Published: Feb. 15, 2010
Updated: Feb. 15, 2010
A cholesteatoma is a benign growth of skin in an abnormal location such as the middle ear or base of skull.
Normally, skin lines the entire ear canal and outer surface of the eardrum. The outermost layer of skin is composed of dead cells which are being sloughed off and expelled from the ear canal with ear wax. A major component of these dead cells is a protein called keratin.
In cases of severe Eustachian tube (ET) dysfunction, the eardrum can be retracted inward because of negative pressure in the middle ear space. The place where the eardrum is most easily retracted is the top portion, which is the most flaccid (thin) portion of the eardrum.
When the eardrum is retracted, skin cells continue to slough, but cannot be expelled from the ear canal in the usual way. Debris accumulates in the middle ear, usually surrounding the middle ear bones. Over time, the accumulation of debris continues to grow, and as it does it produces enzymes that cause destruction of bone in the middle ear.
When caught at an early stage, erosion of the middle ear bones can cause conductive hearing loss, usually accompanied by infections and ear drainage.
In more advanced stages (uncommon), cholesteatomas can erode bone of the inner ear causing sensorineural hearing loss, bone overlying the facial nerve, causing facial weakness, and bone of the skull base, causing (in advanced cases) brain abscess and meningitis.
Most cholesteatomas are acquired as described above, but some can be due to a problem with development of the ear, and present from birth (congenital cholesteatoma). These cases usually present with hearing loss alone, without a history of ear infections.
Almost all cholesteatomas warrant surgical treatment. The primary goal of surgery is to eliminate the disease which can continue to cause infections and other complications until eradicated. The secondary goal is to restore hearing.
Surgery is most commonly done in two stages, the first to remove the cholesteatoma and the ‘second look’ to insure that the disease has been entirely removed and not recurred and to reconstruct the middle ear to improve hearing.
In cases of extensive disease, the posterior (back) wall of the ear canal may be removed to create a mastoid cavity, which exteriorizes the ear -- preventing trapping of keratin debris -- and allows for optimal management of the cholesteatoma.
The surgical procedure is called a tympanomastoidectomy.