Endovascular treatment of the cavernous sinus dural arteriovenous fistula: current status and considerations

Transarterial embolization in non-cavernous and cavernous sinus dural arteriovenous fistulas: A systematic review and meta-analysis of proportions

BACKGROUND

Transarterial embolization (TAE) is pivotal in managing non-cavernous and cavernous sinus dural arteriovenous fistulas (CSDAVFs).

METHODS

Systematic searches were conducted across ScienceDirect, Medline, and Cochrane databases for longitudinal studies on TAE outcomes in non-CSDAVFs and CSDAVFs. Post-procedural outcomes, including complete, incomplete, and failed AVFs obliteration, and end-study outcomes were analyzed.

RESULTS

Our meta-analysis involved 27 studies with 643 patients and 736 fistulas. Symptoms in both groups included tinnitus (29.74 %), ocular/visual symptoms (29.12 %), hemorrhage (19.42 %), and headache (19.11 %). Feeding arteries mainly originated from the meningeal arteries (49.16 %). In non-CSDAVFs cases, fistula locations were within sinus complexes (69.23 %) and specific dural areas (28.31 %). Complete AVFs obliteration was 81 % (95 %CI: 70 % - 90 %), slightly higher in non-CSDAVFs (82 %, 95 % CI: 69 % - 92 %) than CSDAVFs (79 %, 95 %CI: 58 % - 95 %). Incomplete obliteration occurred in 14 % (95 %CI: 5 % - 39 %), with rates of 11 % (95 %CI: 2 % - 26 %) in non-CSDAVFs and 19 % (95 % CI: 5 % - 39 %) in CSDAVFs. Failed obliteration was rare (1 %, 95 %CI: 0 % - 3 %), with similar rates in both groups. At end-study follow-up, resolution of AVFs was achieved in 97 % of cases (95 %CI: 92 % - 100 %). However, complications occurred in 17 % of cases (95 %CI: 10 % - 25 %), with a higher incidence in CSDAVFs (22 %, 95 %CI: 9 % - 37 %) compared to non-CSDAVFs (13 %, 95 %CI: 6 % - 23 %).

CONCLUSIONS

TAE with embolic agents demonstrates favorable outcomes in non-CSDAVFs and CSDAVFs, with high rates of AVFs obliteration and resolution. Complications, particularly in CSDAVFs, warrant careful consideration in treatment decisions.

Proposal of a Classification System of Cavernous Sinus Dural Arteriovenous Fistulas and Treatment Strategies Based on Angioarchitecture: A Cohort Study of 116 Patients

BACKGROUND

Cavernous sinus (CS) dural arteriovenous fistulas (DAVFs) are commonly treated by transvenous embolization, but the details of treatment need to be more clearly defined. We propose a classification of CS-DAVF that can contribute to formulating endovascular treatment process.

METHODS

CS-DAVF was classified into seven categories based on the cumulative CS range and drainage patterns. CS-DAVF angioarchitecture, clinical characteristics, treatment strategies, and outcomes of CS-DAVF patients treated in our hospital from 2012 to 2021 were summarized and analyzed.

RESULTS

Among the 116 patients with CS-DAVF: Type 1, 71 (61.2%); Type 2, 9 (7.8%); Type 3, 18 (15.5%); Type 4, 2 (1.7%); Type 5, 8 (6.9%); Type 6, 3 (2.6%); and Type 7, 5 (4.3%). Inter-CS or inferior petrosal sinus drainage was relatively rare in Types 1 and 6 (P < 0.001 and P < 0.001); basilar venous plexus drainage was more prevalent in Types 2, 5, and 7(P = 0.019). Inferior petrosal sinus occlusion was more commonly seen in Types 2, 3, and 5 (P = 0.005). The most frequent first symptoms and symptoms at admission in patients with CS-DAVF is ocular/orbital symptoms, occurring in 64 cases (55.2%) and 104 cases (89.7%), respectively. In this study, 108 patients (93.1%) underwent endovascular embolization. Among those who received endovascular embolization, 96 (88.9%) CS-DAVFs were treated via transvenous embolization. In long-term follow-up, 98 cases (84.5%) achieved cure, and 17 cases (14.7%) showed symptomatic improvement.

CONCLUSION

Our proposed classification system based on cumulative CS range and drainage patterns can assist in formulating treatment strategies for transvenous embolization.

Clinical Outcomes of Arteriovenous Fistula Treatment Using the Penumbra SMART COIL System: A Subgroup Analysis from the Multicenter SMART Registry

BACKGROUND

Endovascular embolization procedures are typically the primary treatment modality for arteriovenous fistula (AVF). The objective of this subset analysis was to evaluate the prospective long-term clinical outcomes of AVF patients treated with the SMART COIL System.

METHODS

Patients who had AVFs and underwent endovascular coiling using the Penumbra SMART COIL system were part of a subset analysis within the SMART registry. The SMART registry is a postmarket registry that is prospective, multicenter, and single-arm in design. After the treatment, these patients were monitored for a period of 12 ± 6 months.

RESULTS

A total of 41 patients were included. No patients (0/41) had a procedural device-related serious adverse event (SAE). Reaccess involving a guidewire due to catheter kickout was unnecessary for 85.4% (35/41) of the patients. Complete occlusion after the procedure was achieved in 87.8% (36/41) of patients. The periprocedural SAE rate was 2.4% (1/41), and no periprocedural deaths occurred (0/41). During the follow-up period, there were instances of retreatment in 3.4% (1/29) of patients. At 1 year, the lesion occlusion was better or stable in 93.3% (28/30) of patients. The rate of SAE from 24 hours to 1 year (±6 months) following the procedure was 26.8% (11/41). The 1-year all-cause mortality rate stood at 2.4% (1/41), and at the 1-year follow-up, 90.9% (20/22) of patients had a modified Rankin Scale score within the range of 0 to 2.

CONCLUSIONS

The coiling procedure for AVFs using the SMART COIL System proved to be safe and effective at the 1-year follow-up.

Clinical features, treatment, and outcomes of cavernous sinus dural arteriovenous fistulas: a cohort study of 141 patients

PURPOSE

The cavernous sinus (CS) region is a common region of dural arteriovenous fistula (DAVF). Over time, treatment strategies are gradually changing. In this study, we present our center's experience in managing CS-DAVF over the past 20 years.

METHODS

Medical records of patients diagnosed with CS-DAVF between 2002 and 2021 were collected for analysis. Patients meeting the predefined inclusion and exclusion criteria were included. This study summarized and analyzed their clinical characteristics, CS-DAVF angioarchitecture, treatment strategies, and outcomes.

RESULTS

A total of 141 patients (mean age 55 years, 46 males) were included in this study. Ocular/orbital symptoms were the most frequently reported initial symptoms, with 84 (59.6%) patients experiencing these symptoms first. Presentation with ocular/orbital symptoms as the first symptom was associated with thrombosis of the inferior petrosal sinus (p = 0.032). Presentation with headache/dizziness and tinnitus/intracranial murmur as the first symptom was associated with sphenoparietal sinus/superficial middle cerebral vein drainage (p = 0.011). Among the patients, 131 (92.9%) patients received endovascular treatment, with 114 (87.0%) undergoing transvenous embolization. Onyx (92.4%) and coil (74.8%) were the most used embolic materials. 17 (13.0%) of the patients who received endovascular treatment suffered intraoperative or postoperative complications, and 11 (64.7%) patients fully recovered within 6 months after discharge.

CONCLUSION

Ocular/orbital symptoms were the most common first symptom of CS-DAVF. The mode of venous drainage played a significant role in determining the first symptoms. Transvenous embolization using Onyx or a combination of Onyx and coils was the primary treatment modality.

Blood flow alterations in cavernous sinus dural arteriovenous fistula: Optical coherence tomography angiography findings

Purpose

This case report details the diagnostic process for a patient with an initial diagnosis of scleritis who was unresponsive to typical treatment modalities, culminating in the identification of a cavernous sinus dural arteriovenous fistula (CS-DAVF). The case highlights the role of anterior segment optical coherence tomography angiography (OCTA) in the diagnosis of this vascular anomaly and in monitoring the response to treatment.

Observations

A 45-year-old man with persistently elevated intraocular pressure (IOP) and ocular congestion in the left eye was unresponsive to treatment for scleritis. The persistent ocular symptoms and new-onset tinnitus prompted further investigation. Anterior segment OCTA revealed vascular anomalies, and magnetic resonance imaging confirmed a CS-DAVF. The patient underwent endovascular treatment for the CS-DAVF. This intervention led to a significant reduction in IOP in the left eye and the resolution of ocular congestion.

Conclusions and importance

This case highlights the diagnostic complexities of ophthalmic symptoms that mimic those of other conditions. Furthermore, it demonstrates the essential role of anterior segment OCTA in the accurate diagnosis and effective management of CS-DAVF and highlights the need for comprehensive diagnostic approaches in ophthalmology.

And those who were seen dancing: Human interactions with fungi and vice versa

This issue of the Biomedical Journal features a special section exploring mycobiota. Three articles examine the role of fungi in common metabolic disorders in, Clostridium difficile infection, and in immunocompromised patients. Additionally, the potential and challenges of the metaverse in healthcare are reviewed, alongside a holistic approach to improve patient outcomes in pancreatic cancer. In this issue also possible mechanism contributing to long COVID are discussed, as well as biomarkers that effectively predict sepsis outcomes, and key targets in osteosarcoma progression. Moreover, factors leading to peri-intubation cardiac arrest are analyzed, healthcare strategies from various regions are employed to predict cardiovascular events in Asian populations, two approaches to cavernous sinus dural arteriovenous fistula are compared, and a combination therapy against soft tissue sarcoma is presented.

Facilitated Retrograde Access via the Facial Vein for Transvenous Embolization of the Cavernous Sinus Dural Arteriovenous Fistula with Isolated Ophthalmic Venous Drainage

Management of cavernous sinus dural arteriovenous fistula (CSDAVF) continues to present significant challenges, particularly when the inferior petrosal sinus is thrombosed, collapsed, or angiographically invisible. In this study, we introduce facilitated retrograde access via the facial vein, which is employed in the transvenous embolization of CSDAVF with isolated superior ophthalmic venous drainage. We also present illustrative cases and technical points.

Cavernous sinus dural arteriovenous fistula treated with transvenous embolization through facial vein: A case report

BACKGROUND

Although the inferior petrosal sinus (IPS) is the most common approach route for transvenous embolization (TVE) of cavernous sinus dural arteriovenous fistulas (CSDAVFs), other routes should be chosen in cases which the IPS is occluded. We report a case in which the superior ophthalmic vein (SOV) approach through the facial vein (FV) was the first choice to achieve radical cure of a hemorrhage-onset CSDAVF.

CASE DESCRIPTION

An 81-year-old female presented with a history of transarterial embolization (TAE) and TVE for the left CSDAVF 27 years ago. She was transported to us with a chief complaint of consciousness disturbance, and head computed tomography (CT) showed subcortical hemorrhage in the right frontal lobe. Cerebral angiography revealed CSDAVF with draining into the right SOV and right superficial middle cerebral vein (SMCV). Angiography, computed tomography venography, and contrast-enhanced magnetic resonance imaging did not show IPS, but the outflow pathways to the SOV, FV, and internal jugular vein were confirmed, so an approach through the FV was selected.

CONCLUSION

The FV was selected through the right femoral vein and thanks to the distal access catheter (DAC) being guided to the SOV, the microcatheter could be easily guided to the SMCV through the cavernous sinus (CS). TVE was performed, complete occlusion was confirmed. When preoperative occlusion of the IPS was confirmed, the FV was useful for the first choice of route, and the use of DAC allowed us to complete the treatment accurately and quickly.

Management of carotid cavernous fistulas: A single center experience

Purpose

Multimodal endovascular therapy (EVT) of carotid cavernous fistula (CCF) with different approaches and a variety of available embolization material enable high occlusion rates with good clinical and functional outcome but until now there is still little evidence available. This retrospective single-center study aims to evaluate EVT of CCF with different neuroendovascular techniques regarding occlusion rates, complications and outcomes.

Materials and methods

From 2001 to 2021 59 patients with CCF were treated at our tertiary university hospital. Patient records and all imaging data including angiograms were reviewed for demographic and epidemiological data, symptoms, fistula type, number of EVTs, complications of EVT, type of embolic materials, occlusion rates and recurrences.

Results

Etiology of the CCF were spontaneous (41/59, 69.5%) post-traumatic (13/59, 22%) and ruptured cavernous aneurysms (5/59, 8.5%). Endovascular therapy was completed in one session in 74.6% (44/59). Transvenous access was most frequent (55.9% 33/59) followed by transarterial catheterization in 33.9% (20/59) and a combination of both (6/59, 10.2%). Exclusively coils were used in 45.8% (27/59), a combination of ethylene vinyl alcohol (EVOH) copolymer (Onyx) and coils in 42.4% (25/59). Complete obliteration was achieved in 96.6% of patients (57/59) with an intraprocedural-related complication rate of 5.1% (3/59) and no mortality.

Conclusion

Endovascular therapy of CCF has been shown to be safe and effective with high cure rates and low rates of intraprocedural complications and morbidity even in complex scenarios.

Analysis of Etiology, Diagnosis, and Treatment Strategy and Efficacy of Pulsatile Tinnitus Caused by Abnormal Vascular Anatomy

OBJECTIVE

To investigate the etiology, clinical characteristics, diagnosis, and treatment strategies and efficacy of pulsatile tinnitus (PT) caused by vascular anatomy abnormality.

METHODS

The clinical data of 45 patients with PT in our hospital from 2012 to 2019 were collected and retrospectively analyzed.

RESULTS

All 45 patients had vascular anatomical abnormalities. The patients were divided into 10 categories according to the different locations of vascular abnormalities: sigmoid sinus diverticulum (SSD), sigmoid sinus wall dehiscence (SSWD), SSWD with high jugular bulb, pure dilated mastoid emissary vein, aberrant internal carotid artery (ICA) in the middle ear, transverse-sigmoid sinus (TSS) transition stenosis, TSS transition stenosis with SSD, persistent occipital sinus stenosis, petrous segment stenosis of ICA, and dural arteriovenous fistula. All patients complained of PT synchronous with heartbeat rhythm. Endovascular interventional therapy and extravascular open surgery were used according to the location of the vascular lesions. Tinnitus disappeared in 41 patients, was significantly relieved in 3 patients, and was unchanged in 1 patient postoperatively. Except for one patient with transient headache postoperatively, no obvious complications occurred.

CONCLUSION

PT caused by vascular anatomy abnormalities can be identified by detailed medical history and physical and imaging examination. PT can be relieved or even completely alleviated after appropriate surgical treatments.

Transfemoral trans-facial vein-superior ophthalmic vein to embolize cavernous sinus dural arteriovenous fistulas

Cavernous sinus dural arteriovenous fistula (CS-DAVF) is an abnormal communication between the CS and dural arteries from the internal carotid artery and external carotid artery. CS-DAVFs are not uncommon. The preferred treatment for most CS-DAVFs is transvenous embolization (TVE), which can achieve a high cure rate with few complications. The trans-inferior petrous sinus (IPS) route from the internal jugular vein to the CS is the favorite and most direct route to perform TVE in the great majority of CS-DAVFs. However, when the trans-IPS route fails and if the facial vein (FV) is patent and dilated, transfemoral trans-FV-superior ophthalmic vein (SOV) embolization of the CS-DAVF can be attempted. However, the transfemoral trans-FV-SOV route to embolize CS-DAVFs is often challenging, and there is insufficient knowledge about it. Therefore, an updated review of the transfemoral trans-FV-SOV route to embolize CS-DAVFs is necessary, and this review includes our experience. The images in this review are from our institute without the dispute of copyright. Issues regarding the transfemoral trans-FV-SOV route to embolize CS-DAV were discussed, including the FV anatomy and variation, various TVE routes to access CS-DAVF, the procedure of the transfemoral trans-FV-SOV route to embolize CS-DAVF, difficulty, and solution of the transfemoral trans-FV-SOV route to embolize CS-DAVF, and complications and prognosis of transfemoral trans-FV-SOV to embolize CS-DAVF. By reviewing the transfemoral trans-FV-SOV route to embolize CS-DAVFs, we found that this route provides a valuable alternative to the other transvenous routes. A good prognosis can be obtained with the transfemoral trans-FV-SOV route to embolize CS-DAVFs in select cases.

Usefulness of a Curved Multiple Reconstruction Image for Transarterial Intravenous Coil Embolization of a Dural Arteriovenous Fistula of the Sphenobasal Vein: A Case Report

Hemorrhagic isolated dural arteriovenous fistulas (DAVFs) are often challenging to treat. Here, we report a case of the lateral cavernous sinus (CS) DAVF successfully treated by transarterial intravenous coil embolization using a curved multiplanar reconstruction (MPR) image assistance. A 54-year-old man presented with a severe headache and was diagnosed with subarachnoid hemorrhage caused by CSDAVF. Angiography indicated that the fistula was fed by branches of the left external carotid artery and drained into cortical veins. There were multiple shunting points at the left sphenobasal vein accompanied by varicose veins. Using curved MPR images, the left accessory meningeal artery was chosen for the endovascular approach into the affected veins, including ruptured varix. The shunt was completely occluded by detachable coils.

When the curved MPR image indicates a developing feeding artery and a large shunting point, transarterial intravenous coil embolization becomes a good treatment option for CSDAVF, which has no venous access.

Use of a Rigid-Tipped Microguidewire for the Endovascular Treatment of Cavernous Sinus Dural Arteriovenous Fistulas with an Occluded Inferior Petrosal Sinus

OBJECTIVE

Transvenous embolization (TVE) via an occluded inferior petrosal sinus (IPS) in a cavernous sinus dural arteriovenous fistula (CSDAVF) is challenging, often requiring navigation of a microcatheter through resistive obstacles between the occluded IPS and shunted pouch (SP), although the reopening technique was successfully performed. We report five cases of successful access to the cavernous sinus (CS) or SP using the rigid-tipped microguidewire such as chronic total occlusion (CTO) wire aiming to share our initial experience with this wire.

METHODS

In this retrospective study, four patients with CSDAVF underwent five procedures using the CTO wire puncture during transfemoral transvenous coil embolization. Puncture success, shunt occlusion, and complications including any hemorrhage and cranial nerve palsy were evaluated.

RESULTS

Despite successful access through the occluded IPS, further entry into the target area using neurointerventional devices was impossible due to a short-segment stricture before the CS (three cases) and a membranous barrier within the CS (two cases). However, puncturing these structures using the rigid-tipped microguidewire was successful in all cases. We could advance the microcatheter over the rigid-tipped microguidewire for the navigation to the SP and achieved complete occlusion of the SP without complications.

CONCLUSION

The use of the rigid-tipped microguidewire in the TVE via the occluded IPS of the CSDAVF would be feasible and safe.

Serous retinal detachment secondary to an unsuccessful transarterial embolization in a post-traumatic carotid-cavernous sinus fistula patient: A case report

A carotid-cavernous sinus fistula (CCF) is an abnormal communication between the cavernous sinus and the carotid arterial system. Direct CCFs arise from a direct connection between the cavernous sinus and the cavernous portion of the internal carotid artery. Nowadays, endovascular neurosurgery has become the first-line treatment modality for direct CCFs owing to the high complete obliteration rate. However, reversal of the clinical symptoms may not always be congruous after the endovascular intervention. Herein, we present a 50-year-old patient who manifested diplopia, ophthalmoplegia, and orbital congestion after a traffic accident. He had suffered head injury with right side frontal intracranial hemorrhage 1 month before the ophthalmic presentation. He came to our department primarily because of declining vision and for the above symptoms, and was diagnosed with direct type CCF, for which he received transarterial coil embolization. Unexpectedly, he later presented with serous retinal detachment accompanied by ocular ischemic syndrome secondary to recurrent CCF 1 month after the intervention, so repeat coil embolization was performed.

UPDATE ON MANAGEMENT OF DURAL ARTERIOVENOUS FISTULAS

Dural Arteriovenous Fistulas (AVF) represent about 10% of all intracranial vascular lesions. Although they seem benign in nature, the presence of retrograde venous makes them aggressive, with a high risk of complications. Patients may be clinically asymptomatic or experience symptoms ranging from mild to severe hemorrhage, depending on their location. Different treatments are available, but recently, the development of catheter intervention allows most patients to be cured with transcatheter embolization. Stereotactic radiosurgery achieves excellent rates of obliteration for low-grade lesions. In this review, we try to highlight the recent advances in the management of dural AVF.

Brain arteriovenous malformations and dural arteriovenous fistulas with extensive venous congestive encephalopathy

In brain arteriovenous malformations (BAVMs) and dural arteriovenous fistulas (DAVFs), when too much blood is drained into the venous system, extensive venous congestive encephalopathy (EVCE) can appear. EVCE in BAVMs and DAVFs can be divided into acute and chronic stages. BAVMs and DAVFs have their own classification systems, but EVCE is not considered in these classification systems and needs to be emphasized. EVCE in BAVMs and DAVFs has unique clinical and imaging features. The clinical presentations usually consist of headache, cognitive impairment, and focal deficits. EVCE in BAVMs and DAVFs has several imaging features, and the venous congestion seen on computed tomography angiography and magnetic resonance angiography can present with the angiographic features of venous reflux and pseudophlebitic pattern. Digital subtraction angiography is the gold standard for the diagnosis. Delayed circulation time is observed. Tortuous, dilated, and engorged veins can be seen. For EVCE from BAVMs and DAVFs, prompt treatment is warranted due to the impairment of extensive brain tissue. Treatments include endovascular treatment (EVT), open surgery, and radiosurgery. EVT is often the primary treatment. Complete elimination in one stage is often difficult. Most of the time, staged treatment has to be chosen. No matter at the acute or chronic stage, aggressive treatment is recommended.

Dural carotid-cavernous fistulas: our experience with endovascular management

Background

Indirect carotid-cavernous fistulas (CCF) are dural arteriovenous fistula of the cavernous sinus and generally present with ocular symptoms. High index of clinical suspicion and radiological work up is required for diagnosis, and treatment is primarily endovascular embolization. We present our experience in diagnosis and management of indirect CCF along with technical evolution to perform embolization and different vascular accesses for difficult anatomy.

Results

Among a total of 20 indirect CCF cases who were treated with embolization in our department from 2013 to 2020, five (25%) were type C and 15 (75%) were type D. Seven were treated with trans-arterial access only, 11 were treated by transvenous access only, and two were treated by taking both transvenous and trans-arterial access. No recurrence was seen in angiographically cured patients. Out of seven patients who suffered various grades of visual deficit, five recovered completely and two had fixed visual deficit. Third and sixth cranial nerve palsy persisted in two patients even after CCF embolization.

Conclusion

Indirect CCF is a treatable cause of troublesome ocular symptoms. Endovascular embolization is preferred treatment with excellent short- and long-term outcome. The embolization becomes difficult and challenging in cases where the conventional vascular access to the cavernous sinus is occluded.

Bilateral cavernous sinus dural arteriovenous fistula with initial ocular symptom: A case report

RATIONALE

Cavernous sinus dural arteriovenous fistula (CSDAVF) is a rare intracranial vascular malformation. Because of its complicated clinical manifestations, it is easy to miss or misdiagnose CSDAVF.

PATIENT CONCERNS

A 42-year-old female had chief complaint that the right eyeball had conjunctival congestion for half a year. She was given levofloxacin eye drops to treat the right eye with anti-inflammatory treatment, but the symptoms did not improve. Cranial magnetic resonance and cerebrovascular imaging showed that the right lateral rectus muscle was slightly enlarged, the right eyeball was prominent, but there was no abnormality in the brain.

DIAGNOSES

Based on clinical and imaging examinations and digital subtraction angiography (DSA), she was diagnosed as low-flow CSDAVF.

INTERVENTIONS

The patient received interventional embolization with transvenous combined arterial approach using coils and Onyx liquid glue.

OUTCOMES

The patient's exophthalmos and congestion symptoms were improved.

CONCLUSION

DAS is the gold standard for the diagnose of CSDAVF. Intravascular embolization interventional therapy is an effective treatment for CSDAVF.

Is the Middle Meningeal Artery the Optimal Path for Dural Arteriovenous Fistula Embolization?

Background: The middle meningeal artery (MMA) is the optimal arterial path for endovascular treatment (EVT) of dural arteriovenous fistulas (DAVFs). However, the details are not completely understood.

Materials and Methods: We performed a retrospective study of patients who were admitted to the First Hospital of Jilin University with a diagnosis of cranial DAVF with involvement of the MMA as a feeding artery. On the basis of the arterial path chosen and the role of the MMA in the first EVT procedure, EVT was divided into three types (I–III), each of which was further divided into two subclasses (a and b). The degree of embolization was analyzed.

Result: The 104 included patients ranged in age from 13 to 80 years (mean, 53.6 ± 11.8 years). There were 48 cases of hemorrhage (46.2%, 48/104). Complete embolization was achieved in the first procedure in 64.4% of cases, and success was eventually achieved using EVT (the first attempt or a subsequent attempt) in 74.1% of cases. EVT caused complications in 6.7% of cases. A modified Rankin scale score of 0 or 1 was achieved in 78.8% of patients. Statistical analyses revealed that type Ia and IIb EVTs had the lowest complete embolization rates, but no difference was found between type Ia and IIb EVTs. Types IIa and III EVT had the highest complete embolization rates. Most cases had a good prognosis.

Conclusion: These findings elucidate the features of the different EVT classes defined by the first EVT procedure and the role of the MMA. The delivery of treatment via slim and tortuous MMA branches increased the failure rate of EVT. A thick, straight MMA branch is the optimal path for treatment.