A patient presents with difficulty moving the eye, proptosis, fever, and a history of an untreated maxillary dental infection. What is the MOST likely diagnosis?

Correct answer: B. Cavernous sinus thrombosis

• A. Ludwig angina is a bilateral submandibular, sublingual, and submental space infection of mandibular origin, threatening the AIRWAY rather than the eye.
• B. CORRECT. OPHTHALMOPLEGIA (impaired eye movement) is the defining sign, because cranial nerves III, IV, and VI run through or along the cavernous sinus. Add proptosis, chemosis, periorbital swelling, a fixed dilated pupil, fever, and altered consciousness, and the picture is CAVERNOUS SINUS THROMBOSIS — a life-threatening complication of odontogenic infection spreading via the VALVELESS angular and ophthalmic veins or the pterygoid plexus. This is an immediate hospital transfer for IV antibiotics and neurosurgical/ophthalmologic care.
• C. Orbital cellulitis also causes proptosis and painful eye movement, but the presence of cranial nerve palsies, bilateral signs, and altered mental status indicates intracranial extension.
• D. Sinusitis causes facial pressure and nasal discharge without ophthalmoplegia.

Note: The danger triangle of the face drains backward through valveless veins to the cavernous sinus. That single anatomic fact explains this entire emergency.