Chapter 2 Confusion has existed for many years regarding the nomenclature used to describe surgery on the tympanic membrane (TM), middle ear, and ossicular chain. Wullstein’s classic classification system (types I–V) was based on the relative position of the TM to the other middle ear structures including the ossicles and inner ear membranes.1 This description was developed prior to the introduction of many of the procedures and prostheses that are used so commonly today in middle ear surgery, so its ability to adequately describe current surgical techniques is limited. Consequently, the term tympanoplasty by itself is not adequately descriptive, simply indicating some sort of reconstructive surgery on the TM or middle ear. It is therefore necessary for the surgeon to use further descriptive terms in addition to the term tympanoplasty to communicate effectively which procedures are being described. The term myringoplasty refers to reconstructive surgery that is limited to the TM. It was actually introduced by Berthold, who successfully closed a TM perforation using a full thickness skin graft in 1878.2,3 He was the first to report the use of autologous tissue in an effort to repair the TM; prior to that, several different artificial or animal-based materials were used dating back to as early as 1640.4 By definition, any manipulation of the ossicular chain is beyond the scope of a pure myringoplasty. Because the term tympanoplasty includes surgery on both the TM and middle ear, however, many cases of myringoplasty are labeled tympanoplasty by surgeons, further adding to the confusion. The terms myringoplasty and tympanoplasty without ossicular reconstruction are synonyms unless other manipulation of the middle ear such as removal of cholesteatoma is included in the tympanoplasty procedure. Within the more limited surgery of the TM, many different approaches to myringoplasty have been described. Patients with perforations of the TM may present acutely or with symptoms suggestive of a chronic perforation. Acute perforations are usually the result of acute otitis media with rupture of the TM due to increased pressure in the middle ear, trauma to the ear canal or temporal bone, or sudden pressure changes transmitted to the TM. The majority of cases of acute otitis media resolve spontaneously with or without medical treatment and without any significant injury to the TM. Certain infections, however, build up sufficient pressure within the middle ear space, which is effectively closed due to eustachian tube blockage, that the flexible TM ruptures, thereby relieving this pressure. This acute event is associated with sudden drainage from the ear that is often both bloody and purulent, and also with an increase in pain followed by a marked diminution of pain. This rupture of the TM effectively releases the infection from out of the skull and away from other fragile and vital structures such as the central nervous system (CNS) and the inner ear. Most cases of acute TM perforations due to infection will heal without surgical treatment over a period from a few days to a few weeks. Resolution of the infection is an important consideration as to whether this healing will occur because a perforation is more likely to remain open if the drainage persists. Treatment of such infections with both systemic antibiotics and aural antibiotic drops is highly recommended. Although not proven, it is believed that thin, atelectatic TMs are more likely to rupture and less likely to heal without surgery than normal membranes. Trauma can produce a tear in the TM either directly, such as a penetrating injury, or indirectly, such as from a shearing movement in bone as seen in a temporal bone fracture. Although any small object could produce a penetrating injury, the cotton-tipped swab is a particularly common offender, because it is used in an attempt to clean or scratch the ear canal and too often finds its way through the TM. These perforations are typically central in location and can be quite large. A discussion of the possible trauma to the ossicles and inner ear is beyond the scope of this chapter, but the perforation will be accompanied by a moderate amount of self-limited bleeding and sudden pain. Temporal bone fractures may present with hemotympanum when the TM is intact or with a perforation and bleeding when the annulus or TM is torn. Longitudinal fractures are particularly prone to tearing the TM, but mixed or transverse fractures may also present in this manner. Significant changes in pressure in the outer ear may also produce ruptures of the TM. This can be negative pressure, as is seen in injuries that occur while flying in which the cabin pressure is not maintained adequately, or positive pressure such as a slap with a cupped hand to the ear canal, resulting in pushing on the TM. Again, a sudden onset of pain and bleeding accompanied by some degree of hearing loss are usually present. The pain and bleeding usually resolve quickly without treatment, and unless infection develops, no otorrhea occurs and the patient is asymptomatic with the exception of a hearing loss. Patients with a chronic perforation of the TM usually present with a conductive hearing loss, otorrhea, or both. Nearly all patients with a chronic perforation of their TM have otorrhea to some degree. There is a wide spectrum of the severity of this symptom. Some patients are not able to recall ever having an episode of drainage, whereas other patients have constant drainage of malodorous, discolored material that drains into their conchal bowl, onto their ear lobe, and even onto their upper neck on a daily basis. Between these two extremes, most patients have intermittent drainage that may occur spontaneously or be brought on by getting water in the ear or suffering from an upper respiratory infection. These infections are typically caused by multiple microorganisms, particularly Pseudomonas, Staphylococcus, Proteus, and various anaerobic bacteria. They are frequently resistant to most orally administered antibiotics presumably due to the repeated courses of antibiotics that have been used to treat this condition over the period of the existence of the perforation. Patients with a chronic TM perforation generally present with a conductive hearing loss. The degree of hearing loss varies significantly among patients, from no detectable loss up to a moderate conductive loss. Among the factors influencing the degree of hearing loss present are the size and location of the perforation, the presence of otorrhea, and the status of the ossicular chain. Other chapters of this book address details of ossicular absence, erosion, or fixation, but with an intact ossicular chain the conductive hearing loss associated with a TM perforation rarely exceeds 35 dB, regardless of the size or location of the hole. Small perforations may be associated with no significant impairment of hearing. Generally speaking, the larger the perforation, the greater the degree of hearing loss. Initially the conductive hearing impairment affects only the very low frequencies, but as the size of the perforation increases, the hearing loss increases and involves more of the middle frequencies.5 Anterior perforations tend to produce smaller hearing losses than their posterior counterparts, presumably due to the exposure of the round window to the effect of sound waves penetrating directly through the perforation and striking the round directly setting up a competing fluid wave within the inner ear. Even large anterior perforations rarely produce greater than 15 dB of conductive hearing loss in the absence of infection or ossicular involvement. In addition to the effect of the exposing the round window directly to the sound waves, perforations also produce hearing loss by diminishing the surface area of the TM available to collect the energy in the form of sound waves and then transmit that energy onto the inner ear via the ossicular chain. It is therefore understandable that larger perforations produce a greater degree of hearing impairment. For a patient presenting with a perforation of the TM, the physician should take a thorough history and perform a physical examination. The history should attempt to determine if the perforation is acute or chronic and what if any event precipitated the perforation. Because most acute perforations heal spontaneously with proper medical treatment, determining when the perforation developed is a prime consideration. Ears with acute perforations should be cleaned and examined carefully under a microscope. If edges of the perforation can be seen to be deflected medially into the middle ear, it is desirable to elevate them gently with a suction to prevent squamous epithelium from growing in the middle ear. It is neither necessary nor desirable to treat these acute perforations with antibiotic ear-drops, as many of the currently available drops contain materials that may be ototoxic when exposed to the round window. It is indeed desirable to prevent infection, so these patients are advised to keep all water out of their ears and watch for any signs or symptoms that would suggest infection. When infection does occur, treating it aggressively will increase the likelihood that spontaneous healing will occur.
MYRINGOPLASTY
PATIENT PRESENTATION
AUDIOLOGIC CONSIDERATIONS
PREOPERATIVE ASSESSMENT
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