Patient is suffering from cavernous venous thrombosis, as a complication of chronic ethmoidal sinusitis. The facial veins make clinically impoant connections with the cavernous sinus through the superior ophthalmic veins. Cavernous sinus thrombosis usually results from infections in the orbit, nasal sinuses, and superior pa of the face. Think Detail: Cavernous sinus: is located on the side of the body of sphenoid. The cavernous sinuses consist of extradural venous plexuses surrounded by a dural fold. Structures Within its cavity Internal carotid aery Abducent nerve Carotid sympathetic plexus Lateral wall Oculomotor nerve Trochlear nerve Opthalmic division of trigeminal nerve Maxillary division of trigeminal nerve Tributaries: Anteriorly Opthalmic veins (connects with the facial vein) Posteriorly Superior petrosal sinus (connects with transverse sinus) Inferior petrosal sinus (conncets with internal juglar vein) Medially Anterior and posterior intercavernos sinuses (connects the two cavernous sinuses) Superiorly Superficial middle cerebral vein (from latwral surface of the brain) Cerebrsl veins from inferior surface of brain Cavernous sinus thrombosis (CST) is a late complication of facial or paranasal sinus infection, resulting in thrombosis of the cavernous sinus and inflammation of its surrounding anatomic structures, including cranial nerves. Clinical features: Infection of the cavernous sinus is characterized by sepsis, orbital pain, chemosis, proptosis, and ophthalmoplegia. Cavernous sinus thrombosis results in paresis of cranial nerves III, IV, and VI and the opthalmic and maxillary divisions of the cranial nerve V. The diagnosis is based primarily on clinical data. CT and MR imaging can provide diagnostic information.Treatment is with broad spectrum antibiotics and should be staed early .This has high moality. Cavernous sinus syndrome: is characterized by multiple cranial neuropathies. The clinical presentation includes impairment of ocular motor nerves, Horner's syndrome, and sensory loss of the first or second divisions of the trigeminal nerve in various combinations. The pupil may be involved or spared or may appear spared with concomitant oculosympathetic and parasympathetic involvement. Ref: 1) Comprehensive opthalmology,by AK Khurana,4th Edition, Page 384-389; 2) Parsons ' Diseases of the Eye, 20th Edition, Page 456-459;