18 Tympanoplasty

Reconstruction of the Tympanic Membrane

Type I Tympanoplasty

Approach. Endaural or postauricular (Chapter 17). The graft is harvested, and the plane of the tympanic membrane is adequately exposed with self-retaining retractors. If necessary, the entrance to the ear canal can be enlarged with a burr.

Recipient bed. The margins of the perforation are freshened by cutting around them with a sickle knife held at an oblique angle to the tympanic membrane. A microforceps grips the resected tissue with the margins under tension (Fig. 18.1a, b). This step is always completed before the tympanic annulus is separated from the sulcus.

Tympanomeatal flap. The tympanomeatal flap is outlined with a straight round knife. Cuts are made at the 11 and 5 o’clock positions in the right ear and at 1 and 7 o’clock in the left ear (see Fig 17.3 and Fig. 18.2; see also Chapter 17). The meatal flap is elevated toward the tympanic membrane from the bone with an angled round incision knife, aided by a suction tip (Fig. 18.3).

Opening the middle ear cavity. The middle ear cavity is opened in the posterosuperior quadrant, where the annulus is easier to detach from the sulcus. As the tympanomeatal flap is raised, the thin mucoperiosteum becomes tense and can be divided without damaging the chorda tympani. The annulus fibrosus is dissected from the sulcus below the attachment of the chorda tympani, using first a sickle knife and then a round incision knife. The mobilized tympanomeatal flap is reflected forward (Fig. 18.4).

Evaluation of the ossicular chain. The bony posterolateral attic wall (area that can be under-run with a round knife) is taken down with the House curette—after first thinning it with a diamond burr if necessary—until the long process of the incus, the stapes, and the tympanic facial nerve segment can be identified (Fig. 18.5). At this point the manubrium of the malleus is probed very gently with a needle to assess the continuity and mobility of the ossicular chain.

Graft selection. The graft (fascia, perichondrium, or cartilage) is sized so that it will safely overlap the perforation on all sides and extend slightly onto the posterior canal wall (to allow for shrinkage; see Chapter 17).

Graft placement. The graft is introduced into the middle ear cavity with a needle and suction tip, allowing approximately 3 mm of overlap between the graft and perforation margins. The graft may be placed medial to the manubrium and is held in place by adhesion (underlay technique, Fig. 18.6). Later the posterior portion of the graft will be below the tympanomeatal flap and will slightly overlap the bony posterior wall of the ear canal.

Returning the flap. The tympanomeatal flap is returned to its original position with meticulous reapproximation of the flap margins. Rounded silastic strips (Fig. 18.7) are placed into the ear canal to cover the junction of the replaced meatoplasty and tympanomeatal flap while also supporting the graft from the lateral side (Fig. 18.8).

Wound closure. The ear canal is packed with antibiotic-impregnated gelatin sponge and short, superficial strips. The wound is closed in layers.

Postoperative Care

Perioperative antibiotics.

Patients with postoperative infection or poor wound healing should receive broad-spectrum antibiotics until culture results are known.

Packing is left in place for 3 weeks.

Valsalva maneuvers are started on the first postoperative day.

See Chapter 14 for details.

Alternatives

Closure Technique

Modified underlay technique. With a lack of residual anterior membrane, the graft can be delivered to the repair site using a pull-through technique. The anterior annulus is undermined to the bone at one or two points with a sickle knife, and one end of the graft is pulled through the tunnel to the plane of the tym-panic membrane with a tiny hook or suction tip (Fig. 18.9). If an adequate margin is present, the same technique can be used on the anterior pars tensa without undermining the annulus.

Onlay technique. The epithelium is elevated from the tym-panic membrane surface along with the manubrium and returned after the graft has been placed on the tunica propria. The margins of the perforation are freshened, and the tympanomeatal flap is dissected with an angled round knife over the firmly adherent posteroinferior annulus onto the tunica propria. In this way the tympanic membrane epidermis can be developed anteriorly in continuity with the tympanomeatal flap. It is dissected from the manubrium and short process with a sickle knife.

There is a risk that a flap cholesteatoma may form as a result of residual squamous epithelium, and blunting of the tympanomeatal angle may occur. Advantages are a more stable anterior graft placement and a normal volume of the middle ear cavity.

Myringoplasty. Special type of type I tympanoplasty: The tympanic membrane is closed with an underlay technique without evaluating the ossicular chain and without mobilizing the posterior annulus (prerequisites are a healthy tympanic membrane and middle ear and no conductive impairment). Generally this procedure involves an endaural approach with an autologous graft, freshening the perforation with a sickle knife, and removing the rim of loose epithelium with a cup forceps. A small fascial graft is introduced through the perforation and approximated to the medial surface of the tympanic membrane with a needle and suction tip.

Reperforations. Small reperforations: With a dry middle ear, the margins of the perforation are freshened with a sickle knife and the epithelial rim is removed. A pressed, postauricular fat-connective tissue graft is passed through the perforation with a needle, approximated with a microsuction tip, and covered laterally with silastic film.

Larger reperforations require a repeat tympanoplasty, which is done after sequelae and swelling from the initial procedure have subsided.

Graft Materials

Perichondrium. This material is best suited for small to medium-sized tympanic membrane defects that are susceptible to infection. It is similar to fascia in its workability and handling.

Cartilage. Cartilage is preferred for reconstructing subtotal defects, closing defects associated with poor ventilation or retraction pockets, recurrent perforations, and infection-prone ears.

The palisade technique is particularly useful for very anterior defects without adequate margins, impaired eustachian tube ventilation, and adhesive processes.

Cartilage–perichondrium composite grafts with a cartilage disk are excellent for reconstructing subtotal defects or old welding spatter injuries. The central cartilage disk (see Chapter 17, p. 365) is placed with its perichondrial side against the tym-panic membrane. It can also be incised for easier application, or a portion may be excised to accommodate the (de-epithelial ized) manubrium (“under-overlay” technique). A pure cartilage disk graft is worked and used in much the same way.

Palisades. Approximately six precut cartilage struts (see Chapter 17, p. 365) are wedged into place beneath the tym-panic membrane from one side of the perforation to the other, all directed parallel to the manubrium. They are shortened according to their position so that their intrinsic tension creates a slight bow (Fig. 18.10a, b). The struts are covered laterally with perichondrium or fascia.

Ossicular Chain Reconstruction

Lenticular Process Defect (Type II Tympanoplasty)

Incus Defect or Loss (Type IIIA Tympanoplasty)

The defect is bridged with a partial ossicular chain replacement prosthesis (PORP) (stapes elevation) consisting of autologous ossicles or synthetic material (preferably a titanium implant, see Chapter 17).

Incus-to-Stapes or Malleus-to-Stapes Reconstruction

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