Borden DAVF Classification System

Borden et al categorized DAVFs based on the relationship between the venous drainage pattern and the clinical presentation (21).

• Borden type I DAVFs drain directly into the dural venous sinus or meningeal vein: Flow is in a normal direction and their course is typically benign.
• Borden type II DAVFs drain into the venous sinuses, with retrograde drainage into the leptomeningeal veins: They usually present with symptoms related to venous hypertension or hemorrhage.
• Borden type III DAVFs drain into the leptomeningeal veins: In these DAVFs, the sinus may be patent or occluded; however, when the sinus is patent, the arterialized vein and the sinus are not in communication at the point of the fistula. They also present with hemorrhage or other manifestations of venous hypertension.
• Subclassification: The above three types of malformations can be subclassified into subtype a, simple fistula, or subtype b, multiple fistulas.