Although chronological age is an important factor in indications and predicting outcomes of neurosurgery, it is essential to consider biological age, particularly in older patients, due to individual differences such as frailty. The simplified 5-factor modified frailty index has recently been introduced. This study investigated its role in predicting the outcomes of meningioma and unruptured cerebral aneurysm surgery by analyzing data from the Diagnosis Procedure Combination database in Japan from 2010 to 2014. Although the 5-factor modified frailty index scores could predict the risk of in-hospital worsening outcomes, mortality, and complications in meningioma surgery, it was more useful in non-elderly patients aged <65 years rather than in elderly patients aged ≥75 years. Additionally, in patients aged <74 years, in-hospital complications of unruptured cerebral aneurysms were more associated with the 5-factor modified frailty index than with chronological age.

Alternatively, in patients with aneurysmal subarachnoid hemorrhage, previous reports have suggested a non-linear correlation between age and the outcome, but no reports have explored this relationship. Therefore, we visualized a clear non-linear correlation between age and poor outcomes, which can aid clinical decision-making and better inform and guide patients with aneurysmal subarachnoid hemorrhage and their families. We could validate this visualization using a separate cohort based on the discrimination property and calibration plot. Progress has been made in predicting outcomes for older patients undergoing neurosurgery in Japan; however, in the future, more individualized and specific predictions will be required.

Full-endoscopic trans-Kambin's triangle lumbar interbody fusion is considered a minimally invasive procedure. The cage position in Kambin's triangle lumbar interbody fusion differs from that in other types of lumbar interbody fusion; the cage is inserted via the foramen and placed diagonally to the endplate. Therefore, the ideal cage position remains uncertain. This study evaluated the biomechanical effects of different cage positions in Kambin's triangle lumbar interbody fusion at L4/5. An intact lumbar-to-femur finite element model was constructed. A diagonal line was first set with the foramen as the starting point, and this was used as the reference line [K(0°)] for the cage insertion angle. Five insertion angles were set: 10° and 20° anteriorly [K(10°) and K(20°)], 0° [K(0°)], and 10° and 20° posteriorly [K(−10°) and K(−20°)]. Range of motion and von Mises stress at the endplate were measured with the cage placed anteriorly, in the middle, and posteriorly for each angle (15 cage positions total). The mean range of motion at L4/5 was smallest for the middle cage position at K(0°) [K(0°)-Middle], followed by K(10°)-Middle. Endplate stress at L5 was 25.2 and 23.3 MPa for K(0°)-Middle and K(10°)-Middle, respectively (83.5 and 77.1% of the average for the 15 cage positions). Considering the range of motion and endplate stress, a central cage position [K(0°)-Middle and K(10°)-Middle] can effectively enhance stiffness at the fused segment, thereby contributing to stability. Moreover, reducing endplate stress at L5 may lower the risk of endplate collapse and cage subsidence. Therefore, it is desirable to place the cage in the center or slightly anterior to the center.

The subarcuate artery, a branch of the anterior inferior cerebellar artery, has traditionally been considered a nonessential vessel whose sacrifice during cerebellopontine angle surgery is believed to produce no sequelae. Despite anatomical studies documenting the course and distribution of the subarcuate artery, no clinical reports have directly linked subarcuate artery injury to hearing impairment, reinforcing this traditional understanding. We retrospectively analyzed 3 cases of hearing impairment following subarcuate artery injury during microvascular decompression procedures, drawn from a series of 109 surgeries performed between January 2011 and December 2024 at our institution. All patients underwent continuous intraoperative auditory brainstem response monitoring, with detailed documentation of vascular events and corresponding signal changes. In all cases, intraoperative assessment confirmed that the labyrinthine artery remained intact, whereas the subarcuate artery was compromised. Each patient showed delayed auditory brainstem response deterioration, with complete signal loss occurring within 15-20 min after subarcuate artery manipulation. In 2 cases, deliberate transection or inadvertent avulsion of the subarcuate artery resulted in complete and permanent hearing loss. In the third case, a bleeding subarcuate artery was managed using compression hemostasis without coagulation, and serviceable hearing was preserved. To the best of our knowledge, this is the first clinical evidence that subarcuate artery injury can lead to hearing impairment, challenging the conventional understanding. The delayed auditory brainstem response deterioration pattern suggests that subarcuate artery injury affects inner ear perfusion through anastomotic connections with the labyrinthine artery, particularly in patients with anatomical variations. Therefore, we recommend preserving the subarcuate artery whenever possible to minimize the risk of postoperative hearing deficits.

Talk and Deteriorate refers to a clinical course where a patient is able to speak immediately after a traumatic brain injury but subsequently deteriorates in consciousness. Talk and Deteriorate outcomes are poor, and reliable prediction may help improve them. We searched for multifactorial biomarkers-combinations of multiple risk factors-assuming they would predict Talk and Deteriorate more reliably than single factors. A total of 680 consecutive patients aged ≥16 years with intracranial traumatic lesions and a Glasgow Coma Scale of 13-15 upon admission were included. Information on 27 factors at admission and whether Talk and Deteriorate developed was collected. The correlation between Talk and Deteriorate incidence and each factor was evaluated using univariate analysis. Multifactorial biomarkers associated with a high Talk and Deteriorate incidence were identified using a brute force method combined with clustering based on combinations of factors and various thresholds for each. Among the 680 patients, 89 (13.1%) developed Talk and Deteriorate. A total of 94 multifactorial biomarkers with a Talk and Deteriorate incidence rate of ≥50.0% were identified. These multifactorial biomarkers, which included factors previously suspected to be related to Talk and Deteriorate, were associated with a higher Talk and Deteriorate incidence than each factor alone. Thus, this study indicates that predicting Talk and Deteriorate is more reliable when based on multifactorial biomarkers than on single factors. Factors not previously reported as independent biomarkers contributed as components of multifactorial biomarkers, while previously reported factors played more important roles within them. Thus, this study revealed multifactorial contributions of factors related to Talk and Deteriorate. Future studies focusing on these biomarkers, incorporating pathophysiologic insights, will improve Talk and Deteriorate outcomes.

The surgical complexity of microvascular decompression for hemifacial spasm was evaluated based on procedure duration. A retrospective analysis was performed on 127 patients who underwent microvascular decompression for hemifacial spasm. Surgical time was divided into 3 phases: craniotomy, microscopic procedure, and closure. Durations were analyzed by age, sex, body mass index, and whether mastoid air cells were opened. Microscopic procedure times were further assessed by mobilization of the anterior inferior cerebellar artery, posterior inferior cerebellar artery, and vertebral artery, as well as the number of arteries mobilized (single vs. multiple). Total surgical time was significantly shorter in patients aged ≥65 years (p = 0.015) and in women (p < 0.001). Sex was significantly associated with both craniotomy and closure durations (p < 0.001). Closure time was longer when mastoid air cells were opened (p = 0.013). Microscopic procedure time was also shorter in older patients (p = 0.001). No significant differences were observed between anterior inferior cerebellar artery- and posterior inferior cerebellar artery-related cases (p = 0.204 and p = 0.603). Vertebral artery-related cases tended to require longer durations, though not significantly (p = 0.085). Multiple artery mobilization showed a similar trend (p = 0.068). In 4 cases, microscopic time exceeded 100.5 mins due to overlapping factors such as bleeding, dense arachnoid, interfering perforators, and limited surgical space. Craniotomy and closure may be more complex in male patients with large mastoid air cells, and intradural complexity should be anticipated regardless of the culprit artery.

Far-out syndrome is a pathological condition characterized by entrapment of the L5 nerve root by the L5 transverse process, sacral ala, vertebral body, and adjacent soft tissue. Although many cases of far-out syndrome have been reported, a standardized surgical approach has not yet been fully established. As older adults are often affected by this condition, full-endoscopic spine surgery may be a preferable option due to its minimally invasive nature.

This case series included six far-out syndrome cases treated with full-endoscopic spine surgery at our hospital. Patient background and operative data were collected from medical records. The numerical rating scale scores for pain and numbness, and the modified MacNab criteria, were recorded for 1 year postoperatively.

The mean age was 73.5 years, and the mean duration of symptoms was 46.5 months. The mean operative time was 62.7 min without complications. In five of six cases, the amount of intraoperative bleeding was lower than the measuring limit in our hospital. The numerical rating scale score for pain improved at 1 year after surgery in all cases except case 6, who sustained a vertebral compression fracture 11 months after full-endoscopic spine surgery. According to the modified MacNab criteria, excellent or good outcomes were observed in five cases (83%) except for case 6.

Full-endoscopic spine surgery for far-out syndrome appears to offer not only minimal invasiveness but also satisfactory surgical outcomes.

The long-term efficacy of clipping unruptured intracranial aneurysms via various keyhole mini-craniotomy procedures was evaluated. A retrospective review was conducted on 350 unruptured intracranial aneurysms (6.1 ± 1.9 mm) in 330 patients (218 women and 112 men, mean age 62 ± 10 years) located in the anterior circulation and clipped via various keyhole mini-craniotomy procedures between July 2005 and December 2023. modified Rankin Scale and Mini-Mental State Examination were evaluated. Anxiety and depression were assessed using the Beck Depression Inventory and the Hamilton Rating Scale for Depression. The state of clipping was assessed by computed tomography angiography at 1 year and at intervals of a few years. The mean size of the craniotomy was 26.5 ± 3.4 mm and the complete neck clipping rate was 96.9%. The mean postoperative hospitalization was 2.7 ± 3.6 days. Two patients (0.6%) experienced symptomatic lacunar infarctions. Surgical morbidity (modified Rankin Scale >2 or Mini-Mental State Examination <24) at 3 months, 1 year, and at the last examination (mean 6.6 ± 4.4 years) was 0.9%, 1.5%, and 1.8%, respectively. Neither neurological state nor cognitive function changed significantly during the follow-up period. Anxiety and depression states improved significantly at 3 months after surgery. During radiological follow up (mean 7.1 ± 4.6 years, range 1-19 years), the rates of regrowth of aneurysm remnant, recurrence, retreatment, and rupture were 18.1% (1.6%/year), 0.9% (0.1%/year), 0.9% (0.1%/year), and 0.3% (0.04%/year), respectively. Our study confirmed that keyhole clipping of unruptured intracranial aneurysm had low morbidity, early recovery in anxiety and depression, and very low aneurysm recurrence and retreatment rates, indicating that this modality is substantially curative.

This retrospective cohort study investigated the association between the use of clazosentan and the incidence of symptomatic vasospasm, as well as rehabilitation-related outcomes, particularly, the timing of ambulation, in patients with aneurysmal subarachnoid hemorrhage. A total of 153 patients who underwent surgical clipping or endovascular coiling at our institution between January 2020 and March 2025 were included; among them, 76 received clazosentan, and 77 received conventional treatment.

The primary outcomes were the incidence of symptomatic vasospasm and the number of days to initial ambulation. Secondary outcomes included changes in body weight, peripheral oxygen saturation, and laboratory parameters one week after drug administration.

The incidence of symptomatic vasospasm was significantly lower in the clazosentan group (5.3%) than in the conventional treatment group (20.7%) (p = 0.007). In addition, ambulation was achieved significantly earlier in the clazosentan group (median: 8.5 days; interquartile range: 5–12) than in the control group (median: 11 days, interquartile range: 8–15) (p = 0.015).

Conversely, one week after administration, the clazosentan group showed a significant increase in body weight and significant decreases in peripheral oxygen saturation, serum albumin, hemoglobin, and hematocrit levels, suggesting potential systemic effects.

These findings suggest that clazosentan use may be associated with a lower incidence of symptomatic vasospasm and earlier ambulation in patients with aneurysmal subarachnoid hemorrhage; however, careful monitoring of systemic status is warranted during rehabilitation.

Andexanet alfa was approved as a reversal agent for Factor Xa inhibitors in patients with uncontrolled or life-threatening bleeding, such as intracerebral hemorrhage. However, its use in cases of small hemorrhages remains controversial. This study determined the appropriate use of andexanet alfa on the basis of hematoma volume and location analysis. The study included consecutive patients with intracerebral hemorrhage who took Factor Xa inhibitors between January 2020 and December 2024. Individuals receiving standard care (January 2020-June 2022) and those being administered andexanet alfa (July 2022-December 2024) were compared and classified by hematoma volume (<5 mL, 5-30 mL, and >30 mL). Sixty-one patients were enrolled, with 27 and 34 patients receiving standard care and andexanet alfa care, respectively.

Excellent hemostasis (hematoma increase <20%) and preserved neurological findings (National Institutes of Health Stroke Scale change <4) were achieved in patients treated with andexanet alfa compared with patients who received standard care (p = 0.0007, p = 0.004). For middle-sized (5-30 mL) and large-sized (>30 mL) hematomas, the rate of patients with excellent hemostasis in andexanet alfa care was significantly higher than that of patients in standard care (p = 0.032, p = 0.035). Among small hematomas, those in the thalamus or brainstem were significantly associated with neurological deterioration due to hematoma expansion. Andexanet alfa prevented hematoma expansion in these regions of small hematomas (p = 0.0285). In conclusion, small hematomas located in deep regions such as the thalamus or brainstem and bigger than those in any location should be considered for treatment with andexanet alfa as a reversal agent of Factor Xa inhibitors.

The transradial/transbrachial approach for mechanical thrombectomy offers potential reductions in access-site complications, but the feasibility of downsizing to a 4 Fr guiding sheath remains to be systematically assessed. To evaluate the feasibility and safety of mechanical thrombectomy performed through a 4 Fr transradial/transbrachial approach in selected patients and to compare procedural metrics with those of a contemporaneous transfemoral approach cohort treated at the same center, we retrospectively reviewed consecutive patients who underwent mechanical thrombectomy between December 2023 and December 2024. Overall, 17 patients were treated with a 4 Fr sheath through the right transradial/transbrachial approach and 87 with transfemoral approach. Baseline demographics, procedural times, recanalization rates, and access-site complications were compared using the Mann-Whitney U or χ² tests, as appropriate. Successful recanalization (modified Thrombolysis in Cerebral Infarction grade ≥ 2b) was achieved in 14 of 17 cases (82%) in the 4 Fr group, comparable to 78 of 87 cases (90%) in the transfemoral approach group (p = 0.39). Median puncture-to-recanalization time was 34 min (interquartile range 27.8-67) versus 36 min (interquartile range 23-56.5) (p = 0.78). No symptomatic intracranial hemorrhage occurred in the 4 Fr cohort. Access-site complications were limited to 1 minor superficial hematoma (6%), whereas the transfemoral approach group experienced 3 access-site events (3.4%), all pseudoaneurysms. A 4 Fr transradial/transbrachial approach for mechanical thrombectomy is feasible and indicates a favorable safety profile without prolonging procedure time in carefully selected right-sided or posterior circulation lesions with low thrombus burden. Larger prospective studies are warranted to confirm these signals and to explore applicability to broader patient populations.

During mechanical thrombectomy, manipulation under the limited visibility of vessels distal to the occlusion site could result in vessel perforation. Standard imaging techniques such as magnetic resonance imaging and digital subtraction angiography often fail to reveal detailed structures beyond the occlusion site. Aortic cone-beam computed tomography, that is cone-beam computed tomography performed using an intraarterial injection of contrast medium from the ascending aorta, has the potential to overcome this limitation by providing a comprehensive view of intracranial vessels. This study investigated whether aortic cone-beam computed tomography could better visualize distal vessels beyond occlusion than other modalities. This retrospective cohort study included patients with acute ischemic stroke who underwent mechanical thrombectomy during 2020-2024. The visibility of distal vessels was scored on a 5-point scale according to the visualized segment of vessels beyond the occlusion site (1 indicates excellent, and 5 indicates poor) and then compared between aortic cone-beam computed tomography and conventional imaging techniques, including digital subtraction angiography and magnetic resonance imaging, using the Wilcoxon signed-rank test. This study included 100 patients. Aortic cone-beam computed tomography resulted in a median visibility score of 2, which was better than those obtained by digital subtraction angiography (2 vs 3, p < 0.001) and magnetic resonance imaging (2 vs 5, p < 0.001). Aortic cone-beam computed tomography improves the visibility of distal vessels beyond occlusion than magnetic resonance imaging and digital subtraction angiography. This may help in safe procedures during mechanical thrombectomy.

Titanium plates and meshes are frequently used to secure bone flaps or to reconstruct defects after craniectomy. Although generally effective, they are occasionally associated with delayed skin complications. This study aimed to identify clinical features of delayed exposure of titanium implants. We retrospectively reviewed 29 patients with titanium implant exposure ≥1 year after cranioplasty or craniotomy (12 with titanium meshes and 17 with titanium plates) treated at our institution between January 2000 and December 2021. Patient characteristics (age, sex, initial disease, multiple surgeries, radiation therapy, diabetes mellitus, body mass index, and interval from the most recent surgery to implant exposure) were compared in the 2 groups. The relationship among the location of skin complications, implant placement, and original surgical incision line was also evaluated. Implant exposure was more frequent in female patients (82.8%). The median interval was significantly shorter in the mesh group than in the plate group (3.9 years vs. 12.0 years, respectively); 82.4% of plate-related exposures were located directly under previous incision, whereas mesh-related exposures tended to occur away from incisions. In both groups, more than 90% of lesions developed in areas lacking muscle coverage; 47.1% of titanium plate exposure was found over the linea temporalis and directly beneath incision lines. In conclusion, titanium implants-particularly in female patients and in those placed beneath incision lines or in areas lacking muscle coverage-are associated with an elevated risk of delayed exposure. Surgical planning should carefully consider implant positioning to reduce long-term complications.

One-stage tumor resection and cranioplasty for skull tumors using custom-made implants are beneficial for reducing patient burden, minimizing complications, and improving cosmetic outcomes. However, accurately determining the craniotomy line remains challenging. This technical note describes a method for integrating implant design data into a navigation system to facilitate accurate 1-stage surgery for skull and scalp tumors. Merged images of the implant design data and preoperative computed tomography scans were created. The craniotomy line was determined using a navigation system with merged images. After tumor resection, cranioplasty was performed using a custom-made implant. We applied this technique in 2 patients with metastatic skull tumors and 2 with primary scalp sarcomas with skull invasion. Gross total resection was achieved in all patients. The resection area was expanded beyond the preplanned margins in 2 cases because of tumor progression; the bone defects were filled or covered with bone cement or titanium plates, with positive cosmetic results. The alignment between the implants and skull was satisfactory, and no postoperative complications were observed. This technique enables accurate, efficient, and safe 1-stage surgery by ensuring precise osteotomy and optimal implant fitting in skull and scalp tumors.