Thrombophlebitis of the facial vein, (inflammation of the facial vein with secondary clot formation) can result in pieces of an infected clot extending into the cavernous sinus, forming thrombophlebitis of the cavernous sinus.
Inflammation of the facial vein, accompanied by secondary clot formation, can lead to fragments of an infected clot entering the cavernous sinus, causing thrombophlebitis of the cavernous sinus.