This study aimed to develop a new, refined, and easy-to-use microvascular decompression surgical prosthesis and report its processability, uniformity, stability, and clinical safety.

In an experimental study, the processing time required to create five slings and five balls from a prototype clump (0.010 ± 0.001 grams) was measured. Similarly, the processing time to form a clump (0.01 ± 0.001 grams) by plucking an equivalent amount of fibers from commercial polytetrafluoroethylene felt was measured. After approval from the Pharmaceuticals and Medical Devices Agency, the new prosthesis was used in 39 consecutive microvascular decompression surgeries.

The handling time to make slings and balls from the refined polytetrafluoroethylene material was shorter than that from polytetrafluoroethylene felt (60.5 ± 4.81 versus 155 ± 6.59 seconds, p-value < 0.001 and 84.0 ± 8.51 versus 141.1 ± 7.02 seconds, p-value < 0.001). The tensile study showed that the prototype was significantly stronger than the slings conventionally made from polytetrafluoroethylene felt (6.2 ± 2.12 Newtons versus 1.56 ± 0.647 Newtons, p-value = 0.012). The adhesion study showed an equivalent adhesive strength to the conventional one (0.137 ± 0.05 Newtons versus 0.108 ± 0.05 Newtons, p-value = 0.40). The 39 microvascular decompression surgeries (trigeminal neuralgia, 13 cases; hemifacial spasm, 26 cases) showed no adverse events related to the materials (follow-up period: 9 months-3 years 9 months, mean: 2 years 9 months).

The new Pharmaceuticals and Medical Devices Agency-approved, refined polytetrafluoroethylene material, which is easier to handle and less time-consuming, exhibited uniform characteristics, excellent manipulability, sufficient strength, and clinical reliability for prostheses. It may serve as valuable additional option for prostheses in microvascular decompression surgery.

This study aimed to evaluate whether postoperative T2-weighted magnetic resonance imaging signal patterns can predict aneurysm shrinkage after surgery for large and giant intracranial aneurysms. We retrospectively analyzed 17 patients with large (10-24 mm) or giant (≥25 mm) cerebral aneurysms treated by clipping, trapping, or proximal ligation between 2009 and 2023. Postoperative aneurysmal signal intensity on T2-weighted magnetic resonance imaging was classified as homogeneous or heterogeneous. Aneurysm shrinkage was defined as a ≥50% reduction in maximum diameter at 2 years compared with the preoperative size. Changes in aneurysm diameter and signal patterns were assessed at 6 months, 1 year, and 2 years postoperatively. Statistical analyses included the Mann-Whitney U test for shrinkage rate and Fisher's exact test for categorical variables. In total, 13 aneurysms (76.5%) showed shrinkage, and 4 (23.5%) did not. The homogeneous group demonstrated a significantly greater reduction in aneurysm diameter than the heterogeneous group at 6 months (p = 0.002) and 1 year (p = 0.006), with a similar trend at 2 years (p = 0.051). Some aneurysms initially showing heterogeneous intensity later became homogeneous and subsequently decreased in size. In contrast, persistent heterogeneous signals were associated with poor shrinkage and, in 1 case, regrowth. Postoperative homogeneous signal intensity on T2-weighted magnetic resonance imaging was associated with aneurysm shrinkage, whereas heterogeneous intensity indicated incomplete thrombus organization and limited reduction. Postoperative magnetic resonance imaging signal patterns may serve as a simple imaging biomarker for evaluating thrombus stability and treatment efficacy after surgery for large and giant cerebral aneurysms.

The optimal management of lumbar spinal canal stenosis with spondylolisthesremains controversial, particularly when choosing between decompression alone or decompression with fusion. Current evidence is based on conventional open or endoscopy-assisted surgeries, with limited data on full-endoscopic decompression. This study aimed to assess the impact of spondylolisthesis on outcomes after full-endoscopic laminotomy by evaluating back pain-related disability scores in patients with lumbar spinal canal stenosis, with and without spondylolisthesis. A retrospective analysis was conducted at Iwai Orthopaedic Hospital, Japan. Patients with lumbar spinal canal stenosis who underwent full-endoscopic laminotomy between January 2021 and December 2022 were included and categorized into those without spondylolisthesis and those with spondylolisthesis. Postoperative Oswestry Disability Index scores at 2 years were compared in the groups using multivariable linear regression, adjusting for confounding factors. Exploratory analyses were also conducted to identify factors affecting the Oswestry Disability Index in the patients with lumbar spinal canal stenosis with spondylolisthesis group. Statistical significance was set at p < 0.05. The study included 80 patients, with 40 in each group. Both groups showed improved postoperative Oswestry Disability Index. There was no significant association between spondylolisthesis and postoperative Oswestry Disability Index. However, cauda equina redundancy negatively affected postoperative Oswestry Disability Index improvement in the patients with lumbar spinal canal stenosis with spondylolisthesis group. Full-endoscopic laminotomy is an effective surgical option for lumbar spinal canal stenosis, leading to significant alleviation of disability and improvements in quality of life, regardless of spondylolisthesis. Full-endoscopic laminotomy may offer similar functional improvements regardless of the presence of low-grade spondylolisthesis, supporting its role as a less invasive alternative to fusion.

In aging societies such as Japan, the number of patients aged ≥80 years with glioblastoma who are unsuited for surgery is rapidly increasing. At our institution, we adopted a therapeutic strategy based on clinical diagnosis without histological confirmation when surgery was not feasible. This study aimed to retrospectively evaluate the short-term outcomes and clinical value of surgical intervention and histological confirmation in this population. Patients aged ≥80 years diagnosed with glioblastoma between 2011 and 2025 were reviewed. Clinical diagnosis was applied when patients were unfit for surgery. Patient data, including age, sex, Karnofsky performance status, extent of resection, treatment options, and complications, were analyzed for associations with overall survival, Karnofsky performance status improvement, and discharge home. Among 203 cases, 31 patients (15.3%) were included. Their mean age was 84 years; the median Karnofsky performance status scores at admission and discharge were 50 and 60, respectively. Six patients underwent resection, 14 biopsy, and 11 clinical diagnosis. The clinical diagnosis group showed better functional outcomes, including improved Karnofsky performance status, shorter hospitalization, and higher discharge home rates than the biopsy group. Bevacizumab contributed significantly to these outcomes. Perioperative complications occurred in 4 patients; none recovered functionally or were discharged home. Low Karnofsky performance status at discharge was the only independent predictor of poor overall survival. Surgical intervention did not significantly affect the functional and survival outcomes. In conclusion, clinical diagnosis-based treatment, particularly with bevacizumab, could help preserve function and facilitate discharge in very elderly patients with glioblastoma. Biopsies might negatively impact the outcomes in the present cohort.

The recurrence of cerebral aneurysms after coil embolization remains a significant concern in clinical practice. This study introduced a novel approach that combines machine learning with deep learning techniques using time-of-flight magnetic resonance angiography to predict aneurysm recurrence. A retrospective multicenter analysis was conducted on 154 patients with coil-embolized unruptured cerebral aneurysms. Three prediction models were developed: a logistic regression model, a neural network model using clinical data, and a combined deep learning model incorporating both clinical and imaging data obtained from 3-dimensional reconstructed time-of-flight magnetic resonance angiography. The combined model was created in 2 versions: 1 trained exclusively with pre-operative images and the other using both pre- and post-operative images. All models were evaluated using leave-one-out cross-validation to assess the area under the receiver operating characteristic curve, accuracy, sensitivity, and specificity. Among the 154 cases, 46 (29.9%) demonstrated recurrence. The combined model that incorporated both pre- and post-operative time-of-flight magnetic resonance angiography images achieved the best discriminative performance, with an area under the receiver operating characteristic curve of 0.822 and sensitivity of 0.848, indicating a reliable capacity to identify patients at risk of recurrence. The version that used only pre-operative images showed relatively high accuracy (0.766) and specificity (0.833) but a lower overall area under the receiver operating characteristic curve. These results highlight the value of integrating time-of-flight magnetic resonance angiography data into artificial intelligence-driven predictive models to improve the assessment of recurrence risk after coil embolization. The improved performance of the combined model, particularly when including post-operative images, demonstrates potential for more precise, individualized risk prediction and may contribute to better patient management.

Cerebrospinal fluid-venous fistulas are increasingly recognized as a cause of spontaneous intracranial hypotension, particularly in patients who do not respond to conventional therapies. Although widely reported in Western populations, their prevalence and diagnosis in Asian cohorts remain underexplored. This study aimed to evaluate the utility of digital subtraction myelography in diagnosing cerebrospinal fluid-venous fistulas in Japanese patients with refractory spontaneous intracranial hypotension. We retrospectively analyzed adult patients with spontaneous intracranial hypotension who underwent digital subtraction myelography at our hospital between December 2024 and July 2025. The inclusion criterion was failure of 3 or more epidural blood patches. Digital subtraction myelography was performed using a standardized protocol with tilt-table positioning and contrast-enhanced imaging. The clinical and imaging data were reviewed. Ten patients (15 digital subtraction myelography studies) were included. Cerebrospinal fluid-venous fistulas were detected in 6 of 7 spinal longitudinal epidural collections-negative patients (85.7%). Spinal longitudinal epidural collections-positive patients (3/10) did not have cerebrospinal fluid-venous fistulas. Computed tomography after digital subtraction myelography demonstrated contrast accumulation in the renal pelvis in 88.9% of the cases with positive cerebrospinal fluid-venous fistula or spinal longitudinal epidural collection findings. One illustrative patient underwent Onyx embolization, resulting in marked symptom improvement. In this pilot study, cerebrospinal fluid-venous fistulas were found to be a relevant and treatable cause of refractory spontaneous intracranial hypotension in Asian patients. Digital subtraction myelography proved to be a valuable diagnostic tool, particularly in the absence of spinal longitudinal epidural collections on initial imaging.

The combined transpetrosal approach provides effective exposure to the petroclival region and ventral brainstem, although its technical demands necessitate advanced neurosurgical expertise. Proficiency in skull base drilling and meticulous separation of the dual dural layers is crucial. Recently, three-dimensional printing has gained attention as a tool for surgical training. To evaluate its potential in transpetrosal approach education, we developed a three-dimensional head model that reproduces the soft brain tissue, cranial nerves, vasculature, and tumors. A petrotentorial meningioma case was selected, and a corresponding three-dimensional model was generated using computed tomography and magnetic resonance imaging data. The skull base was printed using a three-dimensional printer. Liquid rubber-coated kitchen paper simulated the dura mater, wool yarn represented blood vessels, and rubber bands were used for cranial nerves. Ultra-soft polyurethane resin was employed to replicate the brain, brainstem, cerebellum, and tumor. Neurosurgeons practiced the combined transpetrosal approach on the model and completed a questionnaire evaluating anatomical accuracy and operative usability. Thirteen neurosurgeons participated. No statistically significant differences were found between those with experience in ≥5 combined transpetrosal approach and those with less experience. All participants gave favorable evaluations regarding the model's anatomical accuracy and its value for preoperative planning and surgical training. The model supported essential transpetrosal approach steps, including skull base drilling, dual-layer dural dissection, and tentorial incision, allowing for thorough practice of the combined approach. It offers a practical, realistic training platform that closely resembles actual surgical conditions.

Anatomical variations in the middle cerebral artery affect outcomes of mechanical thrombectomy in M1 occlusion cases. However, the relationship between middle cerebral artery branching patterns-specifically trifurcation and bifurcation-and mechanical thrombectomy outcomes remains unclear. This study investigated that relationship and attempted to identify optimal mechanical thrombectomy strategies for trifurcation patterns. We retrospectively analyzed patients treated with mechanical thrombectomy for M1 occlusion at our institution between 2019 and 2024. Patients were categorized into bifurcation and trifurcation groups based on middle cerebral artery branching patterns, and differences in outcomes between the groups were analyzed. In the trifurcation group, further analysis compared characteristics between patients with and without successful recanalization, defined as a modified Thrombolysis in Cerebral Infarction score of 2b-3. Among 98 patients (trifurcation, n = 21; bifurcation, n = 77), the trifurcation group showed lower successful recanalization rates (57% vs. 91%, p = 0.001) and higher procedural complication rates, including distal thrombus migration (62% vs. 36%, p = 0.047) and symptomatic intracerebral hemorrhage (38% vs. 14%, p = 0.027), compared with the bifurcation group. A multivariate modified Poisson regression demonstrated that the trifurcation pattern was independently associated with reduced successful recanalization (relative risk = 0.22; 95% confidence interval, 0.09-0.53; p = 0.001). In trifurcation cases, contact aspiration achieved higher successful recanalization rates than the combined technique (100% vs. 44%, p = 0.009). Moreover, in combined technique cases, direct contact between the aspiration catheter and thrombus significantly improved recanalization rates (77% vs. 0%, p < 0.001) without increasing complications. Trifurcation anatomy hindered effective clot engagement by the aspiration catheter because of narrow M2 diameters and large branching angles, resulting in lower successful recanalization rates compared with bifurcation.

Subarachnoid hemorrhage is a life-threatening cerebrovascular event, and cerebral vasospasm remains a major cause of poor neurological outcomes. Clazosentan, an endothelin-A receptor antagonist, has been recently approved in Japan to reduce post-subarachnoid hemorrhage vasospasm; however, recurrent vasospasm after cessation of therapy has occasionally been reported, which underlying mechanisms remain unclear. Moreover, endothelin-A receptor is also expressed on pericytes; however, the effects of clazosentan on microvascular endothelin-A receptor remain unexplored. In this study, we employed a rat subarachnoid hemorrhage model to investigate the temporal dynamics of vasospasm and endothelin-A receptor expression in both large arteries and microvessels, and to evaluate the effects of clazosentan administration. Sprague-Dawley rats were assigned to naïve controls, subarachnoid hemorrhage with saline, or subarachnoid hemorrhage with continuous clazosentan administration for 7 days via osmotic pumps. Vasospasm was assessed by arterial wall thickness, and endothelin-A receptor expression was quantified using immunohistochemistry and immunofluorescence, including staining with α-SMA, CD31, and PDGF-β. Clazosentan significantly attenuated vasospasm in the middle and anterior cerebral arteries, and recurrent vasospasm was observed 3 days after cessation of clazosentan, coinciding with sustained upregulation of endothelin-A receptor in these vessels. In microvessels, pericyte density transiently decreased, peaking at a nadir on day 3 post-subarachnoid hemorrhage, while endothelin-A receptor expression on pericytes was highest at the same time point, and further elevated by clazosentan treatment. These findings indicate that clazosentan induces endothelin-A receptor upregulation in both macro- and microcirculation, potentially contributing to recurrent vasospasm after treatment, and highlight the critical role of pericytes in post-subarachnoid hemorrhage vascular regulation.

This study evaluated 14 patients who underwent robot-assisted deep brain stimulation electrode implantation and described our early experiences and workflows in both awake and asleep states. The deep brain stimulation targets included the subthalamic nucleus (n = 6), anterior thalamic nucleus (n = 5), and globus pallidus internus (n = 3). The patient was placed in the supine position, and the ROSA system was affixed diagonally onto the Leksell head frame to align with the X-ray system. Registration was performed at the center of each Leksell pin opening. In some patients with globus pallidus internus-deep brain stimulation, we performed semi-microelectrode recording to confirm the inferior border of the globus pallidus internus even under general anesthesia. In all patients with subthalamic nucleus-deep brain stimulation, semi-microelectrode recording was used to confirm the subthalamic nucleus location under local and intravenous anesthesia. In patients with anterior thalamic nucleus-deep brain stimulation, we used several methods for burr holes to avoid cerebrospinal fluid leakage as much as possible because of the trajectories running through the lateral ventricles. Deep brain electroencephalography was performed after the electrodes were inserted into the anterior thalamic nucleus. Deep brain stimulation implantation using the ROSA system was performed smoothly without any trouble in all patients. No intraoperative complications or major complications were reported immediately after deep brain stimulation. This study represents the first reported experience with ROSA-assisted deep brain stimulation in Japan and supports its broader application in awake or asleep state, and with or without semi-microelectrode recording.

In Japan, which has become a super-aging society, the incidence of spontaneous intracerebral hemorrhage among older adults is increasing. Managing these patients is often complicated by frailty and systemic comorbidities. Although these issues pose unique challenges, there is limited research on spontaneous intracerebral hemorrhage in this population, leaving their clinical characteristics and prognoses unclear. This retrospective study reviewed spontaneous intracerebral hemorrhage patients aged ≥75 years who were admitted to our institution from April 2004 to March 2024. Demographics, clinical presentation, imaging findings, and in-hospital outcomes were analyzed to identify risk factors for both 30-day and complication-related mortality. A total of 501 patients were included in the study, with 213 (42.5%) categorized as the oldest-old (age ≥85 years). Over the 2-decade study period, the proportion of oldest-old spontaneous intracerebral hemorrhage patients increased, and this age group exhibited a high risk of complication-related mortality (16.9%). Multivariate analysis identified age ≥85 years (odds ratio: 4.25, 95% confidence interval: 2.12-8.51, p < 0.001), Glasgow Coma Scale score ≤8 at admission (odds ratio: 2.27, 95% confidence interval: 1.19-4.34, p = 0.013), and serum albumin ≤3.5 g/dL at admission (odds ratio: 2.12, 95% confidence interval: 1.07-4.19, p = 0.031) as independent risk factors for complication-related mortality. The prognosis of spontaneous intracerebral hemorrhage in older adults is significantly worse in individuals aged ≥85 years. Older patients with spontaneous intracerebral hemorrhage are at a heightened risk of complication-related mortality, which is primarily associated with advanced age, neurological severity, and hypoalbuminemia.

Although the efficacy of endovascular therapy for large-vessel occlusion is well-established, its effectiveness in the M2 segment of middle cerebral artery occlusion remains uncertain. This study aimed to identify which M2 segment of middle cerebral artery occlusion cases may benefit from endovascular therapy by focusing on the first-pass effect, which refers to patients who underwent endovascular therapy and achieved complete reperfusion after 1 pass. The study analyzed computed tomography perfusion imaging using the Rapid Processing of Perfusion and Diffusion software. In this retrospective study, we analyzed 71 patients with M2 segment of middle cerebral artery occlusion who underwent endovascular therapy after computed tomography perfusion imaging using the Rapid Processing of Perfusion and Diffusion software. The patients were divided into 2 groups: the first-pass effect group (n = 15) and the No first-pass effect group (n = 56). The first-pass effect group showed a significantly higher proportion of patients with a modified Rankin Scale score of 0-2 at 90 days than the No first-pass effect group (80.0% vs. 39.3%; adjusted odds ratio: 12.6, 95% confidence interval: 1.27-125.5). Among Rapid Processing of Perfusion and Diffusion-derived parameters, a median Hypoperfusion Intensity Ratio, an index of collateral status, was significantly lower in the first-pass effect group, with a suggested threshold of <0.22. In patients with M2 segment of middle cerebral artery occlusion, achieving first-pass effect was associated with better neurological outcomes. First-pass effect was more likely when Hypoperfusion Intensity Ratio was ≤ 0.22, suggesting this parameter may guide treatment decisions.

This study investigated the hemodynamic effects of anastomosis site selection in superficial temporal artery to middle cerebral artery bypass surgery using computational fluid dynamics based on three-dimensional cerebral vascular models. By noninvasively reproducing blood flow changes that are difficult to evaluate in clinical settings, we visualized and quantified the effects of different bypass locations under both normal and stenotic conditions. To our knowledge, this is the first study to noninvasively evaluate the validity of anastomosis site selection in superficial temporal artery to middle cerebral artery bypass surgery using computational fluid dynamics simulation. The results demonstrated that factors, such as the distance from the anastomosis site to the target territory, flow direction, recipient vessel diameter, and pressure gradient, significantly influenced cerebral perfusion. In particular, bypass configurations that ensured antegrade flow, minimized the distance to the target region, and involved a larger recipient vessel diameter showed greater improvement in blood flow. These findings offer practical guidance for preoperative planning and are expected to contribute to the safer and more effective selection of bypass sites.