This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: ENT
[{'content': 'Unilateral proptosis & bilateral 6th nerve palsy is seen in - \nSelect and explain. \nA. Cavernous sinus thrombosis, B. Meningitis, C. Hydrocephalus, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Cavernous sinus thrombosis\n\nThe cavernous sinus is a cavity at the base of the brain that contains a vein, several nerves, and other structures.\nThe vein and cavity run between the large bone at the base of the skull (sphenoid bone) and temporal bone (near the temple),\xa0therefore infection to cavernous sinus can spread from the sinuses, teeth, ears, eyes, noses or skin of the face. \n\nRoutes of spread include\ni. Ethmoid sinus (most common) via ophthalmic veins\nii. Sphenoid sinus by direct spread\niii. Frontal sinus via supraorbital and ophthalmic veins\niv. Orbit by ophthalmic veins\nv. Upper lid via Angular vein and ophthalmic veins\nvi. Ear by petrosal venous sinuses \nClinical features of cavernous sinus thrombosis\n\nOnset is abrupt with chills and rigor \nIt is bilateral\nInvolvement of III rd, IV th, V th and VI th cranial nerve\nChemosis of conjunctiva\nProptosis of the eye with limited movements\nPapilloedema\nPupils are dilated and fixed\nDecreased vision\nDecreased sensation in distribution of Vth nerve (ophthalmic division)\nProgressive ophthalmoplegia (specially for lateral gaze)', 'role': 'assistant'}]