OPERATIONS FOR ATRESIA
Atresia of the external meatus may be either congenital or acquired.
Indications. (i) In congenital cases operation is only justifiable if the atresia is due to a membranous web situated in the outer part of the auditory canal and if, as a result of tuning-fork tests and of inflation through the Eustachian tube, it is fairly certain that the middle ear is normal.
Operation is contra-indicated in cases of bony atresia. Although attempts have been made to make an artificial canal in order to restore the hearing power, a successful result has not yet been obtained. Apart from the difficulty of retaining the patency of any canal so made, the accompanying malformation of the middle ear renders a successful result impossible (Paper by author, Journal of Laryngology, &c., March, 1901). Although the tympanic membrane is said to have been exposed by operation in a few cases, experience has shown that the supposed tympanic membrane was really the capsule of the temporo-maxillary joint.
(ii) In acquired cases operation is indicated if the other ear is deaf; if the site of the occlusion of the auditory canal is in its outer part and is due to membranous or fibrous tissue, and if there is no previous history of middle-ear disease, and if the labyrinth is still intact.
Operation is not advised if the other ear is normal, unless the patient particularly desires it.
Operation is contra-indicated if there is internal-ear deafness on the affected side and if the other ear is normal; or if there is a definite history of the closure of the auditory canal having been the result of a previous middle-ear suppuration. In the latter case the destructive changes within the tympanic cavity will be so marked that the chances of improving the hearing will be very slight in spite of the most successful operation.
Operation. If the obstruction be due to a fibrous band, an attempt may be made to remove it by excising it by the intrameatal method. In other cases the post-auricular method is necessary.
The chief point to remember is to make a large opening. For this reason the post-auricular method is to be preferred, as a considerable portion of the upper posterior wall can be removed and a large meatal flap fashioned (see [p. 401]).