High index of suspicion: diagnosing a carotid-cavernous fistula

A woman in her 70s presented with acute bilateral retro-orbital headache, diplopia, chemosis and eye swelling. Ophthalmology and neurology were consulted after detailed physical examination and diagnostic workup including laboratory analysis, imaging and lumbar puncture. The patient was diagnosed with non-specific orbital inflammation and was started on methylprednisolone and dorzolamide–timolol for intraocular hypertension. The patient’s condition improved slightly, but a week later, she developed subconjunctival haemorrhage in the right eye, which prompted investigation for a low-flow carotid-cavernous fistula. Digital subtraction angiography showed bilateral indirect carotid-cavernous fistula (Barrow type D). The patient underwent bilateral carotid-cavernous fistula embolisation. Her swelling improved considerably on day 1 after the procedure and her diplopia improved over the following weeks.