Tag: embolization

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Primary Embolization of Cerebral Arteriovenous Malformations With Intention to Cure: A Systematic Review of Literature and Meta-Analysis

Neurosurgery 95:1232–1244, 2024

The treatment of brain arteriovenous malformations (AVMs) involves multiple approaches, including embolization, microsurgical resection, and radiosurgery. With the advent of new embolisates, dual-lumen balloon catheters, detachable tip microcatheters, and transvenous embolization, endovascular AVM obliteration has become more effective. Although adjuvant embolization and embolization are commonly used, the safety and effectiveness of curative embolization remain unclear.

METHODS: We conducted a systematic literature review using PubMed, Ovid Medline, and Web of Science to identify studies reporting outcomes in patients with AVMs who underwent primary embolization with the intention to cure. We collected data on patient characteristics, AVM features, complications, and radiographic and clinical outcomes for meta-analysis.

RESULTS: We identified 25 studies with a total of 1425 patients with 1427 AVMs who underwent curative embolization. Of these patients, 70% were low grade (pooled = 61% [39-82]), 67% were <3 cm (pooled = 78% [60-92]), and 75% were in superficial locations (pooled = 80% [72-86]). At last radiographic follow-up (mean, 16.7 ± 10.9 months), the full obliteration rate was 52% (pooled = 61% [43-77]) and retreatment rate was 25% (pooled = 17% [8.3-27]). At last clinical follow-up (mean, 24.2 ± 13.3 months), the poor clinical outcome rate was 7.9% (pooled = 4.4% [1.3-8.7]) and symptomatic complication rate was 13% (pooled = 13% [8-19]). There was no significant difference in the rate of radiographic cure, need for retreatment, and poor outcomes between ruptured and unruptured AVMs. Symptomatic complications were more common in the treatment of unruptured AVMs. The primary outcomes showed high heterogeneity (I ² = 72%-94%).

CONCLUSION: Curative embolization of AVM is primarily reserved for small and low-grade AVMs, with highly variable outcomes. Our findings suggest poor radiographic outcomes and increased risk of complications. Outcomes are highly dependent on patient selection and technique used. Large multicenter prospective studies are required to further guide patient selection, categorize clinical and radiographic outcomes, and identify subgroup of patients that may benefit from curative embolization.

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Intraorbital Arteriovenous Fistulas: Case Series and Systematic Review

Operative Neurosurgery 27:23–30, 2024

Intraorbital arteriovenous fistulas (AVFs) are an extremely rare subtype of intracranial fistula with ophthalmic symptoms similar to cavernous sinus dural AVFs or carotid cavernous fistulas but worse visual outcomes. Here, we present a case series and thorough systematic review on intraorbital AVFs to demonstrate treatment modalities and address this rare type of AVF.

METHODS: We conducted a retrospective study at a single center, in which we identified all cases of intraorbital AVFs that occurred between 2002 and 2022. We collected and analyzed data on demographics, fistula characteristics, treatment methods, clinical outcomes, and fistula closure. In addition, we conducted a systematic review of intraorbital AVFs.

RESULTS: Seven cases in our center and 41 cases of intraorbital AVFs reported in the 35 articles were identified. At our center, transarterial embolization (TAE) (42.9%) alone resulted in immediate complete occlusion in 3 cases. Transvenous embolization (14.3%) resulted in one case of immediate complete occlusion. In 2 cases, surgery (28.6%) resulted in immediate complete occlusion. In one case, conservative treatment (14.3%) was used, and the fistula was eventually spontaneously occluded. Immediate complete occlusion rate was 85.7%. One blindness occurred (14.3%). In the literature reported, 3 cases (60%) of retinal artery occlusion were reported when performing TAE via the ophthalmic artery. Two fistulas recurred as reported. In 33 (80.5%) patients, the fistula was finally completely occluded.

CONCLUSION: TAE via the ophthalmic artery carries a high risk of blindness and a low cure rate. Transvenous techniques such as conventional transvenous routes, surgical exposure, or direct puncture of the drainage vein have been used as the first line of treatment for intraorbital AVFs.

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Transarterial Embolization of Dural Arteriovenous Fistulas: Conventional, Pressure Cooker, and Microballoon Catheter Embolization Techniques

Operative Neurosurgery 27:65–71, 2024

Dural fistulas are abnormal connections between dural arteries and intracranial veins treated mainly endovascularly in most settings. The aim was to examine a single-institution experience of microballoon catheter transarterial embolization (TAE) of dural arteriovenous fistulas (dAVFs) and compare it with other TAE techniques.

METHODS: We retrospectively identified all dAVFs treated at our institution between 2017 and 2022 with microballoon, conventional, and pressure cooker TAE. We studied occlusion and retreatment rates, treatment-related complications, and radiation doses.

RESULTS: During the study period, 66 patients underwent 75 TAE procedures to treat 68 dAVFs: 47 conventional TAE, 14 pressure cooker TAE, and 14 microballoon TAE. Median age of the study population was 63 years with 32% females. The most common dAVF location was the transverse sinus and 20% of dAVFs presented with hemorrhage. At 3-month follow-up, stable complete occlusion of the dAVF was seen in 72% (n = 34) after conventional TAE, 79% (n = 11) after pressure cooker TAE, and 86% (n = 12) after microballoon TAE. Retreatment was required in 19% (n = 9) after conventional TAE, 7% (n = 1) after pressure cooker TAE, and 7% (n = 1) after microballoon TAE. Treatment-related complications occurred in 17% (n =) after conventional TAE, 29% (n = 4) after pressure cooker TAE, and 7% (n = 1) after microballoon TAE.

CONCLUSION: In our experience, microballoon TAE of dAVFs resulted in better initial and 3-month angiographic outcomes and required less retreatment than conventional TAE. Microballoon TAE also resulted in fewer treatmentrelated complications than other techniques. In our experience, microballoon TAE is a reliable and safe endovascular technique to treat dAVFs.

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Radiosurgery With Prior Embolization Versus Radiosurgery Alone for Intracranial Arteriovenous Malformations

Neurosurgery 94:478–496, 2024

The addition of adjuvant embolization to radiosurgery has been proposed as a means of improving treatment outcomes of intracranial arteriovenous malformations (AVMs). However, the relative efficacy and safety of radiosurgery with adjuvant embolization vs radiosurgery alone remain uncertain. Moreover, previous systematic reviews and meta-analyses have included a limited number of studies and did not consider the effects of baseline characteristics, including AVM volume, on the outcomes. This systematic review aimed to evaluate the efficacy of preradiosurgery embolization for intracranial AVMs with consideration to matching status between participants in each treatment group.

METHODS: A systematic review and meta-analysis were conducted by searching electronic databases, including PubMed, Scopus, and Cochrane Library, up to January 2023. All studies evaluating the utilization of preradiosurgery embolization were included.

RESULTS: A total of 70 studies (9 matched and 71 unmatched) with a total of 12 088 patients were included. The mean age of the included patients was 32.41 years, and 48.91% of the patients were female. Preradiosurgery embolization was used for larger AVMs and patients with previous hemorrhage (P < .01, P = .02, respectively). The obliteration rate for preradiosurgery embolization (49.44%) was lower compared with radiosurgery alone (61.42%, odds ratio = 0.56, P < .01), regardless of the matching status of the analyzed studies. Although prior embolization was associated higher rate of cyst formation (P = .04), it lowered the odds of radiation-induced changes (P = .04). The risks of minor and major neurological deficits, postradiosurgery hemorrhage, and mortality were comparable between groups.

CONCLUSION: This study provides evidence that although preradiosurgery embolization is a suitable option to reduce the AVM size for future radiosurgical interventions, it may not be useful for same-sized AVMs eligible for radiosurgery. Utilization of preradiosurgery embolization in suitable lesions for radiosurgery may result in the added cost and burden of an endovascular procedure.

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Middle Meningeal Artery Embolization Versus Conventional Management for Patients With Chronic Subdural Hematoma: A Systematic Review and Meta-Analysis

Neurosurgery 92:1142–1154, 2023

The results from studies that compare middle meningeal artery (MMA) embolization vs conventional management for patients with chronic subdural hematoma are varied.

OBJECTIVE: To conduct a systematic review and meta-analysis on studies that compared MMA embolization vs conventional management.

METHODS: Medline, PubMed, and Embase databases were searched. Primary outcomes were treatment failure and surgical rescue; secondary outcomes were complications, follow-up modified Rankin scale > 2, mortality, complete hematoma resolution, and length of hospital stay (day). The certainty of the evidence was determined using the GRADE approach.

RESULTS: Nine studies yielding 1523 patients were enrolled, of which 337 (22.2%) and 1186 (77.8%) patients received MMA embolization and conventionalmanagement, respectively.MMA embolization was superior to conventional management for treatment failure (relative risk [RR] = 0.34 [0.14-0.82], P = .02), surgical rescue (RR = 0.33 [0.14-0.77], P = .01), and complete hematoma resolution (RR = 2.01 [1.10-3.68], P = .02). There was no difference between the 2 groups for complications (RR= 0.93 [0.63-1.37], P = .72), follow-up modified Rankin scale >2 (RR= 0.78 [0.449-1.25], P= .31), mortality (RR= 1.05 [0.51-2.14], P = .89), and length of hospital stay (mean difference = 0.57 [ 2.55, 1.41], P = .57). ForMMAembolization, the number needed to treat for treatment failure, surgical rescue, and complete hematoma resolution was 7, 9, and 3, respectively. The certainty of the evidence was moderate to high for primary outcomes and low to moderate for secondary outcomes.

CONCLUSION: MMA embolization decreases treatment failure and the need for surgical rescue without furthering the risk of morbidity and mortality. The authors recommend considering MMA embolization in the chronic subdural hematoma management.

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Comparison of Single-Session, Neoadjuvant, and Adjuvant Embolization Gamma Knife Radiosurgery for Arteriovenous Malformation

Neurosurgery 92:986–997, 2023

The purpose of intracranial arteriovenous malformations (AVMs) treatment is to prevent bleeding or subsequent hemorrhage with complete obliteration. For large, difficult-to-treat AVMs, multimodal approaches including surgery, endovascular embolization, and gamma knife radiosurgery (GKRS) are frequently used.

OBJECTIVE: To analyze the outcomes of AVMs treated with single-session, neoadjuvant, and adjuvant embolization GKRS.

METHODS: We retrospectively reviewed a database of 453 patients with AVMs who underwent GKRS between January 2007 and December 2017 at our facility. The obliteration rate, incidence of latent period bleeding, cyst formation, and radiation-induced changes were compared among the 3 groups, neoadjuvant-embolized, adjuvant-embolized, nonembolized group. In addition, the variables predicting AVM obliteration and complications were investigated.

RESULTS: A total of 228 patients were enrolled in this study. The neoadjuvant-embolized, adjuvant-embolized, and nonembolized groups comprised 29 (12.7%), 19 (8.3%), and 180 (78.9%) patients, respectively. Significant differences were detected among the 3 groups in the history of previous hemorrhage and the presence of aneurysms (P < .0001). Multivariate Cox regression analyses revealed a significant inverse correlation between neoadjuvant embolization and obliteration occurring 36 months after GKRS (hazard ratio, 0.326; P = .006).

CONCLUSION: GKRS with either neoadjuvant or adjuvant embolization is a beneficial approach for the treatment of AVMs with highly complex angioarchitectures that are at risk for hemorrhage during the latency period. Embolization before GKRS may be a negative predictive factor for late-stage obliteration (>36 months). To confirm our conclusions, further studies involving a larger number of patients and continuous follow-up are necessary.

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Microsurgery versus Microsurgery With Preoperative Embolization for Brain Arteriovenous Malformation Treatment: A Systematic Review and Meta-analysis

Neurosurgery 92:27–41, 2023

Preoperative embolization has traditionally been regarded as a safe and effective adjunct to microsurgical treatment of brain arteriovenous malformations (bAVM). However, there is currently no high-level evidence to ascertain this presumption.

OBJECTIVE: To compare the outcomes of microsurgery (MS) vs microsurgery with preoperative embolization (E + MS) in patients with bAVM through systematic review.

METHODS: We searched MEDLINE, PubMed, and Embase. The primary outcome was bAVM obliteration. Secondary outcomes were intraoperative bleeding (mL), complications, worsened modified Rankin Scale (mRS), and mortality. The pooled proportions of outcomes were calculated through the logit transformation method. The odds ratio (OR) of categorical data and mean difference of continuous data were estimated through the Mantel-Haenszel and the inverse variance methods, respectively.

RESULTS: Thirty-two studies met the eligibility criteria. One thousand eight hundred twenty-eight patients were treated by microsurgery alone, and 1088 were treated by microsurgery with preoperative embolization, respectively. The meta-analysis revealed no significant difference in AVM obliteration (94.1% vs 95.6%, OR = 1.15 [0.63-2.11], P = .65), mortality (1.7% vs 2%, OR = 0.88 [0.30-2.58], P = .82), procedural complications (18.2% vs 27.2%, OR = 0.47 [0.19-1.17], P = .10), worsened mRS (21.2% vs 18.5%, OR = 1.08 [0.33-3.54], P = .9), and intraoperative blood loss (mean difference = 182.89 [À87.76, 453.55], P = .19).

CONCLUSION: The meta-analysis showed no significant difference in AVM obliteration, mortality, complications, worse mRS, and intraoperative blood loss between MS and E + MS groups. For AVMs where MS alone has acceptable results, it is reasonable to bypass unnecessary preoperative embolization given higher postoperative complication risk.

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Solid vs. cystic predominance in posterior fossa hemangioblastomas: implications for cerebrovascular risks and patient outcome

Acta Neurochirurgica (2022) 164:1357–1364

Hemangioblastomas (HGBs) are highly vascular benign tumors, commonly located in the posterior fossa, and 80% of them are sporadic. Patients usually present with features of raised intracranial pressure and cerebellar symptoms. HGB can be classified as either mostly cystic or solids. Although the solid component is highly vascularized, aneurysm or hemorrhagic presentation is rarely described, having catastrophic results.

Methods We identified 32 consecutive patients with posterior fossa HBG who underwent surgery from 2008 through 2020 at our medical center. Tumors were classified as predominantly cystic or solid according to radiological features. Resection was defined as gross total (GTR) or subtotal (STR).

Results During the study period, 32 posterior fossa HGBs were resected. There were 26 cerebellar lesions and 4 medullar lesions, and in 2 patients, both structures were affected. Predominant cystic tumors were seen in 15 patients and solids in 17. Preoperative digital subtraction angiography (DSA) was performed in 8 patients with solid tumors, and 4 showed tumor-related aneurysms. Embolization of the tumors was performed in 6 patients, including the four tumor-related aneurysms. GTR was achieved in 29 tumors (91%), and subtotal resection in 3 (9%). Three patients had postoperative lower cranial nerve palsy. Functional status was stable in 5 patients (16%), improved in 24 (75%), and 3 patients (9%) deteriorated. One patient died 2 months after the surgery. Two tumors recurred and underwent a second surgery achieving GTR. The mean follow-up was 42.7 months (SD ± 51.0 months).

Conclusions Predominant cystic HGB is usually easily treated as the surgery is straightforward. Those with a solid predominance present a more complex challenge sharing features similar to arteriovenous malformations. Given the important vascular association of solid predominance HGB with these added risk factors, the preoperative assessment should include DSA, as in arteriovenous malformations, and endovascular intervention should be considered before surgery.

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Intervention for unruptured high-grade intracranial dural arteriovenous fistulas: a multicenter study

J Neurosurg 136:962–970, 2022

The risk-to-benefit profile of treating an unruptured high-grade dural arteriovenous fistula (dAVF) is not clearly defined. The aim of this multicenter retrospective cohort study was to compare the outcomes of different interventions with observation for unruptured high-grade dAVFs.

METHODS The authors retrospectively reviewed dAVF patients from 12 institutions participating in the Consortium for Dural Arteriovenous Fistula Outcomes Research (CONDOR). Patients with unruptured high-grade (Borden type II or III) dAVFs were included and categorized into four groups (observation, embolization, surgery, and stereotactic radiosurgery [SRS]) based on the initial management. The primary outcome was defined as the modified Rankin Scale (mRS) score at final follow-up. Secondary outcomes were good outcome (mRS scores 0–2) at final follow-up, symptomatic improvement, all-cause mortality, and dAVF obliteration. The outcomes of each intervention group were compared against those of the observation group as a reference, with adjustment for differences in baseline characteristics.

RESULTS The study included 415 dAVF patients, accounting for 29, 324, 43, and 19 in the observation, embolization, surgery, and SRS groups, respectively. The mean radiological and clinical follow-up durations were 21 and 25 months, respectively. Functional outcomes were similar for embolization, surgery, and SRS compared with observation. With observation as a reference, obliteration rates were higher after embolization (adjusted OR [aOR] 7.147, p = 0.010) and surgery (aOR 33.803, p < 0.001) and all-cause mortality was lower after embolization (imputed, aOR 0.171, p = 0.040). Hemorrhage rates per 1000 patient-years were 101 for observation versus 9, 22, and 0 for embolization (p = 0.022), surgery (p = 0.245), and SRS (p = 0.077), respectively. Nonhemorrhagic neurological deficit rates were similar between each intervention group versus observation.

CONCLUSIONS Embolization and surgery for unruptured high-grade dAVFs afforded a greater likelihood of obliteration than did observation. Embolization also reduced the risk of death and dAVF-associated hemorrhage compared with conservative management over a modest follow-up period. These findings support embolization as the first-line treatment of choice for appropriately selected unruptured Borden type II and III dAVFs.

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Middle Meningeal Artery Embolization Versus Conventional Treatment of Chronic Subdural Hematomas

Neurosurgery 89:486–495, 2021

Middle meningeal artery (MMA) embolization is an emerging minimally invasive endovascular technique for chronic subdural hematoma (cSDH). Currently, limited literature exists on its safety and efficacy compared with conventional treatment (open- surgical-evacuation-only).

OBJECTIVE: To compare MMA embolization to conventional treatment.

METHODS: Retrospective analysis of patients with cSDHs treated with MMA embolization in a single center from 2018 to 2019 was performed. Comparisons were made with a historical conventional treatment cohort from 2006 to 2016. Propensity score matching analysis was used to assemble a balanced group of subjects.
RESULTS: A total of 357 conventionally treated cSDH and 45 with MMA embolization were included. After balancing with propensity score matching, a total of 25 pairs of cSDH were analyzed. Comparing the embolization with the conventional treatment group yielded no significant differences in complications (4% vs 4%; P > .99), clinical improvement (82.6% vs 83.3%; P = .95), cSDH recurrence (4.3% vs 21.7%; P = .08), overall re-intervention rates (12% vs 24%; P = .26), modified Rankin scale >2 on last follow-up (17.4% vs 32%; P = .24), as well as mortality (0% vs 12%; P = .09). Radiographic improvement at last follow-up was significantly higher in the open surgery cohort (73.9% vs 95.6%; P = .04). However, there was a trend for lengthier last follow-up for the historical cohort (72 vs 104 d; P = .07).

CONCLUSION: There was a trend for lower recurrence and mortality rates in the embolization era cohort. There were significantly higher radiological improvement rates on last follow-up in the surgical only cohort era. There were no significant differences in complications and clinical improvement.

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Stereotactic radiosurgery with versus without prior Onyx embolization for brain arteriovenous malformations

J Neurosurg 135:742–750, 2021

Investigations of the combined effects of neoadjuvant Onyx embolization and stereotactic radiosurgery (SRS) on brain arteriovenous malformations (AVMs) have not accounted for initial angioarchitectural features prior to neuroendovascular intervention. The aim of this retrospective, multicenter matched cohort study is to compare the outcomes of SRS with versus without upfront Onyx embolization for AVMs using de novo characteristics of the preembolized nidus.

METHODS The International Radiosurgery Research Foundation AVM databases from 1987 to 2018 were retrospectively reviewed. Patients were categorized based on AVM treatment approach into Onyx embolization (OE) and SRS (OE+SRS) or SRS alone (SRS-only) cohorts and then propensity score matched in a 1:1 ratio. The primary outcome was AVM obliteration. Secondary outcomes were post-SRS hemorrhage, all-cause mortality, radiological and symptomatic radiation-induced changes (RICs), and cyst formation. Comparisons were analyzed using crude rates and cumulative probabilities adjusted for competing risk of death.

RESULTS The matched OE+SRS and SRS-only cohorts each comprised 53 patients. Crude rates (37.7% vs 47.2% for the OE+SRS vs SRS-only cohorts, respectively; OR 0.679, p = 0.327) and cumulative probabilities at 3, 4, 5, and 6 years (33.7%, 44.1%, 57.5%, and 65.7% for the OE+SRS cohort vs 34.8%, 45.5%, 59.0%, and 67.1% for the SRS-only cohort, respectively; subhazard ratio 0.961, p = 0.896) of AVM obliteration were similar between the matched cohorts. The secondary outcomes of the matched cohorts were also similar. Asymptomatic and symptomatic embolization-related complication rates in the matched OE+SRS cohort were 18.9% and 9.4%, respectively.

CONCLUSIONS Pre-SRS AVM embolization with Onyx does not appear to negatively influence outcomes after SRS. These analyses, based on de novo nidal characteristics, thereby refute previous studies that found detrimental effects of Onyx embolization on SRS-induced AVM obliteration. However, given the risks incurred by nidal embolization using Onyx, this neoadjuvant intervention should be used judiciously in multimodal treatment strategies involving SRS for appropriately selected large-volume or angioarchitecturally high-risk AVMs.

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Neuroform Atlas Stent for Treatment of Middle Cerebral Artery Aneurysms

Neurosurgery 89:102–108, 2021

Heterogeneous effect of endovascular aneurysm therapy has been observed across different anatomic locations. There is a paucity of data for stent-assisted coiling of middle cerebral artery (MCA) aneurysms.

OBJECTIVE: To present the results of the MCA aneurysmgroup from the Neuroform Atlas (Stryker Neurovascular) investigational device exemption (IDE) trial.

METHODS: The Atlas IDE trial is a prospective, multicenter, single-arm, open-label study of wide-neck aneurysms (neck ≥ 4 mm or dome-to-neck ratio < 2) in the anterior circulation treated with the Neuroform Atlas Stent and approved coils. Follow-up was obtained immediately postprocedure and 2, 6, and 12 mo postoperatively.We herein describe safety and efficacy outcomes, and functional independence of the subjects with aneurysms from all segments of MCA.

RESULTS: A total of 35 patients were included (27 MCA bifurcation, 5 M1, 3 M2). The mean aneurysm size was 6.0 ± 1.8 mm, and the mean neck was 4.4 ± 1.2 mm. Technical procedural success was achieved in all patients. A total of 26 patients had follow-up digital subtraction angiography available at 12mo, with 80.8% (21/26) having complete aneurysm occlusion. Twelve-month safety data were collected for 91.4% (32/35), 8.5% (3/35) had primary safety endpoint, all 3 major ischemic strokes. Mortality occurred in 2 patients beyond 30 d unrelated to procedure (1 gallbladder cancer and 1 fentanyl intoxication). At 1 yr, modified Rankin Score was 0 to 2 in 84.4% (27/32), 3 in 9.4%, and 3 patientswere missing. Approximately 5.7% (2/35) of patients were retreated at 12 mo.

CONCLUSION: Stent-assisted coiling with the Neuroform Atlas Stent is a viable alternative to clipping for selected MCA aneurysms. Complete aneurysm occlusion rates have improved compared to historical data. Proper case selection can lead to acceptable endovascular results.

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Observation Versus Intervention for Low-Grade Intracranial Dural Arteriovenous Fistulas

Neurosurgery 88:1111–1120, 2021

Low-grade intracranial dural arteriovenous fistulas (dAVF) have a benign natural history in the majority of cases. The benefit from treatment of these lesions is controversial.

OBJECTIVE: To compare the outcomes of observation versus intervention for low-grade dAVFs.

METHODS: We retrospectively reviewed dAVF patients from institutions participating in the CONsortium for Dural arteriovenous fistula Outcomes Research (CONDOR). Patients with low-grade (Borden type I) dAVFs were included and categorized into intervention or observation cohorts. The intervention and observation cohorts were matched in a 1:1 ratio using propensity scores. Primary outcome was modified Rankin Scale (mRS) at final follow-up. Secondary outcomes were excellent (mRS 0-1) and good (mRS 0-2) outcomes, symptomatic improvement, mortality, and obliteration at final follow-up.

RESULTS: The intervention and observation cohorts comprised 230 and 125 patients, respectively. We found no differences in primary or secondary outcomes between the 2 unmatched cohorts at last follow-up (mean duration 36 mo), except obliteration rate was higher in the intervention cohort (78.5% vs 24.1%, P < .001). The matched intervention and observation cohorts each comprised 78 patients. We also found no differences in primary or secondary outcomes between the matched cohorts except obliteration was also more likely in the matched intervention cohort (P < .001). Procedural complication rates in the unmatched and matched intervention cohorts were 15.4% and 19.2%, respectively.

CONCLUSION: Intervention for low-grade intracranial dAVFs achieves superior obliteration rates compared to conservative management, but it fails to improve neurological or functional outcomes. Our findings do not support the routine treatment of low-grade dAVFs.

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Spetzler-Martin Grade III Arteriovenous Malformations: A Multicenter Propensity-Adjusted Analysis of the Effects of Preoperative Embolization

Neurosurgery 88:996–1002, 2021

Spetzler-Martin (SM) grade III arteriovenous malformations (AVMs) are at the boundary of safe operability, and preoperative embolizationmay reduce surgical risks.

OBJECTIVE: To evaluate the benefits of preoperative AVM embolization by comparing neurological outcomes in patients with grade III AVMs treated with or without preoperative embolization.

METHODS: All microsurgically treated grade III AVMs were identified from 2011 to 2018 at 2medical centers. Neurological outcomes,measured as final modified Rankin Scale scores (mRS) and changes in mRS from preoperative baseline to last follow-up evaluation, were compared in patients with and without preoperative embolization.

RESULTS: Of the 102 patients with grade III AVMs who were treated microsurgically, 57 (56%) underwent preoperative embolization. Significant differences were found between the patients with and without embolization in AVM eloquence (74% vs 93%, P = .02), size ≥ 3 cm (47% vs 73%, P = .01), diffuseness (7% vs 22%, P = .04), and mean final mRS (1.1 vs 2.0, P = .005). Poor outcomes were more frequent in patients without embolization (38%) than with embolization (7%) (final mRS > 2; P < .001). Propensityadjusted analysis revealed AVM resection without embolization was a risk factor for poor outcome (mRS score > 2; odds ratio, 4.2; 95% CI, 1.1-16; P = .03).

CONCLUSION: Nonembolization of SM grade III AVMs is associated with an increased risk of poor neurological outcomes after microsurgical resection. Preoperative embolization of intermediate-grade AVMs selected because of large AVM size, surgical inaccessibility of feeding arteries, and high flow should be employed more often than anticipated, even in the context of increasing microsurgical experience with AVMs.

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Preoperative embolization versus no embolization for WHO grade I intracranial meningioma

J Neurosurg 134:693–700, 2021

The controversy continues over the clinical utility of preoperative embolization for reducing tumor vascularity of intracranial meningiomas prior to resection. Previous studies comparing embolization and nonembolization patients have not controlled for detailed tumor parameters before assessing outcomes.

METHODS The authors reviewed the cases of all patients who underwent resection of a WHO grade I intracranial meningioma at their institution from 2008 to 2016. Propensity score matching was used to generate embolization and nonembolization cohorts of 52 patients each, and a retrospective review of clinical and radiological outcomes was performed.

RESULTS In total, 52 consecutive patients who underwent embolization (mean follow-up 34.8 ± 31.5 months) were compared to 52 patients who did not undergo embolization (mean follow-up 32.8 ± 28.7 months; p = 0.63). Variables controlled for included patient age (p = 0.82), tumor laterality (p > 0.99), tumor location (p > 0.99), tumor diameter (p = 0.07), tumor invasion into a major dural sinus (p > 0.99), and tumor encasement around the internal carotid artery or middle cerebral artery (p > 0.99). The embolization and nonembolization cohorts did not differ in terms of estimated blood loss during surgery (660.4 ± 637.1 ml vs 509.2 ± 422.0 ml; p = 0.17), Simpson grade IV resection (32.7% vs 25.0%; p = 0.39), perioperative procedural complications (26.9% vs 19.2%; p = 0.35), development of permanent new neurological deficits (5.8% vs 7.7%; p = 0.70), or favorable modified Rankin Scale (mRS) score (a score of 0–2) at last follow-up (96.0% vs 92.3%; p = 0.43), respectively. When comparing the final mRS score to the preoperative mRS score, patients in the embolization group were more likely than patients in the nonembolization group to have an improvement in mRS score (50.0% vs 28.8%; p = 0.03).

CONCLUSIONS After controlling for patient age, tumor size, tumor laterality, tumor location, tumor invasion into a major dural sinus, and tumor encasement of the internal carotid artery or middle cerebral artery, preoperative meningioma embolization intended to decrease tumor vascularity did not improve the surgical outcomes of patients with WHO grade I intracranial meningiomas, but it did lead to a greater chance of clinical improvement compared to patients not treated with embolization.

 

 

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Embolization of Brain Arteriovenous Malformations With VersusWithout Onyx Before Stereotactic Radiosurgery

Neurosurgery 88:366–374, 2021

Embolization of brain arteriovenous malformations (AVMs) using ethylene-vinyl alcohol copolymer (Onyx) embolization may influence the treatment effects of stereotactic radiosurgery (SRS) differently than other embolysates.

OBJECTIVE: To compare the outcomes of pre-SRS AVM embolization with vs without Onyx through a multicenter, retrospective matched cohort study.

METHODS: We retrospectively reviewed International Radiosurgery Research Foundation AVM databases from 1987 to 2018. Embolized AVMs treated with SRS were selected and categorized based on embolysate usage into Onyx embolization (OE + SRS) or non-Onyx embolization (NOE + SRS) cohorts. The 2 cohorts were matched in a 1:1 ratio using de novo AVM features for comparative analysis of outcomes.

RESULTS: The matched cohorts each comprised 45 patients. Crude AVM obliteration rates were similar between the matched OE + SRS vs NOE + SRS cohorts (47% vs 51%; odds ratio [OR] = 0.837, P = .673). Cumulative probabilities of obliteration were also similar between the OE + SRS vs NOE + SRS cohorts (subhazard ratio = 0.992, P = .980). Rates of post-SRS hemorrhage, all-cause mortality, radiation-induced changes, cyst formation, and embolization-associated complications were similar between the matched cohorts. Sensitivity analysis for AVMs in the OE + SRS cohort embolized with Onyx alone revealed a higher rate of asymptomatic embolization-associated complications in this subgroup compared to the NOE + SRS cohort (36% vs 15%; OR = 3.297, P = .034), but the symptomatic complication rates were similar.

CONCLUSION: Nidal embolization using Onyx does not appear to differentially impact the outcomes of AVM SRS compared with non-Onyx embolysates. The embolic agent selected for pre-SRS AVM embolization should reflect both the experience of the neurointerven- tionalist and target of endovascular intervention.

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Stereotactic Radiosurgery With Versus Without Embolization for Brain ArteriovenousMalformations

Neurosurgery 88(2) 2021: 313–321

Prior comparisons of brain arteriovenous malformations (AVMs) treated using stereotactic radiosurgery (SRS) with or without embolization were inherently flawed, due to differences in the pretreatment nidus volumes.

OBJECTIVE: To compare the outcomes of embolization and SRS, vs SRS alone for AVMs using pre-embolization malformation features.

METHODS: We retrospectively reviewed International Radiosurgery Research Foundation AVM databases from 1987 to 2018. Patients were categorized into the embolization and SRS (E + SRS) or SRS alone (SRS-only) cohorts. The 2 cohorts were matched in a 1:1 ratio using propensity scores. Primary outcome was defined as AVM obliteration. Secondary outcomes were post-SRS hemorrhage, all-cause mortality, radiologic and symptomatic radiation-induced changes (RIC), and cyst formation.

RESULTS: The matched cohorts each comprised 101 patients. Crude AVM obliteration rates were similar between the matched E + SRS vs SRS-only cohorts (48.5% vs 54.5%; odds ratio = 0.788, P = .399). Cumulative probabilities of obliteration at 3, 4, 5, and 6 yr were also similar between the E + SRS (33.0%, 46.4%, 56.2%, and 60.8%, respectively) and SRSonly (32.9%, 46.2%, 56.0%, and 60.6%, respectively) cohorts (subhazard ratio (SHR)=1.005, P = .981). Cumulative probabilities of radiologic RIC at 3, 4, 5, and 6 yr were lower in the E + SRS (25.0%, 25.7%, 26.7%, and 26.7%, respectively) vs SRS-only (45.3%, 46.2%, 47.8%, and 47.8%, respectively) cohort (SHR = 0.478, P = .004). Symptomatic and asymptomatic embolization-related complication rates were 8.3% and 18.6%, respectively. Rates of post- SRS hemorrhage, all-cause mortality, symptomatic RIC, and cyst formation were similar between the matched cohorts.

CONCLUSION: This study refutes the prevalent notion that AVM embolization negatively affects the likelihood of obliteration after SRS.

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Predictors of Complications, Functional Outcome, and Morbidity in a Large Cohort TreatedWith Flow Diversion

Neurosurgery DOI:10.1093/neuros/nyz508

A dramatic improvement in obliteration rates of large, wide-necked aneurysms has been observed after the FDA approved the Pipeline Embolization Device (PED) in 2011.

OBJECTIVE: To assess the predictors of complications, morbidity, and unfavorable outcomes in a large cohort of patients with aneurysms treated with PED.

METHODS: A retrospective chart review of a prospectively maintained database for subjects treated with flow diversion from 2010 to 2019.

RESULTS: A total of 598 aneurysms were treated during a period extending from 2010 to 2019 (84.28% females, mean age 55.5 yr, average aneurysm size 8.49 mm). Morbidity occurred at a rate of 5.8% and mortality at a rate of 2.2%. Ischemic stroke occurred at a rate of 3%, delayed aneurysmal rupture (DAR) at 1.2%, and distal intraparenchymal hemorrhage (DIPH) at 1.5%. On multivariate analysis, the predictor of stroke was aneurysm size>15 mm. Predictors of DAR were previous subarachnoid hemorrhage (SAH), increasing aneurysm size, and posterior circulation aneurysm. Predictors of DIPH were using more than 1 PED and baseline P2Y12 value. Predictors of in-stent stenosis were the increasing year of treatment and balloon angioplasty, whereas increasing age and previous treatment were negatively associated with in-stent stenosis. Predictors of morbidity were posterior circulation aneurysms, increasing aneurysm size, and hypertension, and incidental aneurysm diagnosis was protective for morbidity.

CONCLUSION: Flow diversion is a safe and effective treatment option for aneurysms. A better understanding of predictive factors of complications, morbidity, and functional outcomes is of high importance for a more accurate risk assessment.

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Embolized cerebral arteriovenous malformations: a multivariate analysis of 101 excised specimens

J Neurosurg 132:1140–1146, 2020

Endovascular approaches have evolved from a technique practiced at very few centers to a widely available option in the management of arteriovenous malformations (AVMs) of the central nervous system. Embolization can be employed as definitive therapy or as an adjunct to surgical excision. A wide variety of embolic agents have been successfully developed and used in the clinical setting. In addition to facilitating vascular occlusion, embolic agents induce a number of reactive and destructive changes in vessel walls and the surrounding tissue. However, studies examining the pathological changes induced by different embolic agents and varying times of exposure are scarce. The goal of the present study was to compare embolic agents and time of exposure on the pathology in excised specimens.

METHODS The records of the Department of Pathology at the London Health Sciences Centre were searched for embolized AVMs for the 35-year period 1980–2015. All cases were reevaluated for clinical and technical variables and standardized histopathological findings. Cases were grouped by embolic agent, volume of agent used, and time to excision.

RESULTS A total of 101 specimens were identified. Embolic agents were invariably associated with a range of pathological findings, some of which may affect the integrity of vessel walls or the reestablishment of flow, thrombosis, acute and chronic inflammatory changes, angionecrosis, extravasation, and recanalization. The type of embolic agent did not predict differences in the incidence or severity of histopathological changes. Larger volumes of embolic agent were associated with a greater proportion of vessels containing embolic material. AVMs excised early (< 1 week postembolization) contained more acute vasculitis, while those excised later (≥ 1 week postembolization) were more likely to exhibit recanalization and foreign body giant cell infiltrates.

CONCLUSIONS Embolic agents induce a predictable range and temporal progression of pathological changes in cerebral AVMs. The embolic agents studied are indistinguishable in terms of the range and frequency of pathological reactions induced. Greater volumes of embolic agent are associated with more abundant agent within the lesion, but the proportion of vessels and vascular cross-sectional areas containing agent is small. Several changes are significantly associated with time postembolization. Acute vasculitis is a more common finding in the 1st week, while recanalization and foreign body–type granulomatous inflammation are more common at 1 week and beyond.

 

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Embolization of the middle meningeal artery in patients with chronic subdural hematoma—a systematic review and meta-analysis

Acta Neurochirurgica (2020) 162:777–784

Chronic subdural hematoma (CSDH) remains a neurosurgical condition with high recurrence rate after surgical treatment. The primary pathological mechanism is considered to be repeated microbleedings from fragile neo-vessels within the outer hematoma membrane. The neo-vessels are supplied from peripheral branches of the middle meningeal artery, and embolization of MMA (eMMA) has been performed to prevent re-bleeding episodes and thereby CSDH recurrence.

Objective To evaluate the published evidence for the effect of eMMA in patients with recurrent CSDH. Secondarily, to investigate the effect of eMMA as an alternative to surgery for primary treatment of CSDH. Method A systematic review of the literature on eMMA in patients with recurrent CSDH was conducted. PubMed, Embase, and Cochrane databases were reviewed using the search terms: Embolization, Medial Meningeal Artery, Chronic Subdural Haematoma, and Recurrence. Furthermore, the following mesh terms were used: Chronic Subdural Haematoma AND embolization AND medial meningeal artery AND recurrence. Eighteen papers were found and included. No papers were excluded. The number of patients with primary CSDH and the number of patients with recurrent CSDH treated with eMMA were listed. Furthermore, the number of recurrences in both categories was registered.

Results Eighteen papers with a total of 191 included patients diagnosed with CSDH treated with eMMA for primary and recurrent CSDH were identified. Recurrence rate for patients treated with eMMA for recurrent CSDH was found to be 2.4%, 95%CI (0.5%; 11.0%), whereas the recurrence rate for patients treated with eMMAfor primary CSDH was 4.1%, 95%CI (1.4%; 11.4%).

Conclusion eMMA is a minimally invasive procedure for treatment of CSDH. Although this study is limited by publication bias, it seems that this procedure may reduce recurrence rates compared with burr hole craniostomy for both primary and recurrent hematomas. A controlled study is warranted.

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