抄録
An observatory study was performed on 40 temporal bones with perforated tympanic membrane.
In cases where the epidermis of external auditory canal invaded to the middle ear cavity, many central perforations were observed; as a result, it was considered that central perforation is not always benign. Encroachment of mucosa of middle ear upon the external ear canal, which has been thought to be exceptional, was also found in about 20%, prooving it was not rare.
Loose tubing should be avoided because it may induce epidermic invation of middle ear.
