Lawton, Michael T.

Abstract Introduction The impact of multiple feeding arteries on clinical outcomes of cerebral arteriovenous malformations (AVMs) is not well understood. This study aims to compare outcomes between AVMs with multiple versus single feeding arteries. Patients and Methods Data from the Multicenter International Study for Treatment of Brain AVMs (MISTA) consortium were analyzed. Propensity score matching (PSM) was used to balance cohorts. Subgroup analysis was conducted for ruptured and unruptured AVMs and different treatment options, and multivariable logistic regression was applied to assess the impact of feeding artery origin. Results Among 953 patients, 661(69.4%) had multiple feeding arteries, and 292 (30.6%) had a single feeding artery. After PSM, which included 422 matched patients (211 in each group), the differences in obliteration rates (68.7% vs 74.8%, OR 0.73, 95% CI: 0.48–1.12, p = 0.16) and symptomatic complications (15.6% vs 11.8%, OR 1.37, 95% CI: 0.78–2.41, p = 0.25) were not significant. Subgroup analysis comparing ruptured and unruptured AVMs and different treatment options showed no significant differences across all subgroups. Multivariable analysis identified PICA feeders as significantly associated with increased odds of all complications (OR 7.33, 95% CI: 2.14–25.1, p = 0.002). Discussion and Conclusion AVMs with a single feeding artery were more likely to present with rupture, but no significant differences in obliteration rates or complications were observed between the groups after PSM. These findings suggest that while the number of feeding arteries may influence the initial presentation, it does not appear to impact overall treatment success or patient prognosis. Further prospective studies are needed to confirm these findings.

Background Brain arteriovenous malformations (AVMs) are abnormal connections between feeding arteries and draining veins, associated with significant risks of haemorrhage, seizures and other neurological deficits. Preoperative embolization is commonly used as an adjunct to microsurgical resection, with the aim of reducing intraoperative complications and improving outcomes. However, the efficacy and safety of this approach remain controversial. Methods This study is a subanalysis of the Multicenter International Study for Treatment of Brain AVMs consortium. We retrospectively analysed 486 patients with brain AVMs treated with microsurgical resection between January 2010 and December 2023. Patients were divided into two groups: those who underwent microsurgery alone (n=245) and those who received preoperative embolization, followed by microsurgery (n=241). Propensity score matching was employed, resulting in 288 matched patients (144 in each group). The primary outcomes were rates of complete AVM obliteration and functional outcomes (measured by the modified Rankin Scale (mRS)). Secondary outcomes included complication rates, mortality, hospital length of stay and postsurgical rupture. Results After matching, the complete obliteration rate was 97% with no significant difference between the microsurgery-only group and the preoperative embolization group (p=0.12). The proportion of patients with an mRS score of 0–2 at the last follow-up was similar in both groups (83% vs 84%; p=0.67). The median hospital stay was significantly longer for the embolisation group (9 days vs 7 days; p=0.017). Complication rates (24% vs 22%; p=0.57) and mortality rates (4.9% vs 2.1%; p=0.20) were comparable between the two groups. No significant differences were observed in postsurgical rupture, recurrence or retreatment rates. Conclusions In this large multicentre study, preoperative embolization did not significantly improve AVM obliteration rates, functional outcomes or reduce complications compared with microsurgery alone.

Background Arteriovenous malformations (AVMs) are uncommon cerebral lesions that can cause significant neurological complications. Surgical resection is the gold standard for treatment, but endovascular embolization and stereotactic radiosurgery (SRS) are viable alternatives. Objective To compare the outcomes of endovascular embolization versus SRS in the treatment of AVMs with Spetzler-Martin grades I–III. Methods This study combined retrospective data from 10 academic institutions in North America and Europe. Patients aged 1 to 90 years who underwent endovascular embolization or SRS for AVMs with Spetzler-Martin grades I–III between January 2010 and December 2023 were included. Results The study included 244 patients, including 84 who had endovascular embolization and 160 who had SRS. Before propensity score matching (PSM), complete obliteration at the last follow-up was achieved in 74.5% of the SRS group compared with 57.8% of the embolization group (OR=0.47; 95% CI 0.26 to 0.48; P=0.01). After propensity score matching, SRS still achieved significantly higher occlusion rates at last follow-up (78.9% vs 55.3%; OR=0.32; 95% CI 0.12 to 0.90; P=0.03). Hemorrhagic complications were higher in the embolization group than in the SRS group, although this difference did not reach statistical significance after PSM (13.2% vs 2.6%; OR=5.6; 95% CI 0.62 to 50.47; P=0.12). Similarly, re-treatment rate was higher in the embolization group (10.5% vs 5.3%; OR=2.11; 95% CI 0.36 to 12.31; P=0.40) compared with the SRS group. Conclusion Our findings indicate that SRS has a significantly higher obliteration rate at last follow-up compared with endovascular embolization. Also, SRS has a higher tendency for fewer hemorrhagic complications and lower re-treatment rate. Further prospective studies are needed.

BACKGROUND AND OBJECTIVES: Health care providers' exposure to global surgical disparities is limited in current nursing and/or medical school curricula. For instance, global health is often associated with infectious diseases or maternal health without acknowledging the growing need for surgical care in low- and middle-income countries (LMICs). We propose an international virtual hackathon based on neurosurgical patient cases in under-resourced settings as an educational tool to bring awareness to global surgical disparities and develop relationships among trainees in different countries. METHODS: Participants were recruited through email listservs, a social media campaign, and prize offerings. A 3-day virtual hackathon event was administered, which included workshops, mentorship, keynote panels, and pitch presentations to judges. Participants were presented with real patient cases and directed to solve a barrier to their care. Surveys assessed participants' backgrounds and event experience. The hackathon was executed through Zoom at Harvard Innovation Lab in Boston, MA, on March 25 to 27, 2022. Participants included medical students, with additional participants from business, engineering, or current health care workers. RESULTS: Three hundred seven applications were submitted for 100 spots. Participants included medical students, physicians, nurses, engineers, entrepreneurs, and undergraduates representing 25 countries and 82 cities. Fifty-one participants previously met a neurosurgeon, while 39 previously met a global health expert, with no difference between LMIC and high-income countries' respondents. Teams spent an average of 2.75 hours working with mentors, and 88% of postevent respondents said the event was “very” or “extremely conducive” to networking. Projects fell into 4 categories: access, language barriers, education and training, and resources. The winning team, which was interdisciplinary and international, developed an application that analyzes patient anatomy while performing physical therapy to facilitate remote care and clinical decision-making. CONCLUSION: An international virtual hackathon can be an educational tool to increase innovative ideas to address surgical disparities in LMICs and establish early collaborative relationships with medical trainees from different countries.

OBJECTIVE Borden-Shucart type I dural arteriovenous fistulas (dAVFs) lack cortical venous drainage and occasionally necessitate intervention depending on patient symptoms. Conversion is the rare transformation of a low-grade dAVF to a higher grade. Factors associated with increased risk of dAVF conversion to a higher grade are poorly understood. The authors hypothesized that partial treatment of type I dAVFs is an independent risk factor for conversion. METHODS The multicenter Consortium for Dural Arteriovenous Fistula Outcomes Research database was used to perform a retrospective analysis of all patients with type I dAVFs. RESULTS Three hundred fifty-eight (33.2%) of 1077 patients had type I dAVFs. Of those 358 patients, 206 received endovascular treatment and 131 were not treated. Two (2.2%) of 91 patients receiving partial endovascular treatment for a low-grade dAVF experienced conversion to a higher grade, 2 (1.5%) of 131 who were not treated experienced conversion, and none (0%) of 115 patients who received complete endovascular treatment experienced dAVF conversion. The majority of converted dAVFs localized to the transverse-sigmoid sinus and all received embolization as part of their treatment. CONCLUSIONS Partial treatment of type I dAVFs does not appear to be significantly associated with conversion to a higher grade.

ImportanceTesting new medical devices or procedures in terms of safety, effectiveness, and durability should follow the strictest methodological rigor before implementation.ObjectivesTo review and analyze studies investigating devices and procedures used in intracranial aneurysm (IA) treatment for methods and completeness of reporting and to compare the results of studies with positive, uncertain, and negative conclusions.Data SourcesEmbase, MEDLINE, Web of Science, and The Cochrane Central Register of Clinical Trials were searched for studies on IA treatment published between January 1, 1995, and the October 1, 2022. Grey literature was retrieved from Google Scholar.Study SelectionAll studies making any kind of claims of safety, effectiveness, or durability in the field of IA treatment were included.Data Extraction and SynthesisUsing a predefined data dictionary and analysis plan, variables ranging from patient and aneurysm characteristics to the results of treatment were extracted, as were details pertaining to study methods and completeness of reporting. Extraction was performed by 10 independent reviewers. A blinded academic neuro-linguist without involvement in IA research evaluated the conclusion of each study as either positive, uncertain, or negative. The study followed Preferring Reporting Items for Systematic Reviews and Meta-Analyses guidelines.Main Outcomes and MeasuresThe incidence of domain-specific outcomes between studies with positive, uncertain, or negative conclusions regarding safety, effectiveness, or durability were compared. The number of studies that provided a definition of safety, effectiveness, or durability and the incidence of incomplete reporting of domain-specific outcomes were evaluated.ResultsOverall, 12 954 studies were screened, and 1356 studies were included, comprising a total of 410 993 treated patients. There was no difference in the proportion of patients with poor outcome or in-hospital mortality between studies claiming a technique was safe, uncertain, or not safe. Similarly, there was no difference in the proportion of IAs completely occluded at last follow-up between studies claiming a technique was effective, uncertain, or noneffective. Less than 2% of studies provided any definition of safety, effectiveness, or durability, and only 1 of the 1356 studies provided a threshold under which the technique would be considered unsafe. Incomplete reporting was found in 546 reports (40%).Conclusions and RelevanceIn this systematic review and meta-analysis of IA treatment literature, studies claiming safety, effectiveness, or durability of IA treatment had methodological flaws and incomplete reporting of relevant outcomes supporting these claims.

Introduction: The long-term effects of interventional treatment (with surgery, stereotactic radiosurgery, or endovascular embolization) for unruptured brain arteriovenous malformations (uBAVM) are uncertain. We address this in a large multi-center international cohort study comparing risk of intracranial hemorrhage (ICH) in the treated and untreated course of uBAVM patients. Methods: We pooled individual patient data (n=3,291) from 10 cohorts and imputed missing data. Survival analysis was performed from time of uBAVM diagnosis to intracranial hemorrhage (ICH) using Cox models, stratified by cohort, censoring at death or last follow-up, and including BAVM interventional treatment as a time-varying covariate. We tested for an interaction of treatment with follow-up time, then estimated the association of interventional treatment with ICH, adjusting for propensity quintile. Individual treatment propensity scores were calculated using logistic regression with Spetzler-Martin grade, sex, diagnosis age and year, cohort, and presence of presenting symptoms (seizures, headaches, and/or deficits). Results: Median cohort age was 36 years, 48% were female, and 77% received ≥1 treatment modality for uBAVM during follow-up. 373 ICH occurred during 32,054 person-years of follow-up (median=6.6y), for an ICH rate of 1.16 per 100 P-Y. Overall, treatment was not associated with risk of ICH (HR=1.12, 95% CI=0.89-1.51, p=0.33). However, we observed a strong interaction between treatment and follow-up time (p<0.001): between 0-1 year, treatment was associated with higher risk of ICH (HR=3.48, 95% CI: 2.26-5.37, p<0.001); between 1-10 years, we found no association between treatment and risk of ICH (HR=1.02, 95% CI: 0.73-1.45, p=0.87); after 10 years, treatment was associated with a lower risk of ICH (HR=0.46, 95% CI: 0.30-0.70, p<0.001). Survival curves for untreated and treated courses crossed around 17 years. Conclusion: After accounting for treatment propensity for uBAVM, we found an initial increased risk of ICH in the treated relative to untreated course, which continually declined over time with survival curves crossing around 17 years. These results require confirmation in a randomized controlled trial of uBAVM with long-term follow-up.

BACKGROUND: Dural arteriovenous fistulas (dAVFs) located at craniocervical junction are extremely rare (1%-2% of intracranial/spinal dAVFs). Their angio-architectural complexity renders endovascular embolization to be challenging given multiple small feeders with risk of embolysate reflux into vertebral artery and limited transvenous access. The available literature discussing microsurgery for these lesions is limited to few case reports. OBJECTIVE: To report a multicenter experience assessing microsurgery safety/efficacy. METHODS: Prospectively maintained registries at 13 North American centers were queried to identify craniocervical junction dAVFs treated with microsurgery (2006-2021). RESULTS: Thirty-eight patients (median age 59.5 years, 44.7% female patients) were included. The most common presentation was subarachnoid/intracranial hemorrhage (47.4%) and myelopathy (36.8%) (92.1% of lesions Cognard type III-V). Direct meningeal branches from V3/4 vertebral artery segments supplied 84.2% of lesions. All lesions failed (n = 5, 13.2%) or were deemed inaccessible/unsafe to endovascular treatment. Far lateral craniotomy was the most used approach (94.7%). Intraoperative angiogram was performed in 39.5% of the cases, with angiographic cure in 94.7% of cases (median imaging follow-up of 9.2 months) and retreatment rate of 5.3%. Favorable last follow-up modified Rankin Scale of 0 to 2 was recorded in 81.6% of the patients with procedural complications of 2.6%. CONCLUSION: Craniocervical dAVFs represent rare entity of lesions presenting most commonly with hemorrhage or myelopathy because of venous congestion. Microsurgery using a far lateral approach provides robust exposure and visualization for these lesions and allows obliteration of the arterialized draining vein intradurally as close as possible to the fistula point. This approach was associated with a high rate of angiographic cure and favorable clinical outcomes.

OBJECTIVE Indication for surgery in brainstem cavernous malformations (BSCMs) is based on many case series, few comparative studies, and no randomized controlled trials. The objective of this study was to seek consensus about surgical management aspects of BSCM. METHODS A total of 29 experts were invited to participate in a multistep Delphi consensus process on the surgical treatment of BSCM. RESULTS Twenty-two (76%) of 29 experts participated in the consensus. Qualitative analysis (content analysis) of an initial open-ended question survey resulted in 99 statements regarding surgical treatment of BSCM. By using a multistep survey with 100% participation in each round, consensus was reached on 52 (53%) of 99 statements. These were grouped into 4 categories: 1) definitions and reporting standards (7/14, 50%); 2) general and patient-related aspects (11/16, 69%); 3) anatomical-, timing of surgery–, and BSCM-related aspects (22/37, 59%); and 4) clinical situation–based decision-making (12/32, 38%). Among other things, a consensus was reached for surgical timing, handling of associated developmental venous anomalies, handling of postoperative BSCM remnants, assessment of specific anatomical BSCM localizations, and treatment decisions in typical clinical BSCM scenarios. CONCLUSIONS A summary of typical clinical scenarios and a catalog of various BSCM- and patient-related aspects that influence the surgical treatment decision have been defined, rated, and interpreted.