A young adult presents with proptosis and pain in eye after 4 days of trauma to eye. Chemosis, conjunctival congestion and extraocular muscle palsy with inability to move eye are seen.Investigation of choice -

Information in this question are :- Presentation 4 days after trauma Traumatic proptosis along with chemosis and conjunctival congestion Extraocular muscle palsy (ophthalmoplegia) Given the patient's clinical presentation of proptosis with chemosis and conjunctival congestion in the setting of cranio-facial injury, a traumatic carotid-cavernous fistula is suspected. Most likely diagnosis is carotico-cavernous fistula. Selective carotid angiography using digital subtraction techniques is the investigation of choice. Another condition which may present with similar features is CST, but it is very rare after trauma.