Learning Objectives:

Introduction: If poor postoperative aeration can be accurately predicted, canal wall down tympanoplasty or obliteration technique is preferable to canal wall up tympanoplasty (CWUT) is described, however, little is known about the dynamics of middle ear aeration. We sought to determine how the aeration levels changed during the first- and second-stage operations (1^stSOP and 2^ndSOP), and the most recent CT examinations (recent CT).

Methods: Our study was included 50 ears which had a cholesteatoma extending into the antrum or mastoid cavity involving the ossicular chain with varying degrees of scutum defect. Middle ear aeration was assessed during 1^stSOP and 2^ndSOP, and recent CT which was performed at least 5 years subsequent to the 2^ndSOP. Middle ear aeration was graded using the following scale: 0, no aeration in the middle ear; 1, only the mesotympanum is aerated; 2, the entire tympanic cavity, including the attic, is aerated; and 3, the tympanic and mastoid cavities are aerated. The staged CWUT with mastoid cortex plasty was selected for 23 ears with grade 3 aeration (well-aerated ears group) during 2^ndSOP, the staged CWUT with bony mastoid obliteration for 27 ears with grade 0~2 aeration (poorly-aerated ears group).

Results: Aeration between 1^stSOP and 2^ndSOP was improved in 70% of all. Then, by mastoid cortex plasty, 91% of grade 3 ears during 2^ndSOP maintained that level up to recent CT. By bony mastoid obliteration, 69% of grade 2 ears and 90% of grade 1 ears maintained their aerations. A deep pocket formation occurred in 0% of grade 3 and 2 ears, 20% of grade 1 ears and 33% of grade 0 ears. There was no significant group difference in aeration level during 1^stSOP, and the proportion of the two groups during 2^ndSOP was 48% vs. 47%.

Conclusions: Staging is instructive for understanding long-term changes in aeration status. The selection of mastoid cortex plasty or bony mastoid obliteration is suitable and reliable for stabilizing postoperative aeration levels.