====== Cavernous sinus thrombosis ====== [[Cavernous sinus]] [[thrombosis]] (CST) is the formation of blood clot within the cavernous sinus, a cavity at the base of the brain which drains deoxygenated blood from the brain back to the heart. The cause is usually from a spreading infection in the nose, sinuses, ears, or teeth. see [[Septic cavernous sinus thrombosis]]. Cavernous sinus thrombosis symptoms include a decrease or loss of vision, chemosis, exophthalmos (bulging eyes), headaches, and paralysis of the cranial nerves which course through the cavernous sinus.