Unilateral proptosis & bilateral 6th nerve palsy is seen in-

Ans. is 4a' i.e., Cavernous sinus thrombosis Cavernous sinus thrombosiso The cavernous sinus is a cavity at the base of the brain that contains a vein, several nerves, and other structures,o The vein and cavity run between the large bone at the base of the skull (sphenoid bone) and temporal bone (near the temple), therefore infection to cavernous sinus can spread from the sinuses, teeth, ears, eyes, noses or skin of the face.o Routes of spread includeEthmoid sinus (most common) via ophthalmic veinsSphenoid sinus by direct spreadFrontal sinus via supraorbital and ophthalmic veinsOrbit by ophthalmic veinsUpper lid via Angular vein and ophthalmic veinsEar by petrosal venous sinusesClinical features of cavernous sinus thrombosiso Onset is abrupt with chills and rigoro It is bilateralo Involvement of IIIrd, IVth, Vth and VIth cranial nerveo Cbemosis of conjunctivao Proptosis of the eye with limited movementso Papilloedemao Pupils are dilated and fixedo Decreased visiono Decreased sensation in distribution of Vth nerve (ophthalmic division)o Progressive ophthalmoplegia (specially for lateral gaze)