Vincent Cumberworth BSc FRCS Consultant Ear, Nose and Throat Surgeon

Clementine Churchill Hospital Sudbury Hill Harrow Middlesex HA1 3RX
Private Secretary: Tel: 020 8872 3866 Fax: 0208872 3861

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Otosclerosis

During the process of hearing, sound is initially collected by the eardrum and then is transmitted across the middle ear by 3 small ossicles (bones). The first ossicle is the malleus, the second the incus and the third the stapes. Rarely in humans it is possible for this third bone to become fixed. It moves in the form of a “rocking piston” with its footplate or base residing in an area called the oval window, through which energy transmission passes from this mechanical lever system to agitate the endolymph fluid in the cochlea, in the inner ear. Here the sound energy is converted into movement of hair cells producing electrical impulses which are transmitted along the fibres of the auditory nerve, the to the brain. If the base of the footplate becomes fixed, then sound is not properly transferred through to the fluid filled space of the inner ear and this produces a conductive hearing loss. This is typically of 40 to 60 decibels (dB). Often this is described as a percentage loss, although the scale of hearing loss is actually logarithmetic.

Management:

Observation: It is possible that no further intervention will be required and your ENT Specialist may elect to keep this under close observation for a period of time.

Hearing Aid: This problem produces a conductive hearing loss, which is relatively flat across the frequencies and often a hearing aid can be particularly beneficial. I personally recommend trial of a hearing aid for all patients before any consideration of surgery.

Surgery: Stapedectomy is the name of the procedure which is performed if surgery is decided upon to attempt to improve the condition. This is a procedure to remove the stapes and make a very small hole in the footplate and reconstruct the ossicular chain by inserting a small Teflon piston. Sometimes a small vein graft may be placed over the oval window.

The overall results of the operation are very good; around 90% of patients would expect to get a significant improvement in their hearing afterwards. The operation is performed in the UK typically under general anaesthesia and 1 – 2 weeks off work would be advised afterwards, probably with a hospital stay of 2 days after the surgery.

The principle complication however is of a dead ear and this can occur in up to 3% of cases. In this unfortunate instance the whole of the hearing on the operated side is lost and this then is not even amenable to improvement by a hearing aid. Typically, if there is bilateral, both sides, disease then the worst hearing ear would be operated on first. Also, should there be bilateral disease, then typically at least one and possibly 3 years may be advised before operating on the second side in case there is any later loss of hearing, depending on the individual preference of the surgeon.

It is possible to have a slight change in taste just on the lateral (side) border of the tongue. Sometimes there is a slight metallic taste there following bruising or division of the chorda tympani nerve, which supplies this area. It crosses the middle ear, almost directly across the area of surgery in some cases. This may well be a temporary problem but just occasionally can be permanent.

There are small risks of producing dizziness or imbalance post-operatively, which usually settles, and occasionally there may be tinnitus. Generally this also would settle but the outcome of accompanying tinnitus in otosclerosis may be slightly unpredictable and should be discussed individually with the surgeon.

It is advisable to avoid vigorous nose blowing and air travel for the first few weeks after surgery. Hearing improvement may not be noticeably dramatic immediately on recovery, as often there is some dissolving dressing around the piston or some accumulation of small amounts of blood clot or fluid in the ear after the procedure, which then settles.



© Vincent Cumberworth 2005