[Sinus tympani in surgery of the middle ear and skull base].

Tympanic sinus is located at the medial wall of the tympanic cavity. It's visualisation is difficult from most of approaches. Tympanic sinus is often filled with cholesteatoma in course of chronic otitis. Intraoperative assessment of tympanic sinus was performed in 29 patients with facial recess cholesteatoma, and in 20 patients with acoustic neuroma operated with translabyrinthine approach. In the group of patients with cholesteatoma four patients underwent canal wall up tympanoplasty with posterior tympanotomy, 25 underwent canal wall down tympanoplasty. Tympanic sinus was assessed during surgery with 30 degrees endoscope. In all cases depth of the sinus was measured with the use of calibrated hook. In 11 patients depth of the sinus exceeded 4 mm. In 6 among these features of bone destruction was found.