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

Abstract

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.

Pediatric Intracranial Arteriovenous Malformation: Long-Term Outcomes with Linear Accelerator (LINAC)-Based Radiosurgery

“…Recent comparative analysis has shown the continuous scoring modified radiosurgery-based AVM score (mRBAS) as outperforming other grading systems, and thus it was used for this analysis. 15 , 16 , 17 , 18 , 19 , 20 The score is calculated as follows: …”

Histopathology of brain AVMs part II: inflammation in arteriovenous malformation of the brain

“…In addition, when left incomplete due to technical or anatomical challenges, incomplete embolization may in fact increase rupture risk [34]. In recent years, stereotactic radiosurgery (SRS), which targets a high dose of radiation at the malformation with the aim of inducing radiation-related necrosis and obliteration of the bAVM, has become a powerful treatment tool, especially for smaller bAVMs [25]. The use of effective doses in SRS is, however, limited by lesion size and the effect of SRS comes with a significant delay of several years during which time the patient is exposed to risk of rupture.…”

Brain Arteriovenous Malformations: Impact of Neurologic Status, Bleeding, and Type of Treatment on Final Outcome

“…The mean Pollock-Flickinger score for the radiosurgical group was 1.5, similar to what has been reported in other studies. 4,10,15 For treatment selection, the final choice was made depending on the AVM characteristics and the clinical situation of the patient. The obliteration rates for the microsurgical group was 96%, similar to that in the meta-analysis of van Beijnum et al 11 In the radiosurgical group, the obliteration rate was 52.77%; this rate was higher than that in a previous meta-analysis but lower than in the studies of Starke et al 10 (64.7%) or Pollock et al 4 (75%) as a result of longer follow-up of these patients.…”

“…However, reducing exclusion criteria also increases generalizability (external validity) of the study. 4,6,16,18,19 Furthermore, in prior publications, the patients' baseline situation is not always provided, with few information on changes in functional status; often, only the final outcome is provided. However, we believe that longitudinal information is essential to recognize the impact of the treatment modality on the neurologic outcome and the general evolution of the patients.…”