A 30-year-old man presents with pulsatile proptosis, chemosis, bruit over the orbit, and dilated tortuous episcleral vessels. He had a road traffic accident 3 weeks ago. The MOST likely diagnosis and the investigation of choice is:

• A Cavernous hemangioma of the orbit; orbital MRI with gadolinium
• B Orbital varix; Valsalva MRI demonstrating intermittent proptosis
• C Carotid-cavernous fistula (CCF); digital subtraction angiography (DSA) ✓
• D Thyroid eye disease with orbital congestion; thyroid function tests and orbital Doppler

Explanation

Post-traumatic pulsatile proptosis with orbital bruit, chemosis, and dilated arterialized episcleral vessels is pathognomonic of a direct (high-flow) carotid-cavernous fistula (CCF type A — direct communication between internal carotid artery and cavernous sinus). Trauma causes tear of the ICA in the cavernous sinus. The gold standard investigation is digital subtraction angiography (DSA/cerebral angiography), which also allows simultaneous endovascular treatment (detachable balloon or coil embolization of the fistula). Indirect CCF (dural fistulas) have similar but milder presentation.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.