Modified classification of infralabyrinthie cholesteatoma and scale of cholesteatoma extention

Introduction. Petrous temporal bone (PTB) cholesteatoma is an epidermal cyst, which is the result of uncontrolled growth of keratinizing squamous epithelium in the petrous part of the temporal bone. Cholesteatoma is classified into congenital, acquired, and iatrogenic.Objective. To discuss the classification of infralabyrinthine petrous bone cholesteatoma (PBC), add modified classificationand to propose adequate differential surgical management.Methods. The setting was a National Medical Scientific Center of Otorhinolaryngology FMBA (Russia). The data of 14 patients who underwent surgery for different variations of infralabyrinthine PBC from 2017 till 2020 were analyzed and included into the study (with respect to localization type of the approach used, complications, recurrences and outcome). The follow-up period ranged from 6 to 34 months with a median of 18 months.Results. Based on preoperative CT scans and intraoperative findings a Scale of Cholesteatoma extension CLIF(APO) and Modified classification of infralabyrinthine cholesteatoma (in relation to mastoid segment of the facial nerve) are proposed. The scale includes the main anatomical structures of the temporal bone and the adjacent parts of the occipital and sphenoid bones, which may be involved in the cholesteatoma process: cochlea, vestibule and semicircular canals, internal auditory canal, jugular foramen, bony chanal of the internal carotid artery, petrous apex, occipital condyle. Based on the modified classification and scale we present an algorithm for decision making and surgical approach choosing.Conclusion. The implementation of the Scale of Cholesteatoma Extension in Otology and Radiology practice will allow to preoperatively diagnose the extension of PBC, unify the data of the localization of cholesteatoma; allows standardization in reporting and continuity at all stages of treatment. The modified classification proposed by us in this article facilitate the algorithm for selecting the type of surgical approach and determine whether to perform less aggressive combined microscopic approaches with endoscopic control.