Radiosurgical Retreatment for Brain Arteriovenous Malformation

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.

LINAC stereotactic radiosurgery for brain arteriovenous malformations: An updated single centre analysis of outcomes

Arteriovenous malformations (AVM) of the brain are congenital, high pressure vascular malformations, which are at risk of haemorrhage. Stereotactic radiosurgery (SRS) can obliterate the nidus by delivering a precise high dose of ionising radiation in a single fraction. This paper updates long term AVM obliteration rates, time to obliteration and retreatment outcomes in LINAC delivered SRS treatment at the Royal Adelaide Hospital. A retrospective review of a prospectively maintained AVM SRS database supplemented by clinical case notes, patient correspondence and electronic medical records was performed. 89 AVMs received primary SRS treatment for which the crude obliteration rate was 61% (68% for 79 patients with adequate follow up). Higher marginal dose, smaller nidus size and lower Pollock-Flickinger (PF) score were significantly associated with AVM obliteration. The crude obliteration rates for patients with adequate follow-up and AVM diameter < 3 cm vs ≥ 3 cm were 76% vs 48%, respectively, and 93% with PF score < 1.0. Median time to obliteration was 36 months. Higher dose and lower PF score were associated with earlier obliteration. The crude obliteration rate after second SRS was 56% (9/16 patients) and no significant associations were found. These obliteration rates after primary and retreatment LINAC SRS are comparable to other studies. Marginal dose and PF score were the main predictors of obliteration overall as well as early (<36 months) obliteration.

Quantification of hemodynamics of cerebral arteriovenous malformations after stereotactic radiosurgery using 4D flow magnetic resonance imaging

Stereotactic radiosurgery (SRS) is used to treat cerebral arteriovenous malformations (AVMs). However, early evaluation of efficacy is difficult as structural magnetic resonance imaging (MRI)/magnetic resonance angiography (MRA) often does not demonstrate appreciable changes within the first 6 months. The aim of this study was to evaluate the use of four-dimensional (4D) flow MRI to quantify hemodynamic changes after SRS as early as 2 months. This was a retrospective observational study, which included 14 patients with both pre-SRS and post-SRS imaging obtained at multiple time points from 1 to 27 months after SRS. A 3T MRI Scanner was used to obtain T₂ single-shot fast spin echo, time-of-flight MRA, and postcontrast 4D flow with three-dimensional velocity encoding between 150 and 200 cm/s. Post-hoc two-dimensional cross-sectional flow was measured for the dominant feeding artery, the draining vein, and the corresponding contralateral artery as a control. Measurements were performed by two independent observers, and reproducibility was assessed. Wilcoxon signed-rank tests were used to compare differences in flow, circumference, and pulsatility between the feeding artery and the contralateral artery both before and after SRS; and differences in nidus size and flow and circumference of the feeding artery and draining vein before and after SRS. Arterial flow (L/min) decreased in the primary feeding artery (mean: 0.1 ± 0.07 vs. 0.3 ± 0.2; p < 0.05) and normalized in comparison to the contralateral artery (mean: 0.1 ± 0.07 vs. 0.1 ± 0.07; p = 0.068). Flow decreased in the draining vein (mean: 0.1 ± 0.2 vs. 0.2 ± 0.2; p < 0.05), and the circumference of the draining vein also decreased (mean: 16.1 ± 8.3 vs. 15.7 ± 6.7; p < 0.05). AVM volume decreased after SRS (mean: 45.3 ± 84.8 vs. 38.1 ± 78.7; p < 0.05). However, circumference (mm) of the primary feeding artery remained similar after SRS (mean: 15.7 ± 2.7 vs. 16.1 ± 3.1; p = 0.600). 4D flow may be able to demonstrate early hemodynamic changes in AVMs treated with radiosurgery, and these changes appear to be more pronounced and occur earlier than the structural changes on standard MRI/MRA. Level of Evidence: 4 Technical Efficacy Stage: 1.

Outcome of cerebral arteriovenous malformations after linear accelerator reirradiation

Background:

The aim of this study was to evaluate the clinical outcome of patients undergoing single-dose reirradiation using the Linear Accelerator (LINAC) for brain arteriovenous malformations (AVM).

Methods:

A retrospective study of 37 patients with brain AVM undergoing LINAC reirradiation between April 2003 and November 2011 was carried out. Patient characteristics, for example, gender, age, use of medications, and comorbidities; disease characteristics, for example, Spetzler–Martin grading system, location, volume, modified Pollock–Flickinger score; and treatment characteristics, for example, embolization, prescription dose, radiation dose–volume curves, and conformity index were analyzed. During the follow-up period, imaging studies were performed to evaluate changes after treatment and AVM cure. Complications, such as edema, rupture of the blood–brain barrier, and radionecrosis were classified as symptomatic and asymptomatic.

Results:

Twenty-seven patients underwent angiogram after reirradiation and the percentage of angiographic occlusion was 55.5%. In three patients without obliteration, AVM shrinkage made it possible to perform surgical resection with a 2/3 cure rate. A reduction in AVM nidus volume greater than 50% after the first procedure was shown to be the most important predictor of obliteration. Another factor associated with AVM cure was a prescription dose higher than 15.5 Gy in the first radiosurgery. Two patients had permanent neurologic deficits. Factors correlated with complications were the prescription dose and maximum dose in the first procedure.

Conclusion:

This study suggests that single-dose reirradiation is safe and feasible in partially occluded AVM. Reirradiation may not benefit candidates whose prescribed dose was lower than 15.5 Gy in the first procedure and initial AVM nidus volume did not decrease by more than 50% before reirradiation.

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.

Gamma Knife for Cerebral Arteriovenous Malformations at a Single Centre

Background:

We report the results of a consecutive series of patients treated with Gamma Knife (GK) Surgery for cerebral arteriovenous malformations (AVMs).

Methods:

We retrospectively reviewed 69 patients treated with GK for cerebral AVMs between November 2003 and April 2009, recording clinical data, treatment parameters, and AVM obliteration rates in order to assess our effectiveness with GK in treating these lesions.

Results:

Ten patients were lost to follow-up. Presentations included: seizure (24), hemorrhage (18), persistent headache (12), progressing neurological signs (10), and incidental (9). In 24 patients (34.8%) treatment planning consisted of digital subtraction angiography (DSA), magnetic resonance imaging (MRI), and computed tomogram (CT) angiography (CTA). Currently we rely predominantly on CTA and/or MRI scanning only. Fourty-one patients have been followed for a minimum of 3 years; average age 40.9yr., 58.5% males. Average dose at the 50% isodose line was 20.3 Gy (range 16 to 26.4 Gy). Obliteration was observed in 87.8% by MRI, CT, or DSA. Not all obliteration was confirmed by DSA. Complications occurred in 12 of 59 (20.3%) patients, and in 11 of 41 (26.8%) with 3 year follow-up. Major (temporary) complications for the 59 included symptomatic cerebral edema (7), seizure (2), and hemorrhage (1). Major permanent complications occurred in one patient suffering a cranial nerve V deafferentation, and in two patients suffering a hemorrhage.

Conclusion:

GKS for cerebral AVM's offers an effective and safe method of treatment, with low permanent complication rate.

Stereotactic radiosurgery of intracranial arteriovenous malformations

Stereotactic radiosurgery for intracranial arteriovenous malformations (AVMs) has been performed since the 1970s. When an AVM is treated with radiosurgery, radiation injury to the vascular endothelium induces the proliferation of smooth muscle cells and the elaboration of extracellular collagen, which leads to progressive stenosis and obliteration of the AVM nidus. Obliteration after AVM radiosurgery ranges from 60% to 80%, and relates to the size of the AVM and the prescribed radiation dose. The major drawback of radiosurgical AVM treatment is the risk of bleeding during the latent period (typically 2 years) between treatment and AVM thrombosis.

Dynamic radiosurgery at the Toronto - Bayview Regional Cancer Centre, 1988-2007

Dynamic radiosurgery was first developed in Montreal and was subsequently adopted at the Toronto-Bayview Regional Cancer Centre in 1988. At that time radiosurgery was in its infancy in Canada. The opportunity of offering highly conformal radiation treatments for intracranial targets presented numerous technical challenges notably in the area of quality assurance. This review chronicles the development of radiosurgery at the Toronto-Bayview Regional Cancer Centre and summarises the successes and failures of the program over the following two decades.

Radiosurgery for arteriovenous malformations

Stereotactic radiosurgery is the term coined by Lars Leksell to describe the application of a single, high dose of radiation to a stereotactically defined target volume. In the 1970s, reports began to appear documenting the successful obliteration of arteriovenous malformations (AVMs) with radiosurgery. When an AVM is treated with radiosurgery, a pathologic process appears to be induced that is similar to the response-to-injury model of atherosclerosis. Radiation injury to the vascular endothelium is believed to induce the proliferation of smooth-muscle cells and the elaboration of extracellular collagen, which leads to progressive stenosis and obliteration of the AVM nidus thereby eliminating the risk of hemorrhage. The advantages of radiosurgery - compared to microsurgical and endovascular treatments - are that it is noninvasive, has minimal risk of acute complications, and is performed as an outpatient procedure requiring no recovery time for the patient. The primary disadvantage of radiosurgery is that cure is not immediate. While thrombosis of the lesion is achieved in the majority of cases, it commonly does not occur until two or three years after treatment. During the interval between radiosurgical treatment and AVM thrombosis, the risk of hemorrhage remains. Another potential disadvantage of radiosurgery is possible long term adverse effects of radiation. Finally, radiosurgery has been shown to be less effective for lesions over 10 cc in volume. For these reasons, selection of the optimal treatment for an AVM is a complex decision requiring the input of experts in endovascular, open surgical, and radiosurgical treatment. In the pages below, we will review the world's literature on radiosurgery for AVMs. Topics reviewed will include the following: radiosurgical technique, radiosurgery results (gamma knife radiosurgery, particle beam radiosurgery, linear accelerator radiosurgery), hemorrhage after radiosurgery, radiation induced complications, repeat radiosurgery, and radiosurgery for other types of vascular malformation.

Repeat Gamma Knife Surgery for Incompletely Obliterated Cerebral Arteriovenous Malformations

OBJECTIVE

The causes of failure after an initial Gamma procedure were studied, along with imaging and clinical outcomes, in a series of 140 patients with cerebral arteriovenous malformations (AVMs) treated with repeat Gamma Knife surgery (GKS).

METHODS

Causes of initial treatment failure included inaccurate nidus definition in 14 patients, failure to fill part of the nidus as a result of hemodynamic factors in 16, recanalization of embolized AVM compartments in 6, and suboptimal dose (&lt; 20 Gy) in 23. Nineteen patients had repeat GKS for subtotal obliteration of AVMs. In 62 patients, the AVM failed to obliterate despite correct target definition and adequate dose. At the time of retreatment, the nidus volume ranged from 0.1 to 6.9 cm3 (mean, 1.4 cm3), and the mean prescription dose was 20.3 Gy.

RESULTS

Repeat GKS yielded a total angiographic obliteration in 77 patients (55%) and subtotal obliteration in 9 (6.4%). In 38 patients (27.1%), the AVMs remained patent, and in 16 patients (11.4%), no flow voids were observed on magnetic resonance imaging. Clinically, 126 patients improved or remained stable, and 14 experienced deterioration (8 resulting from a rebleed, 2 caused by persistent arteriovenous shunting, and 4 related to radiation-induced changes).

CONCLUSION

By using repeat GKS, we achieved a 55% angiographic cure rate. Although radiation-induced changes as visualized on magnetic resonance imaging occurred in 48 patients (39%), only 4 patients (3.6%) developed permanent neurological deficits. These findings may be useful in deciding the management of AVMs in whom total obliteration after initial GKS was not achieved.

Retrospective analysis of unstaged and staged Gamma Knife surgery with and without preceding embolization for the treatment of arteriovenous malformations

Object

The authors conducted a retrospective study to examine data on rates of obliteration of arteriovenous malformations (AVMs) with use of various combinations of treatment modalities based on Gamma Knife surgery (GKS). The authors believe that this study is the first to report on patients treated with embolization followed by staged GKS.

Methods

The authors identified 150 patients who underwent GKS for treatment of AVMs between 1994 and 2004. In a retrospective study, 4 independent groups emerged based on the various combinations of treatment: 92 patients who underwent unstaged GKS, 28 patients who underwent embolization followed by unstaged GKS, 23 patients who underwent staged GKS, and 7 patients who underwent embolization followed by staged GKS. A minimum of 3 years of follow-up after the last GKS treatment was required for inclusion in the retrospective analysis. Angiograms, MR images, or CT scans at follow-up were required for calculating rates of obliteration of AVMs.

Results

Fifty-seven of 150 patients (38%) supplied angiograms, and overall obliteration was confirmed in 43 of these 57 patients (75.4%). An additional 37 patients had follow-up MR images or CT scans. The overall obliteration rate, including patients with follow-up angiograms and patients with follow-up MR images or CT scans, was 68 of 94 (72.3%). Patients who underwent unstaged GKS had a follow-up rate of 58.7% (54 of 92) and an obliteration rate of 75.9% (41 of 54). Patients who underwent embolization followed by unstaged GKS had a follow-up rate of 53.5% (15 of 28) and an obliteration rate of 60.0% (9 of 15). Patients who underwent staged GKS had a follow-up rate of 82.6% (19 of 23) and an obliteration rate of 73.7% (14 of 19). Patients who underwent embolization followed by staged GKS had a follow-up rate of 85.7% (6 of 7) and an obliteration rate of 66.7% (4 of 6).

Conclusions

Gamma Knife surgery is an effective means of treating AVMs. Embolization prior to GKS may reduce AVM obliteration rates. Staged GKS is a promising method for obtaining high obliteration rates when treating larger AVMs in eloquent locations.