A Case of Right-Sided Direct Carotid Cavernous Fistula: A Diagnostic Challenge

BACKGROUND Carotid cavernous fistulas (CCFs) are rare potentially sight-threatening abnormal connections between carotid artery and cavernous sinus. CASE REPORT We report a case of CCF in an 83-year-old female, who presented with swollen and painful right eye. The patient was initially treated with empiric antibiotics for suspected peri-orbital cellulitis, as noted clinically and in computed tomography (CT) orbits. However, lack of clinical improvement, physical finding of orbital bruit/thrill, and enlarged superior ophthalmic vein in magnetic resonance (MR) orbits suggest alternate diagnoses. Eventually, CT angiogram (CTA) and carotid-arteriography confirmed the diagnosis of right-sided direct CCF, which was subsequently treated with endovascular embolization. Not only does this case highlight the importance of CCF, which could be a differential diagnosis of swollen red eye, it also addresses the vital importance of physical examination in modern medicine despite the seemingly promising technologies. CONCLUSIONS Internists should have a low threshold of clinical suspicion for CCF in a patient with swollen red eyes in order to provide timely and proper management.