Sinovenous outflow restriction predisposes lateral sinus dural arteriovenous fistulas to obliteration after endovascular therapy

OBJECTIVES: To examine the impact of angiographic markers on endovascular therapy (EVT) outcomes in patients with lateral sinus dural arteriovenous fistulas (LSDAVFs). METHODS: We analyzed the data of 81 patients who completed their first EVT session for LSDAVFs between December 2011 and February 2025 at our institute. Angiograms obtained before EVT were evaluated for LSDAVF characteristics. Shunt patterns were categorized as direct sinus fistula type, compartmental sinus channel type, mural channel type, and bridging vein shunt type. Sinovenous outflow patency was evaluated using the combined conduit score (CCS), a 9-point scoring system with scores ranging from 0 (total occlusion) to 8 (full patency). Multivariate logistic regression and Cox regression were used to identify key parameters associated with complete LSDAVF obliteration after EVT. RESULTS: Of the 81 patients, 46 (56.8%) achieved immediate obliteration after EVT. Multivariate logistic regression revealed that a CCS <4, jugular bulb involvement, and ipsilateral meningohypophyseal trunk supply were independent parameters associated with immediate obliteration. After a median imaging follow-up duration of 11.4 months, 36 out of 60 patients (60%) achieved complete obliteration without further treatment. Multivariate Cox regression revealed that a CCS <4 was independently associated with complete obliteration (HR 3.061, P=0.006). CONCLUSION: LSDAVFs with sinovenous outflow restriction, indicated by a CCS <4, were more likely to be obliterated after EVT compared with those without outflow restriction. In patients with LSDAVFs, the CCS may assist in outcome prediction and therapeutic decision-making.