Table 1.

The Barrow classification of CCFs

	Responsible blood vessel	Frequency	Etiology	Mainly Population	Haemodynamics	Progress
Type A	shunt between the ICA and cavernous sinus	More than 70%	associated with trauma	young male	high-flow CCFs	acute
Type B	shunt between the meningeal branches of the ICA and cavernous sinus	Less than 30%	Spontaneous	older female	low-flow CCFS	chronic or relapsing
Type C	shunt between the meningeal branches of the external carotid artery and cavernous sinus
Type D	shunt between the meningeal branches of the ICA, external carotid artery, and cavernous sinus