Sinus tympani: retrofacial approach for the removal of cholesteatomas.

The epithelium basement membrane of cholesteatomas in cases of chronic otitis media often extends into the sinus tympani. In the majority of cases it can be safely and completely removed by dissection through the ear canal and tympanum. In 2% of cases, not all squamous epithelium basement membrane can be removed because the sinus tympani extends more than 3 or 4 mm posterior to the anterior edge of the facial nerve and because the membrane is adherent to the irregular bony surface. Surgical exposure of the sinus tympani through the mastoid posterior and medial to the facial nerve allows complete removal of all basement membrane with a direct view. The technique using a retrofacial approach to expose this obscure sinus is described and a series of 48 cases treated successfully by this method are reported.