Stereotactic Radiosurgery for Arteriovenous Malformations Located in Deep Critical Regions

Considerations for the Use of Stereotactic Radiosurgery to Treat Large Arteriovenous Malformations

Stereotactic radiosurgery (SRS) is an effective treatment strategy for cerebral arteriovenous malformations (AVMs). Aggressive treatment achieving complete obliteration is necessary to prevent further intracranial hemorrhage and neurological deficits. However, SRS treatment of large AVMs (>10 cm3) is challenging. To prevent toxicity in the normal brain tissue, it is imperative to reduce the radiation dose as the lesion volume increases; however, this also reduces the rate of obliteration. In this study, we review the various radiosurgical approaches for treating large AVMs and their outcomes, and suggest ways to improve treatment outcomes during SRS for large AVMs.

Repeat Single-Session Stereotactic Radiosurgery for Cerebral Arteriovenous Malformations: A Systematic Review, Meta-Analysis, and International Stereotactic Radiosurgery Society Practice Guidelines

BACKGROUND AND OBJECTIVES

Repeat stereotactic radiosurgery (SRS) for residual arteriovenous malformations (AVMs) can be considered as a salvage approach after failure of initial SRS. There are no published guidelines regarding patient selection, timing, or SRS parameters to guide clinical practice. This systematic review aimed to review outcomes and complications from the published literature to inform practice recommendations provided on behalf of the International Stereotactic Radiosurgery Society.

METHODS

We performed a systematic review and meta-analysis following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A comprehensive search of MEDLINE, Scopus, Web of Science, and Embase was conducted. Fourteen studies with 925 patients met the inclusion criteria. Patients were treated between 1985 and 2022. All studies were retrospective, except for one prospective cohort.

RESULTS

The median patient age at repeat SRS ranged from 32 to 60 years. Four studies (630 patients) reported detailed information on Spetzler-Martin grade at the time of repeat SRS; 12.54% of patients had Spetzler-Martin grade I AVMs (79/630 patients), 46.51% had grade II (293/630), 34.92% had grade III (220/630), 5.08% had grade IV (32/630), and 0.95% had grade V (6/630). The median prescription doses varied between 15 and 25 Gy (mean, 13.06-22.8 Gy). The pooled overall obliteration rate at the last follow-up after repeat SRS was 59% (95% CI 51%-67%) with a median follow-up between 21 and 50 months. The pooled hemorrhage incidence at the last follow-up was 5% (95% CI 4%-7%), and the pooled overall radiation-induced change incidence was 12% (95% CI 7%-20%).

CONCLUSION

For an incompletely obliterated AVM, repeat radiosurgery after 3 to 5 years of follow-up from the first SRS provides a reasonable benefit to the risk profile. After repeat SRS, obliteration is achieved in the majority of patients. The risk of hemorrhage or radiation-induced change appears low, and International Stereotactic Radiosurgery Society recommendations are presented.

Repeat single-session stereotactic radiosurgery for arteriovenous malformation: a systematic review and meta-analysis

BACKGROUND

Stereotactic radiosurgery is the preferred option for treating brain arteriovenous malformation (AVM) when the risks associated with surgery outweigh the potential benefits. However, some patients require repeat radiosurgery due to residual AVM after the first procedure. This systematic review and meta-analysis aimed to investigate the safety and efficacy of repeated procedure of radiosurgery for AVM.

METHOD

A systematic review was conducted according to the PRISMA guideline. The search was conducted on PubMed, Scopus, Embase, and Web of Science, using a pre-designed search string. Studies investigating the efficacy of repeat radiosurgery for residual AVM following initial single session radiosurgery were included. The risk of bias was assessed using the JBI tool. Meta-analysis and met-regression were performed to pool and inspect data.

RESULTS

Our meta-analysis, with a mean follow-up of 45.57 months, reveals repeat radiosurgery as a viable option for arteriovenous malformations (AVMs), achieving a 60.82% obliteration rate with a mean time to obliteration of 33.18 months. Meta-regression identifies AVM volume and Spetzler-Martin (SM) grade as factors influencing obliteration, with smaller volume and lower SM grades associated with higher rates. Complications include 10.33% radiation-induced changes, 5.26% post-radiosurgery hemorrhage, 2.56% neurologic deficits, and 0.67% cyst formation. Heterogeneity in complications is primarily attributed to male proportion and SM grade, while factors influencing post-radiosurgery hemorrhage remain unclear. The type of radiosurgery, whether Gamma Knife Radiosurgery (GKRS) or LINAC, does not significantly impact outcomes.

CONCLUSION

Repeat radiosurgery is a feasible, effective, and safe treatment for AVMs following failure of initial radiosurgery. When utilized in appropriate patient subgroups, it provides an acceptable risk-to-benefit profile. Feature studies are required to clarify its clear indications.

Third Stereotactic Radiosurgery for Residual Arteriovenous Malformations: A Retrospective Multicenter Study

BACKGROUND AND OBJECTIVES

There are no studies evaluating the efficacy and safety of more than 2 stereotactic radiosurgery (SRS) procedures for cerebral arteriovenous malformations (AVM). The aim of this study was to provide evidence on the role of third single-session SRS for AVM residual.

METHODS

This multicenter, retrospective study included patients managed with a third single-session SRS procedure for an AVM residual. The primary study outcome was defined as AVM nidus obliteration without AVM bleeding or symptomatic radiation-induced changes (RIC). Secondary outcomes evaluated were AVM obliteration, AVM hemorrhage, asymptomatic, and symptomatic RIC.

RESULTS

Thirty-eight patients (20/38 [52.6%] females, median age at third SRS 34.5 [IQR 20] years) were included. The median clinical follow-up was 46 (IQR 14.8) months, and 17/38 (44.7%) patients achieved favorable outcome. The 3-year and 5-year cumulative probability rates of favorable outcome were 23% (95% CI = 10%-38%) and 53% (95% CI = 29%-73%), respectively. The cumulative probability of AVM obliteration at 3 and 5 years after the third SRS was 23% (95% CI = 10%-37%) and 54% (95% CI = 29%-74%), respectively. AVM bleeding occurred in 2 patients, and 1 of them underwent subsequent resection. The cumulative probability rate of post-SRS AVM hemorrhage remained constant at 5.3% (95% CI = 1%-16%) during the first 5 years of follow-up. Transient symptomatic RIC managed conservatively occurred in 5/38 patients (13.2%) at a median time of 12.5 (IQR 22.5) months from third SRS. Radiation-induced cyst formation was noted in 1 patient (4.2%) 19 months post-SRS. No mortality, radiation-associated malignancy, or permanent symptomatic RIC was noted during follow-up.

CONCLUSION

A third single-session SRS to treat a residual intracranial AVM offers obliteration in most patients. The risk of RIC was low, and these effects were transient. While not often required, a third SRS can be performed in patients with persistent residual AVMs.

Endovascular embolization for basal ganglia and thalamic arteriovenous malformations

Background

Basal ganglia and thalamic arteriovenous malformations (AVMs) represent a special subset of malformations. Due to the involvement of vital brain structures and the specifically fine and delicate angioarchitecture of these lesions, it presents unique therapeutic challenges and technical difficulties that require thorough treatment planning, individualized treatment strategies, and advanced techniques for good clinical outcome.

Method

In this study, we presented a series of ruptured basal ganglia and thalamic AVMs embolized via a transarterial, transvenous or combined approach. Herein, we summarized our treatment experience and clinical outcomes to further evaluate the effectiveness and safety of endovascular embolization for these AVMs as well as the indications, therapy strategies, and techniques of embolization procedures.

Results

Twelve patients with basal ganglia and thalamus AVMs were included in the study. Their average age was 23.83 ± 16.51 years (range, 4-57 years) with a female predominance of 67% at presentation. The AVMs were located in the thalamus in 3 (25%) patients, in the basal ganglia in 3 (25%) patients, and in both sites of the brain in 6 (50%) patients. There were 5 AVMs located on the left side and 7 on the right. The mean nidus diameter was 3.32 ± 1.43 cm (range 1.3-6.1 cm). According to the Spetzler-Martin grading classification, 4 (33.3%) brain AVMs were Grade III, 7 (58.3%) were Grade IV, and 1 (8.3%) was Grade V. All of them presented with bleeding at admission: four of these patients presented with an intracerebral hemorrhage (ICH), 8 ICH in combination with intraventricular hemorrhage (IVH), and no patient with subarachnoid hemorrhage (SAH). Among these patients treated with endovascular embolization, 7 patients were treated by the transarterial approach, 4 patients transvenous approach, and 1 patient underwent the combined approach. A single embolization procedure was performed in 6 patients (50%) and the other 6 cases (50%) were treated in a staged manner with up to three procedures. Procedure-related complications occurred only in two patient (16.7%). Complete AVM obliteration was obtained in 7 patients (58.3%), and partial obliteration was in 4 patients (33.3%). Overall, good or excellent outcomes were obtained in 7 patients (58.3%), and poor functional outcome was observed in 5 patients (41.7%) at the last follow-up. All survived patients achieved anatomic stabilization and there was no postoperative bleeding or recurrence in the follow-up.

Conclusion

The management of the basal ganglia and thalamic AVMs is a great challenge, which needs multimodal individualized treatment to improve the chances of radiographic cure and good outcomes. Endovascular therapy is safe and effective in the treatment of cerebral AVMs particularly for deep-seated AVMs such as the basal ganglia and thalamus. Our results demonstrate a high rate of anatomic obliteration with an acceptable rate of complications in the endovascular treatment of these vasculopathies via a transarterial approach or a transvenous approach.

Frameless versus frame-based stereotactic radiosurgery for intracranial arteriovenous malformations: A propensity-matched analysis

Objective

The frameless linear accelerator (LINAC) based stereotactic radiosurgery (SRS) has been evolving with a reduction in patient discomfort. However, there was limited evidence comparing frame-based and frameless SRS for intracranial arteriovenous malformations (AVM). We aimed to compare the treatment outcomes between frame-based and frameless LINAC SRS.

Materials and Methods

This retrospective cohort compared the outcomes of frame-based LINAC SRS (1998-2009) with frameless LINAC SRS (2010-2020). The primary outcome was the obliteration rate. The other outcomes included the neurological, radiological, and functional outcomes after SRS. A matched cohort was identified by propensity scores for further comparisons.

Results

A total of 65 patients were included with a mean follow-up time of 13.2 years (158.5 months). There were 40 patients in the frame-based group and 25 patients in the frameless group. The overall obliteration rate was comparable (Frame-based 82.5% vs Frameless 80.0%, p = 0.310) and not significantly different over time (log-rank p = 0.536). The crude post-SRS hemorrhage rate was 1.5% and the incidence was 0.3 per 100 person-years. There were 67.7% of patients with AVM obliteration without new persistent neurological deficits at the last visit and 56.9% of patients with AVM obliteration without any deficits (transient or persistent) during the entire follow-up period. Four patients (8.0%) developed late onset persistent adverse radiation effects (more than 96 months after SRS) among 50 patients with more than 8-year surveillance. In the propensity-matched cohort of 42 patients, there was no significant difference in AVM obliteration (Frame-based vs Frameless, log-rank p = 0.984).

Conclusion

Frameless and frame-based LINAC SRS have comparable efficacy in intracranial AVM obliteration. A longer follow-up duration may further characterize the rate of late adverse radiation effects in frameless SRS.

Stereotactic radiosurgery outcome for deep-seated cerebral arteriovenous malformations in the brainstem and thalamus/basal ganglia: systematic review and meta-analysis

Deep-seated unruptured AVMs located in the thalamus, basal ganglia, or brainstem have a higher risk of hemorrhage compared to superficial AVMs and surgical resection is more challenging. Our systematic review and meta-analysis provide a comprehensive summary of the stereotactic radiosurgery (SRS) outcomes for deep-seated AVMs. This study follows the guidelines set forth by the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) Statement. We conducted a systematic search in December 2022 for all reports of deep-seated arteriovenous malformations treated with SRS. Thirty-four studies (2508 patients) were included. The mean obliteration rate in brainstem AVM was 67% (95% CI: 0.60-0.73), with significant inter-study heterogeneity (tau2 = 0.0113, I2 = 67%, chi2 = 55.33, df = 16, p-value < 0.01). The mean obliteration rate in basal ganglia/thalamus AVM was 65% (95% CI: 0.58-0.72) with significant inter-study heterogeneity (tau2 = 0.0150, I2 = 78%, chi2 = 81.79, df = 15, p-value < 0.01). The presence of deep draining veins (p-value: 0.02) and marginal radiation dose (p-value: 0.04) were positively correlated with obliteration rate in brainstem AVMs. The mean incidence of hemorrhage after treatment was 7% for the brainstem and 9% for basal ganglia/thalamus AVMs (95% CI: 0.05-0.09 and 95% CI: 0.05-0.12, respectively). The meta-regression analysis demonstrated a significant positive correlation (p-value < 0.001) between post-operative hemorrhagic events and several factors, including ruptured lesion, previous surgery, and Ponce C classification in basal ganglia/thalamus AVMs. The present study found that radiosurgery appears to be a safe and effective modality in treating brainstem, thalamus, and basal ganglia AVMs, as evidenced by satisfactory rates of lesion obliteration and post-surgical hemorrhage.

Microenvironment changes in arteriovenous malformations after stereotactic radiation

Cerebral arteriovenous malformations are dysplastic vascular tangles with aberrant vascular dynamics and can result significant morbidity and mortality. A myriad of challenges are encountered when treating these lesions and are largely based on nidal size, location, and prior hemorrhage. Currently, stereotactic radiosurgery is an accepted form of treatment for small to medium sized lesions and is especially useful in the treatment of lesions in non-surgically assessable eloquent areas of the brain. Despite overall high rates of nidal obliteration, there is relatively limited understand on the mechanisms that drive the inflammatory and obliterative pathways observed after treatment with stereotactic radiosurgery. This review provides an overview of arteriovenous malformations with respect to stereotactic radiosurgery and the current understanding of the mechanisms that lead to nidal obliteration.

The Thalamic Arteriovenous Malformations Have Better Prognosis than Basal Ganglia Malformations Regarding Obliteration: Prognostic Factors Analysis

BACKGROUND

Arteriovenous malformations (AVMs) are rare vascular congenital lesions that affect mainly patients during their productive years of life. In order to obtain a better quality of life for patients with this disease, a multidisciplinary approach is recommended. Radiosurgery is one of the treatment modalities available for AVMs, but many factors may influence the effectiveness of this strategy. Classically, it has been said that deep-seated lesions have a particular behavior compared with AVMs in other regions, but a differentiation between thalamic lesions and those located in the basal ganglia has not been made.

METHODS

Institutional records for central core AVMs treated with radiosurgery between January 2004 and January 2014 were retrospectively analyzed. Brainstem lesions were excluded from the analysis.

RESULTS

Forty-nine patients with deep-seated AVMs were included. Forty-three (87.8%) were located in the thalamus and 6 (12.2%) in the area of basal ganglia. The nidus mean volume was 4.1 cm³ (SD: 4.1), the maximum diameter mean was of 19.5 mm (SD: 8.0). The prescription dose was 18.2 Gy (SD: 2.1), and the follow-up time was 75.8 months (SD: 32.5). There was a greater obliteration rate in thalamic AVMs compared with those located in the basal ganglia: 81.4% versus 33.3% (P = 0.026), respectively. There was no association between categorical variables and obliteration rate.

CONCLUSIONS

Stereotactic radiosurgery is a good option for patients with thalamic and basal ganglia AVMs, but a multidisciplinary approach to decision-making is mandatory in order to achieve the best results.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Stereotactic Radiosurgery for Brain Arteriovenous Malformations: Evaluation of Obliteration and Review of Associated Predictors

BACKGROUND

High arteriovenous malformation (AVM) obliteration rates have been reported with stereotactic radiosurgery (SRS), and multiple factors have been found to be associated with AVM obliteration. These predictors have been inconsistent throughout studies. We aimed to analyze our experience with linear accelerator (LINAC)-based SRS for brain AVMs, evaluate outcomes, assess factors associated with AVM obliteration and review the various reported predictors of AVM obliteration.

METHODS

Electronic medical records were retrospectively reviewed to identify consecutive patients with brain AVMs treated with SRS over a 27-year period with at least 2 years of follow-up. Logistic regression analysis was performed to identify factors associated with AVM obliteration.

RESULTS

One hundred twenty-eight patients with 142 brain AVMs treated with SRS were included. Mean age was 34.4 years. Fifty-two percent of AVMs were associated with a hemorrhage before SRS, and 14.8% were previously embolized. Mean clinical and angiographic follow-up times were 67.8 months and 58.6 months, respectively. The median Spetzler-Martin grade was 3. Mean maximal AVM diameter was 2.8 cm and mean AVM target volume was 7.4 cm³ with a median radiation dose of 16 Gy. Complete AVM obliteration was achieved in 80.3%. Radiation-related signs and symptoms were encountered in 32.4%, only 4.9% of which consisted of a permanent deficit. Post-SRS AVM-related hemorrhage occurred in 6.3% of cases. In multivariate analysis, factors associated with AVM obliteration included younger patient age (P = .019), male gender (P = .008), smaller AVM diameter (P = .04), smaller AVM target volume (P = .009), smaller isodose surface volume (P = .005), a higher delivered radiation dose (P = .013), and having only one major draining vein (P = .04).

CONCLUSIONS

AVM obliteration with LINAC-based radiosurgery was safe and effective and achieved complete AVM obliteration in about 80% of cases. The most prominent predictors of AVM success included AVM size, AVM volume, radiation dose, number of draining veins and patient age.

Volume-Staged Gamma Knife Radiosurgery for Large Brain Arteriovenous Malformation

OBJECTIVE

Large brain arteriovenous malformations (AVMs) pose a management dilemma because of the limited success of any single treatment modality by itself. Surgery alone is associated with significant morbidity and mortality. Similarly, embolization alone has limited efficacy. Volume-staged Gamma Knife radiosurgery (VSGR) has been developed for the treatment of large AVMs to increase the efficacy and improve safety of treatment of these lesions. The aim of this study was to assess the efficacy and safety of VSGR technique for the treatment of large brain AVMs.

METHODS

The study included patients treated by VSGR between May 2009 and July 2015. All patients had large AVMs (>10 mL). There were 29 patients.

RESULTS

Twenty-four patients completed radiographic follow-up, with 15 obliteration cases (62.5%). A total of 56 sessions were performed. The mean AVM volume was 16 mL (range, 10.1-29.3 mL). The mean prescription dose was 18 Gy (range, 14-22 Gy). The mean follow-up duration was 43 months (range, 21-73 months). One patient died during follow-up of an unrelated cause. Two patients had hemorrhage during follow-up. Symptomatic edema developed in 5 patients (17%). The factors affecting obliteration were smaller total volume, higher dose/stage, nondeep location, compact AVM, AVM score <3, >18 Gy dose, and <15 mL total volume. The factors affecting symptomatic edema were smaller total volume and shorter time between first and last sessions (P = 0.012). T2 image changes were affected by Spetzler-Martin grade ≥3 (P = 0.013) and AVM score ≥3 (P = 0.014).

CONCLUSIONS

VSGR provides an effective and safe treatment option for large brain AVMs. Smaller AVM volume is associated with higher obliteration rate.

Multimodal management of arteriovenous malformations of the basal ganglia and thalamus: factors affecting obliteration and outcome

OBJECTIVE

Arteriovenous malformations (AVMs) of the basal ganglia and thalamus are particularly difficult lesions to treat, accounting for 3%-13% of all AVMs in surgical series and 23%-44% of malformations in radiosurgery series. The goal of this study was to report the results of multimodal management of basal ganglia and thalamic AVMs and investigate the factors that influence radiographic cure and good clinical outcomes.

METHODS

This study was a retrospective analysis of a prospectively maintained database of all patients treated at the authors' institution. Clinical, radiological, follow-up, and outcome data were analyzed. Univariate and multivariate analyses were conducted to explore the influence of various factors on outcome.

RESULTS

The results and data analysis pertaining to 123 patients treated over 32 years are presented. In this cohort, radiographic cure was achieved in 50.9% of the patients. Seventy-five percent of patients had good clinical outcomes (stable or improved performance scores), whereas 25% worsened after treatment. Inclusion of surgery and radiosurgery independently predicted obliteration, whereas nidus diameter and volume predicted clinical outcomes. Nidus volume/diameter and inclusion of surgery predicted the optimal outcome, i.e., good clinical outcomes with lesion obliteration.

CONCLUSIONS

Good outcomes are possible with multimodal treatment in these complex patients. Increasing size and, by extension, higher Spetzler-Martin grade are associated with worse outcomes. Inclusion of multiple modalities of treatment as indicated could improve the chances of radiographic cure and good outcomes.

Clinical outcome of brainstem arteriovenous malformations after incomplete nidus obliteration

PURPOSE

Brainstem arteriovenous malformations (AVMs) present a formidable therapeutic challenge, and a variety of surgical and non-surgical treatment strategies can be used to obliterate the AVM nidus, eliminating its risk of hemorrhage. However, complete obliteration of brainstem AVMs is often not possible. We aimed to investigate the natural history of brainstem AVMs with incomplete nidus obliteration after initial treatment.

METHODS

Data from consecutive patients who presented to our institution during the study period with a brainstem AVM and residual nidus after treatment were retrospectively reviewed. We evaluated patients for the incidence of AVM rupture and calculated the risk of rupture after treatment resulted in incomplete nidus obliteration.

RESULTS

A total of 14 patients were included, five of whom suffered rupture after incomplete nidus obliteration (36%). Annual risk of rupture was 4.9% (95% CI: 1.60-11.5) per patient over a median follow-up of 72 months. The most common treatment modality of these patients was SRS-alone (n = 6), and two (33%) patients who underwent this treatment later ruptured after 103 and 130 months. Of the five patients who ruptured after treatment, 80% had already ruptured once, and 80% had an intranidal and/or feeding artery aneurysm.

CONCLUSIONS

Brainstem AVMs with incomplete nidus obliteration are at high risk of future rupture. Patients with brainstem AVMs who have a residual nidus after treatment should be counselled about the risk of AVM rupture and be recommended to undergo close follow-up imaging studies to monitor the nidus.

Does Advanced Age Affect the Outcomes of Stereotactic Radiosurgery for Cerebral Arteriovenous Malformation?

BACKGROUND

Stereotactic radiosurgery (SRS) is generally considered a minimally invasive treatment modality. However, definitive evidence of the efficacy of SRS in the elderly population is still not available.

METHODS

The outcomes of 561 elderly and nonelderly patients who underwent SRS for AVM at our institution between 1990 and 2013 were reviewed, analyzed, and compared. Elderly patients were defined as those age ≥60 years at the time of SRS.

RESULTS

The elderly cohort comprised 55 patients; the nonelderly cohort, 506. In the elderly cohort, the median age was 65 years, and the duration of follow-up was 91 months. The actuarial obliteration rates were 47% at 3 years, 70% at 4 years, and 76% at 5 years in the elderly cohort, and 57% at 3 years, 76% at 4 years, and 83% at 5 years in the nonelderly cohort. In the elderly cohort, the hemorrhage rates during the post-SRS latent phase were 5.2%/year in patients with hemorrhagic onset and 0%/year in those with nonhemorrhagic onset, and event-free survival (EFS) was 93% at 6 years and 89% at 12 years. The obliteration rate, mortality, and EFS rate were not significantly different between the 2 cohorts, whereas the rate of perifocal edema was significantly lower (P = 0.021) in the elderly cohort. The pre-SRS and post-SRS hemorrhage rates were slightly higher in the elderly cohort, albeit without statistical significance.

CONCLUSIONS

Therapeutic effects and outcomes of SRS are similar in elderly and nonelderly patients. Treatment-related neurologic deficits are rare, and longer EFS can be expected.

A proposed grading system to evaluate the endovascular curability of deep-seated arteriovenous malformations

BACKGROUND

Aggressive treatment of deep-seated AVMs is paramount because of their high tendency to bleed (or to re-bleed). In the literature concerning endovascular therapy, AVMs of the basal ganglia, the semi-ovale center and the midbrain are always considered as a single entity. In this study, the authors address the anatomical classification of these AVMs and propose a classification that considers factors influencing their endovascular curability.

METHODS

From 1995 to 2013, clinical and angiographic data of cerebral AVMs were prospectively collected. We reviewed data from patients treated for a deep-seated AVM with the goal to distinguish factors that influence the curability and the outcome of these AVMs.

RESULTS

134 patients (mean age: 28years) were consecutively treated by endovascular techniques. We describe an anatomical classification concerning the exact location of the nidus and distinguish 5 different sub-types (anterior, lateral, medial, posterior and midbrain). Then, we propose a grading system based on statistical analysis of our series to evaluate the curability of a deep AVM. This comprehensive score is calculated with the Spetzler-Martin grade, the location of the nidus, its type, arterial feeders and venous drainage.

CONCLUSIONS

Deep-seated AVMs may be classified according to their exact location; we can distinguish 5 different sub-types (anterior, lateral, medial, posterior and midbrain). Each group presented different arterial supplies and venous drainage that influenced treatment possibilities. The comprehensive grading system that we propose in this study must be tested in another deep-seated AVMs population.

Staged-Volume Radiosurgery of Large Arteriovenous Malformations Improves Outcome by Reducing the Rate of Adverse Radiation Effects

BACKGROUND: The treatment of large arteriovenous malformations (AVMs) remains challenging. Recently, staged-volume radiosurgery (SVRS) has become an option.

OBJECTIVE: To compare the outcome of SVRS on large AVMs with our historical, single-stage radiosurgery (SSRS) series.

METHODS: We have been prospectively collecting data of patients treated by SVRS since 2007. There were 84 patients who had a median age of 37 years (range, 9-62 years) who were treated until July 2013. The outcomes of 76 of those who had follow-ups available were analyzed and compared with the outcomes of 122 patients treated with the best SSRS technique.

RESULTS: There were 21.5% of AVMs that were deep seated, and 44% presented with hemorrhage resulting in 45% fixed neurological deficit. There were 14% of patients who had undergone embolization before radiosurgery. The median nidus treatment volume was 19.7 cm3 (6.65-68.7) and 17.5 Gy (13-22.5) prescription isodose was given. Of the 44 lesions having radiological follow-up at 4 years, 61.4% were completely obliterated. Previous embolization (50% with and 63% without) and higher Spetzler-Martin grades appeared to be the negative factors in successful obliteration, but treatment volume was not. Within 3 years after radiosurgery, the annual bleed rates of unruptured and previously ruptured AVMs were 3.2% and 5.6%, respectively. Three bleeds were fatal and 2 resulted in significant modified Rankin scale 3 morbidity. These rates differ little from SSRS. Temporary adverse radiation effects (AREs) did not change significantly, but permanent AREs dropped from 15% to 6.5% (P = .03) compared with SSRS.

CONCLUSION: Obliteration and hemorrhage rates of large AVMs treated by SVRS are similar to historical SSRS. However, SVRS offers a lower rate of AREs.

Comparative analysis of arteriovenous malformation grading scales in predicting outcomes after stereotactic radiosurgery

OBJECTIVE Successful stereotactic radiosurgery (SRS) for the treatment of arteriovenous malformations (AVMs) results in nidus obliteration without new neurological deficits related to either intracranial hemorrhage (ICH) or radiation-induced complications (RICs). In this study the authors compared 5 AVM grading scales (Spetzler-Martin grading scale, radiosurgery-based AVM score [RBAS], Heidelberg score, Virginia Radiosurgery AVM Scale [VRAS], and proton radiosurgery AVM scale [PRAS]) at predicting outcomes after SRS. METHODS The study group consisted of 381 patients with sporadic AVMs who underwent Gamma Knife SRS between January 1990 and December 2009; none of the patients underwent prior radiation therapy. The primary end point was AVM obliteration without a decline in modified Rankin Scale (mRS) score (excellent outcome). Comparison of the area under the receiver operating characteristic curve (AUC) and accuracy was performed between the AVM grading scales and the best linear regression model (generalized linear model, elastic net [GLMnet]). RESULTS The median radiological follow-up after initial SRS was 77 months; the median clinical follow-up was 93 months. AVM obliteration was documented in 297 patients (78.0%). Obliteration was 59% at 4 years and 85% at 8 years. Fifty-five patients (14.4%) had a decline in mRS score secondary to RICs (n = 29, 7.6%) or ICH (n = 26, 6.8%). The mRS score declined by 10% at 4 years and 15% at 8 years. Overall, 274 patients (71.9%) had excellent outcomes. There was no difference between the AUC for the GLMnet (0.69 [95% CI 0.64-0.75]), RBAS (0.68 [95% CI 0.62-0.74]), or PRAS (0.69 [95% CI 0.62-0.74]). Pairwise comparison for accuracy showed no difference between the GLMnet and the RBAS (p = 0.08) or PRAS (p = 0.16), but it did show a significant difference between the GLMnet and the Spetzler-Martin grading system (p < 0.001), Heidelberg score (p < 0.001), and the VRAS (p < 0.001). The RBAS and the PRAS were more accurate when compared with the Spetzler-Martin grading scale (p = 0.03 and p = 0.01), Heidelberg score (p = 0.02 and p = 0.02), and VRAS (p = 0.03 and p = 0.02). CONCLUSIONS SRS provides AVM obliteration without functional decline in the majority of treated patients. AVM grading scales having continuous scores (RBAS and PRAS) outperformed integer-based grading systems in the prediction of AVM obliteration without mRS score decline after SRS.

Stereotactic Radiosurgery for Arteriovenous Malformations

BACKGROUND:

Stereotactic radiosurgery (SRS) has been performed on patients with cerebral arteriovenous malformations (AVMs) for over 40 years.

OBJECTIVE:

To evaluate the impact of treatment period on obliteration, intracranial hemorrhage (ICH), and radiation-induced complications (RICs).

METHODS:

Retrospective comparison of 381 AVM patients having SRS during a 20-year period (group 1, January 1990 through March 1997, n = 160; group 2, April 1997 through December 2009, n = 221). The median radiological and clinical follow-up after initial SRS was 77 months and 93 months, respectively.

RESULTS:

Obliteration was 59.1% at 4 years and 85.1% at 8 years. Obliteration was more common in patients with hemispheric or cerebellar AVMs (P = .001), smaller prescription isodose volume (PIV) (P &lt; .001), and group 1 patients (P &lt; .001). The ICH rate was 7.7% at 4 years and 10.6% at 8 years. ICH was more common in older patients (P = .02), patients with deep AVM (P = .01), and larger PIV (P &lt; .001). There was no difference in the ICH rate between the treatment groups (P = .18). The rate of permanent RICs was 4.4% at 4 years and 8.6% at 8 years. RICs were more common with larger PIVs (P &lt; .001) and group 1 patients (P = .02). There was no difference in the number of patients having obliteration without new deficits between the 2 treatment periods (68.8% vs 73.3%, P = .33).

CONCLUSION:

Advances in SRS procedures over the past 20 years have resulted in a lower risk of RIC, but fewer patients had AVM obliteration. Increasing the prescription dose for patients with medium- and large-volume AVMs by using current conformal dose-planning techniques may improve the obliteration rate while maintaining a low risk of RICs.

Repeat radiosurgery for cerebral arteriovenous malformations

We perform a systematic review of repeat radiosurgery for cerebral arteriovenous malformations (AVM) with an emphasis on lesion obliteration rates and complications. Radiosurgery is an accepted treatment modality for AVM located in eloquent cortex or deep brain structures. For residual or persistent lesions, repeat radiosurgery can be considered if sufficient time has passed to allow for a full appreciation of treatment effects, usually at least 3years. A systematic review was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. References for this review were identified by searches of MEDLINE, Web of Science and Google Scholar databases. A total of 14 studies comprising 733 patients met the review criteria and were included. For series that reported target dose at both first and repeat treatments, the weighted means were 19.42Gy and 19.06Gy, respectively. The mean and median obliteration rate for the repeat radiosurgery treatments were 61% (95% confidence interval 51.9-71.7%) and 61.5%, respectively. The median follow up following radiosurgery ranged from 19.5 to 80months. Time to complete obliteration after the repeat treatment ranged from 21 to 40.8months. The most common complications of repeat radiosurgery for AVM included hemorrhage (7.6%) and radiation-induced changes (7.4%). Repeat radiosurgery can be used to treat incompletely obliterated AVM with an obliteration rate of 61%. Complications are related to treatment effect latency (hemorrhage risk) as well as radiation-induced changes. Repeat radiosurgery can be performed at 3 years following the initial treatment, allowing for full realization of effects from the initial treatment prior to commencing therapy.

Stereotactic radiosurgery for arteriovenous malformations of the postgeniculate visual pathway

OBJECT

A visual field deficit resulting from the management of an arteriovenous malformation (AVM) significantly impacts a patient's quality of life. The present study was designed to investigate the clinical and radiological outcomes of stereotactic radiosurgery (SRS) performed for AVMs involving the postgeniculate visual pathway.

METHODS

In this retrospective single-institution analysis, the authors reviewed their experience with Gamma Knife surgery for postgeniculate visual pathway AVMs performed during the period between 1987 and 2009.

RESULTS

During the study interval, 171 patients underwent SRS for AVMs in this region. Forty-one patients (24%) had a visual deficit prior to SRS. The median target volume was 6.0 cm3 (range 0.4–22 cm3), and 19 Gy (range 14–25 Gy) was the median margin dose. Obliteration of the AVM was confirmed in 80 patients after a single SRS procedure at a median follow-up of 74 months (range 5–297 months). The actuarial rate of total obliteration was 67% at 4 years. Arteriovenous malformations with a volume < 5 cm3 had obliteration rates of 60% at 3 years and 79% at 4 years. The delivered margin dose proved significant given that 82% of patients receiving ≥ 22 Gy had complete obliteration. The AVM was completely obliterated in an additional 18 patients after they underwent repeat SRS. At a median of 25 months (range 11–107 months) after SRS, 9 patients developed new or worsened visual field deficits. One patient developed a complete homonymous hemianopia, and 8 patients developed quadrantanopias. The actuarial risk of sustaining a new visual deficit was 3% at 3 years, 5% at 5 years, and 8% at 10 years. Fifteen patients had hemorrhage during the latency period, resulting in death in 9 of the patients. The annual hemorrhage rate during the latency interval was 2%, and no hemorrhages occurred after confirmed obliteration.

CONCLUSIONS

Despite an overall treatment mortality of 5%, related to latency interval hemorrhage, SRS was associated with only a 5.6% risk of new visual deficit and a final obliteration rate close to 80% in patients with AVMs of the postgeniculate visual pathway.

Gamma Knife surgery for arteriovenous malformations within or adjacent to the ventricles

Object

The outcomes of stereotactic radiosurgery for arteriovenous malformations (AVMs) within or adjacent to the ventricular system are largely unknown. This study assessed the long-term outcomes and hemorrhage risks for patients with AVMs within this region who underwent Gamma Knife surgery (GKS) at the University of Pittsburgh.

Methods

The authors retrospectively identified 188 patients with ventricular-region AVMs who underwent a single-stage GKS procedure during a 22-year interval. The median patient age was 32 years (range 3–80 years), the median target volume was 4.6 cm3 (range 0.1–22 cm3), and the median marginal dose was 20 Gy (range 13–27 Gy).

Results

Arteriovenous malformation obliteration was confirmed by MRI or angiography in 89 patients during a median follow-up of 65 months (range 2–265 months). The actuarial rates of total obliteration were 32% at 3 years, 55% at 4 years, 60% at 5 years, and 64% at 10 years. Higher rates of AVM obliteration were obtained in the 26 patients with intraventricular AVMs. Twenty-five patients (13%) sustained a hemorrhage during the initial latency interval after GKS, indicating an annual hemorrhage rate of 3.4% prior to AVM obliteration. No patient experienced a hemorrhage after AVM obliteration was confirmed by imaging. Permanent neurological deficits due to adverse radiation effects developed in 7 patients (4%).

Conclusions

Although patients in this study demonstrated an elevated hemorrhage risk that remained until complete obliteration, GKS still proved to be a generally safe and effective treatment for patients with these high-risk intraventricular and periventriclar AVMs.

Safety and efficacy using a detachable tip microcatheter in the embolization of pediatric arteriovenous malformations

PURPOSE

The treatment of deep-seeded pediatric brain arteriovenous malformations (AVMs) remains a challenging task. We describe our experience using a new detachable tip microcatheter in the embolization of brain arteriovenous malformations, pial arteriovenous fistulas, and vein of Galen malformations. We describe the safety and efficacy using a new detachable tip microcatheter in the treatment of pediatric deep brain arteriovenous malformations, pial malformations, and vein of Galen malformations.

METHODS

During a period of 9 months from March 2013 through January 2014, 11 pediatric patients in 14 procedures with 27 total injections were selected for treatment with a detachable tip under Food and Drug Administration (FDA) compassionate use exemption and were admitted to our department for treatment of their brain AVM using a liquid embolic agent and a detachable tip microcatheter. The ages of the patients ranged from 3 months to 18 years old.

RESULTS

Of the 27 total injections done, the tip detached in seven cases. For the 16 n-BCA injections, the tip detached six times (37.5 %), and for the 11 Onyx injections, the tip detached one time (9 %). There were no cases of premature microcatheter detachment during normal vessel navigation.

CONCLUSIONS

The introduction of these detachable tip microcatheters allows for a safe and relaxed injection that permits a true circumferential occlusion, and may further permit filling a larger amount of angioarchitecture without the risk of distal migration, or vessel damage during the usual rapid removal of non detachable micocatheters.

Deep arteriovenous malformations in the Basal Ganglia, thalamus, and insula: microsurgical management, techniques, and results

BACKGROUND

Arteriovenous malformations (AVMs) in the basal ganglia, thalamus, and insula are considered inoperable given their depth, eloquence, and limited surgical exposure. Although many neurosurgeons opt for radiosurgery or observation, others have challenged the belief that deep AVMs are inoperable. Further discussion of patient selection, technique, and multimodality management is needed.

OBJECTIVE

To describe and discuss the technical considerations of microsurgical resection for deep-seated AVMs.

METHODS

Patients with deep AVMs who underwent surgery during a 14-year period were reviewed through the use of a prospective AVM registry.

RESULTS

Microsurgery was performed in 48 patients with AVMs in the basal ganglia (n=10), thalamus (n=13), or insula (n=25). The most common Spetzler-Martin grade was III- (68%). Surgical approaches included transsylvian (67%), transcallosal (19%), and transcortical (15%). Complete resection was achieved in 34 patients (71%), and patients with incomplete resection were treated with radiosurgery. Forty-five patients (94%) were improved or unchanged (mean follow-up, 1.6 years).

CONCLUSION

This experience advances the notion that select deep AVMs may be operable lesions. Patients were highly selected for small size, hemorrhagic presentation, young age, and compactness-factors embodied in the Spetzler-Martin and Supplementary grading systems. Overall, 10 different approaches were used, exploiting direct, transcortical corridors created by hemorrhage or maximizing anatomic corridors through subarachnoid spaces and ventricles that minimize brain transgression. The same cautious attitude exercised in selecting patients for surgery was also exercised in deciding extent of resection, opting for incomplete resection and radiosurgery more than with other AVMs to prioritize neurological outcomes.

Deep arteriovenous malformations in the basal ganglia, thalamus, and insula: multimodality management, patient selection, and results

OBJECTIVE

This study sought to describe a single institution's experience treating arteriovenous malformations (AVMs) of the basal ganglia, thalamus, and insula in a multimodal fashion.

METHODS

We conducted a retrospective review of all deep AVMs treated at our institution between 1997 and 2011 with attention to patient selection, treatment strategies, and radiographic and functional outcomes.

RESULTS

A total of 97 patients underwent initial treatment at our institution. 64% presented with hemorrhage with 29% located in the basal ganglia, 41% in the thalamus, and 30% in the insula. 80% were Spetzler-Martin grade III-IV. Initial treatment was microsurgical resection in 42%, stereotactic radiosurgery (SRS) in 45%, and observation in 12%. Radiographic cure was achieved in 54% after initial surgical or SRS treatment (71% and 23%, respectively) and in 63% after subsequent treatments, with good functional outcomes in 78% (median follow-up 2.2 years). Multivariate logistic regression analysis revealed treatment group and age as factors associated with radiographic cure, whereas Spetzler-Martin score and time to follow-up were significantly associated with improved/unchanged functional status at time of last follow-up. Posttreatment hemorrhage occurred in 11% (7% of surgical and 18% of SRS patients).

CONCLUSIONS

Modern treatment of deep AVMs includes a multidisciplinary approach utilizing microsurgery, SRS, embolization, and observation. Supplementary grading adds meaningfully to traditional Spetzler-Martin grading to guide patient selection. Surgical resection is more likely to result in obliteration compared with SRS, and is associated with satisfactory results in carefully selected patients.

Stereotactic radiosurgery for arteriovenous malformations of the cerebellum

Object

Arteriovenous malformations (AVMs) of the posterior fossa have an aggressive natural history and propensity for hemorrhage. Although the cerebellum accounts for the majority of the posterior fossa volume, there is a paucity of stereotactic radiosurgery (SRS) outcome data for AVMs of this region. The authors sought to evaluate the long-term outcomes and risks of cerebellar AVM radiosurgery.

Methods

This single-institution retrospective analysis reviewed the authors' experience with Gamma Knife surgery during the period 1987–2007. During this time 64 patients (median age 47 years, range 8–75 years) underwent SRS for a cerebellar AVM. Forty-seven patients (73%) presented with an intracranial hemorrhage. The median target volume was 3.85 cm3 (range 0.2–12.5 cm3), and the median marginal dose was 21 Gy (range 15–25 Gy).

Results

Arteriovenous malformation obliteration was confirmed by MRI or angiography in 40 patients at a median follow-up of 73 months (range 4–255 months). The actuarial rates of total obliteration were 53% at 3 years, 69% at 4 years, and 76% at 5 and 10 years. Elevated obliteration rates were statistically higher in patients who underwent AVM SRS without prior embolization (p = 0.005). A smaller AVM volume was also associated with a higher rate of obliteration (p = 0.03). Four patients (6%) sustained a hemorrhage during the latency period and 3 died. The cumulative rates of AVM hemorrhage after SRS were 6% at 1, 5, and 10 years. This correlated with an overall annual hemorrhage rate of 2.0% during the latency interval. One patient experienced a hemorrhage 9 years after confirmed MRI and angiographic obliteration. A permanent neurological deficit due to adverse radiation effects developed in 1 patient (1.6%) and temporary complications were seen in 2 additional patients (3.1%).

Conclusions

Stereotactic radiosurgery proved to be most effective for patients with smaller and previously nonembolized cerebellar malformations. Hemorrhage during the latency period occurred at a rate of 2.0% per year until obliteration occurred.

Microsurgical management of deep ruptured arteriovenous malformations of the basal ganglia and thalamus

Introduction : Deep AVMs are more difficult to operate compared with other supratentorial locations due to the long working corridor through the brain, location in eloquent areas and vicinity with brain critical structures.

Material and Method : We report a series of 7 cases with deep AVMs operated in the Fourth Department of Neurosurgery, Emergency Clinical Hospital Bagdasar-Arseni, between 2009 and 2013.

Results : Six patients had ruptured AVMs and one presented frequent, refractory seizures due to a deep large porencephalic cyst. At admission, one patient presented mRS 2, 3 patients had mRS 4 and 3 patients had mRS 5. Patients underwent surgery and we achieved total resection in 5 patients and we left a residual nidus in two cases. These last 2 patients with residual nidus were referred to stereotactic radiosurgery Gamma Knife with good results. Following surgery mRS improved in all 7 patients, 3 had mRS 1, 3 had mRS 3 and one mRS 4. Outcome was favorable in 3 cases and slowly favorable in 4 patients.

Conclusions : Deep AVMs frequently present sudden onset, with altered mental state, motor deficits and large intraparenchymatal hematomas. Surgery is mandatory for deep ruptured AVMs, being the only treatment that can provide neurological improvement through hematoma evacuation and cure through nidus resection. In experienced hands, deep AVMs can be successfully resected. Postoperative results are good, with improvement of state of consciousness and motor deficits. Adequate patient selection is essential in order to achieve a good postoperative outcome.

Long-term outcomes of gamma knife surgery for posterior fossa arteriovenous malformations

The long-term outcomes of gamma knife surgery (GKS) in patients with posterior fossa arteriovenous malformations (AVMs) were retrospectively analyzed in 82 patients followed up for more than 5 years to evaluate the efficacy and safety. The median AVM volume at GKS was 0.95 cm³. The prescribed dose to the AVM margin was median 18 Gy with 1–18 isocenters. The actual complete AVM obliteration rate was 58.5% at 3 years and 78.0% at 5 years. The significant factors for higher complete obliteration rate were younger patient age and smaller maximum/minimum nidus diameter ratio. Two patients experienced hemorrhage caused by residual AVM rupture at 4 and 49 months. Twenty patients developed peri-nidal edema as an adverse radiation-induced reaction at median 13 months. One patient developed radiation-induced necrosis at 6.8 years. Neurological complication was observed in 12 patients and 6 patients remained with neurological dysfunction permanently. Larger nidus volume and location adjacent to an eloquent area significantly increased the risk of neurological complication. Pittsburgh radiosurgery-based AVM grading scale was significantly correlated with the outcome of neurological symptoms after GKS. GKS achieved acceptable and complete obliteration rate for posterior fossa AVM with relatively low risk of morbidity on neuroimaging and neurological symptoms for the long-term period after treatment. We recommend conformable and selective treatment planning to achieve both obliteration of the AVM nidus and preservation of neurological function.