Pathophysiology of the gas exchange function of the middle ear mucosa after surgery, efficacy of a largesized silicone film upon recovery of mastoid aeration after mastoidectomy, and indication of mastoid obliteration in combination with the “soft-wall reconstruction” of the posterior ear canal wall were described. The mucosa in the middle ear, especially in the mastoid, has gas exchange function, contributing to the pressure regulation in the middle ear, but the function is usually lost after mastoidectomy. Placement of a large-sized silicone film covering from the eustachian tube to the mastoid antrum after mastoidectomy helped recovery of mastoid aeration in more than half of the patients. Particularly, when a tympanostomy tube was placed in addition to it, the recovery rate was better. Since the posterior canal wall retracts towards the mastoid after mastoidectomy in patients being operated with the soft-wall reconstruction of the posterior ear canal wall, mastoid obliteration with a smooth material such as bone pate is recommended in case of one-stage operation when the mastoidectomized cavity is large. Whereas, in two-stage operation, even if the cavity is large, placement of a large-sized silicone film is worth being tried expecting recovery of the mastoid aeration.
