Learning Objectives: Endoscopic assisted surgery for petrous bone cholesteatoma can be used safely.

Objective: The petrous bone cholesteatoma (PBC) is used to describe an epidermoid cyst of the petrous portion of the temporal bone. Sanna et al have classified PBCs into five groups: supralabyrinthine, infralabyrinthine, infralabyrinthine-apical, massive, and apical. Besides, these terms describe both the extent of the lesion and the location.

The appropriate surgical procedure for PBC is frequently radical surgical removal such as the labyrinthectomy and/or rerouting of the facial nerve. However, it may have to be modified, depending on the status of the contralateral ear. Therefore, location and extend of the pathology is defined to adequate surgical approach with modification. Recently, some studies have described to “minimally invasive cholesteatoma removal” which were aimed to preserve hearing and facial nerve functions for treatment of the PBC.

Methods: We performed standard middle fossa craniotomy to access to petrous apex. Otomicroscope was used to remove the most part of the cholesteatoma, but in some hidden area such as infralabyrinthine area, medial part of the carotid artery, endoscope (4 mm 0 or 45 degree) was used.

Results: Here we present 4 cases with infralabyrinthine-apical cholesteatoma who underwent endoscopic assited surgery via middle fossa approache. We were able to preserve hearing in 2 patients. In another 2 patients, labrinth was already invaded by cholesteatoma and the hearing was not able to preserved.

Conclussion: Endoscopic assisted surgery via middle fossa approache can be help removal of infralabyrinthine-apical or massive without cochlear resection, labyrinthectomy and facial nerve injury. Moreover, it may help to reduce the residual cholesteatoma mostly in hidden recess.