Cerebral venous system stenosis in the sigmoid sinus with resultant dilatation and tortuosity of the cavernous sinus mimicking carotid cavernous fistula

Background: Cerebral venous system stenosis (CVSS) is a form of cerebral venous vascular disease that was known to be a rare occurrence with notable scarcity of clinical evidence and cases reported in the literature. This condition might impair venous outflow and result in dilatation of the remaining cerebral venous circulation. However, CVSS resulting in dilatation and tortuosity of the cavernous sinus and ophthalmic vein, which resulted in a clinical appearance that mimicked carotid cavernous fistula (CCF), was never reported previously. CCF is an abnormal arteriovenous communication within the cavernous sinus that is also a well-known cause for cavernous sinus and ophthalmic vein dilatation. Case Description: A 6-year-old boy presented with gradual protrusion of the left eye for 7 months without any recognizable history of trauma. Computed tomography (CT) angiography showed dilatation and tortuosity of the left cavernous sinus and left ophthalmic vein without any signs of direct communication between the internal carotid artery and cavernous sinus; such findings were suggestive of indirect CCF. Cerebral angiography was performed and revealed that there were no signs of indirect arterial branches communicating to the cavernous sinus; instead, the result confirmed nonvisualization of the right sigmoid sinus and prominent left transverse sinus with abrupt transition in the sigmoid sinus suggesting hypoplasia/atresia of the right sigmoid sinus and stenosis of the left sigmoid sinus with resultant dilatation in transverse sinus and cavernous sinus. Conclusion: This case highlighted the possibility of CVSS as a differential diagnosis of CCF, especially in atypical cases, along with the role of CT angiography and conventional cerebral angiography in determining vascularization of such cases.