Otosclerosis is a genetic condition that affects the bone of the inner ear. This bone is the hardest and oldest bone in the body, but in Otosclerosis, spots of softening and new bone growth occur so that the stapes (Stirrup bone – the smallest one and which is connected to the inner ear) becomes fixed and unable to vibrate. This causes a conductive (middle ear) deafness, which is very treatable, either with surgery or by fitting a hearing aid. There is often a family history of the condition, it can be made worse by pregnancy (but men are equally affected) and it can also cause an inner ear deafness alone or a mixture of both. What is a Stapedectomy?
This is the operation where part of the stapes is removed, a new opening is made through its base (called the footplate), and a small piston used to reconnect the other bones of hearing in the middle ear to the inner ear. In other words, the fixed stapes is by-passed. A recent modification is called a stapedotomy, the difference being the smaller size of the opening made in the footplate (thought to be safer). How is the Operation Performed?
Under a general anaesthetic, It is usually done down the ear canal, with a small incision at the entrance to give better access. The ear-drum is lifted forwards, sometimes a little bone of the ear canal has to be drilled away and then the stapes is dealt with as above, if fixation is confirmed. The improvement in hearing is instant, the ear-drum is replaced and then held in place by various forms of packing for a week. This, of course, makes the ear feel blocked until the packing is removed in the clinic.
Generally you will stay overnight in hospital and for the next week it is important to avoid any lifting, straining or other vigorous activities. There may be significant unsteadiness and until that settles care with movement must be taken. Tinnitus may be worse but improves once the packing is removed. The final hearing result takes about a month to be apparent, but during that time you will notice greatly improved hearing. Some people find the world a very noisy place, and that sounds are a bit tinny or distorted and take a long time to adapt to their new hearing, especially if their deafness has been longstanding.
The main risk involves damage to the inner ear. This can be permanent damage and in a small percentage (1-2%) severe, with no useful hearing left. Less severe damage usually affects the higher frequencies but the risk is reduced by using non-drilling techniques like KTP laser around the stapes.
Sometimes (2-3%) the piston does not sit well so that the hearing result is not as good as it should be. This situation can be corrected by a revision procedure, done the same way as the original.
The sensation of taste to that side of the tongue can be affected, but it usually settles after 1-2 months.
The facial nerve runs very close to the stapes and although it would be very rare for it to be damaged, sometimes it prevents access to the footplate so that the piston can’t be put in.
Tinnitus is variably changed by stapedectomy – it may be improved but occasionally gets worse.
The decision to have a hearing aid, surgery, a mixture of both or do nothing is best made by an informed discussion between you and your surgeon. You should make sure he/she is experienced in the techniques of stapedectomy.