Cavernous Sinus Thrombosis (CST) is a serious medical condition that has the potential to cause vision loss, seizures, and even death. It is caused by a blood clot forming in the cavernous sinus, which is a small space located behind the eyes and below the brain. There are a number of synonyms for CST, including cavernous sinus thrombophlebitis, sphenoparietal sinus thrombosis, and petrosal sinus thrombosis. Regardless of the name used to describe it, CST requires immediate medical attention to prevent serious complications and minimize the risk of permanent damage. If you experience symptoms such as severe headache, eye pain, or changes in vision, seek medical attention right away.