Chapter 4 The modern era of tympanoplasty began in the 1950s with the work of Zollner1 and Wullstein2 using full-and split-thickness skin grafts to repair the tympanic membrane (TM). Subsequent innovations included the use of other grafting material including canal skin, vein, perichondrium, and temporalis fascia.3–5 Modern approaches to tympanoplasty differ in whether the graft is placed lateral or medial to the TM remnant.6–10 This chapter describes lateral grafting or overlay tympanoplasty techniques. The advantages of lateral grafting techniques are: 1. High success rate. There was a 97% success rate in closure of the perforation in a review of the experience at the House Ear Clinic of over 1700 cases of overlay tympanoplasty.11 2. Excellent intraoperative and postoperative visualization of the anterior meatal angle. This is especially helpful in cases of anterior perforation with a large anterior canal wall bony overhang. 3. Preservation of the middle ear space. Because the graft is placed lateral to the drum remnant, the middle ear space is less likely to be reduced by overlay tympanoplasty. The disadvantages of lateral grafting are: 1. The potential for lateralization of the graft or blunting of the anterior meatal recess if proper surgical techniques are not carefully applied. This occurs more commonly in cases where the surgeon is inexperienced with the procedure. 2. Squamous epidermal inclusion cysts may de-velop if the TM epithelium is not completely removed prior to grafting. These cysts may also occur along the external auditory canal. In either case, they are generally easily treated with simple unroofing and marsupialization in the office. 3. Relative to underlay tympanoplasty, healing from overlay techniques takes longer, lasting up to 4 to 6 weeks. Patients with chronic otitis media usually present with recurrent or persistent otorrhea or with hearing impairment. Patients with a central perforation of the TM without cholesteatoma usually describe recurrent episodes of otorrhea that resolve promptly with topical treatment. Persistent malodorous discharge most commonly reflects advanced middle ear and mastoid disease, often in association with a cholesteatoma. The degree of hearing impairment depends on several factors including the size and location of the perforation, the extent and duration of middle ear mucosal disease, and the status of the ossicles. Rarely, a patient with advanced disease including cholesteatoma may present with pain, vertigo, facial paralysis, or central nervous system (CNS) complications of otitis media. The goals of surgery in chronic otitis media are to produce a dry, safe ear; to restore hearing; and to preserve normal anatomic structures and contours when possible. Careful evaluation of the patient is necessary to determine the necessity and urgency of surgery. In patients with a unilateral dry, central perforation and minimal hearing loss, the main indication for surgery is to prevent further episodes of otorrhea, and surgery is elective. Patients with advanced mucosal disease or cholesteatoma usually require surgical intervention to eradicate infection and produce a safe ear. Successful and safe tympanoplasty demands careful preoperative examination of the patient. The preoperative examination alerts the surgeon to potential complications of the disease process that may be encountered in surgery and to predict the outcome of surgery. This is helpful, not only in planning the surgical procedure, but also in advising patients about realistic postoperative expectations and alerting them to potential complications. Examination of the TM is best performed with a microscope. Cleaning of any debris or discharge in the external canal allows visualization of the entire TM. Specific notes are made regarding the type of perforation, the character of the discharge, and the status of the middle ear mucosa and ossicles. In general, perforations can be divided into central or marginal. Central perforations maintain a margin of drum remnant around the circumference of the perforation. Typically, these perforations only intermittently drain and are not associated with cholesteatoma. Marginal perforations involve the periphery of the TM. They are most often located in the posterior-superior quadrant or in the pars flaccida; present with persistent, malodorous discharge; and frequently involve cholesteatoma. Deep retraction pockets and cholesteatoma usually involve the pars flaccida or the posterior-superior quadrant of the pars tensa. Occasionally a polyp or granulation tissue may prevent inspection of the retraction pocket or cholesteatoma. Not infrequently deep retractions in the pars flaccida extend into the attic and even the mastoid without significant ossicular involvement. These patients may have a normal-appearing pars tensa, minimal hearing loss, and no otorrhea, highlighting the importance of careful inspection of the entire TM with an operating microscope prior to tympanoplasty. Often the status of the middle ear mucosa and ossicular chain can be evaluated by careful examination through the perforation. A normal or near-normal mucosa predicts a favorable outcome. Likewise, an intact ossicular chain improves the prognosis for hearing improvement. Tympanosclerosis, a hyaline degeneration in the middle ear, is frequently seen in ears with chronic otitis media. Although tympanosclerosis rarely affects the success of the TM graft, it may contribute to ossicular fixation. Stape-dial fixation by tympanosclerosis, although rare, requires a second operation. Ossicular erosion or necrosis usually involves the incus. The status of the stapes can often be determined and is the most important ossicular variable in hearing improvement. A pneumatic otoscope is used to compress and rarefy the air of the external ear canal. When a labyrinthine fistula is present, the patient often complains of vertigo, and nystagmus is present. A negative fistula test, however, does not exclude a fistula, a point that should be kept in mind during surgery. Pneumatic otoscopy also helps determine the mobility of the remnant of the par tensa or the presence of a perforation that is difficult to see. Preoperative air and bone pure tone thresholds and speech discrimination scores should be performed on every patient undergoing tympanoplasty. This information not only helps the surgeon predict the potential for hearing improvement, but also may alert the surgeon to potential complications of chronic otitis media such as labyrinthine fistula. Audiometric results are confirmed with tuning fork testing. We do not routinely test the function of the eustachian tube prior to tympanoplasty. A careful history and physical examination predict outcome more accurately than any test of the eustachian tube. Likewise, we do not routinely order radiographic studies in patients with chronic otitis media. If a patient has a complication of the disease such as labyrinthine fistula or facial nerve weakness, or in selected revision cases, the temporal bone is imaged with high-resolution computed tomography.
OVERLAY TYMPANOPLASTY
PATIENT PRESENTATION
INDICATIONS FOR SURGERY
PREOPERATIVE EVALUATION
EXAMINATION
PERFORATION
RETRACTION POCKETS/CHOLESTEATOMA
MIDDLE EAR/OSSICULAR STATUS
PNEUMATIC OTOSCOPY/FISTULA
AUDIOLOGY
EUSTACHIAN TUBE FUNCTION TESTING
RADIOLOGY
OPERATING ROOM SETUP AND PATIENT
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