Abnormal flow in the cavernous sinus caused by an asymptomatic dural arteriovenous fistula of the contralateral transverse-sigmoid sinus.

A 53-year-old asymptomatic man underwent cranial MR imaging to rule out cerebrovascular disease. On T2-weighted axial images abnormal flow voids were detected at the right cavernous sinus, suggesting a dural carotid-cavernous fistula (CCF). On the MR angiogram, abnormal high intensity signals were observed at the right cavernous sinus and the left transverse-sigmoid (T-S) sinus, suggestive of coexisting right dural CCF and dural arteriovenous fistula (AVF) of the left T-S sinus. Selective cerebral angiography of the left external carotid artery revealed abnormal flow in the right cavernous sinus caused by the dural AVF of the left T-S sinus via the right inferior petrosal sinus due to occlusion of both the distal left sigmoid sinus and proximal right internal jugular vein.