Angioarchitectural Analysis of Arteriovenous Shunts in Dural Arteriovenous Fistulas and Its Clinical Implications

BACKGROUND: Detailed understanding of the angioarchitecture of arteriovenous shunts in dural arteriovenous fistulas (DAVFs) is essential when planning endovascular treatment. OBJECTIVE: To analyze shunt patterns and their clinical implications in transverse-sigmoid sinus and superior sagittal sinus DAVFs. METHODS: A total of 48 DAVFs treated with endovascular embolization between January 2010 and June 2021 were investigated. The preprocedural and intraprocedural digital subtraction angiograms were examined to characterize the shunt patterns of DAVFs in terms of anatomic relations to the sinuses and cortical veins. Treatment characteristics and outcomes were evaluated. RESULTS: The shunt patterns were categorized into 4 types: the direct sinus fistula (n = 8/48, 16.7%), compartmental sinus channel (n = 14/48, 29.1%), mural channel (n = 13/48, 27.1%), and bridging vein shunt (n = 13/48, 27.1%). Mural channel lesions revealed direct (n = 4/13, 30.8%) and indirect (n = 6/13, 46.2%) cortical venous connections. Multiple shunt types were seen in 7 patients. Overall, complete or near-complete occlusion was achieved in 43 patients (89.6%) after the final embolization. Patients with mural channels received the most embolization sessions (1.4 sessions per patient). Procedural venous drainage-related complications occurred in patients with multiple shunt types including mural channel shunts (n = 3). All bridging vein shunts were completely occluded during a single transarterial embolization session. CONCLUSION: The 4 shunt patterns of DAVFs demonstrate distinct characteristics for the fistula, sinus and cortical vein connection. Meticulous analysis of the angioarchitectural characteristics and clinical implications is warranted for safe and effective treatment.