Atypical manifestation of direct low-flow carotid-cavernous fistula. Case report and review of the literature

Background: Carotid cavernous fistula (CCF) is a rare type of arteriovenous shunt that develops within the cavernous sinus (CS). Direct CCFs entail a direct communication between the cavernous internal carotid artery and the CS and are typically high-flow lesions. Most CCFs drain into the ophthalmic veins (typical venous drainage pattern), leading to the pathognomic ocular clinical triad associated with a CCF. When an obstruction of the typical venous outflow is present, the arterial pressure generated by the fistula is transmitted into the cerebral venous system via the sphenoparietal sinus, which might lead to intracerebral hemorrhage. We present a rare case of posttraumatic, direct, low-flow CCF associated with cerebral hemorrhage, a typical venous drainage pattern, and without ocular symptoms at presentation. Case Description: A 76-year-old woman was hospitalized for a posttraumatic frontotemporopolar hemorrhage associated with multiple fractures of the maxillofacial and cranial base skeleton and midline shift >10 mm. On neurologic examination the Glasgow Coma Scale was 8 and right anisocoria was present. Immediate surgical evacuation of the hematoma was performed. Severe arterial bleeding from the anterior third of the middle cranial fossa floor was controlled intraoperatively. Postoperative brain angio−magnetic resonance imaging and digital subtraction angiography showed a direct CCF without theft phenomenon. Ocular symptoms, and ultimately loss of function of the right eye, appeared 2 weeks from surgery. Endovascular treatment of the CCF was attempted attaining partial closure of the shunt using coils. Conclusions: Direct low-flow CCFs are exceedingly rare lesions. Five cases have been described in the literature, 4 of which were associated with spontaneous rupture of a cavernous carotid aneurysm while only 1 case was associated with posttraumatic rupture of a cavernous internal carotid artery pseudoaneurysm. In addition, despite our patient having developed an intraparenchymal hemorrhage most probably correlated to the CCF, the latter was associated with a typical venous drainage via the superior ophthalmic vein, which is uncommonly correlated to intraparenchymal bleeding.