Postoperative Mastoid Aeration Following Canal Wall Up Mastoidectomy according to Preoperative Middle Ear Disease: Analysis of Temporal Bone Computed Tomography Scans

BACKGROUND AND OBJECTIVES: The aim of our study was to evaluate postoperative mastoid aeration according to the preoperative middle ear disease and investigate the factors affecting it. SUBJECTS AND METHODS: We retrospectively reviewed the high-resolution computed tomography (CT) scans of temporal bones that were taken 1 year after surgery. The postoperative mastoid aeration was evaluated according to the preoperative diagnosis, and classified into three groups: grade 1 (complete mastoid aeration), an air-filled epitympanum and mastoid cavity; grade 2 (partial mastoid aeration), an air-filled epitympanum and partially aerated mastoid cavity; and grade 3 (absence of mastoid aeration), no air space in the mastoid cavity. RESULTS: The overall mastoid aeration rate was 55.8%, with adhesive otitis media accounting for 21.2%, attic cholesteatoma 53.8%, and chronic otitis media 75.4%. The rates of postoperative mastoid aeration were significantly higher in the chronic otitis media cases and attic cholesteatoma cases than in the adhesive otitis media cases. There were 14 cases requiring revision operations due to the development of a retraction pocket in the tympanic membrane. All of the revised cases had grade 3 postoperative mastoid aeration, and underwent canal wall down mastoidectomies. CONCLUSIONS: The degree of postoperative mastoid aeration is associated with the preoperative middle ear disease. When planning a canal wall up mastoidectomy, the surgeon should contemplate the middle ear disease, because a canal wall down mastoidectomy or mastoid obliteration is recommended if the patient has adhesive otitis media.