Cholesteatoma and Hearing Loss
Cholesteatoma is growth of keratinizing squamous epithelium in the mastoid process and/or middle ear. These growths are destructive and expanding. Even though these growths are not cancerous, they can still create significant problems because they are erosive and expansive. Cholesteatoma causes destruction of the ossicles and also sometime spreads into the brain (via skull base). Cholesteatoma is often infected which causes chronically draining ears. Cholesteatoma can be classified as:
- Congenital cholesteatoma: Congenital cholesteatoma happens when squamous epithelium cells get trapped within the temporal bone when embryo forms and develops (also known as embryogenesis). Once expanded, cholesteatoma causes conductive hearing loss either by obstructing Eustachian tube or by surrounding the ossicular chain.
- Primary acquired cholesteatoma: The precise reason for primary acquired cholesteatoma is not certain but it is believed that a dysfunction of the Eustachian tube creates constant negative pressure in middle ear, which make tympanic membrane to be 'sucked back' and retract. Due to continuous sucking back and retracting of tympanic membrane, the lateral wall of the epitympanum (upper portion of the tympanic cavity which contains the body of the incus and the head of the malleus) erodes, which produces a slowly expanding defect. This process results in forming of a pocket which is lined by squamous epithelium. Mostly this erosions goes on and as the ball of epithelium grows, it surrounds the ossicles and sometime also reaches mastoid bone and middle ear.
- Secondary acquired cholesteatoma: This arises as a result of hurt to the tympanic membrane, such as during surgical manipulation of the eardrum or during treatment of acute otitis media or trauma/brain injury. Sometime squamous epithelium may be accidentally introduced during other surgical process, which triggers the process of cellular growth causing cholesteatoma formation.
The Ear, Hearing and Cholesteatoma
Cholesteatoma generally develops as pouches or cysts which shed layers of old skin. These old skins are build up in middle ear. Skin can get inside the middle ear by repeated infections/tear or by inward pulling of the eardrum.
The cholesteatoma can grow bigger in size with the passing of time and can destroy the bones inside the middle ear. This destruction of delicate bones inside middle ear can lead to hearing loss (deafness). Surgery can often help with this kind of hearing loss. In rare incidents of cholesteatoma, it can also cause permanent hearing loss.
Generally cholesteatoma occurs due to poor eustachian tube function and/or infection in the middle ear. Normally only one ear is affected by a cholesteatoma. Cholesteatoma can be identified by following two symptomps:
- constant, often smelly, discharge from the affected ear
- progressing loss of hearing in the ear affected with cholesteatoma
Some people who are suffering from cholesteatoma may also feel some minor discomfort or fullness in their ear.
Cholesteatoma can be removed by surgery. Surgery also prevent any further damage to the ear. Antibiotic medication may be given to clear up any infection and make the ear dry, prior to surgery.
Surgery removes all of the affected areas, including the cholesteatoma itself. There are two kind of cholesteatoma surgeries available:
- Tympanomastoidectomy: Under tympanomastoidectomy, tympanic membrane (eardrum) and complete or partial mastoid bone is removed depending on the severity/growth of cholesteatoma. This surgery creates a large cavity (hole) in the inner ear, which requires regular cleaning and de-waxing (removal of earwax). The cleaning and de-waxing is generally done in an ENT clinic. Tympanomastoidectomyis is a preferred surgery for cholesteatoma as this is very successful in removing all of the cholesteatoma. Sometime complications in surgery may results in deafness, damage to facial nerve (which may paralyse the facial muscles in the affected area) and dizziness.
- Tympanoplast: Tympanoplast is a less invasive technique with a better visual (cosmetic) appearance after surgery. However, it is associated with a higher risk of recurrence of cholesteatoma, and a further operation to check is required up to a year later.
Cholesteatoma may also be treated with the help of 'aural toilet'. Aural toilet involves washing out ear canal and sucking (drawing out) bits (debris). This procedure does not prevent/cure cholesteatoma and needs performing regularly.