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

INTRODUCTION: Carotid Cavernous Fistulas (CCFs) are a rare type of arteriovenous shunt that develop within the cavernous sinus (CS). Direct CCFs entails a direct communication between the cavernous internal carotid artery (cICA) and the CS and are typically high flow lesion. Most CCFs drains 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 intra-cerebral hemorrhage. We present a rare case of post-traumatic, direct, low-flow CCF associated with cerebral haemorrhage, a typical venous drainage pattern and without ocular symptoms at presentation.

CASE: A 76 years old woman hospitalized for a post-traumatic fronto-temporopolar haemorrhage associated with multiple fractures of the maxillo-facial and cranial base skeleton and midline shift > 10mm. On neurologic examination the GCS was 8 and right anisocoria was present. Immediate surgical evacuation of the hematoma was performed. A severe arterial bleeding from the anterior third of the middle cranial fossa floor was controlled intraoperatively. Postoperative brain angioMRI and DSA showed a direct CCF without theft phenomenon. Ocular symptoms, and ultimately loss of function of the right eye, appeared two weeks from surgery. Endovascular treatment of the CCF was attempted attaining partial closure of the shunt using coils.

DISCUSSION: Direct low-flow CCFs are exceedingly rare lesions. Five cases have been described in the literature, four were associated with spontaneous rupture of a cavernous carotid aneurysm while only one case was associated with post traumatic rupture of a cICA pseudo aneurysm. In addition, despite our patient 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.