Cavernous sinus spread from maxillary infection — ORE Part 1 MCQ

Correct answer: D — Facial venous drainage (angular vein to ophthalmic vein) lacks effective valve protection, allowing retrograde spread to the cavernous sinus

Explanation lettering: C = shown as B · B = shown as C · E = shown as D · D = shown as E

The correct answer is E. Maxillary dental infections can spread intracranially via a specific venous route: infection drains through the facial venous plexus (particularly the angular vein), which communicates with the superior ophthalmic vein; the ophthalmic vein then drains into the cavernous sinus. While recent anatomical literature shows that ophthalmic and facial veins are not entirely valveless, they have minimal or absent valve protection in key tributary vessels (notably the inferior ophthalmic vein), allowing retrograde blood flow and infection spread—especially when intra-orbital venous pressure rises due to infection and inflammation. This mechanism explains why the patient develops periorbital swelling and diplopia (cranial nerve compression within the cavernous sinus). Distractors A and D are anatomically incorrect (lymphatic and PDL pathways do not reach the cavernous sinus). B is false (parotid duct opens into the mouth, not intracranially). C confuses arterial with venous pathways and involves the wrong artery. The hard difficulty lies in recognising the specific facial-to-ophthalmic-to-cavernous sinus route and understanding the physiological basis (valve insufficiency) that makes it dangerous.

Reference: Anatomy, Head and Neck: Eye Ophthalmic Vein. StatPearls Publishing, 2020. https://pubmed.ncbi.nlm.nih.gov/32491535/; Zhang J, Stringer MD. Ophthalmic and facial veins are not valveless. Clinical & Experimental Ophthalmology. 2010;38(5):502–510. https://pubmed.ncbi.nlm.nih.gov/20491800/