The Significance of Venous Outflow Obstruction in Dural Arteriovenous Fistulas

The association between venous outflow obstruction (VOO) and cranial dural arteriovenous fistulas (DAVF) is well established; however, its impact on the natural history remains unclear. This article aims to characterize its clinical significance and further describe the natural history of DAVF.

A retrospective cohort study was performed at a tertiary neurosurgical center. Cohort characteristics were described with a focus on patients with VOO. Annualized event rates and risk factors for hemorrhage and nonhemorrhagic neurological events (NHNE) were also investigated.

The cohort consisted of 108 patients, 74 of which had follow-up greater than 1 month including 24 low-grade (Cognard I-IIa) fistulas (21.7 lesion-years) and 50 high-grade (Cognard IIb-V) fistulas (60 lesion-years). 18 patients with concurrent VOO were identified; most (83.3%) were high-grade DAVF and had obstruction of the direct draining sinus. Annualized rates of hemorrhage and NHNE for high-grade DAVF were 4.6% and 10.6%, respectively. Those high-grade lesions presenting with hemorrhage had a 10.9% annual rate of recurrent hemorrhage, while those presenting with NHNE had a 22.3% annual rate of subsequent NHNE. Fifteen high-grade DAVF with VOO (15.7 lesion-years) had annualized hemorrhage and NHNE rates of 6.4% and 31.9%, respectively. High radiological grade, an aggressive index presentation, and the presence of VOO were the predictors of hemorrhage and NHNE (P < .05).

This study reports a novel association between VOO and a more aggressive clinical course. DAVF with high-grade angiographic features, an aggressive index presentation, or VOO should be considered for early treatment.