Question:medium
A patient had a running nose and pain over the medial aspect of the eye and was being treated with decongestants for many days. He later developed chemosis, proptosis and diplopia on abduction of the right eye with congestion of the optic disc. What is the probable diagnosis?
A patient had a running nose and pain over the medial aspect of the eye and was being treated with decongestants for many days. He later developed chemosis, proptosis and diplopia on abduction of the right eye with congestion of the optic disc. What is the probable diagnosis?
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Facial/nasal sepsis spreading back, plus chemosis, proptosis, CN VI palsy and a congested disc, means the cavernous sinus.
Updated On: Jun 24, 2026
- Acute ethmoidal sinusitis
- Orbital cellulitis
- Cavernous sinus thrombosis
- Orbital apex syndrome
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The Correct Option is C
Solution and Explanation
Read this as an infection that travelled. It began in the nose and medial orbit (ethmoidal/facial territory) and was never properly treated, only masked with decongestants. The face and orbit drain through valveless veins, so pus can flow backward into the cavernous sinus and clot it.
Then check what the cavernous sinus would do if it thromboses. Two things: it dams the venous blood returning from the orbit, and it squeezes the cranial nerves passing through it. The dammed venous outflow gives chemosis, proptosis and a congested, swollen optic disc. The nerve compression gives ophthalmoplegia, and because the abducens (CN VI) sits most medially and most exposed inside the sinus, a failure of abduction (the lateral rectus) is the typical early eye-movement sign, exactly the diplopia on abduction described.
Compare the runners-up. Isolated ethmoidal sinusitis is just nasal disease, with no nerve palsy and no disc congestion. Orbital cellulitis can proptose the eye but does not typically produce the venous disc congestion and cranial nerve pattern of a sinus thrombosis, and orbital apex syndrome would not be preceded by a spreading septic facial focus with such marked venous congestion. The complete septic-plus-venous-plus-CN-VI picture is cavernous sinus thrombosis.
\[\boxed{\text{Cavernous sinus thrombosis}}\]
Then check what the cavernous sinus would do if it thromboses. Two things: it dams the venous blood returning from the orbit, and it squeezes the cranial nerves passing through it. The dammed venous outflow gives chemosis, proptosis and a congested, swollen optic disc. The nerve compression gives ophthalmoplegia, and because the abducens (CN VI) sits most medially and most exposed inside the sinus, a failure of abduction (the lateral rectus) is the typical early eye-movement sign, exactly the diplopia on abduction described.
Compare the runners-up. Isolated ethmoidal sinusitis is just nasal disease, with no nerve palsy and no disc congestion. Orbital cellulitis can proptose the eye but does not typically produce the venous disc congestion and cranial nerve pattern of a sinus thrombosis, and orbital apex syndrome would not be preceded by a spreading septic facial focus with such marked venous congestion. The complete septic-plus-venous-plus-CN-VI picture is cavernous sinus thrombosis.
\[\boxed{\text{Cavernous sinus thrombosis}}\]
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