Responses to ARUBA: a systematic review and critical analysis for the design of future arteriovenous malformation trials

Changes in inpatient brain arteriovenous malformation management in the United States following the ARUBA trial: analysis of an interrupted time series design

The November 2013 online publication of ARUBA, the first multi-institutional randomized controlled trial for unruptured brain arteriovenous malformations (AVMs), has sparked over 100 publications in protracted debates METHODS: This study sought to examine inpatient management patterns of brain AVMs from 2009 to 2016 and observe if changes in U.S. inpatient management were attributable to the ARUBA publication using interrupted time series of brain AVM studies from the National Inpatient Sample data 2009-2016. Outcomes of interest were use of embolization, surgery, combined embolization and microsurgery, radiotherapy, and observation during that admission. An interrupted time series design compared management trends before and after ARUBA. Segmented linear regression analysis tested for immediate and long-term impacts of ARUBA on management. RESULTS: Elective and asymptomatic patient admissions declined 2009-2016. In keeping with the ARUBA findings, observation for unruptured brain AVMs increased and microsurgery decreased. However, embolization, radiosurgery, and combined embolization and microsurgery also increased. For ruptured brain AVMs, treatment modality trends remained positive with even greater rates of observation, embolization, and combined embolization and microsurgery occurring after ARUBA (data on radiosurgery were scarce). None of the estimates for the change in trends were statistically significant. CONCLUSIONS: The publication of ARUBA was associated with a decrease in microsurgery and increase in observation for unruptured brain AVMs in the US. However, inpatient radiotherapy, embolization, and combined embolization and surgery also increased, suggesting trends moved counter to ARUBA's conclusions. This analysis suggested that ARUBA had a small impact as clinicians rejected ARUBA's findings in managing unruptured brain AVMs.

Medical management and surgery versus medical management alone for symptomatic cerebral cavernous malformation (CARE): a feasibility study and randomised, open, pragmatic, pilot phase trial

BACKGROUND

The highest priority uncertainty for people with symptomatic cerebral cavernous malformation is whether to have medical management and surgery or medical management alone. We conducted a pilot phase randomised controlled trial to assess the feasibility of addressing this uncertainty in a definitive trial.

METHODS

The CARE pilot trial was a prospective, randomised, open-label, assessor-blinded, parallel-group trial at neuroscience centres in the UK and Ireland. We aimed to recruit 60 people of any age, sex, and ethnicity who had mental capacity, were resident in the UK or Ireland, and had a symptomatic cerebral cavernous malformation. Computerised, web-based randomisation assigned participants (1:1) to medical management and surgery (neurosurgical resection or stereotactic radiosurgery) or medical management alone, stratified by the neurosurgeon's and participant's consensus about the intended type of surgery before randomisation. Assignment was open to investigators, participants, and carers, but not clinical outcome event adjudicators. Feasibility outcomes included site engagement, recruitment, choice of surgical management, retention, adherence, data quality, clinical outcome event rate, and protocol implementation. The primary clinical outcome was symptomatic intracranial haemorrhage or new persistent or progressive non-haemorrhagic focal neurological deficit due to cerebral cavernous malformation or surgery during at least 6 months of follow-up. We analysed data from all randomly assigned participants according to assigned management. This trial is registered with ISRCTN (ISRCTN41647111) and has been completed.

FINDINGS

Between Sept 27, 2021, and April 28, 2023, 28 (70%) of 40 sites took part, at which investigators screened 511 patients, of whom 322 (63%) were eligible, 202 were approached for recruitment, and 96 had collective uncertainty with their neurosurgeon about whether to have surgery for a symptomatic cerebral cavernous malformation. 72 (22%) of 322 eligible patients were randomly assigned (mean recruitment rate 0·2 [SD 0·25] participants per site per month) at a median of 287 (IQR 67-591) days since the most recent symptomatic presentation. Participants' median age was 50·6 (IQR 38·6-59·2) years, 68 (94%) of 72 participants were adults, 41 (57%) were female, 66 (92%) were White, 56 (78%) had a previous intracranial haemorrhage, and 28 (39%) had a previous epileptic seizure. The intended type of surgery before randomisation was neurosurgical resection for 19 (26%) of 72, stereotactic radiosurgery for 44 (61%), and no preference for nine (13%). Baseline clinical and imaging data were complete for all participants. 36 participants were randomly assigned to medical management and surgery (12 to neurosurgical resection and 24 to stereotactic radiosurgery) and 36 to medical management alone. Three (4%) of 72 participants withdrew, one was lost to follow-up, and one declined face-to-face follow-up, leaving 67 (93%) retained at 6-months' clinical follow-up. 61 (91%) of 67 participants with follow-up adhered to the assigned management strategy. The primary clinical outcome occurred in two (6%) of 33 participants randomly assigned to medical management and surgery (8·0%, 95% CI 2·0-32·1 per year) and in two (6%) of 34 participants randomly assigned to medical management alone (7·5%, 1·9-30·1 per year). Investigators reported no deaths, no serious adverse events, one protocol violation, and 61 protocol deviations.

INTERPRETATION

This pilot phase trial exceeded its recruitment target, but a definitive trial will require extensive international engagement.

FUNDING

National Institute for Health and Care Research.

The use and abuse of survival analysis and Kaplan-Meier curves in surgical trials

BACKGROUND

Survival analysis based on Cox regression and Kaplan-Meier curves, initially devised for oncology trials, have frequently been used in other contexts where fundamental statistical assumptions (such as a constant hazard ratio) are not satisfied. This is almost always the case in trials that compare surgery with medical management.

METHODS

We review a trial that compared extracranial-intracranial bypass surgery (EC-IC bypass) with medical management (MM) of patients with symptomatic occlusion of the carotid or middle cerebral artery, where it was claimed that surgery was of no benefit. We discuss a hypothetical study and review other neurovascular trials which have also used survival analysis to compare results.

RESULTS

The trial comparing EC-IC bypass and MM did not satisfy the fundamental proportional hazard assumption necessary for valid analyses. This was also the case for two prior EC-IC bypass trials, as well as for other landmark neurovascular studies, such as the trials comparing endarterectomy with MM for carotid stenoses, or for the trial that compared intervention and MM for unruptured brain arteriovenous malformations. While minor deviations may have little effect on large trials, it may be impossible to show the benefits of surgery when trial size is small and deviations large.

CONCLUSION

Survival analyses are inappropriate in RCTs comparing surgery with conservative management, unless survival is calculated after the postoperative period. Alternative ways to compare final clinical outcomes, using for example a fixed follow-up period, should be planned for preventive surgical trials that compare intervention with conservative management.

Natural history and clinical manifestation of Pediatric Brain Arteriovenous Malformations

Brain arteriovenous malformations (bAVMs) are aberrant arteriovenous shunts through a vascular nidus with no intervening capillary beds. They are one of the commonest causes of spontaneous intracranial haemorrhage in children and may be associated with significant morbidity and mortality in cases of rupture. Treatment strategies include microsurgical resection, endovascular embolisation, stereotactic radiosurgery, multimodality treatment with a combination thereof, and particularly in high-grade bAVMs, conservative management. Clinicians involved in treating bAVMs need to have familiarity with the natural history pertaining to bAVMs in terms of risk of rupture, risk factors elevating rupture risk as well as understanding the clinical manifestations of bAVMs. This invited review serves to provide a synthesis on natural history and clinical presentation of bAVMs with particular focus in children to inform decision-making pertaining to management.

Addressing barriers and identifying facilitators to support informed consent and recruitment in the Cavernous malformations A Randomised Effectiveness (CARE) pilot phase trial: insights from the integrated QuinteT recruitment intervention (QRI)

Background

It was anticipated that recruitment to the Cavernous malformations: A Randomised Effectiveness (CARE) pilot randomised trial would be challenging. The trial compared medical management and surgery (neurosurgical resection or stereotactic radiosurgery) with medical management alone, for people with symptomatic cerebral cavernous malformation (ISRCTN41647111). Previous trials comparing surgical and medical management for intracranial vascular malformations failed to recruit to target. A QuinteT Recruitment Intervention was integrated during trial accrual, September 2021-April 2023 inclusive, to improve informed consent and recruitment.

Methods

The QuinteT Recruitment Intervention combined iterative collection and analysis of quantitative data (28 trial site screening logs recording numbers/proportions screened, eligible, approached and randomised) and qualitative data (79 audio-recorded recruitment discussions, 19 interviews with healthcare professionals, 11 interviews with patients, 2 investigator workshops, and observations of study meetings, all subject to thematic, content or conversation analysis). We triangulated quantitative and qualitative data to identify barriers and facilitators to recruitment and how and why these arose. Working with the chief investigators and trial management group, we addressed barriers and facilitators with corresponding actions to improve informed consent and recruitment.

Findings

Barriers identified included how usual care practices made equipoise challenging, multi-disciplinary teams sometimes overrode recruiter equipoise and logistical issues rendered symptomatic cavernoma diagnosis and assessment for stereotactic radiosurgery challenging. Facilitators identified included the preparedness of some neurosurgeons' to offer surgery to people otherwise offered medical management alone, multi-disciplinary team equipoise, and effective information provision presenting participation as a solution to equipoise regarding management. Actions, before and during recruitment, to improve inclusivity of site screening, approach and effectiveness of information provision resulted in 72 participants recruited following a 5-month extension, exceeding the target of 60 participants.

Interpretation

QuinteT Recruitment Intervention insights revealed barriers and facilitators, enabling identification of remedial actions. Recruitment to a definitive trial would benefit from further training/support to encourage clinicians to be comfortable approaching patients to whom medical management is usually offered, and broadening the pool of neurosurgeons and multi-disciplinary team members prepared to offer surgery, particularly stereotactic radiosurgery.

Funding

National Institute for Health and Care Research.

Impact of tailored multimodal treatment for unruptured brain arteriovenous malformation: comparison with a randomized trial of unruptured brain arteriovenous malformations

PURPOSE

The first randomized controlled study on unruptured brain arteriovenous malformations (bAVM), the ARUBA trial, demonstrate the superiority of medical management; however, it failed to completely rule out the efficacy of therapeutic interventions due to several limitations. This study aimed to examine the outcomes of multimodal interventional treatment for bAVM in terms of safety and efficacy.

METHODS

We reviewed 226 consecutive patients with unruptured bAVM admitted to our institute between 2002 and 2022. Treatment methods were divided into medical management and therapeutic intervention, including microsurgery, stereotactic surgery, and endovascular intervention. First, the choice of therapeutic modalities was assessed in the pre-ARUBA (before February 2014) and post-ARUBA (after March 2014) eras. Second, the incidence of symptomatic stroke or death and functional prognosis with a modified Rankin scale (mRS) score of ≥2 at 5 years was compared between the medical management and therapeutic intervention.

RESULTS

In the pre- and post-ARUBA groups, 73% and 84% of patients underwent therapeutic interventions, respectively (p = 0.053). The rate of symptomatic stroke or death was lower in patients who underwent interventional therapies than in those who underwent medical management (9.7% vs. 22%, p = 0.022); however, the opposite was observed in the ARUBA trial (31% vs. 10%). The annual incidence of stroke or death was also lower in the interventional therapy group (4.3%/y vs. 1.8%/year, hazard ratio = 0.45, 95% confidence interval: 0.18-1.08, p = 0.032). The rate of mRS score of ≥2 after a 5-year follow-up was 18% and 6% in the medical treatment and intervention groups (p = 0.14).

CONCLUSIONS

The therapeutic intervention rate did not decrease, even after the publication of the ARUBA trial. The rate of stroke or death was lower in the intervention group, indicating that a tailored choice of multimodality is safe and effective for managing unruptured bAVM.

National reduction in cerebral arteriovenous malformation treatment correlated with increased rupture incidence

BACKGROUND

Recently, there has been a shift in management of unruptured cerebral arteriovenous malformations (AVMs) following studies suggesting that medical management alone was superior to interventional therapy.

OBJECTIVE

To evaluate the influence of contemporary AVM management on AVM rupture patterns in the United States.

METHODS

154 297 AVM admissions were identified between 2003 and 2017 in the National Inpatient Sample. Annual AVM intervention and rupture rates were computed and multivariable logistic regression assessed the likelihood of AVM intervention pre- and post-2014. Segmented regression identified significant change points and fitted segmented linear models for annual intervention and rupture rates. Correlation coefficients assessed the relationship between annual AVM intervention and rupture rates.

RESULTS

For unruptured AVMs, intervention likelihood and proportion decreased after 2014 (28.1% to 22.3%, p<0.0001; adjusted OR=0.857, 95% CI 0.751 to 0.977, p=0.02). Ruptured AVM admissions increased from 14.7% to 18.6% after 2014 (p<0.0001). Between 2003 and 2017, segmented linear regression identified one significant change point in intervention rate between 2014 and 2015. Average annual percent change for rupture incidence and intervention rate increased by 0.49% (p=0.0001) and decreased by 1.17% (p=0.0001), respectively. Annual AVM intervention rates were inversely correlated with annual AVM rupture incidence (Pearson coefficient=-0.82, p=0.0002). In 2017, the annual AVM rupture rate (20.6%) surpassed the annual AVM intervention rate (19.7%).

CONCLUSIONS

After 2014, the likelihood of intervention for unruptured AVMs decreased while the incidence of ruptured AVMs increased. These findings suggest that fewer unruptured AVM treatments may lead to increases in AVM rupture incidence.

State of the Art in the Role of Endovascular Embolization in the Management of Brain Arteriovenous Malformations-A Systematic Review

As a significant cause of intracerebral hemorrhages, seizures, and neurological decline, brain arteriovenous malformations (bAVMs) are a rare group of complex vascular lesions with devastating implications for patients' quality of life. Although the concerted effort of the scientific community has improved our understanding of bAVM biology, the exact mechanism continues to be elucidated. Furthermore, to this day, due to the high heterogeneity of bAVMs as well as the lack of objective data brought by the lack of evaluative and comparative studies, there is no clear consensus on the treatment of this life-threatening and dynamic disease. As a consequence, patients often fall short of obtaining the optimal treatment. Endovascular embolization is an inherent part of multidisciplinary bAVM management that can be used in various clinical scenarios, each with different objectives. Well-trained neuro-interventional centers are proficient at curing bAVMs that are smaller than 3 cm; are located superficially in noneloquent areas; and have fewer, larger, and less tortuous feeding arteries. The transvenous approach is an emerging effective and safe technique that potentially offers a chance to cure previously untreatable bAVMs. This review provides the state of the art in all aspects of endovascular embolization in the management of bAVMs.

Assessment of gamma knife radiosurgery for unruptured cerebral arterioveneus malformations based on multi-parameter radiomics of MRI

OBJECTIVE

The treatment of Gamma knife radiosurgery (GKS) for unruptured Arteriovenous Malformations (AVM) remains controversial. A safe, effective and non-invasive method to predict outcome seems attractive for GKS. The purpose of this study was to develop and validate a MRI based multi-parameter radiomics model predicting the outcome of GKS for unruptured AVM.

METHODS

Eighty-eight unruptured AVM patients who initial underwent GKS between January 2011 and December 2016 in our hospital were included in this retrospective study. Patients were divided into two groups named as favourable and unfavourable outcome, according to the clinical outcome. Favourable outcome was defined as obliteration without post-SRS hemorrhage or permanent radiation-induced changes (RIC). Multivariate logistic regression analysis was used to select appropriate clinical features and construct a clinical predicting model. In terms of radiomic model, manually segmentation and radiomics extracted were performed on each AVM lesions. Finally, 1684 radiomics features were extracted and Recursive Feature Elimination (RFE) method combined with Random forest classifier were used for feature selection and model construction. The performance of the radiomics model was evaluated by the area under the curve (AUC), accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). In addition, the favourable group was further divided into early and late respond subgroup according to the time of obliteration evaluated by 2 years. The selected features were further compared according the respond time.

RESULTS

The median duration of neuroimaging follow-up was 65 months, 56 patients showed favourable outcome and 17 patients were observed obliteration within 2 years. The radiomics model constructed by 12 selected features achieved significant higher AUC of 0.88 (95% confidence interval 0.87-0.90) than traditional scoring system for predicting AVM outcome. Two selected radiomics features named "Dependence Variance" and "firstorder-Skewness" were found significant difference between the patients with early or late-respond.

CONCLUSIONS

The results suggest that the radiomics features could be successfully used for the pretreatment prediction of outcome for GKS in unruptured AVMs, which is helpful for decision-making process on unruptured AVM patients.

Endovascular treatment of brain arteriovenous malformations: clinical outcomes of patients included in the registry of a pragmatic randomized trial

OBJECTIVE

The role of endovascular treatment in the management of patients with brain arteriovenous malformations (AVMs) remains uncertain. AVM embolization can be offered as stand-alone curative therapy or prior to surgery or stereotactic radiosurgery (SRS) (pre-embolization). The Treatment of Brain AVMs Study (TOBAS) is an all-inclusive pragmatic study that comprises two randomized trials and multiple registries.

METHODS

Results from the TOBAS curative and pre-embolization registries are reported. The primary outcome for this report is death or dependency (modified Rankin Scale [mRS] score > 2) at last follow-up. Secondary outcomes include angiographic results, perioperative serious adverse events (SAEs), and permanent treatment-related complications leading to an mRS score > 2.

RESULTS

From June 2014 to May 2021, 1010 patients were recruited in TOBAS. Embolization was chosen as the primary curative treatment for 116 patients and pre-embolization prior to surgery or SRS for 92 patients. Clinical and angiographic outcomes were available in 106 (91%) of 116 and 77 (84%) of 92 patients, respectively. In the curative embolization registry, 70% of AVMs were ruptured, and 62% were low-grade AVMs (Spetzler-Martin grade I or II), while the pre-embolization registry had 70% ruptured AVMs and 58% low-grade AVMs. The primary outcome of death or disability (mRS score > 2) occurred in 15 (14%, 95% CI 8%–22%) of the 106 patients in the curative embolization registry (4 [12%, 95% CI 5%–28%] of 32 unruptured AVMs and 11 [15%, 95% CI 8%–25%] of 74 ruptured AVMs) and 9 (12%, 95% CI 6%–21%) of the 77 patients in the pre-embolization registry (4 [17%, 95% CI 7%–37%] of 23 unruptured AVMs and 5 [9%, 95% CI 4%–20%] of 54 ruptured AVMs) at 2 years. Embolization alone was confirmed to occlude the AVM in 32 (30%, 95% CI 21%–40%) of the 106 curative attempts and in 9 (12%, 95% CI 6%–21%) of 77 patients in the pre-embolization registry. SAEs occurred in 28 of the 106 attempted curative patients (26%, 95% CI 18%–35%, including 21 new symptomatic hemorrhages [20%, 95% CI 13%–29%]). Five of the new hemorrhages were in previously unruptured AVMs (n = 32; 16%, 95% CI 5%–33%). Of the 77 pre-embolization patients, 18 had SAEs (23%, 95% CI 15%–34%), including 12 new symptomatic hemorrhages [16%, 95% CI 9%–26%]). Three of the hemorrhages were in previously unruptured AVMs (3/23; 13%, 95% CI 3%–34%).

CONCLUSIONS

Embolization as a curative treatment for brain AVMs was often incomplete. Hemorrhagic complications were frequent, even when the specified intent was pre-embolization before surgery or SRS. Because the role of endovascular treatment remains uncertain, it should preferably, when possible, be offered in the context of a randomized trial.

Surgical management outcomes of intracranial arteriovenous malformations after preoperative embolization: a systematic review and meta-analysis

OBJECTIVE

Preoperative embolization for brain arteriovenous malformations (AVMs) has been shown to mitigate morbidity for high-risk AVMs, chiefly by reducing lesional blood flow before resection. However, associated risks include postembolization AVM rupture, and the effect of preoperative embolization on outcome remains uncertain. We performed a meta-analysis of the literature on preoperative embolization for microsurgically treated AVMs.

METHODS

A systematic review and meta-analysis were conducted of all English-language publications reporting clinical outcomes after combined embolization and surgical resection for AVMs. Single- and 2-arm analyses were performed using random-effects modeling.

RESULTS

Thirty-six studies with 2108 patients were included in this analysis. Most patients (90.6%) who underwent embolization had at least a 50% obliteration of AVMs on posttreatment preoperative angiography, with a mean rate of obliteration of approximately 80% (range 28.8-100%). Among patients who had combined treatment, 3.4% (95% confidence interval [CI] 2.1-4.6%) experienced embolization-related hemorrhagic complications before surgery. Both treatment groups achieved excellent postsurgical complete resection rates (odds ratio [OR] 1.05; 95% CI 0.60-1.85). Neither the clinical outcome (OR 1.42; 95% CI 0.84-2.40) nor the total number of hemorrhagic complications (OR 1.84; 95% CI 0.88-3.85) was significantly different between the treatment groups.

CONCLUSIONS

In this meta-analysis, preoperative embolization appears to have substantially reduced the lesional volume with active AV shunting before AVM resection. Anecdotally, preoperative embolization facilitates safe and efficient resection; however, differences in outcomes were not significant. The decision to pursue preoperative embolization remains a nuanced decision based on individual lesion anatomy and treatment team experience.

Surgical treatment of brain arteriovenous malformations: clinical outcomes of patients included in the registry of a pragmatic randomized trial

OBJECTIVE

The Treatment of Brain Arteriovenous Malformations Study (TOBAS) is a pragmatic study that includes 2 randomized trials and registries of treated or conservatively managed patients. The authors report the results of the surgical registry.

METHODS

TOBAS patients are managed according to an algorithm that combines clinical judgment and randomized allocation. For patients considered for curative treatment, clinicians selected from surgery, endovascular therapy, or radiation therapy as the primary curative method, and whether observation was a reasonable alternative. When surgery was selected and observation was deemed unreasonable, the patient was not included in the randomized controlled trial but placed in the surgical registry. The primary outcome of the trial was mRS score > 2 at 10 years (at last follow-up for the current report). Secondary outcomes include angiographic results, perioperative serious adverse events, and permanent treatment-related complications leading to mRS score > 2.

RESULTS

From June 2014 to May 2021, 1010 patients were recruited at 30 TOBAS centers. Surgery was selected for 229/512 patients (44%) considered for curative treatment; 77 (34%) were included in the surgery versus observation randomized trial and 152 (66%) were placed in the surgical registry. Surgical registry patients had 124/152 (82%) ruptured and 28/152 (18%) unruptured arteriovenous malformations (AVMs), with the majority categorized as low-grade Spetzler-Martin grade I-II AVM (118/152 [78%]). Thirteen patients were excluded, leaving 139 patients for analysis. Embolization was performed prior to surgery in 78/139 (56%) patients. Surgical angiographic cure was obtained in 123/139 all-grade (89%, 95% CI 82%-93%) and 105/110 low-grade (95%, 95% CI 90%-98%) AVM patients. At the mean follow-up of 18.1 months, 16 patients (12%, 95% CI 7%-18%) had reached the primary safety outcome of mRS score > 2, including 11/16 who had a baseline mRS score ≥ 3 due to previous AVM rupture. Serious adverse events occurred in 29 patients (21%, 95% CI 15%-28%). Permanent treatment-related complications leading to mRS score > 2 occurred in 6/139 patients (4%, 95% CI 2%-9%), 5 (83%) of whom had complications due to preoperative embolization.

CONCLUSIONS

The surgical treatment of brain AVMs in the TOBAS registry was curative in 88% of patients. The participation of more patients, surgeons, and centers in randomized trials is needed to definitively establish the role of surgery in the treatment of unruptured brain AVMs. Clinical trial registration no.: NCT02098252 (ClinicalTrials.gov).

Interventional outcomes for patients eligible for entry into the ARUBA clinical trial: a systematic review and meta-analysis

OBJECTIVE

A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA) suggested that medical management afforded outcomes superior to those following intervention for unruptured arteriovenous malformations (AVMs), but its findings have been controversial. Subsequent studies of AVMs that would have met the eligibility requirements of ARUBA have supported intervention for the management of some cases. The present meta-analysis was conducted with the object of summarizing interventional outcomes for ARUBA-eligible patients reported in the literature.

METHODS

A systematic literature search (PubMed, Web of Science, Google Scholar) for AVM intervention studies that used inclusion criteria identical to those of ARUBA (age ≥ 18 years, no history of AVM hemorrhage, no prior intervention) was performed. The primary outcome was death or symptomatic stroke. Secondary outcomes included AVM obliteration, hemorrhage, death, and poor outcome (modified Rankin Scale score ≥ 2 at final follow-up). Bias assessment was performed with the Newcastle-Ottawa Scale, and the results were synthesized as pooled proportions.

RESULTS

Of the 343 articles identified through database searches, 13 studies met the inclusion criteria, yielding an overall study cohort of 1909 patients. The primary outcome occurred in 11.2% of patients (pooled = 11%, 95% CI 8%-13%). The rates of AVM obliteration, hemorrhage, poor outcome, and death were 72.7% (pooled = 78%, 95% CI 70%-85%), 8.4% (pooled = 8%, 95% CI 6%-11%), 9.9% (pooled = 10%, 95% CI 7%-13%), and 3.5% (pooled = 2%, 95% CI 1%-4%), respectively. Annualized primary outcome and hemorrhage risks were 1.85 (pooled = 2.05, 95% CI 1.31-2.94) and 1.34 (pooled = 1.41, 95% CI 0.83-2.13) per 100 patient-years, respectively.

CONCLUSIONS

Intervention for unruptured AVMs affords acceptable outcomes for appropriately selected patients. The risk of hemorrhage following intervention compared favorably to the natural history of unruptured AVMs. The included studies were retrospective and varied in treatment and AVM characteristics, thereby limiting the generalizability of their data. Future studies from prospective registries may clarify patient, nidus, and intervention selection criteria that will refine the challenging management of patients with unruptured AVMs.

Understanding burden of proof and equipoise in the design of pragmatic clinical trials: An example from a trial on brain arteriovenous malformations

BACKGROUND AND PURPOSE

The burden of proof principle is rarely discussed and poorly understood, but central to the proper design of pragmatic clinical trials. A better understanding of the principle could play an important role in the re-introduction of scientific methods within practice and in revising fundamental problems with the current research-care separation.

METHODS

We analyze the design of the ARUBA trial on the management of unruptured brain arteriovenous malformations. We also review how the concept of clinical equipoise was introduced to address a misconceived problem of research ethics.

RESULTS

The ARUBA trial hypothesis in favour of conservative management of brain arteriovenous malformations failed to take into account the fact that the burden of proof was on surgery, endovascular treatment or radiation therapy. Thus, results remained inconclusive and other trials are needed. The equipoise notion fails to take into account that the burden of proof is on unvalidated medical or surgical interventions, if we want to provide outcome-based medical care that patients can trust.

CONCLUSION

The burden of proof principle is essential to properly design pragmatic trials. This principle also explains why in certain circumstances optimal care is a randomized care trial.

Microsurgical Treatment of Deep and Eloquent AVMs

Over the past 30 years, the treatment of deep and eloquent arteriovenous malformations (AVMs) has moved away from microneurosurgical resection and towards medical management and the so-called minimally invasive techniques, such as endovascular embolization and radiosurgery. The Spetzler-Martin grading system (and subsequent modifications) has done much to aid in risk stratification for surgical intervention; however, the system does not predict the risk of hemorrhage nor risk from other interventions. In more recent years, the ARUBA trial has suggested that unruptured AVMs should be medically managed. In our experience, although these eloquent regions of the brain should be discussed with patients in assessing the risks and benefits of intervention, we believe each AVM should be assessed based on the characteristics of the patient and the angio-architecture of the AVM, in particular venous hypertension, which may guide us to treat even high-grade AVMs when we believe we can (and need to) to benefit the patient. Advances in imaging and intraoperative adjuncts have helped us in decision making, preoperative planning, and ensuring good outcomes for our patients. Here, we present several cases to illustrate our primary points that treating low-grade AVMs can be more difficult than treating high-grade ones, mismanagement of deep and eloquent AVMs at the behest of dogma can harm patients, and the treatment of any AVM should be tailored to the individual patient and that patient's lesion.

Multimodality Management in bAVM Surgery - Recent Experience from International Cerebrovascular Fellowship

Background:

Arteriovenous malformation (bAVM) presents maldevelopment of the brain’s vessels with a direct connection between cerebral arteries and veins. By current data, patients from Spetzler Ponce A (SP) are found to benefit from the treatment. Considering the outcome, most of SP C and some of the SP B are the most debatable.

Objective:

Arteriovenous malformation presents maldevelopment of the brain’s vessels with a consequent direct connection between cerebral arteries and veins. The annual risk of hemorrhage in adults is reported for 2-3 %. They usually present with unilateral headaches seizures and intracranial hemorrhage. By current data, patients from Spetzler Ponce A (SP) are found to benefit from the treatment. Considering the outcome, most of SP C and some of the SP B are the most debatable.

Methods:

The study included a cohort of bAVM patients referred to Fujita Health University Bantane Hotokukai Hospital, Nagoya, Aichi, Japan where the main author (AA) has completed an international cerebrovascular fellowship under the mentorship of Professor Yoko Kato. Japanese Stroke Guidelines (JSG) were used for the treatment decision. Patients were graded according to the Spetzler Ponce (SP) system. Considering American Heart Association criteria (AHA), embolization was used as a part of multimodal treatment. Intraoperative microscopic video tools included Indocyanine green ICG, FLOW 800 and dual image video angiography DIVA. Clinical outcomes were measured using Modified Ranking Score (mRs).

Results:

A total of eleven patients with brain bAVM were studied with a median age of 32 years [IQR = 22-52]. There were ten patients presented with supratentorial and a single patient with infratentorial AVM. Patients were graded according to the Spetzler Ponce (SP) system. There were eight patients in SP A (72,7%), one in group B (9 %) while the rest of them were in C (18 %). Two patients had associated aneurysms that required treatment. The median size of the AVM nidus was 3,50 cm [IQR= 2-5]. Deep venous drainage was found in six patients while three were located in eloquent zones. Clinical outcomes were considered good by mRs <2 in eight patients, seven from the surgically treated group (72,7 % respectively). Surgery median length time was 427, 5 minutes; [IQR =320 - 463] with complete AVM resection in all patients and no mortality recorded in this cohort with the median follow up of 39,5 months [IQR = 19-59].

Conclusion:

Ideal management of bAVM is still controversial. Those complex vascular lesions require multimodal treatment in a majority of cases in highly specialized centers. In SP A patients, surgery provides the best results with a positive outcome and a small number of complications. With the improvement of endovascular feeder occlusion SP B patients become prone to a more positive outcome. Nowadays, intraoperative microscopic tools such as FLOW 800, ICG and DIVA are irreplaceable while improving safety to deal with bAVM. For SP C patients, a combination of endovascular and stereotactic radiosurgery was found to be a good option in the present time.

Elective intervention for unruptured cranial arteriovenous malformations in relation to ARUBA trial: a National Inpatient Sample study

BACKGROUND

In 2014, A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA) concluded that medical management alone for cranial arteriovenous malformations (AVMs) had better clinical outcomes than interventional treatment. The impact of the ARUBA study on changes in the rates of intervention and outcomes is unknown. Thus, we investigated whether the conclusions from ARUBA may have influenced treatment modalities and outcomes of unruptured AVMs.

METHODS

The National Inpatient Sample (NIS) was queried between 2006 and 2018, for adult patients with an AVM who were admitted on an elective basis. Interventions included open, endovascular, and stereotactic surgeries. Join-point regression was used to assess differences in slopes of treatment rate for each modality before and after the time-point. Logistic regression was used to assess the odds of non-routine discharge and hemorrhage between the two time-points for each treatment modality. Linear regression was used to assess the mean length of stay (LOS) for each treatment modality between the two time-points.

RESULTS

A total of 40,285 elective admissions for AVMs were identified between 2006 and 2018. The rate of intervention was higher pre-ARUBA (n = 15,848; 63.8%) compared to post-ARUBA (n = 6985; 45.2%; difference in slope - 8.24%, p < 0.001). The rate of open surgery decreased, while endovascular and stereotactic surgeries remained the same, after the ARUBA trial time-point (difference in slopes - 8.24%, p < 0.001; - 1.74%, p = 0.055; 0.20%, p = 0.22, respectively). For admissions involving interventions, the odds of non-routine discharge were higher post-ARUBA (OR 1.24; p = 0.043); the odds of hemorrhage were lower post-ARUBA (OR 0.69; p = 0.025). There was no statistical difference in length of stay between the two time-points (p = 0.22).

CONCLUSION

The rate of intervention decreased, the rate of non-routine discharge increased, and rate of hemorrhage decreased post-ARUBA, suggesting that it may have influenced treatment practices for unruptured AVMs.

Presence of Vessel Wall Hyperintensity in Unruptured Arteriovenous Malformations on Vessel Wall Magnetic Resonance Imaging: Pilot Study of AVM Vessel Wall "Enhancement"

Purpose: High-resolution vessel wall magnetic resonance imaging (VW-MRI) could provide a way to identify high risk arteriovenous malformation (AVM) features. We present the first pilot study of clinically unruptured AVMs evaluated by high-resolution VW-MRI.

Methods: A retrospective review of clinically unruptured AVMs with VW-MRI between January 1, 2016 and December 31, 2018 was performed documenting the presence or absence of vessel wall “hyperintensity,” or enhancement, within the nidus as well as perivascular enhancement and evidence of old hemorrhage (EOOH). The extent of nidal vessel wall “hyperintensity” was approximated into five groups: 0, 1–25, 26–50, 51–75, and 76–100%.

Results: Of the nine cases, eight demonstrated at least some degree of vessel wall nidus “hyperintensity.” Of those eight cases, four demonstrated greater than 50% of the nidus with hyperintensity at the vessel wall, and three cases had perivascular enhancement adjacent to nidal vessels. Although none of the subjects had prior clinical hemorrhage/AVM rupture, of the six patients with available susceptibility weighted imaging to assess for remote hemorrhage, only two had subtle siderosis to suggest prior sub-clinical bleeds.

Conclusion: Vessel wall “enhancement” occurs in AVMs with no prior clinical rupture. Additional studies are needed to further investigate the implication of these findings.

Surgery for cerebral cavernous malformations: a systematic review and meta-analysis

BACKGROUND

We sought to quantify the risks of neurosurgical excision of cerebral cavernous malformations (CCMs) in a systematic review of cohort studies.

METHODS

We updated our previous systematic review by searching OVID Medline, OVID EMBASE, and the Cochrane Library from 1 January 2013 to 30 April 2019. The primary outcome was a composite of death attributed to CCM or surgery, non-fatal symptomatic intracerebral haemorrhage (ICH), or new or worsened persistent non-haemorrhagic focal neurological deficit (FND).

RESULTS

We included 70 cohorts, 67 reporting surgery alone, and three compared surgery to conservative management. A total of 5,089 patients (median age 36 years, 52% female) underwent surgery (total follow-up 19,404 patient-years). The annual rate of the composite outcome was 4.2% (95% CI 2.9 to 5.7; 46 cohorts; I² = 93%), which was higher in cohorts reporting exclusively brainstem CCM (6.0%, 95% CI 4.1-8.3; 25 cohorts, I² = 92%) versus predominantly supratentorial CCM (2.4%, 95% CI 1.3-3.8, 21 cohorts, I² = 86%, p_het = 0.001). The annual rate of the composite outcome was higher in cohorts with > 95% presenting with ICH (6.1%, 95% CI 4.2-8.4; 23 cohorts, I² = 93%) versus others (2.3%, 95% CI 1.2-3.7; 23 cohorts, I² = 83%, p_het = 0.001). The incidence of the composite outcome did not change over time in cohorts of exclusively brainstem CCM (p = 0.7) or predominantly supratentorial CCM (p = 0.5).

CONCLUSIONS

The risk of death, ICH, or FND after CCM excision is ~ 4%. This risk is higher for brainstem CCM and CCM that have caused ICH but has not changed over time.

TRIAL REGISTRATION

This systematic review was registered (PROSPERO CRD42019131246).

YouTube as a source of information for arteriovenous malformations: A content-quality and optimization analysis

AIM

YouTube (YT) is not only a source of entertainment but also, a popular source of medical knowledge. Our goal was to evaluate the quality of videos concerning arteriovenous malformations (AVM) available on YT.

MATERIALS AND METHODS

A YT search was conducted for the terms "Arteriovenous malformation", "AV malformations", "Intracranial AVM", "Cerebral AVM"," Brain AVM" and "Pial AVM." The first 70 videos for each search were evaluated and yielded 122 unique videos after the exclusion was applied. The videos were examined by two independent Raters using a validated quality criteria such as the Quality Criteria for Consumer Health Information (DISCERN), the Journal of the American Medical Association instrument (JAMA), and the Global Quality Score (GQS).

RESULTS

The mean DISCERN score was 30 out of 75 possible points, with an intraclass correlation coefficient for the absolute agreement of 0.98, indicating an excellent interrater reliability. Most videos were produced in the United States (51.6%) and were uploaded by educational channels. Videos had statistically higher DISCERN, JAMA, and GQS scores when they presented clear information, AVM symptoms, angioarchitecture, AVMs with concomitant aneurysms, risks of bleeding, Spetzler-Martin Grading, treatment information, treatment risks, treatment results, follow-up, diagrams, and a doctor as a speaker. Videos that featured animations observed higher popularity as indicated by the Video Power Index (VPI) and observed a higher DISCERN and GQS score. Videos with the overall highest VPI generated poor DISCERN scores.

CONCLUSIONS

YT does not provide high content quality medical information regarding AVMs and, in some cases, offer misleading information.

The 100 most cited articles in the endovascular treatment of brain arteriovenous malformations

BACKGROUND:

The literature base for endovascular treatment of brain arteriovenous malformations (BAVMs) has grown exponentially in recent decades. Bibliometric analysis has been used to identify impactful articles in other medical specialties. The aim of this citation analysis was to identify and characterize the top 100 most cited articles in the field of endovascular BAVM treatment.

METHODS:

The top-cited papers were identified by searching selected keywords (“endovascular treatment,” “interventional treatment,” “brain arteriovenous malformation,” “emboliz(s)ation”) on the Web of Science platform. The top 100 articles were ranked according to their number of citations. Each article was further evaluated to obtain predefined characteristics including citation(s) per year, year of publication, authorship, journal-title and impact factor, article topics, article type, and level of evidence.

RESULTS:

The top 100 most cited articles for endovascular BAVM treatment were published between 1960 and 2014. The total number of citations for these articles ranged from 56 to 471 (median 85.5). Most articles (76%) were published between 1990 and 2009 in three journals (56%), originated in the USA (52%) followed by France (16%). The most common topic related to embolization agents and the majority of articles constituted level IV or V evidence.

CONCLUSIONS:

This study provides a comprehensive overview of the most cited articles in the field of endovascular BAVM treatment. Our analysis recognizes key contributions from authors and institutions in the field and leads to a better understanding of the evidentiary framework for BAVM treatment.

Factors affecting the performance of brain arteriovenous malformation rupture prediction models

Background

In many cases, both the rupture rate of cerebral arteriovenous malformation (bAVM) in patients and the risk of endovascular or surgical treatment (when radiosurgery is not appropriate) are not low, it is important to assess the risk of rupture more cautiously before treatment. Based on the current high-risk predictors and clinical data, different sample sizes, sampling times and algorithms were used to build prediction models for the risk of hemorrhage in bAVM, and the accuracy and stability of the models were investigated. Our purpose was to remind researchers that there may be some pitfalls in developing similar prediction models.

Methods

The clinical data of 353 patients with bAVMs were collected. During the creation of prediction models for bAVM rupture, we changed the ratio of the training dataset to the test dataset, increased the number of sampling times, and built models for predicting bAVM rupture by the logistic regression (LR) algorithm and random forest (RF) algorithm. The area under the curve (AUC) was used to evaluate the predictive performances of those models.

Results

The performances of the prediction models built by both algorithms were not ideal (AUCs: 0.7 or less). The AUCs from the models built by the LR algorithm with different sample sizes were better than those built by the RF algorithm (0.70 vs 0.68, p < 0.001). The standard deviations (SDs) of the AUCs from both prediction models with different sample sizes displayed wide ranges (max range > 0.1).

Conclusions

Based on the current risk predictors, it may be difficult to build a stable and accurate prediction model for the hemorrhagic risk of bAVMs. Compared with sample size and algorithms, meaningful predictors are more important in establishing an accurate and stable prediction model.

Stereotactic Radiosurgery for Spetzler-Martin Grade I and II Arteriovenous Malformations: International Society of Stereotactic Radiosurgery (ISRS) Practice Guideline

BACKGROUND

No guidelines have been published regarding stereotactic radiosurgery (SRS) in the management of Spetzler-Martin grade I and II arteriovenous malformations (AVMs).

OBJECTIVE

To establish SRS practice guidelines for grade I-II AVMs on the basis of a systematic literature review.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-compliant search of Medline, Embase, and Scopus, 1986-2018, for publications reporting post-SRS outcomes in ≥10 grade I-II AVMs with a follow-up of ≥24 mo. Primary endpoints were obliteration and hemorrhage; secondary outcomes included Spetzler-Martin parameters, dosimetric variables, and “excellent” outcomes (defined as total obliteration without new post-SRS deficit).

RESULTS

Of 447 abstracts screened, 8 were included (n = 1, level 2 evidence; n = 7, level 4 evidence), representing 1102 AVMs, of which 836 (76%) were grade II. Obliteration was achieved in 884 (80%) at a median of 37 mo; 66 hemorrhages (6%) occurred during a median follow-up of 68 mo. Total obliteration without hemorrhage was achieved in 78%. Of 836 grade II AVMs, Spetzler-Martin parameters were reported in 680: 377 were eloquent brain and 178 had deep venous drainage, totaling 555/680 (82%) high-risk SRS-treated grade II AVMs.

CONCLUSION

The literature regarding SRS for grade I-II AVM is low quality, limiting interpretation. Cautiously, we observed that SRS appears to be a safe, effective treatment for grade I-II AVM and may be considered a front-line treatment, particularly for lesions in deep or eloquent locations. Preceding publications may be influenced by selection bias, with favorable AVMs undergoing resection, whereas those at increased risk of complications and nonobliteration are disproportionately referred for SRS.

Radiosurgery for unruptured brain arteriovenous malformations in the pre-ARUBA era: long-term obliteration rate, risk of hemorrhage and functional outcomes

The management of non-hemorrhagic arteriovenous malformations (AVMs) remains a subject of debate, even more since the ARUBA trial. Here, we report the obliteration rate, the risk of hemorrhage and the functional outcomes after Gamma Knife radiosurgery (GKRS) as first-line treatment for non-hemorrhagic AVMs treated before the ARUBA publication, in a reference university center with multimodal AVM treatments available. We retrospectively analyzed data from a continuous series of 172 patients harboring unruptured AVMs treated by GKRS as first-line treatment in our Lille University Hospital, France, between April 2004 and December 2013. The primary outcome was obliteration rate. Secondary outcomes were the hemorrhage rate, the modified Rankin Scale (mRS), morbidity and epilepsy control at last follow-up. The minimal follow-up period was of 3 years. Median age at presentation was 40 years (IQR 28; 51). Median follow-up was 8.8 years (IQR 6.8; 11.3). Median target volume was 1.9 cm³ (IQR 0.8–3.3 cm³), median Spetzler-Martin grade: 2 (IQR 1–2), median Pollock-Flickinger score: 1.07 (IQR 0.82–2.94), median Virginia score: 1 (IQR 1–2). Median treatment dose was 24 Gy at 50% isodose line. Twenty-three patients underwent a second GKRS after a median time of 58 months after first GKRS. The overall obliteration rate was of 76%, based primarily on cerebral angiography and/or rarely only upon MRI. Hemorrhage during the post-treatment follow-up was reported in 18 (10%) patients (annual risk of 1.1%). Transient post-GKRS morbidity was reported in 14 cases (8%) and persistent neurological deficit in 8 (4.6%) of patients. At last follow-up, 86% of patients had a mRS ≤ 1. Concerning patients with pretherapeutic epilepsy, 84.6% of them were seizure-free at last follow-up. GKRS as first-line therapeutic option for unruptured cerebral AVMs achieves high obliteration rates (76%) while maintaining a high-level patient’s autonomy. All hemorrhagic events occurred during the first 4 years after the initial GKRS. In cases with epilepsy, there was 84.6% seizure free at last follow-up. Permanent morbidity was reported in only 4.6%.

COVID-19 Pandemic and Its Impact on Neurosurgery Practice in Malaysia: Academic Insights, Clinical Experience and Protocols from March till August 2020

The newly discovered coronavirus disease 2019 (COVID-19) is an infectious disease introduced to humans for the first time. Following the pandemic of COVID-19, there is a major shift of practices among surgical departments in response to an unprecedented surge in reducing the transmission of disease. With pooling and outsourcing of more health care workers to emergency rooms, public health care services and medical services, further in-hospital resources are prioritised to those in need. It is imperative to balance the requirements of caring for COVID-19 patients with imminent risk of delay to others who need care. As Malaysia now approaches the recovery phase following the pandemic, the crisis impacted significantly on neurosurgical services throughout the country. Various emergency measures taken at the height of the crisis may remain as the new normal in the provision of neurosurgical services and practices in Malaysia. The crisis has certainly put a strain on the effective delivery of services and as we approach the recovery era, what may have been a strain may prove to be a silver lining in neurosurgical services in Malaysia. The following details are various measures put in place as the new operational protocols for neurosurgical services in Malaysia.

Arteriovenous malformation presenting with epilepsy: a multimodal approach to diagnosis and treatment

Arteriovenous malformation (AVM) presenting with epilepsy significantly impacts patient quality of life, and it should be considered very much a seizure disorder. Although hemorrhage prevention is the primary treatment aim of AVM surgery, seizure control should also be at the forefront of therapeutic management. Several hemodynamic and morphological characteristics of AVM have been identified to be associated with seizure presentation. This includes increased AVM flow, presence of long pial draining vein, venous outflow obstruction, and frontotemporal location, among other aspects. With the advent of high-throughput image processing and quantification methods, new radiographic attributes of AVM-related epilepsy have been identified. With respect to therapy, several treatment approaches are available, including conservative management or interventional modalities; this includes microsurgery, radiosurgery, and embolization or a combination thereof. Many studies, especially in the domain of microsurgery and radiosurgery, evaluate both techniques with respect to seizure outcomes. The advantage of microsurgery lies in superior AVM obliteration rates and swift seizure response. In addition, by incorporating electrophysiological monitoring during AVM resection, adjacent or even remote epileptogenic foci can be identified, leading to extended lesionectomy and improved seizure control. Radiosurgery, despite resulting in reduced AVM obliteration and prolonged time to seizure freedom, avoids the risks of surgery altogether and may provide seizure control through various antiepileptic mechanisms. Embolization continues to be used as an adjuvant for both microsurgery and radiosurgery. In this study, the authors review the latest imaging techniques in characterizing AVM-related epilepsy, in addition to reviewing each treatment modality.

More II It than Meets the Eye: Outcomes After Single-Fraction Stereotactic Radiosurgery in a Case Series of Low-Grade Arteriovenous Malformations

BACKGROUND

Surgical resection is typically cited as the optimal treatment of patients with Spetzler-Martin Grade I-II arteriovenous malformation (AVM).

OBJECTIVE

To report our experience with single-fraction stereotactic radiosurgery (SRS) for Spetzler-Martin Grade I-II AVM.

METHODS

A prospectively maintained registry was reviewed for patients with nonsyndromic Spetzler-Martin Grade I-II AVM having SRS from 1990 to 2011. Patients with <24 mo of follow-up or prior radiotherapy/SRS were excluded, resulting in a study population of 173 patients. Actuarial analysis was performed using the Kaplan-Meier method, and Cox proportional hazards modeling was performed with excellent outcomes (obliteration without new deficits) as the dependent variable.

RESULTS

Median post-SRS follow-up was 68 mo (range, 24-275). AVM obliteration was achieved in 132 (76%) after initial SRS. Eleven additional patients achieved obliteration after repeat SRS for an overall obliteration rate of 83%. The rate of obliteration was 60% at 4 yr and 78% at 8 yr. Post-SRS hemorrhage occurred in 7 patients (4%), resulting in 3 minor deficits (2%) and 1 death (<1%). Radiation-induced complications occurred in 5 patients (3%), resulting in minor deficits only. One hundred and thirty-seven patients (79%) had excellent outcomes at last follow-up.

CONCLUSION

SRS is a safe and effective treatment for patients with Spetzler-Martin Grade I-II AVM. Selection bias is likely a contributing factor to explain the superior outcomes generally noted in reported series of microsurgery for patients with low grade AVM.

Results of Surgery for Low-Grade Brain Arteriovenous Malformation Resection by Early Career Neurosurgeons: An Observational Study

BACKGROUND

For sustainability of arteriovenous malformation (AVM) surgery, results from early career cerebrovascular neurosurgeons (ECCNs) must be acceptably safe.

OBJECTIVE

To determine whether ECCNs performance of Spetzler-Ponce Class A AVM (SPC A) resection can be acceptably safe.

METHODS

ECCNs completing a cerebrovascular fellowship (2004-2015) with the last author were included. Inclusion of the ECCN cases occurred if they: had a prospective database of all AVM cases since commencing independent practice; were the primary surgeon on SPC A; and had made the significant management decisions. All SPC A surgical cases from the beginning of the ECCN's independent surgical practice to a maximum of 8 yr were included. An adverse outcome was considered a complication of surgery leading to a new permanent neurological deficit with a last modified Rankin Scale score >1. A cumulative summation (Cusum) plot examined the performance of each surgery. The highest acceptable level of adverse outcomes for the Cusum was 3.3%, derived from the upper 95% confidence interval of the last author's reported series.

RESULTS

Six ECCNs contributed 110 cases for analysis. The median number of SPC A cases operated by each ECCN was 16.5 (range 4-40). Preoperative embolization was performed in 5 (4.5%). The incidence of adverse outcomes was 1.8% (95% confidence interval: <0.01%-6.8%). At no point during the accumulated series did the combined cohort become unacceptable by the Cusum plot.

CONCLUSION

ECCNs with appropriate training appointed to large-volume cerebrovascular centers can achieve results for surgery for SPC A that are not appreciably worse than those published from high-volume neurosurgeons.

Expert Consensus on the Management of Brain Arteriovenous Malformations

Brain arteriovenous malformations (bAVMs) are complex, heterogeneous, and uncommon intracranial lesions. They can be treated by one or a combination of the following treatment modalities, namely embolization, radiosurgery, or microsurgical resection. In Spetzler-Martin Grade 4 and 5 arteriovenous malformations (AVMs), conservative management may be the best option. A group of experts in the management of AVMs of different disciplines gathered in January 2019 in Hanoi to compile the “Expert Consensus on the Management of Brain Arteriovenous Malformations”.

Gamma Knife Radiosurgery For Brain Vascular Malformations: Current Evidence And Future Tasks

Gamma Knife radiosurgery (GKRS) has long been used for treating brain vascular malformations, including arteriovenous malformations (AVMs), dural arteriovenous fistulas (DAVFs), and cavernous malformations (CMs). Herein, current evidence and controversies regarding the role of stereotactic radiosurgery for vascular malformations are described. 1) It has already been established that GKRS achieves 70–85% obliteration rates after a 3–5-year latency period for small to medium-sized AVMs. However, late radiation-induced adverse events (RAEs) including cyst formation, encapsulated hematoma, and tumorigenesis have recently been recognized, and the associated risks, clinical courses, and outcomes are under investigation. SRS-based therapeutic strategies for relatively large AVMs, including staged GKRS and a combination of GKRS and embolization, continue to be developed, though their advantages and disadvantages warrant further investigation. The role of GKRS in managing unruptured AVMs remains controversial since a prospective trial showed no benefit of treatment, necessitating further consideration of this issue. 2) Regarding DAVFs, GKRS achieves 41–90% obliteration rates at the second post-GKRS year with a hemorrhage rate below 5%. Debate continues as to whether GKRS might serve as a first-line solo therapeutic modality given its latency period. Although the post-GKRS outcomes are thought to differ among lesion locations, further outcome analyses regarding DAVF locations are required. 3) GKRS is generally accepted as an alternative for small or medium-sized CMs in which surgery is considered to be too risky. The reported hemorrhage rates ranged from 0.5–5% after GKRS. Higher dose treatments (>15 Gy) were performed during the learning curve, while, with the current standard treatment, a dose range of 12–15 Gy is generally selected, and has resulted in acceptable complication rates (< 5%). Nevertheless, further elucidation of long-term outcomes is essential.

Presence of direct vertebrobasilar perforator feeders in posterior fossa arteriovenous malformations and association with poor outcomes after endovascular treatment

OBJECTIVE

Treatment of posterior fossa arteriovenous malformations (PFAVMs) remains controversial as it is always challenging and may lead to major complications. Nonetheless, these lesions are more likely to bleed and generate poorer outcomes than other brain AVMs. The aim of this study was to evaluate the effect of endovascular treatment on long-term outcomes and identify the patient subgroups that might benefit from endovascular treatment.

METHODS

The authors performed a retrospective analysis of all consecutive cases of PFAVM managed at the Fondation Rothschild Hospital between 1995 and 2018. Clinical, imaging, and treatment data were prospectively gathered; these data were analyzed with respect to long-term outcomes.

RESULTS

Among the 1311 patients with brain AVMs, 114 (8.7%) had a PFAVM, and 88 (77.2%) of these patients had a history of bleeding. Of the 114 PFAVMs, 101 (88.6%) were treated (83 ruptured and 18 unruptured). The mean duration of follow-up was 47.6 months (range 0-240 months). Good neurological outcome at last follow-up was achieved in 79 cases (78.2%). Follow-up angiography showed obliteration of the PFAVM in 68.3% of treated cases. The presence of direct vertebrobasilar perforator feeders was associated with neurological deterioration (OR 5.63, 95% CI 11.15-30.76) and a lower obliteration rate (OR 15.69, 95% CI 2.52-304.03) after endovascular treatment. Other predictors of neurological deterioration and obliteration rate were consistent with the Spetzler-Martin grading system.

CONCLUSIONS

Advances in endovascular techniques have enabled higher obliteration rates in the treatment of PFAVMs, but complication rates are still high. Subgroups of patients who might benefit from treatment must be carefully selected and the presence of direct vertebrobasilar perforator feeders must call into question the indication for endovascular treatment.

Multimodal cerebral arteriovenous malformation treatment: a 12-year experience and comparison of key outcomes to ARUBA

OBJECTIVE

Curative treatment of unruptured brain arteriovenous malformations (AVMs) remains controversial after the only randomized controlled trial, A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA), was halted prematurely because interim analysis revealed superiority of the medical management group. In contrast, meta-analyses of retrospective cohorts suggest that intervention is much safer than was found in ARUBA.

METHODS

The authors retrospectively analyzed 318 consecutive adult patients with brain AVMs treated at their institution with embolization, surgery, and/or proton beam radiosurgery. Analysis was performed in 142 ARUBA-eligible patients (baseline modified Rankin Scale [mRS] score 0-1, no history of hemorrhage), and results were compared to primary and secondary outcomes from ARUBA, as well as to natural history cohorts.

RESULTS

The annualized stroke rate (hemorrhagic or ischemic) in this cohort was 1.8%, 4.9% in the first 12 months and 0.8% after the first 12 months, which was lower than in natural history studies and the ARUBA medical management arm (p = 0.001). The primary ARUBA endpoint of symptomatic stroke was reached in 13 patients (9.2%), which compares favorably to the ARUBA intervention arm (39.6%, p = 0.0001) and is similar to the ARUBA medical management arm (9.2%, p = 1.0). The secondary ARUBA endpoint (mRS score ≥ 2 at 5 years of follow-up) was reached in 14.3% of patients, compared to 40.5% in the ARUBA intervention arm (p = 0.002) and 16.7% in the ARUBA medical management arm (p = 0.6).

CONCLUSIONS

This multimodal approach to the selection and treatment of patients with brain AVMs yields good clinical outcomes with key safety endpoints (stroke, death, and mRS score 0-1) better than the ARUBA intervention arm and similar to the ARUBA medical arm at 5 years of follow-up. Results compare favorably to natural history cohorts at longer follow-up times. This suggests that tertiary care centers with integrated programs, expertise in patient selection, and individualized treatment approaches may allow for better clinical outcomes than reported in ARUBA. It supports current registry studies and merits consideration of future randomized controlled trials in patients with brain AVMs.

Updates in arteriovenous malformation management: the post-ARUBA era

Brain arteriovenous malformations (AVMs) are complex and heterogeneous lesions that can rupture, causing significant morbidity and mortality. While ruptured lesions are usually treated, the management of unruptured AVMs remains unclear. A Randomized trial of Unruptured Brain Arteriovenous Malformations (ARUBA) was the first trial conducted to compare the effects of medical and interventional therapy. Although it concluded that medical therapy was superior in preventing stroke and death over a follow-up period of 33 months, the findings were met with intense criticism regarding several aspects of study design, progression, and analysis/conclusion. Namely, the increased use of stand-alone embolisation relative to microsurgery in a cohort with predominantly low-grade lesions combined with a short follow-up period amplified treatment risk. Subsequently, several observational studies were conducted on ARUBA-eligible patients to investigate the safety and efficacy of microsurgery, radiosurgery, and endovascular embolisation over longer follow-up periods. These reports showed that favourable safety profiles and cure rates can be achieved with appropriate patient selection and judicious use of different treatment modalities in multidisciplinary centres. Since large prospective randomised trials on AVMs may not be feasible, it is important to make use of practice-based data beyond the flawed ARUBA study to optimise patients' lifetime outcomes.

Periprocedural intracranial hemorrhage after embolization of cerebral arteriovenous malformations: a meta-analysis

OBJECTIVE

The primary goal of the treatment of cerebral arteriovenous malformations (AVMs) is angiographic occlusion to eliminate future hemorrhage risk. Although multimodal treatment is increasingly used for AVMs, periprocedural hemorrhage after transarterial embolization is a potential endovascular complication that is only partially understood and merits quantification.

METHODS

Searching the period between 1990 and 2019, the authors of this meta-analysis queried the PubMed and Embase databases for studies reporting periprocedural hemorrhage (within 30 days) after liquid embolization (using cyanoacrylate or ethylene vinyl alcohol copolymer) of AVMs. Random effects meta-analysis was used to evaluate the pooled rate of flow-related hemorrhage (those attributed to alterations in AVM dynamics), technical hemorrhage (those related to procedural complications), and total hemorrhage. Meta-regression was used to analyze the study-level predictors of hemorrhage, including patient age, Spetzler-Martin grade, hemorrhagic presentation, embolysate used, intent of treatment (adjuvant vs curative), associated aneurysms, endovascular angiographic obliteration, year of study publication, and years the procedures were performed.

RESULTS

A total of 98 studies with 8009 patients were included in this analysis, and the mean number of embolization sessions per patient was 1.9. The pooled flow-related and total periprocedural hemorrhage rates were 2.0% (95% CI 1.5%-2.4%) and 2.6% (95% CI 2.1%-3.0%) per procedure and 3.4% (95% CI 2.6%-4.2%) and 4.8% (95% CI 4.0%-5.6%) per patient, respectively. The mortality and morbidity rates associated with hemorrhage were 14.6% and 45.1%, respectively. Subgroup analyses revealed a pooled total hemorrhage rate per procedure of 1.8% (95% CI 1.0%-2.5%) for adjuvant (surgery or radiosurgery) and 4.6% (95% CI 2.8%-6.4%) for curative intent. The treatment of aneurysms (p = 0.04) and larger patient populations (p < 0.001) were significant predictors of a lower hemorrhage rate, whereas curative intent (p = 0.04), angiographic obliteration achieved endovascularly (p = 0.003), and a greater number of embolization sessions (p = 0.03) were significant predictors of a higher hemorrhage rate. There were no significant differences in periprocedural hemorrhage rates according to the years evaluated or the embolysate utilized.

CONCLUSIONS

In this study-level meta-analysis, periprocedural hemorrhage was seen after 2.6% of transarterial embolization procedures for cerebral AVMs. The adjuvant use of endovascular embolization, including in the treatment of associated aneurysms and in the presurgical or preradiosurgical setting, was a study-level predictor of significantly lower hemorrhage rates, whereas more aggressive embolization involving curative intent and endovascular angiographic obliteration was a predictor of a significantly higher total hemorrhage rate.

Interventions for treating brain arteriovenous malformations in adults

BACKGROUND

Brain arteriovenous malformations (AVMs) are the single most common cause of intracerebral haemorrhage in young adults. Brain AVMs also cause seizure(s) and focal neurological deficits (in the absence of haemorrhage, migraine or an epileptic seizure); approximately one-fifth are incidental discoveries. Various interventions are used in an attempt to eradicate brain AVMs: neurosurgical excision, stereotactic radiosurgery, endovascular embolization, and staged combinations of these interventions. This is an update of a Cochrane Review first published in 2006, and last updated in 2009.

OBJECTIVES

To determine the effectiveness and safety of the different interventions, alone or in combination, for treating brain AVMs in adults compared against either each other, or conservative management, in randomized controlled trials (RCTs).

SEARCH METHODS

The Cochrane Stroke Group Information Specialist searched the Cochrane Stroke Group Trials Register (last searched 7 January 2019), the Cochrane Central Register of Controlled Trials (CENTRAL; 2019, Issue 1) in the Cochrane Library, MEDLINE Ovid (1980 to 14 January 2019), and Embase OVID (1980 to 14 January 2019). We searched international registers of clinical trials, the contents pages of relevant journals, and bibliographies of relevant articles (November 2009). We also contacted manufacturers of interventional treatments for brain AVMs (March 2005).

SELECTION CRITERIA

We sought RCTs of any intervention for brain AVMs (used alone or in combination), compared against each other or against conservative management, with relevant clinical outcome measures.

DATA COLLECTION AND ANALYSIS

One author screened the results of the updated searches for potentially eligible RCTs for this updated review. Both authors independently read the potentially eligible RCTs in full and confirmed their inclusion according to the inclusion criteria. We resolved disagreement by discussion. We assessed the risk of bias in included studies and applied GRADE.

MAIN RESULTS

We included one trial with 226 participants: A Randomized trial of Unruptured Brain Arteriovenous Malformations (ARUBA), comparing intervention versus conservative management for unruptured brain AVMs (that had never bled). The quality of evidence was moderate because we found just one trial that was at low risk of bias other than a high risk of performance bias due to participants and treating physicians not being blinded to allocated treatment. Data on functional outcome and death at a follow-up of 12 months were provided for 218 (96%) of the participants in ARUBA. In this randomized controlled trial (RCT), intervention compared to conservative management increased death or dependency (modified Rankin Scale score ≥ 2, risk ratio (RR) 2.53, 95% confidence interval (CI) 1.28 to 4.98; 1 trial, 226 participants; moderate-quality evidence) and the proportion of participants with symptomatic intracranial haemorrhage (RR 6.75, 95% CI 2.07 to 21.96; 1 trial, 226 participants; moderate-quality evidence), but there was no difference in the frequency of epileptic seizures (RR 1.14, 95% CI 0.63 to 2.06; 1 trial, 226 participants; moderate-quality evidence). Three RCTs are ongoing.

AUTHORS' CONCLUSIONS

We found moderate-quality evidence from one RCT including adults with unruptured brain AVMs that conservative management was superior to intervention with respect to functional outcome and symptomatic intracranial haemorrhage over one year after randomization. More RCTs will help to confirm or refute these findings.

R2eD AVM Score

Background and Purpose- The management of unruptured brain arteriovenous malformations remains unclear. Using a large cohort to determine risk factors predictive of hemorrhagic presentation of arteriovenous malformations, this study aims to develop a predictive tool that could guide hemorrhage risk stratification. Methods- A database of 789 arteriovenous malformation patients presenting to our institution between 1990 and 2017 was used. A hold-out method of model validation was used, whereby the data was randomly split in half into training and validation data sets. Factors significant at the univariable level in the training data set were used to construct a model based on multivariable logistic regression. Model performance was assessed using receiver operating curves on the training, validation, and complete data sets. The predictors and the complete data set were then used to derive a risk prediction formula and a practical scoring system, where every risk factor was worth 1 point except race, which was worth 2 points (total score varies from 0 to 6). The factors are summarized by R₂eD arteriovenous malformation (acronym: R₂eD AVM). Results- In 755 patients with complete data, 272 (36%) presented with hemorrhage. From the training data set, a model was derived containing the following risk factors: nonwhite race (odds ratio [OR]=1.8; P=0.02), small nidus size (OR=1.47; P=0.14), deep location (OR=2.3; P<0.01), single arterial feeder (OR=2.24; P<0.01), and exclusive deep venous drainage (OR=2.07; P=0.02). Area under the curve from receiver operating curve analysis was 0.702, 0.698, and 0.685 for the training, validation, and complete data sets, respectively. In the entire study population, the predicted probability of hemorrhagic presentation increased in a stepwise manner from 16% for patients with no risk factors (score of 0) to 78% for patients having all the risk factors (score of 6). Conclusions- The final model derived from this study can be used as a predictive tool that supplements clinical judgment and aids in patient counseling.

Standardized Evaluation of Cerebral Arteriovenous Malformations Using Flow Distribution Network Graphs and Dual-venc 4D Flow MRI

BACKGROUND

Cerebral arteriovenous malformations (AVMs) are pathological connections between arteries and veins. Dual-venc 4D flow MRI, an extended 4D flow MRI method with improved velocity dynamic range, provides time-resolved 3D cerebral hemodynamics.

PURPOSE

To optimize dual-venc 4D flow imaging parameters for AVM; to assess the relationship between spatial resolution, acceleration, and flow quantification accuracy; and to introduce and apply the flow distribution network graph (FDNG) paradigm for storing and analyzing complex neurovascular 4D flow data.

STUDY TYPE

Retrospective cohort study.

SUBJECTS/PHANTOM

Scans were performed in a specialized flow phantom: 26 healthy subjects (age 41 ± 17 years) and five AVM patients (age 27-68 years).

FIELD STRENGTH/SEQUENCE

Dual-venc 4D flow with varying spatial resolution and acceleration factors were performed at 3T field strength.

ASSESSMENT

Quantification accuracy was assessed in vitro by direct comparison to measured flow. FDNGs were used to quantify and compare flow, peak velocity (PV), and pulsatility index (PI) between healthy controls with various Circle of Willis (CoW) anatomy and AVM patients.

STATISTICAL TESTS

In vitro measurements were compared to ground truth with Student's t-test. In vivo groups were compared with Wilcoxon rank-sum test and Kruskal-Wallis test.

RESULTS

Flow was overestimated in all in vitro experiments, by an average 7.1 ± 1.4% for all measurement conditions. Error in flow measurement was significantly correlated with number of voxels across the channel (P = 3.11 × 10^-28 ) but not with acceleration factor (P = 0.74). For the venous-arterial PV and PI ratios, a significant difference was found between AVM nidal and extranidal circulation (P = 0.008 and 0.05, respectively), and between AVM nidal and healthy control circulation (P = 0.005 and 0.003, respectively).

DATA CONCLUSION

Dual-venc 4D flow MRI and standardized FDNG analysis might be feasible in clinical applications. Venous-arterial ratios of PV and PI are proposed as network-based biomarkers characterizing AVM nidal hemodynamics.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;50:1718-1730.

Endovascular Treatment for Low-Grade (Spetzler-Martin I-II) Brain Arteriovenous Malformations

BACKGROUND AND PURPOSE

Surgical resection is usually considered as the first-line curative strategy for low-grade (Spetzler-Martin grade I-II) brain arteriovenous malformations because it has a high cure rate and low complications. The role of endovascular treatment remains to be clarified in this indication, especially after A Randomized Trial of Unruptured Brain Arteriovenous Malformations. Our objective was to assess the safety and efficacy of first-line endovascular treatment in low-grade brain arteriovenous malformation management at our institution.

MATERIALS AND METHODS

Patients with low-grade brain arteriovenous malformations treated primarily with embolization in our department between January 2005 and December 2015 were retrieved from our prospectively collected registry. The primary outcome was the brain arteriovenous malformation obliteration rate, and secondary outcomes were disability or death secondary to brain arteriovenous malformation embolization assessed through modification of the modified Rankin Scale.

RESULTS

Two hundred twenty-four patients completed endovascular treatment during the study period and represent our study population. Complete exclusion of brain arteriovenous malformations was achieved in 205 patients (92%), including 62.1% of brain arteriovenous malformation exclusions after a single endovascular treatment session. One patient died of a hemorrhagic complication after endovascular treatment, leading to a mortality rate of 0.4%. Twelve patients (5%) kept a permanent neurologic deficit secondary to a complication of the endovascular treatment. An overall good outcome (mRS 0-2) was reported in 179 patients (80%).

CONCLUSIONS

Endovascular treatment might be a suitable alternative to surgical resection for complete exclusion of selected low-grade brain arteriovenous malformations.

Arterial-spin labeling MRI identifies residual cerebral arteriovenous malformation following stereotactic radiosurgery treatment

BACKGROUND AND PURPOSE

Brain arteriovenous malformation (AVM) treatment by stereotactic radiosurgery (SRS) is effective, but AVM obliteration following SRS may take two years or longer. MRI with arterial-spin labeling (ASL) may detect brain AVMs with high sensitivity. We determined whether brain MRI with ASL may accurately detect residual AVM following SRS treatment.

MATERIALS AND METHODS

We performed a retrospective cohort study of patients who underwent brain AVM evaluation by DSA between June 2010 and June 2015. Inclusion criteria were: (1) AVM treatment by SRS, (2) follow-up MRI with ASL at least 30 months after SRS, (3) DSA within 3 months of the follow-up MRI with ASL, and (4) no intervening AVM treatment between the MRI and DSA. Four neuroradiologists blindly and independently reviewed follow-up MRIs. Primary outcome measure was residual AVM indicated by abnormal venous ASL signal.

RESULTS

15 patients (12 females, mean age 29 years) met inclusion criteria. There were three posterior fossa AVMs and 12 supratentorial AVMs. Spetzler-Martin (SM) Grades were: SM1 (8%), SM2 (33%), SM3 (17%), SM4 (25%), and SM5 (17%). DSA demonstrated residual AVM in 10 patients. The pooled sensitivity, specificity, positive predictive value, and negative predictive value of venous ASL signal for predicting residual AVM were 100% (95% CI: 0.9-1.0), 95% (95% CI: 0.7-1.0), 98% (95% CI: 0.9-1.0), and 100% (95% CI: 0.8-1.0), respectively. High inter-reader agreement as found by Fleiss' Kappa analysis (k = 0.92; 95% CI: 0.8-1.0; P < 0.0001).

CONCLUSIONS

ASL is highly sensitive and specific in the detection of residual cerebral AVM following SRS treatment.

Reimagining ARUBA: Theoretical Optimization of the Treatment of Unruptured Brain Arteriovenous Malformations

BACKGROUND AND PURPOSE

The results of the A Randomized Trial of Unruptured Brain Arteriovenous (ARUBA) study, indicating that conservative medical management of unruptured brain arteriovenous malformations (UBAVM) is superior to interventional therapy, have generated debates that have hampered their application into clinical practice. Irrespectively of study conclusions, it seems reasonable to explore how much better interventional therapy would have to be to become competitive with conservative medical management.

METHODS

We conducted an exploratory analysis to replicate the original data from ARUBA. The functional form of the replicated ARUBA data, according to their Weibull distribution, allowed estimation of parameters. We carried out Monte Carlo simulations while introducing theoretical reductions of interventional risk, and the results were used to construct theoretical and example Kaplan-Meier curves from simulations.

RESULTS

The "ARUBA Replication" analysis showed results nearly identical to those published in the study, with an estimated hazard ratio of 0.27 (95% CI: 0.14-0.55). At 50% interventional risk reduction, the simulations showed an estimated event rate of 14.9%, and the protective effect of conservative medical management was no longer statistically significant. Greater risk reductions hastened the time to benefit for interventional therapy, and an 80% risk reduction demonstrated superiority of interventional therapy at just over 2 years Hazard Ratio (HR: 1.44, 95% CI: 0.55-4.92).

CONCLUSIONS

Reduction in risk of interventional therapy by 50%-80% results in more competitive clinical outcomes, equating or surpassing the benefit of conservative medical management of UBAVM. This conjecture should be taken into consideration in the design of future studies of this patient population, particularly because it is supported by recent observational studies.