Cholesteatomas are tumor like growths in the middle ear. They are generally formed from the skin cells on the outside of the eardrum that have become folded into the middle ear (retraction pocket) as a result of ear infections or with a perforation of the eardrum. The squamous epithelium, or skin layer, of the outside of the eardrum is continuously replaced and the old skin elements are meant to come out through the ear canal. When these skin elements become trapped behind the eardrum in the middle ear or mastoid, it is called a cholesteatoma. A cholesteatoma cyst consists of layers of scaly or keratinized (horny) layers of epithelium, which may also contain cholesterol crystals. This cyst typically grows very slowly and begins to cause symptoms as it compresses and erodes the structures of the middle ear and surrounding areas. Often the debris is infected with bacteria or other organisms, causing drainage and foul smell.
Cholesteatomas generally occur as a result of infection, and are called acquired cholesteatoma. These are the most common type of cholesteatoma. This type of cholesteatoma may occur at any age. The other type of cholesteatoma is congenital cholesteatoma, which occurs much less commonly. In this type, skin cells are trapped in the middle ear from birth. These skin cells grow in the middle ear and have no way of coming out of the middle ear cavity because of the intact eardrum. The typical age of presentation for the congenital cholesteatoma is 4-6 years old.
SIGNS AND SYMPTOMS:
Early symptoms of cholesteatoma include hearing loss, mucopurulent (brown/yellow) drainage from the ear, ear bleeding, ear pain, tinnitus and vertigo. A previous history of middle ear disease, such as chronic otitis media and/or eardrum perforation, is usually present.
On examination, a retraction pocket may be seen, often in the upper part of the eardrum. Accumulation of squamous skin debris may occur within the pocket. Granulation tissue (inflammatory tissue) may arise from the diseased infected bone of the ear canal wall. When extensive, a polyp may protrude into the ear canal from the cholesteatoma pocket.
MECHANISM OF DAMAGE
Damage to the middle and inner ear from a cholesteatoma is due to erosion and expansion of the cholesteatoma. This generally occurs gradually over years. If untreated, a cholesteatoma can eat into the three small bones located in the middle ear (the malleus, incus and stapes, collectively called ossicles) and into the inner ear, which can result in nerve deterioration, deafness, imbalance and vertigo. It can also affect and erode, through the enzymes it produces, the thin bone structure that separates the top of the ear from the brain. Erosion of this bone can lead to infections in the brain with serious complications. Cholesteatoma can also cause damage to the facial nerve that runs through the middle ear and supplies the facial muscles. Injury to this nerve from the cholesteatoma can cause facial paralysis.
DIAGNOSIS OF CHOLESTEATOMA
Cholesteatoma is diagnosed with a thorough clinical examination. Any debris is cleared from the ear canal and the eardrum and middle ear are assessed for any evidence of cholesteatoma.
An audiogram, or hearing test, is performed with air and bone conduction, speech reception thresholds, and word recognition. These tests adequately identify any hearing loss. A conductive hearing loss is common with cholesteatoma, usually from erosion of the ossicles causing a defect in the ossicular chain. The extent of the cholesteatoma and erosion of the ossicular chain determines the severity of the hearing loss.
At times, CT scan of the temporal bone may be performed to evaluate the anatomy, which may reveal evidence of the extent of the disease. A CT scan is not essential for evaluation of a cholesteatoma, but may be performed if your surgeon would like further information before definitive treatment
MANAGEMENT OF CHOLESTEATOMAS
Cholesteatoma is treated surgically with a primary goal of total eradication of the disease to obtain a safe and dry ear. The second objective is restoration or maintaining the functional capacity of hearing.
The surgical procedure used is designed for each individual case according to the extent of disease. More extensive disease will usually dictate a more aggressive surgical approach. Surgical treatment is typically broken down into two broad categories:
Intact Canal Wall Mastoidectomy
The mastoid bone behind the ear canal is drilled and all disease is removed from the mastoid cavity in this procedure. In addition, the area around the heads of the hearing bones is inspected and any cholesteatoma disease is cleared using this approach. An intact canal wall mastoidectomy maintains the normal ear canal, and the mastoid cavity cannot be visualized in the office (as it can be with a canal wall down mastoidectomy).
The ossicles in the middle ear cavity may be reconstructed depending on the extent of the cholesteatoma. If there has been erosion of one of the hearing bones, it may be replaced with a synthetic prosthesis to restore hearing to the ear.
Canal-Wall-Down (CWD) Procedure
This procedure involves removing the ear canal wall that separates the ear canal from the mastoid cavity behind it. This procedure creates a large cavity that can be easily examined through the ear canal opening. Thus, all cholesteatoma disease is removed from the ear and the large mastoid cavity is cleaned intermittently in the office. A procedure to enlarge the opening of the ear canal (meatoplasty) is always performed to allow aeration of the mastoid cavity and to permit easy visualization in the office to permit postoperative care and self-cleaning.
The advantages of the CWD procedure are that residual disease is easily detected and recurrent disease is rare. 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 it is more difficult to reconstruct hearing. Dry ear precautions are essential.
Cholesteatoma can cause significant problems when left untreated. Surgery is the mainstay of treatment for this disease process. Long term follow up is critical to ensure that the entire disease process has been eradicated.