Masaomi Koyanagi

Objective: To compare long-term hemorrhagic and functional outcomes between intervention and observation for brain arteriovenous malformations (bAVMs). Methods: We performed a retrospective, single-center cohort study of angiographically confirmed bAVMs, ruptured and unruptured, evaluated between 2000 and 2025. Initial management was observation or intervention (embolization, microsurgery, stereotactic radiosurgery or multimodal therapy). The primary endpoint was any bAVM-related intracranial hemorrhage from diagnosis, including perioperative and follow-up events; secondary endpoints included follow-up hemorrhage, perioperative hemorrhage and a favorable functional outcome at last follow-up (modified Rankin Scale (mRS) 0–2). Kaplan-Meier and multivariable Cox regression were used, with inverse probability of treatment weighting and time-dependent analyses to assess robustness. Results: Of the 337 screened patients, 220 were eligible (108 ruptured, 112 unruptured); 138 (63%) underwent initial intervention and 82 (37%) were observed. Over 1943 patient-years (median, 7.4 (IQR, 1.9–14) years), 28 follow-up hemorrhages and 13 perioperative hemorrhages occurred. For the primary endpoint, 10-year hemorrhage-free survival was 66% (observation) versus 93% (intervention; log-rank p<0.001). The annual follow-up hemorrhage rates were 3.2% and 0.4% in the observation and intervention groups, respectively. Intervention was independently associated with a lower risk of follow-up hemorrhage, with similar estimates across models and in ruptured and unruptured bAVMs. At the last follow-up, 74% of patients in the intervention group and 68% in the observation group had an mRS score of 0–2. Conclusions: Compared with observation, intervention for bAVMs was associated with lower long-term hemorrhagic risk, without worse functional outcomes. These findings support individualized, multidisciplinary treatment decisions.

Background/Objectives: Recent randomized controlled trials (RCTs) have not demonstrated the efficacy of me-chanical thrombectomy (MT) for medium vessel occlusion (MeVO), partly due to device selection bias. Notably, small-bore aspiration catheters were not evaluated. This study aimed to assess the safety and efficacy of the ADAPT (A Direct Aspiration First Pass Technique) approach using small-bore aspiration catheters as a first-line treatment for MeVO. Methods: We conducted a retrospective, single-center cohort study of patients who underwent MT for MeVO between March 2023 and April 2025. Patients were categorized based on the initial thrombectomy technique: ADAPT versus stent retriever (SR) or combined ap-proaches. The primary efficacy outcome was successful reperfusion, defined by the ex-panded Thrombolysis in Cerebral Infarction (eTICI) score. The primary safety outcome was the incidence of device-related adverse events. Results: A total of 54 consecutive MeVO cases were identified, comprising 9 cases treated with ADAPT (with small-bore aspiration catheters used in 89% of these) and 45 cases treated with stent retriever or combined techniques. Successful reperfusion (eTICI ≥2b50) was achieved in 100% of the ADAPT group and eTICI ≥2b67 in 77.8%. The ADAPT group showed a significantly higher rate of eTICI ≥2b50 (p < 0.05) and a lower incidence of device-related complications (odds ratio: 1.82 × 10⁻⁹; p = 0.029) compared to the SR/combined group. Conclusions: The ADAPT using small-bore aspiration catheters demonstrated high reperfusion success and a lower risk of device-related complications, suggesting it may serve as an effective first-line strategy for MeVO treatment.

Background: Mechanical thrombectomy (MT) is an important treatment for middle cerebral artery (MCA) M2 occlusions. However, it carries a risk of intracranial hemorrhage (ICH), especially with a stent retriever. We investigated the correlation between MCA M1 tortuosity and ICH after MT using a stent retriever for M2 occlusions, along with other clinical outcomes. Methods: This single-center, retrospective study included patients with isolated MCA M2 occlusions treated using a stent retriever. M1 tortuosity was assessed using pre-MT imaging, with patients classified into tortuous (≥ 2 angulations) and non-tortuous (≤ 1 angulation) groups. The primary outcome was any ICH. Secondary outcomes included symptomatic ICH (sICH), procedural outcomes, and functional outcomes. Results: Among 153 patients (median age: 78 years, 48% female), 55 (36%) had tortuous M1 segments. The tortuous group showed higher NIHSS scores (median score 19 vs. 14, p = 0.045) and a higher prevalence of chronic renal failure at baseline (15% vs. 4%, p = 0.029). Any ICH occurred in 69 patients (45%) and was more frequent in the tortuous group (64% vs. 35%, p = 0.003; adjusted odds ratio [aOR], 3.09; 95% confidence interval [CI], 1.48–6.42). Among the ICH subtypes, subarachnoid hemorrhage (SAH) was more common in the tortuous group (49% vs. 27%, p = 0.01; aOR, 2.61; 95% CI, 1.26–5.41). However, the incidence of sICH (5.5% vs. 4.1%, p = 0.70) and good neurological outcome at 90 days after MT (45% vs. 50%, p = 0.62) were comparable. Conclusion: MCA M1 tortuosity was associated with a higher incidence of any ICH, particularly SAH, after MT using a stent retriever for M2 occlusions.

Brain arteriovenous malformations (bAVMs) are uncommon vascular lesions found in young individuals exhibiting diverse clinical manifestations ranging from asymptomatic to spontaneous intracranial hemorrhage, seizures, or headaches. Despite improvements in endovascular tools and methods, standalone transarterial embolization seldom achieves success rates surpassing 50%, even when employing ethylene vinyl alcohol copolymers. Transvenous embolization (TVE) emerges as a promising option, especially for bAVMs situated distally or inaccessible through arterial routes. Despite the possibility of achieving high angiographic cure rates, concerns regarding hemorrhagic complications persist, limiting its adoption. This review article outlines the indications and methodology of TVE, discusses complications, and highlights the essential expertise needed for the safe execution of TVE along with strategies to mitigate associated risks. Clinical results reveal promising outcomes in terms of obliteration rates and favorable neurological results, although challenges persist, particularly regarding device accessibility and risk management. Despite these challenges, TVE remains a valuable alternative for managing bAVMs, particularly for cases resistant to surgical intervention, emphasizing the significance of careful patient selection and procedural expertise.

Background: Nervous system involvement in immunoglobulin G4-related disease (IgG4-RD) has been rarely reported. Case Description: We describe an unusual case of IgG4-RD manifested as paresthesia in the right lower extremity. A 51-year-old male presented with paresthesia in the right S1–S3 regions. A neurological examination revealed peripheral neuropathy. Blood examination results were normal, barring slightly elevated IgG levels. Initial magnetic resonance imaging of the swollen right S1 and S2 nerve roots revealed lymphoma, schwannoma, and sarcoidosis. However, following the biopsy, the pathological findings were not typical of these diseases. Abdominal computed tomography revealed perirenal lesions, and IgG4-RD was suspected. The patient had a serum IgG4 level of 724 mg/dL. Additional pathological evaluations of the swollen S1 nerve revealed findings that corresponded to the diagnostic criteria for IgG4-RD. Oral steroid therapy was initiated, which improved paresthesia, and the swollen S1 nerve root gradually shrank. Conclusion: This report highlights a rare case of IgG4-RD involving nerve roots that neurosurgeons should consider.

Introduction: We investigated whether apixaban is safe for the prevention of further adverse events in non-valvular atrial fibrillation (NVAF) patients with intra-/extracranial artery stenosis (Stenosis group) compared with acute large vessel occlusion without intra-/extracranial artery stenosis (No stenosis group). We also examined whether combination therapy using apixaban and antiplatelet is safe. Methods: ALVO (Apixaban on clinical outcome of patients with Large Vessel Occlusion [LVO] or stenosis) was a historical and prospective multicenter registry at 38 centers in Japan. Patients with NVAF and acute LVO or stenosis who received apixaban within 14 days after onset were included. We conducted the post hoc analysis using the ALVO dataset. We compared patients with stenosis versus those without stenosis in terms of the primary outcome, which was defined as a composite of all-cause death, major bleeding events, and ischemic events 365 days after onset. Results: Of the 662 patients, 54 (8.2%) patients were classified into the Stenosis group, and 104 patients of the total (16%) reached the primary outcome. The cumulative incidence of primary outcome was not significantly different between the No stenosis and the Stenosis groups (hazard ratio [HR] 1.2, 95% confidence interval [CI]: 0.64–2.4; p = 0.52). Even after adjustment for predictive clinical variates, no significant difference in the primary endpoint between the No stenosis and the Stenosis groups was shown (adjusted HR 1.2, 95% CI: 0.59–2.5; p = 0.60). Fifty patients (7.6%) used an antiplatelet with apixaban. Among the Stenosis group patients, the cumulative incidence of the primary outcome was significantly higher among patients treated with an antiplatelet and apixaban (HR 3.5, 95% CI: 1.0–12; p = 0.048). Conclusion: Apixaban monotherapy appears safe for the prevention of further adverse events in the Stenosis group patients similar to the No stenosis group patients. Concomitant use of an antiplatelet might not be favorable in patients with stenosis.