A 40-year-old woman develops proptosis, complete ophthalmoplegia, and anaesthesia in the V1 distribution over three days. Visual acuity is 6/6 in both eyes, pupils react normally, and the fundi are healthy. MRI shows inflammatory change localised to the right superior orbital fissure. The most likely diagnosis is:

• A Orbital apex syndrome
• B Carotid cavernous fistula
• C Superior orbital fissure syndrome ✓
• D Cavernous sinus thrombosis

Explanation

The oculomotor, trochlear, abducens nerves and the ophthalmic division of the trigeminal all traverse the superior orbital fissure, producing ophthalmoplegia and V1 sensory loss when it is diseased. Vision is preserved because the optic nerve runs in the separate optic canal. Involvement at the orbital apex adds optic neuropathy with visual loss. A fistula gives pulsatile proptosis with a bruit, and cavernous sinus thrombosis adds systemic toxicity.

Reference: Kanski's Clinical Ophthalmology, 9th ed.

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Written and medically reviewed by the StethoPrep medical team.