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Cholesteatoma is defined broadly as a cyst or growth of skin-like material in an abnormal position, such as in the middle ear and /or mastoid region. Technically it is an abnormal accumulation of keratin-producing squamous epithelium. When present, it is a mass exhibiting independent growth, which replaces the middle ear mucous membrane, and destroys the bones in the middle ear and mastoid by producing various enzymes that result in reabsorption of mastoid or middle ear bones. Although it is a benign growth, it can be slow growing and potentially dangerous to the patient.
Cholesteatomas may be classified into two general categories: congenital (i.e. present at birth) or acquired.
Congenital cholesteatomas are thought to arise from embryonal parts of surface skin cells, which become trapped behind the eardrum or in the mastoid as the fetus develops. They are seen behind an intact tympanic membrane, without continuity to the external ear canal and in the absence of other factors such as a prior tympanic membrane perforation or history of ear infections. Two thirds of the cases are confined to the anterior superior portion of the middle ear.
Acquired cholesteatomas can be further divided into primary and secondary acquired. With primary acquired cholesteatomas, the cause is due to underlying Eustachian tube dysfunction resulting in retraction of the top and most thin portion of the ear drum, called the pars flaccida. As a result of negative pressure in the middle ear, the thinnest portion of the ear drum (e.g. pars flaccida) gets pulled inward into the mastoid area (called the epitympanic area) and forms a “retraction pocket”. Once a retraction pocket develops, the normal migratory pattern of the tympanic membrane epithelium is altered, encouraging the accumulation of keratin, or desquamated skin. If not addressed, the sac slowly enlarges, destroying more bone and destroying a portion of the ossicles, which result in a conductive hearing loss. Secondary acquired cholesteatoma usually occurs because skin (e.g. squamous epithelium) becomes implanted in the middle ear as a result of ear drum perforations, ear surgery, foreign body placement (ventilating tubes), or trauma to the ear which allows skin to migrate into the middle ear or mastoid area.
Cholesteatoma Symptoms
Initially, the ear may drain, sometimes with a foul odor. As the cholesteatoma pouch or sac enlarges, it can cause a full feeling or pressure in the ear, along with hearing loss. Dizziness, or muscle weakness on one side of the face (the side of the infected ear) can also occur.
History - A careful otologic history should be obtained in order to elicit the early symptoms of cholesteatoma. The most common presenting symptoms are hearing loss, otorrhea, otalgia, tinnitus and vertigo. A previous history of eustachian tube problems, middle ear disease, such as chronic otitis media and/or a tympanic membrane perforation may be evident. A progressive unilateral hearing loss with a chronic foul smelling otorrhea is suspicious for a cholesteatoma.
Physical Examination - In addition to a thorough head and neck examination, particular attention should be pain to the otologic exam. Otomicroscopy is most important in evaluating the presence of cholesteatoma and extent of disease. The ear should be thoroughly cleaned of any discharge and debris. A retraction pocket may be seen, often in the pars flaccida area or postero-superior quadrant of the eardrum. Accumulation of squamous debris may occur within the retracted pocket. Granulation tissue may be present from the diseased infected bone in the region of the pars flaccida (top of eardrum area) or posterior bony canal wall near the eardrum edge. When extensive, a polyp may protrude through a defect at the top of the ear drum area. Extreme caution should be used with polyp removal, as it may be adherent to important underlying structures such as the ossicles or facial nerve. Pneumatic otoscopy should be performed in every patient with a cholesteatoma. A positive fistula response suggests erosion of the semicircular canals or cochlea.
Is It Dangerous?
Ear cholesteatomas can be dangerous and should never be ignored. Bone erosion can cause the infection to spread into the surrounding areas, including the inner ear and brain. If untreated, deafness in the affected ear, dizziness, brain abscess, meningitis, facial muscle paralysis, and rarely death can occur.
Inspection of the ear using a microscope is required to clearly visualize the eardrum, canal, middle ear, or epitympanic area of the mastoid region. Inspection is the most important aspect of making the diagnosis. A CAT scan will help to determine the extent of the cholesteatoma growth and what structures are involved. It often is not routinely ordered unless there is a complication associated with the chronic ear disease, such as dizziness, or if a sensorineural hearing loss or facial weakness exists.
Diagnostic Tests
Audiology - Audiologic testing helps to determine the presence and extent of hearing loss. Pure tone audiometry with air and bone conduction, speech reception thresholds, and word recognition usually reveal a conductive hearing loss in the affected ear. The degree of conductive loss will vary considerably depending on the extent of disease. A moderate conductive deficit in excess of 40 dB indicates ossicular discontinuity, usually from erosion of the long process of the incus. A mild conductive deafness may be present with extensive disease if the cholesteatoma sac transmits sound directly to the stapes or footplate. Tympanometry results will vary and may suggest decreased compliance or perforation of the tympanic membrane.
Imaging - Preoperative imaging with CT of the temporal bones allows pre-operative imaging of anatomy, provides evidence of the extent of the disease, and used generally for complications associated with the cholesteatoma. However, it generally is not used as an essential aid to planning surgery in uncomplicated cases of cholesteatoma. Temporal bone CT scans should be obtained for revision cases when complications of surgery occur.
Treatments for Cholesteatoma
Initial treatment may consist of a careful cleaning of the ear, antibiotics, and ear drops. Therapy is aimed at eliminating drainage, granulation tissue or polyps in the ear.
The only known treatment for cholesteatoma is removal of the cyst. Cholesteatomas usually continue to grow if not removed. Surgical treatment is effective, but there may be a need for periodic cleaning or repeat surgery if the cholesteatoma recurs. There are 3 goals with the first being total eradication of the cholesteatoma to obtain a safe, dry ear. The second objective is restoration or maintaining the hearing. The third objective is to maintain a normal anatomic appearance of the ear if possible. Management of complications when they arise takes priority over other objectives. The surgical procedure to be used should be designed for each individual case according to the pathology present. The extent of disease often will determine the surgical approach.
Medical management, including thorough cleaning of the ear may exteriorize and safely decompress the accumulating keratin debris. This may be a valid management strategy for patients in whom anesthesia poses an unacceptable risk. Such management is not recommended in children. Preoperatively, it is very important to eliminate drainage and any acute inflammatory changes. This will reduce troublesome intraoperative bleeding and help identify disease that must be removed from other important structures.
Most cholesteatomas usually require surgical treatment. Surgery is performed under general anesthesia in most cases. Reconstruction of the hearing mechanism is not always possible in one operation; and therefore, a second operation may be performed six to twelve months later. The second operation will attempt to restore hearing and, at the same time, inspect the middle ear space and mastoid for any residual cholesteatoma.
Admission to the hospital is usually done the morning of surgery, and if the surgery is performed early in the morning, discharge usually occurs the same day. In cases of a serious infection or complications, prolonged hospitalization for antibiotic treatment may be necessary.
Follow-up office visits after surgical treatment are necessary and important, because cholesteatoma can sometimes re-occur. In cases where an open mastoidectomy cavity has been created, office visits at least annually are needed in order to clean out the mastoid cavity and prevent new infections. In these patients, there must be lifelong periodic ear examinations.
Tympanoplasty
Removal of cholesteatoma from the middle ear requires a tympanoplasty procedure. Most often a perforation is present, which also requires repair. When a tympanoplasty is performed with repair of a perforation either a lateral graft technique or medial graft technique is utilized. Each technique has its own advantages and disadvantages. The lateral graft technique provides excellent visualization of the middle ear structures, but requires more experience.
Tympanoplasty with Ossiculoplasty
This is the operation performed to repair both the sound transmitting mechanism and any perforation of the eardrum, while removing any disease in the middle ear. Cholesteatomas may damage one or all three of the bones in the middle ear that transmit sound from the eardrum to the inner ear. The perforation is repaired with fascia from the muscle above the ear. The ossicles are repaired with the use of artificial prostheses, called PORPs (partial ossicular replacement prostheses) and TORPs (total ossicular prostheses). A PORP is used when the stapes is still present and a TORP is used when all the normal bones in the middle are absent. In some instances this requires a “staged procedure” (i.e. the tympanoplasty is performed first and 6-12 months later the ossiculoplasty is completed).
Tympanoplasty with Mastoidectomy Procedures
Often the disease involves or extends into the mastoid cavity and an additional mastoid procedure is required. The types of surgery for cholesteatoma involving the mastoid are:
Canal-wall-down (CWD) procedure
This procedure involves taking down the posterior ear canal wall to the facial nerve level, and exteriorizes the mastoid into the external ear canal. The epitympanum is obliterated with removal of the scutum, head of the malleus and incus. A classic CWD operation is the modified radical mastoidectomy in which the middle ear space is preserved. The radical mastoidectomy is a CWD operation in which the middle ear space is eliminated and the eustachian tube plugged. The meatoplasty (i.e. ear opening) should be large enough to allow good aeration of the mastoid cavity and permit easy visualization to facilitate postoperative care and self cleaning. The indications for this approach include:
The advantages of the CWD procedure are that residual disease is easily detected, recurrent disease is rare, and the facial recess is exteriorized. The major disadvantage of this procedure is the open cavity and that mastoid bowl maintenance can be a lifelong problem. Healing takes longer in open cavities and the middle ear is shallow and difficult to reconstruct. Also, it is necessary to keep water out of the ear thereafter.
Intact-canal-wall (ICW) procedure
This procedure consists of preservation of the posterior bony external auditory canal wall during mastoid procedures. A staged procedure is often necessary with a scheduled second look operation at 6 to 12 months for removal of residual cholesteatoma and ossicular chain reconstruction. The procedure should be adapted to the extent of disease as well as the skill of the otologist. This approach may be indicated in patients with a large pneumatized mastoid and a well aerated middle ear space, suggesting good eustachian tube function. Intact canal wall procedures are contraindicated in only hearing ears or in the patient with a labyrinthine fistula.
The advantages of this procedure compared with CWD mastoidectomies are more rapid healing time, less drainage from the ear, easier long-term care, no water precautions necessary and hearing aids should they be needed are easier to fit and wear. The disadvantages associated with this procedure include the difficulty of technique with more operative time generally, residual disease is more difficult to detect, retraction pockets leading to recurrent disease are possible, and staged operations are often necessary.
Transcanal anterior atticotomy
This procedure is indicated for limited cholesteatoma involving the middle ear, ossicular chain, and epitympanum. The atticotomy involves elevation of a tympanomeatal flap with removal of the scutum to the limits of the cholesteatoma. After removal of the disease, the scutum is usually reconstructed with cartilage.
Modified radical mastoidectomy
It is indicated for mastoid cholesteatoma that does not involve the middle ear space and is lateral to the ossicles. Preferably, the mastoid should be poorly developed for creation of a small cavity. The eustachian tube function should be adequate, with an intact pars tensa and aerated middle ear space. The modified radical procedure is like the radical mastoidectomy, with the exception that the middle ear space is not entered.
Radical mastoidectomy
This procedure is done to eliminate middle ear and mastoid disease. It involves the removal of the eardrum, malleus, incus, posterior canal wall and the eustachian tube is plugged. A large common cavity is created between the middle ear and mastoid. The indications generally include:
Possible surgical complications include, but are not limit to: deafness in one ear, dizziness, persistent ear drainage, erosion into the facial nerve (causing facial paralysis), leakage of cerebral spinal fluid, labyrinthitis – inflammation of the inner ear, vertigo, meningitis, and brain abscess.
Conductive hearing loss is a common complication of cholesteatoma as ossicular chain erosion occurs. Erosion of the incus and/or stapes superstructure may produce a conductive hearing loss as high as 60dB. Evidence of sensorineural hearing loss may indicate involvement of the inner ear. On rare occasions there is a total loss of hearing in the operated ear.
A labyrinthine fistula is an infrequent complication of a cholesteatoma. It is an abnormal opening into the inner ear, and results from enzymatic absorption of the bone. A fistula should be suspected in a patient with longstanding disease with sensorineural hearing loss and/or vertigo caused by loud noise or pressure changes in the middle ear. Absence of a positive fistula test does not rule out this complication. A high resolution CT scan of the temporal bone will help to determine the presence of a fistula. The most common site is the horizontal semicircular canal, although the basal turn of the cochlea is also at risk. The procedure of choice with this complication has been the modified radical mastoidectomy, as discussed previously. Management of the matrix overlying the fistula depends on the infection status of the ear, degree of hearing loss in the affected and nonaffected ear, size, location of the fistula, and surgeon’s experience. In an only hearing ear, matrix should always be left intact over the fistula. The cholesteatoma matrix should be left over large fistulae of the vestibule or cochlea if hearing is normal. Sometimes leaving the matrix over a small fistula and returning within 6-9 months for the second “staged” procedure enables the cholesteatoma to then be removed more safely, as the ear is more dry and healthy appearing. The status of the hearing in the opposite ear should always be considered however when encountering a fistula, regardless of the size.
Facial paralysis in patients with cholesteatoma requires immediate surgery. The paralysis may develop acutely following infection or slowly from chronic expansion of the cholesteatoma. A CT scan of the temporal bone is required which helps localize the involvement. The most common site is the geniculate ganglion from disease in the anterior epitympanum.
A simple mastoidectomy with facial recess approach will expose the tympanic and mastoid portions of the facial nerve, while a middle fossa approach is required with involvement of the petrous apex. Removal of cholesteatoma and infected material with decompression of the nerve usually suffices. Administration of intravenous antibiotics and high-dose steroids are also helpful. Injury to the nerve during surgery should be immediately repaired with decompression of the nerve proximal and distal to the site of injury.
Intracranial complications of cholesteatoma are potentially life-threatening. Infections such as a periosteal abscess, lateral sinus thrombosis, and intracranial abscess occur in less than 1% of all cholesteatomas. Findings suggesting an impending intracranial complication include suppurative malodorous otorrhea, usually chronic with headache, pain and/or fever. The presence of mental status changes with neck stiffness or other cranial nerve involvement requires neurosurgical consultation with urgent intervention. Epidural abscess, subdural empyema, meningitis and cerebral abscesses should be treated immediately prior to definitive otologic management of ear disease.