This article presents a modification to the existing classification scales of 
intracranial dural arteriovenous fistulas based on newly published research 
regarding the relationship of clinical symptoms and outcome. The 2 commonly used 
scales, the Borden-Shucart and Cognard scales, rely entirely on angiographic 
features for categorization. The most critical anatomical feature is the 
identification of cortical venous drainage (CVD; Borden-Shucart Types II and III 
and Cognard Types IIb, IIa + b, III, IV, and V), as this feature identifies 
lesions at high risk for future hemorrhage or ischemic neurological injury. Yet 
recent data has emerged indicating that within these high-risk groups, most of 
the risk for future injury is in the subgroup presenting with intracerebral 
hemorrhage or nonhemorrhagic neurological deficits. The authors have defined 
this subgroup as symptomatic CVD. Patients who present incidentally or with 
symptoms of pulsatile tinnitus or ophthalmological phenomena have a less 
aggressive clinical course. The authors have defined this subgroup as 
asymptomatic CVD. Based on recent data the annual rate of intracerebral 
hemorrhage is 7.4-7.6% for patients with symptomatic CVD compared with 1.4-1.5% 
for those with asymptomatic CVD. The addition of asymptomatic CVD or symptomatic 
CVD as modifiers to the Borden-Shucart and Cognard systems improves their 
accuracy for risk stratification of patients with high-grade dural arteriovenous 
fistulas.