Angio-Architectural Features of High-Grade Intracranial Dural Arteriovenous Fistulas: Correlation with Aggressive Clinical Presentation and Hemorrhagic Risk

BACKGROUND: High-grade dural arteriovenous fistulas (dAVFs) can present shunts with very different angio-architectural characteristics. Specific hemodynamic factors may affect clinical history and determine very different clinical courses. OBJECTIVES: To evaluate the relationship between some venous angio-architectural features in high-grade dAVFs and clinical presentation. Specific indicators of moderate or severe venous hypertension were analyzed, such as altered configurations of the dural sinuses (by a single or a dual thrombosis), or overload of cortical vessels (restrictions of outflow, pseudophlebitic cortical vessels, and venous aneurysms). METHODS: The institutional series was retrospectively reviewed (49 cases), and the pattern of venous drainage was analyzed in relationship with clinical presentation (benign/aggressive/hemorrhage). RESULTS: Thirty-five of 49 cases displayed cortical reflux (high-grade dAVFs). This subgroup displayed a benign presentation in 31.42% of cases, an aggressive in 31.42%, and hemorrhage in 37.14%. CONCLUSIONS: Our data confirm that within high-grade dAVFs, 2 distinct subpopulations exist according to severity of clinical presentation. Some indicators we examined showed correlation with aggressive nonhemorrhagic manifestations (outflow restriction and pseudophlebitic cortical vessels), while other showed a correlation with hemorrhage (dual thrombosis and venous aneurysms). Current classifications appear insufficient to identify a wide range of conditions that ultimately determine the organization of the cortical venous drainage. Intermediate degrees of venous congestion correlate better with the clinical risk than the simple definition of cortical reflux. The angiographic aspects of venous drainage presented in this study may prove useful to assess dAVF hemodynamic characteristics and identify conditions at higher clinical risk.