertion angles differed between trajectories with and without resistance (37.1° ± 19.0 vs 58.8° ± 15.5, 95% CI = 11.8-31.6, P = .000055). The difference remained significant when considering all pia penetrations, including at the cortical surface (37.6° ± 18.5 vs 66.1° ± 13.3, 95% CI = 21.3-35.5, P = 2.19 × 10-13). CONCLUSION:Sulcal bank penetration is the main factor contributing to resistance; resistance risk increases as the insertion angle decreases. Our findings guide forecasting resistance during sulci-traversing in SEEG electrode implantation, which may be unavoidable for optimal gray matter coverage, although forceful advancement against resistance should be avoided to minimize hemorrhagic risks.

Background:Tentorial meningioma resection is among the most challenging neurosurgical procedures. Various surgical approaches must be considered, including subtemporal, lateral suboccipital, occipital interhemispheric supratentorial, and supracerebellar transtentorial (SCTT) techniques. However, performing tentorial meningioma resections in the SCTT approach using operative microscopy often requires awkward positioning for the neurosurgeon. In this study, we report two cases of tentorial meningioma resection and discuss the utility and limitations of the 4KHD 3D operating room layout, showing the use of the exoscope (ORBEYE) system for this procedure. Methods:At our institution, we use the ORBEYE system (Olympus, Tokyo, Japan) for resecting tentorial meningioma. Peri-embolization and perioperative clinical and surgical data were retrospectively analyzed. Results:Our preferred exoscope system not only enhances visualization during neurosurgical procedures but also improves surgeon ergonomics during surgery. Conclusion:Exoscopic surgery using ORBEYE may help simplify complex neurosurgical procedures, including the resection of surgically challenging lesions such as tentorial meningiomas, although limitations remain in the management of large tumors.

ECoG-based visual semantic decoding enables inference of semantic interpretation of visual perception from complex, noisy brain activity. This study examines the feasibility of visual semantic decoding using an end-to-end deep learning framework using electrocorticography (ECoG). Specifically, the decoding task is to predict visual categories from video stimuli using time-series neural inputs. A previously collected ECoG dataset from participants (n=17) with drug-resistant epilepsy is used for analysis. With fewer than 50 training samples per visual category, this study evaluates multiple deep learning approaches, artificial neural network architectures, and frequency-band filtered inputs. The best-performing approach is analyzed to shed light on the discriminative information it relies on across spectral, temporal, and cortical dimensions. The selected decoding system uses mixup augmentation, a Transformer-based encoder, and high-gamma (80-150 Hz) inputs with a 900 ms post-stimulus window. Further analysis shows that early visual cortex (V2-V4), ventral stream visual cortex, MT+ complex with neighbouring visual areas, and lateral temporal cortex contributed substantially to decoding performance. This study demonstrates that an end-to-end deep learning framework can yield promising decoding performance from dynamic visual stimuli without handcrafted features, while the model behavior remains interpretable through spectral, temporal, and cortical dimensions, which are broadly consistent with established neuroscience knowledge.

Enlarged parietal foramina (EPF) are rare, bilateral, symmetric calvarial defects, most commonly inherited in an autosomal-dominant manner. We report an exceptionally rare case of a ruptured parietal arteriovenous malformation (AVM) situated immediately beneath an EPF and resected via the calvarial defect. A 46-year-old man with no prior medical history presented with acute left upper-limb incoordination. Head computed tomography revealed a 3-cm right parietal subcortical hemorrhage and bilateral symmetric parietal defects; similar defects in his mother, uncle, and grandfather supported a diagnosis of familial EPF. The hemorrhage was directly subjacent to the defect, without antecedent trauma. Angiography identified a Spetzler-Martin grade I AVM within the hematoma. Using the EPF as a corridor, microsurgical resection was performed. The osseous defect was filled with fibrous connective tissue, and the dura was focally thickened with firm dural-arachnoid adhesions. The AVM nidus was removed en bloc. Postoperatively, left upper-limb incoordination resolved promptly and the patient was discharged with a modified Rankin Scale score of 0. Histopathology confirmed an AVM nidus and demonstrated infiltration of inflammatory cells, including polymorphonuclear leukocytes, around abnormal vascular walls and within the dura. Whole-genome sequencing revealed a pathogenic ALX4 nonsense variant (c.793C>T, p.Arg265Ter) and no pathogenic variants in established brain-AVM predisposition genes. The spatial concordance of EPF and AVM, together with the inflammatory histopathology, raises the possibility that EPF-associated inflammation may influence subjacent AVM biology or rupture susceptibility, although causality remains unproven.

Insight is a sudden transition from uncertainty to awareness of a solution, often preceded by non-conscious processing. Despite the ubiquity of insights in human cognition, the neural mechanisms underlying this pre-conscious restructuring phase remain largely unknown. Recent theoretical frameworks suggest that the hippocampus, through its capacity for rapid associative retrieval and flexible recombination of stored representations, may facilitate the non-conscious exploration that precedes insight. Hippocampal ripples associated with memory replay and consolidation, represent a promising candidate mechanism for this process. We recorded intracranial local field potentials from depth electrodes in the hippocampus of ten patients with drug-resistant epilepsy while they performed non-verbal reasoning tasks. Participants indicated the moment of solution awareness via button press, enabling precise temporal alignment of neural activity to subjective insight. We observed a significant increase in ripple rate during a pre-response window. Critically, this effect was lateralized to the right hippocampus. These findings provide the first direct human electrophysiological evidence linking right-lateralized hippocampal ripples to the non-conscious phase of insight. We propose that right hippocampal ripples support rapid retrieval and flexible recombination of representations, potentially triggering cortical processes that culminate in conscious solution awareness. ### Competing Interest Statement The authors have declared no competing interest. Japan Science and Technology Agency Moonshot R&D-MILLENNIA Program, JPMJMS2012 JST ERATO, JPMJER1801 K program, JPMJKP25Y7 Japan Agency for Medical Research and Development, JP24wm0625207 Sumino Isamu foundation

The development of algorithms to accurately decode neural information has long been a research focus in the field of neuroscience. Brain decoding typically involves training machine learning models to map neural data onto a preestablished vector representation of stimulus features. These vectors are usually derived from image- and/or text-based feature spaces. Nonetheless, the intrinsic characteristics of these vectors might fundamentally differ from those that are encoded by the brain, limiting the ability of decoders to accurately learn this mapping. To address this issue, we propose a framework, called brain-aligning of semantic vectors, that fine-tunes pretrained feature vectors to better align with the structure of neural representations of visual stimuli in the brain. We trained this model with functional magnetic resonance imaging (fMRI) and then performed zero-shot brain decoding on fMRI, magnetoencephalography (MEG), and electrocorticography (ECoG) data. fMRI-based brain-aligned vectors improved decoding performance across all three neuroimaging datasets when accuracy was determined by calculating the correlation coefficients between true and predicted vectors. Additionally, when decoding accuracy was determined via stimulus identification, this accuracy increased in specific category types; improvements varied depending on the original vector space that was used for brain-alignment, and consistent improvements were observed across all neuroimaging modalities.

Background:Sustained immune surveillance at tumor sites is considered essential for effective cancer immunotherapy; however, direct evidence of immune surveillance in humans is limited due to difficulty obtaining tumor and peritumoral tissues through invasive procedures. Methods:Peritumoral brain tissue was obtained during reoperation from a patient with diffuse astrocytoma who had received continuous Wilms' tumor gene 1 (WT1) peptide vaccination for 20 years. WT1 tetramer-positive CD8+ T cells were analyzed by flow cytometry, followed by T-cell receptor repertoire analysis and single-cell RNA sequencing. Results:A high level of T-cell infiltration was observed in peritumoral brain tissue, despite the immune-privileged nature of the central nervous system. Notably, 38.4% of CD8+  T cells were WT1-tetramer positive, exhibiting an oligoclonal pattern similar to that observed in peripheral blood. Single-cell RNA sequencing demonstrated that WT1-specific cytotoxic T lymphocytes (CTLs) were predominantly composed of resident memory T cells (Trm) and terminally differentiated effector memory T cells (TEMRA), along with a small fraction of cycling T cells. Interestingly, Trm-like subsets were also detected among WT1-specific CTLs in peripheral blood. Conclusion:These findings provide in situ evidence of long-term persistence of WT1-specific CTLs in the human brain by continuous WT1 peptide vaccination. Such local immune surveillance may have contributed to the prevention of relapse in this patient. Single-cell RNA sequencing suggests that long-lived Trm may contribute to the persistence of immune surveillance through self-renewal and generation of cytotoxic TEMRA. This study offers insights into long-term anti-tumor immunity and may inform future optimization of cancer vaccine therapy.

Background:Preoperative survival prediction in newly diagnosed glioblastoma (nGBM) remains challenging due to limited robustness and standardization across radiomic approaches. We aimed to validate a machine learning-based prognostic model using preoperative MR images and assess its generalizability. Methods:Two independent cohorts were analyzed: the Kansai Molecular Diagnosis Network for CNS Tumors (KNBTG) and The Cancer Genome Atlas (TCGA). All cases with available preoperative MR images (T1WI, T2WI, and Gd-T1WI) were included. The KNBTG cohort was divided into a training dataset (TD, n = 137) and an internal test dataset (ITD, n = 141), while the TCGA cohort served as the external test dataset (ETD, n = 105). A total of 489 texture features were extracted. Overall survival (OS) was dichotomized at the median, and predictive modeling was performed using least absolute shrinkage and selection operator regularization. The trained model was validated on ITD and ETD. Results:Radiomic high-risk status was associated with significantly shorter OS in both ITD and ETD (log-rank P < .05) and remained independently prognostic in multivariate Cox analysis. Time-dependent area under the receiver operating characteristic curves was consistently higher in models incorporating radiomic-based risk. Of the 13 selected features, "T2_core_GLCMhomogeniety_3_SD" was the only consistent predictor across cohorts and showed strong prognostic stratification, particularly between low- and high-risk groups (cutoff range: 0.0145-0.0180). Conclusions:Radiomics-based modeling provides reproducible prognostic value in nGBM. The feature "T2_core_GLCMhomogeniety_3_SD" may serve as a reliable imaging biomarker for preoperative risk stratification and individualized treatment planning.

Pain and working memory interact bidirectionally, yet most paradigms treat pain as an extraneous distractor rather than task-relevant content. This study investigated whether thermal sensations can be encoded and updated in working memory in an n-back paradigm. Nineteen healthy adults completed visual (location) and thermal (temperature) single n-back tasks, cross-modal conditions with task-irrelevant distractors, and a dual n-back task across three load levels (1-, 2-, 3-back). Results showed that thermal cues consistently yielded lower accuracy and longer response times (RTs) compared to visual cues (p < 0.001, q < 0.001). While task-irrelevant thermal input tended to prolong RTs in the visual task under low load (p = 0.033, q = 0.099), task-irrelevant visual input showed a trend-level improvement in thermal-task accuracy under high load (3-back; p = 0.020, q = 0.060), consistent with a potential cross-modal effect. Qualitative data indicated that participants strategically transcoded thermal sensations into word or numerical labels to support maintenance. These findings demonstrate that pain can be operationalized as mnemonic content, though its processing incurs significant executive costs due to transcoding demands and resource competition. By shifting focus from "pain-as-interference" to "pain-as-content", this paradigm offers a principled approach for the mechanistic study of nociceptive working memory updating and provides a foundation for quantifying cognitive interference in clinical pain populations.

Glioblastoma multiforme (GBM) is among the most malignant primary brain tumors, necessitating the development of novel therapies. Intracranial injection of chimeric antigen receptor (CAR)-T cell therapy is effective against GBM. However, whether intracranially injected CAR-T cells persist in the brain for long periods is unclear. In this study, we established a syngeneic murine model of GBM by injecting GL261 murine GBM cells expressing human B7-H3. After confirming tumor engraftment, murine T cells transduced with CAR-targeting human B7-H3 were injected intratumorally. Reduced tumor burden and enhanced survival were observed in mice injected with B7-H3 CAR-T cells compared with those injected with control T cells. CAR-T cells were distinctly detected in the brain 1 week after CAR-T cell injection, but disappeared 2 weeks after injection. In the syngeneic mouse model, intracranially injected CAR-T cells have the potential to eradicate GBM but do not persist in the brain for long, suggesting that intracranial injections of CAR-T cells need to be repeatedly administered, as has been done in several clinical trials. It will be important to develop strategies to enhance persistence of CAR-T cells in the brain.

Isolated sinus dural arteriovenous fistulas (dAVF) with cortical venous reflux are associated with a high risk of intracranial hemorrhage.1 Although transarterial embolization using Onyx is a common treatment strategy, transvenous embolization through an occluded sinus may be necessary when an appropriate arterial access route is unavailable.2-4 However, precise traversal of the occluded segment remains technically challenging. In this technical video, we demonstrate a biplane 3D roadmap technique for accurate traversal of an occluded sinus. The occluded venous sinus was segmented using contrast enhanced MRI and overlaid onto live fluoroscopic images, allowing precise guidance through the occluded segment. Previous reports have demonstrated the usefulness of 3D roadmap guidance for crossing occluded lesions; however, its application to the venous sinus has been limited.5 6 This method could provide a more reliable strategy for transvenous embolization in selected cases. The procedure is demonstrated in video 1neurintsurg;jnis-2026-025565v1/V1F1V1Video 1.