Part 63 (1/2)

[Ill.u.s.tration: FIG. 218. SCHWARTZE'S OPERATION. Showing exposure of the antrum. Note sloping position of gouge in removal of bone in region of lateral sinus.]

Anteriorly, the bone is removed as close to the posterior wall of the auditory ca.n.a.l as possible, including the suprameatal spine. Above, the line of chiselling must not extend beyond the zygomatic ridge, whilst below sufficient bone should be removed towards the tip of the mastoid process to permit of inspection of the deeper parts of the wound.

From time to time the operator makes use of the _seeker_ (Fig. 219).

This is a blunt-pointed probe whose tip is bent at right angles to its shaft. With it any opening is probed carefully to see whether it is merely a mastoid cell, or dura mater covering the outer wall of the lateral sinus, or the middle cranial fossa, or if indeed it is the antrum itself. The chief mistake is to work too low down. If the antrum be small it may be missed, and the bone may be chiselled away too deeply in endeavouring to discover it and the facial nerve or the external semicircular ca.n.a.l injured. It is wiser, therefore, to work high even if the dura mater of the middle fossa is exposed by doing so.

This should not lead to any harmful result provided the dura mater is not injured.

As soon as the antrum is reached, pus will be seen to ooze through the opening made, especially if it is under tension. The probe or seeker can now be pa.s.sed into a cavity of varying size. The antrum is recognized by its smooth surface, which has quite a different appearance to that of the mastoid cells.

[Ill.u.s.tration: FIG. 219. SCHWARTZE'S SEEKER.]

(_b_) _If the mastoid be not sclerosed._ The pathological condition found on removal of the superficial cortical layer depends on the anatomical structure and on the extent and virulence of the inflammatory process. Only a few cells may be involved, or on the other hand the whole mastoid process, if it be of the pneumatic type, may be converted into a mere sh.e.l.l of bone, forming a large cavity filled with ma.s.ses of septic granulation tissue, carious bone, and pus. Sometimes, indeed, owing to the tegmen tympani or bony wall of the sigmoid sinus being already destroyed, the dura mater above or the lateral sinus posteriorly may be found already exposed within the cavity. If this is the case the pus may pulsate if present in large quant.i.ty. Any patches of soft carious bone or granulation tissue should be removed with the curette.

If the disease be limited to a few superficial mastoid cells, it is sufficient, according to those who do not always explore the antrum, to expose and curette the cavity freely and to do nothing further. This, however, should only be done if the bone surrounding the abscess cavity is hard and apparently normal, and if there is no tract of granulations leading from it in any direction. If an opening be found leading directly into the antrum, it should be enlarged with the curette or gouge. The extent of the antrum is next defined with the seeker, any overlapping ledges of bone being removed by the gouge until the whole of its inner surface is exposed.

The region of the aditus is now inspected under good illumination, using a head-light if necessary. It is recognized as a small opening at the anterior inner part of the antrum, on the floor of which may be seen the posterior border of the external semicircular ca.n.a.l, standing out as a whitish rounded eminence. Bone may be removed from its upper inner margins, but the lower portion should not be interfered with for fear of injuring or displacing the incus. To confirm the opening into the aditus, a blunt-pointed curved probe may be pa.s.sed for a short distance through the aditus into the attic (Fig. 220).

With the curette all granulations should be removed.

_Treatment of the mastoid process._ The question now arises as to how much bone to remove. This depends on the condition found; the chief point is to make certain of removing all the infected cells.

In the case of marked sclerosis, the opening need not be large because, if the bone between the cortex and the antrum be solid, it is hardly probable that infection can spread through it to any outlying cells in the tip of the mastoid or elsewhere.

[Ill.u.s.tration: FIG. 220. SCHWARTZE'S OPERATION COMPLETED. The seeker is being pa.s.sed through the aditus into the attic. Note the posterior border of the external semicircular ca.n.a.l which forms the inner and lower margin of the aditus.]

In the diploic and pneumatic varieties, the seeker must be used constantly in order to discover any outlying cells, which are then opened freely. If this be done systematically, infected cells may be found some distance away from the antrum itself, although an area of apparently healthy bone lies between them and the antrum. It must not be forgotten that cells may extend posteriorly as far as the occipital bone, or anteriorly along the zygomatic process, or even into the upper posterior part of the auditory ca.n.a.l itself (see p. 374). If such infected cells be not discovered, healing will be prevented.

However small or large the opening may be, all rough corners must be removed, so that at the end of the operation a smooth funnel-shaped cavity exists. To obtain this _a burr_ may be used, worked either by the electric motor or, if a portable one, by an a.s.sistant. The burrs are of various sizes and of the cross-cut variety recommended by Ballance. Some operators perform the operation by burring throughout. Personally, during the earlier stages of the operation, I prefer to use the gouge and mallet. If the operator has not had much experience in the use of the burr there is always a slight risk, if it be not kept sufficiently under control, and especially if too great pressure be used, of it being driven through the dura mater above or into the lateral sinus posteriorly, or of it injuring the contents of the tympanic cavity. As a means of finis.h.i.+ng the operation no instrument could be better. In private practice, however, few surgeons keep one. For this reason it is advisable to become accustomed to the chisel and gouge.

_Removal of part of the posterior wall of the auditory ca.n.a.l._ This may be necessary if the anterior wall of the antrum and mastoid process be affected. The fibrous portion of the auditory ca.n.a.l is partially separated from the bony portion and held forward by means of a retractor. The upper posterior portion of the bony meatus can now be removed either by means of punch-forceps or by the chisel, to what extent does not matter so long as its innermost portion, 'the bridge,'

is not interfered with, that is, so long as the tympanic cavity and aditus are not encroached upon.

_Exposure of the dura mater and lateral sinus._ This may have already occurred before the operation, as a result of extension of the bone disease, or it may be necessary to do so during the course of the operation. Owing to the fact that an extra-dural abscess is a frequent complication of acute inflammation of the mastoid process, Victor Horsley and Korner advocate the exposure of the dura mater and the lateral sinus in every case, especially if a tract of carious bone leads in their direction. No harm is done in exposing these structures, and it precludes missing an extra-dural abscess.

It is better to expose the dura mater than to leave it covered with infected bone and septic granulations.

_Final step of the operation._ In order to make certain that a free opening exists between the antrum and the tympanic cavity, some warm boric lotion should be syringed through the opening of the aditus. A small syringe is used, having a fine piece of india-rubber tubing fixed on to its point. The end of the tubing is pushed into the entrance of the aditus. The fluid is then syringed through and should emerge from the external meatus. This is also beneficial in order to cleanse the tympanic cavity of its purulent secretion. To expel all the fluid from the middle ear the syringe is emptied and the piston withdrawn to its full extent. Its point is again placed within the entrance of the aditus and the piston pressed home, so that air is forced through and so drives out any remaining fluid from the tympanic cavity into the external meatus, which in its turn should be carefully dried. If there be no perforation, or if it be very small, the membrane should be freely incised before fluid is syringed through the aditus.

_Immediate treatment of the wound cavity._ The wound cavity is lightly packed with sterilized ribbon gauze, half an inch in width. Care must be taken to introduce the gauze right down to the aditus and to pack the cavity evenly.

The wound should be left open for a few days until the acute inflammation of the soft tissues has subsided, after which the upper and lower angles of the wound can be partially closed by sutures. A strip of gauze is also inserted into the auditory ca.n.a.l and a light dressing of plain sterilized gauze and a pad of cotton-wool covers the ear and surrounding parts. The bandage should be pa.s.sed round the head and not beneath the chin, as the latter method is often a source of great discomfort to the patient during the stage of vomiting following the anaesthetic.

Blake of America has suggested that the wound should be allowed to fill with blood-clot on the supposition that the subsequent organization of the clot will result in a rapid closure of the wound. This method cannot be considered seriously owing to the impossibility of keeping the wound sterile.

=After-treatment.= There is seldom any shock, but there may be considerable pain during the next twenty-four hours.

If there has been no subperiosteal abscess, the dressing need not be removed for forty-eight hours. If an abscess has been present the dry dressing should be removed after twenty-four hours, and if there is much dema and inflammation of the surrounding region, a compress of wet boric lint, kept in position by a few turns of a bandage, should be subst.i.tuted, and changed every four hours.