Gamma knife radiosurgery for arteriovenous malformations: the Furukawa experience

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.

Long-term outcomes of 170 brain arteriovenous malformations treated by frameless image-guided robotic stereotactic radiosurgery: Ramathibodi hospital experience

This study was conducted to report long-term outcomes of the frameless robotic stereotactic radiosurgery (SRS) for brain arteriovenous malformation (AVM) at Ramathibodi Hospital.Retrospective data of patients with brain AVM (bAVM), who underwent CyberKnife SRS (CKSRS) at Ramathibodi Hospital from 2009 to 2014, were examined. Exclusion criteria were insufficient follow-up time (<36 months) or incomplete information. Patients' demographics, clinical presentation, treatment parameters, and results were analyzed. Excellent outcome was defined as AVM obliteration without a new neurological deficit. Risk factors for achieving excellent outcome were assessed.From a total of 277 CKSRS treatments for bAVM during the 6 years, 170 AVMs in 166 patients met the inclusion criteria. One hundred and thirty-nine cases (81.76%) presented with hemorrhages from ruptured bAVMs. Almost two-thirds underwent embolization before radiosurgery. With the median AVM volume of 4.17 mL, three-quarters of the cohort had single-fraction CKSRS, utilizing the median prescribed dose of 15 Gray (Gy). In the multisession group (25.29%), the median prescribed dose and the AVM volume were 27.5 Gy and 22.3 mL, respectively. An overall excellent outcome, at a median follow-up period of 72.45 months, was observed in 99 cases (58.24%). Seven AVMs (4.12%) ruptured after CKSRS but 1 patient suffered a new neurological deficit. Two patients (1.18%) were classified into the poor outcome category but there were no deaths. Negative factors for excellent outcome, by multivariate regression analysis, were the male sex and multisession SRS delivery, but not age, history of AVM rupture, previous embolization, or AVM volume.Despite relatively larger bAVM and utilizing a lower prescribed radiation dose, the excellent outcome was within the reported range from previous literature. This study offers one of the longest follow-ups and the largest cohorts from the frameless image-guided robotic SRS community.

Modern robot-assisted radiosurgery of cerebral angiomas-own experiences, system comparisons, and comprehensive literature overview

Cerebral arteriovenous malformations (AVMs) are rare vascular lesions potentially responsible for substantial neurological morbidity and mortality. Over the past four decades, radiosurgery has become a valid therapeutic option for many patients with small intracranial AVMs, but reports describing the use of robotic stereotactic radiosurgery (SRS) are rare. The purposes of this study are to describe the efficacy and toxicity of robotic SRS for AVMs and to review the literature. The reports of 48 consecutive patients treated with SRS were reviewed. A total dose of 18 Gy in a single fraction was prescribed to the 70% isodose line. Efficacy (i.e., total obliteration of the AVM) and toxicity were analyzed. Literature search was performed on Embase and PubMed for the terms "Radiosurgery and AVMs", "Cyberknife and AVMs" and "Radiation therapy and AVMs." The median follow-up was 41 months. The median AVM volume was 2.62 cm³. The incidence of obliteration was 59% at 3 years. Regarding toxicity, 92% of patients remained symptom-free, 66% developed radiogenic edema on MRI, and none developed radionecrosis. Forty-one patients (85%) had embolization prior to SRS. Our study was incorporated in an exhaustive review of 25 trials categorized by SRS technique. In this review, the median follow-up was 60 months. The median nidus volume was 2 cm³. The median overall obliteration rate for SRS was 68% (range 36 to 92). The median embolization rate prior to SRS was 31% (range 8.23 to 90). Compared to other studies, tolerability was excellent and the obliteration rate was acceptable but probably affected by the high embolization rate prior to radiosurgery. Our study suggests that a higher dose is feasible. A larger cohort with a longer follow-up period will be needed to confirm the safety and effectiveness, and subsequently validate different prognosis and predictive scores with this treatment modality to maximize the benefits of this technology for selected patients in the long term.

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.

Long-term Outcomes After Staged-Volume Stereotactic Radiosurgery for Large Arteriovenous Malformations

BACKGROUND:

Stereotactic radiosurgery is an effective treatment modality for small arteriovenous malformations (AVMs) of the brain. For larger AVMs, the treatment dose is often lowered to reduce potential complications, but this decreases the likelihood of cure. One strategy is to divide large AVMs into smaller anatomic volumes and treat each volume separately.

OBJECTIVE:

To prospectively assess the long-term efficacy and complications associated with staged-volume radiosurgical treatment of large, symptomatic AVMs.

METHODS:

Eighteen patients with AVMs larger than 15 mL underwent prospective staged-volume radiosurgery over a 13-year period. The median AVM volume was 22.9 mL (range, 15.7-50 mL). Separate anatomic volumes were irradiated at 3- to 9-month intervals (median volume, 10.9 mL; range, 5.3-13.4 mL; median marginal dose, 15 Gy; range, 15-17 Gy). The AVM was divided into 2 volumes in 10 patients, 3 volumes in 5 patients, and 4 volumes in 3 patients. Seven patients underwent retreatment for residual disease.

RESULTS:

Actuarial rates of complete angiographic occlusion were 29% and 89% at 5 and 10 years. Five patients (27.8%) had a hemorrhage after radiosurgery. Kaplan-Meier analysis of cumulative hemorrhage rates after treatment were 12%, 18%, 31%, and 31% at 2, 3, 5, and 10 years, respectively. One patient died after a hemorrhage (5.6%).

CONCLUSION:

Staged-volume radiosurgery for AVMs larger than 15 mL is a viable treatment strategy. The long-term occlusion rate is high, whereas the radiation-related complication rate is low. Hemorrhage during the lag period remains the greatest source of morbidity and mortality.