Otosclerosis

Otosclerosis is abnormal bone growth in the middle and inner ear that locks one of the tiny hearing bones in place so it can no longer pass sound on. Hearing fades slowly, over years, and most people do not notice the change itself — they notice that they keep asking others to repeat things and that the television has crept louder. Total deafness is rare: hearing aids or surgery almost always bring speech back within reach.

How otosclerosis shows itself

Hearing usually drops in one ear first, with the other ear following some years later. The ear does not hurt, nothing runs from it and it looks entirely healthy from outside, which is why many people come to a doctor years after the first changes.

The usual complaints are:

• speech is audible but not clear, especially higher women's and children's voices;
• the volume goes up and you ask people to repeat themselves when several are talking at once;
• ringing, buzzing or hissing in the ear — tinnitus goes with otosclerosis in most people;
• your own voice sounds too loud, so without meaning to you start speaking quietly;
• in a noisy place, on public transport or in the street, you follow the other person surprisingly better than in a quiet room;
• less often, dizziness and feeling unsteady on your feet.

The first signs usually appear between the ages of about twenty and forty-five, well before age-related hearing loss. Otosclerosis is roughly twice as common in women, and the change is often first noticed during pregnancy or shortly after childbirth.

What happens to the bone in the middle ear

Sound travels down the ear canal, moves the eardrum and passes on to the inner ear through a chain of three tiny bones — the hammer, the anvil and the stirrup. The base of the stirrup sits in the oval window of the cochlea like a piston and has to move freely.

In otosclerosis the dense bone around that window is remodelled: it first turns spongy and then hardens and welds the base of the stirrup in place. The piston jams, and part of the sound simply never reaches the cochlea. If the remodelling spreads into the wall of the cochlea itself, the hearing nerve is affected too, and surgery alone will not settle the problem.

Why the process starts is not known. About half of those affected have a close relative with otosclerosis: the tendency runs in families, but not everyone who inherits it develops the condition. Female sex hormones clearly play a part as well, which is why the condition is commoner in women and why pregnancy often speeds the hearing loss up.

What otosclerosis is mistaken for

Painless hearing loss is a non-specific complaint. Before settling on otosclerosis, a doctor rules out commoner and more urgent causes:

• earwax plug — the ear blocks quickly, often after a shower or after poking a cotton bud in, and hearing returns as soon as the wax is removed;
• fluid in the middle ear after a cold or an ear infection — a sloshing, blocked feeling and hearing that changes from day to day;
• a hole in the eardrum or the aftermath of chronic ear infections — there was discharge in the past and hearing dropped in a step;
• cholesteatoma — long-standing, foul-smelling discharge; it erodes bone and needs surgery, so it should not be left;
• age-related hearing loss — both ears together, high tones worst, usually starting after sixty;
• noise-induced hearing loss — power tools, shooting, loud music through headphones;
• Ménière's disease — attacks of severe vertigo lasting hours, fullness in the ear, and hearing that comes and goes;
• a tumour of the hearing nerve — loss and tinnitus on one side only, sometimes with numbness of half the face and unsteadiness; it is uncommon but must not be missed, and it is found on an MRI scan, not on a hearing test.

When to see a doctor straight away

Otosclerosis develops over years, so any rapid change in hearing is not otosclerosis and needs attention at once. Do not wait for a routine appointment if:

• hearing has gone or dropped sharply over hours or a day, usually in one ear — sudden hearing loss is treated in the first few days, after which the chance of recovery falls away quickly;
• the loss began after a head injury, a dive, a blast or a very loud noise;
• sudden vertigo with nausea and vomiting comes together with worsening hearing;
• you develop ear pain, discharge or a fever;
• the noise in the ear throbs in time with your heartbeat, or you hear your own footsteps and voice as though inside a barrel;
• along with the hearing loss, half of your face goes numb or weak, you see double, or you are unsteady walking.

Call an ambulance — in Spain, Italy, Portugal, Poland and Ukraine the single European number is 112 — if the skin behind the ear becomes red, swollen and tender, the ear starts to stick out, and along with this there is a high temperature, a severe headache, a stiff neck or confusion. That is how complications of an ear infection announce themselves, and there it is a matter of hours.

How the diagnosis is confirmed

In otosclerosis the examination of the ear is nearly always normal: the eardrum is intact and looks quiet. It is exactly that mismatch — a healthy-looking ear and poor hearing — that points to the diagnosis. A look through the otoscope is therefore not enough; measurements are needed.

• Pure tone audiometry. The main test. It shows the gap between what the ear picks up through the air and what it picks up through bone: with the stirrup jammed, sound carried through bone gets through noticeably better. Many charts also show a characteristic dip in the middle frequencies.
• Tympanometry and testing the stapedial reflex. The muscle reflex that normally fires in response to a loud sound disappears once the stirrup is fixed. It is one of the most telling findings.
• Speech audiometry. This measures not loudness but how many words you actually make out — which is what brought you in.
• Tuning fork tests. A quick check in the consulting room; it helps separate a middle ear problem from a nerve problem.
• CT scan of the temporal bones. Shows the patches of remodelled bone and the state of the cochlea; it is needed before surgery.
• MRI scan. Done when the loss is one-sided and a tumour of the hearing nerve is suspected.

Hearing aids

Hearing aids work well in otosclerosis: the obstacle is mechanical and the nerve is usually intact, so amplified sound arrives and is recognised. An aid does not stop the bone growing and does not cure the condition, but it gives back conversation, the telephone and the television.

An aid is chosen from your hearing test and normally fine-tuned once or twice over the first few months. Getting used to it takes some weeks: at first your own voice and the clatter of crockery seem far too loud, and that settles. If both ears have gone down, two aids are usually fitted, because that makes it much easier to tell where a sound is coming from.

Aids become the main choice when surgery is not suitable: when the other ear hears nothing, during pregnancy, alongside serious other illnesses, or simply when someone does not want an operation. There are also bone conduction devices, which carry sound through the skull and bypass the middle ear altogether.

Surgery on the stirrup

The surgeon removes the fixed part of the stirrup and puts a tiny prosthesis in its place, which passes the vibrations on to the cochlea again. The operation is done through the ear canal, with no outside cuts, under local or general anaesthetic, and takes about an hour.

The result is good for most people: the gap on the hearing chart closes, speech becomes clear again, and in some people the tinnitus quietens too. One ear is operated on at a time, starting with the worse one; the second follows no sooner than several months later.

Things worth knowing beforehand:

• in a small proportion of people hearing in the operated ear becomes worse rather than better, and that loss can be permanent — which is why an only hearing ear is not usually operated on;
• dizziness and nausea are possible in the first few days;
• taste on one side of the tongue sometimes changes, because a taste nerve runs right next to the stirrup; it usually recovers over weeks or months;
• tinnitus may remain;
• afterwards you will need to avoid blowing your nose hard, diving, lifting weights and flying for a while — your surgeon will give the timings.

There is no medicine that stops the bone growth. Fluoride preparations and osteoporosis drugs have been studied and have not shown convincing benefit in otosclerosis. If the process is far advanced and has involved the cochlea, a cochlear implant is discussed.

Living with reduced hearing and tinnitus

Tinnitus is loudest in silence, so a soft background at night helps: a fan, the radio, quiet music. Too little sleep, strong coffee and anxiety all make it worse. If the noise stops you sleeping or concentrating, retraining approaches and cognitive behavioural therapy help; it often fades on its own once someone starts wearing a hearing aid.

Conversation is easier with simple measures: sit facing the other person with the light on their face, turn the television off while you talk, and ask people to speak not louder but slower and more clearly. Protect your ears from loud noise — otosclerosis does not make you immune to noise damage.

If you have otosclerosis, close relatives whose hearing is poor should have it tested rather than leave it for years. And if you are planning a pregnancy, tell your ear specialist: hearing can slip faster during that time and follow-up is better arranged in advance.

Online consultation

An online appointment is a good way to sort out what your symptoms fit. The doctor will ask how and when the hearing dropped, whether there is tinnitus or dizziness, whether you have had ear infections or injuries, whether you have worked in noise, and whether parents or siblings hear poorly. Those answers already show whether the situation is urgent and where the tests should start.

In such a consultation you can go through a hearing chart and an ear specialist's report you already have, understand what the gap between bone and air conduction means, weigh up an aid against surgery, prepare for the conversation with a surgeon, or talk through recovery after an operation you have already had.

What cannot be done online is examining the ear, measuring hearing and recording a tympanogram: those need a face-to-face appointment and equipment. And if your hearing has dropped suddenly, do not spend time writing messages — that is the case where you need to be seen the same day.

This material is for information only and does not replace medical advice.