Stereotactic radiosurgery for arteriovenous malformations of the basal ganglia and thalamus: an international multicenter study

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OBJECTIVE

Arteriovenous malformations (AVMs) of the basal ganglia (BG) and thalamus are associated with elevated risks of both hemorrhage if left untreated and neurological morbidity after resection. Therefore, stereotactic radiosurgery (SRS) has become a mainstay in the management of these lesions, although its safety and efficacy remain incompletely understood. The aim of this retrospective multicenter cohort study was to evaluate the outcomes of SRS for BG and thalamic AVMs and determine predictors of successful endpoints and adverse radiation effects.

METHODS

The authors retrospectively reviewed data on patients with BG or thalamic AVMs who had undergone SRS at eight institutions participating in the International Gamma Knife Research Foundation (IGKRF) from 1987 to 2014. Favorable outcome was defined as AVM obliteration, no post-SRS hemorrhage, and no permanently symptomatic radiation-induced changes (RICs). Multivariable models were developed to identify independent predictors of outcome.

RESULTS

The study cohort comprised 363 patients with BG or thalamic AVMs. The mean AVM volume and SRS margin dose were 3.8 cm3 and 20.7 Gy, respectively. The mean follow-up duration was 86.5 months. Favorable outcome was achieved in 58.5% of patients, including obliteration in 64.8%, with rates of post-SRS hemorrhage and permanent RIC in 11.3% and 5.6% of patients, respectively. Independent predictors of favorable outcome were no prior AVM embolization (p = 0.011), a higher margin dose (p = 0.008), and fewer isocenters (p = 0.044).

CONCLUSIONS

SRS is the preferred intervention for the majority of BG and thalamic AVMs. Patients with morphologically compact AVMs that have not been previously embolized are more likely to have a favorable outcome, which may be related to the use of a higher margin dose.

ABBREVIATIONS AVM = arteriovenous malformation; BG = basal ganglia; DSA = digital subtraction angiography; EBRT = external beam radiation therapy; IGKRF = International Gamma Knife Research Foundation; mRBAS = modified radiosurgery-based AVM score; RIC = radiation-induced change; SM = Spetzler-Martin; SRS = stereotactic radiosurgery; VRAS = Virginia Radiosurgery AVM Scale.

Article Information

Correspondence Ching-Jen Chen: University of Virginia Health System, Charlottesville, VA. chenjared@gmail.com.

INCLUDE WHEN CITING Published online January 11, 2019; DOI: 10.3171/2018.8.JNS182106.

Disclosures Dr. Grills reports stock ownership and serving on the board of directors for the Greater Michigan Gamma Knife, and she reports receiving through her institution research funding from Elekta, which is unrelated to this study. Dr. Lunsford reports stock ownership in Elekta AB and serving on the data safety monitoring board for Insightec.

© AANS, except where prohibited by US copyright law.

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    Rates of favorable outcome after SRS for BG and thalamic AVMs for the following subgroups of patients: no embolization and margin dose ≥ 20 Gy (71%), no embolization and margin dose < 20 Gy (42.3%), embolization and margin dose ≥ 20 Gy (40%), and embolization and margin dose < 20 Gy (29%).

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    Kaplan-Meier plot of obliteration over time after SRS for BG and thalamic AVMs. The actuarial obliteration rates at 3, 5, and 10 years were 30.4%, 43.3%, and 63.2%, respectively.

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