Prognostic variables and outcome in relation to different bleeding patterns in arteriovenous malformations.

Subarachnoid hemorrhage as bleeding pattern occurs rarely in ruptured arteriovenous malformations (AVM). The aim of the present study is to evaluate different bleeding patterns in hemorrhages due to an AVM and their impact on outcome in terms of risk and treatment stratification. We evaluated 158 patients with ruptured AVMs who were admitted to our neurosurgical department from 2002 to 2017. We compared different bleeding patterns, such as intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), or both (ICH + SAH) and evaluated predictive variables for outcome in the last follow-up. ICH was found in 48.7% of patients, isolated SAH in 20.9% of patients, and both in 30.4% of patients. The mean parenchymal blood volume was 34.5cm3. 38.6% of the patients had AVM-associated aneurysms, mostly located pre-nidal (77%). AVMs with ruptured aneurysms often resulted in ICH with SAH component (p < 0.001) and SAH pattern occurred more often infratentorial (p = 0.003). In a multivariate logistic regression model, poor clinical state on admission (WFNS IV-V) (p < 0.01), eloquence, infratentorial location (p = 0.05), and presence of ICH with SAH component (p = 0.02) were the most relevant predictors of a poor outcome after AVM rupture. Bleeding pattern in AVM hemorrhage depends on angioarchitectural and hemodynamic features and SAH component predicts outcome negatively. AVM-associated pre-nidal aneurysms may harbor a higher risk for rupture and SAH pattern when located infratentorial. Treatment decisions and risk stratifications should be considered in view of these findings.