Higher Obliteration Rate Research Articles

Arteriovenous malformations in the cerebellopontine angle: assessment of the "backdoor resection" technique and microsurgical results in 38 patients.

Posterior fossa arteriovenous malformations (AVMs) represent 7% to 15% of all intracranial AVMs and are associated with an increased risk of hemorrhage, morbidity, and mortality compared with supratentorial AVMs, thus prompting urgent and definitive treatment. Cerebellopontine angle (CPA) AVMs are a unique group of posterior fossa AVMs incorporating characteristics of brainstem and cerebellar lesions, which are particularly amenable to microsurgical resection. This study reports the clinical, radiological, operative, and outcome features of patients with CPA AVMs in a large cohort. The authors conducted a single-surgeon, 2-institution retrospective cohort study of all consecutive patients with CPA AVMs treated with microsurgical resection during a 25-year period. CPA AVMs represented 22% (38 of 176) of all infratentorial AVMs resected by the senior author. Overall, 38 patients (22 [58%] male and 16 [42%] female) met the study inclusion criteria and were analyzed. Most patients presented with hemorrhage (n = 29, 76%). The median age at surgery was 56 (range 6-82) years. Subtypes included 22 (58%) petrosal cerebellar AVMs, 11 (29%) lateral pontine AVMs, and 5 (13%) AVMs involving both the brainstem and cerebellum. Most AVM niduses were small (< 3 cm; n = 35, 92%) and compact (n = 31, 82%). Fourteen (37%) patients harbored flow-related aneurysms. Twenty (53%) patients underwent preoperative embolization. Complete angiographic obliteration was achieved with microsurgery in 35 (92%) patients. Five (13%) patients with poor neurological conditions at presentation died before hospital discharge. Of the 7 (18%) patients with new postoperative neurological deficits, 5 had transient deficits. The median (interquartile range) follow-up was 1.7 (0.5-3.2) years; 32 (84%) patients were alive at last follow-up, and 30 (79%) had achieved a favorable neurological outcome (modified Rankin Scale [mRS] score 0-2). The only independent predictor of unfavorable postoperative outcome (mRS score 3-6) was the preoperative mRS score (p = 0.002). CPA AVMs are unique posterior fossa lesions, including petrosal cerebellar and lateral pontine AVMs. The "backdoor resection" technique provides a safe and efficient strategy with high obliteration rates and a low risk of treatment-related morbidity. Microsurgical resection should be considered the frontline treatment for most CPA AVMs, except for those with a significant diffuse brainstem component.

Safety evaluation of sinus patency after stereotactic radiosurgery for transverse-sigmoid sinus dural arteriovenous fistulas: implications of treatment options for patients with Borden type I fistulas.

This study aimed to assess the efficacy and safety of stereotactic radiosurgery (SRS) in treating transverse-sigmoid sinus dural arteriovenous fistulas (TSS DAVFs), and to investigate post-SRS sinus patency, focusing on the risk factors associated with treated sinus occlusion. Data from 34 patients treated with SRS between January 2006 and April 2023 were analyzed. Detailed angioarchitecture was confirmed using digital subtraction angiography before SRS. Angiography of the ipsilateral internal carotid artery and vertebral artery was performed to evaluate whether the involved side of the TSS was used for normal venous drainage. TSS stenosis was defined as sinus diameter < 50% of the normal proximal diameter. DAVF shunt obliteration, TSS occlusion, neurological status, and adverse events were also evaluated. Of the 34 patients, 21 had Borden type I and 14 had Borden type II DAVFs. The median age at SRS was 64 years (interquartile range 54-71 years), and the follow-up period was 31 months (interquartile range 15-94 months). Complete shunt obliteration was achieved in 24 (70.6%) patients. The cumulative 2-, 3-, and 5-year shunt obliteration rates were 49.6%, 71.2%, and 86.0%, respectively. Borden type I had higher obliteration rates (60.5%, 83.1%, and 94.4%, respectively) than Borden type II (41.7%, 51.4%, and 75.7%, respectively; p = 0.034). TSS occlusion occurred in 5 patients (14.7%). The cumulative 1-, 5-, and 10-year TSS occlusion rates were 2.9%, 8.3%, and 23.6%, respectively, across the entire cohort. All occlusions occurred exclusively in the sinuses that were not used for normal venous drainage. Cox proportional analyses revealed that TSS stenosis and the sinus not being used for normal venous drainage were significantly associated with a greater risk of TSS occlusion after SRS (HR 9.44, 95% CI 1.01-77.13; p = 0.049). SRS is effective and safe for TSS DAVF and results in favorable shunt obliteration, symptom improvement, and low complication rates. TSS occlusion after SRS is asymptomatic and is limited to sinuses that are not used for normal venous drainage.

Diagnostic and therapeutic role of endoscopic ultrasound in liver diseases: A systematic review and meta-analysis.

In hepatology, the clinical use of endoscopic ultrasound (EUS) has experienced a notable increase in recent times. These applications range from the diagnosis to the treatment of various liver diseases. Therefore, this systematic review summarizes the evidence for the diagnostic and therapeutic roles of EUS in liver diseases. To examine and summarize the current available evidence of the possible roles of the EUS in making a suitable diagnosis in liver diseases as well as the therapeutic accuracy and efficacy. PubMed, Medline, Cochrane Library, Web of Science, and Google Scholar databases were extensively searched until October 2023. The methodological quality of the eligible articles was assessed using the Newcastle-Ottawa scale or Cochrane Risk of Bias tool. In addition, statistical analyses were performed using the Comprehensive Meta-Analysis software. Overall, 45 articles on EUS were included (28 on diagnostic role and 17 on therapeutic role). Pooled analysis demonstrated that EUS diagnostic tests had an accuracy of 92.4% for focal liver lesions (FLL) and 96.6% for parenchymal liver diseases. EUS-guided liver biopsies with either fine needle aspiration or fine needle biopsy had low complication rates when sampling FLL and parenchymal liver diseases (3.1% and 8.7%, respectively). Analysis of data from four studies showed that EUS-guided liver abscess had high clinical (90.7%) and technical success (90.7%) without significant complications. Similarly, EUS-guided interventions for the treatment of gastric varices (GV) have high technical success (98%) and GV obliteration rate (84%) with few complications (15%) and rebleeding events (17%). EUS in liver diseases is a promising technique with the potential to be considered a first-line therapeutic and diagnostic option in selected cases.

Endovascular embolization for basal ganglia and thalamic arteriovenous malformations.

Basal ganglia and thalamic arteriovenous malformations (AVMs) represent a special subset of malformations. Due to the involvement of vital brain structures and the specifically fine and delicate angioarchitecture of these lesions, it presents unique therapeutic challenges and technical difficulties that require thorough treatment planning, individualized treatment strategies, and advanced techniques for good clinical outcome. In this study, we presented a series of ruptured basal ganglia and thalamic AVMs embolized via a transarterial, transvenous or combined approach. Herein, we summarized our treatment experience and clinical outcomes to further evaluate the effectiveness and safety of endovascular embolization for these AVMs as well as the indications, therapy strategies, and techniques of embolization procedures. Twelve patients with basal ganglia and thalamus AVMs were included in the study. Their average age was 23.83 ± 16.51 years (range, 4-57 years) with a female predominance of 67% at presentation. The AVMs were located in the thalamus in 3 (25%) patients, in the basal ganglia in 3 (25%) patients, and in both sites of the brain in 6 (50%) patients. There were 5 AVMs located on the left side and 7 on the right. The mean nidus diameter was 3.32 ± 1.43 cm (range 1.3-6.1 cm). According to the Spetzler-Martin grading classification, 4 (33.3%) brain AVMs were Grade III, 7 (58.3%) were Grade IV, and 1 (8.3%) was Grade V. All of them presented with bleeding at admission: four of these patients presented with an intracerebral hemorrhage (ICH), 8 ICH in combination with intraventricular hemorrhage (IVH), and no patient with subarachnoid hemorrhage (SAH). Among these patients treated with endovascular embolization, 7 patients were treated by the transarterial approach, 4 patients transvenous approach, and 1 patient underwent the combined approach. A single embolization procedure was performed in 6 patients (50%) and the other 6 cases (50%) were treated in a staged manner with up to three procedures. Procedure-related complications occurred only in two patient (16.7%). Complete AVM obliteration was obtained in 7 patients (58.3%), and partial obliteration was in 4 patients (33.3%). Overall, good or excellent outcomes were obtained in 7 patients (58.3%), and poor functional outcome was observed in 5 patients (41.7%) at the last follow-up. All survived patients achieved anatomic stabilization and there was no postoperative bleeding or recurrence in the follow-up. The management of the basal ganglia and thalamic AVMs is a great challenge, which needs multimodal individualized treatment to improve the chances of radiographic cure and good outcomes. Endovascular therapy is safe and effective in the treatment of cerebral AVMs particularly for deep-seated AVMs such as the basal ganglia and thalamus. Our results demonstrate a high rate of anatomic obliteration with an acceptable rate of complications in the endovascular treatment of these vasculopathies via a transarterial approach or a transvenous approach.

Safety and efficacy of the pipeline embolization device for treatment of small vs. large aneurysms: a systematic review and meta-analysis.

Flow diversion with the pipeline embolization device (PED) is increasingly used to treat intracranial aneurysms with high obliteration rates and low morbidity. However, long-term (≥ 1year) angiographic and clinical outcomes still require further investigation. The aim of this study was to compare the occlusion and complication rates for small (< 10mm) versus large (10-25mm) aneurysms at long-term following treatment with PED. A systematic review and meta-analysis were performed in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. We conducted a comprehensive search of English language databases including Ovid MEDLINE and Epub Ahead of Print, In-Process, and Daily, Ovid EMBASE, Ovid Cochrane Central Register of Controlled Trials, Ovid Cochrane Database of Systematic Reviews, and Scopus. Our studies included a minimum of 10 patients treated with PED for small vs. large aneurysms and with at least 12months of follow-up. The primary safety endpoint was the rate of clinical complications measured by the occurrence of symptomatic stroke (confirmed clinically and radiographically), intracranial hemorrhage, or aneurysmal rupture. The primary efficacy endpoint was the complete aneurysm occlusion rate. Our analysis included 19 studies with 1277 patients and 1493 aneurysms. Of those, 1378 aneurysms met our inclusion criteria. The mean age was 53.9years, and most aneurysms were small (89.75%; N = 1340) in women (79.1%; N = 1010). The long-term occlusion rate was 73% (95%, CI 65 to 80%) in small compared to 84% (95%, CI 76 to 90%) in large aneurysms (p < 0.01). The symptomatic thromboembolic complication rate was 5% (95%, CI 3 to 9%) in small compared to 7% (95%, CI 4 to 13%) in large aneurysms (p = 0.01). The rupture rate was 2% vs. 4% (p = 0.92), and the rate of intracranial hemorrhage was 2% vs. 4% (p = 0.96) for small vs. large aneurysms, respectively; however, these differences were not statistically significant. The long-term occlusion rate after PED treatment is higher in large vs. small aneurysms. Symptomatic thromboembolic rates with stroke are also higher in large vs. small aneurysms. The difference in the rates of aneurysm rupture and intracranial hemorrhage was insignificant. Although the PED seems a safe and effective treatment for small and large aneurysms, further studies are required to clarify how occlusion rate and morbidity are affected by aneurysm size.

Endoluminal flow diversion as a primary treatment strategy for pediatric traumatic intracranial aneurysms: a case-based review of literature.

Traumatic intracranial aneurysms (TICAs) constitute a notable portion of pediatric intracranial aneurysms. Their unstable structure dictates a high incidence of rupture or mass effect from enlarging unruptured aneurysms, necessitating prompt diagnosis and treatment. TICAs often lack a true neck or are wide-necked, making them unsuitable for coil embolization and surgical clipping, and their fragile nature poses a risk of rupture during surgical and intrasaccular interventions. Endoluminal flow diverters (FD), deployed without requiring direct access to the aneurysmal sac, have emerged as an appealing sole treatment modality for TICAs. However, the clinical experience with this technique remains limited in the pediatric population. We describe the successful treatment of a paraclinoid TICA in a 4-year-old female using an endoluminal FD alone. Additionally, we conducted a literature review to assess the safety and effectiveness of this treatment modality in pediatric TICAs. Endoluminal flow diversion led to complete aneurysm obliteration in our case, with no observed complication, at the 9-month follow-up. Our review of the previously reported pediatric TICAs managed by standalone flow diversion highlights this technique as safe, efficient, and promising as a sole treatment modality, particularly in the anterior circulation, with a high rate of persistent total obliteration and a low rate of complications. However, the requirement for long-term antiplatelet therapy with the possibility of frequent dose monitoring and adjustments warrants special attention when using endoluminal FDs. Until guidelines specifically addressing optimal antiplatelet therapy in children with intracranial FDs are formulated, adherence to existing protocols is imperative to avoid in-stent thrombosis. Our literature review and personal experience indicate that endoluminal flow diversion can be a viable treatment approach for pediatric TICAs. However, prospective studies with extensive follow-ups are required to assess the durability of endoluminal FDs in treating pediatric TICAs, considering the long life expectancy of this demographic.

Preradiosurgical Embolization of Arteriovenous Malformations Reduces Target Volume – The Main Determinant for Complete Obliteration

Embolization and stereotactic radiosurgery (SRS) have increasingly been used to treat complex arteriovenous malformations (AVMs). We studied outcomes of AVM patients treated through a multidisciplinary approach, examined the effect of embolization on SRS success, and analyzed predictors of treatment failure. We retrospectively reviewed a prospectively maintained database of patients with AVMs treated with Gamma Knife (Leksell) SRS over an 11-year period. Patients with incomplete medical records and follow-up <2years were excluded. Demographics, clinical presentation, previous rupture history, angiographic nidus size, Spetzler-Martin (S-M) grade, adjunctive endovascular embolization and microsurgical resection, radiologic evidence of obliteration and hemorrhage, and clinical outcomes (modified Rankin Scale [mRS] scores) were recorded. Radiosurgery-related details including nidus volume and number of sessions and radiosurgery-, embolization-, and resection-associated complications were also recorded. Eighty-three patients (mean age, 41.0 ± 21.3years) were included. Mean reduction in AVM nidus target volume with endovascular embolization was 66.0 ± 19.7%. S-M grade reduction was achieved in 51.6% cases. Total obliteration after SRS was achieved in 56 AVMs (67.5%) after 2years, and in 38 (86.4%) after 4years. Two (2.4%) patients had rehemorrhage after SRS. Overall complication rate was 3.6%. Median angiographic follow-up was 55.5months. Favorable outcomes (mRS=0-2) were seen in 77.1%. SRS target volume was an independent predictor of treatment failure regardless of pre-SRS embolization. High AVM obliteration rates were achieved with judicious use of radiosurgery alone or with embolization. Embolization reduced target nidus volume by an average of 66%. SRS target volume was an independent predictor of treatment failure.

Long-term outcome of a tailored embolization strategy with Gamma Knife radiosurgery for high-grade brain arteriovenous malformations: a single-center experience.

The safety and efficacy of embolization with Gamma Knife radiosurgery (GKRS) for high-grade brain arteriovenous malformations (bAVMs) are uncertain. The purpose of this study was to elucidate the long-term outcome of a tailored embolization strategy with GKRS and identify the independent factors associated with bAVM obliteration. Between January 2014 and January 2017, a consecutive cohort of 159 patients with high-grade bAVMs who underwent embolization with GKRS was enrolled in this prospective single-center cohort study. All patients received a tailored embolization strategy with GKRS. The primary outcome was defined as bAVM obliteration. Secondary outcomes were neurological function and complications. After a mean follow-up of 40.4 months, 5 patients were lost to follow-up. One hundred eighteen of the remaining 154 patients had favorable neurological outcomes with complete bAVM obliteration. A decrease in bAVM nidus size was observed in 36 patients. Five patients developed intracranial hemorrhage during the latency period, and 2 patients died. The Kaplan-Meier analysis showed that the obliteration rate increased each year and reached the peak point at approximately 3 years. The multivariate Cox regression analysis of factors affecting bAVM obliteration revealed that postembolization bAVM volume < 10 cm3 (p = 0.02), supratentorial location (p < 0.01), staged embolization prior to GKRS (p < 0.01), and mean Spetzler-Martin (SM) grade (p < 0.01) were independent factors associated with a high obliteration rate. These data suggested that high-grade bAVMs treated using a tailored embolization strategy with GKRS were associated with a favorable clinical outcome and obliteration rate. Postembolization bAVM volume < 10 cm3, supratentorial location, staged embolization prior to GKRS, and low mean SM grade were associated with a high obliteration rate.

Treatment of high cervical arteriovenous fistulas in the craniocervical junction region.

The craniocervical junction (CCJ) is a complex region. Rarely, arteriovenous fistulas (AVFs) can occur in the CCJ region. Currently, it is accepted that CCJ AVFs should only refer to AVFs at the C1-C2 levels. It is reasonable to assume that high cervical CCJ AVFs are being referred to when discussing CCJ AVFs. High cervical CCJ AVFs can be divided into the following four types: dural AVF, radicular AVF, epidural AVF and perimedullary AVF. Until now, it was difficult to understand high cervical CCJ AVFs and provide a proper treatment for them. Therefore, an updated review of high cervical CCJ AVFs is necessary. In this review, the following issues are discussed: the definition of high cervical CCJ AVFs, vessel anatomy of the CCJ region, angioarchitecture of high cervical CCJ AVFs, treatment options, prognoses and complications. Based on the review and our experience, we found that the four types of high cervical CCJ AVFs share similar clinical and imaging characteristics. Patients may present with intracranial hemorrhage or congestive myelopathy. Treatment, including open surgery and endovascular treatment (EVT), can be used for symptomatic AVFs. Most high cervical CCJ AVFs can be effectively treated with open surgery. EVT remains challenging due to a high rate of incomplete obliteration and complications, and it can only be performed in superselective AVFs with simple angioarchitecture. Appropriate treatment can lead to a good prognosis.

Usefulness of silent magnetic resonance angiography for intracranial aneurysms treated with a flow re-direction endoluminal device.

Flow re-direction endoluminal device (FRED) is a novel dual-layer flow-diverting stent to treat cerebral aneurysms with high obliteration rates, however, it induces inevitable metal-related artifacts. We compared silent magnetic resonance angiography (MRA), a new MRA method using ultra-short time of echo and arterial spin-labeling, with conventional time-of-flight (TOF)-MRA for imaging aneurysms treated using FRED. Between May 2020 and September 2022, 16 patients with unruptured internal carotid aneurysms treated using FRED simultaneously underwent silent MRA and TOF-MRA after treatment, with 36 follow-up sessions in total. Two observers independently graded the quality of intra-aneurysmal flow and stented parent arteries under both types of MRA from 1 (not visible) to 4 (nearly equal to digital subtraction angiography [DSA]), with reference to DSA images as a standard criterion. The mean scores for intra-aneurysmal flow and stented parent arteries were significantly better for silent MRA (3.93 ± 0.21 and 3.82 ± 0.32, respectively) than for TOF-MRA (2.08 ± 0.99 and 1.92 ± 0.79, respectively) (P < 0.01). Intermodality agreements for intra-aneurysmal flow and stented parent arteries were 0.87 and 0.90, respectively. Silent MRA is superior to TOF-MRA for assessing patients treated with FRED, with potential as an alternative imaging modality to DSA.

Compactness index: a radiosurgery outcome predictor for patients with unruptured brain arteriovenous malformations.

The goal of the study was to define and quantify brain arteriovenous malformation (bAVM) compactness and to assess its effect on outcomes after Gamma Knife radiosurgery (GKRS) for unruptured bAVMs. Unsupervised machine learning with fuzzy c-means clustering was used to differentiate the tissue constituents of bAVMs on T2-weighted MR images. The percentages of vessel, brain, and CSF were quantified. The proposed compactness index, defined as the ratio of vasculature tissue to brain tissue, categorized bAVM morphology into compact, intermediate, and diffuse types according to the tertiles of this index. The outcomes of interest were complete obliteration and radiation-induced changes (RICs). A total of 209 unruptured bAVMs treated with GKRS were retrospectively included. The median imaging and clinical follow-up periods were 49.2 and 72.3 months, respectively. One hundred seventy-three bAVMs (82.8%) achieved complete obliteration after a median latency period of 43.3 months. The rates of RIC and permanent RIC were 76.1% and 3.8%, respectively. Post-GKRS hemorrhage occurred in 14 patients (6.7%), resulting in an annual bleeding risk of 1.0%. Compact bAVM, smaller bAVM volume, and exclusively superficial venous drainage were independent predictors of complete obliteration. Diffuse bAVM morphology, larger bAVM volume, and higher margin dose were independently associated with RICs. The compactness index quantitatively describes the compactness of unruptured bAVMs. Moreover, compact bAVMs may have a higher obliteration rate and a smaller risk of RICs than diffuse bAVMs. This finding could help guide decision-making regarding GKRS treatment for patients with unruptured bAVMs.

Gamma Knife Radiosurgery for Indirect Dural Carotid-Cavernous Fistula: Long-Term Ophthalmological Outcome.

Objective: The leading treatment option for dural carotid–cavernous sinus fistula is an endovascular approach with immediate improvement. Alternatively, radiosurgery is a slow response for obliterating the fistula and poses a radiation risk to the optic apparatus and the associated cranial nerves and blood vessels. In this study, we retrieved cases from a prospective database to assess the ophthalmological outcomes and complications in treating dural carotid cavernous sinus fistula with gamma knife radiosurgery (GKRS). Material and Methods: We retrieved a total of 65 cases of carotid cavernous sinus fistula treated with GKRS with margin dose of 18–20 Gy from 2003 to 2018 and reviewed the ophthalmological records required for our assessment. Results: The mean target volume was 2 ± 1.43 cc. The onset of symptom alleviated after GKRS was 3.71 ± 7.68 months. There were two cases with residual chemosis, two with cataract, two with infarction, one with transient optic neuropathy, and four with residual cranial nerve palsy, but none with glaucoma or dry eyes. In MRA analysis, total obliteration of the fistula was noted in 64 cases with no detectable ICA stenosis nor cavernous sinus thrombosis. In the Cox regression analysis, post-GKRS residual cranial nerve palsy was highly correlated to targeted volume (p < 0.05) and age (p < 0.05). The occurrence of post-GKRS cataract was related to the initial symptom of chemosis (p < 0.05). Conclusion: GKRS for carotid cavernous sinus fistula offers a high obliteration rate and preserves the cavernous sinus vascular structure while conferring a low risk of treatment complications such as adverse radiation risk to the optic apparatus and adjacent cranial nerves.

Repeat stereotactic radiosurgery for cerebral arteriovenous malformations.

The purpose of this retrospective, single-institution study was to evaluate radiological and clinical outcomes of patients managed with repeat stereotactic radiosurgery (SRS) for residual cerebral arteriovenous malformation (AVM) after prior SRS. The authors evaluated the clinical and radiological outcomes of consecutive patients treated with repeat single-session SRS for a residual brain AVM from 1989 to 2021. In total, 170 patients underwent repeat SRS for AVM (90 [52.9%] females; median [interquartile range] age at the first SRS procedure 28 [21.5] years; median [interquartile range] age at the second SRS procedure 32 [22.5] years). After repeat SRS, the actuarial 3-, 5-, and 10-year AVM obliteration rates were 37.6%, 57.3%, and 80.9%, respectively. Higher obliteration rates were associated with margin dose ≥ 19 Gy (p = 0.001). After the second SRS procedure, hemorrhage occurred in 8.2% of patients and was lethal in 1 patient. The risk factors of intracranial hemorrhage were age < 18 years (p = 0.03) and residual AVM diameter > 20 mm (p = 0.004). Lower obliteration rates were noted in patients with residual AVM diameter > 20 mm (p = 0.04) and those < 18 years of age (p = 0.04). Asymptomatic, symptomatic, and permanent radiation-induced changes (RICs) after the second SRS procedure occurred in 25.9%, 8.8%, and 5.3% of patients, respectively, and were associated with RIC after the first SRS procedure (p = 0.006). There was 1 case of a radiation-induced meningioma 12 years after SRS. Repeat SRS is a reasonable therapeutic option, in particular for patients with residual AVM. Repeat SRS was associated with more favorable outcomes in adult patients and those with residual AVM smaller than 20 mm in maximum diameter. To increase the rate of residual AVM obliteration, a prescription dose ≥ 19 Gy should ideally be used for repeat SRS.

Long-Term Risks of Hemorrhage and Adverse Radiation Effects of Stereotactic Radiosurgery for Brain Arteriovenous Malformations.

The information about long-term risks of hemorrhage and late adverse radiation effects (AREs) after stereotactic radiosurgery for brain arteriovenous malformations (AVMs) is lacking. To evaluate the long-term risks of hemorrhage and late ARE rates in patients with AVM treated with Gamma Knife surgery (GKS). We examined 1249 patients with AVM treated with GKS. The Spetzler-Martin grade was I in 313 patients (25%), II in 394 (32%), III in 458 (37%), and IV/V in 84 (7%). The median treatment volume was 2.5 cm3, and the median marginal dose was 20 Gy. The median follow-up period was 61 months. The 5- and 10-year nidus obliteration rates were 63% and 82%, respectively. The 5- and 10-year cumulative hemorrhage rates were 7% and 10%, respectively. The annual hemorrhage rate was 1.5% for the first 5 years post-GKS, which decreased to 0.5% thereafter. During the follow-up period, 42 symptomatic cyst formations/chronic encapsulated hematomas ([CFs/CEHs], 3%) and 3 radiation-induced tumors (0.2%) were observed. The 10- and 15-year cumulative CF/CEH rates were 3.7% and 9.4%, respectively. GKS is associated with reduced hemorrhage risk and high nidus obliteration rates in patients with AVM. The incidence of late AREs tended to increase over time. The most common ARE was CF/CEH, which can be safely removed; however, careful attention should be paid to the long-term development of fatal radiation-induced tumors.

Feasibility and Efficacy of Low-profile Visual Intraluminal Support Device: A Single Center Five-year Experience.

The Low-Profile Visualized Intraluminal Support (LVIS) devices are a new generation of self-expandable, high-porosity stents approved for the treatment of large to giant wide-necked intracranial aneurysms via stent-assisted coiling. Here we report the radiographic and clinical outcomes seen with LVIS, LVIS Jr. and LVIS Blue from a single institution over a fiveyear period. Patients with intracranial aneurysms treated by LVIS, LVIS Jr. and LVIS Blue technology over a five-year period (2012 - 2017) at our institution were retrospectively reviewed. Seventy-four patients (55 females and 19 males; average age = 59.2) with 74 aneurysms underwent embolization of intracranial aneurysms using LVIS (N = 10), LVIS Jr. (N = 47) or LVIS Blue (N = 12) devices at our institution over the study period. The most common location of treated aneurysms was the anterior communicating artery (31%), followed by the basilar artery (19%), and the middle cerebral artery (13%). The mean neck and dome sizes were 3.9±1.5mm and 6.6±3.2mm, respectively. The median follow-up time was 6 months. At the last radiographic follow- up, 93.1% of patients had complete occlusion (RR-I or OKM-D). In 5 cases (7%), the LVIS stent failed to open, requiring balloon angioplasty (N = 3) or stent recapture and use of a non-LVIS branded device (N = 2). Five patients had post-embolization infarcts, and 1 patient had an intra-operative dome rupture. LVIS brand of stents is a safe, effective, and technically feasible treatment strategy for wide-neck intracranial aneurysms, with high deployment success and aneurysm obliteration rates.

Abstract 1122‐000060: Endovascular Treatment of Large Intracranial Aneurysms Using Large Volume Coils: Safety and Efficacy

Introduction : Large volume coils in the treatment of intracranial aneurysms have demonstrated better packing density, shorter operative times, less number of coils per aneurysm and better cost‐effectiveness. However, most of the studies evaluated these coils in small or medium sized aneurysms. Therefore, our study aimed to determine our experience using large volume coils in the treatment of large intracranial aneurysms and determine its safety and efficacy. Methods : We retrospectively reviewed consecutive cases of intracranial aneurysms treated with Penumbra Coils 400 (PC400) at our institution between May 2016 and September 2019. Aneurysms &gt; 12 mm in maximal diameter were selected according to the ISUIA trial. Clinical and radiological variables were collected. The modified Rankin Scale (mRS) was used to determine the clinical outcome and was dichotomized (good clinical outcome: mRS £2; poor clinical outcome: mRS &gt;2). The Raymond Roy occlusion classification (RROC) was used to determine obliterations rates. An adequate obliteration was defined as RROC 1 or 2. Categorical variables were expressed as percentages and continuous variables as mean ± standard deviation. Stata v14 software was used for the analysis. Results : Eighteen patients harboring 18 intracranial aneurysms were treated. The mean age was 55 ± 12 years and 14 patients (78%) were women. A good preoperative clinical condition was found in 13 patients (72%). Ten aneurysms were unruptured (56%) and eight were dysplastic (44%). Paraclinoid aneurysms were the most frequently treated (61%). The mean number of coils were 6.2/aneurysm. The mean maximal diameter and neck were 18.9 ± 4.3 mm, and 5.7 ± 2.6 mm, respectively. The mean aspect ratio (AR) was 4 ± 1.9. Coiling was used in 10 cases (56%) followed by stent‐assisted coiling in 7 cases (39%) and balloon‐assisted coiling in 1 case. An immediate adequate obliteration rate was found in 8 cases (44%). Intraoperative complications occurred in two patients in which a coil loop migrated to the parent artery and a stent was placed without clinical consequences. In twelve patients (67%), angiographic follow‐up was performed. The mean follow‐up duration was 9.7 months. Nine patients (75%) showed a complete obliteration (RROC 1), whereas in three patients a residual aneurysm was still present. A good postoperative clinical outcome at discharge was found in 14 patients (78%). Procedure‐related morbidity and mortality were not reported. Conclusions : Embolization with large volume coils is a safe and effective alternative to conventional coils, with high obliteration rates at mid‐term follow‐up. Longer duration of angiographic follow‐up are needed in order to confirm the results presented here.

Abstract 1122‐000078: C‐Guard Stent for the Treatment of Cervical Internal Carotid Artery Aneurysms: Report of 2 Cases

Introduction : C‐Guard carotid stent is a self‐expandable open cell stent covered with a double‐layer mesh which was developed for the treatment of internal carotid artery disease. Lower procedural and complications rates, as well as lower post‐operative infarctions are some advantages of this device. Nevertheless, the use of C‐Guard in the treatment of cervical internal carotid artery (ICA) aneurysms is scarce. Therefore, we present two cases in which the C‐Guard stent achieved complete angiographic occlusion at follow‐up. Methods : We identified two cases in which the C‐Guard carotid stent was used to treat symptomatic cervical ICA aneurysms. Angiographic follow‐up was performed. Results : Case 1: 47‐yo female presented left‐sided motor deficit. CT showed ischemic areas in the right hemisphere and CTA demonstrated an unruptured aneurysm in the C1 segment of the right ICA. The patient started dual antiplatelet therapy (DAPT) with aspirin and clopidogrel. A 6mm x 40 mm C‐Guard carotid stent was deployed without complications. One‐year follow‐up CTA showed complete obliteration of the aneurysm with reconstruction of the ICA. Case 2: 38‐yo male presented decreased left visual acuity. CTA and DSA showed an unruptured aneurysm in the C1 segment of the ICA. The patient started DAPT with aspirin and clopidogrel. A 7mm x 30 mm C‐Guard carotid stent was deployed without complications. Three‐month follow‐up DSA showed complete obliteration of the aneurysm with adequate filling of distal vessels. Conclusions : C‐Guard stent is a potential alternative to conventional carotid stents in the treatment of cervical ICA aneurysms with high obliteration rates at follow‐up.

Abstract 1122‐000061: Initial Experience Using the Transvenous Embolization for Intracranial Arteriovenous Malformations in a Reference Endovascular Center

Introduction : Transvenous embolization (TVE) is used in cases of arteriovenous malformations (AVMs) with specific characteristics such as small size (&lt;3 cm), deep location, single draining vein and the absence of adequate feeders. High complete obliteration rates have been reported. Therefore, our study aimed to analyze our initial experience using the TVE for treatment of AVMs. Methods : Between May 2018 and January 2021, consecutive patients who underwent TVE of AVMs were selected. Demographics, radiological and clinical variables were collected. The modified Rankin Scale (mRS) was used to determine clinical outcomes and was dichotomized (good clinical condition: mRS £2; poor clinical condition: mRS &gt;2). Complete obliteration was defined as the total absence of the nidus and vein, subtotal obliteration was defined as the embolization of &gt;95% of nidus and partial obliteration was defined as the embolization of &lt;95% of nidus. Procedure‐related complications were defined as those that occurred during the procedure and were divided as intraoperative rupture and thrombosis. Results : Twenty‐one patients harboring 21 AVMs were evaluated. Fourteen patients (67%) were women. The mean age was 24.5 ± 14.1 years (7 – 48 years). A good preoperative clinical condition was present in 20 patients. Twenty AVMs were ruptured (95.2%). The most frequent locations were thalamus/basal ganglia in 6 patients (29%), followed by temporal/insular in 5 patients (24%). Spetzler‐Martin grades III, II and I were present in 11, 9 and 1 patients, respectively. The mean number of feeders was 2.1 per AVM. The feeders arised from the MCA in 9 cases, followed by PCA in 5 cases, ACA and AChoA in 3 cases, AICA in 2 cases, and ECA and PCom in 1 case, respectively. The mean number of veins was 1.3 per AVM. Deep venous drainage was present in 12 cases (57%). The mean size of the AVM nidus was 15.7 ± 7.8 mm (3.7 – 34 mm). Previous trans‐arterial embolization was done in 10 patients (47.6%). Pre‐embolization hematoma evacuation was done in 4 patients (19%). An immediate complete obliteration was achieved in 18 patients (85.7%), whereas a subtotal and partial obliteration were achieved in 2 and 1 patients, respectively. A poor post‐operative clinical condition occurred in 4 patients (20%). Procedure‐related complications occurred in 4 patients (20%): 3 cases with intra‐operative rupture of the AVM nidus and 1 case of a thrombus in the M1 treated with stent retriever. Mortality occurred in 3 patients (14.2%) of which two presented intra‐operative rupture with intracerebral hematomas that required decompressive craniectomy. One patient presented a post‐operative bleeding of the AVM nidus that required external ventricular drainage and decompressive craniectomy. Follow‐up angiography was done in 4 cases with total obliteration of all the cases (100%). Conclusions : The transvenous approach has emerged as an alternative to trans‐arterial approach with high grades of immediate total obliteration rates, but with potential procedure‐related complications. Thus, this technique should be used in selected cases in order to achieve complete cure rates.

Exclusion treatment of ruptured and unruptured low-grade brain arteriovenous malformations: a systematic review.

To assess the obliteration rate, functional outcome, hemorrhagic complication, and mortality rates of exclusion treatment of low-grade brain arteriovenous malformations (BAVMs) (Spetzler and Martin grades (SMGs) 1 and 2), either ruptured or unruptured. Electronic databases-Ovid MEDLINE and PubMed-were searched for studies in which there was evidence of exclusion treatment of low-grade BAVMs treated either by endovascular, surgical, radiosurgical, or multimodality treatment. The primary outcome of interest was angiographic obliteration post-treatment and at follow-up. The secondary outcomes of interest were functional outcome (mRS), mortality rate, and hemorrhagic complication. Descriptive statistics were used to calculate rates and means. Eleven studies involving 1809 patients with low-grade BAVMs were included. Among these, 1790 patients treated by either endovascular, surgical, radiosurgical, or multimodality treatment were included in this analysis. Seventy-two percent of BAVMs were Spetzler-Martin grade II. The overall (i.e., including all exclusion treatment modalities) complete obliteration rate ranged from 36.5 to 100%. The overall symptomatic hemorrhagic complication rate ranged from 0 to 7.3%; procedure-related mortality ranged from 0 to 4.7%. Our systematic review of the literature reveals a high overall obliteration rate for low-grade BAVMs, either ruptured or unruptured, with low mortality rate and an acceptable post-treatment hemorrhagic complication rate. These results suggest that exclusion treatment of low-grade BAVMs may be safe and effective, regardless of the treatment modality chosen.

Treatments of unruptured brain arteriovenous malformations: A systematic review and meta-analysis.

Background:The best therapeutic option for unruptured brain arteriovenous malformations (bAVMs) patients is disputed.Objective:To assess the occurrence of obliteration and complications of patients with unruptured bAVMs after various treatments.Methods:A systematic literature search was performed in PubMed, EMBASE, Web of Science, and so on to identify studies fulfilling predefined inclusion criteria. Baseline, treatment, and outcomes data were extracted for statistical analysis.Results:We identified 28 eligible studies totaling 5852 patients. The obliteration rates were 98% in microsurgery group (95% confidence interval (CI): 96%–99%, I2 = 74.5%), 97% in surgery group (95%CI: 95%–99%, I2 = 18.3%), 87% in endovascular treatment group (95%CI: 80%–93%, I2 = 0.0%), and 68% in radiosurgery group (95%CI: 66%–69%, I2 = 92.0%). The stroke or death rates were 1% in microsurgery group (95%CI: 0%–2%, I2 = 0.0%), 0% in surgery group (95%CI: 0%–1%, I2 = 0.0%), 4% in endovascular treatment group (95%CI: 0%–8%, I2 = 85.8%), and 3% in radiosurgery group (95%CI: 3%–4%, I2 = 82.9%). In addition, the proportions of hemorrhage were 2% in microsurgery group (95%CI: 1%–4%, I2 = 0.0%), 23% in endovascular treatment group (95%CI: 7%–39%), and 12% in radiosurgery group (95%CI: 12%–13%, I2 = 99.2%). As to neurological deficit, the occurrence was 9% in microsurgery group (95%CI: 6%–11%, I2 = 94.1%), 20% in surgery group (95%CI: 13%–27%, I2 = 0.0%), 14% in endovascular treatment group (95%CI: 10%–18%, I2 = 64.0%), and 8% in radiosurgery group (95%CI: 7%–9%, I2 = 66.6%).Conclusions:We found that microsurgery might provide lasting clinical benefits in some unruptured bAVMs patients for its high obliteration rates and low hemorrhage. These findings are helpful to provide a reference basis for neurosurgeons to choose the treatment of patients with unruptured bAVMs.