What is the risk of yearly hemorrhage, morbidity, and mortality with a high-grade ethmoidal dural arteriovenous fistula (dAVF) with venous varices?

Risk of Hemorrhage, Morbidity, and Mortality with High-Grade Ethmoidal dAVF with Venous Varices

High-grade ethmoidal dural arteriovenous fistulas (dAVFs) with venous varices carry an annual hemorrhage risk of approximately 10%, with rates increasing to 21% when venous ectasia is present, and a mortality rate of 10-30% from the first hemorrhage. 1, 2

Hemorrhage Risk Factors and Annual Rates

• High-grade dAVFs (Borden Type III) with cortical venous drainage have a significantly elevated risk of hemorrhage compared to lower-grade fistulas 1
• The annual hemorrhage risk for high-grade dAVFs (Borden Type III) is approximately 10% (95% CI: 4%-20%) 1
• When venous ectasia (varices) is present, this risk increases substantially to 21% per year (95% CI: 4%-66%) 1
• Ethmoidal location is particularly concerning, with hemorrhage rates reported as high as 91% in anterior cranial fossa dAVFs 3
• Previous hemorrhage significantly increases the risk of recurrent hemorrhage, with rates of 32.9% in the first year after initial hemorrhage 2

Mortality and Morbidity

• Mortality from the first hemorrhage from dAVFs ranges between 10% and 30% 2
• Among survivors of hemorrhage, 10% to 20% experience long-term disability 2
• The combined permanent morbidity and mortality rate following surgical treatment is approximately 17%, which is considered acceptable given the natural history of the disease 4
• For symptomatic high-grade dAVFs, only about 42% of patients are independent (modified Rankin Scale 0-2) before intervention 4

Risk Stratification by Presentation

• Asymptomatic or minimally symptomatic high-grade dAVFs have a lower annual hemorrhage rate of approximately 2% (95% CI: 0.2%-8%) 1
• Those presenting with non-hemorrhagic neurological deficits have an increased annual hemorrhage rate of 10% (95% CI: 0.9%-41%) 1
• Patients with previous hemorrhage have the highest annual rebleeding rate at 46% (95% CI: 11%-130%) 1

Treatment Considerations

• Given the high risk of hemorrhage, mortality, and morbidity, high-grade ethmoidal dAVFs with venous varices require prompt treatment 4
• Stereotactic radiosurgery is not recommended for high-grade dAVFs with direct cortical venous drainage due to the high risk of hemorrhage during the latency period 4, 2
• Surgical treatment of high-grade dAVFs is associated with a high angiographic cure rate (96%) with acceptable morbidity and mortality 4
• Endovascular approaches can be limited by access difficulties, incomplete obliteration, and recanalization, but newer techniques show promising results 4, 3
• Transvenous embolization techniques have demonstrated high complete occlusion rates with procedural morbidity rates of 2-4.5% in recent series 2

Clinical Pitfalls and Caveats

• High-grade dAVFs can sometimes be misdiagnosed as cerebral venous sinus thrombosis due to similar clinical and imaging manifestations 5
• Anticoagulation therapy is contraindicated in high-grade dAVFs with retrograde venous flow due to increased hemorrhage risk 5
• Early and subacute hemorrhagic complications after partial treatment can occur due to altered hemodynamics or inadvertent occlusion of draining veins 2
• Careful blood pressure monitoring and control in the postoperative period are critical to prevent hemorrhagic complications 2
• The risk of recurrent hemorrhage is highest in the first year after initial hemorrhage, necessitating prompt intervention 2