Microsurgical treatment of arteriovenous malformations: analysis and comparison with stereotactic radiosurgery

Long-term outcomes and safety of Gamma Knife radiosurgery in pediatric arteriovenous malformations

PURPOSE

Despite the unique challenges presented by pediatric intracranial AVMs, little data is available on the use of GKRS in the pediatric population. Therefore, we aimed to present our experience with GKRS in treating pediatric AVMs, determining the factors that influence nidus obliteration and poor outcomes, with a focus on delayed complications.

METHODS

This retrospective review examined patients ≤18 years who underwent GKRS between January 2013 and December 2021 for intracranial AVMs. Factors that predicted residual nidus and poor outcomes were analyzed. The utility of AVM size reduction at follow-up in predicting eventual nidus obliteration was tested.

RESULTS

We treated 101 pediatric patients for AVMs with a mean age of 14.2 ± 2.8 years. The mean dose delivered was 22.7 ± 2.4 Gy. After a mean follow-up of 41.4 months, 78 AVMs (77.8%) were obliterated. Residual nidus was associated with prior embolization (HR 4.953; 95% CI 1.343, 18.268; p = 0.016) and age ≥14 years (HR 5.920; 95% CI 1.559, 22.480; p = 0.009) while presentation with bleed (HR 0.178; 95% CI 0.05, 0.631; p = 0.008) was protective. Reduction in size of a nidus during early follow-up closely correlated with eventual obliteration, with increasing accuracy at 6-month, 12-month, and 24-month follow-up (67.6%, 80.2%, and 86.5% respectively). Twelve patients developed perilesional edema, while one patient each developed a chronic encapsulated hematoma (CEH), cyst formation, and rebleed. Dose > 22 Gy (HR 25.641; 95% CI 2.257, 250; p = 0.009) and volume ≥ 3 cc (HR 7.189; 95% CI 1.176, 43.945; p = 0.033) predicted poor outcomes on multivariate analysis.

CONCLUSIONS

GKRS delivers a high rate of AVM nidus obliteration in the pediatric population, with prior embolization, older age, and unruptured presentation associated with residual nidus. The incidence of delayed complications, although low, warrants regular surveillance in the pediatric population due to their greater life expectancy.

Spetzler-Martin grade I and II cerebral arteriovenous malformations: a propensity-score matched analysis of resection and stereotactic radiosurgery in adult patients

Cerebral arteriovenous malformations (AVMs) are congenital vascular anomalies that can lead to severe complications, including hemorrhage and neurological deficits. This study compares the outcomes of microsurgical resection and stereotactic radiosurgery (SRS) for SM grade I and II AVMs. Out of a large multicenter registry, we identified 180 matched patients with SM grade I and II AVMs treated with either microsurgical resection or SRS between 2010 and 2023. The primary outcomes were AVM obliteration rates and complications; secondary outcomes included neurological status and functional outcomes measured by the modified Rankin Scale (mRS). Propensity score matching (PSM) was utilized to ensure comparability between treatment groups. After PSM, 90 patients were allocated to each treatment group. Significant differences were observed in complete obliteration rates, with resection achieving higher rates compared to SRS in overall cases (97.8% vs. 60.0%, p < 0.001), unruptured AVMs (100% vs. 58.3%, p < 0.001), and ruptured AVMs (95.2% vs. 61.9%, p < 0.001). Functional improvement rates were similar between the groups for overall cases (67.2% in resection vs. 66.7% in SRS, p = 0.95), unruptured AVMs (55.2% in resection vs. 55.6% in SRS, p > 0.9), and ruptured AVMs (78.1% in resection vs. 74.1% in SRS, p = 0.7). Symptomatic complication rates were identical between the groups (11.1% each, p > 0.9), while permanent complication rates were comparable (6.7% in resection vs. 5.6% in SRS, p = 0.8). Resection demonstrated significantly higher complete obliteration rates compared to SRS across all cases, including unruptured and ruptured AVMs. Functional improvement rates were similar between the two treatment groups, with no significant differences in symptomatic or permanent complication rates.

Feasibility of awake craniotomy for brain arteriovenous malformations: A scoping review

Background

Brain Arteriovenous Malformations (AVMs) located in proximity to eloquent brain regions are associated with poor surgical outcomes, which may be due to higher rates of postoperative neurological deterioration. Current treatment protocols include stereotactic radiosurgery, transarterial embolization, and surgical resection under general anesthesia. Awake Craniotomy (AC) allows intraoperative mapping of eloquent areas to improve post-operative neurologic outcomes.

Objectives

We reviewed the current literature reporting surgical outcomes and assessed the feasibility of AC for AVM resection.

Methods

The PRISMA guidelines were utilized as a template for the review. Three databases including PubMed, Scopus, and Cochrane Library were searched using a predefined search strategy. After removing duplicates and screening, full texts were analyzed. Outcomes including the extent of resection, intra-operative and post-operative complications, and long-term neurologic outcomes were assessed.

Results

12 studies were included with a total of 122 AVM cases. Spetzler-Martin grading was used for the classification of the AVMs. The asleep-awake-asleep protocol was most commonly used for AC. Complete resection was achieved in all cases except 5. Intraoperative complications included seizures (n = 2) and bleeding (n = 4). Short-term post-operative complications included hemorrhage (n = 3), neurologic dysfunctions including paresis (n = 3), hemiplegia (n = 10), dysphasia/aphasia (n = 6), cranial nerve dysfunction (n = 3), and pulmonary embolism (n = 1). Almost all neurological deficits after surgery gradually improved on subsequent follow-ups.

Conclusion

AVMs may shift the anatomical location of eloquent brain areas which may be mapped during AC. All studies recommended AC for the resection of AVMs in close proximity to eloquent areas as mapping during AC identifies the eloquent cortex thus promoting careful tissue handling which may preserve neurologic function and/or predict the postoperative functional status of the patients We, therefore, conclude that AC is a viable modality for AVMs resection near eloquent language and motor areas.

Quantitative Assessment of Hemodynamics Associated With Embolization Degree in Brain Arteriovenous Malformations

BACKGROUND AND OBJECTIVES

Grading systems, including the novel brain arteriovenous malformation endovascular grading scale (NBAVMES) and arteriovenous malformation embocure score (AVMES), predict embolization outcomes based on arteriovenous malformation (AVM) morphological features. The influence of hemodynamics on embolization outcomes remains unexplored. In this study, we investigated the relationship between hemodynamics and embolization outcomes.

METHODS

We conducted a retrospective study of 99 consecutive patients who underwent transarterial embolization at our institution between 2012 and 2018. Hemodynamic features of AVMs were derived from pre-embolization digital subtraction angiography sequences using quantitative digital subtraction angiography. Multivariate logistic regression analysis was performed to determine the significant factors associated with embolization outcomes.

RESULTS

Complete embolization (CE) was achieved in 17 (17.2%) patients, and near-complete embolization was achieved in 18 (18.2%) patients. A slower transnidal relative velocity (TRV, odds ratio [OR] = 0.71, P = .002) was significantly associated with CE. Moreover, higher stasis index of the drainage vein (OR = 16.53, P = .023), shorter transnidal time (OR = 0.15, P = .013), and slower TRV (OR = 0.9, P = .049) were significantly associated with complete or near-complete embolization (C/nCE). The area under the receiver operating characteristic curve for predicting CE was 0.87 for TRV, 0.72 for NBAVMES scores (ρ = 0.287, P = .004), and 0.76 for AVMES scores. The area under the receiver operating characteristic curve for predicting C/nCE was 0.77 for TRV, 0.61 for NBAVMES scores, and 0.75 for AVMES scores. Significant Spearman correlation was observed between TRV and NBAVMES scores and AVMES scores (ρ = 0.512, P < .001).

CONCLUSION

Preoperative hemodynamic factors have the potential to predict the outcomes of AVM embolization. A higher stasis index of the drainage vein, slower TRV, and shorter transnidal time may indicate a moderate blood flow status or favorable AVM characteristics that can potentially facilitate embolization.

Primary endovascular embolisation of intracranial arteriovenous malformations (AVM)-UK single centre experience

PURPOSE

Intracranial arteriovenous malformations (AVMs) treated at our institution with modern techniques of endovascular intervention were analysed for the rate of complete occlusion, associated morbidity, and mortality. To our knowledge, this is the first series from the UK evaluating the effectiveness of endovascular embolisation as a primary treatment for selected cases.

METHODS

All newly referred AVMs between January 2017 and June 2022 were reviewed and those treated with primary endovascular intervention were identified. Details of the endovascular procedures were retrospectively reviewed.

RESULTS

In 5½ years, 41.1% of AVMs referred to our institution have been triaged for primary endovascular intervention. Sixty-eight AVMs were embolised and followed-up: 44 ruptured and 24 unruptured. Spetzler-Martin grading varied from I to III, and a single AVM was grade IV. The approach was arterial in 73.5%, solely venous in 7.4%, and combined in 19.1%. The mean follow-up was 18 months for imaging and 26 months for clinical assessment. Complete obliteration was achieved in 95.6%. Ruptured AVM cohort: The rate of functional deterioration was 13.6%. Unruptured AVM cohort: The rate of functional deterioration secondary to complications from embolisation was 4.2%.

CONCLUSIONS

Endovascular embolisation may be a favourable option for primary AVM treatment in carefully selected patients. However, selection criteria need to be better delineated for more specialists to consider this as a primary therapy.

Chinese Cerebrovascular Neurosurgery Society and Chinese Interventional & Hybrid Operation Society, of Chinese Stroke Association Clinical Practice Guidelines for Management of Brain Arteriovenous Malformations in Eloquent Areas

Aim: The aim of this guideline is to present current and comprehensive recommendations for the management of brain arteriovenous malformations (bAVMs) located in eloquent areas. Methods: An extended literature search on MEDLINE was performed between Jan 1970 and May 2020. Eloquence-related literature was further screened and interpreted in different subcategories of this guideline. The writing group discussed narrative text and recommendations through group meetings and online video conferences. Recommendations followed the Applying Classification of Recommendations and Level of Evidence proposed by the American Heart Association/American Stroke Association. Prerelease review of the draft guideline was performed by four expert peer reviewers and by the members of Chinese Stroke Association. Results: In total, 809 out of 2,493 publications were identified to be related to eloquent structure or neurological functions of bAVMs. Three-hundred and forty-one publications were comprehensively interpreted and cited by this guideline. Evidence-based guidelines were presented for the clinical evaluation and treatment of bAVMs with eloquence involved. Topics focused on neuroanatomy of activated eloquent structure, functional neuroimaging, neurological assessment, indication, and recommendations of different therapeutic managements. Fifty-nine recommendations were summarized, including 20 in Class I, 30 in Class IIa, 9 in Class IIb, and 2 in Class III. Conclusions: The management of eloquent bAVMs remains challenging. With the evolutionary understanding of eloquent areas, the guideline highlights the assessment of eloquent bAVMs, and a strategy for decision-making in the management of eloquent bAVMs.

Retrospective Study and Outcome Predictor after Microsurgical Resection of Cerebral Arteriovenous Malformations in Nepal

Objective:

The purpose of this study is to assess demographic, clinical, and morphological characteristics of patients with brain arteriovenous malformations (bAVMs). The relation of outcome using modified Ranklin Scale (mRS) at time of discharge, early and last follow ups with respect to various factors.

Materials and Methods:

Demographic data, arteriovenous malformation characteristics, and treatment outcomes were evaluated in 43 bAVMs treated with microsurgery between 2009 and 2019. For this series, 43 patients were retrospectively reviewed. A subgroup analysis for Spetzler-Martin grades (SMG) I/II, III, IV/V and III–V were performed. The mRS was used to assess functional outcomes.

Results:

Overall, mean age at diagnosis was 33 years (standard deviation = 19). Transient deficit, mRS deterioration and impaired functional outcome occurred less frequently in SMG I–II patients compared with Grade III–V patients combined (29% vs. 32% respectively, P = 0.00). All patients with SMG Grade I, Supplemented SMG Grade 2, 3, 4 and 6 had a mRS score of 2 or less at the last follow-up. Age was the only significant predictor of overall outcome after bAVM surgery on Chi-square test (P = 0.046), i.e: all patients <20 years had mRS score of 2 or less on last follow-up. Unfavorable outcome (mRS score of 3 or more than 3) level increased with higher grades in SMG on long term follow-up.

Conclusion:

The results of our case series of bAVM with SMG Grade I and Suplemented Grade 2, 3, 4 and even higher grade i.e., 6 can have excellent overall outcome after microsurgical resection. Association of factors which increases the grading system of bAVM like eloquence, deep venous drainage and increasing sizes did not correlate with the predicted unfavorable outcomes, whereas age of patients was a predictor of overall outcome. Although the small sample size of this study is a limitation, age of patient plays important role on the overall outcome.

Surgical Treatment of Unruptured Brain AVMs: Short- and Long-Term Results

Unruptured brain AVMs (bAVMs) remain a controversial subject for practicing neurosurgeons, especially in the light of ARUBA and other observational studies. This retrospective study aims to analyze our experience with unruptured bAVMs to see whether it is beneficial in the long-term and how it corresponds to large literature trials. The study comprised 160 adult patients with unruptured bAVMs surgically treated in Burdenko NMC (Moscow) in 2009-2017. Mean age: 33.4 ± 10лет. Clinical presentations were: seizures in 99 (61.9%), chronical headaches-49 (30.6%), ischemic symptoms-4 (2.5%), asymptomatic in 8 (5%) patients. Spetzler-Martin scale: I-18 pt. (11.3%), II-71 pt. (44.4%), III-60 pt. (37.5%), IV-11 pt. (6.8%). Good outcomes (mRS = 0-2) at discharge were achieved in 149 (93.1%), satisfactory (mRS-3)-9 (5.6%). Follow-up was complete for 97 (60.6%) patients, mean-59.3 (13-108 month). Excellent outcomes (mRS = 0-1) reached in 94.8%. For epilepsy patients, Engel I outcome was found in 50 (84.8%); for chronic headaches, 43 (66.1%) patients reported improvement. Postoperative visual field defects were followed in 22 of 55 (40%), complete recovery was reported in 6 (27%) and partial recovery in 8 (36%) patients. Overall, our results support the conclusion that surgery for low-grade bAVMs (S-M I-II) is a beneficial, low-risk option.

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.

Microsurgery Versus Stereotactic Radiosurgery for Brain Arteriovenous Malformations: A Matched Cohort Study

BACKGROUND

Microsurgery (MS) and stereotactic radiosurgery (SRS) remain the preferred interventions for the curative treatment of brain arteriovenous malformations (AVM), but their relative efficacy remains incompletely defined.

OBJECTIVE

To compare the outcomes of MS to SRS for AVMs through a retrospective, matched cohort study.

METHODS

We evaluated institutional databases of AVM patients who underwent MS and SRS. MS-treated patients were matched, in a 1:1 ratio based on patient and AVM characteristics, to SRS-treated patients. Statistical analyses were performed to compare outcomes data between the 2 cohorts. The primary outcome was defined as AVM obliteration without a new permanent neurological deficit.

RESULTS

The matched MS and SRS cohorts were each comprised of 59 patients. Both radiological (85 vs 11 mo; P < .001) and clinical (92 vs 12 mo; P < .001) follow-up were significantly longer for the SRS cohort. The primary outcome was achieved in 69% of each cohort. The MS cohort had a significantly higher obliteration rate (98% vs 72%; P = .001), but also had a significantly higher rate of new permanent deficit (31% vs 10%; P = .011). The posttreatment hemorrhage rate was significantly higher for the SRS cohort (10% for SRS vs 0% for MS; P = .027). In subgroup analyses of ruptured and unruptured AVMs, no significant differences between the primary outcomes were observed.

CONCLUSION

For patients with comparable AVMs, MS and SRS afford similar rates of deficit-free obliteration. Nidal obliteration is more frequently achieved with MS, but this intervention also incurs a greater risk of new permanent neurological deficit.

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.

[Immediate outcomes of microsurgical treatment of cerebral arteriovenous malformations in non-hemorrhagic patients]

Arteriovenous malformations (AVMs) are some of the most frequent congenital abnormalities of the cerebral vascular system and usually occur at a young age. Given the fact that AVMs can manifest, in addition to hemorrhages, as symptomatic epilepsy (17-40%) that occurs more often at a young age and may lead to significant disability, investigation of this pathology remains topical. Particular attention has recently been paid to the management of AVM patients without clinical signs of hemorrhage at the time of pathology diagnosis.

OBJECTIVE

The objective of this study was to optimize the management of patients with unruptured AVMs based on analysis of the immediate outcomes of microsurgical treatment.

MATERIAL AND METHODS

We retrospectively analyzed the immediate outcomes of microsurgical treatment of AVM patients hospitalized to the Burdenko Neurosurgical Institute in the period from 2009 to 2017. The patients included in the study met the following criteria: age over 18 years; microsurgical resection of AVM. The main exclusion criterion was a hemorrhage history confirmed by clinical data or verified by a neuroimaging study (MRI/CT). The study included 160 patients (58.1% males and 41.9% females) aged 18 to 67 years (mean, 33.5 years). According to the clinical course, patients with epileptic syndrome prevailed: 99 (61.9%) cases. Headaches occurred in 49 (30.6%) patients; 8 (5%) patients had asymptomatic AVMs; 4 (2.5%) patients had ischemic stroke. The surgical risk was assessed by using the Spetzler-Martin (S-M) scale: Grade I - 18 (11.3%) patients, Grade II - 71 (44.4%) patients, Grade III - 60 (37.5%) patients, and Grade IV - 11 (6.8%) patients. Direct surgery in patients with AVMs classified as S-M V was not planned.

RESULTS

Postoperative analysis revealed that 33 patients included in the study group in accordance with the above criteria had silent AVM hemorrhage that was confirmed only based on the intraoperative picture. The best surgical treatment outcomes were observed in patients with S-M I and II AVMs. The outcome scored 4 and 5 on the Glasgow Outcome Scale (GOS) was in 100% of cases in the S-M I group, 98.6% in the S-M II group, 86.7% in the S-M III group, and 81.8% in the S-M IV group. The relatively good outcomes of S-M IV AVM resection are explained by careful selection of patients for surgery. In general, good postoperative outcomes (GOS score of 4 and 5) were in 93.2% of patients. The main newly developed postoperative symptoms were visual impairments - visual field defects (64.7% of all complications). Postoperative mortality was 1.3%.

CONCLUSION

Surgical treatment is indicated for patients with unruptured AVMs and S-M I or II surgical risk, regardless of clinical manifestations. In other cases, the treatment approach depends on a number of risk factors.

The Effect of Flow-Related Aneurysms on Hemorrhagic Risk of Intracranial Arteriovenous Malformations

BACKGROUND

Previous reports indicated an association between hemorrhagic presentation and flow-related aneurysms in arteriovenous malformation (AVM) patients. However, it remains unclear whether these flow-related aneurysms result in the hemorrhage of AVM.

OBJECTIVE

To characterize this hemorrhage risk using our institutional experience over 25 yr.

METHODS

We retrospectively reviewed records of patients at our institution diagnosed with AVM from 1990 to 2015. Patients without associated aneurysms (AVM only) and those with flow-related aneurysms (AVM-FA) were compared. Those with intranidal or unrelated aneurysms were excluded. Annual risk of AVM-related hemorrhage was calculated using the birth-to-treatment approach and compared using Poisson rate ratio test.

RESULTS

Among 526 patients, there were 457 AVM only patients and 69 with flow-related aneurysms. AVM-FA patients were older (P = .005). AVMs with flow-related aneurysms were more likely located in the cerebellar vermis and hemispheres (P = .023 and .001, respectively). Presence of flow-related aneurysms increased the risk of presentation with subarachnoid hemorrhage (P < .001). Interestingly, no significant differences in presenting hemorrhage due to AVM rupture were found (P > .356). The majority of aneurysms were untreated (69.5%), and only 8 (9.8%) had ruptured presentation. At follow-up (mean = 5.3 yr), patients with flow-related aneurysms were less likely to develop seizures (P = .004). The annual risk of AVM hemorrhage was 1.33% and 1.05% for AVM only patients and AVM-FA patients, respectively (P = .248).

CONCLUSION

Despite increased risk of subarachnoid hemorrhage at presentation, there was no increased likelihood of rupture in AVMs with flow-related aneurysms. More studies are warranted, as clarifying the competing risks of AVM vs aneurysm rupture may be critical in determining optimal treatment strategy.

Differences in Functional Outcome Across Subtypes with Spetzler-Martin Grade II Arteriovenous Malformations

BACKGROUND

The Spetzler-Martin grading system for brain arteriovenous malformations (AVMs) is based on size (S), eloquence (E), and deep venous drainage (V). However, variation exists due to subgroup heterogeneity. While previous studies have demonstrated variations in outcomes within grade III AVMs, no studies have focused on grade II AVM subtypes.

OBJECTIVE

We aim to delineate how functional outcomes differ among patients with subtypes of grade II AVMs.

METHODS

We retrospectively reviewed patients with AVMs evaluated at our institution from 1990 to 2013. Grade II AVMs were divided into 3 subtypes: group 1 (S2V0E0), group 2 (S1V0E1), and group 3 (S1V1E0). Baseline characteristics were compared, and functional status was assessed using the modified Rankin Scale (mRS) at pretreatment and last follow-up. Differences in mRS between the 2 time points were compared.

RESULTS

A total of 208 grade II patients (34.0%) were retrieved from 611 graded patients. After accounting for missing data, our cohort consisted of 137 patients. Mean age of all patients was 37.2 years, with 74 females (54.0%). No significant difference was observed across subgroups for pretreatment mRS ( P = .096), treatment modalities ( P = .943), follow-up durations ( P = .125), and mRS at last follow-up ( P = .716). In a subgroup analysis between group 1 and group 3, more patients with worsened mRS were observed in group 3 ( P = .039). This distinction was further confirmed in surgically treated patients ( P = .049), but not in patients treated with radiosurgery ( P = .863).

CONCLUSION

Subtypes of grade II AVMs portend different posttreatment gains in functional outcome. Group 1 (S2V0E0) patients had the best functional outcome gain from treatment, while group 3 (S1V1E0) patients fared less well, particularly with surgical treatment.

The 'radical combined approach' in cerebral arteriovenous malformation treatment: Technical note

AVMs are vessel anomalies where a connection between arterial and venous systems is present and the capillary bed is absent between the two. AVMs tend to present with seizures, headaches, focal neurological deficits and hemorrhage. Hemorrhage is the most common form of presentation. AVM's have a 2-4% annual risk of hemorrhage. Certain studies report this rate as 1%. The greatest discussion in AVM treatment is whether to use interventional treatment or monitor with medical treatment. There are 3 modalities that can be used for interventional treatment; microsurgical resection, endovascular embolization and stereotactic radiosurgery. Combined techniques are also possible. We defined the 'radical combined approach' combines embolization and microsurgery. We will discuss this procedure in this article as we believe it has several advantages.

Grade 1 Spetzler and Martin cerebral ruptured arteriovenous malformations treated by microsurgery: Poor functional outcome is related to injury from haemorrhage

INTRODUCTION

Ruptured arteriovenous malformations (rAVM) are life-threatening diseases.

OBJECTIVE

To evaluate the outcome of patients with grade 1 SPM rAVM after microsurgical treatment.

MATERIALS AND METHOD

We retrospectively included 64 consecutive operated patients with a grade 1 SPM rAVM in our institution between 2002 and 2012. Complications related to the surgical procedure were recorded. All patients were re-evaluated 3months after treatment using the modified Rankin Scale score (mRS). Persistent neurological disorders were evaluated 1year after bleeding. Conventional cerebral angiography was performed for each patient immediately after surgical treatment and 1year later.

RESULTS

The mean age at diagnosis was 30.8 years. Initial WFNS score was grade 1 in 25 patients, grade 2 in 11 patients, grade 3 in 10 patients, grade 4 in 9 patients and grade 5 in 9 patients. No remnant was left and a new surgery was performed only in a single patient who was initially operated-on under emergency conditions with limited preoperative investigations due to a poor clinical grade. Early postoperative complications related to the surgical procedure were recorded in 7 patients. The mRS score 3months after treatment was ≤2 in 53 patients (83%). Persistent neurological disorders were recorded in 40 patients (62.5%). High initial WFNS score (>2) and the hydrocephalus were significantly associated (P<0.05) to a bad functional outcome (mRS>2).

CONCLUSION

Grade 1 rAVM is a life-threatening disease concerning in most cases young patients. Long-term morbidity is often related to the hemorrhagic brain damage and rarely to the AVM resection.

Microsurgical Outcome of Unruptured Brain Arteriovenous Malformations: A Single-Center Experience

OBJECTIVE

We describe our single-center experience treating unruptured brain arteriovenous malformations (uBAVMs) with microsurgical treatment.

METHODS

During a 7-year period, 282 patients with uBAVMs were surgically treated at our institution. Patient clinical features, postsurgical complications, arteriovenous malformation obliteration rate, seizure control, and functional outcome were collected and analyzed. Seizure control was evaluated with the Engel classification system. Patient functional outcome was assessed with modified Rankin Scale score.

RESULTS

Complete obliteration was achieved in 98.2% of cases. Surgical mortality rate was zero, and overall mortality rate was 1.1%. Good functional outcome (modified Rankin Scale score 0-1) was achieved in 86.9% of all patients, including 92.5% of patients with Spetzler-Martin (S-M) grade I and II uBAVMs, 80.6% of patients with S-M grade III uBAVMs, and 62.5% of patients with S-M grade IV and V uBAVMs. Poor outcome was significantly associated with arteriovenous malformation size ≥6 cm, deep venous drainage, eloquent location, and poor seizure control (all P < 0.05). For 177 patients with presurgical seizures, good seizure outcome (Engel class I) was achieved in 124 (70.1%) patients after microsurgical treatment. A short history of seizure occurrence, fewer presurgical seizures, and generalized tonic-clonic seizure type may be predictors of good seizure outcome (all P < 0.05).

CONCLUSIONS

Good functional outcome can be achieved by microsurgical resection in S-M grade I and II and selected grade III uBAVMs. Surgical resection for high-grade (grade IV and V) uBAVMs is challenging. A high seizure-free rate can be achieved in patients with initial seizure presentation.

Screening for arteriovenous malformations in hereditary haemorrhagic telangiectasia

OBJECTIVE

To determine whether patients with hereditary haemorrhagic telangiectasia were being screened according to international guidelines, and to review recent evidence in order to provide up-to-date guidelines for the initial systemic management of hereditary haemorrhagic telangiectasia.

METHODS

A retrospective case note analysis was conducted, assessing patients in terms of screening for: genetics, cerebral arteriovenous malformations, pulmonary and hepatic arteriovenous malformations, and gastrointestinal telangiectasia. Databases searched included Medline, the Cumulative Index to Nursing and Allied Health Literature, and Embase.

RESULTS

Screening investigations were most frequently performed for hepatic arteriovenous malformations and least frequently for genetics. Recent data suggest avoiding routine genetic and cerebral arteriovenous malformation screening because of treatment morbidities; performing high-resolution chest computed tomography for pulmonary arteriovenous malformation screening; using capsule endoscopy (if possible) to reduce complications from upper gastrointestinal endoscopy; and omitting routine liver enzyme testing in favour of Doppler ultrasound.

CONCLUSION

Opportunities for systemic arteriovenous malformation screening are frequently overlooked. This review highlights the need for screening and considers the form in which it should be undertaken.

Comparative surgical outcome associated with the management of brain arteriovenous malformation in a regional neurosurgical centre

OBJECTIVES

Microsurgical resection of brain arteriovenous malformation (AVMs) is challenging, however, expert surgical series from large volume centres, have reported over 95% occlusion rates with 2 to 8% risk of morbidity & mortality. Data from a regional neurosurgical unit was analysed and compared with published series for the purposes of quality control. We also compared our surgical result with other treatment modalities from the whole AVM cohort managed over the same study period.

DESIGN

Retrospective analysis of a locally held AVM database.

SUBJECTS

Of the 141 AVM patients, 54 (35M, 19F, age range 9-68 years) underwent microsurgical removal of AVM by the senior author, from 2006 to 2012. 27 (19%), 18 (13%), 20 (14%), 22 (16%) had endovascular therapy only, radiosurgery only, combination therapy (endovascular and radiosurgery) and conservative management, respectively.

METHODS

Case notes were reviewed to determine clinical and radiological outcomes. Statistical analysis performed using SPSS with p < 0.05 defined as statistical significance.

RESULTS

In the surgical series, the Spetzler-Martin (SM) grade distribution was as follows: 17 grade I (32%), 31 grade II (57%), and 6 grade III (11%). 31 patients (57%) presented with intracranial haemorrhage, 12 patients (22%) with seizures. Of the 54 patients, 51 (94%) had angiographically confirmed obliteration of their AVM. Median follow-up for the entire cohort was 7 years. 83% of surgical patients have mRS 0-1, compared to 78%, 67%, 45%, 18% of patients managed by endovascular therapy, radiosurgery, combination therapy, conservative surveillance, respectively (p < 0.0001). However, the groups were not comparable in terms of SM grade or clinical presentation and the numbers in each group were relatively small. Seizure presentations were encountered in 23% (32/141) of the overall patients, and all the surviving patients were on anticonvulsants, except in the surgical arm, 7/12 (58%) patients were off their antiepileptic medications at last follow-up.

CONCLUSIONS

The results demonstrate a 94% surgical obliteration rate and 11% long-term neurological deficits for brain AVM patients managed surgically and were comparable to expert series. Achieving acceptable results is possible in lower volume settings, however, patient selection is important and the role of an experienced neurovascular team cannot be overstated.

Outcome of microsurgical excision of unruptured brain arteriovenous malformations in ARUBA-eligible patients

OBJECTIVES

To determine the outcome of microsurgical excision of selected unruptured brain arteriovenous malformations (AVMs), and to compare the results with those of the ARUBA trial.

METHODS

Prospective data collection for all patients undergoing microsurgical excision of unruptured brain AVMs by two neurovascular surgeons. Outcome measures similar to those assessed in the ARUBA trial (death and stroke) as well as modified Rankin scores (mRS) at 6 months were assessed.

RESULTS

Between September 2004 and September 2014, 45 patients with unruptured brain AVMs underwent microsurgical excision. 11 patients (eight children and three with mRS >2 at presentation) were excluded to match ARUBA eligibility criteria. 34 patients were included in this study. AVM characteristics closely matched those in the ARUBA trial with 70.5% Spetzler-Martin (SM) grade I or II AVMs, 68% AVM size <3 cm. However, compared to ARUBA, a larger proportion of our patients presented with seizures, and a lower proportion with headaches. 8(23%) had preoperative embolization. There were no deaths and no strokes (as defined in ARUBA). 5 (14.7%) had permanent neurological deficit related to surgery within/near eloquent cortex. At 6 months follow-up, 32 (94%) had mRS score of 0-1. Two (6%) had mRS 2 and none had mRS> 2. Postoperative digital DSA confirmed complete AVM excision in all cases. None of the patients have suffered intracranial hemorrhage during the follow-up period of 6-126 (median 69) months.

CONCLUSIONS

Microsurgical excision of unruptured brain AVMs can be performed with low morbidity in selected cases. Our study has limitations particularly the small number of patients with selected AVMs for microsurgical excision. However, our results suggest that ARUBA results may not be applicable to microsurgical excision when cases are appropriately selected for this treatment modality.

Using a Machine Learning Approach to Predict Outcomes after Radiosurgery for Cerebral Arteriovenous Malformations

Predictions of patient outcomes after a given therapy are fundamental to medical practice. We employ a machine learning approach towards predicting the outcomes after stereotactic radiosurgery for cerebral arteriovenous malformations (AVMs). Using three prospective databases, a machine learning approach of feature engineering and model optimization was implemented to create the most accurate predictor of AVM outcomes. Existing prognostic systems were scored for purposes of comparison. The final predictor was secondarily validated on an independent site's dataset not utilized for initial construction. Out of 1,810 patients, 1,674 to 1,291 patients depending upon time threshold, with 23 features were included for analysis and divided into training and validation sets. The best predictor had an average area under the curve (AUC) of 0.71 compared to existing clinical systems of 0.63 across all time points. On the heldout dataset, the predictor had an accuracy of around 0.74 at across all time thresholds with a specificity and sensitivity of 62% and 85% respectively. This machine learning approach was able to provide the best possible predictions of AVM radiosurgery outcomes of any method to date, identify a novel radiobiological feature (3D surface dose), and demonstrate a paradigm for further development of prognostic tools in medical care.

Therapeutic management of cerebral arteriovenous malformations: a review

The therapeutic management of cerebral arteriovenous malformations has undergone significant change over the past 40 years. Embolization, radiosurgery, advanced imaging modalities, neuropsychological testing and advances in surgical technique has both significantly improved our ability to treat patients, as well as confounding the landscape as to what constitutes best medical practice. Variability in natural history provides additional challenges in that it is challenging to determine an accurate estimate of the risk of hemorrhage, morbidity and mortality. It is clear that the complexity of the treatment of these lesions demands a multidisciplinary approach. The need for a team of neurosurgeons, interventional and diagnostic neuroradiologists, neurologists, radiation oncologists and neuropsychologists will improve outcomes and aid in determining best therapy for patients.

Surgical Management of Giant Intracranial Arteriovenous Malformations: A Single Center Experience over 32 years

OBJECTIVE

Treatment of giant intracranial arteriovenous malformations (gAVMs) is a formidable challenge for neurosurgeons and carries significant morbidity and mortality rates for patients compared with smaller AVMs. In this study, we reviewed the treatments, angiographic results, and clinical outcomes in 64 patients with gAVMs who were treated at Henry Ford Hospital between 1980 and 2012.

METHODS

The arteriovenous malformation (AVM) database at our institution was queried for patients with gAVMs (≥ 6 cm) and data regarding patient demographics, presentation, AVM angioarchitecture, and treatments were collected. Functional outcomes as well as complications were analyzed.

RESULTS

Of the 64 patients, 33 (51.6%) were female and 31 (48.4%) were male, with an average age of 45.7 years (SD ± 15.5). The most common symptoms on presentation were headaches (50%), seizures (50%), and hemorrhage (41%). The mean AVM size was 6.65 cm (range, 6-9 cm). Only 6 AVMs (9.4%) were located in the posterior fossa. The most common Spetzler-Martin grade was V, seen in 64% of patients. Of the 64 patients, 42 (66%) underwent surgical excision, 10 (15.5%) declined any treatment, 8 (12.5%) were deemed inoperable and followed conservatively, 2 (3%) had stand-alone embolization, 1 (1.5%) had embolization before stereotactic radiosurgery, and 1 (1.5%) received stereotactic radiosurgery only. Complete obliteration was achieved in 90% of the surgical patients. Mortality rate was 19% in the surgical cohort compared with 22% in the observation cohort (P = 0.770).

CONCLUSIONS

Treatment of gAVMs carries significant morbidity and mortality; however, good outcomes are attainable with a multimodal treatment approach in carefully selected patients.

The Diagnosis and Management of Brain Arteriovenous Malformations in a Single Regional Center

BACKGROUND

Cerebral arteriovenous malformations are vascular abnormalities in which arteriovenous shunting occurs through an abnormal vascular network (nidus) in the parenchyma. These lesions typically present by the third decade of life with cerebral bleeding, seizures, headache, or neurologic deficits; however, they are sometimes found incidentally.

METHODS

A retrospective analysis of intracranial AVMs referred to a single regional center, over a 7-year period, was performed to review the clinical presentation, pathologic features and management outcomes from January 2005 to December 2012.

RESULTS

We identified 142 patients (56% female, age range 4-69 years). Emergency referrals accounted for 87% of the cohort with the most frequent presentation being headache and/or hemorrhage. More than half (52%) of the cases were observed to have a neurologic deficit on examination. The modal Spetzler-Martin Grade was 3 with 76% of lesions located in areas of eloquent brain and 57% of cases in the dominant hemisphere. Half of the cases had multiple feeder vessels, and 29% were associated with aneurysms. The nidus was obliterated in 91% of cases actively managed. Two thirds of patients were successfully treated with a single modality, the most common being embolization. Only 8% of cases were managed conservatively. Additionally, 93% of aneurysms identified were treated successfully. The complication rate was 7% with 2% of reported infection.

CONCLUSIONS

The burden of AVM management is significantly enhanced by the number of emergency referrals. Interestingly, complication rates are higher in the unruptured cohort. Surgical management is the most effective modality, but it carries the highest complication rate. This accompanied by the challenges of AVM anatomy and associated pathology argue for expert service provision in a single center.

Arteriovenous malformation embocure score: AVMES

Background

Cerebral arteriovenous malformations (CAVMs) may be treated with microsurgery, radiosurgery, endovascular surgery, or a combination of these modalities. Grading scales are available to aid the assessment of curative risk for microsurgery and radiosurgery. No grading system has been developed to assess the curative risk of endovascular surgery.

Objective

To report our retrospective application of the AVM embocure score to patients treated at our institution between 2005 and 2011

Methods

We performed a retrospective review of 39 patients with CAVM treated at our institution between 2005 and 2011 with the primary aim of achieving a curative embolization. After reviewing all the different variables associated with the conventional Onyx embolization technique for CAVMs, we identified the following as the most relevant characteristics influencing the chances for complete angiographic embolization and complication risk: the number of arterial pedicles and draining veins, size of AVM nidus, and vascular eloquence. We sought to develop a scoring system to assess the complication risk for a curative embolization of CAVM with liquid embolic Onyx (Covidien, Irvine, California, USA). We developed the AVM embocure score (AVMES). This scoring system ranges from 3 to 10 and is the arithmetic sum of the number of arterial pedicles feeding the AVM (≤3, 4–6, >6), the number of draining veins (≤3, 4–6, >6), the size of the AVM nidus in centimeters (≤3, 4–6, >6), and the vascular eloquence (0–1). We applied AVMES to the same cohort of patients and validated the predictability of complete angiographic embolization and expected clinical risk of complication.

Results

In lesions with an AVMES of 3 (n=8), there was a 100% rate of complete AVM obliteration and 0% rate of major complications. In AVMES 4 (n=12) lesions, there was 75% complete obliteration rate, with 8% major morbidity. In AVMES 5 (n=9) lesions, there was 78% complete obliteration and 11% major morbidity. In AVMES >5 (n=10) there was 20% complete obliteration and 30% major morbidity. Receiver-operator curve analysis showed that this scoring system was robust in its discriminative ability, with an area under the curve (AUC) of 0.8356 for complete obliteration without complication, AUC=0.8240 for complete obliteration regardless of the presence of major morbidity, and AUC=0.7529 for major morbidity.

Conclusions

The AVMES complements existing scoring systems for microsurgery and radiosurgery. It provides a valuable tool for risk assessment during the complex decision-making process in treating AVMs that accounts for angioarchitectural features of particular relevance to endovascular surgeons.

Brain arteriovenous malformations

An arteriovenous malformation is a tangle of dysplastic vessels (nidus) fed by arteries and drained by veins without intervening capillaries, forming a high-flow, low-resistance shunt between the arterial and venous systems. Arteriovenous malformations in the brain have a low estimated prevalence but are an important cause of intracerebral haemorrhage in young adults. For previously unruptured malformations, bleeding rates are approximately 1% per year. Once ruptured, the subsequent risk increases fivefold, depending on associated aneurysms, deep locations, deep drainage and increasing age. Recent findings from novel animal models and genetic studies suggest that arteriovenous malformations, which were long considered congenital, arise from aberrant vasculogenesis, genetic mutations and/or angiogenesis after injury. The phenotypical characteristics of arteriovenous malformations differ among age groups, with fistulous lesions in children and nidal lesions in adults. Diagnosis mainly involves imaging techniques, including CT, MRI and angiography. Management includes observation, microsurgical resection, endovascular embolization and stereotactic radiosurgery, alone or in any combination. There is little consensus on how to manage patients with unruptured malformations; recent studies have shown that patients managed medically fared better than those with intervention at short-term follow-up. By contrast, interventional treatment is preferred following a ruptured malformation to prevent rehaemorrhage. Management continues to evolve as new mechanistic discoveries and reliable animal models raise the possibility of developing drugs that might prevent the formation of arteriovenous malformations, induce obliteration and/or stabilize vessels to reduce rupture risk. For an illustrated summary of this Primer, visit: http://go.nature.com/TMoAdn.

[The outcomes of stereotactic radiotherapy in patients with cerebral arteriovenous malformations]

INTRODUCTION

Cerebral arteriovenous malformations (AVMs) are the congenital anomalies of development of cerebral vessels during the embryonic period. The conventional therapy for AVMs currently includes endovascular management, microneurosurgical resection, and stereotactic irradiation.

MATERIAL AND METHODS

A total of 315 patients with brain AVMs were subjected to stereotactic radiotherapy in 2005-2011. 238 (76%) patients had previous subarachnoid hemorrhage (SAH) within different time (6 months to 5 years) before the therapy; 214 (68%) patients had headaches; 113 (36%) patients had focal neurological symptoms caused by localization; and 82 (26%) patients had seizures. Twenty-three patients were subjected to surgical resection of an intracerebral hematoma prior to radiotherapy and 119 (36%) patients received endovascular treatment including partial embolization of the stroma of AVM. 267 patients received single-fraction radiosurgical irradiation. In patients with large AVMs, we used the hypofractionation technique consisting in target irradiation with several (usually 2-7) fractions; the radiation dose per fraction exceeds 2 Gy. Forty-six patients were irradiated in the hypofractionation mode; two patients had a course of stereotactic radiotherapy in the standard fractionation mode. The marginal dose of radiosurgical irradiation was 13-30 Gy (the average dose was 24 Gy). The main group of patients (38 individuals) with large AVMs was treated using hypofractionation of 35 Gy per 5 fractions.

RESULTS

Control angiography was carried out in 225 patients who had been followed up for at least 2 years after therapy showed that complete obliteration was achieved in 83% of cases. The rate of symptomatic radiation reactions was less than 10%. The higher risk of developing obliteration was observed for AVMs less than 2 cm3 in size at marginal doses more than 24 Gy. In the hypofractionation group consisting of 27 patients with complete follow-up data, obliteration was observed in 10 (37%) patients. The rate of symptomatic reactions was less than 35%.

CONCLUSIONS

The radiosurgical method is a minimally invasive choice of treatment for patients with brain AVM, which allows one to achieve sufficiently high degree of obliteration with the minimum complication rate. The hypofractionation procedure is the method of choice for treating large AVMs. Stereotactic irradiation using the Novalis linear accelerator makes it possible to treat patients with AVMs of virtually any location and volume.

Current surgical results with low-grade brain arteriovenous malformations

OBJECT

Resection is an appealing therapy for brain arteriovenous malformations (AVMs) because of its high cure rate, low complication rate, and immediacy, and has become the first-line therapy for many AVMs. To clarify safety, efficacy, and outcomes associated with AVM resection in the aftermath of A Randomized Trial of Unruptured Brain AVMs (ARUBA), the authors reviewed their experience with low-grade AVMs-the most favorable AVMs for surgery and the ones most likely to have been selected for treatment outside of ARUBA's randomization process.

METHODS

A prospective AVM registry was searched to identify patients with Spetzler-Martin Grade I and II AVMs treated using resection during a 16-year period.

RESULTS

Of the 232 surgical patients included, 120 (52%) presented with hemorrhage, 33% had Spetzler-Martin Grade I, and 67% had Grade II AVMs. Overall, 99 patients (43%) underwent preoperative embolization, with unruptured AVMs embolized more often than ruptured AVMs. AVM resection was accomplished in all patients and confirmed angiographically in 218 patients (94%). There were no deaths among patients with unruptured AVMs. Good outcomes (modified Rankin Scale [mRS] score 0-1) were found in 78% of patients, with 97% improved or unchanged from their preoperative mRS scores. Patients with unruptured AVMs had better functional outcomes (91% good outcome vs 65% in the ruptured group, p = 0.0008), while relative outcomes were equivalent (98% improved/unchanged in patients with ruptured AVMs vs 96% in patients with unruptured AVMs).

CONCLUSIONS

Surgery should be regarded as the "gold standard" therapy for the majority of low-grade AVMs, utilizing conservative embolization as a preoperative adjunct. High surgical cure rates and excellent functional outcomes in patients with both ruptured and unruptured AVMs support a dominant surgical posture for low-grade AVMS, with radiosurgery reserved for risky AVMs in deep, inaccessible, and highly eloquent locations. Despite the technological advances in endovascular and radiosurgical therapy, surgery still offers the best cure rate, lowest risk profile, and greatest protection against hemorrhage for low-grade AVMs. ARUBA results are influenced by a low randomization rate, bias toward nonsurgical therapies, a shortage of surgical expertise, a lower rate of complete AVM obliteration, a higher rate of delayed hemorrhage, and short study duration. Another randomized trial is needed to reestablish the role of surgery in unruptured AVM management.

Cerebral arteriovenous malformations: evaluation and management

There has been increased detection of incidental AVMs as result of the frequent use of advanced imaging techniques. The natural history of AVM is poorly understood and its management is controversial. This review provides an overview of the epidemiology, pathophysiology, natural history, clinical presentation, diagnosis, and management of AVMs. The authors discussed the imaging techniques available for detecting AVMs with regard to the advantages and disadvantages of each imaging modality. Furthermore, this review paper discusses the factors that must be considered for the most appropriate management strategy (based on the current evidence in the literature) and the risks and benefits of each management option.

Radiosurgery for low-grade intracranial arteriovenous malformations

OBJECT

Low-grade, or Spetzler-Martin (SM) Grades I and II, arteriovenous malformations (AVMs) are associated with lower surgical morbidity rates than higher-grade lesions. While radiosurgery is now widely accepted as an effective treatment approach for AVMs, the risks and benefits of the procedure for low-grade AVMs, as compared with microsurgery, remain poorly understood. The authors of this study present the outcomes for a large cohort of low-grade AVMs treated with radiosurgery.

METHODS

From an institutional radiosurgery database comprising approximately 1450 AVM cases, all patients with SM Grade I and II lesions were identified. Patients with less than 2 years of radiological follow-up, except those with complete AVM obliteration, were excluded from analysis. Univariate and multivariate Cox proportional-hazards and logistic regression analyses were used to determine factors associated with obliteration, radiation-induced changes (RICs), and hemorrhage following radiosurgery.

RESULTS

Five hundred two patients harboring low-grade AVMs were eligible for analysis. The median age was 35 years, 50% of patients were male, and the most common presentation was hemorrhage (47%). The median AVM volume and prescription dose were 2.4 cm(3) and 23 Gy, respectively. The median radiological and clinical follow-up intervals were 48 and 62 months, respectively. The cumulative obliteration rate was 76%. The median time to obliteration was 40 months, and the actuarial obliteration rates were 66% and 80% at 5 and 10 years, respectively. Independent predictors of obliteration were no preradiosurgery embolization (p < 0.001), decreased AVM volume (p = 0.005), single draining vein (p = 0.013), lower radiosurgery-based AVM scale score (p = 0.016), and lower Virginia Radiosurgery AVM Scale (Virginia RAS) score (p = 0.001). The annual postradiosurgery hemorrhage rate was 1.4% with increased AVM volume (p = 0.034) and lower prescription dose (p = 0.006) as independent predictors. Symptomatic and permanent RICs were observed in 8.2% and 1.4% of patients, respectively. No preradiosurgery hemorrhage (p = 0.011), a decreased prescription dose (p = 0.038), and a higher Virginia RAS score (p = 0.001) were independently associated with postradiosurgery RICs.

CONCLUSIONS

Spetzler-Martin Grade I and II AVMs are very amenable to successful treatment with stereotactic radiosurgery. While patient, physician, and institutional preferences frequently dictate the final course of treatment, radiosurgery offers a favorable risk-to-benefit profile for the management of low-grade AVMs.

Evaluation of prognostic factors as predictor of AVMS obliteration after Gamma Knife radiosurgery

BACKGROUND

The reported AVMs obliteration rate after Gamma Knife radiosurgery (GKS) ranges from 70 to 94 %. The objective of the present study was to assess prognostic factors predictive for cerebral AVMs obliteration in 127 patients who underwent GKS.

METHODS

The AVMs were classified according to the Spetzler-Martin classification. Twenty-one cases (16.5 %) were classified as grade I, 46 cases (36.2 %) as grade II, 51 cases (40.1 %) as grade III, and nine cases (7.1 %) as grade IV-V. The AVMs were deeply located in 16.5 % of patients. The peripheral prescription dose ranged from 16 to 30 Gy (mean 22.3 Gy). The AVMs volume ranged from 0.1 to 13 cc (mean 2.7 cc).

RESULTS

In 72 patients out of the 104 (69.2 %) with a radiological follow-up, MRI showed the AVM obliteration; in 54 cases (60 %) out of the 90 that performed a DSA, a complete AVM obliteration was achieved (average closure time 48.5 months). The volume of the nidus (p = 0.001), the prescription dose (p = 0.004), the 2002 Pollock-Flickinger classification (p = 0.031), and their 2008 revised classification (p = 0.025) were found to be statistically significant in predicting the probability of AVM closure. In the multivariate analysis, only the prescription dose was found to be an independent prognostic factor (p = 0.009) for AVM obliteration.

CONCLUSIONS

The volume of the nidus and the prescription dose significantly influence the outcome of radiosurgical treatment. The Pollock-Flickinger classification was found to be a reliable scoring system in predicting the AVM closure and an important tool for selection of patients candidate for GKS.

Treatment for brain arteriovenous malformation in the 1998-2011 period and review of the literature

PURPOSE

The results of the treatment of pial AVM provided at our neurosurgical centre are presented. Based on these results and on an overview of literary data on the efficacy and complications of each therapeutic modality, the algorithm of indications, as used at our institution, is presented. COHORT OF PATIENTS: The series comprises 195 patients, aged 9 to 87 years and treated in the years 1998-2011. The surgical group consists of 76 patients; of these, 49 patients solely received endovascular treatment, 25 were consulted and referred directly to the radiosurgical unit, and the remaining 45 were recommended to abide by the strategy of "watch and wait".

RESULTS

In the surgical group, serious complications were 3.9 %, at a 96.1 % therapeutic efficacy. As for AVM treated with purely endovascular methods, serious procedural complications were seen in 4.1 % of patients, with efficacy totalling 32.7 %. One observed patient suffered bleeding, resulting in death. For comparison with literary data for each modality, a survival analysis without haemorrhage following monotherapy for AVM with each particular modality was carried out.

CONCLUSIONS

Based on our analysis, we have devised the following algorithm of treatment: 1. We regard surgical treatment as the treatment of choice for AVM of Spetzler-Martin (S-M) grades I and II, and only for those grade III cases that are surgically accessible. 2. Endovascular intervention should mainly be used for preoperative embolisation, as a curative procedure for lower-grade AVM in patients with comorbidities, and as palliation only for higher-grade cases. 3. Stereotactic irradiation with Leksell Gamma Knife (LGK) is advisable, mainly for poorly accessible, deep-seated grade-III AV malformations. In the case of lower grades, the final decision is left to the properly informed patient. 4. Observation should be used as the method of choice in AVM of grades IV and V, where active therapy carries greater risk than the natural course of the disease.

Spinal glomus (type II) arteriovenous malformations: a pooled analysis of hemorrhage risk and results of intervention

BACKGROUND

The natural history and treatment results for spinal glomus (type II) arteriovenous malformations (AVMs) remain relatively obscure.

OBJECTIVE

To calculate spinal glomus (type II) AVM hemorrhages rates and amalgamate results of intervention.

METHODS

We performed a pooled analysis via the PubMed database through May 2012, including studies with at least 3 cases. Data on individual patients were extracted and analyzed using a Cox proportional hazards regression model to obtain hazard ratios for hemorrhage risk factors.

RESULTS

The annual hemorrhage rate before treatment was 4% (95% confidence interval [confidence interval]: 3%-6%), increasing to 10% (95% CI: 7%-16%) for AVMs with previous hemorrhage. The hazard ratio for hemorrhage after hemorrhagic presentation was 2.25 (95% CI: 0.71-7.07), increasing to 13.0 within the first 10 years (95% CI: 1.44-118). The overall rates of complete obliteration were 78% (95% CI: 72%-83%) for surgery and 33% (95% CI: 24%-43%) for endovascular treatment. Long-term clinical worsening occurred in 12% of patients after surgical treatment (95% CI: 8%-16%) and in 13% after endovascular treatment (95% CI: 7%-21%). No hemorrhages occurred after complete obliteration. After partial surgical treatment, the annual hemorrhage rate was 3% (95% CI: 1%-6%); no hemorrhages were reported over 196 patient-years after partial endovascular treatment.

CONCLUSION

Spinal glomus (type II) AVMs with previous hemorrhage, particularly within 10 years, demonstrated a greater risk of hemorrhage. Complete obliteration and even partial endovascular treatment significantly decreased their hemorrhage rate.

Management of ruptured brain arteriovenous malformations

Intracranial arteriovenous malformations (AVMs) are a common cause of stroke in younger patients, and often present as intracerebral hemorrhages (ICH), associated with 10 % to 30 % mortality. Patients who present with a hemorrhage from an AVM should be initially stabilized according to acute management guidelines for ICH. The characteristics of a lesion including its size, location in eloquent tissue, and high-risk features will influence risk of rupture, prognosis, as well as help guide management decisions. Given that rupture is associated with an increased risk of 6 % re-rupture in the year following the initial hemorrhage, versus 1 % to 3 % predicted annual risk in non-ruptured lesions only, definitive treatment is encouraged after ICH stabilization. A rest period of 2 to 6 weeks after hemorrhage is recommended before definitive treatment to avoid disrupting friable parenchyma and the hematoma. Treatment may consist of endovascular embolization, surgical resection, radiosurgery, or a combination of these three interventions based on the lesion.

Intra operative indocyanine green video-angiography in cerebrovascular surgery: An overview with review of literature

Microscope integrated Near infra red Indocyanine green video angiography (NIR ICG VA) has been frequently used in cerebrovascular surgery. It is believed to be a simple and reliable method with acquisition of real time high spatial resolution images. The aim of this review article was to evaluate the efficacy of intra operative Indocyanine green video angiography (ICG VA) in Aneurysm, brain arteriovenous malformations (AVM) and extracranial-intracranial (EC-IC) bypass surgeries and also to analyze its limitations. Intra operative imaging is a very useful tool in guiding surgery; thus, avoiding surgical morbidity. Now-a-days, many cerebrovascular units are using ICG VA rather than Doppler and intra operative DSA in most of their aneurysm surgeries, and surgeons are incorporating this technique for AVM and in EC-IC bypass surgeries too. This article is an overview of the beneficial effects of ICG VA in cerebrovascular surgery and will also point out its limitations in various circumstances. Intra operative ICG VA gives high resolution, real time images of arterial, capillary, and venous flow of cerebral vasculature. Although it gives adequate information about the clipped neck, parent/branching artery and perforator involvement, it has some limitations like viewing the neck residuals located behind the aneurysm, thick walled atherosclerotic vessels, and thrombosed aneurysms. In AVM surgery, it is useful in detecting the residual nidus in diffuse type AVM, but cannot be relied in deep seated AVMs and it gives exact information about the anastomosis site in EC-IC bypass, thus, avoiding early bypass graft failure. NIR ICG VA is a simple, reliable, and quick method to pick up subtle findings in cerebrovascular procedures. But in selected cases of aneurysms, endoscopy and intra operative Digital substraction angiography (DSA) may be helpful, whereas in deep seated AVMs, navigation may be required as an adjunct to confirm intra operative findings.

Surgical and radiosurgical results of the treatment of cerebral arteriovenous malformations

Microsurgical resection of a cerebral arteriovenous malformation (AVM) allows for an immediate therapeutic cure. Stereotactic radiosurgery (SRS) is a reasonable alternative for inoperable or high-risk lesions requiring treatment. Few series evaluate overall results that include data from both modalities as they more often focus on their treatment method of choice. In this study, we evaluated our AVM database of 129 patients seen over the past eight years at our institution: 73 were treated with microsurgery (57%) while 37 (29%) were treated with SRS. We reviewed angiographic obliteration rates, complication rates, and outcome data, excluding seven patients treated with SRS as they did not have at least two years of angiographic follow-up. Patients undergoing microsurgery had smaller AVM (mean 2.2 cm compared to 3.5 cm for SRS), a smaller proportion of eloquent AVM (53% compared to 83% for SRS), a greater proportion of AVM with superficial drainage only (75% compared to 40% for SRS), and more grade 1 and 2 AVM (78% compared to 17% for SRS). The overall obliteration rate was 80%: 92% for microsurgery and 50% for SRS. The latter increased to 92% for AVM <3 cm, but the obliteration rate was 18% for those AVM >3 cm. Transient complications, including post-SRS hemorrhage, were seen in 11% of patients overall (8% after microsurgery, 17% after SRS). At follow-up, 53% of patients had improved, 37% remained the same, 7% had become worse and 3% had died. As a result of post-SRS hemorrhage, a greater proportion of patients was worse or had died after SRS (20%) compared to those who had been treated with microsurgery (5%).

Stereotactic radiosurgery of cranial arteriovenous malformations and dural arteriovenous fistulas

Cranial arteriovenous malformations (AVM) and cranial dural arteriovenous fistulas (AVF) carry a significant risk of morbidity and mortality when they hemorrhage. Current treatment options include surgery, embolization, radiosurgery, or a combination of these treatments. Radiosurgery is thought to reduce the risk hemorrhage in AVMs and AVFs by obliterating of the nidus of abnormal vasculature over the course of 2 to 3 years. Success in treating AVMs is variable depending on the volume of the lesion, the radiation dose, and the pattern of vascular supply and drainage. This article discusses the considerations for selecting radiosurgery as a treatment modality in patients who present with AVMs and AVFs.

Stereotactic radiosurgery for arteriovenous malformations, Part 1: management of Spetzler-Martin Grade I and II arteriovenous malformations

Object

The aim of this paper was to define the outcomes and risks of stereotactic radiosurgery (SRS) for Spetzler-Martin Grade I and II arteriovenous malformations (AVMs).

Methods

Between 1987 and 2006, the authors performed Gamma Knife surgery in 996 patients with brain AVMs, including 217 patients with AVMs classified as Spetzler-Martin Grade I or II. The median maximum diameter and target volumes were 1.9 cm (range 0.5–3.8 cm) and 2.3 cm3 (range 0.1–14.1 cm3), respectively. The median margin dose was 22 Gy (range 15–27 Gy).

Results

Arteriovenous malformation obliteration was confirmed by MR imaging in 148 patients and by angiography in 100 patients with a median follow-up of 64 months (range 6–247 months). The actuarial rates of total obliteration determined by angiography or MR imaging after 1 SRS procedure were 58%, 87%, 90%, and 93% at 3, 4, 5, and 10 years, respectively. The median time to complete MR imaging–determined obliteration was 30 months. Factors associated with higher AVM obliteration rates were smaller AVM target volume, smaller maximum diameter, and greater marginal dose. Thirteen patients (6%) suffered hemorrhages during the latency period, and 6 patients died. Cumulative rates of AVM hemorrhage 1, 2, 3, 5, and 10 years after SRS were 3.7%, 4.2%, 4.2%, 5.0%, and 6.1%, respectively. This corresponded to rates of annual bleeding risk of 3.7%, 0.3%, and 0.2% for Years 0–1, 1–5, and 5–10, respectively, after SRS. The presence of a coexisting aneurysm proximal to the AVM correlated with a significantly higher hemorrhage risk. Temporary symptomatic adverse radiation effects developed in 5 patients (2.3%) after SRS, and 2 patients (1%) developed delayed cysts.

Conclusions

Stereotactic radiosurgery is a gradually effective and relatively safe option for patients with smaller volume Spetzler-Martin Grade I or II AVMs who decline initial resection. Hemorrhage after obliteration did not occur in this series. Patients remain at risk for a bleeding event during the latency interval until obliteration occurs. Patients with aneurysms and an AVM warrant more aggressive surgical or endovascular treatment to reduce the risk of a hemorrhage in the latency period after SRS.

How to deal with incompletely treated AVMs: experience of 67 cases and review of the literature

INTRODUCTION

Despite the availability of multimodal treatment options, some arteriovenous malformations remain difficult to treat, either for intrinsic reasons at initial presentation or for reasons evolving during the course of treatment. Frequently, such cases can be easily resolved with further therapy, but some become a continuously growing treatment dilemma while exhausting dwindling therapeutic options.

PATIENTS AND METHODS

A retrospective analysis was performed to identify patients with cerebral AVM who were treated unsuccessfully. Treatment was termed "not successful" if (1) postoperative angiography showed a residual AVM or missing flow reduction after palliative embolization, (2) therapy was associated with a substantial deterioration of existing neurological deficits or death, or (3) rebleeding from residual AVM occurred after therapy. Special interest was focused on the angiographic appearance of residual AVMs, their characteristic features, and their follow-up regarding second and third therapies.

RESULTS

According to these criteria we identified 46 internal patients from our own series of 474 patients and 21 external patients who were referred from other institutions or sought a second opinion after incomplete treatment elsewhere. Out of those 67 cases, 50 patients (74.6%) were diagnosed with a residual AVM. Eleven patients (16.4%) experienced a deterioration of their clinical condition under therapy. Six patients did not show a flow reduction after palliative embolization. Twenty-five of the 67 patients were readmitted because of an ICH, either originating from an AVM residual or under palliative embolization. Thus, an increased risk of re-hemorrhage was found for palliative embolization (n = 16) in partially treated lesions (n = 10) and in patients with AVM grade IV and V located in eloquent regions (n = 22). In dealing with residual AVMs, microsurgical resection alone or in combination was found to be the most efficient therapeutic option, being successful in 58.9% of cases.

CONCLUSION

An estimated 10% of AVM treatments may fail because of inadequate selection of either patients or management. Besides, for thorough decision-making, angiographic follow-up in all AVM patients is mandatory to allow an early identification of patients with an incompletely treated AVM requiring a second attempt. Major attention should be focused especially on high-risk subgroups with complex AVMs, partially treated AVMs, or those treated by only a palliative regimen.

Radiosurgical management of pediatric arteriovenous malformations

PURPOSE

Hemorrhage from an arteriovenous malformation (AVM) is the commonest cause of childhood stroke. Management options for children include observation and medical management, surgical resection, endovascular embolization, or stereotactic radiosurgery, alone or in combination.

METHODS

Radiosurgery is used for high-risk malformations in critical brain locations. While this goal is being achieved, there should be limited morbidity and hopefully no mortality from hemorrhage or radiation-induced brain injury.

RESULTS

Physicians who consider AVM radiosurgery cite one or more of the following: (1) that radiosurgery is an effective therapy required for the management of deep-brain AVMs; (2) that radiosurgery is an effective therapy for residual AVMs after subtotal resection; (3) that radiosurgery is worthwhile in an attempt to lower management risks for AVMs in functional brain locations; (4) since embolization does not cure most AVMs, additional therapy such as radiosurgery may be required; and (5) microsurgical resection may not be the best choice for some children.

CONCLUSION

Radiosurgery is the first and only biologic AVM therapy; it represents the beginnings of future cellular approaches to vascular malformation diseases. For this reason, the future of radiosurgery may be impacted positively by the development of other biologic strategies such as brain protection or endothelial sensitization.

Simple technique for intraoperative angiographic localization of small vascular lesions

BACKGROUND

Precise surgical localization of small arteriovenous malformations (AVMs), arteriovenous fistulae (AVFs), and aneurysms located in the distal portions of the intracranial arteries can be difficult.

OBJECTIVE

We describe a simple and accurate intraoperative angiographic localization technique for small AVMs, AVFs, and distal aneurysms.

METHODS

All patients had routine preoperative diagnostic imaging and evaluations, including catheter angiography. Once anesthetized, the patients were prepared for intraoperative angiography following cannulation of the femoral artery. Craniometric landmarks were utilized to approximately localize the lesion. A wire in the shape of a square was placed over the proposed craniotomy site and an angiogram was performed. With use of real-time angiography, the wire localizer was manipulated until the small vascular lesion was visualized entirely within the wire frame, thus defining the extent of the required craniotomy and the surgical trajectory.

RESULTS

The wire localizer was used to target small vascular lesions in 9 cases of AVMs, 4 cases of distal middle cerebral artery aneurysms, and 1 case of a diploic AVF. In all 14 cases, the lesion was accurately localized intraoperatively without further image-guided techniques, and there was no change in the craniotomy. There were no intraoperative complications, and all patients had uneventful recoveries.

CONCLUSION

Intraoperative angiography with a simple wire localizer can effectively and accurately aid in the planning of surgery for a range of small and distal vascular lesions with virtually no added cost, minimal setup time, and limited potential for technical errors.

Validation of the radiosurgery-based arteriovenous malformation score in a large linear accelerator radiosurgery experience

Object

The radiosurgery-based arteriovenous malformation (AVM) score (RBAS) is a grading system designed to predict patient outcomes after Gamma Knife surgery for AVMs. This study seeks to validate independently the predictive nature of the RBAS, not only after single treatment but for retreatment, and to assess the overall outcome regardless of number of radiosurgeries.

Methods

The authors analyzed 403 patients treated with linear accelerator (LINAC) radiosurgery for AVMs between May 1988 and June 2008. The AVM scores were determined by the following equation: AVM score = (0.1 × volume in cm3) + (0.02 × age in years) + (0.3 × location). The location values are as follows: frontal/temporal = 0, parietal/occipital/corpus callosum/cerebellar = 1, and basal ganglia/thalamus/brainstem = 2.

Results

Testing demonstrated that the RBAS correlated with excellent outcomes after single or repeat radiosurgery (p < 0.001 for both variables). One hundred sixty-two (49%) of 330 patients had excellent outcomes (obliteration without deficit) after a single treatment. Excellent outcomes were achieved in 74, 64, 50, and 11% of patients with AVM scores of < 1.0 (Group 1), between 1.0 and < 1.8 (Group 2), between 1.8 and < 2.5 (Group 3), and ≥ 2.5 (Group 4), respectively. Fifty-one patients (70%) obtained radiosurgical cure and 46 (63%) achieved excellent outcomes after repeat radiosurgery. Of these, 100% achieved excellent outcomes in Group 1, 70% did so in Group 2, 47% in Group 3, and 14% in Group 4. The RBAS correlated with excellent outcomes after overall treatment (p < 0.001). Two hundred seventy-seven patients (69%) obtained AVM obliteration, and 62% achieved excellent outcomes. In Group 1, 87% achieved excellent outcomes, 75% did so in Group 2, 61% in Group 3, and 24% in Group 4.

Conclusions

The RBAS is a good predictor of patient outcomes after LINAC radiosurgery.