Introduction: Longitudinal studies describing the incidence of hemorrhage in untreated arteriovenous malformations (AVMs) demonstrate factors associated with increased hemorrhage risk, including both angiographic and clinical characteristics. However, these studies include an inherent bias by the selection of AVMs deemed most appropriate for conservative management. Alternatively, studies focusing on hemorrhagic presentation of AVMs aim to avoid this bias, but have largely limited their analysis to descriptions of angiographic features. We report the importance of race/ethnicity as a new clinical predictor of AVM hemorrhagic presentation in addition to previously reported angiographic features.
Methods: We prospectively and retrospectively collected patients(n=194) from 1993-2010, who had a single intracranial AVM and compared baseline characteristics for hemorrhagic presentation vs. non-hemorrhagic presentation using t-test/Wilcoxon rank sum test or chi-square. Univariate analysis was performed on 19 clinical and angiographic variables. Features that were statistically or clinically significant were included in a multivariate analysis.
Results: The median age was 32 years(0-74), with 37.2% male. Spetzler-Martin grades were: I(17.5%), II(37.1%), III(28.9%), IV(14.9%), and V(1.5%). Significant baseline characteristics between hemorrhage vs. non-hemorrhagic presentation groups were: race(p=.0009), AVM size(p<.0001), <3 feeding arteries(p=0.0139), absence of MCA feeding artery(p=.0045) and AVM location(p=.0067). Univariate analysis revealed age, race, AVM size, MCA feeding artery, feeding artery number, Spetzler-Martin grade and AVM location as statistically significant. Multivariate analysis revealed non-white race(OR=3.09[1.52-6.44],p=.0021), smaller AVM size(OR=0.65[0.19-0.86],p=.0036) and non-frontal lobar (OR=2.61[1.2-5.59],p=.0171), basal ganglia(OR=6.20[1.52-26.26],p=.0114) or brainstem locations(OR=4.41[1.38-14.92],p=.0139) as risk factors for hemorrhagic presentation.
Conclusions: Studies of AVM natural history have demonstrated angiographic features and race/ethnicity as increasing hemorrhagic risk, but impose a selection bias for untreated AVMs. In this study, we confirmed previous observations that AVM size and location are associated with hemorrhagic presentation. To our knowledge, this is the first study that demonstrates the clinical variable of race/ethnicity as a risk factor for hemorrhagic presentation.
Patient Care: Our study identifies important features associated with the hemorrhagic presentation of AVMs. Whereas previous studies examining hemorrhagic presentation have focused on angiographic features, this study identifies race/ethnicity as an important risk factor associated with hemorrhagic presentation. Previous longitudinal studies have identified race/ethnicity as an important predictor of increased hemorrhagic risk. However, these studies impose a bias through the selection of patients deemed appropriate for conservative management. Our study will further help neurosurgeons when confronted with the risk stratification of patients with AVMs.
Learning Objectives: 1) Understand the limitations of longitudinal studies of AVMs
2) Understand the role race/ethnicity plays in hemorrhagic presentation of AVMs
3) Understand the role angiographic features play in hemorrhagic presentation of AVMs