Middle Ear, Tympanic Membrane, Perforations

Frequency

Incidence of tympanic membrane perforation (TMP) in the general population is unknown. One survey found that that 4% of a population of Native American children had TMP.[7] Another study found that 3% of children treated with ventilation tubes had the condition.[8] However, the incidence in the general population has not been studied. Even the exact number of surgical TMP repairs performed each year is unknown. Analysis of government statistics indicates that perhaps 150,000 tympanoplasties are performed per year in a population of 280 million.

Infection is the principal cause of tympanic membrane perforation (TMP). Acute infection of the middle ear may cause a relative ischemia in the drum concurrent with increased pressure in the middle ear space. This leads to a tear or rupture of the eardrum that is usually preceded by severe pain. If the perforation does not heal, it leaves a residual TMP.

A prominent school of thought now advocates less aggressive use of antibiotics. Those who hold this position recognize that many episodes of otitis media are caused by viruses, so they resolve spontaneously; advocates of this position desire to slow emergence of antibiotic-resistant bacterial strains. Evidence is emerging that an increased incidence of acute mastoiditis is resulting from reduced use of antibiotics.[9]  It remains to be seen whether increased incidence of perforation and other complications of otitis media, such as brain abscess, meningitis, and septic sigmoid sinus thrombosis, also occur.

A prospective study by Marchisio et al. indicated that an association exists between recurrent episodes of acute otitis media (AOM) and an increased risk for the development of spontaneous tympanic membrane perforation. The study involved 177 children with AOM complicated within 12 hours by spontaneous tympanic membrane perforation. Within that group, recurrent spontaneous tympanic membrane perforation occurred in 92% of those with recurrent AOM and in only 16.9% of those without recurrent AOM. The most common pathogen detected in the middle ear fluid of the study’s children was nontypeable Haemophilus influenzae.[10]  Ear canal infections rarely cause TMP. When this occurs, it is often associated with infection by Aspergillus niger.

Traumatic perforations may result from blows to the ear (eg, being struck with the flat of the hand; falling from water skis with the head hitting the water surface, ear down).[11] Exposure to severe atmospheric overpressure from an explosion can tear the drum.[12] TMP from water pressure occurs in scuba divers, usually in a drum with atrophy from previous disease. Objects used to clean the ear canal can perforate the drum (ie, cotton swab trauma).

Inexpertly performed irrigation of the ear canal for wax can lead to perforation. In some settings, when irrigation for cerumen is relegated to medical assistants, otolaryngologists may see 10-20 patients per year with this injury. Evidence exists that such perforations are less likely to heal spontaneously.[13]

TMP is intentionally created whenever a surgeon makes an incision in the eardrum (myringotomy). When pressure-equalizing tubes (ventilating tubes) are placed, the TMP purposely is held open. Failure of surgically created openings to heal when the tube extrudes results in chronic TMP. Roughly 1% of patients who undergo a myringotomy with ventilation tube insertion will develop a chronic perforation.[14] In some patients with chronic eustachian tube dysfunction, however, the presence of a dry, chronic perforation may actually be helpful for ventilation. 

Many tympanic membrane perforations resolve spontaneously. At times, a perforation heals with a thin membrane consisting only of mucosal and squamous epithelial layers, without a fibrous middle layer. Such a neomembrane may be so thin that it is mistaken for an existing perforation instead of a healed one.[15] Neomembranes may retract deeply into the middle ear, sometimes making them more difficult to distinguish from actual perforations, particularly in the setting of coexisting ventilation issues and negative middle ear pressure. Examination under the operating microscope resolves ambiguity and is recommended. Deep retraction, especially in the posterior-superior quadrant of the drum, may cause erosion of the ossicles or precede cholesteatoma formation.

If bacteria-contaminated water enters the ear canal, the presence of a perforation renders the ear more susceptible to infection. Water precautions are therefore recommended, particularly for large perforations, including the use of earplugs while swimming and avoidance of submerging the head in water when possible. Water surface tension may protect the ear from penetration through a very small perforation. The presence or history of perforation is an absolute contraindication to irrigation for cerumen removal. For patients who have undergone a myringotomy and ventilation tube insertion, consensus guidelines recommend that water precautions not be routinely used, given the limited proven benefit.[16]

A study by Park et al indicated that perforation size and pneumatization of the middle ear and mastoid affect the degree of conductive hearing loss in cases of tympanic membrane perforation. The study involved 42 patients who underwent tympanoplasty type I, or myringoplasty, with a greater preoperative mean air-bone gap (ABG) found in association with larger perforation size and with a smaller middle ear and mastoid pneumatization volume.[17]  A prospective study by Pusz and Robitschek reported that subacutely, patients in the study who suffered a tympanic membrane perforation from a combat-related blast injury had both conductive and sensorineural hearing loss, with the latter making up 49% of the loss.[18]

The conductive hearing loss resulting from a TMP appears to be greater at lower frequencies. It increases as the perforation size grows and the volume of the middle-ear and mastoid air space decreases but does not change with location.[19, 20]

Many persons live their lives with tympanic membrane perforations (TMPs) that are entirely without symptoms; they may even benefit from a perforation if they have significant, coexisting eustachian tube dysfunction and poor ventilation. Repair of such lesions is usually not indicated. Perforations may be associated with recurrent infection when exposed to water. In swimmers, divers, and other water sports enthusiasts, repair may be indicated as a quality-of-life issue. Hearing loss may be present, especially with larger perforations, and may be a reason for repair.[21] Because a risk to residual hearing exists with every operation on the ear drum, a risk-benefit analysis in which the patient participates is mandatory.[22] For example, question whether the person may be helped just as much with use of a hearing aid.

The tympanic membrane, also called the eardrum (or just the drum), is a stiff (but flexible), translucent, diaphragmlike structure. The eardrum moves synchronously in response to variations in air pressure, which constitute sound waves. The drum's vibrations are transmitted through the ossicular chain to the cochlea. In the cochlea, vibratory mechanical energy changes to electrochemical energy and streams via the eighth cranial nerve to the brain. The tympanic membrane and its attached ossicles thus act as a transducer, changing one form of energy into another form. (See the image below.) The biomechanical coupling of this conductive system produces a gain that can help to overcome the impedance mismatch as the energy undergoes a phase shift from air to the liquid of the inner ear.

The tympanic membrane has two distinct zones. The larger of the two zones is the pars tensa. This zone consists of a tough and resilient fibrous layer with a diaphanous mucosal layer inside and squamous epithelium outside. The smaller zone is the pars flaccida, which lies superior to the suspensory ligaments of the malleus and lacks a fibrous layer.

Tympanic membrane perforation (TMP) may be unilateral or bilateral. Select the worse-hearing ear first when performing bilateral TMP repair. If increased hearing loss complications ensue, the better-hearing ear remains uninjured. For the same reason, if the TMP is present in a patient's single hearing-capable ear, a frank discussion must be had with the patient regarding the risk of further hearing loss.

Radiography and MRI are of no value unless the clinical picture suggests ossicular destruction and/or cholesteatoma. Asymptomatic perforations, especially if hearing is near normal, require no imaging studies.

See the list below:

• Most tympanic membrane perforations (TMPs) are diagnosed using routine otoscopy.

• Small perforations may require otomicroscopy for identification.

• Some hearing screening programs include middle ear impedance testing.

• Screening tympanometry may reveal abnormalities consistent with perforation. Confirmation still requires examination.

• Always perform audiometry upon initial TMP diagnosis and again before any repair attempt, whether in the office or in the operating room.

  • Preoperative and postoperative audiography should always be performed. A major conductive loss not only alerts the surgeon to the possible existence of ossicular lesions, but documentation of a preexisting sensorineural hearing loss may protect the surgeon from later allegations that the surgery caused the hearing loss.

  • Audiometry often reveals normal hearing. The presence of mild conductive hearing loss is consistent with perforation, and a conductive component of at least 30 dB indicates possible ossicular discontinuity or a pathologic condition.

Medical therapy for perforations is directed at controlling otorrhea. Take into account ototoxicity risk from topically applied eardrops when treating ear infections concurrent with tympanic membrane perforation (TMP). Infection alone occasionally can cause sensorineural hearing loss. Clinical toxicity from eardrops in the presence of ear infection has not been demonstrated unequivocally, although experiments in animals clearly demonstrate a correlation. Legal implications of administration of ototoxic eardrops preceding sensorineural hearing loss are clear. For this reason, avoid eardrops containing gentamicin, neomycin sulfate, or tobramycin in the presence of TMP. Avoiding contamination of the middle ear space with water via the TMP is critical in minimizing otorrhea from a perforation.

A retrospective study of patients with traumatic TMP greater than one quarter the size of the membrane found that topical application of either epidermal growth factor (EGF) or ofloxacin otic drops reduced healing time over that associated with observation. Healing with EGF and ofloxacin otic drops took a mean 12.6 and 12.9 days, respectively, compared with 35.7 days for observation. The actual closure rates for the three treatment methods, however, did not differ significantly.[23]

Systemic antibiotics are generally not needed when controlling otorrhea from a TMP, given the ease with which topical antibiotics can be administered.

Treatment of tympanic membrane perforation (TMP) falls into three categories. No treatment is necessary for nonswimming patients with minimal hearing loss and no history of recurrent ear infection. A hearing aid may prove the only necessary treatment for patients with symptomatic hearing loss but no infection or swimming history. Two options exist for patients who are not in either category.

Office treatments

The first option is to perform one of the available office treatments. Such treatments have the best chance of working when the perforation is small and involves neither the umbo nor the annulus. Several methods apply.

The simplest, but least effective, method is to freshen the edges of the perforation and then apply a small patch of cigarette paper, providing a scaffold for regrowth. This technique was developed in the 1800s; it presumably remains in the repertoire because it sometimes works. Mechanical stripping of the perforation margin (with topical anesthetic or without) before applying the patch slightly increases the success rate.

A fat-plug tympanoplasty can also be performed, by obtaining a small plug of fat from the postauricular sulcus or earlobe with the patient under local or general anesthesia. Prepare the TMP by anesthetizing its margins with carefully applied phenol solution. Next, mechanically debride the edges with microcup forceps. The fat is then tucked into the perforation, extending into the canal and into the middle ear space.

The paper-patch method has a reported success rate of 67%; the fat-plug tympanoplasty, of 87%.[24]

Niklasson and Tano studied the use of a Gelfoam plug in combination with surgical removal of the perforation edges. They concluded that although additional comparative studies are recommended, the plug seems to result in about the same closure rate as the fat plug technique in persistent small ear drum perforations.[25]

Other recently reported forms of office treatment use fibrin glue or a patch composed of a hyaluronic acid ester and a dressing component. The use of basic fibroblast growth factor with a proprietary patch that consists of a silicone layer and atelocollagen has been described. Excellent success has been reported, but with very small numbers of patients. 

Tympanoplasty

The second option is to perform tympanoplasty with the patient under local or general anesthesia. An incision may be made behind the ear or entirely through the ear canal, depending on the location and size of the tympanic membrane perforation (TMP). Repair requires preparation of a suitable bed for placement of a graft. By far, the most commonly used grafting material is temporalis fascia. Allograft tympanic membranes obtained from cadavers, once abandoned because of fear of transmitting viral pathogens, are again being used. Grafts may be placed medially or laterally to the perforation, or in a combined position.[6] Surgeon preference plays a part in these decisions and in decisions concerning the technical problems associated with size and location of the perforation and the shape, angle, and bore of the ear canal.

Tympanoplasty successfully closes the TMP in 90-95% of patients. Fortunately, second and third operations succeed in more than 90% of the remaining patients. Consequently, fewer than 1 per 1000 persons still has TMP after 3 operations.

A retrospective study by Carr et al indicated that in adults undergoing myringoplasty (type 1 tympanoplasty), the perforation site affects the success of the procedure, with the closure rate significantly reduced for anterior and subtotal perforations. In the study’s pediatric patients, however, the perforation site appeared to have no such affect.[26]

A study by Tseng et al reported successful subjective and objective outcomes in tympanic perforation repair with endoscopic transcanal myringoplasty. Graft success was achieved by 3 months postoperatively in 87.9% of ears, with the air-bone gap closed to within 20 dB in 86.8% of ears. Pain medication was used for a mean duration of 2.0 days, with the mean pain scale score determined to be 0.1 on the third postoperative day.[27]

A retrospective study by Larrosa et al indicated that in the transcanal, endoscopic repair of subtotal TMPs in adults, results from the use of palisade cartilage grafts are comparable to those from employment of the one-piece composite cartilage-perichondrium technique, with closure rates of 85% and 86.3%, respectively. Hearing improvement was also similar with both techniques.[28]

A study by Cass et al indicated that in primary pediatric tympanoplasty, healing rates with non-autologous collagen grafts are equivalent to those with autologous tissue grafts.[29]

Inlay, underlay, and overlay surgery

A study by Haksever et al found that inlay butterfly transcanal cartilage tympanoplasty compared favorably with conventional underlay tympanoplasty in patients with dry, perforated chronic otitis media. The investigators examined results from 72 patients, 29 of whom underwent the inlay butterfly cartilage procedure and 43 of whom were treated with conventional underlay surgery. The tympanic-membrane closure rate and audiologic results were similar for the two techniques, but the average duration of surgery for inlay tympanoplasty was about half of that for the other operation (29.9 minutes vs 58.9 minutes, respectively).[30]

Similar results were reported in a study by Kim et al, in which 56 patients underwent inlay butterfly cartilage tympanoplasty, and another 56 individuals were treated with conventional underlay tympanoplasty. Surgical and functional success were comparable between the two procedures, but the duration of the inlay surgery was again about half of that for the underlay technique. Moreover, the visual analogue ̶ scale score for perioperative pain was lower for the inlay operation than it was for the underlay surgery (1.5 vs 4.9, respectively).[31]

A literature review by Jumaily et al found that tympanic membrane perforation closure rates for inlay butterfly transcanal cartilage tympanoplasty ranged from 71-100%. In a separate cohort, of pediatric and adult patients, the investigators reported complete closure in 21 of 32 perforations (66%) repaired with the procedure, with the mean air-bone gap dropping from 13.4 dB to 6.9 dB.[32]

A study by Ryan and Briggs found the overall success rate of overlay graft tympanoplasty to be 96.6%. For type 1 procedures, the success rate was 98.75%, while, when combined with intact canal wall mastoidectomy or modified radical mastoidectomy, the success rates for overlay tympanoplasty were 93.8% and 95%, respectively.[33]

A prospective study by Ranguis et al of endoscopic tympanic membrane perforation (TMP) repair in children without cholesteatoma found that lateral graft tympanoplasty had similar perforation closure rates and hearing outcomes as interlay tympanoplasty. The closure rate in both procedures was 88%, while serviceably normal postoperative hearing was found in 82% of the ears that had undergone the lateral graft surgery and in 78% of those that had undergone the interlay procedure.[34]

Preoperative preparation of the ear for surgery consists of eliminating infection whenever possible. Preoperative preparation of the patient includes convincing the smoker to cease tobacco use during the immediate postoperative period. Smoking has been found to have significant prognostic implications with regard to the success of tympanoplasty.[35]

Postoperative care is identical for office treatment and operating room repair techniques. Instruct patients to keep water out of their ears. When incisions and ear canal packing are present, use protective dressings, which are commercially available. Otherwise, silicone rubber plugs (also commercially available) or cotton balls waterproofed with a little petroleum jelly suffice.

Risk of cholesteatoma formation, either through the natural course of the disease or from squamous epithelium trapped during treatment, requires regular follow-up care for all patients postoperatively. Several annual visits should be the minimum once tympanic membrane perforation (TMP) healing is verified. Untreated TMP may not require regular follow-up care if a patient can be relied upon to seek medical advice if hearing changes or persistent drainage from the ear is noted. Location of the TMP informs the timing and frequency of follow-up care. Perforations in the pars tensa (stiff portion of the drum) are less likely to lead to complications.

The exceptions are pars tensa perforations located at the annulus or rim of the tympanic membrane. Tympanic membrane perforations (TMPs) in this location are at risk of developing middle ear cholesteatoma from migration of surface epithelium into the middle ear. Perforations in the pars flaccida (the portion without a fibrous center layer) are more frequently associated with complications and require more frequent follow-up care.

Each operation carries a risk of exacerbating hearing loss. Exact incidence of such hearing loss is unclear, with reported rates varying widely in the medical literature. In one series, approximately 1 per 500 operations resulted in much worse hearing. In another, the rate was nearly 2% for some degree of loss. Of 1000 patients, expect one to experience a perforation and four to endure lost hearing. In a small group of patients, persistent eustachian tube dysfunction leads to late complications, such as cholesteatoma, reperforation, or middle ear effusion. When the underlay technique of tympanoplasty is used, incidence of intratympanic cholesteatoma is less than 1%.[24]

Overlay tympanoplasty is more technically challenging, requiring stripping of the epithelial layer of the tympanic membrane, and is associated with the risk of lateralization of the tympanic membrane and blunting of the anterior angle (with the possible ensual of conductive hearing loss). However, this technique does have very high success rates for closure of perforations with both endoscopic and microscopic visualization techniques.[36]

Uncomplicated tympanic membrane perforation (TMP) requires no treatment. Perforations remain stable, and prognosis for absence of morbidity is good. Repaired drums reperforate in as many as 10% of patients. Potential for late perforation and the potential for formation of cholesteatoma mandate regular follow-up care for many years after apparently successful surgery.