Cavernous sinus thrombosis
Cavernous sinus thrombosis is a blood clot in the cavernous sinuses. It can be life-threatening.
The most common initial symptom of cavernous sinus thrombosis is a headache.
Cavernous sinus thrombosis is usually caused by a bacterial infection that spreads from another area of the face or skull.
About 1 in 3 people with cavernous sinus thrombosis die, and many people who survive it go on to develop further problems.