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

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Abstract

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.

Introduction

Brain arteriovenous malformations (AVMs) occur at an incidence of 1.12-1.42 per 100,000 person-years.1 Steiner et al.2 reported the first successful obliteration of an AVM using radiosurgery in 1972. Radiosurgery technology has evolved significantly, and minimally invasive stereotactic radiosurgery (SRS) has become a standard of care in managing brain AVMs, especially those located in deep or eloquent regions that would present high surgical risks.3,4 High AVM obliteration rates have been reported with SRS,5, 6, 7 and multiple factors have been found to be associated with obliteration following SRS for brain AVMs. However, the reporting of these factors in the literature has been inconsistent and disorganized. This study analyzes our experience with linear accelerator (LINAC)–based SRS for brain AVMs, including treatment success, radiation side-effects, and factors associated with obliteration, and reviews the various reported predictors of AVM obliteration and compares to our patient population.

Section snippets

Patient Selection

The study protocol was approved by the Institutional Review Board. This retrospective study reviewed electronic medical records using our institution's EMERSE database8 to identify patients diagnosed with brain AVMs treated with SRS. International Classification of Diseases codes for brain AVMs in association with the Current Procedural Terminology code for SRS were used to identify the target population.8

We included all patients with brain AVMs confirmed with vascular imaging and treated with

Baseline Characteristics

One hundred forty-two AVMs in 128 patients treated with SRS were included. Mean patient age was 34.4 years (range 3-75). Forty-one treated AVMs (28.9%) were in patients ≤18 years old, and 73 AVMs (51.4%) were in males. Forty-three AVMs (30.3%) were treated before 2005. Seventy-four AVMs (52.1%) were associated with a hemorrhage before SRS, and 21 (14.8%) had been previously embolized without complete obliteration prior to SRS. The mean clinical follow-up time was 67.8 months (range 24-256), and

AVM Obliteration

AVM obliteration via LINAC-based radiosurgery was achieved in 80.3% in our series. Reported obliteration rates have varied widely (60-94%),5, 6, 7,9, 10, 11, 12, 13 partly because of differences between studies in the selected patient population, AVM characteristics and the method of determining AVM obliteration. Comparable to most series, Spetzler-Martin grades 3 and 2 were most frequently treated with SRS, with the majority of AVMs deemed to be in an eloquent location. Two early prominent

Conclusions

AVM obliteration with LINAC-based radiosurgery is safe and and is complete in approximately 80% of cases. Several factors associated with AVM obliteration have been identified but inconsistently reported due to inherent differences in study populations, as reviewed in the current study. The most prominent predictors of obliteration success include AVM size and volume, radiation dose, number of draining veins and patient age. Other factors to consider in assessing the efficacy of SRS include the

Declaration of Competing Interest

The authors report no conflict of interest.

Grant Support

None

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