Cholesteatoma & mastoidectomy
What is cholesteatoma?
Cholesteatoma (pronounced: koh-less-tee-ah-toe-mah) is a slow-growing, abnormal skin cyst within the middle ear.
What causes it?
In a healthy ear, dead skin in the ear canal should shed and migrate outwards where it mixes with other substances to form ear wax. A cholesteatoma is caused when this dead skin migrates into the middle ear instead where it then gets trapped and forms a cyst. It is usually caused by a problem with the ear drum, which separates the ear canal from the middle ear. This can be in the form of either a retraction pocketof the ear drum that collects the dead skin and drags it inwards, or a hole in the ear drum that allows the dead skin to migrate through it. As more and more dead skin collects, the cholesteatoma grows in size and spreads from the middle ear into the mastoid bonebehind the ear.
What are the symptoms?
People with a cholesteatoma usually go to their GP because of a leaking ear, hearing loss or both. There may also be bleeding from the ear due to the formation of a polyp around the cholesteatoma (a polyp is proud flesh that occurs as a result of the chronic drainage from the ear). Sometimes they may also have dizziness and pain, although pain is not a usual symptom of cholesteatoma. Very rarely, a patient will have weakness of the face as a first sign of cholesteatoma.
How is it diagnosed?
It is usually diagnosed by an ENT specialist after examining inside the ear with an otoscope or under the microscope. Oftentimes the ear must be cleaned of pus and debris before the ear drum can be properly examined. A hearing test is usually performed in the ENT clinic to assess whether hearing has been affected by the cholesteatoma. A CT scan of the ear will also be ordered to give more information about how large the cholesteatoma is, how far it has extended into the middle ear and the mastoid bone and what structures it has eroded. A CT scan also acts as a road map for the surgeon if surgery is planned.
What kinds of problems can a cholesteatoma cause?
Cholesteatoma can lead to several problems, from the troublesome to the potentially dangerous. This is because of its erosive nature, meaning that it can erode the surrounding bone and structures of the middle and inner ear, thus providing more room for it to expand into.
Problems that a cholesteatoma can cause include:
Because a cholesteatoma is made up of dead skin, it acts as a good breeding ground for bacteria. This results in chronic ear infections (known as chronic otitis media) which can cause recurrent or constant foul-smelling leakage from the ear. Less commonly, infections can sometimes result in a collection of pus (an abscess) in the mastoid bone, face, neck or even the brain where it can cause serious complications.
Toxins from bacteria can get into the inner ear where they can result in permanent sensorineural hearing loss. Exposure of the hearing bones (the ossicles) to constant infections can cause the bones to disintegrate, resulting in a conductive hearing loss. The cholesteatoma itself can erode the ossicles, also causing a conductive hearing loss or into the cochlea causing a sensorineural hearing loss.
If the cholesteatoma erodes into the vestibular system of the inner ear, it can result in a fistula (an abnormal opening) that can cause dizziness or episodes of vertigo (the sensation of spinning). This is usually a late complication of a cholesteatoma that has been present for a long time.
The facial nerve controls the muscles of the face and allows them to move. There is one on either side controlling each half of the face. The nerve comes from the brain and passes through the ear before it reaches the face. It is protected by bone in most people but in about 10% of the normal population it is not. A cholesteatoma can sometimes erode the bone covering the facial nerve and cause it to be come inflamed or destroy it altogether. This can result in a weakness of the face causing it to droop like in someone who has had a stroke. It may be temporary or even permanent. It is usually a late complication of cholesteatoma.
How is it treated?
The definitive treatment for cholesteatoma is surgery and it is recommended that all cases of cholesteatoma be treated where possible to prevent potential complications of the disease. The surgery performed is called a mastoidectomy, during which the mastoid bone is drilled open to remove the cholesteatoma. During mastoidectomy, the ear drum is also repaired to prevent recurrence of the cholesteatoma (called a tympanoplasty) and an attempt is made to restore hearing, if possible, at the same time (called an ossiculoplasty). Mr Trinidade usually performs these three procedures together, when it is known as a tympanomastoidectomy and ossiculoplasty.
Occasionally only a tympanomastoidectomy is performed first and then an ossiculoplasty performed as a second surgery later on (see below).
In patients who are not fit enough for a general anaesthetic, a cholesteatoma can be managed in the clinic by regular cleaning of the ear under the microscope, but this is not ideal, especially in large cholesteatomas.
What is the mastoid bone?
The mastoid bone is the part of your skull that you can feel behind your ear. It is connected to the middle ear in front of it and is thought to act like a small lung to it. The middle ear and mastoid bone can be considered as two parts of the same system and both are ventilated through the Eustachian tube, the tube that connects your nose through your ear (you use this tube to pop your ears).
How is a mastoidectomy for cholesteatoma performed?
Mastoidectomy is usually performed under a general anaesthetic. To get access to the ear drum, a cut is made behind the ear (a post-auricular approach). The mastoid bone is then drilled open to expose the cholesteatoma. There are many ways to do this. Mr Trinidade performs this by starting from the front, where the mastoid bone joins the middle ear, backwards to the furthest point that the cholesteatoma extends into the mastoid bone from the middle ear. In this way, only as much bone that needs to be removed to expose the cholesteatoma is removed and no more. This is known as a front-to-back approach. A cavity in the mastoid bone is created by drilling it open and then removing the cholesteatoma.
Once the cholesteatoma has been removed, a tympanoplasty and ossiculoplasty are performed for reasons explained above. Finally, the cavity formed during the mastoidectomy is closed off with cartilage harvested from around the ear.
At the end of the operation, the ear canal is packed with an ear wick (a non-dissolvable dressing) near the entrance. The wound behind the ear is then stitched close using dissolvable sutures. A head bandage is usually applied.
The facial nerve, which passes through the ear on its way to supply the muscles of the face, is monitored in all cases with a facial nerve monitor. This helps to protect the facial nerve from injury. To do this, tiny needles are placed above the eye, at the corner of the mouth and on the chest. These are removed at the end of the operation and you may feel some short-lived discomfort or develop bruising in these areas. Mr Trinidade does not generally shave hair for this procedure.
The ear may stick out for a couple of weeks but this will return to normal once the swelling subsides and a scar forms.
What are the risks of mastoidectomy?
Mastoidectomy is a common operation with minimal risks, but as with all operations, there are risks that you need to be aware of. These include:
Bleeding and infection
As with any operation, these are standard risks. Bleeding is usually in the form of an ooze, which settles within the first 24 hours. Sometimes, there is significant bleeding that collects under the skin forming a haematoma. This usually needs to be evacuated with a small procedure. Infection may cause redness and swelling around the wound site or show as drainage from the ear canal. Oral and topical antibiotics may be required.
The taste nerve runs along the back of the ear drum and must often be cut to allow for full access to the cholesteatoma. This results in an abnormal taste in the mouth, usually salty or metallic, or may make certain foods taste strange. It is usually temporary and resolves after several weeks or months.
Any ear operation has the risk of worsened hearing. This risk of this in mastoidectomy is about 5 to 10%. Often the hearing loss is due to fluid or blood collection within the middle ear during the healing phase and can take up to about 3 months to resolve. Sometimes the cholesteatoma itself acts as a means of sound transmission to the inner ear by virtue of its size, so when it is removed during surgery, hearing can drop. The hearing bones also often have to be removed to allow access to the cholesteatoma, which can also cause a hearing loss. In both cases, an ossiculoplasty can usually restore this loss.
In less than 1% of cases, the facial nerve is injured. This may lead to a partial or full weakness of the face that very rarely is permanent. The use of a facial nerve monitor helps to avoid this risk.
About 2-3% of patients will experience some tinnitus (ringing in the ear) following surgery. This is usually temporary and resolves with time. In some people it is persistent, but the majority of people are able to ignore it without it becoming bothersome.
What is the aftercare following mastoidectomy?
After surgery, you will have a wick within the ear and will therefore not be able to hear very well from that ear. If you have had a head bandage applied, this can be taken off at home the following morning. This will often be blood-stained and is normal. Take regular pain medicine for the first 2 to 3 days, or longer if needed. If you stopped aspirin before the operation, this can be restarted the day after surgery.
Do not wash your hair for 2 days, after which you may do so, but you must not get water inside the ear. The best way to protect the ear from getting wet is to place a cotton ball smeared in Vaseline into the bowl of the ear during showering/bathing (click here to see how). Apply antibiotic ointment to the wound twice daily for 1 week.
Your first follow up with Mr Trinidade will be in 2 weeks. Two days before your appointment, start applying ear drops to your ear (you will be supplied with this before leaving the hospital). This will help to soften the wick so that it can be easily removed in the clinic. If your wick has come out before this time, do not worry. Just start using the ear drops as prescribed and keep water out of it.
At the clinic, your wound will be inspected and the ear wick will be removed. This can sometimes be uncomfortable but is usually straightforward and takes less than a minute to do. Once the wick is out, you will be asked to continue ear drops for a further week. As the stitches are dissolvable, they will not need to be removed in the clinic.
You can start showering/bathing without cotton wool protection at 4 to 6 weeks after the operation. You are encouraged to start gently popping your ears by pinching your nose and blowing out (called a Valsalva manoeuvre; click here to see how to perform one) after 6 weeks. Your second visit to the ENT clinic will be in approximately 3 months after the operation when a hearing test will be performed.
Any signs of infection (pain, swelling, drainage, fever) should be reported to your GP or to the ENT clinic. Flying and diving should be avoided for 6 to 8 weeks after the operation. Mr Trinidade advises that you have your ear checked prior to resuming diving.
Can cholesteatoma come back once it is removed?
Yes. Mastoidectomy performed using the front-to-back approach has a failure rate of about 3 to 6% (based on research Mr Trinidade has conducted). This may be as a result of skin cells from the cholesteatoma being left behind due to them not being visible with the naked eye or under the microscope, or due to difficult access to the disease at the time of surgery. Sometimes another retraction pocket can form in the ear drum, forming an entirely new cholesteatoma.
For these reasons, it is sometimes recommended that patients who have a mastoidectomy for cholesteatoma undergo a second procedure 1 year later, where the ear is once again opened under a general anaesthetic to look for any residual or recurrent cholesteatoma. This is known as a second-look procedure. A CT scan or a special type of MRI scan of the ear can be performed to look for residual cholesteatoma instead of a second surgery, but is not 100% accurate and the decision to perform a scan instead of a second-look procedure is usually decided on a case-by-case basis.
Occasionally, if a very large cholesteatoma is found at the time of the initial surgery or if removal of the cholesteatoma proved to be difficult, then an ossiculoplasty will not be done at the time and instead performed during the second-look procedure in a year's time. In the meantime, a hearing aid can be used.
Read more about tympanoplasty here.
Read more about harvesting cartilage from around the ear here.
Read more about ossiculoplasty here.
Read more about ear drum retraction pockets here.
A diagram showing how a cholesteatoma forms. Dead skin from the ear canal collects within the middle ear causing a cyst instead of natrually moving outwards to form wax. A retracted or perforated ear drum facilitates this.
A large perforation of the ear drum with most of the ear drum missing. A cholesteatoma can be seen forming behind it in the upper part of the picture after dead skin has migrated through. In the lower part, pus from chronic infection can be seen as a result of the cholesteatoma.
The top part of the ear drum has collapsed inwards forming a retraction pocket. This pocket can be seen here collecting dead skin which has formed a cholesteatoma. This will continue to expand as more dead skin collects and erode the surrounding bone and middle ear structures
A normal ear drum
A diagram showing how a cholesteatoma gradually expands over time, eroding evrything in its path, including surrounding bone, and middle ear structures.
In this picture of the skull, the mastoid bone is shaded red, and is part of the temporal bone (shaded blue), which contains the deep structures of the ear. The mastoid bone lies just behind the ear canal.
This diagram shows the close relationship between the mastoid bone, the middle ear and the middle ear structures, including the facial nerve and the ossicles.