Conditions: Cholesteatoma

Cholesteatoma is a serious condition involving the ear which, if untreated, can progress to cause hearing loss, ear infection, vertigo, or brain infection. Although it is not a cancer, it behaves aggressively: it slowly grows and can destroy nearby bone. The only reliable treatment is surgery to remove it.

What causes cholesteatoma?

There are two main types.

Congenital cholesteatoma is present at birth. It accounts for only about 2 to 5 percent of cases and is thought to arise from a small nest of skin cells that gets trapped behind the eardrum as the ear forms before birth. It usually appears as a white "pearl" behind an intact eardrum in a young child (average age around 5 to 6 years) who has never had ear infections or ear surgery.

Acquired cholesteatoma is far more common (roughly 70 to 95 percent of cases) and develops later in life. Most acquired cholesteatomas are linked to a poorly functioning Eustachian tube — the small channel that connects the middle ear to the back of the nose and normally keeps the air pressure balanced. When this tube does not work well, a vacuum forms behind the eardrum and slowly pulls part of it inward, creating a pocket where dead skin cells collect. Long-standing middle ear infections and a history of chronic ear problems also contribute. Less often, skin can grow into the middle ear through a hole in the eardrum caused by infection, injury, or previous surgery.

It is important to know that most people with Eustachian tube dysfunction or ear infections never develop a cholesteatoma. There also appears to be a family tendency in some cases: having a close relative with cholesteatoma modestly raises the risk, and a small number of people develop it in both ears.

Cholesteatoma and hearing loss

Because of the destruction of normal anatomy, a cholesteatoma is often associated with hearing loss, especially if it is large. In fact, hearing loss is the most common problem caused by cholesteatoma, affecting roughly three out of four people with the condition. A small cholesteatoma may not yet cause hearing loss. On occasion, when a cholesteatoma has eroded into the bones of the middle ear but is positioned such that the solid mass of cholesteatoma transmits sound waves in place of the eroded bones, hearing loss may not be present. Most of the time the hearing loss is the "conductive" type, meaning sound cannot pass efficiently through the damaged eardrum and ear bones. Less commonly, the inner ear itself can be affected, causing a "nerve" (sensorineural) hearing loss that may not be fully reversible even after surgery.

cholesteatoma and infection

Since the space behind the eardrum is not sterile, and since a cholesteatoma consists of dead skin cells, ear infection commonly sets in. Cholesteatomas frequently contain bacteria, and an infected cholesteatoma tends to grow faster and destroy more bone. This can make diagnosis of cholesteatoma somewhat difficult at first, since most ear infections are not the result of cholesteatoma. Often, cholesteatoma is identified only after initial treatments for an ear infection fail or if these treatments reduce the amount of infection enough that a better visual exam can be obtained. A cholesteatoma should be suspected when an ear drains for a long time and does not clear despite appropriate antibiotic drops.

What problems can cholesteatoma cause?

When untreated, cholesteatomas progress in size and severity. When very small, the problem may be unnoticed. As it grows and becomes infected, it can cause hearing loss, chronic ear drainage, and destruction of bone within the ear, including the bone separating the ear from the brain. In severe cases, infection from cholesteatoma can spread around or within the brain and may be life-threatening.

The specific problems a cholesteatoma can cause include:

• Erosion of the middle ear bones (ossicles), which happens in a large proportion of cases and is a major reason for hearing loss. The incus (anvil) is the bone most often affected.

• Dizziness or vertigo from erosion into the balance canals of the inner ear (a "labyrinthine fistula"), which occurs in roughly 4 to 10 percent of cases. Dizziness triggered by loud sound or by pressing on the ear can be a warning sign.

• Facial weakness on the same side as the affected ear, because the nerve that moves the face runs through the ear. This is uncommon but serious.

• Spread of infection beyond the ear, including meningitis, a collection of pus in or around the brain (abscess), or a clot in one of the brain's draining veins. These complications are now rare in countries with ready access to care, but they can be life-threatening, which is why cholesteatoma is treated even when symptoms are mild.

How is cholesteatoma diagnosed?

Cholesteatoma may be diagnosed by physical examination (looking in the ear, often with a microscope or a small endoscope), but not all cholesteatomas are visible this way. Suspicion for cholesteatoma is increased by the presence of a beefy red type of tissue called granulation tissue near the tympanic membrane (eardrum), an ear that is chronically draining fluid, and a history of cholesteatoma, even if treated previously. A CT (computed tomography) scan of the temporal bone (ear and inner ear) is often used to map how far the cholesteatoma has spread and which structures are involved, which helps plan surgery. A CT scan shows bone in fine detail but cannot always tell cholesteatoma apart from fluid, scar, or infection.

When the diagnosis is uncertain, or to check for cholesteatoma coming back after surgery, a special type of MRI scan called non–echo-planar diffusion-weighted imaging (non-EPI DWI) is very useful. Cholesteatoma has a distinctive appearance on this scan, which can reliably distinguish it from scar tissue or fluid. This type of MRI has largely replaced the older practice of routinely re-operating (a "second-look" operation) simply to check whether any cholesteatoma remained. A hearing test (audiogram) is also performed to measure the effect on hearing.

How is cholesteatoma treated?

In almost all cases, cholesteatoma is treated by surgical removal. Reconstructing the structures damaged by the cholesteatoma, such as the eardrum, the bones of the middle ear or the barrier between the cranial vault and the mastoid, may also need to be performed, though this is often done in a separate setting when the surgeon is sure that all of the cholesteatoma has been removed.