Objective: Mechanical thrombectomy (MT) is an important procedure in the treatment of acute cerebral infarction, and its effectiveness depends largely on timely intervention after the onset. In the United States, a tiered accreditation system of stoke centers has been established to provide MT efficiently. In Japan, however, despite the large number of medical institutions performing MT, the establishment of a tiered accreditation system has yet to be seen. The low number of cases treated per institution raises concerns about the economic sustainability of MT in Japan because significant capital and human resource investment are required. This study aims to investigate the cost structure of MT procedure and the break-even point in 2 different hospital settings in Japan.

Methods: We conducted a detailed cost analysis of MT at 2 distinct hospitals: Hospital A, a large public hospital in a government-designated city, and Hospital B, a private non-profit hospital in the Tokyo metropolitan area. Data collection involved face-to-face interviews with department heads and a structured survey based on the Japanese Hospital Accounting Standards, focusing on material, labor, and facility-related costs. Break-even points were calculated considering both fixed and variable costs, with adjustments made for the shared use of facilities in Hospital B.

Results: The total cost per case was 349256 yen in Hospital A and 245150 yen in Hospital B, respectively. The total cost per case was elevated to 559866 yen assuming only MT was performed at Hospital B. This figure was significantly higher than the reimbursement price of MT (331500 yen). The number of procedures needed to exceed the break-even point for MT was approximately 290 cases per year in Hospital A and 125 cases per year in Hospital B, respectively.

Conclusion: We conducted a break-even analysis of MT based on an interview survey. The number of cases required to cross the break-even point for MT alone was much higher than the actual number of MT procedures being performed in the 2 hospitals.

Objective: Symptomatic vasospasm (SVS) affects the outcomes of patients with subarachnoid hemorrhage (SAH) and often requires endovascular treatment. Hyponatremia is a predictor of SVS; however, no guidelines have recommended an absolute serum sodium value for SVS prevention. This study aimed to identify factors that influence SVS in patients with low-grade SAH and determine a specific threshold of serum sodium level that predicts SVS.

Methods: We conducted a multicenter, retrospective study of 216 patients with aneurysmal SAH grades I–III (World Federation of Neurological Societies scale). Patients were divided into the endovascular treatment-needed vasospasm (etVS) group (n = 29) and non-etVS group (n = 187). The minimum serum sodium level (minNa) was determined in the initial 2 weeks after SAH onset.

Results: The minNa of the etVS group (median 132 mmol/L) was significantly lower compared to that of the non-etVS group (median 136 mmol/L) (p <0.001). The receiver operating characteristic curve revealed that a threshold minNa of 133 mmol/L predicted the development of etVS (sensitivity 0.797 and specificity 0.552), and the area under the curve was 0.703 (95% confidence interval [CI]: 0.591–0.815). The odds ratios for etVS in patients with a minNa ≤128 mmol/L and 129–132 mmol/L were 6.79 (95% CI: 2.24–20.51) and 2.96 (95% CI: 0.90–9.73), respectively, when compared to those with a minNa 133–136 mmol/L.

Conclusion: Serum sodium levels were a predictor of etVS in patients with low-grade SAH. This is the first study to identify a threshold of serum sodium level for predicting etVS, aiding clinicians in setting a management goal for SVS prevention.

Objective: Thrombectomy is the standard recanalization treatment for acute ischemic stroke (AIS) due to large vessel occlusions (LVO). However, thrombectomy was validated using a few brands of devices. New types of thrombectomy devices have been developed, and assessing their safety and efficacy is essential. This study aimed to evaluate the safety and efficacy of thrombectomy with the Aperio Hybrid stent retriever (Acandis, Pforzheim, Germany) in the treatment of patients with AIS due to anterior circulation LVO.

Methods: This was a multicenter registry of thrombectomy in the treatment of stroke due to anterior circulation LVO. Between January 2022 and January 2024, a total of 128 patients were included.

Results: The mean procedure time was 62 minutes. The rates of the main outcomes were recanalization (extended treatment in cerebral ischemia 2b-3) 102/128 (79.7%), symptomatic intracranial hemorrhage 9/128 (7.0%), good clinical outcome (modified Rankin Scale = 0–2) 67/128 (52.3%), and mortality 24/128 (18.7%) at 3 months.

Conclusion: This study showed that, in a multicenter real-life scenario, the Aperio hybrid stent retriever was safe and effective for thrombectomy of anterior circulation strokes. The outcomes of this study were similar to those of previous large thrombectomy studies.

Objective: The prognosis of patients with subarachnoid hemorrhage (SAH) who also develop cardiopulmonary arrest (CPA) is highly unfavorable, and hence they are often not aggressively treated. Presently, the therapeutic indications and factors that affect the prognosis of patients who experienced CPA remain unclear. Therefore, we analyzed SAH patients who experienced CPA, comparing the characteristics of the patients who survived with those who did not.

Methods: The 36 patients were divided into the survivor group (n = 4) and the dead group (n = 32). The patient’s age, sex, location of the aneurysm, the presence of intracranial hematoma, duration of cardiopulmonary resuscitation (CPR), the presence/absence of bystanders, initial electrocardiogram waveform, recovery of brainstem reflexes with motor response, and administration of vasopressors were compared between the 2 groups.

Results: There were no significant differences in age, sex, location of the aneurysm, and presence of intracranial hematoma between the 2 groups. More than 90% of patients in the dead group had a non-shockable rhythm on the initial electrocardiogram waveform. The duration of CPR in the survivor group tended to be shorter than that in the dead group. Bystander CPR was performed on 14 patients, including all 4 of the survivors. All patients in the survivor group achieved recovery of brainstem reflexes with motor response. In the survivor group, all patients either did not need or only transiently needed the administration of vasopressors after the return of spontaneous circulation (ROSC).

Conclusion: Our analysis suggested the following as favorable prognostic factors in SAH patients with CPA: shockable arrhythmia on the initial electrocardiogram waveform, young age, bystander CPR, a short time from CPA to ROSC, recovery of brainstem reflexes with a motor response, and no or transient use of vasopressors. Our results indicate that aggressive treatment may be indicated in SAH patients with CPA who have stable vitals and show improvements in neurological symptoms.

Objective: There are only a few reports about flow diverter (FD) placement for large thrombosed aneurysms of the middle cerebral artery (MCA). We present a case of FD placement for a recurrent large thrombosed aneurysm of MCA at our hospital.

Case Presentation: A 72-year-old man with transient visual field disturbance underwent craniotomy for a large aneurysm in the left MCA; dome clipping was performed because of severe arteriosclerosis. Over several years, the residual aneurysm gradually increased in size, and despite antiplatelet therapy, the patient experienced repeated cerebral infarctions due to intra-aneurysmal thrombosis. A closer examination revealed that the M2 superior trunk was occluded. Thus, we performed FD placement, without further complications. After 6 months, the aneurysm was confirmed to be occluded with an O’Kelly–Marotta grading scale (OKM grade) of D. There was no enlargement of the thrombus inside the aneurysm, and the patient is currently under follow-up observation.

Conclusion: FD placement may be an option for large thrombosed aneurysms of MCA that are difficult to treat with conventional methods.

Objective: Persistent left superior vena cava (PLSVC) is rare, occurring in approximately 0.3%–0.5% of the population. In endovascular treatment (EVT), the left internal jugular vein (IJV) is approached via the left innominate vein from the superior vena cava; however, the left innominate vein is occasionally absent in patients with PLSVC. Careful consideration is required when performing EVT, particularly transvenous embolization (TVE).

Case Presentation: A 70-year-old female presented with a left cavernous sinus dural arteriovenous fistula. Left external carotid angiography findings showed that multiple feeders from the ascending pharyngeal artery, accessory meningeal artery, middle meningeal artery, and the artery of the foramen rotundum had formed a shunted pouch posterolateral to the left cavernous sinus. We initially planned to perform a TVE via the right femoral vein. However, PLSVC was detected on common carotid artery angiography. Consequently, a TVE via the left IJV and coil embolization were performed, resulting in the disappearance of the shunt. The patient was discharged without neurological deficits. PLSVC is a rarely observed thoracic venous malformation, with few reports concerning its management in cerebrovascular EVT. Contrast-enhanced computed tomography is useful for diagnosis; however, most patients with PLSVC are clinically asymptomatic and this abnormality is typically an incidental finding, remaining challenging to detect during a preoperative examination.

Conclusion: It is essential to consider the possibility of PLSVC and to verify the appropriate access route, including the right atrial level and the venous phase, during preoperative cerebral angiography.

Objective: Endovascular thrombectomy is widely performed for acute ischemic stroke due to proximal intracranial artery occlusion. The femoral artery is often selected for puncture. However, common carotid artery puncture may be considered in more challenging cases. When the internal carotid artery is occluded or obstructed by atherosclerosis, puncturing the distal internal carotid artery becomes necessary. This is rare and was reported in only 2 cases. We report here a case of endovascular thrombectomy using direct puncture of the internal carotid artery.

Case Presentation: A 76-year-old male presented with sudden-onset right upper limb hemiparesis and mild dysarthria. Hospital admittance 1 hour later. Diffusion-weighted imaging (DWI) on head MRI revealed a hyperintense area in the left basal ganglia and corona radiata. MRA showed occlusion of the left internal carotid artery and the M2 segment of the left middle cerebral artery. Intravenous tissue plasminogen activator (tPA) was initiated, and endovascular thrombectomy was attempted. However, navigating the occluded left internal carotid artery was impossible. Symptomatic improvement was observed with tPA therapy causing recanalization of the M2 segment. Thus, further treatment was halted. Two days later, aphasia and complete right hemiparesis developed. MRA revealed no left anterior circulation flow. Under general anesthesia, an incision parallel to the left sternocleidomastoid muscle was made, and a direct puncture of the left internal carotid artery was performed to complete thrombectomy.

Conclusion: In difficult-to-access cases, especially when considering puncturing the cervical vessels, our report suggests that exposing the cervical vessels first can improve the hemostasis and puncture performance.

Objective: Dural arteriovenous fistulas (dAVFs) in the paracavernous sinus of the sphenoid wing often present challenges for transvenous access because of their complex venous drainage patterns. Herein, we report the successful diagnosis and treatment of a greater sphenoid wing dAVF using a percutaneous transvenous approach via the Labbé vein.

Case Presentation: A 48-year-old woman presented with tinnitus and was diagnosed with a greater sphenoid wing dAVF. The dAVF was fed by multiple meningeal arteries from the accessory meningeal artery. Shunted blood drained retrogradely into the superficial middle cerebral vein (SMCV) and bilateral inferior petrosal sinus (IPS) via the cavernous sinus (CS). Although communication was observed between the shunt pouch and the lateral part of the CS, the tortuous and narrow nature of this connection suggests difficulty in accessing the shunt pouch via the IPS. Conversely, the SMCV, which served as the primary outflow pathway, was adequately connected to the vein of Labbé with minimal difficulty, facilitating the passage of the microcatheter. The percutaneous transvenous approach via the Labbé vein successfully reached the SMCV and achieved complete obliteration with selective transvenous embolization (TVE) using coils. The symptoms of the patient improved postoperatively, and the patient was discharged without complications.

Conclusion: Greater sphenoid wing dAVFs often rely on the SMCV as the major drainage route, making venous approaches challenging. The route via the vein of Labbé through the cortical veins to reach the SMCV proved to be a valuable access route for TVE of greater sphenoid wing dAVFs.

Objective: The optimal treatment strategy for large-vessel occlusion (LVO) related to intracranial atherosclerotic disease (ICAD), particularly for tandem lesions that complicate access and device delivery, remains unclear. We report a case in which angioplasty with a stent retriever (SR) and combined antithrombotic therapy was effective in treating re-occlusion associated with dissection of the residual stenosis after thrombectomy for acute atherosclerotic occlusion of the basilar artery (BA) with the left vertebral artery (VA) stenosis.

Case Presentation: An 80-year-old woman was brought to our hospital with progressively worsening consciousness and tetra-paresis. MRA revealed occlusion of the middle to proximal portion of the BA. The patient underwent percutaneous transluminal angioplasty using a balloon catheter for severe stenosis at the origin of the left VA, followed by mechanical thrombectomy for the BA occlusion. While initial recanalization was achieved, residual stenosis in the proximal portion of the BA led to re-occlusion. An attempt at angioplasty with a balloon catheter failed to reach the stenotic segment due to stenosis and tortuosity of the left VA. Consequently, the SR was redeployed into the BA, and a loading dose of antiplatelet agents and intravenous anticoagulant were administered during prolonged deployment. Following the confirmation of BA patency, the SR was re-sheathed and removed. The patient achieved remarkable improvement in consciousness and tetra-paresis without postoperative re-occlusion of the BA.

Conclusion: Angioplasty with a SR and combined antithrombotic therapy may be a useful treatment option for ICAD-related LVO, particularly in cases such as tandem lesions that hinder access and make distal balloon catheter navigation challenging.

Objective: Reversible cerebral vasospasm syndrome (RCVS) is characterized by multiple reversible convulsions of the cerebral arteries, accompanied by recurrent, thunderclap-like headaches. The prognosis of most patients is favorable; however, extensive cerebral infarction may result in significant disability or mortality in approximately 5% of cases. Endovascular treatment may be a therapeutic option for patients who do not respond to medical therapy. However, there is a paucity of detailed studies addressing this procedure.

Case Presentation: A 33-year-old woman presented with severe headache and elevated blood pressure during parturition, resulting in a decreased level of consciousness for 2 days postpartum. Head imaging revealed an intracerebral hemorrhage in the right caudate head nucleus and severe multiple stenoses of the cerebral vessels, leading to a diagnosis of RCVS. Despite treatment with verapamil and magnesium, complete paralysis of both lower limbs, the right upper limb, and aphasia developed on postpartum day 8 (day P8). Nicardipine was injected into the bilateral internal carotid arteries (ICAs) and vertebral arteries, and balloon angioplasty was performed at the tips of the bilateral ICA. Symptoms recurred, and the same nicardipine injection was administered on days P9 and P10. Vasoconstriction gradually improved, no major cerebral infarction occurred, and the patient was able to walk (modified Rankin Scale score, 1) by day P90.

Conclusion: Despite medical treatment, there are cases of extensive cerebral infarction due to strong vasoconstriction, and the postpartum period is a risk factor. Endovascular treatment is an effective option for severe RCVS.

Objective: A ruptured aneurysm rarely causes a primary intraventricular hemorrhage. Cases of aneurysms concomitant with internal carotid artery occlusion are occasionally reported; however, no previous studies have described lateral posterior choroidal artery (LPChA)-associated aneurysms with internal carotid artery occlusion.

Case Presentation: We experienced a case of intraventricular hemorrhage caused by the rupture of an LPChA aneurysm associated with the collateral circulation of internal carotid artery occlusion. After a detailed preoperative imaging study, the embolization was successfully achieved using n-butyl-2-cyanoacrylate without new neurological deficits.

Conclusion: This case highlights the importance of knowledge of the functional anatomy of collateral anastomosis of the intraventricular choroidal arteries, which allowed safe and successful embolization of the aneurysm.

Objective: Two mechanical thrombectomy techniques are proposed for tandem occlusion of the anterior circulation: treating the extracranial carotid artery lesion first via an antegrade approach and treating the intracranial lesion first via a retrograde approach. Previous reports show that the retrograde approach has a shorter reperfusion time and a better prognosis, but re-occlusion of the intracranial lesion after recanalization may occur. We describe a case of tandem occlusion with repeated intracranial occlusions for mechanical thrombectomy using the retrograde approach and discuss possible countermeasures.

Case Presentation: A 94-year-old woman presented with acute cerebral ischemia due to tandem carotid T occlusion of the left internal carotid artery (ICA) and severe stenosis of the cervical carotid artery. Mechanical thrombectomy via a retrograde approach was performed using a stent retriever, resulting in complete recanalization of the anterior circulation through the ICA after 1 pass. The thrombus dispersed distally from the cervical artery and re-occluded the M1 twice, requiring thrombus re-retrieval each time.

Conclusion: The retrograde approach to tandem occlusion can result in repeated re-occlusion after recanalization of the intracranial lesion. Thrombi in cervical carotid lesions are usually fragile. Prior thrombus aspiration from the balloon guiding catheter at the carotid lesion may prevent re-occlusion after recanalization of the intracranial lesion without sacrificing the time advantage of early recanalization via the retrograde approach.

Objective: A right-sided aortic arch is a rare vascular anomaly, and neuroendovascular therapy through the right-sided aortic arch is extremely rare. Herein, we report the case of a patient with a right-sided aortic arch who performed a mechanical thrombectomy for medium-vessel occlusion.

Case Presentation: An 84-year-old woman could not respond to her family during a conversation at 8:50 am. She was brought to our hospital at 10:30 am on the same day. A diffusion-weighted image of head magnetic resonance imaging revealed a high-intensity area in the left temporal lobe. Head magnetic resonance angiography revealed a loss of the inferior trunk of the left middle cerebral artery. A mechanical thrombectomy was performed. The guiding catheter ascended on the right side from the midline, and the patient was considered to have a right-sided aortic arch. Selecting the left common carotid artery was difficult due to its unusual origin from the ascending aorta. Internal carotid angiography revealed left temporo-occipital artery occlusion. Mechanical thrombectomy was performed using Solitaire X 3× 20 mm (Covidien, Irvine, CA, USA), and recanalization was achieved. Contrast-enhanced chest and abdominal computed tomography revealed a right-sided aortic arch with an aberrant left subclavian artery. She was transferred to a recovery hospital with a modified Rankin Scale score of 1.

Conclusion: Understanding the branching patterns and classifications of the right-sided aortic arch is necessary for physicians performing mechanical thrombectomy.

Objective: Duplication of extracranial cerebral arteries is a rare anatomical variant, most commonly observed in the vertebral artery. However, duplication of the cervical internal carotid artery (ICA) is extremely rare. We present a unique case of a patient diagnosed with a right facial artery aneurysm, in whom a right duplicated ICA, ipsilateral persistent stapedial artery (PSA), and contralateral aberrant ICA were incidentally identified.

Case Presentation: A 56-year-old woman presented with a painless mass in the right lower jaw. Physical examination revealed a round, pulsatile mass. Contrast-enhanced CT demonstrated a 25 mm saccular aneurysm originating from the right facial artery, along with a right duplicated ICA and a left aberrant ICA. The lateral limb of the right duplicated ICA and the left aberrant ICA were seen traversing the tympanic cavity and entering the carotid canal. The absence of the right foramen spinosum indicated the presence of a PSA. Angiography confirmed the duplicated ICA, aberrant ICA, and PSA. The lateral limb of the right duplicated ICA gave rise to the occipital artery and a small branch, the PSA, which entered the middle cranial fossa. The facial artery aneurysm was successfully embolized. Follow-up MR angiography showed stable occlusion of the aneurysm, with the duplicated ICA giving off both the PSA from the lateral limb and a pharyngeal branch from the medial limb.

Conclusion: This case provides valuable insights into the development of the cervical arterial system during the fetal period, particularly the collateral pathways connecting the third arch to the dorsal aorta.

Objective: Mechanical thrombectomy (MT) for acute ischemic stroke usually requires blind procedures when endovascular devices are advanced into the occluded vessels. Therefore, the visualization of occluded vessels could potentially achieve safer procedures, shorter procedural time, and progression of the reperfusion rate. We report on the usefulness of a novel technique in which a 3D roadmap of occluded vessels was created from a rapid 3D proton density-weighted (PDW) variable refocusing flip angle and turbo spin echo (VRFA-TSE) method.

Case Presentation: 3D PDW VRFA-TSE imaging was performed in addition to routine MRI for 2 patients with middle cerebral artery occlusion. With the adjustments to the imaging parameters, we were able to perform 3D PDW imaging in less than 1 minute. Subsequently, a 3D image of the occluded vessels was constructed from these images. To create a 3D roadmap, the 3D PDW images were positioned with cone beam CT images obtained before MT using 3D-3D fusion. Because a neurological technician performed the imaging processing while doctors and nurses prepared for MT, practical loss time was approximately 2 minutes. MT was performed with reference to the 3D roadmap, and the occluded lesion was recanalized without complications in both patients. The 3D roadmap of the occluded vessels was well-matched with the recanalized vessels.

Conclusion: A 3D roadmap created from rapid 3D PDW imaging is a useful assistance technique for MT that allows the visualization of occluded vessels.

Objective: The Woven EndoBridge (WEB; MicroVention TERUMO, Tustin, CA, USA) is an intrasaccular flow disruptor developed for the treatment of wide-neck bifurcation aneurysms (WNBA). While its safety and satisfactory mid- to long-term treatment outcomes have been documented, there have also been reports of complications such as WEB protrusion and migration. We encountered 3 cases in which the WEB protruded or migrated to the parent vessel after deployment, necessitating retrieval. In this report, we address the technical tips for retrieval techniques and factors associated with these complications, including a literature review.

Case Presentation: Of the 120 cases of our experience with WEB treatment for cerebral aneurysms for the period since January 2021, 3 required WEB retrievals. In 2 cases, significant WEB migration toward the parent vessel occurred while maneuvering the delivery microcatheter because of sticky detachment. In the remaining case, after detachment of the WEB, tilting occurred, leading to a strong protrusion into one of the branches, which prevented guiding the microcatheter for bailout stenting. In all cases, the proximal marker of the WEB was captured using an Amplatz Goose Neck Microsnare (Medtronic, Minneapolis, MN, USA) pulled back into the VIA catheter (the delivery catheter for the WEB; MicroVention TERUMO), and further into an intermediate catheter positioned as close to the aneurysm as possible, enabling uneventful retrieval.

Conclusion: None of the cases damaged the aneurysm or proximal parent vessel wall, and additional aneurysm occlusion treatment was performed. However, WEB protrusions and migration are rare. When retrieval is required, it is crucial to act swiftly owing to the risk of distal thrombosis from the lumen inside of the WEB. Therefore, recognizing Goose Neck Microsnare as a retrieval technique is valuable.

Objective: This report describes the creation of a freestanding cerebrovascular model with an attached Luer valve device and a bridge.

Case Presentation: A left internal carotid artery aneurysm was discovered during a detailed examination of headaches in a 70-year-old woman. A vascular lumen model was created for the pretreatment simulation. The addition of a male Luer valve and bridge to the vascular lumen model created using the multistep vascular wall thickness method facilitated lumen washing, support material removal, self-support, and compatibility with medical devices.

Conclusion: By adding Luer valves and struts and creating cerebral vascular lumen models with appropriate vessel wall thicknesses, we can enhance their efficiency, strength, and utility in preoperative simulations.

Anterior cranial fossa (ACF) dural arteriovenous fistula (DAVF) is a rare lesion among cerebral DAVFs. This lesion shows significant bleeding risk because of the angioarchitecture, involving direct leptomeningeal retrograde venous drainage, as a nonsinus-type DAVF. Over the years, direct surgery has been considered the primary treatment for ACF DAVF, offering favorable clinical outcomes compared to a low complete obliteration rate with endovascular treatment and the relatively high risk of blindness due to central retinal artery occlusion with transophthalmic artery embolization. In recent years, however, significant improvements in DSA and 3D reconstruction imaging quality have allowed a much more precise understanding of the angioarchitecture of the shunt and vascular access route. In addition, advances in endovascular devices, including catheters and embolic materials, have facilitated microcatheter navigation into more distal vessels and more reliable closure of the fistulous point. Supported by such technological innovations, endovascular approaches to the treatment of ACF DAVF have been becoming successful first-line treatments. This article reviews the evolution of treatment strategies and the current status of endovascular treatment for ACF DAVF, with a particular focus on transarterial embolization.

The sphenoid wing dural arteriovenous fistulas (DAVFs) are clinically rare. They often present as non-sinus-type arteriovenous fistulas (AVFs) and may be associated with focal neurological deficits, intracranial venous hypertension, and intracranial hemorrhage. These cases are classified as lesser or greater sphenoid wing lesions. We searched the PubMed databases for studies evaluating the clinical presentation, surgical treatment, and endovascular treatment of these lesions and analyzed 37 cases from 22 papers. A total of 17 cases had lesser sphenoid wing AVFs, and the localization of the shunts could be divided into the sinus of the lesser sphenoid wing (SLSW) or the superficial middle cerebral vein (SMCV). Most SLSW AVFs drained into the cavernous sinus, but two cases drained directly into the deep middle cerebral vein via a bridging vein. All cases with shunts directly into the SMCV had reflux into the SMCV with varices. A total of 20 cases had shunts in the greater sphenoid wing, and the localization of the shunts varied, with shunt localization, and venous return morphology dependent on variations in middle fossa venous return. Most cases had shunts in the sphenobasal vein near the foramen ovale. However, some cases had shunts in the superior ophthalmic vein, sphenopetrosal vein, and laterocavernous sinus. Many were associated with cortical venous reflux. These lesions have been treated by surgical ligation of the drainage vein and transarterial or transvenous embolization. Recently, embolization has become the standard treatment for DAVFs due to advances in endovascular techniques. This paper reviewed and discussed the angioarchitecture, clinical presentation, and treatment of these lesions to clarify the characteristics of sphenoid wing DAVFs.

Dural arteriovenous fistula (dAVF) of the foramen magnum (FM) region is rare. Moreover, the terminology of dAVF is very confusing in this region. In the narrow sense, the FM dAVF is the non-sinus-type dAVF with direct venous reflux to the medulla oblongata or spinal cord via the bridging veins (BVs) of the FM. Previous literature was systematically reviewed to investigate the clinical characteristics, angioarchitecture, and effective treatment of the FM dAVF. From the literature review, almost all the feeders of FM dAVF were dural branches. Spinal pial arteries were rarely involved as the feeder. All lesions had venous reflux to the medulla oblongata via medullary BVs. The FM dAVF is characterized by a significant male predominance and a high incidence of aggressive symptoms. The most common symptom is congestive myelopathy, followed by hemorrhage. The FM dAVF differs from the craniocervical junction (CCJ) arteriovenous fistula (AVF) and is similar to the thoracolumbar spinal dAVF. Direct surgery for the FM dAVF is effective and safe. Endovascular treatment for the FM dAVF may be more effective and has lower complication rates than that for the CCJ AVF.

The clinical manifestations of dural arteriovenous fistulas (dAVFs) are highly variable and dependent on the hemodynamic properties and location of the fistula. The locations of the fistula are numerous and include the cavernous sinus, transverse–sigmoid sinus, superior sagittal sinus, inferior and superior petrosal sinuses, anterior condylar confluence, tentorium, anterior cranial fossa, middle fossa, foramen magnum, cranio-cervical junction, convexity, and spinal cord. These dAVFs can be divided into two types, “sinus type” and “non-sinus type,” based on their communication with dural shunts and cerebral veins. The sinus type involves direct communication between the arterial dural branch and one dural sinus, sometimes leading to recruitment of cortical veins. On the other hand, the non-sinus type is embedded into the dura, with the drainage always involving a cerebral vein and no communication with any sinus. Treatment options for these types of dAVFs differ; sinus-type dAVFs require normally sinus obliteration and occlusion of recruited veins, while non-sinus-type dAVFs require embolization of the drainage vein. Accurately classifying the type of fistula, sinus type or non-sinus type, is critical for developing a proper treatment plan. This review describes clinical characteristics and treatment of those non-sinus-type dAVFs involving unusual locations with illustrative cases.

Antithrombotic therapy plays a crucial role in secondary prevention following ischemic stroke from the acute phase. Numerous trials, along with a meta-analysis, contributed to establishing aspirin as the primary medication for secondary stroke prevention. According to the Cochrane Database of Systematic Review 2022, initiating antiplatelet therapy with aspirin at a dose of 160 mg to 300 mg daily within 48 hours of stroke onset reduces the risk of death or dependency at the end of follow-up. Other antiplatelet drugs, such as clopidogrel, cilostazol, prasugrel, and intravenous ozagrel sodium, are also available within the Japanese Health Care Insurance System. Two pivotal trials from the 2010s underscored the effectiveness and safety of dual antiplatelet therapy (DAPT) using aspirin and clopidogrel, administered for 21 days to 3 months following acute ischemic stroke or transient ischemic attack. However, the extension of DAPT with aspirin and clopidogrel beyond 3 months may result in substantial bleeding risks. Although prasugrel offers a rapid, potent, and consistent inhibition of platelet aggregation and can be used in place of clopidogrel, there is a lack of substantial real-world clinical data on its use in acute ischemic stroke. It is important to recognize that antiplatelet drugs might not be beneficial and could even increase the risk of hemorrhagic events in cardioembolic stroke. In cases of ischemic stroke with nonvalvular atrial fibrillation, direct oral anticoagulants are the primary choice if applicable. Warfarin continues to be the anticoagulant of choice for secondary stroke prevention in patients with mechanical valve replacements. In patients who have undergone intravenous thrombolysis, antithrombotic therapy is generally delayed for up to 24 hours, although there are no definitive guidelines for the period during and immediately after mechanical thrombectomy. This review provides an overview of the current status of antithrombotic therapy for acute ischemic stroke.

Optimal platelet inhibition is critical in patients with carotid and intracranial artery stenosis undergoing carotid artery stenting (CAS) and intracranial artery stenting (ICS). Many reports have highlighted the importance of dual antiplatelet therapy (DAPT) in reducing adverse neurological outcomes without a significant increase in bleeding complications during CAS. DAPT has commonly used CAS and ICS, typically with aspirin and clopidogrel, but clopidogrel resistance occurs in approximately 20% of Japanese and other Asian populations. One solution to clopidogrel resistance is using adjunctive cilostazol to suppress the frequency of stroke events and in-stent restenosis after CAS. Other antiplatelet agents such as prasugrel, ticagrelor, cangrelor, and glycoprotein (GP) IIb/IIIa inhibitors are under investigation. The duration of DAPT after CAS remains controversial, as a longer duration of DAPT after CAS is associated with lower rates of readmission for stroke, but increased risk of hemorrhagic complications. Regarding antithrombotic therapy in CAS with concomitant atrial fibrillation, the use of direct oral anticoagulants plus a P2Y12 inhibitor may be suggested for the optimal safety and efficacy of antithrombotic management. For emergent CAS in acute ischemic stroke (AIS), intraprocedural DAPT loading and GP IIb/IIIa inhibitors, as necessary, may improve stent patency without increasing the risk of intracranial hemorrhage. In ICS, aggressive antiplatelet therapy based on an assessment of platelet aggregation is also important to improve clinical outcomes. In addition, rescue stenting for AIS caused by intracranial atherosclerotic stenosis-related large vessel occlusion is gaining attention. GP IIb/IIIa inhibitors have shown promise, but are not approved in Japan. In conclusion, DAPT is essential for the perioperative management of CAS and ICS. Specific perioperative antithrombotic management remains unclear, but the potential benefits of antithrombotic agents must be weighed against the corresponding increased risk of bleeding complications.

Thromboembolism is one of the main causes of severe complications in the endovascular treatment of cerebral aneurysms, and antiplatelet therapy (APT) is necessary to prevent such complications. Conversely, prolonged APT has the potential risk of hemorrhagic complications; therefore, the timing of dose reduction or discontinuation is an important aspect of periprocedural APT. However, no clinical evidence of an optimal regimen of APT for cerebral aneurysms exists, and the selection, dosage, duration, or combination of antiplatelets has been dependent on physicians for unruptured or ruptured cerebral aneurysms. Many reports have shown that preoperative APT can reduce ischemic complications without increasing hemorrhagic complications, and some reports have shown that the P2Y12 reaction unit (PRU) value measured using the VerifyNow (Werfen, Barcelona, Spain) system is associated with periprocedural ischemic and hemorrhagic complications. Appropriate dose and duration management adjustments based on the platelet reactivity test, aneurysm morphology, treatment, and patient background may contribute to good outcomes. Although accumulating evidence exists regarding the efficacy of preoperative APT, there is no evidence regarding the optimal duration or discontinuation of APT.

Brain arteriovenous malformations (AVMs) are intricate networks of blood vessels in which arteries connect directly to veins, bypassing the capillary system. This aberration can lead to serious neurological manifestations, including seizures, headaches, and hemorrhagic strokes. The embryonic development of AVMs implicates possible disruptions in arteriovenous differentiation during angiogenesis, improper regression of the primary capillary plexus, or the retention of fetal vasculature as contributing factors. Additionally, genetic mutations and environmental influences during pregnancy may facilitate AVM formation, with identified mutations in genes such as endoglin, activin receptor-like kinase 1, SMAD family member 4, and RAS p21 protein activator 1 disrupting vascular development. Such mutations are associated with conditions like hereditary hemorrhagic telangiectasia and capillary malformation-arteriovenous malformation syndrome, thus highlighting the essential role of genetic counseling in AVM management. This review underscores the importance of a deep comprehension of the embryological and genetic foundations of AVMs to refine diagnostic, therapeutic, and prognostic approaches. The paper advocates for advanced research on intervention strategies and emphasizes the significance of a genetics-focused approach in the clinical management of AVMs.

Brain arteriovenous malformations (bAVMs) are associated with a high risk of intracerebral hemorrhage, which causes severe complications in patients. Although the genetic factors leading to hereditary bAVMs have been extensively investigated, their pathogenesis are still under study. This review examines updated data on the molecular and genetic aspects of bAVMs, the architecture of microvasculature, the roles of angiogenic factors, and signaling pathways. The compiled information may help us understand the pathogenesis of both sporadic and hereditary bAVMs and develop appropriate preemptive treatment approaches.

Objective: The authors aimed for a systematic review to clarify the current role of transarterial embolization (TAE) in the management of brain arteriovenous malformations (BAVMs).

Methods: A search was conducted on PubMed, using the following terms; “brain arteriovenous malformation,” “cerebral arteriovenous malformation,” “endovascular treatment,” and “transarterial embolization.” Studies reporting the efficacy and safety of endovascular treatment for BAVMs, performed either as a standalone treatment or in conjunction with surgery or radiosurgery, were included. The final search was conducted in December 2023. Only articles written in English were reviewed. The references of publications of interest were also screened. Studies on transvenous embolization were excluded. More than 100 articles on the treatment of BAVMs were reviewed.

Results: Advances in endovascular techniques and devices have enabled TAE as a treatment modality for BAVMs, to achieve higher embolization rates. Thus, curative TAE for some BAVMs with suitable angioarchitecture has become possible. The efficacy of presurgical TAE in the treatment of low Spetzler-Martin grade BAVMs is limited; however, TAE is effective for intermediate grade BAVMs. Several reports using propensity-matched analyses reevaluated the therapeutic efficacy of pre-/post-radiosurgical TAE for BAVMs with radiosurgery-resistant lesions such as large nidus, fistulous components, and associated aneurysms. The complication rate of TAEs as a treatment modality for BAVMs is approximately 10%, and hemorrhagic complications occur in approximately 5% of cases. Despite recent advances, substantial improvements have not been observed in the morbidity and mortality associated with TAEs for the treatment of BAVMs.

Conclusion: TAE for the treatment of BAVMs is primarily performed in an adjuvant manner; however, recent advances have made standalone embolization possible. A multidisciplinary team should evaluate each case independently. Furthermore, as per recent studies, inclusive of meta-analyses, the efficacy and safety of TAEs for the treatment of BAVMs have not been elucidated. Thus, the manifestations and characteristics of BAVMs, in addition to the objective of performing a TAE, should be deliberated carefully before the endovascular procedure, to avoid complications.

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.

Onyx (Medtronic, Minneapolis, MN, USA) is a non-adhesive liquid embolic agent composed of an ethylene vinyl alcohol (EVOH) copolymer dissolved in dimethyl sulfoxide (DMSO). Onyx is explicitly designed for use in interventional neuroradiological procedures. Onyx’s unique formulation allows controlled delivery and solidification within the target vessel, providing durable occlusion of abnormal vascular structures such as arteriovenous malformations and dural arteriovenous fistulas. This report reviews the basic understanding of the use of Onyx in interventional neuroradiology. The hydrophilic properties of the agent facilitate its smooth delivery through microcatheters, ensuring precise navigation and deposition within vascular malformations under fluoroscopic guidance. When Onyx was injected into the target vessel, the vessel was embolized as the solvent (DMSO) diffused into the blood and EVOH precipitated to form a durable cast. Onyx liquid embolic agents substantially advance the endovascular treatment of intracranial vascular lesions.

Various types of embolic substances are used in endovascular therapy, and understanding their characteristics, including shape and kinetics, is essential for proper use. Cyanoacrylate is a typical liquid embolization agent that can be applied to many cerebral neurovascular lesions. It is injected as a mixture with ethiodized oil to provide radiopacity and regulate the polymerization rate. This review describes the characteristics, action mechanisms, techniques of use, and potential pitfalls of using cyanoacrylate-ethiodized oil mixtures for embolization.

This review discusses the use of N-butyl cyanoacrylate (NBCA) in various neuroendovascular treatments. Despite the increase in the ONYX, NBCA continues to have significant usage. It is particularly useful for the treatment of arteriovenous malformations (AVM) and dural arteriovenous fistulas (dAVFs). Comparative studies have suggested that ONYX and NBCA are equally effective and safe for the treatment of AVM. However, the choice between the two depends on specific situations, such as the characteristics of the feeding arteries. NBCA is recommended for tortuous feeders, high-flow fistulous feeders, and feeders with a short margin of reflux, owing to the procedural risks posed by ONYX. The use of NBCA is also prominent in dAVF embolization. While achieving total occlusion solely with NBCA can be challenging, NBCA adheres to the vessel wall and encourages thrombus formation, aiding in fistula obliteration. In addition to AVM and dAVF, NBCA is used to treat chronic subdural hematoma and craniofacial vascular injuries. Embolization using NBCA is beneficial because of its deep penetration into the target tissue. For craniofacial injuries, NBCA embolization provides secure hemostasis within a short time. Neuroendovascular physicians should understand the characteristics of NBCA as a liquid embolic material and have expertise in the technical aspects of NBCA embolization, even in the ONYX era.