Tympanoplasty-Outer Surface Grafting Technique

Published on 13/06/2015 by admin

Filed under Surgery

Last modified 22/04/2025

Print this page

This article have been viewed 2481 times

Chapter 9 Tympanoplasty—Outer Surface Grafting Technique

Jose N. Fayad, James L. Sheehy

Videos corresponding to this chapter are available online at www.expertconsult.com.

The aims of tympanoplasty are elimination of disease and restoration of function. Restoration of function requires a tympanic membrane; an air-containing, mucosal-lined middle ear (so that the membrane vibrates); and a secure connection between the tympanic membrane and the inner ear fluids. This chapter presents one of the three major techniques of tympanic membrane grafting: the outer surface, or onlay, procedure. This technique is used with rare exceptions by physicians of the House Clinic. Before describing the surgical procedure, the evolution of tympanic membrane grafting techniques, patient selection, and evaluation and counseling before surgery are discussed.

HISTORICAL ASPECTS

Systematic reconstruction of the tympanic membrane, the sine qua non of the modern era of reconstructive ear surgery, had its beginning with reports by Wullstein ¹ and Zollner.² Split-thickness or full-thickness skin was placed over the de-epithelialized tympanic membrane remnant. The initial results were very encouraging, but graft eczema, inflammation, and perforation were common.

As a result of these experiences, most surgeons had begun changing to undersurface (underlay) connective tissue grafts by the late 1950s (see Chapters 11 and 12). The House Clinic physicians continued using an onlay technique, but changed to “canal skin,”^3,⁴ which actually was periosteum graft covered by canal skin. This change was made in 1958, and resulted in an immediate improvement in results. Draining ears and total perforations continued to have a failure rate reaching 40%.

In 1961, Storrs ⁵ published the results of a small series of cases in which temporalis fascia had been used as an outer surface graft. Changing to this technique resulted in a dramatic improvement in results over the next 3 years: greater than 90% graft take.⁶^–⁸

PATIENT SELECTION AND EVALUATION

A patient with chronic otitis media may consult a physician because of a hearing impairment or because of discharge from the ear. Occasionally, the patient may have symptoms of more advanced chronic ear pathology, such as pain, vertigo, or facial nerve paralysis. Careful evaluation of the symptoms and findings allows the otologist to determine the need for surgery, its urgency, and the anticipated result. Only by completing the evaluation can the patient be advised properly. A good surgical result should not be a disappointment to the patient if there is proper counseling.

Let us assume, for purposes of this chapter, that the patient has a dry central perforation. The ear may drain briefly with upper respiratory infections or if water is allowed to get into the ear. This discharge responds promptly to local medication. The preoperative treatment of the draining ear is discussed in depth in Chapter 16. When one is dealing with a dry central perforation, or inactive disease, surgery is elective, and the patient (or family) should be so informed. Assuming that the problem is unilateral, with only a mild hearing impairment, the only indication for surgery is to avoid further episodes of otorrhea.

In children, it is best (from a psychological standpoint) to avoid elective surgery of any type between the ages of 4 and 7 years. In ear surgery, it is wise to wait until after age 7 so as not to lay the groundwork for serous otitis media. If the problem is bilateral, there is a hearing problem, and the ears do not drain often, fitting with hearing aids in each ear may be preferable for children younger than 8 years; however, the parents have to make the decision. At age 8 and thereafter, the patient (and child) should be allowed to make the decision.

When contemplating tympanoplasty, the House Clinic physicians do not usually test to determine the status of the eustachian tube.⁹ The philosophy has been that tubal malfunction per se is not a contraindication to tympanoplasty, but that the operation would not be successful unless tubal function is re-established. Many patients showing no tubal function by various available tests used in the past have been operated on to eliminate a chronic drainage problem. When the ear heals, the drum is usually mobile. Re-exploration in some of these patients has shown normal mucosa in the tubotympanum, where before surgery the mucosa was of a very poor quality. It would seem that the surgery, in eliminating infection and sealing the ear, is in itself the best treatment for the obstructed tube.

PATIENT COUNSELING

What is the outlook with surgery, and what are the risks and complications? A surgeon must relate his or her own experience. House Clinic physicians explain that the likelihood of obtaining a permanently healed, dry ear, which may be treated normally, is better than 90%. “The only complication that happens with any degree of regularity, and is serious, is a total loss of hearing in the operated ear. That likelihood is no more than 1%. All of the other things listed here are either very remote or are temporary.” (“Listed here” refers to the Risk and Complications section of a patient Discussion Booklet. The Risk and Complications Sheet is given to the patient at the time the surgery is scheduled, which allows the patient to review the sheet leisurely. Appendix 1 is the Risk and Complications Sheet.)

PREOPERATIVE PREPARATION

If the patient is a child, the preoperative visit occurs the day before surgery. Surgery is done under general anesthesia the following morning. The child is released to the parents’ care in the afternoon.

For adults, the preoperative visit is sometimes the morning of surgery. The patient goes to the hospital for afternoon surgery, which is done under local or general anesthesia. The patient may be kept in the hospital overnight, depending on many circumstances.

PREPARATION IN THE OPERATING ROOM

The smoothness with which the operation proceeds depends not only on the ability of the surgeon, but also on the organization of the team (anesthesiologist and surgical nurse) and arrangements in the operating room. The patient’s hair is shaved 3 cm above and behind the ear. The skin is cleansed with an iodine-based soap and rinsed with water. A sterile plastic adhesive drape is placed after applying tincture of benzoin. The mattress of the operating table is taped securely to the table to prevent it from slipping when the table is tipped from side to side or into the Trendelenburg position. The patient is placed on the table with his or her head at the foot of the table, which allows the circulating nurse or anesthesiologist free access to the table controls, which are at the feet of the patient. The patient’s head and shoulders should be as near to the surgeon’s side of the table as possible. A pillow is placed under the patient’s knees. The Bovie plate goes under the patient’s buttocks.

Anesthesia

Ear surgery can be performed with the patient under local anesthesia in many cases. The decision depends on the age of the patient and other factors. Lidocaine with 1:100,000 epinephrine is used for postauricular and meatal incisions. Some of the injection material should find its way under the skin of the posterior superior wall of the canal (the vascular strip) and into the middle ear. General anesthesia is used in children, in most mastoid surgery, and in procedures that require more than 1.5 hours of operating time. The anesthesiologist should be at the feet of the patient (which is actually the head of the table) to allow the surgeon and scrub nurse complete freedom at the patient’s head.

A few useful suggestions for the anesthesiologist are as follows:

1. Have extra-long tubing for the gas machine to allow seating at the foot of the patient.

2. Start the intravenous infusion in the forearm, and extend the tubing to the foot of the table.

3. Place the blood pressure cuff on the arm opposite the ear to be operated on.

4. Be certain that the patient is secured to the table with wide adhesive tape. The eyes should be taped shut.

Arrangement and Instrumentation

Particular attention should be paid to operating room arrangement (Fig. 9-1). The anesthesiologist is at the patient’s feet, far removed from the operating field, and the scrub nurse is directly across from the surgeon, where the nurse may be of the most assistance. The same arrangement, minus the anesthesiologist, is used for procedures done with the patient under local anesthesia.

FIGURE 9-1

It is important for the comfort of the surgeon that the patient is in a satisfactory position. The table is usually placed in a few degrees of Trendelenburg position and rolled slightly toward the surgeon. The patient’s head is adjusted as necessary, usually flexed slightly onto the opposite shoulder. The surgeon should be comfortably seated on a chair with a back support. The surgeon should use the back support and be in a comfortable position so that all back and arm muscles are relaxed.

SURGICAL TECHNIQUE

The lateral surface grafting technique involves eight steps: (1) transmeatal canal incisions, and elevations of the vascular strip; (2) postauricular exposure, and removal and dehydration of the temporalis fascia; (3) removal of canal skin; (4) enlargement of the ear canal by removal of the anterior (and inferior) canal bulge; (5) de-epithelialization of the tympanic membrane remnant; (6) placement of the rehydrated fascia on the outer surface of the remnant, but under the manubrium; (7) replacement of canal skin; and (8) closure of the postauricular incision and replacement of the vascular strip transmeatally.¹⁰

Transmeatal Incisions

Incisions are made along the tympanomastoid and tympanosquamous suture lines, demarcating the vascular strip with a No. 1 (sickle) knife (Fig. 9-2). The vascular strip is the area of the canal skin that covers the superior and posterior portions of the ear canal between these two suture lines. It is easily demarcated from the skin of the remainder of the ear canal because of its thickness, and the fact that it balloons up when local anesthesia is injected into the area. The vascular strip is elevated from the bone, from within outward using a round knife (Fig. 9-3).

A semilunar incision is made in the outer third of the ear canal, using a Beaver knife with a No. 64 blade, connecting the two incisions already made along the border of the vascular strip (Fig. 9-4). The knife blade is angled toward the bone to thin the 1 or 2 mm section of the membranous canal included.

Postauricular Exposure and Removal of Fascia

The skin incision must provide adequate exposure for the operative field. It should extend far enough forward superiorly and inferiorly to allow adequate exposure of the bony meatus when the ear is retracted forward. Failure to do this may result in difficulty seeing structures in the posterior part of the middle ear. The superior portion of the incision begins at the most anterior extent of, and 1 cm above, the postauricular fold. It is continued into the postauricular fold at the level of the lower border of the muscle and extends inferiorly under the lobule of the ear.

Exposure of the temporalis fascia is facilitated if ample local anesthetic has been injected to balloon the area. A retractor is inserted to retract the skin margins in this area and to obtain hemostasis. By lifting up on the retractor, one may pull the areolar tissue away from the fascia, facilitating the dissection and ensuring that all loose areolar tissue is lifted off the fascia before the fascia’s removal.

Local anesthesia is injected under the fascia to elevate it slightly from the underlying muscle. A 2 × 2 cm piece of fascia is removed. The fascia is spread on a polytef (Teflon) block, undersurface upward, and any adherent muscle is removed. The fascia is placed on a fascia press, absorbable gelatin sponge (Gelfoam) is placed on the fascia, and the press is closed. The press is opened after 5 minutes, and the Gelfoam is removed; the fascia, now smooth and partially dehydrated, is left attached to the press. The press, with the attached fascia, is placed under an electric lamp to complete the dehydration process.

An incision is made through the soft tissue above the meatus, from the root of the zygoma, horizontally, along the linea temporalis. This horizontal incision is extended posteriorly to the level of the skin incision. The incision is extended inferiorly, below the linea temporalis, following the postauricular incision, incising the periosteum until the incision curves forward, down to the level of the floor of the ear canal. The periosteum is elevated superiorly (under the temporalis muscle), posteriorly and anteriorly, using a Lempert elevator, to obtain adequate exposure of the mastoid cortex. A self-retaining retractor is inserted to retract the auricle and vascular strip forward, exposing the ear canal.

Removal of the Canal Skin

The periosteum and canal skin are elevated from the bone as far as the annular ligament (Fig. 9-5). Care should be taken not to elevate the ligament and the remnant of the middle fibrous layer. The dissection is superficial to the fibrous layer of the remnant in such a way that the remnant is de-epithelialized in continuity with the canal skin, if possible. It is often easier to begin the final removal and de-epithelialization by starting anterosuperiorly, using a cup forceps (Fig. 9-6). Removal of the canal skin and de-epithelialization are continued inferiorly and posteriorly. The periosteum and canal skin are removed from the ear and kept moist in Tis-U-Sol irrigating solution.

FIGURE 9-5

In elevating the periosteum and the canal skin, one works perpendicular to the annular ligament and remnant, keeping the instrument on the bone at all times, until the dissection is completed to the level of the remnant. The dissection is continued parallel to the annular ligament to avoid elevating it and the remnant (Fig. 9-7).

Enlargement of the Ear Canal

Through the use of a drill and continuous suction-irrigation, the ear canal is enlarged by removal of the anterior and inferior canal bulges (Fig. 9-8). The importance of this step in the lateral surface grafting technique cannot be overemphasized. Removal of this bone enlarges the field of surgery. The anterior and inferior sulci are thoroughly exposed to allow de-epithelialization and satisfactory graft placement. The acute angle that exists anteriorly is opened, helping to prevent postoperative blunting. There is no area hidden from postoperative observation. Enlarging the ear canal is routine in all lateral surface grafting procedures, and is the main reason for removal of canal skin.

De-epithelialization of the Tympanic Membrane Remnant

The lateral surface grafting technique demands a complete de-epithelialization of the remnant. Although the graft may take without all the skin having been removed, postoperative epithelial cysts may develop. Attention is directed first to the ear canal bone immediately adjacent to the bony annulus. Particular attention is paid to the anteroinferior bone 1 mm lateral to the annulus, where a small vessel and nerve perforate the bone, and where there is a particularly tight attachment to the skin. Next, the tympanic membrane remnant is checked carefully for skin. If there is a question about whether de-epithelialization has been thorough, a portion of the remnant is removed to be certain. The size of the perforation is of no consequence in regard to graft take in the lateral surface technique.

Preparation of Packing

The surgical nurse should have begun preparing Gelfoam packing before or shortly after the beginning of the operation. Uncompressed Gelfoam is cut into an ample number of various-sized pieces and soaked in antibiotic-cortisone solution. Pieces of Gelfoam are removed from the solution and compressed (on a tongue blade or a paper Gelfoam packet) until most of the solution has been removed. The Gelfoam is put aside and allowed to dry more until needed by the surgeon.

Placement of Fascia

When the perforation is large, or the fascia is unusually thin, it is helpful to fill the middle ear with Gelfoam packing before placing the graft. The Gelfoam serves as an artificial remnant and facilitates graft placement. The fascia is placed under the malleus handle. When the manubrium is surrounded by remnant (small perforation), the remnant is separated from the malleus handle to allow proper placement of the fascia.

The dehydrated fascia is trimmed to an oval shape measuring approximately 1.3 × 1.5 cm. A slit is cut in the fascia to allow placement under the manubrium (Fig. 9-9). The two cut ends are grasped with the forceps, and the fascia is immersed for a few seconds in Tis-U-Sol irrigating solution to hydrate it.

The fascia is placed over the perforation and immediately slipped under the manubrium (Fig. 9-10). One ensures that the apex of the slit in the fascia comes into contact with the tensor tendon. The fascia is adjusted to the remnant anteriorly and inferiorly, with care being taken that it does not extend onto the bony wall anteriorly, unless there is no remnant at all, then it should extend only for 1 mm at the most. The anterior flap is turned back over the exposed manubrium, resulting in a better appearance of the membrane when healed (Fig. 9-11).

When the malleus is absent, and there is only a small remnant present, it is necessary to insert the fascia in a different way to result in the stabilized graft (Fig. 9-12). The fascia is cut twice, creating a flap that can be tucked under the lateral wall of the epitympanum. The anterosuperior edge of the fascia is swung posteriorly to overlap the upper edge of the graft and secure the seal of the middle ear (Fig. 9-13).

Replacement of Canal Skin

The canal skin is replaced to cover the bone from which it was removed. It is positioned only slightly more medially, allowing it to overlap the fascia by 1 mm (Fig. 9-14), which helps promote rapid epithelialization. Epithelialization is particularly important in preventing blunting in the anterosuperior sulcus. There must be no edges of epithelium turned under, or small epithelial cysts may develop on the surface of the fascia during healing.

FIGURE 9-14

The first piece of packing is a small, dry, rolled-up (cigar-shaped), tightly compressed piece of absorbable Gelfoam, which is placed in the sulcus anteriorly. The canal is packed tightly with pledgets of slightly moist Gelfoam, leaving room posterosuperiorly for the vascular strip.

Closure and Replacement of the Vascular Strip

The retractors are released, and the vascular strip is pushed anteriorly to lie over the packing. One suture is placed subcutaneously postauricularly to stabilize the auricle. Transmeatally, the vascular strip is replaced in the ear canal in the exact position from which it came (Fig. 9-15). Gelfoam packing in the canal is completed, and a plug of cotton is placed in the outer meatus. The postauricular incision is closed with subcutaneous sutures, and a mastoid dressing is applied.

POSTOPERATIVE CARE

The mastoid dressing is removed the day after surgery. The patient is given a postoperative instruction card (Appendix 2) just before entering the hospital. It is important to review some aspects of this information with the patient. The patient should be reminded not to blow the nose and not to get water in the ear. An antibiotic is prescribed and should be taken as directed on the prescription label. There will be discomfort for a few days, and the patient should take aspirin or acetaminophen four times a day regularly for the first few days to keep the pain under control. Nothing need be done with the cotton in the ear, but it may be changed if it becomes soiled.

The patient is asked to touch the edge of the auricle; the physician points out that the ear is numb, and that it is going to take a few months for the numbness to fade. There is also tenderness on the incision behind the ear. This tenderness diminishes rapidly, but it may be 6 months before it is totally gone. Finally, the patient should be reminded of the first postoperative appointment, which should be scheduled 7 to 10 days later in the physician’s office.

At the first postoperative visit, the cotton plug in the ear canal is removed, and the ear is inspected. The Gelfoam should appear firm. A piece of Gelfoam should be removed to show to the patient so that the patient understands that it will eventually turn to a liquid and will run out of the ear. The patient is instructed to begin using ear drops (of one type or another) 3 weeks after the date of surgery, twice daily. The drops may be started sooner if the ear begins to drain, an indication of liquefaction of the Gelfoam. The second postoperative visit is scheduled for 6 to 8 weeks after the date of surgery. At this point, 80% to 90% of the ear should be totally healed.

PROS AND CONS OF OUTER SURFACE TECHNIQUE

One of the problems faced by a novice surgeon is that there are many techniques and prostheses recommended as “the best—always works well.” How well a technique or prosthesis works for the individual depends on the technical ability of that individual—his or her judgment and manual dexterity.¹¹ The outer surface grafting technique has numerous advantages and disadvantages. The advantages are well known to all who have used the technique. First, the exposure is excellent—one can see everything necessary without moving the microscope. Second, one may remove as much remnant as necessary to eliminate the disease. There is no need to scrape in many different places. Third, the graft rate take is high. Fourth, it is one technique that can be used in all cases.

There are disadvantages that may outweigh the advantages for some individuals. First, the technique requires very precise surgery to avoid problems. Second, the healing time is longer than with the undersurface technique. Third, if the operation is not done extremely skillfully, the patient may develop either blunting in the anterior sulcus or lateral healing, both of which may result in a healed ear with worse hearing.

Healing Problems

One of the disadvantages of the outer surface grafting technique, as already noted, is that although there is a very high graft take rate regardless of how the operation is performed, there are healing problems. These healing problems may outweigh the advantages for some individuals.¹⁰ These healing problems became evident soon after the technique was started in the early 1960s: lateralization of the graft, blunting in the anterior sulcus, excessive membrane thickness, epithelial cysts between the remnant and the fascia, and epithelial pearls on the drum surface and ear canal. Most of these have ceased to be major problems, but they still occur in a small percentage of cases.

Lateralization of the Tympanic Membrane

The very first problem that was noticed with this technique was lateralization of the membrane (Fig. 9-16). This lateralization usually did not become apparent until 6 to 12 months after surgery, and resulted from the fascia not being placed under the malleus handle when the technique was first introduced (see Fig. 9-10). When lateralization has occurred, the patient’s hearing is reduced, but often not as much as anticipated. The appearance is of an eardrum smaller than normal-sized, mobile, and at a direct right angle to the line of vision. Treatment of this problem (if needed) requires reoperation and the placement of the new graft underneath the malleus handle.