Background:We conducted a multicenter study to investigate the utility of postoperative antiseizure medication (ASM) in the occurrence of late seizure in glioblastoma. In addition, we analyzed whether postoperative ASM affects survival. Methods:1132 consecutive patients with newly diagnosed glioblastoma at 39 centers were enrolled. In patients treated with postoperative ASM (levetiracetam [LEV], lacosamide [LCM], or perampanel [PER]), as well as in those who received no medication, the cumulative incidence of late seizure, adverse events, and survival outcomes were analyzed. Results:In total, 1099 patients (female: 482, male: 617, mean age: 67.2 years) were included, among whom, 287 developed postoperative late seizure. The mean onset time of late seizure was 193.6 days after surgery. Postoperative ASMs were administered in 628 cases, LEV in 344, LCM in 124, and PER in 160. The cumulative incidence of late seizure at 12 months was as follows: no medication in 30.9%, LEV in 17.8%, LCM in 28.8%, and PER in 16.2%. Multivariable analysis disclosed that LEV and PER displayed significantly lower cumulative incidences of postoperative late seizure compared with no medication and LCM. By contrast, median progression-free survival/overall survival did not significantly differ among ASMs. However, during the 12-24 month interval, the PER group demonstrated a more favorable prognosis than the other groups. Conclusions:LEV and PER after glioblastoma surgery were associated with a reduced risk of late seizure compared with LCM or no medication. LEV or PER may be considered as postoperative ASMs to optimize seizure control and potentially help preserve patients' QOL.

Abstract Background Endoscopic endonasal skull base surgery (EESS) is widely performed for pituitary tumors. In growth hormone–secreting adenomas (GHomas), the procedure is technically more demanding than for other pituitary neuroendocrine tumor (PitNET) subtypes due to restricted instrument maneuverability. Few studies have evaluated the influence of nasal cavity morphology on this difficulty. Objective To identify anatomical factors contributing to the technical challenges of EESS for GHomas by comparing nasal cavity structures between GHoma and non‐GHoma PitNET patients. Study Design Retrospective chart review. Setting Tertiary referral center with a collaborative skull base team of neurosurgery and otolaryngology. Methods Computed tomography (CT) images of 28 GHoma and 104 non‐GHoma PitNET patients who underwent EESS between August 2018 and April 2024 were analyzed. Measurements included inter‐vidian canal distance, nasolacrimal duct opening width, inferior turbinate width, piriform aperture width, sphenopalatine foramen width, inter‐carotid artery distance, skull base–to–hard palate distance, anterior nasal spine–to–clivus distance, and anterior sphenoid wall–to–clivus distance. Comparisons were performed using Student's t ‐test. Results GHoma patients showed significantly greater nasolacrimal duct opening width, piriform aperture width, and anterior nasal spine–to–clivus distance ( P < .05). Vertical‐to‐horizontal ratios did not differ significantly. However, the inter‐carotid artery distance and the ratios of inter‐carotid distances to the anterior nasal spine–to–clivus distance were significantly smaller in GHomas. Conclusion GHoma patients possess generally larger sinonasal dimensions, yet a narrower paraclival inter‐carotid space limit surgical maneuverability. These CT‐based anatomical differences may have potential implications for preoperative anatomical assessment in patients with GHomas. Level of Evidence IV.

The cerebral blood flow (CBF) measured by multi-delay ASL (4D-ASL) offers superior diagnostic performance compared to single-delay ASL-CBF for glioma grading. Dynamic changes in signal intensity (SI) and arterial transit time (ATT) obtained from 4D-ASL may also be key factors in differentiating adult-type diffuse glioma. Furthermore, the longitudinal relaxation time (T1) of brain tumor may influence on CBF and ATT when using ASL techniques. Our purpose was to determine if time-intensity profiles from 4D-ASL using a variable-TR scheme and T1-corrected ATT (ATTT1corr) could distinguish among adult-type diffuse gliomas. The 4D-ASL with a variable-TR scheme data were collected by changing the labeling duration (LD) and post-labeling delay (PLD). Data acquisition at each phase consisted of pre-saturation and control or labeling modules followed by data acquisition. A total of 14 LD and PLD combinations were used. In addition, T1 measurement was conducted using pseudo-continuous ASL with a variable-TR scheme, without label and background suppression pulses. The SI peak time was obtained based on the time-intensity curve. The SI peak time, ATT, and ATTT1corr were compared among adult-type diffuse gliomas. Thirty patients were included in the study. ATT and the SI peak time in diffuse glioma with IDH-wildtype (IDHw) were significantly shorter than astrocytoma, IDH-mutant (p < 0.01, each). Moreover, ATTT1corr in astrocytoma, IDH-mutant was longer than the other types of diffuse glioma (p < 0.0001). The 4D-ASL with a variable-TR scheme includes ATTT1corr and the SI peak time could potentially improve the differential diagnosis of adult-type diffuse gliomas.

Background Gliomas are primary brain tumors arising from glial cells. WHO grade 2 gliomas are initially managed with surgery for diagnosis and tumor reduction. However, complete resection is difficult due to their infiltrative growth into the normal brain and the need to preserve brain function. Current treatment options for WHO grade 2 gliomas are limited. Isocitrate dehydrogenase 1 (IDH1) mutations are frequently observed in WHO grade 2 gliomas. Safusidenib erbumine is a selective inhibitor of mutant IDH1 with substantial blood-brain barrier penetration. This study aimed to investigate the efficacy and safety of safusidenib erbumine in patients with chemotherapy- and radiotherapy-naïve IDH1-mutated WHO grade 2 gliomas. Methods This phase II study implemented a multicenter, open-label, single-arm design and evaluated the efficacy and safety of safusidenib erbumine in 27 patients with chemotherapy- and radiotherapy-naïve IDH1-mutated WHO grade 2 gliomas (NCT04458272). Results The confirmed objective response rate according to the Response Assessment in Neuro-Oncology criteria for WHO grade 2 gliomas was 44.4%. Median progression-free survival was not reached, with an event-free probability of 87.9% at 24 months. The frequently reported treatment-emergent adverse events (TEAEs) by Medical Dictionary for Regulatory Activities Preferred Terms (reported in ≥40%) were alopecia (59.3%), arthralgia (55.6%), skin hyperpigmentation (48.1%), and alanine aminotransferase increased (40.7%). Treatment-emergent adverse events were characterized as mostly grade 1 or 2. The incidence of treatment-related grade ≥3 TEAEs was 18.5%. Conclusions Safusidenib erbumine is a potential treatment option for patients with chemotherapy- and radiotherapy-naïve IDH1-mutated WHO grade 2 gliomas.

BACKGROUND AND OBJECTIVES:Skull base surgery requires precise 3-dimensional (3D) anatomic understanding and advanced drilling techniques within a confined operative space. Although cadaveric dissection remains the gold standard for training, its availability is limited. This study aimed to evaluate the educational utility of a commercially available full-skull 3D model for skull base surgery training. METHODS:A full-skull 3D model reproducing the cranial base and brain was used in a hands-on training session involving 8 neurosurgeons, including 2 residents and 6 board-certified surgeons. Multiple skull base approaches were practiced. In addition, a patient-specific tumor model generated from clinical imaging data was incorporated to simulate pathological anatomy. Participants completed a questionnaire using a 5-point Likert scale to assess bone hardness, anatomic accuracy, realism, drilling sensation, safety and usability, and overall satisfaction. RESULTS:Overall satisfaction with the model was high across all evaluation categories. Anatomic accuracy, realism, and usability received high mean scores. Overlay visualization of individual responses demonstrated consistent trends without reliance on inferential statistics. Qualitative feedback indicated that the model was particularly useful for understanding spatial orientation and approach selection, whereas limitations were noted regarding tactile realism, including uniform bone hardness and dural texture. CONCLUSION:The full-skull 3D model demonstrated substantial educational value as a supplementary training tool for skull base surgery. By enabling repeated practice, approach comparison, and patient-specific simulation, this model may complement cadaver-based training, particularly for early-stage neurosurgeons. Further studies with larger cohorts are warranted to establish its role within structured skull base education programs.

Rationale and Objectives 23Na‑MR imaging requires lengthy acquisition times, it remains difficult to implement routinely in clinical workflows and limits broader clinical application. This study aimed to determine whether a TR of 60 ms (TR60) could maintain brain tumor conspicuity while reducing acquisition time compared to TR100. Materials and Methods This prospective study includes adult patients with histopathologically confirmed supratentorial brain tumors. A 3 T scanner with a dual-tuned 1H/23Na birdcage head coil was used. A 3D radial stack-of-stars sequence was employed for the acquisition of 23Na-MR images. The lesion conspicuity on 23Na-MR images was evaluated using the contrast-to-noise ratio (CNR) and CNR efficiency (CNR/√ acquisition time; time-CNR), calculated by comparing the signal intensity of the tumor with that of the background. The CNR and time-CNR were then compared between TR60 and TR100 in detecting brain tumors. Results A total of 30 patients (22 men) were enrolled. No significant differences were observed in the CNR between TR60 and TR100 (p = 0.56). The time-CNR of TR60 was significantly higher than that of TR100 (p < 0.001). Conclusion 23Na-MR imaging using TR60 achieved a significantly higher time-CNR than TR100 while maintaining comparable CNR, indicating improved acquisition efficiency for brain tumor evaluation.

To leverage a combination of cortical high-flow sign on arterial spin labeling (ASL) and cystathionine measurement using 1H-MR spectroscopy (1H-MRS) to distinguish oligodendroglioma, IDH-mutant and 1p/19q-codeleted (O_IDHm-codel) from astrocytoma, IDH-mutant (A_IDHm-noncodel). We implemented pseudo-continuous ASL technique (post-labeling delay = 2000 ms) using a 3.0-T MRI scanner. Relative perfusion maps were generated by subtracting paired labeled images from control images. 1H-MRS data were acquired by using the single-voxel point-resolved spectroscopy sequence (PRESS) sequence (TR = 2000 ms, TE = 97 ms, NEX = 128, volume of interest = 203 mm3). Our study included cases with a Cramér-Rao Lower Bound of cystathionine levels at 2.7 ppm that were below 50

Medulloblastoma (MB) is a biologically and clinically heterogeneous pediatric brain tumor. However, large-scale molecular subgrouping studies have mainly been conducted in Western populations, and comprehensive data from Asia are limited. To address this gap, we analyzed 242 MB cases collected from 39 institutions through the Japan Pediatric Molecular Neuro-Oncology Group, performing centralized molecular classification using NanoString-based gene expression profiling, DNA methylation arrays, and multiplex ligation-dependent probe amplification (MLPA)-based copy number profiling, supplemented by targeted sequencing. The subgroup distribution was 16.1% WNT, 24.8% SHH, 17.4% Group 3, and 41.7% Group 4. CTNNB1 mutations and monosomy 6 characterized all WNT cases, whereas MYCN amplification and TP53 mutations were independent adverse markers in SHH MB. Group 3 showed the worst survival, with MYC amplification and metastasis as poor prognostic factors. In Group 4, large cell/anaplastic histology predicted poor outcomes, whereas chromosome 11 loss was correlated with a favorable prognosis. Whole chromosomal aberration-defined favorable-risk patterns consistently indicate improved outcomes in non-WNT/non-SHH MBs. We also developed a simplified MLPA-based classifier targeting six loci on chromosomes 7, 8, and 11 (SEE-6-CNA), which enabled robust and clinically feasible prognostic stratification. Overall, our findings confirm that the molecular subgroup-specific features of Japanese MBs are largely concordant with global observations and that SEE-6-CNA provides a cost-effective tool to support individualized treatment planning, particularly in resource-limited settings.

BACKGROUND AND PURPOSE:Adult-type diffuse gliomas-astrocytoma, isocitrate dehydrogenase (IDH)-mutant; oligodendroglioma, IDH-mutant and 1p/19q-codeleted; and glioblastoma, IDH-wild-type-have distinct prognoses and treatment responses. Accurate preoperative subtype estimation is, therefore, important for clinical decision-making. Proton MR spectroscopy (1H-MRS) enables noninvasive assessment of tumor metabolism. Cystathionine, detectable at 2.72 ppm, has been proposed as a metabolic marker of oligodendroglioma, but its diagnostic performance across adult-type diffuse gliomas remains incompletely defined. This study evaluated the utility of cystathionine quantification by 1H-MRS for differentiating glioma subtypes and assessed whether combined analysis with 2-hydroxyglutarate (2HG) improves diagnostic performance. MATERIALS AND METHODS:Eighty-five patients with histologically and molecularly confirmed adult-type diffuse gliomas (25 oligodendrogliomas, 28 astrocytomas, 32 glioblastomas) underwent preoperative 3T MRI including the single-voxel point-resolved spectroscopy sequence for 1H-MRS (TE = 97 ms). Spectra with severe artifacts were excluded; no cases were excluded on the basis of full width at half maximum (FWHM < 12.8 Hz, 0.1 ppm at 3T). Metabolites were quantified using LCModel, with concentrations normalized to the unsuppressed water signal and relaxation-corrected. Group comparisons of cystathionine levels were performed using Kruskal-Wallis and Bonferroni-corrected pair-wise tests. The receiver operating characteristic analysis evaluated diagnostic performance for differentiating oligodendrogliomas from astrocytomas and glioblastomas. Supplementary analyses excluding spectra with cystathionine Cramér-Rao lower bounds (CRLB) ≥ 50% and combined cystathionine-2HG receiver operating characteristic were also performed. RESULTS:Cystathionine levels were highest in oligodendrogliomas (mean, 1.040 [SD, 0.908] mM), intermediate in glioblastomas, and lowest in astrocytomas (mean, 0.437 [SD, 0.403] mM). Oligodendrogliomas showed significantly higher levels than astrocytomas (P = .003), whereas no significant difference was observed between oligodendrogliomas and glioblastomas. Receiver operating characteristic analysis showed moderate diagnostic performance (area under the curve [AUC] = 0.69 for oligodendroglioma vs astrocytoma; AUC = 0.56 for oligodendroglioma vs glioblastoma). After CRLB-based exclusion, sensitivity increased but specificity decreased (AUC = 0.83 for oligodendroglioma vs astrocytoma). Combining cystathionine with 2HG modestly improved AUCs (0.72 and 0.61, respectively). CONCLUSIONS:Cystathionine quantification by 1H-MRS reflects biologically meaningful metabolic differences among adult-type diffuse gliomas, with higher levels characteristic of oligodendrogliomas compared with astrocytomas. However, overlap with glioblastomas limits its role as a stand-alone discriminator. When interpreted alongside 2HG and conventional imaging features, cystathionine may serve as a supportive metabolic marker to enhance preoperative glioma subtype classification.

IDH-wildtype astrocytomas of histological grade 2 or 3 without the WHO 2021 molecular criteria for glioblastoma—TERT promoter mutation, EGFR amplification, or combined whole-chromosome 7 gain and 10 loss (+ 7/– 10)—are designated “Not Elsewhere Classified” (NEC), a residual category with clinical behavior ranging from indolent disease to courses clinically indistinguishable from glioblastoma (GBM). However, reliable molecular markers capable of resolving this heterogeneity have not been established. We retrospectively profiled a multi-institutional cohort comprising 38 adult IDH-wildtype astrocytoma NEC cases and 429 GBM controls using a bimodal DNA/RNA next-generation sequencing panel and, in 30 NEC cases, genome-wide DNA methylation profiling. NEC tumors were markedly heterogeneous: 21 of the 30 methylation profiles (70

Although further reduction of acquisition time is needed, 3-T sodium inversion recovery MRI may enhance current diagnostic approaches for detecting isocitrate dehydrogenase–mutant astrocytoma.

Research on foundation models is actively progressing. The segment anything model (SAM) and MedSAM are representative foundation models for image segmentation. Recently, low-rank adaptation (LoRA) has been developed, allowing parameter updates without retraining the entire model, thus solving the problem with large data and time required for task-specific fine-tuning. Although many studies have used public databases, few have focused on local data. Moreover, to our knowledge, no studies have fine-tuned MedSAM using LoRA. We aimed to evaluate SAM, MedSAM, and their LoRA-tuned variants (SAM-LoRA and MedSAM-LoRA) using brain magnetic resonance images of gliomas from five centers in Japan and to compare their performance. We used 2D-based fluid-attenuated inversion recovery axial images and conducted parameter optimization based on four-fold cross-validation (189 cases) and external test evaluation (75 cases) using cases collected retrospectively. Dice coefficients, intersection over union (IoU), and the 95

The anterolateral keyhole approach has evolved as a minimally invasive strategy for lesions of the anterior skull base and surrounding circulation. In particular, the supraorbital eyebrow approach allows direct access to the frontal skull base through a small craniotomy, while preserving cosmetic outcomes and minimizing surgical morbidity. This review outlined the anatomical concepts, surgical indications, technical nuances, and limitations of the supraorbital eyebrow approach, with particular emphasis on cerebrospinal fluid drainage, instrument selection, and endoscope positioning in a narrow operative corridor. Additionally, the mini-pterional and extended-eyebrow approaches are discussed as complementary options that expand the operative field toward the lateral and Sylvian regions when required. Although minimally invasive approaches offer clear advantages, they should be selected only when surgical efficacy, including the extent of tumor resection, is equivalent to that of a standard craniotomy. Surgeons must also recognize that the management of intraoperative complications, such as bleeding, can be more challenging in a restricted field. Therefore, careful patient selection, thorough anatomical understanding, and stepwise development of experience (from simple cases to complex cases) are essential, particularly for young neurosurgeons. When applied appropriately, the anterolateral keyhole approach is a safe and effective extension of conventional cranial surgery.

BACKGROUND:En bloc subtotal temporal bone resection (STBR) is a surgical technique used for the removal of temporal bone malignancies. However, few reports detailing resection of the most medial bone in this procedure have been published, although it is the most technically challenging aspect of en bloc STBR. In this study, we focused on the anatomical details of resection of the most medial bone in en bloc STBR, and we discuss the surgical nuances involved. METHODS:Dissections were performed on 10 formalin-fixed cadaveric specimens. Following the subtemporal-infratemporal fossa and retromastoid-paracondylar approaches, resection of the medial portion to complete en bloc STBR was examined. RESULTS:To achieve en bloc STBR, we had to safely remove the bone within a triangular area anterior to the jugular fossa, posterior to the posterior genu of the petrous segment of the internal carotid artery, and directly above the carotid ridge on the medial side of the styloid process base. The region to be resected had mean (range) dimensions of 16 (12-25) mm anteriorly, 17 (12-25) mm posteriorly, and 10 (8-12) mm medially, with a total area of 76 (47-146) mm2. CONCLUSIONS:En bloc STBR is a complex and technically demanding procedure, with the medial bone being the most challenging component to resect. This study emphasizes the importance of understanding the anatomical features of the medial bone for en bloc resection. It aims to contribute to the refinement of surgical techniques for temporal bone resection.

Glioblastoma continues to have a poor prognosis, although recent advancements in multimodal treatments have gradually improved outcomes. However, treatment options have become increasingly complex and highly specialized. In rural areas, patients often travel long distances for treatments such as bevacizumab (BEV) administration, which may hinder treatment adherence and potentially lead to poorer outcomes. This study analyzed the impact of commuting distance on survival using clinical data from the Kyushu Neuro-Oncology Study Group. We measured the commuting distances of 564 patients with glioblastoma who were initially treated at 11 participating institutions between 2010 and 2023. Patients were categorized into nearby and remote groups using a threshold of 20 km, and their overall survival (OS) was analyzed using the Kaplan-Meier method. Univariate and multivariate analyses were performed using the Cox proportional hazards model, incorporating additional potential prognostic factors. In the overall cohort, there was no significant difference in OS between the nearby and remote groups (median OS: 19.2 vs. 18.3 months). However, among the 452 patients who underwent second-line treatment for recurrence, OS was significantly longer in the nearby group (median OS: 18.7 vs. 16.8 months). Univariate analysis revealed that commuting distance (P = 0.037), age, extent of resection, and performance status (PS) were all significant prognostic factors. Multivariate analysis demonstrated that commuting distance was an independent prognostic factor (P = 0.009). These results were validated through propensity score matching, which analyzed 148 patients in each group (median OS: 19.3 vs. 16.4 months). Our findings suggest that commuting distance is associated with prognosis in glioblastoma patients who require second-line treatment. To address this issue, it is necessary to establish an environment that enables the smooth and continuous delivery of multimodal treatment, particularly in rural areas.

CDKN2A/B homozygous deletion (HD) defines isocitrate dehydrogenase (IDH)-mutant astrocytomas as World Health Organization (WHO) grade 4 and predicts aggressive tumor behavior. To identify clinical and molecular prognostic factors in these tumors, we conducted a retrospective multi-institutional study of 106 adult patients diagnosed with IDH-mutant astrocytomas (21 grade 2, 40 grade 3 and 45 grade 4). Tumors were classified using a custom DNA/RNA next-generation sequencing panel based on the 2021 WHO classification. This resulted in an upgrade to grade 4 in 10.3% of cases previously classified as grade II or III due to CDKN2A/B HD. Multivariate analysis identified CDKN2A/B HD (hazard ratio [HR], 1.76; P = .005), MET fusions/splicing variants (HR, 5.38; P = .002), and PDGFRA alterations (HR, 3.66; P = .009) as independent predictors for poor overall survival. The accumulation of these 3 genetic events was strongly associated with unfavorable survival (P < .001) and correlated with adverse clinical features, including lower Karnofsky Performance Status and higher Ki-67 indices. Our study validates the prognostic value of the WHO 2021 classification for IDH-mutant astrocytomas and demonstrates that MET and PDGFRA alterations are independent adverse prognostic factors, comparable to CDKN2A/B HD. Their cumulative burden enables refined molecular risk stratification to guide clinical management.

ABSTRACT Objectives To evaluate the temporal bone paragangliomas (so‐called glomus tumors, TB‐PGLs) via the Grading System for Adrenal Pheochromocytoma and Paraganglioma (GAPP) and succinate dehydrogenase subunit B (SDHB) immunohistochemistry, and to discuss their implications for postoperative follow‐up and treatment strategies. Methods This report is a retrospective descriptive case series of histopathological findings from surgically resected TB‐PGL tissues. A retrospective analysis of 10 cases of TB‐PGL that required otologic surgical intervention at our institution between 2016 and 2025 was conducted. Tumors were classified using the Fisch and Glasscock–Jackson systems. Histopathological characteristics were assessed via GAPP scoring and SDHB immunostaining (primary outcome). The surgical approach, extent of resection, postoperative complications, and hearing preservation outcomes were also reviewed (second outcome). Results Nine of 10 tumors were classified as moderately differentiated based on the GAPP. SDHB loss was observed in larger tumors (Classes C1 and C2). Complete resection was achieved in 7/10 cases without major cranial nerve deficits. Hearing preservation surgery was performed in seven cases, whereas hearing was sacrificed in three cases owing to tympanic membrane lateralization. Conclusion Most of the TB‐PGLs were classified as moderately differentiated based on the GAPP and SDHB deficiency was observed in two cases. These findings suggest that long‐term follow‐up may be indicated for patients with TB‐PGLs. Postoperative follow‐up should incorporate pathological assessments, and adjuvant therapy may be considered in selected cases. Larger, multicenter studies with long‐term follow‐up are needed to correlate the long‐term malignant potential of TB‐PGLs to GAPP scoring. Level of Evidence 4

BACKGROUND AND OBJECTIVES:The endoscopic endonasal approach offers advantages for accessing lesions in the medial and inferior regions of the orbit; however, its feasibility and practical utility in accessing the anterior orbital region remain unclear. To evaluate the 3-dimensional feasibility and maneuverability of accessing the anterior orbit using sublabial and endonasal multicorridor approaches through anatomic study. METHODS:A total of 18 sides from 9 anatomic specimens were used for evaluation through the endoscopic endonasal ipsilateral and contralateral transethmoidal approach, endoscopic modified medial maxillectomy, and sublabial transmaxillary approach. Staged coronal cross-sections were created from the lacrimal hamulus in the anterior-to-posterior direction. The accessible ranges in the superior, inferior, and central directions from each corridor were measured and analyzed. RESULTS:The contralateral transethmoidal corridor provided significantly broader central access than the ipsilateral side, with expanded ranges of 8.9 mm (95% CI, 2.5-15.2; P = .001) and 15.6 mm (95% CI, 9.4-21.7; P < .001) at 10 and 20 mm posterior to the hamulus, respectively. Nasolacrimal duct mobilization through the endoscopic modified medial maxillectomy technique consistently expanded access in the ipsilateral transethmoidal corridor (9.6 mm at 10 mm [P < .001]; 12.7 mm at 20 mm [P < .001]), whereas its benefit in the contralateral corridor was limited to the anterior region only (11.0 mm at 10 mm [P < .001]) and was not significant at more posterior sections. The sublabial transmaxillary approach offered superior access only in the inferior direction and only in the most anterior region. CONCLUSION:Lacrimal hamulus serves as a reliable bony landmark for the anterior orbital region. The transethmoidal approach benefited significantly from nasolacrimal duct mobilization, with the greatest impact observed in the anterior orbital region on the ipsilateral side. Three-dimensional understanding of the accessibility enables the selection of the optimal surgical approach to this challenging region.

Background:Ventriculoperitoneal (VP) shunts are widely used to treat hydrocephalus in children with posterior fossa tumors. While many patients gain shunt independence after tumor control, indwelling shunts are often not removed. Shunt-related intracranial cysts are extremely rare and typically develop along the intracranial catheter tract within days to several years after shunt insertion; to date, the longest reported interval has been 19 years. Here, we report a case a cystic lesion with marked perilesional edema developing 45 years after childhood VP shunt placement for tumor-related hydrocephalus. Case Description:We report the case of a 58-year-old man who presented with acute severe left-sided hemiparesis. At the age of 13 years, he underwent resection of a posterior fossa ependymoma, VP shunt placement, and whole-brain radiotherapy. Neuroimaging revealed a large right frontal low-density lesion with vasogenic edema and a cystic cavity surrounding the intracranial shunt catheter. Retrospective review of magnetic resonance imaging performed 3 months earlier showed a smaller preexisting cyst at the same site. The shunt catheter was removed without resistance, and the membranous material adhering to the distal tip caused partial intraluminal obstruction. Postoperatively, the hemiparesis improved markedly; follow-up imaging demonstrated resolution of the edema and reduction in the cyst size. As hydrocephalus did not recur, shunt reinsertion was not required. Conclusion:This case represents the longest latency reported in the literature for VP shunt-related intracranial cyst formation, occurring 45 years after shunt implantation, exceeding the previously reported maximum interval of 19 years. The acute symptoms closely resemble stroke or infection, underscoring the diagnostic challenge. Clinicians should be vigilant of such delayed complications even decades after shunt placement.