CHAPTER VI

THE COMPLETE MASTOID OPERATION

Before considering the question of the radical operation, it is a.s.sumed that conservative treatment has been attempted and has failed, and that the middle-ear suppuration has existed for a considerable period.

=Indications.= (i) As a prophylactic measure. If there be merely a perforation of the tympanic membrane and no evidence of disease of the ossicles nor the walls of the tympanic cavity, the probability is that the continuance of the suppuration is due to an affection of the mucous membrane rather than of the underlying bone; for example, to a chronic empyema of a large antrum cavity which, owing to its anatomical structure, will not drain freely.

In such cases the complete mastoid operation is only indicated if the deafness is extreme, the bone conduction diminished, and the high tuning-forks not well heard, or if the ossicles are bound down by adhesions to the inner wall of the tympanic cavity, as it is then obvious that the hearing power cannot be restored completely.

It must, however, be remembered that in many cases a slight discharge may exist for years without giving rise to any complications. If the patient be made aware of the slight danger which exists in every case of middle-ear suppuration, and be in a position to obtain medical attention if retention of pus occurs, then operative measures may be deferred indefinitely. If, on the other hand, the patient intends going to some remote country where medical attendance is impossible, then it is probably wiser to submit to the complete operation rather than risk future trouble.

(ii) If there be recurrent attacks of giddiness, nausea, or headaches radiating up the affected side which are not arrested by the ordinary methods of treatment. These symptoms of retention of pus within the antrum and mastoid process should be considered as danger signals. In this case also it is a.s.sumed that the hearing cannot be restored, and in consequence there is no object in performing Schwartze's operation.

(iii) If there be recurrence of polypi and granulations within the tympanic cavity in spite of curetting, especially if the operation of ossiculectomy has already been performed.

(iv) If there be symptoms of retention of pus due to want of free drainage in the case of stenosis of the external meatus, whether due to fibrous contraction of its soft parts, or from the presence of exostoses.

(v) If cholesteatomatous formation be present. Even if there be no symptoms necessitating immediate interference, operation is usually indicated owing to the fact that cholesteatoma is the commonest predisposing cause of intracranial suppuration and septic thrombosis of the lateral sinus.

(vi) If there be a fistula of the bony wall of the mastoid process, whether it extends anteriorly into the auditory ca.n.a.l or externally through the skin over the region of the mastoid process. It must not be forgotten, however, that simple opening of the antrum and mastoid cells will be quite sufficient if the condition is the result of a recent and acute inflammation of the mastoid process.

(vii) If there be facial paralysis occurring in the course of a chronic middle-ear suppuration. This may mean either that there is bone disease involving the facial ca.n.a.l, or that the inflammatory process has spread through the Fallopian ca.n.a.l towards the inner ear. In either case operation is indicated.

(viii) As a preliminary step in intracranial suppurative lesions of ot.i.tic origin.

(ix) In tuberculosis of the middle ear. If the patient's general condition permits of it, and if the pulmonary disease be slight or arrested, the complete operation should always be done. The difficulty is to remove all the diseased bone. If this can be done the wound will heal quite well.

(x) In acute inflammation of the mastoid process occurring in the course of chronic middle-ear suppuration, the complete mastoid operation should be performed, as in these cases the attic, aditus, and antrum are always involved.

(xi) Amongst the rarer conditions for which the complete operation may be necessary are removal of a foreign body which has been pushed inadvertently into the region of the attic and aditus and cannot otherwise be removed; and actinomycosis of the temporal bone.

METHODS OF OPERATION

The actual method of carrying out this operation varies. For those who have not had great experience the best method is first to open the antrum, as in Schwartze's operation, and then to remove the 'bridge' of bone between it and the tympanic cavity (Kuster-Bergmann operation, sometimes called the Schwartze-Stacke operation). Instead of doing this, the upper posterior part of the auditory ca.n.a.l may be chiselled away simultaneously during the act of exposing the antrum (Wolf's operation).

On the other hand, the mastoid and antrum may be exposed from within outwards by removing the outer attic wall and working backwards (Stacke's operation).

=The Kuster-Bergmann (or Schwartze-Stacke) operation.= The preliminary preparation, the position of the patient, and the instruments required are the same as in opening the antrum.

[Ill.u.s.tration: FIG. 221. THE 'RADICAL' MASTOID OPERATION. To show removal of the 'bridge' from above. The seeker, inserted into the aditus, acts as a protector to the underlying external semicircular ca.n.a.l and facial nerve.]

The =incision= is begun just above the upper insertion of the pinna, and is carried downwards in a curved direction behind the auricle along the margin of the skin and scalp. Some authorities prefer to make the incision close behind or even along the post-auricular fold. In favour of the incision being placed far back is the concealment of the scar by the hair. Also, as it is situated on healthy bone somewhat posterior to the actual wound cavity, it should heal by primary union and with no after-displacement of the auricle. In addition, if it be necessary to expose the lateral sinus, this can usually be done by simple retraction of the soft parts.

The exposure of the field of operation is the same as in the simple opening of the antrum, excepting that the soft tissues should be separated a little further forwards and above the external bony meatus, as in this operation the upper posterior wall has to be removed.

The antrum is opened as already described (see p. 382).

The fibrous portion of the external meatus is separated carefully from the posterior wall of the bony meatus by means of a periosteal elevator, and is pulled forward by a retractor. The external portion of the posterior wall is now removed in a wedge-shaped fashion by alternate strokes of the chisel from above downwards (Fig. 221) and from below upwards. The upper level of the bone to be removed corresponds with the zygomatic ridge. After a small portion has been removed, a pair of forceps is pa.s.sed into the auditory meatus and its point made to project into the wound posteriorly through the end of the now detached fibrous portion of the auditory ca.n.a.l. With the forceps a piece of gauze is drawn through the auditory meatus in the form of a loop. By its means the auricle and fibrous portion are pulled well forward, thus exposing to view the tympanic cavity. Two openings are now seen: one, the auditory ca.n.a.l and tympanic cavity, in front, and the other, the antrum and mastoid cavity, behind. Between them is the 'bridge'; that is, the innermost portion of the posterior wall of the auditory ca.n.a.l.

[Ill.u.s.tration: FIG. 222. STACKE'S PROTECTOR.]

Any granulations present are curetted away gently from the tympanic cavity. The seeker is next pa.s.sed into the tympanic cavity, and its point directed upwards and backwards into the aditus, so that it rests on the floor of the latter, or its point may be inserted into the aditus through the mastoid wound. Beneath it lies the eminence of the external semicircular ca.n.a.l and the facial nerve. This is a most important landmark. Provided the seeker is kept in this position, all the bone lying superficially to it can be removed without injury to the semicircular ca.n.a.l or facial nerve.

In this connexion may be mentioned Stacke's probe or 'protector' (Fig.

222). Although historically an instrument of importance, I do not make use of it. It is so large and of such sharp outline that, unless used with extreme care, it is itself very liable to injure the facial nerve.

For this reason I prefer the seeker, a much finer and more delicate instrument, which will serve the purpose without the same risk (Fig.

219).

The 'bridge' is now carefully removed by the gouge or chisel, frequent use being made of the seeker meanwhile. As the roof of the antrum, aditus, and attic is a continuous one, the bone to be removed is necessarily at a higher level than the roof of the bony meatus. This is a point which must not be forgotten, as the great fault of the beginner is to remove the bone too low down.

As the aditus is approached, the strokes of the chisel must be very gentle. If too much force be used, the chisel, on breaking through the innermost portion of the 'bridge', may injure the deeper-lying parts, more especially the facial nerve.

Some authorities advocate removal of the 'bridge' by means of bone forceps. This, however, is not so sure a method as by the chisel or gouge.

After removal of the bridge, the tympanic cavity, antrum, and mastoid will form a continuous cavity. As a rule the outline of the external semicircular ca.n.a.l appears as a well-marked white eminence, and projecting beyond it are the remains of the posterior wall of the auditory ca.n.a.l. In removing this ridge good illumination is essential.

The bone is removed in layers with the chisel, beginning at the tip of the mastoid process, and working parallel to the auditory ca.n.a.l and the underlying facial ca.n.a.l. If necessary the seeker may be used as a guide, its point being allowed to rest on the floor of the aditus, superficial to the semicircular ca.n.a.l (Fig. 223).

The amount of bone removed should be such that at the end of the operation the auditory ca.n.a.l is only separated from the main cavity of the mastoid antrum by a slight eminence, the remainder of the posterior wall, which is continuous with that of the external semicircular ca.n.a.l.

[Ill.u.s.tration: FIG. 223. THE 'RADICAL' MASTOID OPERATION. Showing removal of the remains of posterior wall of the auditory ca.n.a.l; the seeker acting as a protector.]

Occasionally the facial ca.n.a.l and the stylo-mastoid ca.n.a.l are abnormally superficial. Provided the bone be removed in the manner just described, the facial nerve should not be injured, even though it may be exposed inadvertently. A warning of this occurrence is given by bleeding from the vessels within the ca.n.a.l (see p. 374).

If the malleus and incus be still _in situ_, they can now be seen and can usually be removed by the curette. No force must be used. Removal of the incus is a matter of no difficulty. In the case of the malleus there may be some resistance owing to the attachment of the tendon of the tensor tympani muscle. If so, the malleus should be grasped by a fine pair of forceps and the tendon severed by means of Schwartze's tenotomy knife.

The overhanging edge of the outer wall of the attic can now be felt by means of the seeker. It is best removed by gentle taps of the chisel or small gouge. Especial care must be taken not to drive the gouge too far inwards. If this be done inadvertently, the transverse portion of the facial nerve pa.s.sing along the inner wall of the tympanic cavity may be injured. As a safeguard some surgeons use an attic punch-forceps or a burr, others a Stacke's protector which should be inserted into the attic before chiselling away its outer wall.

After the outer attic wall has been removed, the roof of the auditory ca.n.a.l and the attic should be continuous. This is verified by inserting the seeker, with its point turned upwards, within the attic, and then withdrawing it; no ridge of bone should now prevent its withdrawal.

[Ill.u.s.tration: FIG. 224. PFAU'S CURETTE FOR THE EUSTACHIAN TUBE.]

Granulations or the epithelial lining of cholesteatomata should be removed from the recesses of the tympanic cavity with a small curette.

Care must be taken not to injure the surface of the promontory, or the region of the fenestra ovalis and fenestra rotunda. It is especially important to curette away the mucous membrane from the orifice of the Eustachian tube in order that scar tissue may obliterate its lumen and so prevent reinfection of the middle ear from the naso-pharynx. For this purpose a narrow curette is necessary (Fig. 224).

Removal of the innermost portion of the floor of the auditory ca.n.a.l is not always necessary. Sometimes, however, the 'hypotympanum' is well marked, and in order to ensure a good result it is wiser to remove this projecting piece of bone. If the ridge of bone be removed piecemeal, and if the gouge or chisel be kept parallel to the floor of the ca.n.a.l, there should be no danger of wounding the bulb of the jugular vein. Cases, however, have been recorded in which this has occurred.

The final step is to see that no pockets nor overhanging ledges or ridges of bone remain, and that all the diseased area has been removed.

The cavity, although irregular in outline, should be a continuous one with a smooth surface (Fig. 225).

=Wolf's operation.= This slight modification of the Kuster-Bergmann operation requires merely a note of description. The position of the patient and the preliminary steps of the operation are the same as in the former operation.

In this operation, instead of first exposing the antrum cavity and afterwards removing the posterior wall of the external meatus, this procedure is performed in one step.

The chisel or gouge is first brought into contact with the bone just behind the upper posterior margin of the auditory ca.n.a.l. The bone is removed in layers by chiselling it away in a forward direction and in such a manner that each stroke of the chisel is carried directly into the auditory ca.n.a.l (Fig. 226). With each successive stroke, begun a little more posterior and inferior to the one preceding it, more bone is removed until at length the antrum is exposed. There should be no risk of injuring the external semicircular ca.n.a.l nor the facial nerve, owing to the fact that the outer wall of the antrum lies superficial to the tympanic cavity and aditus.

[Ill.u.s.tration: FIG. 225. THE 'RADICAL' MASTOID OPERATION COMPLETED. A, Attic and antrum; B, External semicircular ca.n.a.l; C, Promontory and inner wall of tympanic cavity; D, Remains of posterior wall of auditory ca.n.a.l; E, Facial nerve ca.n.a.l; F, Floor of auditory ca.n.a.l.]