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Cholesteatoma: skin behind the ear drum

 

What is cholesteatoma?

 

Cholesteatoma is the presence of skin in the middle ear space behind the ear drum. Usually, the tissue behind the ear drum is a mucous lining like inside the nose, rather than skin. The problem with skin is that it sheds all the time. If you get skin behind the ear drum, this sheds but has nowhere to go because it is stuck in the small middle ear cavity. Over time it grows and gets infected. The pressure from it growing can damage the hearing mechanism, or grow into the bone of the skull right behind the ear (called the ‘mastoid’ bone).

 

Because it has an “–oma” in its name, people often ask if it's a tumour. In fact it is not. When it first got it’s name, people thought it was a tumour, but we now know that it is not. It is just like normal skin, only in the wrong place.

 

What problems does cholesteatoma cause?

 

Usually it causes a smelly discharge from the ear.

 

It’s quite tricky for doctors to diagnose! When we see a child with an ear full of discharge, it is often difficult to know what is going on underneath the discharge. Cholesteatoma is rare, but acute middle ear infections and infected perforated ear drums are common. Quite often it takes a while for it to be diagnosed. What makes us think of cholesteatoma is the fact that the ear has been leaking smelly fluid for a long time, so the flip side of that is that we usually don't find the diagnosis until the problem has been going on for a long time. Unlike a lot of other infections that get better, cholesteatoma usually continues to discharge despite antibiotics, or only settles very briefly.

 

So if your child has a discharging ear that just isn’t settling, cholesteatoma is something to think about. In practice though, other causes of a discharging ear are much more common.

 

Cholesteatoma usually causes discharge and hearing loss. It can also cause tinnitus, balance problems, and rarely even brain abscesses if the infection has gone from the ear to the brain.

 

What tests will be done?

 

Your ENT doctor may wish to use a mini-hoover to suction the discharge from your child’s ear. This is only possible if the child is old enough to sit still to tolerate the procedure. If it is not possible to clear the discharge to know what is going on, the doctor may recommend an examination under general anaesthetic. In this, the child will be asleep under general anaesthetic, allowing the doctor to remove the discharge and find out why it is happening.

 

A hearing test will probably also be done. Your doctor may also recommend a CT scan or an MRI scan to help make the diagnosis.

 

What causes cholesteatoma?

 

Good question! Rarely, cholesteatoma may have been present at birth, but usually it develops during childhood. The Eustachian tube is probably to blame here. The normal Eustachian tube should equalise the pressure behind the eardrum and allows fluid in the middle ear to drain. This mechanism doesn’t function well in children. As a result, negative pressure develops behind the ear drum, and over time this pulls the eardrum inwards, into the middle ear. When the ear drum is pulled inwards, this is called retraction, or a retracted ear drum, or a retraction pocket. If this gets even worse, some skin cells from the outside of the ear drum get pulled into the middle ear, or skin cells get trapped in a little crevice / pocket created by the retraction. This trapped skin in the middle ear is the cholesteatoma.

 

How is cholesteatoma treated?

 

Cholesteatoma can be treated with an operation called mastoidectomy. The mastoid is the bone around the middle ear where the cholesteatoma is. Surgery removes the cholesteatoma, and any infection in the mastoid bone around the cholesteatoma. Cholesteatoma cannot be cured without surgery.

 

Mastoidectomy is carried out under general anaesthetic and can take between 3 and 4 hours. Even after the operation there is a chance that it can come back, hence, we need to see you for regular follow up appointments. Additional revision surgeries and MRI scans to check the ear are often also needed to check that the cholesteatoma has not regrown. The important thing to note is that treatment isn’t an operation and that’s it, it’s surgery and quite a lot of aftercare as well.

 

After the surgery your child will likely go home the same day of the surgery. Often there is a dressing left in the ear after surgery to protect the operated area; this dressing may need to be removed in clinic, or sometimes it is of dissolvable type. There may be some discharge through the dressing for several days after the operation; this is normal. Your child is likely to need antibiotic drops at some stage within a month after surgery, to help the area settle down.

 

There are some risks to be aware of, but remember that majority of the time all goes well. Risks of surgery include bleeding, infection, weakness of the nerve that moves the face, problems tasting food (the nerves of taste and face both run through the middle ear), ringing in the ear  (tinnitus), dizziness, or worse hearing.

 

Regarding hearing, often this is down before surgery, but sometimes it can be even worse after surgery. On occasion, cholesteatoma is found to be wrapped around the bones of hearing, so that the surgeon may have to remove one of the bones of hearing (usually the middle one, the incus), in order to completely remove the cholesteatoma. If the hearing is a problem, hearing aids can be used, and sometimes surgery to restore it may be possible.

 

Sometimes, the surgeons find that cholesteatoma is extensive, or they cannot be sure whether all has been removed; if that happens, they may recommend a second operation to remove the remainder.

 

Don't go swimming until the doctor has told you it is OK to do so.

 

Combined approach tympanoplasty, inside-out surgery, outside-in surgery

 

You may read about combined approach tympanoplasty, inside-out surgery, outside-in surgery, and endoscopic ear surgery. These are different ways of carrying out cholesteatoma surgery. For the most part, all achieve good results. What matters the most is that you have a surgeon who is an expert at their craft, irrespective of exactly how they achieve their good results.

 

Broadly speaking, there are two ways of dealing with cholesteatoma.

 

The first is to enlarge the ear canal and middle ear cavity, and create what is called a mastoid cavity. Usually, only one operation is required. However, because the inside of the ear has been converted into a cavity, that may mean that your child will be more prone to wax build up, cavity infection, and may have to take life-long precautions against getting water into the ear. So although you only need one operation, regular visits to ENT for ear cleaning may well be required.

 

The other option is to avoid creating a cavity. This means that there are no problems with wax or swimming. But because there is no cavity, the surgeon cannot be sure that all cholesteatoma has been removed. So that means that often multiple surgeries will be required before the surgeon is happy that all cholesteatoma is gone. Recently, we have been using MRI scans more and more as a means of diagnosing recurrence of cholesteatoma, so you may find that repeat surgery is replaced with check MRI scans in the future.

 

Not all patients are suitable for either method, but some patients are, and your surgeon may discuss options with you. If you have a specific question, please do talk to your surgeon. Remember, what matters above else is having a surgeon who is an expert at the surgery, whatever method they employ.

 

Long-term cholesteatoma care

 

We have already said that cholesteatoma surgery will need long term care. Make sure that you attend follow up appointments, and report any problems that your child experiences. If there is ear discharge, antibiotic drops or sprays from your GP are usually the initial management. Most hospitals will also have specialist nurses who will be experts in looking after children with mastoid surgery. It is worth getting to know them, and having their number so you can call up if you have problems.

Section contributor:

Mitra Mummadi MRCS

ENT registrar