Intracerebral hemorrhage (ICH), a hemorrhagic stroke subtype, is associated with high mortality and severe disability. Conventional craniotomy has long been the standard surgical approach; however, its invasiveness often results in postoperative complications and prolonged recovery time. Neuroendoscopic hematoma evacuation has emerged as a minimally invasive alternative that offers reduced blood loss, shorter operative time, and improved neurological outcomes if appropriately applied. Recent meta-analyses and international guidelines supports its role in lowering mortality, shortening hospital stay, and decreasing infection rates compared to craniotomy. Careful preoperative evaluation, including patient background, anticoagulant or antiplatelet status, and vascular imaging, is essential to determine suitability and exclude vascular malformations or tumor-related hemorrhages. Surgical strategies must balance endoscopic and open approaches according to the hematoma location, volume, consistency, and associated pathology. Superficial, large, or firm hematomas often require small craniotomies and two-hand techniques, whereas deeper or ventricular lesions require burr hole surgery. Additionally, instrument selection and operative maneuvers are critical for safe and effective evacuation. Neuroendoscopic hematoma removal, if performed properly, represents a promising standard of care for ICH, combining minimal invasiveness with favorable clinical outcomes.

BACKGROUND:Endoscopic transnasal surgery (ETS) has become an established treatment for skull base lesions; however, its lateral reach to the pterygopalatine fossa (PPF) and infratemporal fossa (ITF) remains limited due to restricted maneuverability within the nasal corridor. To address this limitation, the endoscopic modified medial maxillectomy (EMMM) and the direct approach to the anterior and lateral part of the maxillary sinus (DALMA) provides lateral access through the maxillary sinus. This study evaluated the technical feasibility and outcomes of ETS combining EMMM and DALMA. METHOD:A retrospective review was conducted on five patients (January 2021-April 2024) who underwent ETS involving EMMM and/or DALMA. Surgical trajectory, extent of resection, and postoperative outcomes were analyzed. EMMM preserved nasolacrimal duct and opened the medial maxillary wall for direct access to the PPF and ITF. In DALMA, submucosal dissection was extended laterally beyond the piriform aperture to remove the anterior maxillary wall creating as an additional port complementary to EMMM. RESULTS:Two patients (trigeminal schwannoma, idiopathic cerebrospinal fluid leak) underwent EMMM alone, and three patients (meningiomas extending to the ITF/PPF) underwent combined EMMM and DALMA. The dual-portal configuration provided separate working corridors for the endoscope and instruments. This arrangement minimized mutual interference and improved surgical maneuverability, allowing exposure of the lateral skull base up to the medial border of the mandible. Gross or subtotal resection was achieved in all cases. Postoperative complications were minimal; one patient experienced slight worsening of facial numbness, and one experienced slight numbness in the upper lip, likely due to DALMA-induced injury of the anterior superior alveolar nerve. CONCLUSIONS:Combining EMMM and DALMA approaches provides a safe and minimally invasive option for treating lesions extending laterally into the ITF and PPF. Dual-portal configuration appears to improve instrument maneuverability and facilitate more extensive resection, thereby potentially expanding the applicability of ETS.

This video demonstrates endoscopic transnasal "microsurgery" for a suprasellar meningioma involving the anterior communicating artery complex. A 44-year-old woman presented with visual loss due to a suprasellar tumor. Preoperative three-dimensional simulation aided in planning the expanded skull base exposure. Using bimanual dissection and meticulous vascular handling, the tumor was resected while preserving critical structures. Skull base reconstruction employed multilayered techniques with dural suturing. This case illustrates how endoscopic microsurgical strategies enable safe resection of anatomically challenging tumors, combining the benefits of endoscopic visualization and microsurgical precision for optimal outcomes. The video can be found here: https://stream.cadmore.media/r10.3171/2025.10.FOCVID25131.

BACKGROUND:Intracranial catheter navigation relies on haptic cues interpreted as resistance. However, resistance perception is subjective, limiting standardized training. Prior studies measured forces at the proximal device end, but vessel-wall deformation during catheter advancement has not been synchronized with expert resistance judgment. In this feasibility study, outer-wall strain was used as a relative index of wall deformation in a tortuous vascular phantom. METHODS:Six board-certified neurointerventionalists, each performing one navigation trial, advanced a 0.021 inch microcatheter over a 0.014 inch microguidewire through a tortuous vascular phantom with nine sequential bends, eight instrumented with outer-wall strain gauges. Operators reported mild resistance and unacceptable resistance, defined as resistance beyond which advancement was judged unsafe in this phantom. Vessel strain was recorded continuously without real-time feedback. RESULTS:In this phantom, when mild resistance was first reported, maximum strain among instrumented gauges reached 410.8±102.9 µε, localized approximately two bends proximal to the catheter tip, on average. At unacceptable resistance, maximum strain increased to 850.3±219.8 µε at the most proximal gauge. Peak strain location shifted proximally as perceived resistance escalated, and further distal tip advancement ceased. Strain at unacceptable resistance consistently exceeded that at mild resistance. CONCLUSIONS:In this phantom, expert resistance perception was associated with reproducible vessel-wall strain patterns. Because microstrain values are model-specific, they should be viewed as relative deformation indices, not patient-applicable thresholds or measures of in vivo wall stress. Linking subjective resistance to quantifiable wall deformation may support objective assessment of resistance perception and proficiency-based simulation training, pending validation.

Anterior skull base meningiomas often cause visual decline by compressing the optic apparatus. The authors present a tuberculum sellae meningioma with optic canal involvement treated via an endoscopic endonasal approach (EEA). Early devascularization, stepwise detachment, and sharp dissection preserved surrounding neurovascular structures and perforating arteries. Optic canal drilling enabled complete removal, and multilayer reconstruction ensured watertight closure. Gross-total resection was achieved without complications. Visual acuity improved from 0.7 to 1.2, with resolution of visual field defect. This case highlights the EEA as a standard technique for optimal visual outcomes in anterior skull base meningiomas with optic canal involvement. The video can be found here: https://stream.cadmore.media/r10.3171/2025.10.FOCVID25176.

Skull base chordomas and chondrosarcomas are rare bone tumors predominantly found in the petroclival areas and involve the cranial nerves, internal carotid arteries, and brain stem. Their clinical aggressiveness and high risk of recurrence necessitate multimodal treatments, including extensive surgical resection and high-dose radiotherapy. Surgery is commonly the first step in their treatment, and ABCD rules should be respected; anatomical preservation of the innocent nasal anatomy for potential repeated surgeries in case of recurrence, block-by-block resection, coverage of the intradural residual tumor to prevent surgical site dissemination and cerebrospinal fluid dissemination, and drilling of the marginal bone. Here, we present our surgical strategy for skull base chordomas and chondrosarcomas for radical surgical resection and extirpation of the tumor.

Common carotid artery occlusion (CCAO) is a rare condition without standardized treatment, particularly in cases with long, calcified occlusions. We present a 56-year-old man with symptomatic left CCAO (Riles type 1A) treated with a hybrid surgical–endovascular approach due to limited bypass options. Although a guidewire crossed the lesion, device advancement was prevented by dense plaque. Through cervical exposure, the distal wire was grasped and traction applied, allowing balloon angioplasty and stent placement. Complete revascularization was achieved without complications. This case highlights the effectiveness of hybrid strategies for managing complex CCAO with challenging anatomical features.

Meningiomas are the most common primary brain tumors in adults and have the potential for recurrence. Although most recurrent meningiomas retain their initial World Health Organization grade, a subset undergoes malignant transformation (MT). The molecular mechanisms underlying this transformation remain poorly understood. We aimed to characterize distinct recurrence subtypes—MT and grade 1-retained recurrence (GR)—using sequential multi-omic analyses. In this study, we reviewed meningioma patients with paired histological evaluations. Among these, 10 patients experienced MT and 25 showed GR. Patients with MT exhibited significantly higher Ki-67 proliferation indices and shorter overall survival. Comprehensive molecular profiling, including matched sequential recurrences, was performed on samples from six patients each with MT and GR meningiomas. Compared to GR tumors, MT tumors demonstrated a marked increase in tumor mutation burden and copy number alterations, with deletion of cyclin-dependent kinase inhibitor 2A emerging as a key acquired event. MT cases also showed selective upregulation of cell cycle-related genes, including Forkhead box M1, a feature absent in GR tumors. Notably, even prior to recurrence, MT tumors displayed distinct global DNA methylation patterns, particularly in regions targeted by the polycomb repressive complex 2 and H3K27me3 marks. Our findings suggest that molecular signatures evolve during MT and that certain intermediate aggressive meningiomas may progress toward malignancy. This study underscores the importance of DNA methylation and transcriptomic profiling in understanding tumor progression and recurrence. While molecular profiling holds promise for prognostication, further research is needed to identify key drivers of MT and clarify their roles in meningioma pathogenesis.

The effectiveness of palliative care for cancer patients has already been widely recognized. However, in Japan, palliative care for brain tumor patients remains in its early stages, and related information is limited. This is because the treatment culture for brain tumors in Japan is unique, with primary brain tumors being treated by neurosurgeons and metastatic brain tumors being treated by the department of the primary tumor, making it difficult to collect comprehensive information on end-of-life care for patients with malignant brain tumors. This study investigated end-of-life care for patients with malignant brain tumors from the perspective of a palliative care unit at a single hospital in Japan. This study included 606 cancer patients who were admitted to the palliative care unit at Tsurumaki Onsen Hospital between January 2020 and December 2024 and received end-of-life care. Information was extracted from medical records and imaging tests, and a retrospective analysis was conducted. Of the 606 patients, 71 (11.7%) had malignant brain tumors (primary malignant brain tumors and metastatic brain tumors), of which 16 (2.6%) were primary and 55 (9.1%) were metastatic. Among the 71 cases,21 patients (29.6%) presented with impaired consciousness, and 29 patients (40.8%) were unable to take oral intake. Additionally, 15 patients (2.4%) experienced seizures during hospitalization, and 12 of these were patients with malignant brain tumors. The incidence of metastatic brain tumors was consistent with previous reports; however, based on the incidence rate, primary brain tumors are also frequently treated. Palliative care for common symptoms such as impaired consciousness and seizures in brain tumor patients is considered an important challenge for all of physicians treat brain tumors. A Japanese palliative care unit treats more brain tumor patients than anticipated. Smoothening collaboration between neurosurgeons and palliative physicians is essential for optimizing end-of-life care.

Alkylating agent temozolomide (TMZ) is a standard chemotherapeutic agent in the current treatment of glioma. However, its clinical effects are insufficient, especially for glioblastomas (GBM) that nearly inevitably recur. The primary cytotoxic mechanism of TMZ involves the direct modification of DNA and resulting futile cycle of DNA mismatch repair that induces cell death via multiple mechanisms including apoptosis, necrosis, and autophagy as well as cellular senescence. In this study, we investigated the degree to which TMZ induces cellular senescence and whether senolytic drugs, which selectively target senescent cells, could enhance the therapeutic effect of TMZ. Using GBM cell lines and patient-derived GBM cell lines, we first investigated whether TMZ induces senescence by testing β-galactosidase activity and expression of senescence-associated secretory phenotype (SASP) factors. We screened various senolytic drugs for their abilities to enhance the anti-tumor effects of TMZ. In GBM cell lines and patient-derived GBM cell lines, TMZ treatment inhibited cell proliferation and consequently induced cellular senescence. However, apoptosis induction was hardly detectable after treatment with TMZ alone. Our subsequent screening with senolytic small molecule agents revealed that Navitoclax (ABT-263), a pan-Bcl-2 inhibitor, showed a combination effect with TMZ. Unlike TMZ alone, the combination treatment of TMZ with Navitoclax induced apoptosis. Furthermore, Bcl-xL specific inhibitors exhibited the combination efficacy with TMZ, whereas Bcl-2 specific inhibitors did not, indicating that targeting Bcl-xL mediated the senolytic effect. Our results suggest cellular senescence may represent a critical mechanism of GBM evasion of TMZ treatment. Bcl-xL inhibition enhances anti-GBM efficacy of TMZ by further driving senescent GBM cells to apoptosis.

OBJECTIVE:Stereotactic radiosurgery (SRS) offers excellent tumor control for pituitary adenoma (PA); however, treatment failure occasionally necessitates salvage surgery. Comprehensive studies on salvage surgical outcomes for recurrent PA after SRS remain scarce. This study aimed to elucidate the outcomes of salvage endonasal transsphenoidal surgery (sETS) for progressive PA failing SRS. METHODS:This retrospective, two institution-based cohort study analyzed data from patients who underwent sETS for progressive PA failing SRS. Progression-free survival (PFS), disease-specific survival (DSS), and neurological and endocrinological outcomes in the sETS group were analyzed and compared with those in the primary ETS (pETS) group after propensity score matching using the following variables: age at surgery, maximum tumor diameter, highest Knosp-Steiner classification, and tumor type. RESULTS:Thirteen sETS patients (8 males [62%], median age at surgery of 56 years) with 5 nonfunctioning (39%), 6 corticotropic (46%), and 2 other functioning (15%) PAs who received median (range) follow-up of 125 ( 23-169) months were included. None of the patients experienced new neurological deficits or death after sETS. The median (range) tumor resection rate was 90% (80%-100%). The 5-year PFS and DSS rates were 55% and 77%, respectively. All 4 patients (31%) who experienced recurrence after sETS had corticotropic tumors. In the matched cohort analysis between the sETS group with 12 patients and the pETS group with 12 patients, no significant differences were observed in surgical outcomes. PFS rates were marginally higher in the sETS group than in the pETS group (80% vs 49% at 3 years, p = 0.216, log-rank test), and DSS was similar between the two groups (p = 0.543, log-rank test). CONCLUSIONS:The authors' results indicate that ETS can be safely performed as a salvage treatment after failed SRS with low complication rates and satisfactory tumor control in treatment-resistant PA.

Background: Brain arteriovenous malformations (AVMs) can cause cerebral haemorrhage, associated morbidity, and mortality if left untreated. Therefore, prophylactic interventions are essential to manage these lesions. The purpose of this study was to describe our experience of incorporating new technologies into gamma knife radiosurgery (GKRS) for AVMs, aiming to improve its effectiveness and safety. Methods: We conducted a retrospective observational study that included 1032 patients with AVMs who underwent GKRS at our institution from 1990 to 2022. We reviewed the detailed treatment techniques and updates on GKRS, including tractography-guided identification of critical white matter fibres for eloquent AVMs, GKRS with minimal targeting embolisation for high-haemorrhage risk AVMs, and rotational angiography based GKRS for all AVMs. We evaluated the GKRS outcomes for AVM obliteration, post-GKRS haemorrhage, survival, post-GKRS signal changes, and neurological preservation. Results: We collected data from 90 patients by using the most advanced techniques. The cumulative obliteration rates were 61.0

BACKGROUND AND OBJECTIVES:Intracranial schwannomas are benign peripheral nerve sheath tumors usually identified as vestibular schwannomas (VSs). Among nonvestibular intracranial schwannomas (non-VSs), trigeminal and jugular foramen schwannomas are predominantly observed. Although the loss of NF2 function plays a significant role in sporadic VS tumorigenesis, a recent large-scale study showed the involvement of other recurrent gene mutations, in addition to the SH3PXD2A-HTRA1 gene fusion, in sporadic schwannomas. However, the genetic landscape of non-VS remains unclear. METHODS:We performed targeted panel sequencing and microsatellite analysis of 22q in 51 patients with sporadic intracranial schwannomas, including 30 patients with non-VS and 21 with VS, and explored the differences in the genetic backgrounds between non-VS and VS. RESULTS:NF2 somatic mutations were frequently identified in tumor samples (25 patients, 49%); non-VS showed a significantly lower frequency of NF2 mutations than VS (26.7% vs 80.9%, respectively; P = 1.8 × 10 -4 ). Despite no differences in the frequency of 22q loss of heterozygosity between non-VS and VS, that of NF2 alterations ( NF2 mutation or 22q loss of heterozygosity) was significantly different (56.7% vs 95.2%, respectively, P = 3.2 × 10 -3 ). The NF2 , LZTR1 , and SMARCB1 germline variants that predispose for NF2 or SMARCB1 - and LZTR1 -related schwannomatosis were not identified in blood samples; however, low allelic somatic mosaicism was suspected in one case of VS without a typical phenotype. In this article, we demonstrated that in intracranial schwannomas, the frequency of NF2 alterations varied depending on the tumor location, whereas that of other known mutations did not differ between non-VS and VS. CONCLUSION:Our results suggested the potential involvement of factors other than NF2 inactivation in tumorigenesis, especially in non-VS. However, further comprehensive molecular analyses are warranted.

We demonstrate endoscopic endonasal transsphenoidal resection of a temporal encephalocele (TEn) and repair of a cerebrospinal fistula at the lateral sphenoid sinus. A 48-year-old woman presented with sudden onset of massive serous nasal discharge with severe headache. Head magnetic resonance imaging disclosed medial temporal lobe herniated though a bony defect into the sphenoid sinus. We created a three-dimensional computer model that clearly disclosed TEn protruding between the maxillary and Vidian nerves. We discussed the surgical strategy1-4 with this three-dimensional model and determined to perform endonasal surgery. With a straight approach to the encephalocele though the maxillary sinus, the trigeminal and Vidian nerves are in the way, requiring retraction of the trigeminal nerve and potentially sacrifice of the Vidian nerve to reach the encephalocele.4 Instead, when we approach from the medial side through the sphenoid sinuses with an angled scope, we can reach the encephalocele with mild retraction of the Vidian nerve. We therefore selected the endonasal transsphenoidal approach. Using 30° and 70° endoscopes, the encephalocele was detached from the bony margin, cauterized, and resected (Video 1). The skull base defect was reconstructed with multilayered closure. The postoperative course was uneventful. Magnetic resonance imaging showed that the skull base defect was successfully repaired. TEn is a rare type of meningoencephalocele, which is occasionally associated with Sternberg's canal, a remnant of the craniopharyngeal canal.5,6 Using angled endoscopes, malleable forceps, and bipolar coagulators, we could safely access the fistula and excise the encephalocele via the endonasal transsphenoidal approach.

Aggressive skull base tumors such as chordomas and high-grade meningiomas often exhibit resistance to treatment, highlighting the need for improved management combining endoscopic transnasal surgery (ETS) with adjunctive radiation therapy (RT). However, repeated ETS and RT may lead to delayed cerebrospinal fluid (CSF) leaks, posing clinical challenges. This study aimed to assess the incidence and risk factors for delayed CSF leaks. From November 2016 to October 2023, a total of 287 patients who underwent ETS for skull base lesions were analyzed, with the median follow-up of 45 months. Delayed CSF leaks were defined as leaks occurring six months or more after the last ETS procedure. Among these patients, 69 (24

Precise tissue differentiation is vital in neurosurgery, especially during endoscopic endonasal surgery (ETS), where visual information is critical. The Yellow Enhance (YE) mode, a novel image-enhanced endoscopy technology, emphasizes yellow pigments to potentially improve tissue differentiation. This study retrospectively evaluated the efficacy of YE mode in five cases (two primary pituitary neuroendocrine tumors, one recurrent skull base-invasive pituitary neuroendocrine tumor, one pituitary apoplexy, and one recurrent craniopharyngioma) using the Olympus VISERA ELITE III endoscope. Eight experienced neurosurgeons reviewed surgical videos and provided 40 structured evaluations. Statistical analyses (Kruskal-Wallis and Mann-Whitney U tests) compared scores among cases. Gross or near-total resection was achieved in all cases without neurological complications. YE mode improved differentiation between normal pituitary tissue and tumors in 80% of cases, but was less effective in cases like pituitary apoplexy with degenerative changes. Across 40 evaluations, 68% rated YE mode as "useful" or "somewhat useful," while 20% noted limited utility in complex cases, such as recurrent craniopharyngiomas. YE mode shows promise in enhancing visual differentiation during ETS, particularly for normal pituitary tissue, but its utility depends on tissue characteristics. Larger prospective studies are needed to validate these findings and explore broader applications in neurosurgery.

BACKGROUND:Augmented reality (AR) can support neurosurgical procedures by integrating 3-dimensional (3D) images into real-world views to help anatomical understanding. However, current systems are cumbersome and not attractive for trainees. Studies on wearable AR devices show promise but need further refinement. METHODS:This preliminary report assesses a novel augmented reality navigation system (ARnavS) using a simultaneous localization and mapping algorithm provided with the Vuforia SDK and a quick response code. The system was applied to burr-hole surgeries in 10 cases of chronic subdural hematoma to evaluate its convenience and accuracy. RESULTS:Ten patients with 11 hematomas underwent burr-hole surgeries using ARnavS. The system was effective without equipment issues, with an average registration time of 2.6 minutes. Discrepancy between planned and actual burr-hole locations was 3.5 mm. Skin incisions avoided 3D image of the superficial temporal artery, with no superficial temporal artery damage in any case. The mean surgical time was 37.1 minutes, and no severe postoperative bleeding occurred. CONCLUSIONS:Our ARnavS for burr-hole surgery in chronic subdural hematoma offers good 3D imaging with quick registration. It provided surgeons with better anatomical comprehension, helping to avoid injury to critical structures. Unlike conventional systems, ARnavS allows direct visualization of 3D graphics in the surgical field, beneficial for less-experienced neurosurgeons and medical students. While further studies are needed, the AR navigation system with simultaneous localization and mapping algorithm and quick response code showed precise intraoperative 3D imaging with sufficient accuracy after quick registration. While further studies are needed, it has demonstrated practical usefulness in clinical neurosurgical procedures.