Carotid-cavernous fistula
C. Refer the patient for urgent neuroimaging
Clinically, the most likely diagnosis is carotid-cavernous fistula (CCF)—an abnormal communication between the carotid artery (or its branches) and the cavernous sinus, causing high-pressure arterial blood flow within the low-pressure veins, sinuses, and cavernous sinus.1,2 Arterialized (“corkscrew”) conjunctival blood vessels are shown in Figure 1. Other features of this case consistent with CCF included raised IOP (due to increased episcleral venous pressure), conjunctival chemosis, and visual blurring. Significant visual loss may occur secondary to traumatic, ischemic, or glaucomatous optic neuropathy.
In 75% of CCF cases there is a direct connection between the intracavernous segment of the internal carotid artery (ICA) and the cavernous sinus, usually due to arterial wall trauma after head injury.3 Acute high-flow symptoms of direct CCFs (commonly used terms) include visual blurring, motility disorders, proptosis, chemosis, and orbital bruits.