Unless contra-indicated, a general anæsthetic should be given, as it is not always possible to foretell whether the operation will be difficult or easy. In addition it may be necessary to curette out granulations and also to remove the outer wall of the attic. Unless the patient is very insensitive, this is almost impossible under local anæsthesia (see [p. 311]).
Before the anæsthetic is given, the ear should be filled with a 5% solution of cocaine containing a 1 in 2,000 solution of adrenalin chloride in order to diminish the bleeding during the operation.
The field of operation is isolated from the surrounding parts by covering the head with a sterilized towel having an opening cut in it just sufficient to expose the auricle and meatus.
The following are the steps of the operation: (1) freeing the malleus from its attachments to the tympanic membrane, and from the inner wall of the middle ear, if adherent to it; (2) cutting through the tendon of the tensor tympani muscle; (3) removal of the malleus; (4) removal of the incus; (5) removal of the outer wall of the attic; (6) curetting out of granulations, if present. The method of operation varies slightly according to the condition found.
Removal of the malleus. In post-suppurative and non-suppurative conditions the chief cause of failure is the recurrence of adhesions, so for this reason it is wisest to remove the membrane as completely as possible.
With a paracentesis knife, the membrane is incised below and behind the malleus. The incision is then carried upwards along its posterior border to the posterior fold, then round the complete margin of the tympanic membrane and along the anterior fold and border of the malleus, so as to meet the original point of the incision. The knife is then reinserted just in front of the processus brevis and cuts through the anterior ligament in an upward direction; in a similar fashion the posterior fold is also cut through ([Fig. 190]).
The next step is tenotomy of the tensor tympani muscle (see [p. 345]).
The malleus thus freed can easily be removed by seizing its handle with a pair of Sexton’s ([Fig. 193]) or crocodile forceps ([Fig. 179]). In removing the malleus it is necessary to remember that its head is situated within the attic and therefore cannot be pulled out directly, but must first be drawn downwards until it is seen within the tympanic cavity. If this precaution be not taken, the neck of the malleus may be broken, leaving the head behind. If this takes place its extraction may be a matter of difficulty.
| Fig. 199. Removal of the Malleus by Wilde’s Snare. First position. After cutting through the tensor tympani muscle by Schwartze’s method. | Fig. 200. Removal of the Malleus by Wilde’s Snare. Second position. Malleus pulled down from attic—about to be withdrawn from auditory canal. |
Instead of using Sexton’s forceps, the malleus may be removed by means of Wilde’s snare. This is the method advocated by Schwartze. After cutting through the tensor tympani muscle, the loop of the snare is threaded over the head of the malleus and guided upwards until it embraces its neck. The loop is then drawn tight so as to hold the malleus firmly in its grasp. The ossicle is extracted by first pulling it downwards (Fig. 199), so as to dislodge it from the attic, and then outwards (Fig. 200).