Tympanoplasty Surgery Technique

A tympanoplasty is an operation on the ear to treat conductive deafness by repairing a hole in the eardrum (myringoplasty) or by repositioning or reconstructing the diseased ossicles (tiny bones in the middle ear that conduct sound).

Tympanoplasty Surgery  - Underlay and Overlay Techniques - technical

Also known as: Ear drum repair; Lateral graft technique; Medial graft technique; Myringoplasty; Tympanic membrane repair; Type I tympanoplasty; Undersurface repair

Definitions

Allograft: A graft of tissue taken from a donor of the same species, but with a different genetic makeup from the recipient.

Anterior tympanomeatal angle: The angle created by the anterior wall of the ear canal and the anterior surface of the eardrum.

Auricle: The part of the external ear that projects outward from the head. A postauricular approach indicates that the initial incision is made behind the ear (auricle).

Autologous tissue: Tissue derived or transferred from the same individual’s body.

Cholesteatoma: A cyst-like mass lined with stratified squamous epithelium filled with desquamated debris typically involving the middle ear and/or mastoid cavity.

Epitympanic space: The upper portion of the middle ear space that contains the head of the malleus and body of the incus.

Eustachian tube: The slender tube that runs from the middle ear to the nasopharynx (upper portion of the throat) that serves to equalize pressure on either side of the eardrum.

External auditory canal: The auditory canal (ear canal) leading from the opening of the external ear (auricle) to the eardrum.

Homograft: Synonymous to allograft, but implying here, the use of a whole tympanic membrane (ear drum).

Incus: The anvil-shaped bone that connects the first ear bone (malleus) to the third (stapes).

Malleus: The hammer-shaped bone that is the outermost of the three small bones in the middle ear.

Mastoidectomy: Surgical removal of mastoid air cells and/or part or all of the mastoid process. The mastoid cavity underlies the bone directly behind the ear.

Middle ear: The narrow air-filled space between the ear drum and the outer wall of the inner ear containing the ossicular chain (three small bones) that transmits sound energy to the inner ear.

Myringoplasty: Surgical repair of defects or injuries limited to the tympanic membrane without lifting the tympanic membrane from its position in the ear canal.

Perichondrium: The fibrous membrane that covers the surface of cartilage.

Stapes: The stirrup-shaped bone in the middle ear that transmits sound vibrations from the incus to the inner ear.

Temporalis fascia: A layer of connective tissue overlying the temporalis muscle. The temporalis muscle is a fan-shaped structure that originates from the squama of the temporal bone and inserts along the anterior border of the ramus of the mandible. It is a major closing muscle of the jaw.

Tympanic membrane: The membrane separating the external from the middle ear. Also known as the eardrum.

Tympanic membrane perforation: An opening or defect in the eardrum.

Tympanomeatal flap: A surgically created flap of tissue that consists of a segment of ear canal skin and the attached ear drum that are lifted together in order to enter the middle ear space.

Tympanoplasty: Surgical repair of defects or injuries of the tympanic membrane (ear drum) and/or middle ear ossicles (ear bones). The tympanic membrane is lifted from its position in the ear canal during a tympanoplasty procedure.

Xenograft: A graft of tissue taken from a donor of a one species and grafted into a recipient of another species.

Purpose of Tympanoplasty

The approach and specific technique used to repair tympanic membrane perforations are influenced by the size and location of the perforation, presence and extent of middle ear and mastoid disease, and the particular experience of the surgeon. Both the underlay and overlay grafting techniques can be equally successful for restoring the integrity of the tympanic membrane if performed in a meticulous manner with particular attention to exposure. The primary goals of either technique are to produce a thin conically shaped vibratory surface, eliminate and prevent infection, and restore the hearing mechanism. The repair of subtotal tympanic membrane perforations and large anterior perforations are often challenging regardless of the grafting technique employed, while the repair of isolated posterior tympanic membrane perforations are often less cumbersome. This section focuses on specific techniques for managing these types of tympanic membrane perforations.

Principle

Historical Perspective

The first attempt to close a tympanic membrane perforation dates back to 1640, when Banzer (1651) published an account of using pig’s bladder stretched across an ivory tube placed against the tympanic membrane opening. In 1853, Toynbee (1853) successfully improved hearing by placing a small rubber disk attached to a silver wire over a perforation in the tympanic membrane. More simplified techniques were later introduced by Yearsley (1863) in 1863 and by Blake (1877) in 1877. Yearsley used a cotton ball placed over the perforation, while Blake introduced the concept of placing a thin paper patch over the tympanic membrane. The use of silver nitrate chemical cautery to promote spontaneous healing of tympanic membrane perforations was proposed by Roosa (1876) in 1876. Modifications of this technique with the use of paper patch augmentation were later described by Joynt (1919) and Derlacki (1953). The use of autologous tissue to achieve a more permanent and reliable repair did not occur until the 1950s. Until then there had been considerable reluctance to attempt closure of a tympanic membrane perforation in a chronically draining ear. With the advent of antimicrobial therapy and the introduction of the operating microscope, there was a renewed interest in establishing techniques in tympanoplasty surgery. In 1952, the tympanoplasty procedure was popularized by Wullstein (1952), and Zollner (1952) through the use of full-thickness and split-thickness skin grafts. However, with full- and split-thickness skin grafts laid over a denuded tympanic membrane remnant, there was a propensity toward delayed healing, granulation formation, infection, and iatrogenic cholesteatoma. Sooy (1956) and House and Sheehy (1961) recognized the potential for improved results with the use of external auditory canal skin. While early results were promising, late failures due to infection and loss of graft integrity and reperforation were realized. The use of autologous vein grafts was introduced in 1960 by Shea (1960) and Tabb (1960) for the underlay repair of incidental tympanic membrane perforations during stapedectomy. Austin and Shea (1961) extended the use of vein grafts for the underlay repair of small to medium-sized central perforations. This grafting material, however, tended to atrophy after a few months resulting in an occasional reperforation. In an effort to establish more durable repair, Heermann (1960) in 1960, and Storrs (1961) in 1961, reported the use of temporalis fascia for the repair of tympanic membrane perforations using an underlay technique. The popularity of temporalis fascia as a grafting material of choice for underlay and overlay tympanoplasty procedures has persisted over the years. Although a variety of grafting materials have since been introduced including perichondrium, cartilage, periosteum, allografts, homografts, and xenografts, autologous fascia is considered the standard by which other grafting materials are measured.

Grafting Materials

A variety of autologous tissues have been used historically as grafting materials for tympanoplasty procedures with reported success rates of 81–98% (Glasscock et al. 1982; Halik and Smyth 1988; Rizer 1997; Cueva 1999; Aidonis et al. 2005; Djalilian 2006; Cabra and Monux 2010). Temporalis fascia continues to be the grafting material of choice because of its ready availability in the surgical field, low metabolic requirements, and favorable revascularization potential, durable composition, and thinness, and its ease of preparation and placement. A sufficient quantity may be obtained even in revision cases by extending the incision superiorly. Obtaining fascia in revision cases can often be difficult due the loss of a reliable plane of dissection between the superficial layer of the deep temporal fascia and the overlying subcutaneous tissues. The scar bed can be circumvented by identifying an unadulterated fascial plane anteriorly above the external auditory meatus. Further dissection is then carried superiorly before a proper plane is created posteriorly through the scar bed. Temporalis fascia can be cut to the proper dimension, delivered into the canal, and positioned for tympanic membrane repair while in its dessicated form. Rehydrating the graft with a drop of physiologic saline may further facilitate proper placement and final positioning. Although perichondrium is a suitable graft material for smaller central tympanic membrane perforations, this section focuses on the use of fascia for the repair of selected tympanic membrane perforations using either the underlay or overlay technique.

Surgical Preparation

Patient positioning and preparation of the surgical field remains fairly consistent whether performing the underlay or the overlay technique or whether the repair of the tympanic membrane perforation is performed through a transcanal or postauricular approach. The differences are related primarily to the anatomic locations requiring the administration of local anesthesia as dictated by the surgical approach and the graft harvest site (temporalis fascia vs tragal perichondrium). The surgical approach is also influenced by the extent of middle ear and/or mastoid pathology. Chronic middle ear and/or mastoid inflammatory disease with or without cholesteatoma, may necessitate a postauricular approach in order to optimize exposure of middle ear structures or to perform a mastoidectomy. Uncomplicated, isolated posterior tympanic membrane perforations can be repaired through a transcanal or endaural approach and will provide adequate exposure for evaluation and repair of ossicular chain abnormalities.

Patients are rarely administered perioperative antibiotics and their use would be considered in the event of disruption of the dural surface with cerebrospinal fluid leakage, violation of the labyrinth, or contamination of the surgical field. The majority of patients receive general endotracheal anesthesia. Paralytic agents are avoided and there is little concern for the use of nitrous oxide. The patient is placed in a neutral supine position with the head secured with clear elastic tape on a standard foam headrest. The head is turned at a 30 angle away from the operative side and the head shifted gently away from the operative side in order to create a more obtuse angle between the head and the shoulder. Surgical lubrication is applied to the postauricular hair and the hair combed back. The hair is not shaved unless it interferes with the proposed incision site for the postauricular approach or for obtaining the temporalis fascia graft. Facial nerve monitoring is used in all cases and electrode leads are placed prior to the application of topical antiseptics. Two percent Lidocaine with 1:100,000 epinephrine is injected along the proposed postauricular incision site (postauricular approaches and temporalis fascia graft site), the meatus, and, if necessary, the posterior aspect of the tragus. The surgical site is scrubbed with povidone-iodine soap followed by painting the site with povidone-iodine solution. The external auditory canal is initially protected from exposure of the iodinebased prep. A cotton-tipped swab soaked in povidoneiodine solution is applied to the meatus as a final step. The surgical site is draped (“picture framed”) with four sterile surgical towels, dried with a sterile towel, and covered with a iodophor impregnated clear adhesive drape. The adhesive drape serves to secure the sterile towels to the surgical site, hence, obviating the need for staples. The remainder of the field is draped in a standard sterile manner.

Underlay Technique: Wide Exposure Anterior Suspension Technique

The repair of subtotal tympanic membrane perforations (Fig. 1a) and large anterior perforations (Fig. 1b) pose a challenge, with both the overlay and underlay techniques having definable shortcomings. The overlay technique has the propensity toward blunting of the anterior tympanomeatal angle, medial canal fibrosis, and graft lateralization, while the underlay technique has the tendency to fail anteriorly due to lack of graft support and the influences of negative middle ear pressure. External auditory canal anatomic considerations including an anterior canal wall bulge and isolated bony prominences can impair proper visualization, graft placement, and postoperative healing. The wide exposure anterior suspension technique addresses these concerns and provides a means for reducing failure in underlay tympanoplasty for near total and large anterior tympanic membrane perforations. Variations of this technique have been previously described (Larrabee and Tabb 1979; Primrose and Kerr 1986). The advantages of this technique include complete exposure of the middle ear for removal of disease, greater exposure for prosthesis placement, facilitated observation of the round window reflex, reduced risk of anterior blunting and medial canal fibrosis, avoidance of graft lateralization, reduced risk of canal stenosis, and easier postoperative evaluation and cleaning.

Technique

A postauricular incision is made approximately 3 mm posterior to the postauricular crease (Fig. 2a, b). The incision is carried deep to the level of the superficial layer of the deep temporal fascia superiorly and the mastoid periosteum inferiorly, angling anteriorly in the direction of the bony-cartilaginous junction. A temporalis fascia graft is obtained (Fig. 3) and spread onto a teflon block to air dry on the back instrument table. An anteriorly based mastoid periosteal flap is reflected anteriorly and the suprameatal spine and posterior lip of the external auditory canal wall are identified. An incision is made through the posterior canal skin just medial to level of the suprameatal spine and the external auditory canal is exposed (Fig. 4). A 1–2 mm crescent piece of skin may be excised from the lateral aspect of the transected canal to provide additional exposure. A self-retaining retractor is used to reflect the periosteal flap and the auricle anteriorly to complete the exposure. This approach should provide clear visualization around the borders of the perforation and the entire annulus. The perforation must then be prepared for eventual grafting. The edge of the perforation is trimmed circumferentially and the undersurface of the membrane is gently scraped to ensure removal of squamous epithelium and facilitate healing (Fig. 5). A classic posterior tympanomeatal flap is developed by incising the canal skin at the six and twelve o’clock positions (Fig. 6). The posterior flap is elevated anteriorly and the middle ear inspected for disease and mobility of the ossicular chain (Fig. 7). If visualization of the anterior tympanomeatal angle is impeded by a prominent anterior canal wall bulge, then an anterior canalplasty is necessary. An incision is made approximately 1 mm lateral to the anterior annulus and a laterally based anterior canal flap is back-elevated and tucked into the transected meatus (Fig. 8a, b). A small piece of merocel sponge is inserted into the transected meatus to stabilize the flap and protect it from the rotating drill bit during the canalplasty procedure. The posterior flap is reflected onto the tympanic membrane and covered with a piece of merocel sponge or compressed gel foam. At this point, the entire bony canal is exposed and prepared for drilling. A series of cutting and diamond drill bits are used to perform the canalplasty with successively smaller bits employed as drilling progresses from lateral to medial. The extent of bone removal anteriorly is limited by the position of the capsule of the temporomandibular joint. Typically, the anterior canal wall bulge can be removed to provide unimpeded visualization of the anterior annulus without risking penetration of the temporomandibular joint capsule (Fig. 9). Dehiscences measuring 3 mm or less usually do not require reconstruction and rarely influence healing of the anterior canal wall skin. The extent of drilling along the posterior canal wall is dictated by the presence of disease in the middle ear and/or epitympanic spaces. Assuming the absence of middle ear disease and a normal ossicular chain, drilling can be limited to removal of the lateral lip of the posterior bony wall and any prominent bony ledges or bulges along the midportion of the posterior canal. The posterior canal wall should be drilled in such a way to create a straight flat surface to provide an unimpeded line of sight from the lateral lip of the bony canal to the annulus. It is important to recognize the position of the chorda tympani nerve as it exits the posterior canal wall in proximity to the posterior annulus (posterior iter) in order to avoid iatrogenic injury. Placement of the temporalis fascia graft along the posterior inferior aspect of the canal wall can be facilitated by creating a flat surface for optimal positioning of the fascia graft. The anatomical configuration of the bony canal should ultimately favor a cylindrical shape from that of an hourglass configuration (Fig. 10). The fascia graft is trimmed to the proper width and length as governed by the size of the tympanic membrane perforation and width of the canal following canalplasty (usual dimensions 1.5 2.5 cm). A tab measuring approximately 3 mm in width and 4 mm in length is fashioned at the leading edge of the fascia graft. An opening is created in the mucosal lining between the anterior fibrous and bony annulus measuring approximately 5mmin length (Fig. 11). The fascia graft is advanced along the posterior canal wall into the middle ear space deep to the malleus handle. The anterior tab is easily identified through the tympanic membrane perforation and the graft is further advanced toward the eustachian tube orifice. Using either an angled pick or a #3 suction cannula, the tab can be pulled through the annular opening and applied to the anterior canal wall (Fig. 12a, b). The middle ear is packed with compressed gelfoam pledgets soaked in an antibiotic-corticosteriod otic suspension and the posterior tympanomeatal flap and fascia graft are returned to the posterior canal wall position. The anterior canal skin flap is retrieved from the meatus and redraped onto the anterior canal wall. There is typically a 2–4 mm foreshortening of the anterior canal skin flap when reapplied to the canal wall (Fig. 13). Additional skin grafting to cover this gap is rarely necessary. The largest gaps of exposed canal bone will occur superiorly and inferiorly with their dimensions determined by the extent of the canalplasty performed. If necessary, thin split-thickness skin grafts are harvested from the posterior aspect of the auricle to cover these areas of exposed bone. The canal is packed with a “rosebud” dressing consisting of Bacitracin ophthalmic ointment impregnated polyester strips to line the canal soft tissue followed by a series of antibiotic-corticosteroid soaked merocel ball sponges (small size for the medial and large for the lateral aspect of the canal). The lateral ends of the polyester strips are folded over one another in such a way to prevent trapping of the material behind soft tissue and the auricle returned to its posterior position for wound closure. A large merocel sponge pack is then placed into the meatus (Fig. 14). The postauricular incision is closed in layers and the skin closed with a running 4.0 chromic suture in a subcuticular fashion. Steristrips are placed over the incision site as well as the posterior surface of the auricle if a skin graft has been harvested. A firmly compressive mastoid dressing is then placed.

Postoperative Care

The patient is instructed to remove the mastoid dressing after 24 h and to begin delivering an antibioticcorticosteroid otic suspension onto the outer canal packing following the first postoperative week. The canal packing is removed at 2 weeks postoperative and the patient is asked to continue using the prescribed ear drops twice per day for an additional 2 weeks. They are placed on 2% acetic acid solution twice a day for the second postoperative month and scheduled to return for an audiogram at the 2-month postoperative visit when the majority of the initial healing process is complete. Alternatively, antibioticcorticosteroid soaked gelfoam pledgets may be used to pack the medial aspect of the canal in patients who do not require an anterior canalplasty or in pediatric patients who may not tolerate removal of a rosebud dressing in the clinic.

Alternative Approaches to the Technique

If an anterior canal skin flap has not been elevated for canalplasty, a 5 mm incision can be made approximately 2 mm lateral to and coplanar with the fibrous annulus and a small anterior canal skin flap backelevated for positioning of the anterior tab of the fascia graft (Fig. 15).

Problems and Variations During Tympanoplasty Surgery

The wide exposure anterior suspension technique has applications beyond isolated perforations of the anterior tympanic membrane or large central perforations. The wide exposure aspect of this technique provides the means for removing disease within the posterior recesses of the middle ear, the region of the oval window niche, and tympanic portion of facial nerve, and the anterior and posterior epitympanic spaces. The surgeon must be cognizant of the relative position of the second genu and vertical segment of the facial nerve before embarking on an aggressive transcanal approach to middle ear disease. The risk of injury to the chorda tympani nerve is greater with a more aggressive approach making elective sacrifice more likely beyond that which may be indicated by the extent of the disease. Extensive removal of bone along the posterior superior aspect of the canal in conjunction of removal of the head of the malleus will provide adequate exposure for removal of disease in the epitympanic spaces. The incudostapedial joint is typically separated prior to the removal of bone along the medial aspect of the canal to avoid the potential for high-frequency sensorineural hearing loss due to contact between the rotating drill bit and the malleus or incus. Any disease remaining in the antrumor aditus ad antrum can be removed through a standard transmastoid approach. Reconstruction of the posterior superior canal wall defect can be achieved using tragal cartilage (perichondrial hinge technique) if necessary.Removal of bone along the medial aspect of the posterior canal wall will facilitate prosthesis placement as a result of an increased distance between the malleus handle and canal wall. This is particularly evident when using the tympanic membrane as the contact surface for the head of the prosthesis. Additional advantages of this technique include a reduced risk for anterior blunting, medial canal fibrosis, canal stenosis and graft lateralization, and easier postoperative evaluation and cleaning.

Reconstruction of the Posterior Superior Canal Wall (Perichondrium Hinge Technique)

Exposure of the posterior epitympanum can be achieved by removing bone along the medial aspect of the posterior superior canal wall. Extensive bone removal for the purposes of exploration and removal of disease may result in a large defect requiring reconstruction. A cartilage-perichondrium composite graft is used to repair the canal wall defect and reduce the potential for postoperative graft retraction into the posterior epitympanum. An incision is made along the posterior surface of the tragus approximately 5 mm. from its lateral extent (Fig. 16a). The incision is carried through skin and cartilage and curved iris scissors are used to bluntly dissect a plane between the skin and the posterior perichondrium and between the deep tissues overlying the parotid gland and the anterior perichondrium of the tragal cartilage (Fig. 16b). A 6 8 mm. segment of cartilage is removed, placed on a teflon block, and trimmed to the appropriate dimensions that correspond to the canal wall defect. The perichondrium on one side is elevated from the cartilage allowing approximately 1 mm to remain attached at one end (Fig. 17a, b). The cartilageperichondrium graft is placed into the defect and suspended from the canal wall bone using the hinged perichondrial flap (Fig. 18). The intact perichondrium should face the epitympanic space. The graft should be sized in such a way to prevent contact with either the tympanic fallopian canal or the medial surface of the posterior epitympanum to allow ventilation between the mastoid antrum and the epitympanic and middle ear spaces. The tragal incision is closed with interrupted 5–0 chromic sutures. The normal contour of the lateral surface of the tragus is preserved using this technique.

Underlay Technique: Posterior Perforations

Posterior tympanic membrane perforations (Fig. 19) can be repaired typically through a transcanal approach using an underlay technique. Patient positioning and skin surface preparation with antiseptics are similar to that described for the postauricular approach. Facial nerve monitoring is used in all cases. Two percent Lidocaine with 1:100,000 epinephrine is injected inferiorly and superiorly along the posterior aspect of the meatus. An appropriately sized ear speculum is held in position with a speculum holder. If necessary, an incision is made along the superior aspect of the meatus in order to increase the dimension of the meatal opening and allow for the use of a larger speculum. Other than allowing the use of both hands, the speculum holder also serves as a support for the surgeon’s fingers. Careful microscopic inspection of the circumference of the perforation edge should be conducted in order to determine the presence of squamous epithelium migrating around the edge and along the medial surface of the tympanic membrane. In cases where it is clear that squamous epithelium is not present at the perforation edge, removing a rim of tissue along the circumference of the perforation may be unnecessary. In such situations, a right angle pick is used to “burnish” the edge of the perforation by running the pick along the undersurface of the perforation margin. Temporalis fascia is obtained through a 2 cm incision made approximately 2–3 mm posterior to the superior aspect of the postauricular sulcus. Surgical planes are created between the overlying areolar tissue laterally and the muscle bed medially in order to avoid the need for removal of excess tissue before graft drying. The graft is placed on a Teflon block, pressed firmly with a gauze sponge, and allowed to air dry on the back instrument table. External auditory canal incisions are made at the six and twelve o’clock positions and carried laterally to the junction between the thick skin of the meatus and the thin epithelium overlying the bony canal. The two incisions are connected at their lateral extent with a separate horizontal incision made just medial to the thick skin of the meatus. A medially based posterior tympanomeatal flap is elevated with a round knife to the level of the fibrous annulus. The fibrous annulus is elevated with a Rosen pick with particular attention to avoid injury to the chorda tympani nerve at the superior extent of the annular rim. The integrity and mobility of the ossicular chain is evaluated. The fascia graft is then trimmed to an appropriate dimension that will provide at least 1 mm of “underlap” distance between the superior margin of the perforation and the superior margin of the graft and likewise for the inferior margins. The leading edge of the graft should be advanced to a position at least 2mm anterior to the malleus and the posterior aspect of the graft should have enough length to allow placement along the posterior canal wall (Fig. 20a, b). Once the graft has been advanced anteriorly between the undersurface of the malleus handle and the cochlear promontory, gelfoam pledgets soaked in an antibioticcorticosteroid otic suspension are placed medial to the graft and advanced anteriorly into the protympanum in order to support the anterior extent of the graft. Occasionally, small pieces of dry compressed gelfoam are advanced anteriorly against a bed of previously placed moistened gelfoam in order to ensure proper support of the graft anteriorly. The remainder of the middle ear space is filled with antibiotic- corticosteroid soaked gelfoam peldgets and the posterior aspect of the fascia graft and overlying tympanomeatal flap laid against the posterior canal wall. The external auditory canal is packed with antibiotic- corticosteroid soaked gelfoam pledgets to the level of the lateral extent of the tympanomeatal flap. An alternative technique for closing a posterior tympanic membrane perforation, measuring less than 4 mm in its greatest dimension, is the underlay direct repair technique using tragal perichondrium. With this transcanal technique, elevation of the canal skin is avoided, there is no need for a postauricular incision for graft harvesting, and the repair can be done rather quickly. Tragal or conchal perichondium may be used. Perichondrium tends to be easier to handle when rehydrated as compared to temporalis fascia. This is particularly beneficial when positioning the graft under the perforation margin against a bed of moistened gelfoam. This procedure may be a reasonable alternative when the following conditions are met: dry posterior perforations (although this technique has been used with success for anterior perforations less than 4mm diameter), no evidence of migration of squamous epithelium along the medial surface of the tympanic membrane, intact ossicular chain (as suspected by virtue of the degree of conductive component on preoperative audiometry and/or based on otomicroscopic findings), non-marginal perforations with respect to the fibrous annulus posteriorly or the malleus handle anteriorly. The perforation edge is managed in the same way as described for the underlay technique. Gelfoam soaked in antibiotic-corticosteroid otic suspension is placed through the tympanic membrane opening in order to establish a bed of support for the perichondrium graft. The leading edge of the dried graft is tucked under the anterior aspect of the perforation. The graft quickly becomes rehydrated and can be “buckled” in order to advance the remaining edges medial to the tympanic membrane remnant (Fig. 21). This can often be achieved with either a Rosen or right angle pick. The external auditory canal is then packed with antibiotic-corticosteroid soaked gelfoam pledgets.

Postoperative Care

Packing is removed at 2 weeks postoperative and the patient is instructed to use an antibiotic-corticosteroid combination otic suspension twice per day for at least 2 weeks. Patients are typically reevaluated 1 month following their first postoperative appointment and an audiogram is obtained at 2 months postoperative.

Overlay Technique

The approach and initial canal incisions for the overlay technique in the repair of large anterior and subtotal tympanic membrane perforations are the same as those described for the underlay technique. Incisions are made in the canal at the six and twelve o’clock positions and are carried laterally to the level of the meatal posterior canal skin incision. A third incision is made 2 mm lateral to and coplanar with anterior annulus and extends inferiorly and superiorly to connect the six and twelve o’clock incisions. This outlines a laterally based anterior canal skin flap that is back-elevated and tucked into the transected meatus. Care must be taken to avoid fenestrating or tearing the flap and to complete its elevation to the level of the lateral lip of the tympanic ring. The posterior tympanomeatal flap is elevated to the level of fibrous annulus. At this point the skin flap must be separated from the annulus and dissection continued anteriorly to separate the squamous epithelial layer from the fibrous layer of the tympanic membrane (Fig. 22). The incision between the canal skin flap and annulus can be made with a sharp sickle knife and dissection over the tympanic membrane completed with a round knife (Fig. 23). Care must be taken to ensure that epithelium has also been removed from the anterior fibrous annulus. If an adequate plane is created between the squamous epithelial and fibrous layers, extending the dissection over the anterior annulus is typically simplified. The posterior tympanomeatal skin flap, in continuity with the epithelium dissected from the annular ring and fibrous tympanic membrane remnant, can now be removed and placed on the back table in physiologic saline for later use. To achieve the proper canal anatomy for graft placement and provide an optimal environment for healing, a circumferential canalplasty is necessary. Drilling proceeds from anterior superior to posterior inferior and from lateral to medial using a series of cutting and diamond drill bits. The canalplasty procedure for the overlay technique is very similar to that of the aforementioned underlay technique. The primary objective is to improve exposure and create a 90 angle between the tympanic membrane and the anterior and anterior inferior canal wall. In addition to the risk of temporomandibular joint capsule exposure during the removal of bone along the anterior canal wall, drill contact with the lateral process of the malleus must also be avoided. The extent of posterior canal wall drilling is influenced by the need for additional exposure in the posterior recesses of the middle ear space (sinus tympani) and/or the epitympanic spaces for removal of disease. A posterior tympanotomy will often allow complete evaluation of the ossicular chain to determine the presence and extent of the disease within the middle ear space. If additional exposure is required, bone along the medial aspect of the posterior superior canal wall can be removed. The position of the chorda tympani nerve must be identified before proceeding, however. Adequate exposure should allow inspection of the oval and round window niches, evaluation of the integrity and mobility of the ossicular chain, and identification of disease within the epitympanic spaces. Copious irrigation of the middle ear space to remove bone dust is recommended at this point. Bone dust that remains in contact with the incus or within the oval window niche in proximity to the stapes may cause fixation when healing is complete. The tympanic membrane is then prepared for overlay grafting using temporalis fascia. The drum is reinspected for any remnants of squamous epithelium and the fascia is cut to the proper shape and length to allow for a 7–8 mm overlap of the posterior canal wall and a 1–2 mm overlap of the anterior annulus. The graft typically measures 1.5 2.5 cm. A slit is cut along the side of the leading edge of the graft to accommodate the malleus (Fig. 24). Incisions are made along the anterior and posterior surfaces of the malleus handle and the anterior fibrous annulus is separated from the bony annulus from the one o’clock to five o’clock position. Separating the anterior fibrous annulus (in continuity with the mucosal lining of the protympanum) from the bony annulus creates a potential space or sulcus for “wedging” the leading edge of the fascia graft and reducing the risk of graft lateralization. The graft is led into the canal and the apex of the lateral slit is advanced under the malleus and pulled superiorly to the level of the neck. The anterior aspect of the slit overlaps the lateral process and region of the pars flaccida. The leading edge of the graft is then tucked into the anterior annular sulcus in order to stabilize its position (Fig. 25). The posterior aspect of the graft is unfurled and spread along the posterior and superior aspects of the canal wall. The laterally based anterior canal skin flap is removed from the transected meatus and redraped. The posterior canal skin is used to reline the superior canal wall and split thickness skin grafts harvested from the posterior auricle are used to reline the posterior and inferior aspects of the canal wall. All skin grafts are reinspected after placement to ensure that the edges are unfurled and that the squamous epithelial surface faces the canal lumen. They are positioned at the level of the annulus-canal wall junction avoiding any overlap of either the annulus or neighboring skin graft (Fig. 26). The canal is packed using a “rosebud” dressing as previously described for the underlay technique. The lateral aspect of the canal meatus is packed with a merocel sponge soaked in an antibiotic-corticosteroid otic suspension. Closure of the postauricular incision and dressings are the same as those described for the underlay-anterior suspension technique.

Postoperative Care

Postoperative care instructions for the overlay tympanoplasty technique are similar to those described for the underlay-anterior suspension technique. Because of a greater degree of mobilization of canal and tympanic membrane tissue and a larger surface area requiring grafting, patients who undergo the overlay technique may need more frequent and longer followup to ensure satisfactory healing. Patients must be reminded of the importance of adhering to the postoperative instructions including the use of ototopical agents and the avoidance of water penetration into the canal during the first 6–8 weeks postoperative.

Indications and Contraindications

Preoperative Evaluation and Patient Selection

The decision to recommend surgical repair of a tympanic membrane perforation may be influenced by several factors identified at the time of initial evaluation. These factors include: hearing status, age of the patient, size and location of the perforation, mechanism of perforation, status of the contralateral ear, function of the eustachian tube, chronicity of ear disease and the persistence of otorrhea, and the coexistence of inhalant allergy and the degree of control of symptoms. In addition, preoperative counseling should determine the expectations of the patient or parent(s) and assess their reliability for adhering to postoperative instructions and to a follow-up schedule. The general health of the patient and their suitability for a surgical procedure using either general anesthesia or a local anesthetic with sedation should also be determined. An audiogram is obtained in every patient. The severity of the conductive component of hearing loss is assessed in order to determine the likelihood of an ossicular chain abnormality contributing to the degree of conductive loss. This may influence the surgical approach, the technique used for repairing the tympanic membrane, and the potential for staging the procedure. The timing of tympanoplasty in young children remains a controversial subject in terms of agerelated factors that may influence long-term success. Children are known to have frequent upper respiratory tract infections, high rates of otitis media, and poor eustachian tube function. These factors may lead to an increased rate of failure in pediatric tympanoplasty. Although many studies cite a success rate from 60% to 99% for tympanoplasty in adults, the reported success rates in children range from 35% to 94% (Lin and Messner 2008). While age alone has been found to be a significant independent factor in some studies (Vrabec et al. 1999; Emir et al. 2007), others have shown no correlation between age and success of tympanoplasty in the pediatric population (Chandrasekhar et al. 1995; Umapathy and Dekker 2003; Merenda et al. 2007). The size and location of tympanic membrane perforations has also been studied in the literature in an effort to determine the influence of these two factors on successful outcome. While some studies have suggested that perforations greater than 50% of the drum surface negatively influence outcome (Dornhoffer 2003; Onal et al. 2005; Emir et al. 2007), others have found no correlation between either size or location and the rate of success (Adkins and White 1984; Chandrasekhar et al. 1995; Uyar et al. 2006; Merenda et al. 2007). In addition, the mechanism responsible for the development of a perforation (chronic or recurrent otitis media vs traumatic event) has not been shown to have an impact on the outcome of repair (Cohn et al. 1979; Chandrasekhar et al. 1995). The location of a tympanic membrane perforation has also been examined in the pediatric tympanoplasty literature. Although the rate of success for closing anterior perforations has been previously described as less satisfactory (Halik and Smyth 1988; Koch et al. 1990), more recent studies have demonstrated no difference in outcome when analyzing results according to perforation site (Chandrasekhar et al. 1995; Singh et al. 2005; Albera et al. 2006). While this may be encouraging, it is difficult to discern from the literature how size and location might influence the surgical approach and technique in an individual case as these variables are difficult to control when making comparisons. Poor eustachian tube function, as assessed by the status of the contralateral ear (tympanic membrane retraction, perforation, or effusion), might be considered as an important prognostic factor based on findings of several authors (Collins et al. 2003; Uyar et al. 2006; Merenda et al. 2007). On the contrary, others have shown no association between the status of the contralateral ear and the likelihood for successful repair of the ipsilateral ear (Chandrasekhar et al. 1995; Singh et al. 2005; Albera et al. 2006). Furthermore, while favorable results on preoperative eustachian tube testing may predict a good outcome, poor test results have a low prognostic value (Manning et al. 1987). The actively draining ear must be addressed preoperatively in order to establish a dry, infection free ear at the time of surgery. An ototopical antimicrobial/steroid combination agent is prescribed and an oral antibitiotic is added when clinically indicated. While some studies have shown a negative impact on successful outcome in draining ears (Black 1992; Uyar et al. 2006), others have demonstrated no difference in success rates between wet and dry ears at the time of surgery (Adkins and White 1984; Chandrasekhar et al. 1995; Onal et al. 2005; Albera et al. 2006). One large retrospective study found no statistically significant difference in outcome between wet and dry ears with the use of cartilage as the grafting material (Dornhoffer 2003). While the influence of inhalant allergy on the success of tympanoplasty has not been systematically studied in the literature, there is reason to believe that failure to identify and treat symptomatic patients may potentially affect the outcome of surgery in certain cases. All patients are queried about symptoms related to inhalant allergy and in vitro testing is conducted in selected adult patients and older children. Attempting to establish guidelines for surgical intervention, based on the aforementioned factors, would be a daunting task given the heterogeneity in the design and execution of the various studies reported in the literature. The type of repair, specific grafting material used, age group cohorts, length of follow-up, and outcomemeasures all differ considerably among these studies. Ultimately, the decision to repair a tympanic membrane perforation, and the technique used to do so, is based on those factors that an experienced surgeon may consider potentially influential in the likelihood of success in an individual patient. The following clinical situations are cause for hesitation, but do not necessarily indicate that surgery should be delayed:

  • Children less than 4 years of age
  • Evidence of poor eustachian tube function in the contralateral Ear (e.g., Tympanic membrane perforation or retraction, persistent otorrhea, effusion)
  • A chronically draining ear with suspicion for chronic inflammatory disease in the epitympanum and mastoid cavity and/or presence of cholesteatoma and complimentary findings on computed tomography
  • Previous history of failed tympanolasty

A 3-year-old patient with a dry central perforation and a normal contralateral ear and no history of recurrent otitis media in the contralateral ear, may be considered for tympanoplasty surgery. The potential effect of unilateral mild to moderate conductive hearing loss on speech and language development and the ability to participate in water activities (learning to swim) are valid concerns of parents. Nevertheless, it would be only under the most optimal conditions that a child under 4 years of age would be considered for surgery. With regard to high risk patients (situations 2–4), if closure of a tympanic membrane perforation is performed in conjunction with surgery for chronic ear disease and there is evidence of delayed healing, retraction, or effusion on follow-up examination, a tympanostomy tube may be placed at 6–8 weeks postoperatively. This rational approach would provide the patient with an opportunity toward establishing a healthy, well-ventilated ear and a means for, at least, partially restoring the hearing mechanism.

Tympanoplasty Technique: Advantages and Disadvantages

Underlay Technique

Advantages
  1. Avoids blunting and lateralization
  2. Less mobilization of the tympanic membrane
  3. Tympanic membrane heals at the correct level
  4. Thinner neomembrane
  5. Anterior graft support via anterior suspension
Disadvantages
  1. Reduced depth of the middle ear space
  2. Development of adhesions between graft and cochlear promontory
  3. Difficulty suspending graft if the anterior fibrous annulus is torn

Overlay Technique

Advantages
  1. Wide exposure of the anterior tympanomeatal angle
  2. Reduced risk of blunting of the anterior angle with the annular”tuck-in” method
  3. Maintains the preoperative depth of the middle ear space
Disadvantages
  1. Blunting of the anterior tympanomeatal angle
  2. Graft lateralization
  3. Medial canal fibrosis
  4. Delayed healing
  5. Epithelial pearls
  6. Thickened neomembrane

Pitfalls of Tympanoplasty

  1. Failure to remove shredded pieces of epithelium from the tympanic membrane remnant and/or failure to unfurl the folded edges of the canal skin flaps may lead to epithelial pearl formation or canal cholesteatoma.
  2. Avoid overheating the canal bone while drilling by using continuous copious irrigation. Excessive overheating is particularly troublesome when using a diamond burr and may predispose to osteocyte cell death and obliteration of the microvascular supply to thecanalboneandoverlyingfascia graftandcanal skin.
  3. Avoid exposure of the temporomandibular joint capsule while drilling the anterior canal wall. Dehiscences measuring greater than 4 mm should be considered for reconstruction with tragal cartilage. Temporomandibular joint capsule exposure may lead to pain with mastication and/or development of granulation tissue at the site of the dehiscence.
  4. The techniques described in this section for the underlay and overlay repair require extensive mobilization of canal skin and considerable bone removal, both of which may predispose to delayed healing.
  5. Failure to remove squamous epithelium over the tympanic membrane remnant for overlay grafting may lead to epithelial pearl formation. This can often be managed in the clinic by marsupializing the lesion and removing the squamous debris.
  6. Avoid excessive deposition of bone dust in the middle ear space. It is essential that any bone dust that collects in the vicinity of the oval or round window be irrigated and removed to avoid the potential for ossicular fixation or round window niche obliteration.

References

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