Modern radiosurgical and endovascular classification schemes for brain arteriovenous malformations.

Stereotactic radiosurgery (SRS) and endovascular techniques are commonly used for treating brain arteriovenous malformations (bAVMs). They are usually used as ancillary techniques to microsurgery but may also be used as solitary treatment options. Careful patient selection requires a clear estimate of the treatment efficacy and complication rates for the individual patient. As such, classification schemes are an essential part of patient selection paradigm for each treatment modality. While the Spetzler-Martin grading system and its subsequent modifications are commonly used for microsurgical outcome prediction for bAVMs, the same system(s) may not be easily applicable to SRS and endovascular therapy. Several radiosurgical- and endovascular-based grading scales have been proposed for bAVMs. However, a comprehensive review of these systems including a discussion on their relative advantages and disadvantages is missing. This paper is dedicated to modern classification schemes designed for SRS and endovascular techniques.

Gamma knife radiosurgery for arteriovenous malformations: general principles and preliminary results in a Swiss cohort.

INTRODUCTION: Arteriovenous malformations (AVMs) are a type of vascular malformation characterised by an abnormal connection between arteries and veins, bypassing the capillary system. This absence of capillaries generates an elevated pressure (hyperdebit), in both the AVM and the venous drainage, increasing the risk of rupture. Management modalities are: observation, microsurgical clipping, endovascular treatment and radiosurgery. The former can be used alone or in the frame of a multidisciplinary approach. We review our single-institution experience with gamma knife radiosurgery (GKR) over a period of 5 years. MATERIALS AND METHODS: The study was open-label, prospective and nonrandomised. Fifty-seven consecutive patients, benefitting from 64 GKR treatments, were included. All were treated with Leksell Gamma Knife Perfexion (Elekta Instruments, AB, Sweden) between July 2010 and August 2015. All underwent stereotactic multimodal imaging: standard digital subtraction angiography, magnetic resonance imaging and computed tomography angiography. We report obliteration rates, radiation-induced complications and haemorrhages during follow-up course. RESULTS: The mean age was 46 years (range 13-79 years). The mean follow-up period was 36.4 months (median 38, range 12-75 months). Most common pretherapeutic clinical presentation was haemorrhage (50%). The most common Pollock-Flickinger score was between 1.01 and 1.5 (46%) and Spetzler-Martin grade III (46%). In 39 (60.1%) of cases, GKR was performed as upfront therapeutic option. The mean gross target volume (GTV) was 2.3 ml (median 1.2, range 0.03-11.3 ml). Mean marginal dose was 22.4 Gy (median 24, range 18-24 Gy). The mean prescription isodose volume (PIV) was 2.9 ml (median 1.8, range 0.065-14.6 ml). The overall obliteration rates (all treatments combined) at 12, 24, 36, 48 and 60 months were 4.8, 16.9%, 37.4, 63.6 and 78.4%, respectively. The main predictive factors for complete obliteration were: higher mean marginal dose (23.3 vs 21.0 Gy), lower GTV (mean 1.5 vs 3.5 ml) and absence of previous embolisation (at 60 months 61.8% prior embolisation compared with 82.4% without prior embolisation) (for all p <0.05). Eight (14%) patients experienced complications after GKR. Overall definitive morbidity rate was 3.1%. No patient died from causes related to GKR. However, during the obliteration period, one case of extremely rare fatal haemorrhage occurred. CONCLUSION: Radiosurgery is a safe and effective treatment modality for intracranial AVMs in selected cases. It can be used as upfront therapy or in the frame of a combined management. Obliteration rates are high, with minimal morbidity. The treatment effect is progressive and subsequent and regular clinical and radiological follow-up is needed to evaluate this effect.

Modern classification and outcome predictors of surgery in patients with brain arteriovenous malformations.

Brain arteriovenous malformations (bAVM) are challenging lesions. Part of this challenge stems from the infinite diversity of these lesions regarding shape, location, anatomy, and physiology. This diversity has called on a variety of treatment modalities for these lesions, of which microsurgical resection prevails as the mainstay of treatment. As such, outcome prediction and managing strategy mainly rely on unraveling the nature of these complex tangles and ways each lesion responds to various therapeutic modalities. This strategy needs the ability to decipher each lesion through accurate and efficient categorization. Therefore, classification schemes are essential parts of treatment planning and outcome prediction. This article summarizes different surgical classification schemes and outcome predictors proposed for bAVMs.

Stereotactic radiosurgery for Spetzler-Martin Grade IV and V arteriovenous malformations: an international multicenter study.

OBJECTIVE Due to the complexity of Spetzler-Martin (SM) Grade IV-V arteriovenous malformations (AVMs), the management of these lesions remains controversial. The aims of this multicenter, retrospective cohort study were to evaluate the outcomes after single-session stereotactic radiosurgery (SRS) for SM Grade IV-V AVMs and determine predictive factors. METHODS The authors retrospectively pooled data from 233 patients (mean age 33 years) with SM Grade IV (94.4%) or V AVMs (5.6%) treated with single-session SRS at 8 participating centers in the International Gamma Knife Research Foundation. Pre-SRS embolization was performed in 71 AVMs (30.5%). The mean nidus volume, SRS margin dose, and follow-up duration were 9.7 cm3, 17.3 Gy, and 84.5 months, respectively. Statistical analyses were performed to identify factors associated with post-SRS outcomes. RESULTS At a mean follow-up interval of 84.5 months, favorable outcome was defined as AVM obliteration, no post-SRS hemorrhage, and no permanently symptomatic radiation-induced changes (RIC) and was achieved in 26.2% of patients. The actuarial obliteration rates at 3, 7, 10, and 12 years were 15%, 34%, 37%, and 42%, respectively. The annual post-SRS hemorrhage rate was 3.0%. Symptomatic and permanent RIC occurred in 10.7% and 4% of the patients, respectively. Only larger AVM diameter (p = 0.04) was found to be an independent predictor of unfavorable outcome in the multivariate logistic regression analysis. The rate of favorable outcome was significantly lower for unruptured SM Grade IV-V AVMs compared with ruptured ones (p = 0.042). Prior embolization was a negative independent predictor of AVM obliteration (p = 0.024) and radiologically evident RIC (p = 0.05) in the respective multivariate analyses. CONCLUSIONS In this multi-institutional study, single-session SRS had limited efficacy in the management of SM Grade IV-V AVMs. Favorable outcome was only achieved in a minority of unruptured SM Grade IV-V AVMs, which supports less frequent utilization of SRS for the management of these lesions. A volume-staged SRS approach for large AVMs represents an alternative approach for high-grade AVMs, but it requires further investigation.

Multimodality Management of Spetzler-Martin Grade 3 Brain Arteriovenous Malformations with Subgroup Analysis.

OBJECTIVE: Spetzler-Martin grade 3 (SM3) lesions entail 4 distinct subtypes described based on size, eloquence, and deep venous drainage (3A-3D). The ideal management of each is contentious, and the results of A Randomized Trial of Unruptured Brain AVMs (ARUBA) introduced additional controversy and attention toward management strategies of unruptured brain arteriovenous malformations (bAVMs). METHODS: We retrospectively reviewed 114 patients with treated SM3 bAVMs, including both ruptured and unruptured lesions. Primary outcomes included modified Rankin score at most recent follow-up, angiographic cure, and permanent treatment-related complications (morbidity). Other outcomes included mortality, bAVM recurrence or rebleed, and transient treatment-related complications. We used univariate and multivariate modeling to determine whether any specific features were predictive of outcomes. For unruptured bAVMs, an "ARUBA eligible" subgroup analysis was performed. We also reviewed the literature on management of ruptured and unruptured SM3 bAVMs. RESULTS: Of the 114 identified SM3 bAVMs, 40% were unruptured. Most (43.5%) lesions in the unruptured group were type 3C, whereas most ruptured bAVMs (66.2%) were type 3A. Unruptured lesions were mostly managed with radiosurgery (47.8%) and ruptured ones with preoperative embolization and surgery (36.7%). Surgical intervention was predictive of angiographic cure in multivariate modeling, even after controlling for ≥2 years of follow-up, although associated with a slightly higher rate of morbidity. Focal neurological deficit was the only predictor of a worse (modified Rankin score ≥2) functional outcome in follow-up for unruptured bAVMs. For ruptured bAVMs, superficial and cerebellar locations were predictive of better outcomes in multivariate models, in the absence of a focal neurological deficit at presentation and new after surgery deficit. ARUBA SM3 bAVMs specifically underwent more embolization as a monotherapy and less microsurgical resection than the present series. CONCLUSIONS: In spite of a heterogeneous array of angioarchitectural and anatomic features, SM3 bAVMs can be treated safely and effectively with surgery and radiosurgery either without or with pretreatment embolization. Ruptured lesions are more often type 3A, with smaller nidus, deep brain location, and deep venous drainage. Focal neurological deficit predicts worse clinical outcomes. Contemporary multimodality management of SM3 bAVMs is not adequately represented in the results of ARUBA, likely due to differences in treatment strategies.

De novo development of a cerebral arteriovenous malformation following radiation therapy: Case report and an update to classical arteriovenous malformation nomenclature.

Cerebral arteriovenous malformations (AVM) are traditionally considered primary congenital lesions that result from embryological aberrations in vasculogenesis. Recent insights, however, suggest that these lesions may be secondary to a vascular insult such as ischemia or trauma. Herein, the authors present a rare case of a secondary cerebral AVM, occurring in a young girl who received prior cranial radiation therapy. At age 3years, she underwent surgical resection, chemotherapy, and photon radiation therapy for treatment of a fourth ventricular ependymoma. At age 19years, she developed new onset seizures and was found to have a left medial temporal lobe AVM. Her seizures were managed successfully with anti-epileptic medications and the AVM was treated with proton radiation therapy. This case highlights a rare but possible vascular sequela of radiation therapy and adds to the growing body of evidence that cerebral AVM may arise as secondary lesions.

SLAM: Stereotactic Radiosurgery of Large Arteriovenous Malformations: Meta-analysis of Hemorrhage in High-Grade Pollock-Flickinger Arteriovenous Malformations.

BACKGROUND: The prognosis of arteriovenous malformations (AVMs) after treatment has been predicted largely by 2 grading scales: the Spetzler-Martin and Pollock-Flickinger. Although there are studies that examine the rate of hemorrhage with the Spetzler-Martin scale, there have not been studies examining hemorrhage in which the Pollock-Flickinger score was used. The annual hemorrhage rate after radiosurgery of Pollock-Flickinger AVM scores >2 is analyzed. METHODS: Literature search for radiosurgery of large AVMs from January 1, 2000 to June 1, 2014 was conducted. Articles were examined for individual patient data and aggregate patient data that reported hemorrhage rates and mortality. Patients were only included if they had an AVM score ≥2. RESULTS: Annual AVM hemorrhage rate after radiosurgery for all patients (n = 673) was 3.22% (99.3 hemorrhages, 3080.5 follow-up years, 95% confidence interval [95% CI] 2.64%-3.89%). Mortality rate from hemorrhage was 40.08% (95% CI 31.21%-49.90%). A total of 203 patients presented with hemorrhage and 395 did not. In patients with first-time hemorrhage, the annual hemorrhage rate was 3.53% (95% CI 2.66%-4.77%). The annual hemorrhage rate of those with hemorrhagic presentation was 6.10% (95% CI 4.65%-8.07%). The odds ratio comparing re-hemorrhage rate versus first-time hemorrhage is 1.768 (95% CI 1.1571-2.7014, P = 0.0084). Complete obliteration of all AVMs was equal to 33.27% (95% CI, 29.25%-37.54%). CONCLUSIONS: The annual hemorrhage rate in AVMs with scores >2 treated with radiosurgery was comparable with baseline rupture rates reported for untreated AVMs. With further stratification by hemorrhagic versus nonhemorrhagic presentation, the subsequent annual hemorrhage rates are similar to their respective natural histories. Considering the mortality rate from hemorrhage at 40.08% (95% CI, 35.54%-44.62%), the consequences of radiosurgical treatment of large AVMs is significantly worse than the reported 10%-30% fatality rate from hemorrhage of an untreated AVM. Additionally, the overall mortality rate was 6.24% however the percentage of mortalities from hemorrhage was 97.62%.

Prospective Hemorrhage Rates of Cerebral Cavernous Malformations in Children and Adolescents Based on MRI Appearance.

BACKGROUND AND PURPOSE: Current classifications of cerebral cavernous malformations focus solely on morphologic aspects. Our aim was to provide a morphologic classification that reflects hemorrhage rates. MATERIALS AND METHODS: We retrospectively categorized 355 cavernous malformations of 70 children and adolescents according to their morphologic appearance on MR imaging and calculated prospective hemorrhage rates on the basis of survival functions for 255 lesions in 25 patients with a radiologic observation period of >180 days. RESULTS: Overall, there were 199 MR imaging examinations with 1558 distinct cavernous malformation observations during a cumulative observation period of 1094.2 lesion-years. The mean hemorrhage rate of all 355 cavernous malformations was 4.5% per lesion-year. According to Kaplan-Meier survival models, Zabramski type I and II cavernous malformations had a significantly higher hemorrhage rate than type III and IV lesions. The presence of acute or subacute blood-degradation products was the strongest indicator for an increased hemorrhage risk (P = .036, Cox regression): The mean annual hemorrhage rate and mean hemorrhage-free interval for cavernous malformations with and without signs of acute or subacute blood degradation products were 23.4% and 22.6 months and 3.4% and 27.9 months, respectively. Dot-sized cavernous malformations, visible in T2* and not or barely visible in T1WI and T2WI sequences, had a mean annual hemorrhage rate of 1.3% and a mean hemorrhage-free interval of 37.8 months. CONCLUSIONS: It is possible to predict hemorrhage rates based on the Zabramski classification. Our findings imply a tripartite classification distinguishing lesions with and without acute or subacute blood degradation products and dot-sized cavernous malformations.

Brainstem arteriovenous malformations: anatomical subtypes, assessment of "occlusion in situ" technique, and microsurgical results.

OBJECT: The surgical management of brainstem arteriovenous malformations (AVMs) might benefit from the definition of anatomical subtypes and refinements of resection techniques. Many brainstem AVMs sit extrinsically on pia mater rather than intrinsically in the parenchyma, allowing treatment by occluding feeding arteries circumferentially, interrupting draining veins after arteriovenous shunting is eliminated, and leaving the obliterated nidus behind. The authors report here the largest series of brainstem AVMs to define 6 subtypes, assess this "occlusion in situ" technique, and analyze the microsurgical results. METHODS: Brainstem AVMs were categorized as 1 of 6 types: anterior midbrain, posterior midbrain, anterior pontine, lateral pontine, anterior medullary, and lateral medullary AVMs. Data from a prospectively maintained AVM registry were reviewed to evaluate multidisciplinary treatment results. RESULTS: During a 15-year period, the authors treated 29 patients with brainstem AVMs located in the midbrain (1 anterior and 6 posterior), pons (6 anterior and 7 lateral), and medulla (1 anterior and 8 lateral). The nidus was pial in 26 cases and parenchymal in 3 cases. Twenty-three patients (79%) presented with hemorrhage. Brainstem AVMs were either resected (18 patients, 62%) or occluded in situ (11 patients, 38%). All lateral pontine AVMs were resected, and the occlusion in situ rate was highest with anterior pontine AVMs (83%). Angiography confirmed complete obliteration in 26 patients (89.6%). The surgical mortality rate was 6.9%, and the rate of permanent neurological deterioration was 13.8%. At follow-up (mean 1.3 years), good outcomes (modified Rankin Scale [mRS] score ≤ 2) were observed in 18 patients (66.7%) and poor outcomes (mRS score of 3-5) were observed in 9 patients (33.3%). The mRS scores in 21 patients (77.8%) were unchanged or improved. The best outcomes were observed with lateral pontine (100%) and lateral medullary (75%) AVMs, and the rate of worsening/death was greatest with posterior midbrain and anterior pontine AVMs (50% each). CONCLUSIONS: Brainstem AVMs can be differentiated by their location in the brainstem (midbrain, pons, or medulla) and the surface on which they are based (anterior, posterior, or lateral). Anatomical subtypes can help the neurosurgeon determine how to advise patients, with lateral subtypes being a favorable surgical indication along with extrinsic pial location and hemorrhagic presentation. Most AVMs are dissected with the intention to resect them, and occlusion in situ is reserved for those AVMs that do not separate cleanly from the brainstem, that penetrate into the parenchyma, or are more anterior in location, where it is difficult to visualize and preserve perforating arteries (anterior pontine and lateral medullary AVMs). Although surgical morbidity is considerable, surgery results in a better obliteration rate than nonoperative management and is indicated in highly selected patients with high rerupture risks.

A treatment paradigm for high-grade brain arteriovenous malformations: volume-staged radiosurgical downgrading followed by microsurgical resection.

OBJECT: The surgical treatment of many large arteriovenous malformations (AVMs) is associated with substantial risks, and many are considered inoperable. Furthermore, AVMs larger than 3 cm in diameter are not usually treated with conventional single-session radiosurgery encompassing the entire AVM volume. Volume-staged stereotactic radiosurgery (VS-SRS) is an option for large AVMs, but it has mixed results. The authors report on a series of patients with high-grade AVMs who underwent multiple VS-SRS sessions with resultant downgrading of the AVMs, followed by resection. METHODS: A cohort of patients was retrieved from a single-institution AVM patient registry consisting of prospectively collected data. VS-SRS was performed as a planned intentional treatment. Surgery was considered as salvage therapy in select patients. RESULTS: Sixteen AVMs underwent VS-SRS followed by surgery. Four AVMs presented with rupture. The mean patient age was 25.3 years (range 13-54 years). The average initial Spetzler-Martin grade before any treatment was 4, while the average supplemented Spetzler-Martin grade (Spetzler-Martin plus Lawton-Young) was 7.1. The average AVM size in maximum dimension was 5.9 cm (range 3.3-10 cm). All AVMs were supratentorial in location and all except one were in eloquent areas of the brain, with 7 involving primary motor cortex. The mean number of VS-SRS sessions was 2.7 (range 2-5 sessions). The mean interval between first VS-SRS session and resection was 5.7 years. There were 4 hemorrhages that occurred after VS-SRS. The average Spetzler-Martin grade was reduced to 2.5 (downgrade, -1.5) and the average supplemented Spetzler-Martin grade was reduced to 5.6 (downgrade, -1.5). The maximum AVM size was reduced to an average of 3.0 cm (downsize=-2.9 cm). The mean modified Rankin Scale (mRS) scores were 1.2, 2.3, and 2.2 before VS-SRS, before surgery, and at last follow-up, respectively (mean follow-up, 6.9 years). Fifteen AVMs were cured after surgery. Ten patients had good outcomes at last follow-up (7 with mRS Score 0 or 1, and 3 with mRS Score 2). There were 2 deaths (both mRS Score 1 before treatment) and 4 patients with mRS Score 3 outcome (from mRS Scores 0, 1, and 2 [n=2]). CONCLUSIONS: Volume-staged SRS can downgrade AVMs, transforming high-grade AVMs (initially considered inoperable) into operable AVMs with acceptable surgical risks. This treatment paradigm offers an alternative to conservative observation for young patients with unruptured AVMs and long life expectancy, where the risk of hemorrhage is substantial. Difficult AVMs were cured in 15 patients. Surgical morbidity associated with downgraded AVMs is reduced to that of postradiosurgical/preoperative supplemented Spetzler-Martin grades, not their initial AVM grades.

Surgical outcomes after classifying Grade III arteriovenous malformations according to Lawton's modified Spetzler-Martin grading system.

OBJECTIVE: We aimed to evaluate microsurgical outcomes after classifying Grade III arteriovenous malformations (AVMs) according to Lawton's modified Spetzler-Martin grading system. METHODS: Of 131 patients with Grade III AVMs, 55 had undergone microsurgery between 1995 and 2010. The 55 AVMs were classified as follows: Grade III-/S1E1V1, Grade III/S2E0V1, Grade III+/S2E1V0, or Grade III*/S3E0V0. The surgical obliteration rate, morbidity rate, and functional outcomes for each subtype were compared before surgery and after follow-up. Additionally, factors related with morbidity were investigated from demographic and morphological characteristics. RESULTS: We observed 18 Grade III-, 16 Grade III, 20 Grade III+, and 1 Grade III* AVMs. Complete resection was achieved in 49 patients (obliteration rate, 89.1%). Incomplete resection rates were higher for Grade III (12.5%) and III+ (15.0%) AVMs than that for Grade III- (5.6%) AVMs. Seven patients (12.7%) presented postoperative deficits, of which 3 (5.4%) experienced disabilities. Patients with Grade III+ (25.0%) had higher morbidity rates than those with other subtypes. Modified Rankin scale scores at the last follow-up indicated unfavorable outcomes for Grades III (18.8%) and III+ (25.0%) AVMs. AVM size (≥3 cm) and non-hemorrhagic type were associated with the occurrence of postoperative deficits (p<0.05). CONCLUSION: The modified classification of Grade III AVMs was useful to predict surgical morbidity and clinical outcomes. We recommend that microsurgery should be used to treat Grade III- AVMs, but should be considered carefully for the treatment of Grades III and III+.

Temporal lobe arteriovenous malformations: anatomical subtypes, surgical strategy, and outcomes.

OBJECT: Descriptions of temporal lobe arteriovenous malformations (AVMs) are inconsistent. To standardize reporting, the authors blended existing descriptions in the literature into an intuitive classification with 5 anatomical subtypes: lateral, medial, basal, sylvian, and ventricular. The authors' surgical experience with temporal lobe AVMs was reviewed according to these subtypes. METHODS: Eighty-eight patients with temporal lobe AVMs were treated surgically. RESULTS: Lateral temporal lobe AVMs were the most common (58 AVMs, 66%). Thirteen AVMs (15%) were medial, 9 (10%) were basal, and 5 (6%) were sylvian. Ventricular AVMs were least common (3 AVMs, 3%). A temporal craniotomy based over the ear was used in 64%. Complete AVM resection was achieved in 82 patients (93%). Four patients (5%) died in the perioperative period (6 in all were lost to follow-up); 71 (87%) of the remaining 82 patients had good outcomes (modified Rankin Scale scores 0-2); and 68 (83%) were unchanged or improved after surgery. CONCLUSIONS: Categorization of temporal AVMs into subtypes can assist with surgical planning and also standardize reporting. Lateral AVMs are the easiest to expose surgically, with circumferential access to feeding arteries and draining veins at the AVM margins. Basal AVMs require a subtemporal approach, often with some transcortical dissection through the inferior temporal gyrus. Medial AVMs are exposed tangentially with an orbitozygomatic craniotomy and transsylvian dissection of anterior choroidal artery and posterior cerebral artery feeders in the medial cisterns. Medial AVMs posterior to the cerebral peduncle require transcortical approaches through the temporo-occipital gyrus. Sylvian AVMs require a wide sylvian fissure split and differentiation of normal arteries, terminal feeding arteries, and transit arteries. Ventricular AVMs require a transcortical approach through the inferior temporal gyrus that avoids the Meyer loop. Surgical results with temporal lobe AVMs are generally good, and classifying them does not offer any prediction of surgical risk.

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.

Combined treatment of brain AVMs with use of Onyx embolization followed by radiosurgery.

BACKGROUND AND PURPOSE: The treatment of cerebral AVMs is complex, reliant on interventions such as embolization, surgery, and radiosurgery, or a combination of these modalities. To date, treatment with the embolic agent Onyx, followed by radiosurgery, has not been evaluated. The goal of this study was to evaluate the safety and efficacy of this combination in a homogeneous, monocentric series. MATERIALS AND METHODS: From April 2003 to June 2008, a total of 20 patients (11 women and 9 men; age range, 10-55 years) were treated for AVMs with Onyx embolization followed by radiosurgery. AVM sizes were <3 cm in 7 patients and ≥3 cm in 13 patients. Modalities and complications of the procedure were analyzed as well as the long-term clinical and anatomic outcomes (2-5 years after treatment). RESULTS: Of 17 patients evaluated by DSA after radiosurgery, 10 (58.8%) were observed to have complete occlusion of the AVM nidus. Complete occlusion was observed in 5 (71.4%) of 7 Spetzler-Martin grade I-II AVMs and in 5 (50.0%) of 10 Spetzler-Martin grade III-IV AVMs. Complete occlusion was observed in 4 (80.0%) of 5 AVMs of <3 cm and 6 (50.0%) of 12 AVMs of >3 cm. One of 20 patients had significant worsening of clinical status (mRS ≥2) at long-term follow-up. CONCLUSIONS: In this preliminary series, the safety and efficacy of combined treatment by Onyx embolization followed by radiosurgery are quite satisfactory, with a low rate of clinical complications (5.0%) and a 58.8% rate of complete obliteration of the AVM.

Surgical treatment of Spetzler-Martin grade III to V cerebral arteriovenous malformations: 10 years experience in Kyoto University.

Cerebral arteriovenous malformations (AVMs) are abnormal connections between arteries and veins leading to arteriovenous shunting with nidus formation. This study reviewed the clinical outcomes of surgical treatment for AVMs of Spetzler-Martin grades III to V in our institute. In addition, we summarized the technical aspects of surgical treatment for cerebral AVMs. Our development of the surgical modality for high-grade AVMs included intraoperative digital subtraction cerebral angiography, non-stick bipolar forceps, magnetic resonance tractography, and indocyanine green videoangiography. Excellent outcomes were obtained, but about 40% of all patients with AVMs could not receive surgical treatment. Multimodality approach including Onyx embolization may extend the surgical indications.

Multimodality treatment for cerebral arteriovenous malformations: complementary role of proton beam radiotherapy.

A total of 29 cerebral arteriovenous malformations (AVMs) treated at the University of Tsukuba with multimodality treatment including proton beam (PB) radiotherapy for cerebral AVMs between 2005 and 2011 were retrospectively evaluated. Eleven AVMs were classified as Spetzler-Martin grades I and II, 10 as grade III, and 8 as grades IV and V. For AVMs smaller than 2.5 cm and located on superficial and non-eloquent areas, surgical removal with/without embolization was offered as a first-line treatment. For some small AVMs located in deep or eloquent lesions, gamma knife (GK) radiosurgery was offered. Some AVMs were treated with only embolization. AVMs larger than 2.5 cm were embolized to achieve reduction in size, to enhance the safety of the surgery, and to render the AVM amenable to GK radiosurgery. For larger AVMs located in deep or eloquent areas, PB radiotherapy was offered with/without embolization. Immediately after the treatment, 24 patients exhibited no neurological worsening. Four patients had moderate disability, and 1 patient had severe disability. Three patients suffered brain damage after surgical resection, and 2 patients suffered embolization complications. However, no neurological worsening was observed after either GK radiosurgery or PB radiotherapy, but 3 patients treated by PB radiotherapy suffered delayed hemorrhage. Fractionated PB radiotherapy for cerebral AVMs seems to be useful for the treatment of large AVMs, but careful long-term follow up is required to establish the efficacy and safety.

Management of arteriovenous malformations related to Spetzler-Martin grading system.

Advanced technology and improved understanding of the natural history of arteriovenous malformations (AVMs) led to the reconsideration of the management of these lesions, which once comprised purely microsurgical removal. A multidisciplinary approach for both the evaluation and treatment of AVMs has gained acceptance within the past few decades. Treatment options for AVMs include surgical resection, embolization, or stereotactic radiosurgery, or any combination of these procedures. The risk of a chosen management strategy must include the sum of the risk of all the interventions applied to a given lesion, and this should be compared with the natural history of a given lesion in a particular clinical setting. Among all components of the multimodality treatment, however, microsurgical removal remains the definitive form of treatment.

[Radiosurgery for brain arteriovenous malformations]. / Radiochirurgie stéréotaxique des malformations artérioveineuses cérébrales.

Radiosurgery as treatment for arteriovenous malformations has shown a good efficacy in reducing intracranial bleeding due to rupture. The choice of therapeutic modalities is based on evolutive risk and arteriovenous malformations volume, patient profile and risks stratification following therapeutic techniques (microsurgery, radiosurgery, embolization). Nidus size, arteriovenous malformations anatomical localization, prior embolization or bleeding, distributed dose are predictive factors for radiosurgery's good results and tolerance. This review article will highlight arteriovenous malformations radiosurgery indications and discuss recent irradiation alternatives for large arteriovenous malformation volumes.

Nidal embolization of brain arteriovenous malformations: rates of cure, partial embolization, and clinical outcome.

OBJECT: Nidal embolization of brain arteriovenous malformations (bAVMs) has become an increasingly important component of bAVM treatment. However, controversy exists as to the relative efficacy and safety of single-stage versus multistage approaches to bAVM embolization, with recent literature favoring multistage strategies. The authors present a series of consecutive bAVMs embolized at their institution, demonstrating the safety and efficacy of a predominantly single-stage embolization strategy. The safety and efficacy of embolization are reported in the context of predetermined treatment strategies to provide more generalizable insight into treatment outcome. METHODS: One hundred thirty consecutive patients with 131 bAVMs underwent endovascular embolization at a single center. Diagnostic angiography with superselective microcatheterizations was performed in all patients. Postembolization angiograms were reviewed by 3 neuroradiologists for degree of occlusion and angiographic evidence of procedural complications. Patients were divided into cohorts based on the prospectively determined treatment strategy, which included the following: global devascularization of the bAVM (Devasc); targeting of a focal angioarchitectural weakness (Target), typically as an adjunct to surgery or Gamma Knife treatment; and primary occlusion of the bAVM by embolization alone (Occlude). Safety and efficacy were evaluated in the context of these treatment groups. RESULTS: The 131 bAVMs were treated over an average of 1.28 embolization sessions per bAVM; 105 bAVMs (80%) were treated in a single stage. The average percentage devascularization in the Devasc arm was 85.3%, which was statistically significantly greater than the 72% aggregate devascularization reported in 8 modern N-butyl cyanoacrylate and Onyx papers based on 1-sample Wilcoxon rank-sum testing (p<0.001). Focal angioarchitectural weaknesses were successfully embolized for all 24 bAVMs in the Target group, directly with the embolic agent in 23 bAVMs and indirectly in 1 bAVM with a venous aneurysm/pseudoaneurysm by reducing arterial inflow and inducing venous thrombosis. Lesions in all patients in the Occlude arm were 100% occluded with embolization alone. Overall, the bAVMs in the Occlude arm were significantly smaller and required embolization of fewer pedicles than those in the Devasc group. One patient (0.8%) experienced significant morbidity following embolization, and 1 patient in the cohort died (0.8%). CONCLUSIONS: This research communicates the authors' experience in developing a largely single-stage strategy for embolization of bAVMs. The results suggest that an aggressive, single-stage embolization may be implemented with a margin of safety and effectiveness similar to the multistage approaches more commonly reported in the literature. This work additionally introduces the importance of prospective assignment to a treatment strategy in assessing procedural outcome in bAVM embolization, thereby improving generalizability of the results and allowing for more rigorous interpretation of efficacy and safety.