Tympanoplasty—Undersurface Graft Technique: Postauricular Approach

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Since the fundamental principles of tympanoplasty were introduced by Wullstein and Zollner, there has been great diversity in the accepted surgical techniques used for repair of the tympanic membrane. The multitude of graft materials employed is a testimony to the difficulty of middle ear reconstruction. With advanced microsurgical techniques, the state of the art has now developed to the extent that graft success rates of 90% to 97% are expected. Two basic grafting techniques have evolved based on where the graft material is placed in relation to the drum remnant (overlay vs. underlay techniques). This chapter presents a method of undersurface grafting. The detailed surgical techniques and appropriate preoperative and postoperative care are presented.

Historical Aspects

Modern middle ear reconstructive surgery represents the culmination of more than a century of contributions by numerous dedicated and innovative otologic surgeons. The term tympanoplasty was originally defined in 1964 by what was then the American Academy of Ophthalmology and Otolaryngology’s Committee on Conservation of Hearing as “an operation to eradicate disease in the middle ear and to reconstruct the hearing mechanism without mastoid surgery, with or without tympanic membrane grafting.” If a mastoid procedure is included, the term tympanoplasty with mastoidectomy is used.

The era of surgical repair of the tympanic membrane dates as far back as the 19th century. In 1853, Toynbee described the closure of a perforation of the tympanic membrane using a small rubber disk attached to a silver wire. Ten years later, Yearsley advocated placing a cotton ball over the perforation; in 1887, Blake introduced the concept of placing a thin paper patch over the membrane. In 1876, Roosa introduced the use of cautery to promote spontaneous healing of tympanic membrane perforations ; he used silver nitrate. Later, Joynt, Linn, and Derlacki described modifications of this technique using various forms of cautery and patches. However, the closure of tympanic membrane perforations was considered appropriate only for dry central perforations. At this point, no one advocated the use of drum closure for the chronically draining ear.

It was not until 1952 that Wullstein and Zollner revolutionized middle ear surgery by advocating reconstructive grafting of the chronically diseased ear through the use of full- or split-thickness skin grafts. House and Sheehy and Plester later used canal skin, believing that it more closely resembled the squamous layer of the tympanic membrane. The overall poor success rates of these grafts and the development of iatrogenic cholesteatomas prompted the search for alternative grafting materials.

Shea and Tabb, working independently, described the use of an autogenous vein to close the tympanic membrane. Goodhill advocated the tragal perichondrium in the mid-1960s, and tympanic membrane homografts became popular a few years later. Glasscock and House reported the first sizable series of homograft tympanic membrane transplants in 1968. Interest in homografts has waned, however, largely because of the fear of transmission of infectious diseases. Storrs performed the first fascia graft in the United States. Although vein, perichondrium, and homografts still have their advocates, autogenous fascia has now become the standard by which all other grafting materials are measured.

Skin graft repairs require laying the graft on top of the denuded drum remnant to repair the tympanic membrane perforation. This method of repair eventually became known as the overlay technique and was carried over to the other forms of grafting material. With the use of connective tissue grafts, the graft material could be placed medial to the tympanic membrane remnant. The success of this approach eventually gave rise to the underlay technique of tympanic membrane grafting; Austin and Shea reported a large series. The proponents of the underlay procedure submit that it eliminates many of the problems associated with overlay grafts, such as anterior blunting, epithelial pearl formation, and lateralization of the new drum.

In 1973, Glasscock described an underlay grafting technique that relied on a postauricular approach. With minor modifications, this approach remains the preferred method of dealing with disorders of the tympanic membrane and the middle ear.

Preoperative Fundamental Principles

Regardless of the grafting technique chosen, the preoperative evaluation and management of a patient with a tympanic membrane perforation remain the same. A complete clinical history is obtained and a comprehensive head and neck examination performed. Otoscopic examination is performed with the aid of an operating microscope if necessary. All findings are diagrammed on the patient’s chart. All patients receive a pure-tone air-bone conduction audiogram along with speech discrimination testing. Tuning fork tests should be performed on all patients to confirm the audiological findings. Particular attention is addressed to the nasopharynx if there is evidence that nasopharyngeal and/or sinonasal pathology is resulting in secondary eustachian tube dysfunction.

Traditional Objectives

As with any surgical procedure, successful outcomes result from mastery of understanding and execution of each component of the process as a whole. It is useful to distill the task of tympanoplasty into its important fundamentals.

The traditional objectives of tympanoplasty have not changed in 50 years and remain:

Eradication of disease
Closure of the ear by grafting
Hearing rehabilitation

The goals, in this order of priority, allow for patient counseling and reasonable expectations.

Predisposing Conditions

Tympanoplasty is usually successful in achieving the above-listed goals in the short term. To ensure long-term success, the conditions predisposing to failure must be managed prospectively. Generally, the status of the upper respiratory tract influences the eustachian tube function and, consequently, the long-term success of tympanoplasty.

Adenoidal Hypertrophy and Adenoidectomy

Excessive adenoidal hypertrophy is regarded, by consensus, to influence the success of tympanic membrane grafting. Adenoidectomy should be performed prospectively. It is generally not advised to perform adenoidectomy, with its significant effects on the nasopharynx in the short term, simultaneously with tympanic membrane grafting. After the adenoidectomy, the tympanic membrane grafting is scheduled as a separate procedure, approximately 4 weeks later. Tonsillectomy is performed as an independently indicated consideration. Its effect on tympanoplasty is negligible. The clinical setting in which this occurs is generally in children younger than 10 years.

Nasal or Sinus Condition

Similar to nasopharyngeal disease, significant nasal septal deformity, polyposis, or acute sinusitis should be managed before grafting an ear. Acute sinusitis would warrant cancellation of tympanoplasty. Lesser degrees of nasal obstruction or chronic sinusitis are addressed as logically dictated by the clinical circumstances before or at some time after tympanoplasty.

Allergy

Allergic disease is an inexorable detriment to the long-term success of tympanic membrane grafting. In endemic areas, it should not be disregarded. At some time in the perioperative period, the tympanoplasty patient is referred for comprehensive allergy diagnosis and management. Immunotherapy, when indicated, may influence the long-term outcomes. Acute exacerbations, often seasonal, are managed pharmacologically with antihistamines and nasal steroids.

Rare Disorders

Particularly in recidivistic disease, the presence of rare associated diseases must be kept in mind. Such rare diseases include tuberculosis, sarcoidosis, diabetes mellitus, hematologic disorders, histiocytosis, immunodeficiency syndromes, and, in recurrent adult disease, neoplasms should not be disregarded.

Preoperative Preparation

Otorrhea

Every attempt is made to operate on dry ears. Preoperative infection control in the involved ear is useful, but not essential. At the initial evaluation, the draining ear is otomicroscopically evacuated. Instructions are given to initiate the instillation of steroid-containing antibiotic drops for a period of 7 to 14 days prior to the date of operation. A cost-effective alternative to ototopical antibiotics include irrigating the ear with sterile 1.5% acetic acid solution, which can be especially helpful in eradicating recalcitrant infections. The instillation of drops in the infected ear affords minimal ototoxicity risk. A complicated or systemic infection may warrant oral antibiotics. In the absence of any immunocompromising accompaniment, cultures are not routinely performed. The physician must be vigilant for signs and symptoms of intratemporal or extratemporal complications. Surgery is scheduled, and the ear is operated on, draining or not, following all best attempts at resolving preoperative otorrhea.

Eustachian Tubal Tests

No “gold standard” clinical test exists for eustachian tubal physiology. Eustachian tubal patency is testable via methods such as the Valsalva maneuver and the Toynbee test, but it is not important in the grand schematic of tympanoplasty. Eustachian tubal physiology tests exist (e.g., the Flisberg test), but are clinically impractical and are not performed. A statement attributed to Sheehy is true: “Sometimes the best test of eustachian tubal function is a tympanoplasty.”

Eustachian tube function is important to tympanic membrane grafting success. The status of the contralateral ear often predicts the eustachian tubal capacity of the involved ear. Apparent current eustachian tubal dysfunction may be a consequence of active infections unilaterally or the aftermath of a lifetime of chronic otitis media. Tympanoplasty is not contraindicated, but the surgeon must counsel the patient accordingly regarding the role of eustachian tube dysfunction in the repair prognosis. Postoperatively, when the ear is restored to a more normal state, its eustachian tubal function may also be restored. In the difficult situation of tracheostomy in which the eustachian tube function is compromised or when effusion or retraction affects the successful graft, the ear can be ventilated in the office. Tube placement can be performed in the first month after the procedure in the office because the tympanic membrane is still anesthetized.

An atelectatic ear should not preclude tympanoplasty. Rather, it is an indication for cartilage tympanoplasty.

Imaging

The imaging standard for chronic otitis media is now high-resolution temporal bone computed tomography (CT). A contrast medium is also employed to evaluate clinically silent epidural, intracranial, or lateral sinus abscess. All ears for grafting are not imaged. Only hearing ears and disease in long-standing adult chronic otitis media are ideal candidates. It is especially helpful to obtain CT scans for revision surgery, particularly if another surgeon performed the initial surgery. Selected cholesteatomas may be studied, although imaging is not necessary for all cholesteatomas. Patients with a cholesteatoma in which an inner ear fistula or tegmen defect with encephalocele is suspected are good candidates for imaging. The current state of magnetic resonance imaging (MRI) precludes its routine use in ear imaging of chronic otitis media. Magnetic resonance angiography is useful in the venous phase to assess the lateral venous sinus.

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