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MASTOIDECTOMY

What is the mastoid?

The ear comprises the outer, middle and inner ear (figure 1). The mastoid is a bony prominence located behind the ear. It contains a number of air spaces which connect to the middle ear. 




Figure 1: Diagram of outer, middle and inner ear

When is a mastoid operation required?

Mastoid surgery is performed when infections in the middle ear spread to the mastoid cavity. Commonly a pocket of skin (cholesteatoma, figure 2) develops on the ear drum and may invade the middle ear and subsequently the mastoid. This may cause recurrent ear discharge. The cholesteatoma may also invade the ossicles (3 bones in the ear that are involved in hearing), causing hearing loss. Other important structures like the brain, nerve that supplies the muscles of the face and blood vessels run close by and hence the cholesteatoma must be removed to prevent these structures from being eroded. The operation to do this is known as a mastoidectomy.

Figure 2: Cholesteatoma


Success rates

The chances of obtaining a dry and self cleaning ear are over 80%, but the success rate varies between cases. Often, the hearing is worse after mastoidectomy, since the goal is primarily to eradicate the disease, rather than preserve hearing. However, occasionally the hearing may improve as well. Hearing reconstruction is often delayed because it is necessary to rebuild the bones of hearing at a future date. 


The operation

The operation is usually carried out under a general anaesthetic. Some cholesteatomas which are very small can be removed through the ear canal. Most cholesteatomas require that an incision be made behind or in front of the ear to expose the tumor adequately. The cholesteatoma is completely removed microscopically 
In more extensive cholesteatomas, the disease may have eroded through the bony wall which separates the middle ear from the mastoid. This may require a more radical operation, removing the wall separating the middle ear from the mastoid. The result is a so-called open cavity which requires life-long follow-up in the outpatient clinic, every few months.
In less extensive cholesteatomas, especially when infection is well controlled before surgery, an intact canal wall operation may be the favoured procedure. This operation preserves the wall between the middle ear and mastoid. The principal advantages of the intact canal wall operation are a more normal canal and ear drum, and a greater possibility of hearing restoration. In addition, most patients with the intact canal wall operation can allow water in the ear. The chief disadvantage of the intact canal wall operation is that a regrowth of cholesteatoma may not be evident. Thus, many ear surgeons will delay rebuilding the bones of hearing for a year after an intact canal wall operation for cholesteatoma. The ear drum is opened at the second operation and the bones of hearing are then reconstructed. If a regrowth of cholesteatoma is found, the disease is again removed and reconstruction may be delayed for another 6 months or a year. Repeat CT scans may also be performed in some cases to avoid further surgery.
Even with careful microscopic surgical removal of cholesteatoma, 10% to 20% of cholesteatomas can recur. In children, some ear surgeons report up to 50% recurrence rates with the intact canal wall procedure. Thus, careful follow-up visits must be planned, in order to identify regrowth early on.
After the disease has been removed, a graft will be used to seal up any hole in the eardrum, and packing placed in the ear canal.
There are multiple variations of the mastoid operation, so your surgeon will explain the details which apply to you.


What happens after the operation?

You will stay in hospital at least one night after the operation. If the stitches are not dissolvable, they will be removed after one or two weeks, either by the hospital or your practice nurse. The packing will be removed from your ear after 1 to 3 weeks.
If you have a mastoid cavity after the operation, it will need regular care in the ear nose and throat outpatients department until it is entirely healed.


What are the risks of the operation?

The risks of a general anaesthetic.
The risks of the operation are similar to those of leaving the cholesteatoma in your ear, only more controlled and much rarer. There is a risk of reduced hearing after the operation but this is often able to be improved by an operation at a later date once the cholesteatoma has been controlled.
There is a rare risk to the facial nerve resulting in a permanent weakness of the side of the face, (facial paralysis).
Dizziness. Frequently a temporary occurrence. Rarely may be a permanent problem
Sometimes a second operation is planned about one year after the original operation to check for recurrence of the cholesteatoma. There is also a risk of taste disturbance on one side of your tongue.


When can I wash my hair/swim/fly?

If you are careful about keeping water away from your operated ear, you can wash your hair after a week.
You should be able to swim about four to six weeks after the operation, depending on how well the operation has healed, and so you should ask your surgeon at your postoperative outpatients appointment.

When can I fly?

You should be able to fly at any time after the operation unless you have also had an operation to improve your hearing at the same time as the mastoid operation - again, check with your surgeon


Mr MingYann Lim MRCS