(b) The general condition of the patient may be excellent, but otorrhœa or a fistula over the mastoid process may persist. Continuance of otorrhœa, in spite of healing of the wound posteriorly, means that although the disease involving the mastoid process has been eradicated, yet the walls of the tympanic cavity are themselves involved. This will probably necessitate the subsequent performance of the complete mastoid operation.
On the other hand, the suppuration may cease from the middle ear with complete recovery of hearing, and yet a fistula of the mastoid may remain. This means that all the diseased bone has not been removed. This should now be done.
TREATMENT OF SPECIAL CONDITIONS
In an infant. In an infant under two years of age the incision should be somewhat higher than usual. In making it, too much pressure should not be used, as the bone is frequently thin at this age, and if carious it may be so soft that the knife may possibly enter the intracranial cavity. In exposing the area of operation, it must be remembered that the posterior root of the zygoma and the antrum lie at a much higher level than in the adult. The opening into the antrum, therefore, is made almost above rather than behind the margin of the auditory canal. In these cases a fistula is usually present, and the bone is so soft that it can generally be removed by means of a sharp spoon or curette. At the same time, however, the aditus should be exposed and the opening made funnel-shaped in order to allow of proper dressing.
Subperiosteal abscess. The treatment depends on the extent of the abscess. If it be small, the lining membrane may be dissected away, the wound being afterwards treated in the ordinary manner. If the abscess cavity extends upwards towards the parietal region, or forwards along the temporal fossa, then drainage tubes should be inserted, their ends being brought out into the mastoid wound. It is rarely necessary to make counter-incisions. The completion of the operation is seldom difficult, as the fistula actually leads into the antrum. If the fistula be a large one and the bone is carious a sharp spoon may be used; otherwise a gouge is necessary.
Bezold’s mastoid abscess. If the lower portion of the mastoid process be composed of large cells, the abscess within the mastoid may break through the bone at its inner surface in the region of the digastric fossa. In consequence of this the pus may infiltrate the neck tissues beneath the fascia of the sterno-mastoid muscle and form a large abscess recognized clinically as a hard and painful swelling situated below the mastoid process instead of over it. This condition was first described by Bezold.
After exposing the antrum in the ordinary way, the tip of the mastoid process is opened freely. It is usually found to contain large cells filled with pus. Any granulation tissue is curetted away and the cavity dried. The inner surface of the bone is then inspected carefully in order to find the opening, which usually leads into the digastric fossa. The margins of the fistula should be curetted freely and the opening enlarged, if necessary. If the deep-lying cervical abscess be large, the finger may be passed into the abscess cavity behind the mastoid process, between it and the cut fibres of the sterno-mastoid muscle. In this way the limits of the cavity can be made out, and any septa forming pockets within it can be broken down. A counter-incision should be made through the tissues of the neck at the lower limit of the abscess. The opening should be sufficiently large to permit the insertion of a large drainage tube into the cavity. If the abscess be small it may not be necessary to make a counter-opening, but merely to insert a drainage tube into it, passing it from above downwards along the passage made by the finger.
Necrosis. In children necrosis of the temporal bone is not uncommon, especially if the middle-ear suppuration occurs in the course of a specific fever or is the result of tuberculous infection.
The part usually affected is the lower margin of the squamous portion of the temporal bone and the tympanic ring. Sometimes, however, the necrosis is very extensive, involving a large area of the petrous bone, including the labyrinth. These cases are always grave, and if a fatal result occurs it is usually in consequence of meningitis.