Cholesteatoma

A cholesteatoma consists of squamous epithelium that is trapped within the middle ear space; it can erode and destroy vital structures within the temporal bone.

Throughout the early half of the 20th century, cholesteatomas were classically managed by exteriorization. The mastoid air cells were exenterated, the posterior wall of the external auditory canal was removed, and the opening into the resultant cavity was enlarged to ensure adequate air exchange, allow visual inspection, and make surveillance possible.

During the 1950s and 1960s, the House Otologic Group developed a new approach in which the basic underlying anatomic structure of the ear and temporal bone was left intact, principally by preserving the ear canal wall. This created great controversy, resulting in surgeons aligning themselves with either the old "canal wall–down" (ie, open cavity) procedure[6] or with the new "canal wall–up" (ie, closed cavity) method.[7]

In the United States, the majority of otologic and neurotologic surgeons have now migrated to an intermediate position, using both techniques and selecting the open or closed cavity procedure on a case by case basis.

Cholesteatomas cause bony erosion by either of the following mechanisms[8] :

1. Consistent pressure applied over time, resulting in bony remodeling
2. Osteoclastic activity enhanced by enzymatic processes occurring at the margin of an infected cholesteatoma

Using a scanning electron microscope, a study by Wiatr et al found that cholesteatomas with an irregular matrix structure tend to cause more destruction to the middle ear bone walls than do those with a regular, layered structure.[9]

A study by Rosito et al suggested that in patients with posterior epitympanic cholesteatoma confined to the pars flaccida or a two-route cholesteatoma involving both the pars flaccida and pars tensa, the chance of having a labyrinthine fistula in the lateral semicircular canal is increased. In study patients with these cholesteatoma growth patterns, the prevalence of labyrinthine fistula in the lateral semicircular canal was 5.0%, while in patients with other growth patterns, the prevalence altogether was 0.6%.[10]

Occasionally, extratemporal complications can arise in the neck, CNS, or both. Brain dysfunction can occur when a cholesteatoma within the cranium grows large enough to produce mass effect.

Generally, three types of cholesteatoma are identified: congenital, primary acquired, and secondary acquired.

Congenital cholesteatoma

Congenital cholesteatomas arise as a consequence of squamous epithelium trapped within the temporal bone during embryogenesis. They are keratin-filled cysts that are found in the anterior-superior quadrant and are identified most commonly in early childhood.[11]

Congenital cholesteatomas result in conductive hearing loss by obstructing the eustachian tube and consequently accumulating middle ear fluid. They can also expand posteriorly to encase the ossicular chain, another cause of conductive hearing loss.

Contrary to other cholesteatomas, the congenital subtype can be identified behind an intact, normal-appearing tympanic membrane. Prior history in the child of recurrent suppurative ear disease, previous otologic surgery, or tympanic membrane perforation is uncommon.[1, 2, 3, 4]

Bilateral congenital cholesteatoma is extremely rare, with a study by Lee et al finding that out of 604 children with congenital cholesteatoma, 1.8% had the bilateral form.[12]

Primary acquired cholesteatoma

A primary acquired cholesteatoma results from tympanic membrane retraction. A classic case develops from progressive deep medial retraction of the pars flaccida into the epitympanum (attic), slowly eroding the lateral wall of the epitympanum (scutum). This results in a slow expansion of the epitympanum lateral wall.[13]

The tympanic membrane continues to retract medially until it passes over the heads of the ossicles and into the posterior epitympanum, often causing ossicular destruction. Deafness and vertigo may result due to the erosion of the tegmen mastoideum as the cholesteatoma encroaches posteriorly into the aditus ad antrum and the mastoid, exposing the dura and/or eroding the lateral semicircular canal.[14]

Retraction of the posterior quadrant of the tympanic membrane into the posterior middle ear results in the second type of primary acquired cholesteatoma. The drum initially adheres to the long process of the incus; as a result of continued retraction medially and posteriorly, the superstructure of the stapes is enveloped by squamous epithelium, which retracts into the sinus tympani.

Upon surgical removal, it is commonly discovered that cholesteatomas arising from the tympanic membrane have caused facial nerve dehiscence, as well as destruction of the stapedial superstructure, resulting in a challenging removal from the sinus tympani.

Secondary acquired cholesteatoma

Secondary acquired cholesteatomas result directly from injury to the tympanic membrane, frequently in the form of perforations caused by acute otitis media, trauma, or surgical manipulation. Posterior marginal perforations, as opposed to central perforations, are a common source of these cholesteatomas. Deep retraction pockets trap desquamated epithelium, which leads to cholesteatoma formation as well.

Cholesteatomas are a relatively common reason for otologic surgery (biweekly in tertiary otologic practices). Death from intracranial complications of cholesteatoma is now uncommon, with this change being attributable to earlier recognition, timely surgical intervention, and supportive antibiotic therapy. Cholesteatomas remain a relatively frequent cause of permanent, moderate conductive hearing loss in children and adults.

The exact worldwide incidence of cholesteatomas is unknown, although the incidence has reportedly declined in recent decades; this can be attributed to earlier recognition, timely surgical intervention, and the widespread use of ventilation tubes. The majority of cholesteatoma cases are acquired, with boys making up the preponderance of these.

Surgical excision is generally successful. Cholesteatomas continue to grow if not removed, and multiple surgical procedures may be necessary in cases of recurrence or failure to completely excise the cholesteatoma during the initial surgery. Complications may arise in rare events, including the following:

• Brain abscess
• Unilateral hearing loss
• Vertigo
• Facial nerve dehiscence leading to paralysis
• Meningitis
• Persistent otorrhea

Canal wall–down (open cavity) tympanomastoidectomy offers a very low rate of recurrence or persistence of cholesteatomas. Repeat procedures occur in less than 5% of patients. This compares quite favorably with the 20-40% recurrence rates associated with closed-cavity techniques (canal wall–up).[6]

Nonetheless, as the ossicular chain and/or tympanic membrane cannot always be completely restored to normal, cholesteatoma remains a relatively common cause of permanent, moderate conductive hearing loss.

A literature review by van der Toom et al reported that canal wall–up and canal wall–down tympanoplasty with mastoid obliteration had recurrent and residual cholesteatoma rates that were similar to or better than those for nonobliterative surgery. In canal wall–up tympanoplasty with mastoid obliteration, the recurrent and residual cholesteatoma rates were 0.28% and 4.2%, respectively, while for the canal wall–down procedure with mastoid obliteration, the rates were 5.9% and 5.8%, respectively.[15]

A study by Rosito et al linked cholesteatoma with sensorineural hearing loss. In an analysis of 115 patients with middle ear cholesteatoma on one side, greater bone-conduction thresholds were found in the affected ear than in the contralateral ear at various frequencies. It was also found that the larger the air-bone gap in the affected ear, the greater the damage to the inner ear.[16]

Mortality

Death from intracranial complications of cholesteatoma is uncommon due to early recognition, timely surgical intervention, and supportive antibiotic therapy.

Painless otorrhea

The hallmark symptom of cholesteatoma is a painless otorrhea, either unremitting or frequently recurrent. When the cholesteatoma becomes infected, it may be extremely difficult to eradicate. Owing to a lack of blood supply to the cholesteatoma, systemic antibiotics cannot be delivered to its center. Topical antibiotics can often surround the cholesteatoma, suppress infection, and penetrate a few millimeters toward the center of the mass; however, large infected cholesteatomas are resistant to any type of antimicrobial therapy. Consequently, otorrhea either persists or recurs despite frequent and aggressive treatment with antibiotics.

Hearing loss

Hearing loss is also a common symptom of cholesteatomas. Large cholesteatomas interfere with sound transmission by filling the middle ear space with desquamated epithelium, with or without associated mucopurulent discharge. Ossicular damage frequently occurs and can also produce or may magnify a conductive loss. (See the image below.)

A study by Yehudai et al of 124 pediatric patients with chronic otitis media, without or without cholesteatoma, found a significant association between the presence of cholesteatoma in this disease and the degree of sensorineural hearing loss at 2000 Hz.[17]

Vertigo

Vertigo, a progressive symptom of cholesteatoma, occurs infrequently due to early diagnosis of the disease. It can result when the middle ear ossicles are eroded and produce a labyrinthine fistula or when the cholesteatoma is lying directly on the stapes footplate. Vertigo is a worrisome symptom, as it may presage the development of more serious complications.

Facial nerve palsy

Rarely, cholesteatoma presents with facial nerve paralysis. Please see the Complications subsection below for further details. 

Central nervous system

Occasionally, cholesteatoma initially presents with symptoms of CNS complications, sigmoid sinus thrombosis,[18] epidural abscess, or meningitis.

Craniofacial abnormalities

A Danish study indicated that in persons with a cleft palate, the risk of cholesteatoma is 20-fold that of the general population; siblings of these individuals were also determined to be at somewhat increased risk. Persons with a cleft lip, however, were found not to have a higher cholesteatoma risk. The historical cohort study included 8593 persons with a nonsyndromic orofacial cleft, as well as 6989 siblings.[19]

On physical examination, the most common signs of cholesteatoma formation are drainage and granulation tissue in the ear canal and middle ear space. Quite frequently, the only finding on physical examination is an ear canal filled with mucoid drainage and granulation tissue; sometimes, eliminating the infection and resolving the granulation tissue with either systemic antibiotics or ototopical antibiotic drops is impossible. When ototopical therapy is successful, a deep tympanic retraction pocket may be seen in the pars flaccida (the portion of the tympanic membrane that is superior to the short process of the malleus) or in the posterior quadrant of the tympanic membrane.

In more than 90% of cases, a tympanic membrane perforation is also present. Congenital cholesteatomas are an exception to this, with the eardrum often remaining intact until the middle ear component is quite large.

Occasionally, cholesteatoma is produced by surgical implantation of squamous epithelium that manifests prior to disruption of the tympanic membrane, but even in such cases, the cholesteatoma eventually produces a tympanic membrane perforation.[20]

Very seldom is cholesteatoma first identified based on one of its complications; however, this occasionally happens in children. An infection associated with the cholesteatoma can erupt through the inferior mastoid cortex and manifest as a neck abscess. Rarely, cholesteatoma can manifest with signs and symptoms of CNS complications, sigmoid sinus thrombosis, epidural abscess, or meningitis.

Mastoiditis

Mastoiditis develops due to infection of the mastoid cells. Symptomatic coalescent mastoiditis (which is a separate entity from simple mastoid effusion) is a rare complication of both acute otitis media and chronic otitis media, with or without cholesteatoma. Nonetheless, mastoiditis can be serious due to its proximity to the posterior cranial fossa, lateral sinuses, facial nerve canal, semicircular canals, and the petrous tip of the temporal bone. A study that reviewed almost 3000 cases of chronic suppurative otitis media (CSOM) in a 9-year period in Turkey reported 25 cases of mastoid abscess.[21] Clinical mastoiditis may present with fever, posterior ear pain and/or local erythema over the mastoid bone, edema of the pinna, or a posteriorly and downward displaced auricle. In coalescent mastoiditis, CT scanning demonstrates characteristic loss of trabecular bone[22] .

Antibiotics for the treatment of mastoiditis should include coverage for Staphylococcus aureus, Pseudomonas, and enteric gram-negative rods, as well as Streptococcus pneumoniae and Haemophilus influenzae. If patients do not respond to conservative therapy with intravenous (IV) antibiotics, further intervention is warranted. When cholesteatoma is present, tympanomastoidectomy should be considered to remove necrotic bone in the mastoid and cholesteatoma deposits.

Facial nerve palsy

The facial nerve is vulnerable to infection during chronic otitis media, and facial palsy may occur as a complication of cholesteatoma, as well as tympanomastoid surgery. It typically arises in association with more advanced lesions of chronic ear infections. CSOM, which is characterized by persistent otorrhea through the tympanic perforation and can occur with or without cholesteatoma, can be complicated by facial nerve palsy, owing to involvement of the dehiscent facial nerve or direct bony erosion of the facial canal.[22, 23] The onset is usually gradual. In one case series of 70 patients with complicated CSOM, 14% of the patients had accompanying facial palsy.[24] Treatment of facial paralysis in the setting of CSOM, with or without cholesteatoma, requires surgical intervention.[22]

Intracranial complications

Intracranial complications—such as suppurative thrombophlebitis of the lateral and/or cavernous sinuses, meningitis, and intracranial abscesses—are potentially life-threatening and require immediate intervention.[21]  These complications are rare, however.

No laboratory tests or biopsies are generally necessary for the diagnosis of cholesteatoma, as the diagnosis relies heavily on clinical history, physical examination, and radiographic findings. CT scanning is the diagnostic imaging modality of choice for these lesions, as it can detect subtle bony defects in the setting of a middle ear and/or mastoid lesion. Histologically, surgically removed cholesteatoma specimens demonstrate typical squamous epithelium. The histology is indistinguishable from that of sebaceous cysts or keratomas removed from any other part of the body.

Audiometry should be performed prior to surgery whenever possible. Air and bone conduction, speech reception threshold, and speech discrimination tests should all be conducted before the proposed operative procedure, to establish a hearing baseline. It is acceptable to forgo audiometric testing if, as occurs infrequently, cholesteatoma gives rise to a serious complication that requires urgent surgery.

CT scanning is the imaging modality of choice in the diagnosis of cholesteatoma, as it can detect subtle bony defects in the temporal bone. However, CT scans cannot always distinctly distinguish between granulation tissue and cholesteatoma. Even high-resolution CT scanning cannot reliably determine the full extent of the disease.

As the otologic surgeon cannot always predict what is needed in the operating room based on findings from the preoperative evaluation, the otolaryngologist must be prepared for intraoperative temporal bone aberrations.[25, 26, 5]

Subtle bony defects that can be detected on CT scanning include the following[5] :

• Scutal erosion[27]

• Labyrinthine fistula

• Tegmen defect

• Ossicular erosion or discontinuity

• Anomalies, erosion, or invasion of the fallopian canal (facial canal)

In a study of 64 patients with middle ear cholesteatomas, Gaurano and Joharjy found that the diagnosis of cholesteatoma was suggested by specific characteristics found on CT scans. These included expansion of the aditus and mastoid antrum (92%) and ossicular erosion (92%). Preoperative CT scanning in the study had a 97% correlation with surgical and histopathologic findings.[26]

Some surgeons believe that any patient with a cholesteatoma who is scheduled for surgical intervention should have a preoperative CT scan; it provides useful information in every circumstance, and, consequently, the expense of the scan and the radiation exposure involved are typically justified.

Other surgeons reserve preoperative imaging only for special cases and are quite comfortable performing surgery without it. These surgeons may nonetheless request a preoperative CT scan in the following circumstances:

• Unclear diagnosis

• Patient is adamant about avoiding an operation

• CT scanning will help the patient and/or family to assess the risks of ossicular involvement

• The underlying anatomy is indeterminate and the extent of disease is unclear as a result of previous surgery

• Concern for congenital disorders (eg, atresia cases, craniofacial anomalies)

• Labyrinthine fistula or erosion of the fallopian canal is suspected

A study by Baba et al indicated that temporal subtraction CT (TSCT) scanning in combination with conventional CT imaging is superior to conventional CT scanning alone in diagnosing recurrent/residual cholesteatoma following primary cholesteatoma surgery. TSCT plus conventional CT scanning better detected new, progressive erosive bone changes and had higher sensitivity for finding recurrent/residual cholesteatoma. For example, the mean sensitivity for experienced radiologists using TSCT plus CT scanning was 0.77, compared with 0.52 for those using only conventional CT scanning.[28]

Avoidance of surgery

Patients who are poor surgical candidates or who wish to avoid surgery for other reasons can be better advised about the risks of nonsurgical management if a CT scan has been performed and evaluated. The presence of extensive disease, a labyrinthine fistula, encroachment on the fallopian canal, and involvement of the oval window niche increase the risk associated with conservative management.

Risk assessment

If ossicular involvement is apparent on preoperative CT scanning, patients should be counseled that ossicular removal may be necessary and that significant postoperative conductive hearing loss should be expected.

MRI reveals cholesteatoma as isointense on T1 sequences without enhancement from contrast and hyperintense on T2 sequences. MRI is used when very specific clinical concerns, such as the following, exist[5] :

• Dural involvement or invasion

• Subdural or epidural abscess

• Brain herniation into mastoid cavity

• Inflammation of membranous labyrinth or facial nerve

• Sigmoid sinus thrombosis

• Meningitis

A number of articles suggest that diffusion-weighted MRI may be able to distinguish between recurrent or persistent middle ear cholesteatoma, scar tissue, and granulation tissue. If future studies verify a high sensitivity and specificity for this modality, it may become possible to replace routine second-look procedures with high-quality diffusion-weighted MRI.[29, 30]

A literature review by Muzaffar et al indicated that following ear surgery, diffusion-weighted MRI is sensitive and specific for determining the existence of recurrent or residual cholesteatomas, with non-echoplanar imaging (non-EPI) techniques having greater sensitivity and specificity than echoplanar imaging (EPI) sequences. The investigators found that EPI studies had a sensitivity and specificity of 71.82% and 89.36%, respectively, while non-EPI studies had a sensitivity and specificity of 89.79% and 94.57%, respectively.[31]

A study by Lips et al compared the diagnostic performance of 1.5 T to that of 3 T non-EPI DWI, as employed to detect residual and/or recurrent cholesteatoma. The investigators showed 1.5 T to be preferred over 3 T for the detection of residual/recurrent cholesteatoma, with the sensitivity being 96% versus 80%, respectively, and the specificity, 59% versus 46%, respectively.[32]

A study by Yamashita et al indicated that fusing images from high-resolution three-dimensional diffusion-weighted MRI and multi-detector row CT scanning is useful in operative planning for cholesteatoma surgery. In this study, involving 12 patients, the investigators found a good correspondence between the location and extent of cholesteatoma, as seen on the fused images as well as intraoperatively.[33]

A study by Locketz et al indicated that combining temporal bone CT scanning with PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) diffusion-weighted MRI is superior to PROPELLER diffusion-weighted MRI alone for the preoperative identification and localization of cholesteatomas. The diagnostic sensitivity, positive predictive value, and negative predictive value of the CT/MRI-scan combination were 88%, 88%, and 75%, respectively, compared with 75%, 86%, and 60%, respectively, for PROPELLER diffusion-weighted MRI alone.[34]

Generally, all cholesteatomas should be excised. The only absolute contraindications are patient comorbidities that prevent surgical intervention. For example, the absence of hearing in the contralateral ear is a relative contraindication to surgery. However, since cholesteatoma frequently presents a greater risk to residual hearing than surgery, removal usually remains the management option of choice in these clinical situations.

Depending on the selected procedure, approximately 5-40% of cholesteatoma operations are unsuccessful, with cholesteatoma persistence or recurrence manifesting at some point in the postoperative period. Persistence may appear as early as 5-6 months postoperatively, although in some cases it may be delayed for many years. Consequently, close follow-up care with an otolaryngologist is important.

The applicability of using small otoendoscopes as part of the surgical management of cholesteatomas is being explored.[35] A study by Hunter et al of pediatric patients with cholesteatoma, comparing total endoscopic ear surgery with microscopic surgery and combined endoscopic-microscopic procedures, found that results were similar between the endoscopic and microscopic techniques with regard to hearing outcomes, complication rates, recurrence, and residual disease rates.[36]

Surgical therapy consists of complete removal of the cholesteatoma. In certain circumstances, the surgeon can make the decision to use a canal wall–up (closed) or canal wall–down (open) technique. (The intact bridge canal wall–down tympanomastoidectomy is a contemporary version of a modified radical tympanomastoidectomy with preservation of the bridge, which is the most medial portion of the posterosuperior meatal wall.)

Canal wall–down operations have the highest probability of success with regard to treating cholesteatoma. In the canal wall–up procedure, however, the canal wall is preserved, and the normal appearance is maintained; nonetheless, there is a risk of persistent and/or recurrent cholesteatomas. Consequently, most surgeons advise an obligatory second-look tympanomastoidectomy 6 months to 1 year after the initial canal wall–up operation.[37, 38]

At the time of the second look, small amounts of residual disease can frequently be removed prior to the development of either complications or massive recurrence. Increasing evidence suggests that diffusion-weighted MRI may be able to accurately detect cholesteatoma recurrence and, in some cases, replace a second-look procedure.[39]

If the patient has had several episodes of recurrent cholesteatoma and wishes to avoid future operations, the canal wall–down technique is most applicable. In addition, it is safer for patients who are unwilling or unable to return for a second-look procedure.[6, 7, 40]

Some congenital anomalies are known to be associated with a lifelong history of eustachian tube dysfunction, and in some individuals, previous surgical procedures have irreversibly injured the eustachian tube. These again are patients in whom an open-cavity operation often is best.

Osborn et al reported the results from 420 children who underwent 700 operations and concluded that most children with cholesteatoma can be managed with an intact–canal wall technique.[41]

Sometimes, the decision as to which procedure to perform is confirmed during surgery, when a clear understanding of the extent of the disease has been obtained.

No operation can be successful unless the goals of the procedure are kept clearly in mind. These include the following:

• To make the ear safe by eliminating cholesteatoma and chronic infection

• To make the ear problem-free for all usual activities of daily living, including swimming

• To conserve residual hearing

• To improve hearing when possible

• To provide an acceptable cosmetic appearance

Preoperatively

A careful discussion of the advantages and disadvantages of canal wall–up and canal wall–down procedures is useful. If canal wall–down surgery is considered preoperatively, showing the patient a picture of a well-crafted meatoplasty, as shown below, can help the individual to form a clear understanding of the expected postoperative appearance.

Advantages and disadvantages of the canal wall–up procedure include the following:

• Normal auricular appearance

• Hearing aids easy to fit

• No routine otologic cleaning

• High tolerance for water exposure

• Usually a staged procedure

• Relatively high rate of recurrent or persistent cholesteatomas

Advantages and disadvantages of the canal wall–down procedure include the following:

• Enlarged meatus

• Hearing aids difficult to fit

• Annual or semiannual canal cleaning

• Occasional problem with water exposure (vertigo may develop after exposure to water or cold air)

• Usually a single procedure

• Low rate of persistent or recurrent cholesteatoma

Intraoperatively

Often, the best plan is to reserve the decision about how to manage the canal wall until the operation has begun and a better understanding of the extent of the disease has emerged. Some intraoperative findings that favor a canal wall–down, or open, technique, include the following[6] :

• Involvement of sinus tympani

• Involvement of medial end of canal wall, with the cholesteatoma wedged laterally between the heads of the ossicles in the epitympanum and medial canal wall

• Otitis or irremovable cholesteatoma in the area around the opening to the eustachian tube or in the most inferior portions of the middle ear space (often calls for a true radical mastoidectomy)

• Large defects in the canal wall; frequently, the best plan is to convert the operation to an open-cavity procedure (in contrast, small defects in the canal wall are readily repaired)

• Labyrinthine fistula; if the cholesteatoma matrix is left over the fistula so as not to expose it, then the canal wall must be removed; otherwise, the epithelium is trapped within the mastoid cavity, resulting in cholesteatoma recurrence; if the cholesteatoma matrix is removed from the fistula, some surgeons are comfortable leaving the canal wall up

Most surgical procedures for cholesteatomas in the United States are now performed through an incision behind the ear combined with an incision in the external auditory canal, but the procedure can be performed through an extended incision starting in the ear canal (endaural).

Regardless of which technique is used, all of the mastoid air cells should be removed. If the ossicles are involved, they must be removed to avoid recurrence.[39] Reconstruction of the ossicular chain can occur either at the end of the primary procedure or as part of a secondary operation.

The tympanic membrane is usually reconstructed. If a canal wall–up technique is used, missing bone is replaced with a cartilage graft. If a canal wall–down procedure is selected, a large meatoplasty is created to allow adequate air circulation into the mastoid cavity that arises as a consequence of removing the posterior canal wall.

Essential features of a canal wall–up procedure include the following[7] :

• Removal of all infected air cells

• Functioning eustachian tube

• Well-maintained middle ear space

• Adequate communication between the mastoid and the middle ear space through the aditus ad antrum or generous facial recess

• Elimination of any bony epitympanic defect with cartilage graft

Essential features of a canal wall–down procedure include the following:

• Removal of all air cells, including those within the retrofacial, retrolabyrinthine, and subarcuate air cell tracts

• Removal of the lateral and posterior walls of the epitympanum such that the tegmen mastoideum and tegmen tympani become a smooth, featureless plane

• Amputation of the mastoid tip (usually advisable)

• Saucerization of the lateral margins of the cavity

• Lowering of the posterior bony external auditory wall to the level of the facial nerve

• Exteriorization of the anterior epitympanic recess by removing the cog

• Enlargement of the meatus (to at least twice its normal size) by removing conchal cartilage

• Lowering of the medial end of the external auditory canal toward the floor of the hypotympanum

Some surgeons prefer a subcortical technique that starts with the removal of bone medially through the ear canal. The epitympanum is progressively enlarged, and the posterior canal wall is removed from the inside out. Bone removal is limited to that necessary to excise the cholesteatoma.

Such a subcortical, or inside-out, mastoidectomy combines some of the advantages of canal wall–up and canal wall–down techniques but commits the surgeon to a canal wall–down operation if the cholesteatoma has extensive mastoid involvement.[42, 43]

Canal wall-reconstruction tympanomastoidectomy

In a retrospective case review of 273 patients (mean age 35 years) with chronic otitis media with cholesteatoma, Walker et al found that an alternative surgical procedure, canal wall–reconstruction (CWR) tympanomastoidectomy with mastoid obliteration, produced good long-term results. The investigators, who examined the surgical outcomes on 285 ears (average follow-up 4.29 years), determined the rate of failed procedures—those requiring conversion to open cavity or subtotal petrosectomy—to be only 2.6%.[44]

The investigators concluded that use of CWR tympanomastoidectomy avoids the long-term drawbacks of canal wall–down mastoidectomy while offering surgeons excellent exposure of the middle ear and mastoid.

Management of the complications of cholesteatoma

Labyrinthine fistula

Sometimes, the existence of a labyrinthine fistula is suggested on preoperative CT scans; at other times, the presence of a fistula is a complete surprise. Initially, the desquamated epithelium should be removed, carefully leaving the matrix over the horizontal canal. Blunt probes are used to locate the fistula by palpation. If the fistula appears to be superficial, the matrix is gently removed at the end of the case and the defect is covered with fascia. However, if the fistula is large and it appears that the cholesteatoma matrix is attached firmly to the membranous labyrinth itself, leaving the matrix in position should be considered. Debate continues as to whether hearing loss is more likely if the matrix is removed.

If the membranous labyrinth is opened at any point during the procedure, broad-spectrum antibiotics and steroids should both be administered immediately. Bacterial labyrinthitis and inflammation pose the biggest risk to hearing.[45] Fistulas involving the oval window area should be treated according to the same principles. Violation of the vestibule itself is much more likely to produce hearing loss than violation of one of the semicircular canals.

Occasionally, a canal fistula is created during the surgical procedure. If such a fistula involves one of the semicircular canals, then it should be sealed with soft tissue (preferably fascia) and antibiotics and steroids administered. These patients are quite likely to have significant balance disturbance in the immediate postoperative period, but a significant number recover with little or no hearing loss if appropriate antibiotic therapy and steroids are provided in the postoperative period.

Brain herniation

Brain herniation through the tegmen of the middle fossa has a characteristic glistening, shiny appearance. The presence of clear fluid associated with such a lesion should raise suspicion of a brain hernia and cerebrospinal fluid leak. MRI and CT scanning can often help to clarify the diagnosis preoperatively.

Options for managing a brain hernia fall into two basic categories: reconstruction of the mastoid cavity and obliteration of the mastoid cavity. If reconstruction is chosen, glialized brain can be removed simply by sharply excising it; any viable brain can be pushed back up into the middle cranial fossa. If the defect is large, intradural and extradural repair of the dural defect should be considered.

The alternative involves obliterating the middle ear, external auditory canal, and mastoid by removing the posterior canal wall, obliterating the eustachian tube, filling the defect with abdominal fat, and oversewing the external canal. This is an especially appealing option if hearing is very poor in the afflicted ear. If all of the squamous epithelium has been removed, obliteration ensures a safe, well-healed, problem-free ear, although maximal conductive hearing loss is unavoidable.

Postoperative details

Regular office visits are necessary following surgery. Most surgeons prefer to see the patient after 7-10 days and allow the individual to remove the dressing at home after 24-48 hours. If nonabsorbable sutures or staples are used, they must be removed at 7-10 days. If suture or staple removal is unnecessary, some surgeons delay the first postoperative visit for as long as 2-3 weeks. Open cavities heal slowly, and 12-24 weeks are often required for full epithelialization.

Postoperative management

Postoperative treatment regimens for canal wall–down procedures vary considerably. The wick or packing in the external auditory canal (EAC) is removed at the first postoperative visit, 7-10 days after surgery. Antibiotic otic drops are prescribed twice daily for 10 days. Open cavities require variable amounts of cleaning over the first 4-8 postoperative weeks. The first cavity cleaning occurs at the postoperative visit 2-3 weeks after the procedure, and such cleaning can be accomplished regularly in an office setting every 2-3 weeks, depending on how quickly the cavity epithelializes. Often, the patient is asked to fill the cavity with peroxide daily, starting 1-2 weeks postoperatively, or to irrigate the cavity with an alcohol-vinegar solution. This limits the amount of superficial infection.

Control of granulation tissue

Frequently, granulation tissue forms in the open cavity as it heals. Granulation tissue may be helpful because it can contract the size of the cavity, resulting in a much smaller postoperative cavity than would be the case if the initial defect epithelialized. On the other hand, granulation tissue can obliterate medial portions of the cavity, including the newly grafted drum, and compromise hearing outcome. Exuberant granulation tissues can significantly delay epithelialization. Steroid creams, steroid-containing drops, and regular applications of gentian violet can be used to help control the development and extent of granulation tissue. Silver nitrate cautery also effectively eliminates or reduces granulation tissue. However, silver nitrate produces a chemical burn, the depth of which is difficult to control, so extra caution must be used around delicate or sensitive structures such as the horizontal semicircular and facial nerve in order to avoid iatrogenic injury.

Infection control

Often, a superficial infection develops that can be effectively controlled using topical antibiotic drops. The causative organisms are predominantly gram-negative, with Pseudomonas species being the single most common pathogens; gram-positive organisms, including Streptococcus and Staphylococcus species, account for 20-30% of recovered organisms. Aminoglycoside and fluoroquinolone topical preparations provide appropriate antibacterial spectra for these organisms. The complete absence of potential ototoxicity among the fluoroquinolones makes them appealing. If a nonsteroidal otic preparation is desired, either ciprofloxacin or ofloxacin solution is an excellent choice. If granulation tissue is present, steroid-containing drops may be preferred. In such cases, ciprofloxacin/dexamethasone (Ciprodex) is an excellent choice. Antibacterial creams containing fluoroquinolones can also be used. Occasionally, if granulation tissue appears to be overwhelming, steroid creams alone are useful. Finally, if a superficial fungal infection or candidiasis develops, nystatin-triamcinolone (Mycolog) or clotrimazole (Mycelex) cream is usually sufficient to eradicate the infection.

Endoscopic ear surgery or endoscopic-assisted ear surgery has many advantages in comparison with traditional microscopic techniques, as the endoscope allows for a broader and potentially closer view of the surgical field than does the microscope. A transcanal endoscopic-assisted approach has been found to be particularly helpful in the setting of attic cholesteatoma. Endoscopic ear surgery has been proposed to improve outcomes based on the following principles[46, 47, 48, 49, 50, 51] :

• Improved visualization
• Allowance of the surgeon to complete more tasks via transcanal approaches, reducing the need for a postauricular incision and therefore avoiding the associated morbidity
• Reduction in cholesteatoma recidivism rates 

The use of endoscopes in chronic ear surgery can reduce cholesteatoma recidivism rates. Ayache et al published a large retrospective review of 350 patients who had surgery for cholesteatoma. After completing the surgery using a microscope, the investigators introduced the endoscope and found residual cholesteatoma in 44% of cases overall, and in 76% of cases where cholesteatoma involved the retro-tympanum.[46]  A large retrospective review by Sajjadi of 249 primary cholesteatoma cases with a minimum follow-up of 2 years reported that the use of endoscopy at the time of primary cholesteatoma surgery revealed “cholesteatoma remnants” in 22% of closed-cavity cases.[47]

With endoscopic surgery, several authors have noted a significant decrease in residual cholesteatoma at the time of second-look surgery; however, others have not. When endoscopes are used during primary cholesteatoma surgery as an adjunct (canal wall up), residual cholesteatoma rates found on follow-up range anywhere from 0% to 17%.[47, 51] Only one of these studies had a control arm; nonetheless, the recurrence rates are almost as low as expected for canal wall–down mastoidectomies[46, 47, 49, 51] . 

Stenosis

Postoperative stenosis is usually a consequence of exuberant granulation tissue and is more likely to occur when a postoperative infection is present. Principles of prevention include infection control and suppression of granulation tissue.

Surprisingly, the gentle pressure of expanded packing often slowly increases the size of the canal. By keeping the packing in place for several months, a 1- to 2-mm nonfunctional medial canal can be expanded to 4-5 mm, which is large enough to conduct sound efficiently and prevent additional conductive hearing loss.

If postoperative stenosis completely obliterates the cavity, revision of the cavity in an attempt to restore patency and improve hearing may be necessary. Split-thickness skin grafts limit the recurrence of postoperative stenosis.

Facial Nerve Injury

The most dreaded complication of tympanomastoidectomy is injury to the facial nerve. The incidence of permanent facial nerve injury following cholesteatoma surgery is not entirely certain, but it is probably less than 1% in the hands of experienced otologists who perform the operation regularly. Controversy exists as to whether or not facial nerve monitoring is helpful in reducing the risk of postoperative facial nerve injury.

Evaluation

The first step in managing a possible or recognized facial nerve injury is to decompress the nerve around the area thought to be injured. Bone should be removed a few millimeters proximal and distal to the damaged segment so that the injury can be clearly visualized.

Evaluation of the severity of injury is extremely difficult if the injured segment is in the middle ear, where the space in which the surgeon can operate is very limited. The horizontal semicircular canal limits exposure posteriorly, and the superstructure of the stapes limits exposure anteriorly. Consequently, accurate assessment of the severity of injury is especially difficult in this area.

If injury to the facial nerve is not recognized during the operation and the patient awakens with facial paralysis, the surgeon should wait several hours to make sure that this is not a consequence of the local anesthetic. If facial paralysis persists 3-4 hours beyond recovery from anesthesia, the packing should be removed.

If the surgeon is not absolutely sure that the facial nerve is anatomically intact, the patient should be taken back to surgery immediately, the nerve decompressed around the area of injury, and the severity of the injury assessed. Based on the assessment, the surgeon must decide whether or not to excise the injured segment. A consultation should be obtained if possible, and the resulting assessment and opinion should be documented.

If the facial nerve was clearly visualized at the time of surgery and the operating surgeon is absolutely certain that the nerve is anatomically intact, treat the injury like any other posttraumatic nerve paralysis. Begin electroneuronography testing approximately 72 hours postoperatively and start empiric steroid therapy. If, within the first 2-3 weeks, the compound action potential on the affected side drops to less than 10% of the compound action potential on the normal side, the patient should be taken back to the operating room for exploration.

Repair

If more than 50% of the diameter of a facial nerve is deemed nonviable because it has been cut, crushed, or stretched, then the injured segment should be resected and the nerve should be anastomosed or grafted.

If a primary anastomosis can be achieved without tension, this is the best method of repair. A primary anastomosis with small segments of missing nerve is possible, but only if the nerve can be mobilized and rerouted over a substantial portion of its length. This is not usually possible when surgery is limited to the mastoid and tympanic segment. If a primary anastomosis without tension cannot be achieved, then an interposition graft should be placed.

Monitoring

The routine use of facial nerve monitoring remains controversial. A 1990 survey showed that most experienced otologists do not believe that facial nerve monitoring is obligatory. Indeed, a large percentage of surgeons use such monitoring only in selected cases. These include in patients requiring revision surgery, patients who have had perioperative facial nerve weakness in the past, and patients in whom imaging studies show facial nerve anomalies. However, some surgeons believe that predicting cases in which the facial nerve is at risk is impossible and, consequently, believe that monitoring should be performed in every case. These surgeons see facial nerve monitoring as a precaution, much like electrocardiographic monitoring, that can potentially be useful in any given case.

Complete Sensorineural Hearing Loss

A 1-2% chance of total neurosensory hearing loss is associated with cholesteatoma removal. A cholesteatoma that has produced a labyrinthine fistula or that lies directly over the footplate is more likely to permanently lead to such loss.[45]

Graft Failure

In approximately 10-15% of patients undergoing cholesteatoma removal, the surgical graft fails, and a tympanic membrane perforation occurs that, if untreated, will be permanent. Such perforations, however, frequently can be eliminated with a revision operation.

Balance Disturbance

Long-term balance disturbance can occur with labyrinthine or middle ear injury but is uncommon, arising in less than 1% of patients.

Chondritis and Perichondritis

Perichondritis or chondritis occurs in less than 1% of patients. Care should be taken at the time of surgery to minimize the amount of exposed cartilage, as exposure and devascularization render the cartilage more susceptible to infection.

Perichondritis develops slowly and has the following symptoms: (1) increasing pain, erythema, and edema of the skin over the involved conchal or auricular cartilage and (2) occasional fluctuance.

Fluoroquinolones offer excellent coverage for these infections, achieving blood levels equal to those achieved with oral or IV antibiotic administration. As the blood supply to cartilage is relatively sparse, however, perichondritis and chondritis are slow to respond to antibiotic therapy.

Antibiotic therapy must be continued for a minimum of 3-4 weeks; often, 6 weeks of oral antibiotic therapy is required. If fragments of devitalized cartilage become sequestered, they require operative removal.

If no clinical response to antibiotic therapy occurs within 2-3 weeks or if the infection worsens during that period, operative drainage should be considered. A semicircular incision that parallels the margin of the antihelix minimizes the cosmetic impact.

Otorrhea

Persistent drainage from a canal wall–down cavity can arise for a number of reasons. Most commonly, it results from either a sequestered air cell that continues to harbor infection or a small area of osteitis. In such cases, the cavity as a whole heals up quite well except for a small area that remains covered with granulation tissue. The only solution is to remove the involved area.

If the area of osteitis is large and postoperative otorrhea has persisted for months or years, skin grafting should be considered. Skin grafts are especially useful in cavities that have developed mucosal (as opposed to squamous) epithelial linings on at least one occasion.

Sometimes, persistent or recurrent drainage is due to a residual cholesteatoma, in which case the only viable solution is reoperation to remove residual disease.

Foreign Bodies

Foreign bodies retained within the mastoid cavity or wound must be removed, as they can become the nidus for inflammation or infection. The most common foreign bodies are small metal fragments that result from the burr hitting the tip of the suction during mastoidectomy. Retained pieces or fragments of packing and/or shreds of cotton can similarly serve as a nidus of infection but can usually be removed in the office.

Dysgeusia

Many patients have alteration of taste on the anterior two thirds of the ipsilateral tongue for weeks after an otologic procedure due to exposure and/or sacrifice of the chorda tympani. This condition, however, usually resolves within a few months after surgery.

An open cavity should be problem-free once fully healed, provided that the patient returns to the office every 6-12 months for microscopic cleaning. During these débridements, variable amounts of desquamated epithelium and/or cerumen can be found to fill the depths of the mastoid cavity. Occasional areas of crusting may be present, behind which superficial areas of infection may have developed. Usually, removing the crust and exposing these areas to circulating air is sufficient to resolve the infection.

Home care may consist of regular installations of hydrogen peroxide or a one-to-one mixture of alcohol and white vinegar. Such installations may be administered daily, every other day, or weekly. Of note, the alcohol-vinegar combination is desiccating.

As the skin of the epithelialized cavity is normal squamous epithelium, filling the cavity once or twice a month with an emollient is sometimes helpful; baby oil or mineral oil is effective, as it may help to soften cerumen and reduce itching.

Most patients swim comfortably with an open cavity, but some develop vertigo when cold water enters the ear and stimulates the exposed horizontal semicircular canal. In such circumstances, the use of an earplug can effectively the block circulation of water over the exposed canal and eliminate vertigo. Children should be watched carefully the first several times they swim to make sure that they do not develop disequilibrium and vertigo while in water.

Each patient must be monitored for several years, as recurrence can occur long after the initial surgical procedure. Follow-up care should include semiannual or annual evaluations, even in patients who are asymptomatic. The frequency with which a patient with a canal wall–down mastoidectomy cavity needs to be seen in order to keep the ear free of desquamated epithelium and cerumen becomes readily apparent. Some patients may require follow-up evaluations as often as every 3 months for cavity cleaning, while others may need to be seen only once a year.

Patients who have had canal wall–up operations generally need a second-look procedure 6-9 months after the original operation. Once the second-look procedure has been completed, regular follow-up care at intervals of 6 months to 1 year are necessary in order to identify persistent or recurrent cholesteatoma.

Medical therapy is not a viable treatment for cholesteatoma. Patients who refuse surgery or whose medical condition makes a general anesthetic too hazardous should have their affected ears evaluated and debrided regularly. Regular evaluation can help to control infection and may slow cholesteatoma growth, although it does not stop further expansion or eliminate existing risk. The mainstay of microbial therapy should be topical, but systemic therapy is occasionally a helpful adjunct when concern for active infection exists.

Consultation with an otolaryngologist is mandatory, along with the assistance of a pediatric otolaryngologist and/or otologist, as deemed clinically necessary. Advice from a neurosurgeon is required to help manage an intracranial complication or when concern arises for CNS pathology.

Drug therapy is not currently part of the standard of care for cholesteatoma, with little utility even when lesions become infected. Owing to a lack of blood supply to the cholesteatoma, systemic antibiotics cannot be delivered to its center. Topical antibiotics often surround the cholesteatoma, suppress infection, and penetrate a few millimeters toward its center; however, large infected cholesteatomas are resistant to any type of antimicrobial therapy. Consequently, otorrhea either persists or recurs, despite frequent and aggressive treatment with antibiotics. In the operative setting, it is our practice to place fluoroquinolone and steroid-impregnated topical solution into the middle ear and/or dissected mastoid cavity. Furthermore, after the cholesteatoma is extirpated surgically, it is also our practice to place patients on a 10-day course of antibiotics (ie, penicillin-based antimicrobial).