This may be partially accounted for by the fact that although, theoretically, the application of skin grafts is easy, yet, practically, the technique is difficult. Those who favour skin-grafting point to the fact that healing of the wound may take place within five weeks, whereas, if grafting be not undertaken, cicatrization of the cavity, even under favourable conditions, can hardly be expected to occur before eight to twelve weeks.

The skin-grafting operation as suggested by Charles Ballance is generally performed as a second stage, some ten or more days after the primary operation. This, from the patient's point of view, is a serious matter; and the disappointment caused by the grafting not being always successful has induced many to give it up and to be content with what seems to be a more certain, though more prolonged, after-treatment.

More recently, however, it has been shown that in suitable cases skin grafts, if applied at the time of the completion of the primary operation, will take just as well as at a later date. This altogether alters the aspect of the case. If at the end of the primary operation it be certain that all the diseased bone has been removed and the cavity has been rendered aseptic, there can be no objection to the immediate application of skin grafts. If the result be successful, the period of after-treatment is considerably curtailed. If, on the other hand, it be not successful, the patient, beyond having a raw surface on his arm or leg for a few days, is no worse off than if the graft had not been applied.

Skin-grafting, however, cannot be done in every case. Two conditions are necessary for its success: firstly, that all the diseased bone has been removed; and secondly, that the wound cavity is aseptic.

Immediate skin-grafting, therefore, should not be employed if, in addition to the chronic disease, there be acute inflammation of the mastoid process, or of the subcutaneous tissues covering it; nor should it be done if it has been necessary to expose the dura mater over a large area, nor if there be any possibility of some subsequent intracranial complication. In such cases it may be justifiable to do skin-grafting after the acute symptoms have subsided. If, however, the case be progressing satisfactorily, the advisability of submitting the patient to a second operation should be a matter of careful consideration.

Disease of the inner wall of the tympanic cavity, or around the orifice of the Eustachian tube, is also a contra-indication against grafting, as the graft, if applied, will not take over these areas. The author's opinion with regard to skin-grafting is that, if it can be applied immediately after the completion of the primary operation (and the conditions justifying this are limited), it may be done. If, however, the conditions be such that they will not permit of this, it should not be done at all.

=Technique.= _When the grafting is done at the completion of the mastoid operation._ The first step is to see that the mastoid wound cavity is rendered thoroughly aseptic and dry. All bleeding points in the soft tissues are arrested by means of pressure forceps. The mastoid cavity is then filled with hydrogen peroxide lotion, which is afterwards syringed out with a warm saline solution, the cavity being dried with sterilized strips of gauze, and finally packed from the bottom with a fresh strip.

The size of the graft, which is usually taken from the thigh, should be at least 2 inches in width and 4 inches in length. The skin is cleansed by washing it with soap and water, then with ether, and finally with normal saline solution, the part being afterwards dried with a sterilized towel. It does not matter what type of razor is used to remove the graft, so long as it is sharp. The chief point to observe, in order to secure success, is to see that the skin is kept uniformly stretched--the tighter the better. The technique of removal of grafts is described elsewhere (see Vol. I, p. 670). The graft taken from the leg is transferred to a large spatula and smoothed out over its surface. The auricle is now pulled forward, and the gauze strip is removed from the mastoid cavity. The spatula is laid across the surface of the cavity so that it rests on the anterior margin of the wound surface (Fig. 234).

With a sharp probe the edge of the graft, which just overlaps the spatula, is held in position at this point, the spatula being gently retracted so as to leave the graft stretched across the surface of the wound cavity. With a 'stopper' (Fig. 235), the graft is now pushed inwards towards the tympanic cavity.

A gla.s.s pipette (Fig. 236), having a curved beak, is then pa.s.sed inwards beneath the graft until its point, directed downwards, lies within the tympanic cavity (Fig. 237). Any blood which has acc.u.mulated between the bone and the graft is now sucked out, and in doing this the graft becomes closely applied to the bone surface (Fig. 238). After removing the pipette, any part of the graft which is not adherent to the bone is smoothed out over its surface. The tympanic cavity and the innermost portion of the mastoid cavity are then plugged with sterilized pellets of cotton-wool wrapped in gauze and dusted with aristol powder. The outer portion of the cavity is filled up with a strip of gauze, its end being brought out through the external auditory meatus.

[Ill.u.s.tration: FIG. 234. SKIN-GRAFTING OF MASTOID WOUND CAVITY AFTER OPERATION. Skin graft being transferred from the spatula to the mastoid cavity.]

The posterior part of the graft, still projecting beyond the posterior margin of the wound, is now turned forwards so as to form a covering over the gauze filling up the wound cavity (Fig. 239). On the auricle being restored to its normal position, this portion of the graft is brought into contact with the subcutaneous tissues of the skin forming the post-aural flap, which now forms the outer wall of the mastoid cavity. The posterior incision is closed with sutures and a dry dressing and bandage are applied to the ear.

[Ill.u.s.tration: FIG. 235. BALLANCE'S 'STOPPER' FOR PUSHING IN THE GRAFT.]

_If skin-grafting be performed a week or more after the primary operation._ The post-aural wound, now healed, has to be reopened. In doing so there may be considerable bleeding, which must be arrested. The mastoid cavity is usually found to be covered with a fine layer of granulations. They are curetted away carefully, special attention being paid to the region of the Eustachian tube and the floor of the tympanic cavity. After removal of the granulations, the bone should appear uniformly smooth though somewhat vascular. If any points of carious bone be found they should be removed freely with the gouge or burr.

Considerable time may have to be spent in arresting the oozing from the surface of the bone cavity. This is best done by washing out the cavity with hydrogen peroxide solution and then plugging it tightly for a few moments with adrenalin solution. The gauze is withdrawn in a few moments. If there be still oozing, the pressure will have to be repeated until it ceases. The method of applying the graft is the same as already described.

[Ill.u.s.tration: FIG. 236. PIPETTE FOR SUCKING AIR AND FLUID FROM BENEATH THE GRAFT.]

[Ill.u.s.tration: FIG. 237. SKIN-GRAFTING OF MASTOID WOUND CAVITY AFTER OPERATION. Skin graft in the act of being sucked into position by the pipette.]

=After-treatment.= The outer dressing may be changed every second day, but the wound itself is not interfered with until the eighth day. If asepsis has been obtained, the posterior wound has usually completely healed, so that the st.i.tches can be removed at the first dressing. Owing to the secretion from within the cavity there may be a certain amount of odour, and as a rule some purulent discharge from the meatus. Under good illumination the strip of gauze is gently removed through the meatus and afterwards the small pellets of cotton-wool. In order to make certain that all are removed, a note should be made at the time of transplanting the graft as to how many were inserted in the wound cavity. The ear is now syringed out gently with a weak solution of hydrogen peroxide and afterwards dried by mopping it out with small wicks of cotton-wool.

A speculum is next inserted into the meatus and the cavity thoroughly examined. Any portions of the graft not in absolute contact with the bone or which overlap the skin of the meatus will have died, and can be removed by forceps. Care, however, must be taken not to pull off these portions too forcibly, as in doing so other pieces of the graft may be torn away. The external meatus is then plugged with a tiny piece of gauze and a dry dressing applied. If the graft has not taken and has died, it will be expelled at the first dressing on syringing.

[Ill.u.s.tration: FIG. 238. SKIN-GRAFTING OF MASTOID WOUND CAVITY AFTER OPERATION. Skin graft in position.]

[Ill.u.s.tration: FIG. 239. POSTERIOR PORTION OF SKIN GRAFT COVERING OUTER SURFACE OF WOUND CAVITY.]

Further treatment consists in syringing and afterwards drying the cavity daily. From day to day the outer layer of the graft will gradually come away piecemeal. At the end of the second week the patient can usually go home and carry out the treatment for himself, but he should be seen by the surgeon at least once a week until complete healing has taken place.

If the graft has not taken uniformly over the surface of the bone, small patches of granulations may be seen covering these areas. Under cocaine anaesthesia these patches should be curetted. If the granulations recur repeatedly, it means that there is some underlying carious bone, and that healing will not take place until the tiny fragment is eventually exfoliated.

=Results.= Statistics vary. There is no doubt that the results are better according to the experience of the surgeon with regard to grafting. If it be only applied in those cases in which it is certain that all the diseased bone has been eradicated at the primary operation, then the percentage of success with relation to failure is very high.

If, however, skin-grafting be adopted as a matter of routine, the ultimate result is probably not so good as in a similar series of cases in which grafting has not been done.

=Skin-grafting through the external meatus.= This has been advised chiefly in order to avoid a second operation.

The technique of applying the graft is practically the same as that for transplanting a large graft. The same care must be taken to get the interior of the mastoid cavity aseptic and dry. To avoid a general anaesthetic, the small grafts may be removed from the arm or leg under local anaesthesia produced by a subcutaneous injection of Schleich's solution. The graft is transferred from a small spatula to the edge of the meatus and then coaxed into position within the cavity by means of probes. The grafts are kept in position by small pellets of cotton-wool covered with gauze. If successful, the grafting may shorten the duration of the after-treatment. It is not, however, so satisfactory a procedure as applying a large graft directly through the post-aural wound.

In order to keep the grafts in position, Drew has suggested laying the graft on sterilized gold-beater's skin, and in this way applying it to the interior of the mastoid cavity.

More recently, Stoddart Barr of Glasgow has introduced an ingenious method of getting the grafts into position. The graft is manipulated over the end of a suitably-bent gla.s.s tube, having attached to the other end a piece of rubber tubing with a gla.s.s mouthpiece or small rubber bag. The graft at the end of the tube is pa.s.sed through a wide speculum to the inner wall of the tympanum, when, by blowing air through the tube, the graft is spread out over the inner surface, including the tympanic walls, aditus, and antrum.

AFTER-TREATMENT OF THE CASE

_If the posterior wound has been closed._ Provided the temperature keeps normal and there be no pain and no head symptoms, the first dressing need not take place until the fifth or sixth day. By this time the edges of the skin incision have usually united, so that the st.i.tches can be removed, although occasionally the wound may have to be opened up to permit of drainage on account of septic infection. The withdrawal of the gauze from the auditory ca.n.a.l may cause considerable pain, which, however, can be prevented by continuous irrigation of the ear before and during its removal (see p. 315).

After the gauze has been removed, the ear is mopped out with pledgets of cotton-wool. To relieve the pain a few drops of a sterilized 1% solution of cocaine may be instilled and left within the ear for a few minutes.

Under good illumination, the largest possible speculum is inserted into the meatal orifice. The cocaine solution is mopped out, and the cavity dried, in order that careful inspection of the deeper parts may be made.

The chief point is to see that the flaps are in position. There may be slight oozing from the surface of the wound, but as a rule the bone appears almost white, owing to the fact that granulations have not yet begun to form. The wound is then packed gently and evenly with gauze and the ear protected again with an external dressing and bandage.

Until the first dressing has taken place, the patient should be kept in bed. After this, provided the condition be satisfactory, he may be allowed to get up for a few hours every day, the period being gradually increased; by the tenth day or so he is practically well. In an uncomplicated case there is seldom any shock or discomfort after the operation, so that frequently the patient is anxious to be up and about even before the first dressing has been performed. It is wiser, however, to insist on rest for the first few days.

The subsequent dressings should be done every second or third day, depending on the condition found. If the wound cavity be clean, and if there be no odour, it is sufficient to irrigate it with a simple saline or boric lotion. Granulations begin to cover the bone about the tenth day, when there may be some purulent discharge necessitating daily dressings. To keep the parts sweet, an ear-bath of hydrogen peroxide (10 vols. %) may be given, the ear being subsequently irrigated with a 1 in 5,000 solution of biniodide of mercury.

Provided the patient be doing well there should be no temperature, pain, nor headaches. If any of these symptoms occur, or if the patient feels ill, or has attacks of sickness and becomes drowsy, the surgeon should at once be suspicious of some impending intracranial complication.

If the case be progressing favourably and all the diseased area of bone has been completely removed, granulations do not become exuberant, but form a fine smooth layer over the wound surface, the last portion to become covered being the region of the external semicircular ca.n.a.l and the ridge forming the remains of the posterior wall of the bony meatus.

Exuberant granulation tissue is significant of underlying bone disease.

If patches be observed, a 10% or stronger solution of cocaine should be applied to the part, which should afterwards be curetted. This process may have to be repeated on several occasions until, perhaps, a small spicule of bone is removed, after which granulations usually cease. As a rule the bone is completely covered with granulations by the fifth or sixth week. Meanwhile, owing to the growth of epithelium from the edges of the flaps, the raw surface within the wound cavity gradually becomes smaller, and with this there is diminished secretion.

The gauze packing can usually be discontinued about this period, or considerably earlier, perhaps even by the third week. In its stead an aqueous solution containing 50% of rectified spirit with 10 grains of boric acid to the ounce may be instilled into the wound cavity after it has been cleansed and dried.

Complete cicatrization of the cavity should take place within two or three months, depending on the size of the cavity.

_If the posterior wound has been left open_, the first dressing should be done on the second or third day.

The subsequent treatment depends on each individual case. If the wound has been left open on account of its septic condition, or owing to the dura mater having been exposed and found covered with granulations, its edges may be brought together by sutures after a period of ten days or so, when the wound cavity looks clean, and the packing carried out through the meatus.

On the other hand, if the wound has been left open on account of bone disease involving the inner wall of the tympanic cavity or region of the Eustachian tube, the packing should be continued through the posterior opening until the patches of carious or necrosed bone heal or are exfoliated. In these cases the granulation tissue tends to become fibrous in character in consequence of the necessary curettings, and eventually to form a thickened pad covering the inner wall.

After complete healing has taken place, the patient, before being dismissed, should be warned to visit the surgeon at least once in three months. Owing to the large cavity being lined with epithelium, desquamation takes place to a greater or lesser extent, so that the wound cavity may gradually become filled with ma.s.ses of epithelial debris or cerumen. In consequence the cavity may become septic, and on removal of the epithelial debris underlying ulceration may be found.

This can usually be cured by aseptic treatment, but if granulations have already occurred, curetting and the application of trichloracetic and chromic acid may be necessary.

DIFFICULTIES AND DANGERS OF THE OPERATION

_Anatomical difficulties._ The chief difficulties are due to a middle fossa overlapping the antral cavity, a lateral sinus projecting far forwards and lying superficially, and a sclerosed mastoid having no landmarks to indicate the way into the antrum. Unfortunately these conditions are frequently a.s.sociated.

Formerly it was advised that it was wiser not to proceed further if the antral cavity could not be discovered after chiselling to a depth of three-quarters of an inch. This advice, however, is no longer reliable, as by the combination of the Stacke, Wolf, or Kuster-Bergmann method any anatomical difficulties should certainly be overcome.

An inexperienced operator may mistake a large mastoid cell for the antrum and in this way may get into difficulties. The opening into the antrum, however, can always be identified by pa.s.sing a bent malleable silver probe in an inward and forward direction into the aditus. If only a large cell has been opened, the probe will show that it is a limited cavity.

_Haemorrhage._ In the majority of cases this is more of an inconvenience than a danger, being chiefly due to a general oozing from the soft tissues. It is, however, very necessary that the surgeon should have a clear view of the deeper parts whilst operating. If he works blindly in a pool of blood he courts disaster.

The haemorrhage is best prevented by first curetting away any granulation tissue and then packing the cavity firmly with a strip of gauze. If this be not sufficient, it may be again packed with gauze containing adrenalin solution. It will repay the surgeon to have a good a.s.sistant to keep the field of operation dry. Troublesome bleeding, coming from a small vessel in the bone, may be arrested by the local application of a small fragment of Horsley's sterilized wax (see Vol. I, p. 437).