The commonly used Borden and Cognard classification systems for the prediction 
of clinical behavior of cranial dural arteriovenous shunts focus on the venous 
drainage, particularly the presence of leptomeningeal venous drainage, and on 
the direction of flow, particularly the presence of retrograde flow. In 
addition, the latter includes ectasia and spinal drainage as criteria of two 
distinct grades. However, none of the above classifications (a) differentiates 
direct from exclusive leptomeningeal venous drainage, (b) considers cortical 
venous congestion as a factor potentially associated with an aggressive clinical 
course, and (c) anticipates ectasia in shunts with a mixed dural-cortical venous 
drainage (type 2). In this study, we analyzed the angiographic images of 107 
consecutive patients having a cranial dural arteriovenous fistula with 
leptomeningeal venous drainage, based on a newly developed scheme. This scheme, 
symbolized with the acronym "DES," groups the dural shunts according to three 
factors: directness and exclusivity of leptomeningeal venous drainage and signs 
of venous strain. According to the combination of the three factors, eight 
different groups were distinguished. All analyzed cases could be assigned to one 
of these groups. Directness of leptomeningeal venous drainage expresses the 
exact site of the shunt (bridging vein vs sinus wall), whereas exclusivity 
expresses venous outlet restrictions. All bridging vein shunts had a direct 
leptomeningeal venous drainage. Almost all bridging vein shunts and all 
"isolated" sinus shunts had an exclusive leptomeningeal venous drainage. Venous 
strain, manifested as ectasia and/or congestion, denotes the decompensation of 
the cerebral venous system due to the shunt reflux. The comparison of the 
presented concept with the currently used classifications highlighted the 
advantages of the former and the weaknesses of the latter.