Part 57 (1/2)

(i) _Adhesion of the handle of the malleus to the promontory._ With a paracentesis knife the membrane is incised round the handle of the malleus (Fig. 191). A small sickle-shaped knife, fixed at right angles to its shaft, is then inserted through the incision (in front of or behind the malleus as may be most convenient to the operator) and is made to cut through the adhesions between the malleus and the promontory (Fig. 192). In order to make sure that this has been accomplished, a small ring-knife, such as is used in the operation of ossiculectomy, is pa.s.sed round the tip of the malleus, between it and the inner wall of the promontory, and slight traction is then exerted in order to pull the handle of the malleus outwards from the inner wall.

[Ill.u.s.tration: FIG. 192. FREE EDGE OF TYMPANIC MEMBRANE CUT THROUGH. A, Surface view; B, Vertical section. _a_, Malleus adherent; _b_, Membrane adherent; _c_, Free edge of membrane; _d_, Spatula freeing membrane.]

Provided asepsis has been maintained, this small operation seldom gives rise to any inflammatory reaction. The after-treatment consists in inserting a strip of gauze into the auditory ca.n.a.l; if it becomes moist with secretion, it should be changed.

Many methods have been devised to prevent recurrence of adhesions, but few are successful. Amongst these are daily inflation of the ear by means of Politzer's method or the catheter; the injection of oil into the middle ear; and the insertion of small pieces of celluloid between the malleus and inner wall of the promontory according to the method of Gomperz. Another method is to _resect the handle of the malleus_ (Fig.

195). After being freed from the promontory as above described, the manubrium is cut through with a pair of fine scissors (Fig. 174) just below the processus brevis, and the lower fragment is removed by means of s.e.xton's forceps (Fig. 193).

(ii) _Adhesion between the membrane and the inner wall of the tympanic cavity._ Siegle's speculum should be used to determine the position and extent of the adhesions (Fig. 194).

[Ill.u.s.tration: FIG. 193. s.e.xTON'S INSTRUMENT. A, For removal of a foreign body; B and C, For removal of the malleus; D, Scissors.]

There are two methods of operation:--

(_a_) In the case of bands forming a bridle between the tympanic membrane and inner wall, an attempt may be made to cut through them.

This is done by incising the membrane with a paracentesis knife in front of or behind the adherent portion, and then inserting through this incision the sickle-shaped knife. By rotating it upwards or downwards, as the case may be, the bands forming the adhesions are cut through. If this has been successfully performed, and if the retraction of the membrane was solely due to these bands, the tympanic membrane will be found to be freely movable on diminis.h.i.+ng the pressure of air within the external meatus by means of Siegle's speculum.

(_b_) If the adhesions be extensive, the only method affording a chance of success is to separate the free portion of the tympanic membrane from the part adherent to the inner wall, leaving the latter _in situ_. To do this the membrane is incised with a paracentesis knife just beyond the margin of the adherent portion, the incision being carried right round the affected part. A tiny spatula, bent at right angles to its shaft, is then inserted through the incision and pa.s.sed round beneath the movable portion of the membrane so as to free it completely (Fig. 192).

[Ill.u.s.tration: FIG. 194. METHOD OF USING SIEGLE'S SPECULUM.]

(iii) _Adhesion of the edge of a perforation to the inner wall._ If the middle-ear suppuration has only recently ceased, it may be sufficient to divide the adhesion with a small knife curved on the flat and afterwards force the tympanic membrane outwards by means of inflation through the Eustachian tube, and by rarefaction of the air within the external meatus. In the majority of cases, however, it is necessary to excise the adhesion, especially in the more chronic conditions. This is done by cutting through the movable part of the membrane just beyond the adherent portion (_vide supra_).

[Ill.u.s.tration: FIG. 195. DIVISION OF INTRATYMPANIC ADHESION WITH EXCISION OF HANDLE OF MALLEUS. A, Surface view; B, vertical section.

_a_, Remains of malleus (handle already excised); _c_, Free edge of membrane; _d_, Scar tissue on promontory, at which point malleus and membrane were previously adherent.]

(iv) _Adhesions surrounding the articulation between the incus and stapes, and the stapes itself._ These adhesions can only be observed if a large perforation involves the upper posterior quadrant. Even then it may be anatomically impossible to see the stapes. The operation should only be performed if definite bands of adhesions can be seen. Sometimes, although rarely, it happens that such adhesions are present. If the incudo-stapedial joint be fixed to the inner wall of the tympanic cavity, the adhesions are separated from it by pa.s.sing the knife between the joint and the inner wall. In order to cut through adhesions surrounding the base of the stapes, a small horizontal incision should be made along its upper margin, and also along the lower, if this is in view. This operation, however, is seldom of any value.

TENOTOMY OF THE TENSOR TYMPANI

=Indication.= The chief indication for this operation is marked retraction of the tympanic membrane, in a case of middle-ear deafness, in which there are no adhesions between the membrane and the inner wall of the middle ear, and in which it is a.s.sumed that the retraction is due to shortening of the tensor tympani muscle.

=Operation.= The first step of the operation is to incise the tympanic membrane with a paracentesis knife in a vertical direction just behind the margin of the malleus. At the same time the posterior fold can be cut through, if required, by continuing the incision upwards. Through the incision thus made Schwartze's tenotomy knife (a very fine blunt-pointed instrument curved on the flat (Fig. 196)) is inserted, its point being directed upwards. The knife is pushed upwards until its shaft is on a level with the processus brevis. The handle is then rotated in a forward direction so that the sharp edge of the knife, which is kept close to the posterior border of the neck of the malleus, makes a circular movement forwards and downwards and thus cuts through the tendon of the muscle. If the knife has been too deeply inserted, the attempt to rotate the shaft forwards will be resisted by the projecting processus cochleariformis. To overcome this difficulty the shaft of the instrument is rotated backwards so as to raise the point of the tenotomy knife and thus free it; the instrument is then withdrawn slightly and the shaft again rotated forwards. The division of the tendon can be distinctly felt, and may be accompanied by a slight crackling noise; after this has been effected, the knife is rotated backwards and withdrawn through the incision in the tympanic membrane.

[Ill.u.s.tration: FIG. 196. SCHWARTZE'S TENOTOMY KNIFE.]

=After-treatment.= There is usually a slight effusion of blood within the tympanic cavity, but no special treatment is required beyond keeping the ear aseptic. Absorption takes place rapidly.

The _result_ of the operation is disappointing. There is seldom any improvement with regard to hearing; a few cases, however, have been reported in which the attacks of vertigo have diminished in intensity.

TENOTOMY OF THE STAPEDIUS

=Indications.= They are limited.

(i) As the result of middle-ear suppuration the malleus and incus may become exfoliated. The theory has been advanced that the unopposed action of the stapedius muscle prevents free movement of the stapes in these cases, and for this reason tenotomy of its tendon is advocated.

This operation, however, should only be performed provided that the edge of the membrane is not adherent to the inner wall of the tympanic cavity, and there is no internal-ear deafness.