A System of Operative Surgery Part 63

[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.

Drainage tubes should be shortened and removed as soon as possible. The gauze within the wound cavity should be changed every second day, or daily if there be much secretion. If there be much discharge and the condition be very septic, an ear-bath of hydrogen peroxide may be given at each dressing and the cavity syringed out with a weak solution of biniodide of mercury; otherwise it is sufficient to use boric acid lotion.

If the operation has been successful, the purulent discharge from the tympanic cavity rapidly diminishes, frequently ceasing before the third day. The auditory ca.n.a.l is then firmly packed with gauze, especially in its outer part, in order to prevent stenosis of its lumen, which is liable to occur if the posterior fibrous portion of the ca.n.a.l has been separated from the bony meatus during the operation. Granulations very quickly block the aditus and so separate the antrum and mastoid cavity from the tympanic cavity. The wound can now be treated as an ordinary deep surgical wound, care being taken that it is packed from the bottom at each dressing.

If all the diseased bone has been removed, smooth healthy granulations will cover the wound. The continuance of pus from any spot, or the local growth of exuberant granulations, suggest the presence of an infected cell or a fragment of carious bone. Under cocaine anaesthesia, the part should be inspected carefully, and, if necessary, curetted freely. In other cases the local application of chromic or trichloracetic acid is sufficient.

After the second week the wound becomes shallower, actual healing of the wound depending on the size of the cavity.

Unless a very large amount of bone had to be removed, the resulting deformity is not great and usually only consists of slight sinking in of the skin. In some cases the final result is only a fine scar, which can generally be concealed by the hair.

The difficulties and dangers of the operation are considered in the next chapter (see p. 412).

=Results.= 1. If the operation has been successful (and this is usually the case), pyrexia and pain rapidly disappear, the patient experiencing remarkable relief from the head symptoms, so that within twenty-four hours he feels almost well. Healing of the wound is usually complete within six weeks, and before this date the hearing power will probably have been restored to normal.

2. The operation may not have been successful and the following unfavourable symptoms may occur:--

(_a_) The pyrexia may continue irregularly for a few days. If there be no other symptoms, this is probably due to septic absorption from the wound and need not cause very great alarm. If accompanied by pain, it may either mean that all the infected mastoid cells have not been opened, or suggest the onset of osteomyelitis of the temporal bone. If, in addition, such symptoms as rigors, delirium, optic neuritis, headaches, or vomiting occur, they indicate some intracranial complication.

In cases of doubt it is wiser to explore the wound under a general anaesthetic and then to determine what operation will be necessary.

(_b_) The general condition of the patient may be excellent, but otorrha or a fistula over the mastoid process may persist. Continuance of otorrha, 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 ca.n.a.l. 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 pa.s.sed 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, pa.s.sing it from above downwards along the pa.s.sage 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.

In adults necrosis is rare excepting as a localized patch usually situated superficially in the cortex of the mastoid process. Partial necrosis of the labyrinth, more especially of the vestibule and the portions of the semicircular ca.n.a.ls, is also met with occasionally. When the necrosed area is superficial, such as the squamous portion of the temporal bone or the cortex of the mastoid process, it should be removed. If, however, it be situated more deeply, forcible removal should not be attempted until the sequestrum becomes loose, the wound cavity being meanwhile kept as aseptic as possible.

=Osteomyelitis.= In children, as the result of acute inflammation of the mastoid process, the bone may be found riddled with small points of pus, sometimes termed osteomyelitis. As a result of free opening of the mastoid cavity recovery, as a rule, takes place in the ordinary manner.

Distinct from this is another condition in which thrombosis of the diploic veins occurs. It is, fortunately, a rare complication of mastoid disease. It may occur before operation or be the result of infection of the bone as a result of operation. The infection tends to spread in every direction, more especially upwards along the parietal region and towards the occiput. With this, localized areas of necrosis or abscesses may occur, giving rise to painful swellings on the head, and usually are accompanied by cellulitis of the scalp, pyrexia, and intense headaches.

The only chance of recovery is to expose the affected area freely, and thoroughly remove all the diseased bone. To do this it may be necessary to lay bare the dura mater over a considerable area. If, however, the disease be not quickly eradicated, death will eventually occur as a result of extension of the septic infection to the larger veins, or from some other intracranial complication.