When marked attic erosion is present in cholesteatoma, especially in adults, we perform a canal wall down (CWD; open) technique to avoid cholesteatoma recurrence that can occur due to absorption of the material used for reconstruction of the attic defect. In cases with sclerotic mastoids, or when middle ear atelectasis is present, a CWD tympanoplasty is also performed. The number of CWD techniques performed in our center is gradually increasing. As described, we now use canal wall up (CWU; closed) technique only in limited cases (< 10%) due to its higher percentage of recurrence and residual cholesteatoma. Today, we mainly apply CWD techniques in cholesteatoma surgery. According to our experience, a well-performed CWD cavity has more chance to prevent second operation with minimal declination of hearing and quality of life.
In CWD tympanoplasty, execution of correct technique is the key for successful surgery. In this technique, since posterior wall of the external auditory canal is removed, the mastoid and the external auditory canal became common communicating cavity exposed to outside after surgery. To avoid postoperative complications, it is very important to create an ideal cavity in the first surgery by following correct procedures such as sufficient saucerization of the cavity and appropriate meatoplasty. Saucerization of the entire cavity and removal of any overhang edges not only increase the working space but also allow soft tissue to fill in the bony defect. That makes the cavity smaller without using any material for obliteration. We always perform meatoplasty in CWD techniques, since this technique allows reduction of raw surface and further makes the cavity relatively small and shallow by enlarging its opening. An adequate meatoplasty is an essential prerequisite to obtain constant success in CWD tympanoplasties. If all procedures are properly performed, the cavity appears small, shallow, rounded in shape, dry, and well epithelized.
On the other hand, a badly performed cavity may appear wet, irregular, and difficult-to-reach periphery. The cavity may be lined with granulation tissue covered by accumulated debris. We have found that technical mistakes commonly seen in the failed cavity are a very narrow meatus and insufficient bone removal such as a high facial ridge, an overhanging edge, and a prominent mastoid tip. Each of these factors impedes self-cleansing of cerumen and debris from the cavity, resulting in inflammatory reaction. In addition, possibility of residual and recurrent cholesteatoma is higher in such cavity.
In this chapter, we describe three techniques used in our center.
If the ossicular chain is severely insulted or the middle ear is involved, we use a CWD tympanoplasty that consists of eradication of the disease from the middle ear with CWD and ossicular chain reconstruction.
For early epitympanic cholesteatoma in which continuation of articulations between the ossicles is preserved, modified Bondy technique yields best result in a single stage according to postoperative hearing, residual and recurrence rate.
For elderly patients with nonserviceable hearing and for cholesteatoma in difficult-to-reach area such as deep tympanic sinus, a safe, dry, self-cleaning ear may be the final goal. In such cases, we sacrifice middle ear function by applying radical mastoidectomy that consists of plugging of the eustachian tube and elimination of air space medial to the tympanic membrane.
The patients who have recurrent cholesteatoma tend to have either poor physiologic function of eustachian tube or the most difficult-to-manage disease status. Revision surgery by preserving the canal wall is likely to expense the patient and family to face new surgery. Therefore, once recurrence occurred, we do not hesitate to convert the procedure to CWD technique by removing the posterior canal wall.
7.1 Canal Wall Down Tympanoplasty
7.1.1 Surgical Steps
Removal of the Posterior Canal Wall
If CWD tympanoplasty has been planned preoperatively, the mastoidectomy can be performed in two ways. After completing mastoidectomy, the shape of the cavity obtained with two procedures should be the same.
Simple mastoidectomy and atticoantrostomy is completed from the posterior cavity just like closed technique. Thinned posterior wall may be removed with either burrs or a rongeur.
Identify first the middle fossa plate. Enlarge the external auditory canal by following the middle fossa plate posteriorly toward the sinodural angle. The sigmoid sinus is identified at this point. The mastoid cavity is gradually opened from anterior to posterior.
The cavity must always be saucerized and gradually deepened. Bony overhangs should be removed from the edges. A round-shaped cavity should be obtained at the end of the drilling.
All the bone covering the middle fossa dura and the sigmoid sinus is thinned with large burrs moved parallel to these structures (▶Fig. 7.1). If bone is appropriately removed, middle fossa dura is clearly identified through the thinned bone by its pinkish color, and the sigmoid sinus is clearly identified by its bluish color (▶Fig. 7.2).
Removal and exteriorization of all air cells posterior to the mastoid segment of the facial nerve and the sigmoid sinus is carried out.
Sufficient bone removal from the sinodural angle is also a part of the procedure.
The facial ridge is lowered evenly by drilling the posterior canal wall with a large cutting burr, with continuous suction irrigation. The burr should be moved always parallel to the course of the facial nerve. Diamond burrs are reserved for final drilling to thin the bony coverage of the nerve. In this procedure, the nerve is skeletonized laterally until the nerve becomes visible through a thin bony shell, but never exposed (▶Fig. 7.3).
In the area of the facial bridge, a burr is moved parallel to the middle fossa plate so as not to hit it accidentally with the burr.
In poorly pneumatized mastoid frequently seen in chronic otitis media, level of the ideally drilled facial ridge is almost in the same plane of the drilled mastoid cavity.
If there is prominent protrusion in anterior or inferior wall, canalplasty should be carried out. The anterior attachment of the facial bridge is lowered sufficiently (▶Fig. 7.4). The anterior meatal skin is cut laterally and detached from the bone toward the annulus. The medially folded meatal skin flap is protected with an aluminum sheet (▶Fig. 7.5). The anterior and/or the inferior meatal walls are drilled to obtain round-shaped cavity. Care should be taken not to expose the temporomandibular joint beneath the anterior wall.
The final shape of the cavity is a reversed pyramid with rounded external edges with no bony overhang in the cavity. Drilling to correct the shape of the cavity should be carried out to such extent.
Management of the Tympanic Cavity
Management of the tympanic cavity should be conducted as soon as possible after sufficient and safe access is established. In this way, hemostasis in the tympanic cavity is achieved before starting reconstruction. Bloodless field is very important for correct arrangement of the reconstruction materials. For that sake, some bone work away from the tympanic cavity may be carried out after managing the tympanic cavity.
The fibrous annulus is detached from the tympanic sulcus posteriorly, and the tympanomeatal flap is elevated to explore the middle ear.
The facial bridge, and then the anterior and posterior buttresses are removed, preferably using a curette (▶Fig. 7.6). Removal of the anterior buttress produces a continuous plane between the middle fossa plate and the anterior canal wall (▶Fig. 7.4).
A bony overhang of the anterior epitympanic recess should be removed to ensure complete control of this area after the surgery. Air cells in this area are removed as much as possible.
Pathology should be carefully dissected from the middle ear not to damage the underlying fragile structures such as the facial nerve, the oval and round windows, the stapes, and the labyrinth. If view of such structures is obstructed by the facial ridge, it may be further lowered (▶Fig. 7.7, ▶Fig. 7.8). The skin of the external auditory canal, the annulus, tympanic membrane, the incus, and/or the malleus may be removed depending on the status of the lesion (▶Fig. 7.9).
When ossiculoplasty is planned, the handle of the malleus and the tendon of the tensor tympani muscle are preserved if possible. Those structures give adequate support to the columella and provide better hearing result.
If the body of the incus is involved but the incudostapedial joint remains intact, cutting the incus in the long process is preferred (▶Fig. 7.10). The remaining portion of the incus may serve as a columella if the facial ridge is lowered sufficiently (▶Fig. 7.11).
To stop bleeding for reconstruction procedures, the tympanic cavity is momentarily packed with small cottonoids after completing management of it.
Management of Pneumatized Temporal Bones
In highly pneumatized mastoid, any invaginated areas and air cells, especially perilabyrinthine and retrofacial cells (▶Fig. 7.12) and cells in attic, should be drilled to complete removal of matrix and to avoid postoperative accumulation of skin debris.
The retrofacial cells are exenterated completely. During this maneuver, care should be taken not to damage the mastoid segment of the facial nerve. Sometimes, in a highly pneumatized mastoid, the retrofacial cells reach the area of the jugular bulb, medial to the facial nerve.
In some cases, the retrofacial cells go far medially to the facial nerve, making complete exteriorization impossible. That area must be obliterated with autologous conchal cartilage.
A prominent, well-pneumatized mastoid tip should be removed to reduce volume of the mastoid cavity (▶Fig. 7.13). Drilling starts from the level of the stylomastoid foramen, and continues posteriorly in a rotatory fashion parallel to the digastric ridge until the tip is undermined. It is important to create a fracture line lateral to the stylomastoid foramen to avoid any traction of the facial nerve in the following process. The remaining bony shell is mobilized and pulled out in a rotatory fashion with a bone rongeur, and detached from the muscle using electrocautery. This amputation of the mastoid tip not only reduces the cavity volume, but also prevents “sink trap effect” that may cause postoperative accumulation of skin debris.
In well-pneumatized bone, large retrosigmoid air cells should also be removed if they are present (▶Fig. 7.14).
Conchal cartilage harvested in meatoplasty, bone paté mixed with blood, and subcutaneous connective tissue are the materials for the obliteration. If the head of the malleus and the body of the incus are not present or removed, the attic may be obliterated with a piece of cartilage and bone paté.
Sometimes, a retroauricular soft tissue flap based anteroinferiorly is used to obliterate the area of the mastoid tip (see ▶Fig. 7.53).
Before reconstructing the tympanic membrane, bleeding should be completely stopped. If tubal dysfunction is suspected, a Silastic sheeting designed to cover the medial wall of the tympanic cavity including the tubal orifice is placed. The eustachian tube and the tympanic cavity are packed with Gelfoam.
The temporalis fascia is grafted underlay whenever it is possible. The overlay technique is used when the anterior annulus is not present. The graft must have abundant extension posteriorly to cover attic and obliterated cells, especially if an ossiculoplasty is performed in the same stage. Another piece of graft may be placed to cover exposed bone. Epithelization is facilitated if the exposed bone is covered with the fascia.
If the tendon of the tensor tympani with the manubrium is preserved, a longitudinal cut is made in the edge of the temporalis fascia. One tongue is placed on the attic and goes into the protympanum, superiorly to the tendon. The other tongue is inserted inferiorly to the tendon, and placed in the tympanic cavity (▶Fig. 7.15).
If the stapes superstructure is present and the facial ridge is sufficiently lowered, the fascia usually touches to the head of the stapes, and second-stage ossiculoplasty may not be required. A thin piece of cartilage placed over the stapes may be helpful. If the incudostapedial joint is left intact, additional height of the long process of the incus over the superstructure may give sufficient contact with the tympanic membrane. If the height is insufficient, a piece of cartilage may be interposed (▶Fig. 7.16).
A meatoplasty should be performed in all the cases. (see Meatoplasty in this chapter).
An experienced surgeon can remove cholesteatoma with CWU technique. However, by removing the posterior wall, wide and safe access to the middle ear can be established without having a big cavity (see ▶Fig. 7.17a, b)
After open techniques, the meatus and the mastoid become a common cavity that is much larger than the original meatus. That makes deep, difficult-to-reach area where self-cleansing or even cleaning in the outpatient clinic is difficult from the original meatus. Accumulation of epithelial debris may cause undesirable repetitive inflammation and even cholesteatoma. In our series of revision, open tympanoplasty formerly operated in elsewhere, meatal stenosis is found in about 60% of failed cavity. To avoid cavity problem, we always perform meatoplasty in open techniques. In this procedure, the meatal skin is folded medially and the opening is enlarged to obtain relatively small, shallow, and easy-to-access cavity. The procedure also covers the cavity with skin, which enhances postoperative healing. After complete epithelization, no special restriction is required including water sports and travel. We believe an adequate meatoplasty that suits the dimension of the cavity is an essential prerequisite to obtain successful result steadily in open tympanoplasties.
Meatoplasty is performed after completing mastoidectomy in every case in which open technique is conducted to adjust the size of the meatus to the cavity.
If conchal cartilage is required for reconstruction, the cavity is packed with cottonoids to achieve complete hemostasis and to prevent blood filling the cavity before starting meatoplasty. If reconstruction is completed, the cavity, especially in the area of tympanic membrane, should be partially packed with the Gelfoam to secure reconstructed structures. Small cottonoids are placed over it. After removing self-retaining retractors, folded gauze is placed on the retroauricular wound to prevent blood from falling down into the cavity. The auricle is positioned in its original place.
Using a nasal speculum, the concha is stabilized. The conchal incision is made from the surface of the auricle (▶Fig. 7.18). The skin, conchal cartilage, and connective tissue are incised together from the middle of posterior meatal wall toward the anthelix, in parallel to the crus of helix (▶Fig. 7.19). Length of the incision required depends on the size of the cavity (larger cavity requires longer incision). At least, the digit finger should pass easily after removing conchal cartilage. The incision, however, never reaches the anthelix.
The skin is held with forceps and dissected from the underlying cartilage using sharp tympanoplasty scissors (▶Fig. 7.20). Then, soft tissue beneath the cartilage is also detached from it (▶Fig. 7.21). After exposing sufficient amount of cartilage, it is removed, triangular in shape, from each side of the edges (▶Fig. 7.22). The amount of cartilage removed varies depending on the size and contour of the cavity. However, it is important to preserve cartilage in the crus of the helix. Otherwise, cosmetic deformity may follow.
If the removal is insufficient, the cartilage can be removed from the retroauricular wound. The auricle is folded anteriorly and held by a scrub nurse. The cartilage is further trimmed by removing a crescent-shaped piece from the edge. Sufficient removal of the cartilage facilitates folding of the skin medially, which serves not only for reducing raw surface in the cavity but also for preventing postoperative perichondritis caused by inappropriate exposure of the resected edge in the wound. To further facilitate medial folding, the skin flaps may be thinned by trimming subcutaneous soft tissue.
From the retroauricular wound, the meatal skin flaps are folded posteriorly (▶Fig. 7.23), and ideal position for the cavity is estimated. These flaps are finally sutured superiorly and inferiorly to the musculoperiosteal layer with 3/0 Vicryl (▶Fig. 7.24). Make sure that the raw surface in the edge of the cartilage is fully covered by conchal skin or soft tissue.
After suturing the meatal skin flaps, center of the entire conchal cartilage may be pulled posterosuperiorly and posteroinferiorly. This may cause anterior rotation of the entire auricle, making the auricle prominent postoperatively. Useful technique to avoid this cosmetic problem is to put a couple of sutures deeply in soft tissue more lateral to the meatus, and retract the auricle posteriorly.
The cavity is packed with Gelfoam soaked in physiologic saline. Generally, no antibiotic ointment is used. The retroauricular incision is closed by suturing the skin in two layers, or in one layer with Steri Strip. Usually, after radical mastoidectomy and modified Bondy technique, second-stage operation is not necessary. Epithelization of the cavity is completed within 8 weeks in most of the cases.
7.1.2 One-Stage Surgery in Canal Wall Down Tympanoplasty
As mentioned, staged surgery where cholesteatoma is removed in the first stage and removal of residual disease, if any, and reconstruction of ossicular chain are performed in the second stage usually gives better hearing result. Status of mucosa around the oval window and stability of the previously reconstructed tympanic membrane mainly give such difference. The second-stage surgery can be carried out easily under an ear speculum under local anesthesia as far as the first-stage canal wall down procedure is conducted correctly giving sufficient access to the tympanic cavity. Main drawbacks of such strategy are necessity of the other surgery and postoperative hearing disturbance. In limited cases, one-stage surgery is preferred especially in better hearing ear with healthy mucosa in the tympanic cavity especially around the stapes. In marginal cases to which modified Bondy technique might be applied, actual surgical procedure is decided in the operating field. If there is any uncertainty of complete removal from the area medially to the ossicular chain, the surgeon should remove some part of ossicular chain. Since mucosa in the tympanic cavity usually keeps good condition, such cases are good candidates for one-stage surgery.
7.1.3 Staged Surgery in Canal Wall Down Tympanoplasty
In many cases of cholesteatoma, the tympanic cavity is involved and the tympanic membrane is retracted. The tympanic cavity may get scar or granulation tissue, or the tympanic membrane may be adherent to the medial wall. Closure of perforations may be required. In such situation, unpredictable factors such as rescarring of the tympanic cavity, adhesion of the reconstructed tympanic membrane, and displacement of the columella due to postoperative migration of the tympanic membrane may interfere postoperative sound transmission. To obtain more stable result, the surgery is often staged, and the ossicular chain is reconstructed in the second stage. In addition, residual disease, if any, can be removed and retraction pocket may be corrected in the second stage, to enhance curability of the entire surgery.