About Middle Ear Implants

Middle Ear Implants

WHAT ARE MIDDLE EAR IMPLANTS?

The middle ear is the part of the ear which contains the hearing bones. The hearing bones connect the ear drum to the inner ear.

Sound makes the ear drum vibrate. This in turn causes the hearing bones to vibrate. Because the inner most hearing bone(the stapes) is attached to the inner ear when it vibrates it makes the fluid in the inner ear vibrate.

A middle ear implant is a vibrating device which is attached to the hearing bones or the inner ear and causes the hearing bones or the inner ear fluid to vibrate.

The vibrating part is implanted under the skin and contains a magnet. The magnet holds an external part in place on the side of the head.

The external part has a microphone which picks up sounds and send the information to the internal part making it vibrate at the correct frequencies. The vibrations pass into the inner ear and stimulate the hearing nerve allowing the patient to hear.

WHAT MIDDLE EAR IMPLANTS ARE AVAILABLE?

THE MEDEL VIBRANT SOUNDBRIDGE
THE COCHLEAR CARINA
THE ENVOY

WHO MIGHT BENEFIT FROM A MIDDLE EAR IMPLANT?

Three groups of people may benefit from a MIDDLE EAR IMLANT:

1. Patients with a sensorineural hearing loss who are unable to use a hearing aid.

2. Patients with a CONDUCTIVE hearing loss

3. Patients with a MIXED loss.

1. SENSORINEURAL HEARING LOSS.

For people with a nerve (sensorineural) hearing loss the treatment is usually with a hearing aid. However some people have significant problems with hearing aids and are unable to use them at all or with any consistency.

Problems with hearing aids:

Recurrent infections
Difficult to fit due to anatomical problems
Blockage with wax
Occlusion effect
Feedback

Mr Mike Pringle FRCS(ORL), Consultant Ear, Nose and Throat Surgeon, Portsmouth, UK

Diagram of the Vibrant Soundbridge in place. The little gold coloured ‘vibrator’ is attached to the middle hearing bone( the incus).

The Middle Ear Implant attaches directly to the normal hearing bones. It does what a hearing aid does which is to make the bones vibrate with more energy so that more energy goes into the inner ear to try and help overcome the hearing loss.

As with a hearing aid there is a limit to the amount of energy which can be put into the inner ear so there are people who’s hearing is so bad that the Middle Ear Implants will not be powerful enough.

2. A CONDUCTIVE HEARING LOSS

This is where sound can not get through to the inner ear. Possible causes are listed below. Often this sort of hearing loss can often be treated with a normal hearing aid but some people can not use a normal hearing aid either because it causes ear infections or because the patient may not have an ear or ear canal.

For people with a conductive hearing loss who suffer repeated infections when using a normal hearing aid a Middle Ear Implant can be very effective at not only helping the hearing but also allowing the ear to dry up and avoid infections because the ear canal is no longer blocked.

Causes of a conductive hearing loss where a Middle Ear Implant may help:

abnormal or absent pinna
blocked or absent ear canal
recurring ear canal infections
damaged or missing hearing bones
any cause of a conductive hearing loss where a normal hearing aid causes problems.

The Middle Ear Implant allows the sound vibrations to bypass any problems in the ear canal or hearing bones by attaching directly to what is left of the hearing bones or to the inner ear allowing sound to get into the healthy cochlea.

3. MIXED hearing loss: In some people with a conductive hearing loss the inner ear is also not working very well. For these people a certain degree of amplification is needed.

A Middle Ear Implant is able to provide amplification because it has the power to vibrate strongly and put that energy DIRECTLY into the inner ear (the cochlea).

MIDDLE EAR IMPLANT V BONE CONDUCTION DEVICE.

For people with a healthy inner ear a Bone Conduction Device will work as well as a Middle Ear Implant. The Middle Ear Implant comes into its own as the nerve hearing gets worse.

As I’ve said the function of the ear is to vibrate the fluid in the inner ear. A Bone Conduction Device does this by vibrating the whole skull. This will make the inner ear fluid vibrate but without much extra energy which is not a problem if the inner ear is normal.

When the inner ear is not normal and the patient has a sensorineural hearing loss more energy (bigger vibrations) needs to be put into the inner ear to stimulate the remaining nerve endings to allow the patient to hear.

The advantage of the Middle Ear Implant is that it is directly attached to the inner ear fluids via the hearing bones or the round window so it can put more energy into the inner ear and provide more amplification.

MIDDLE EAR IMPLANTS – WHAT IS AVAILABLE?

There are a number of Middle Ear Implants. The two ‘commoner’ ones are the Medel Vibrant Soundbridge and the Otologics Craina

THE MEDEL VIBRANT SOUNDBRIDGE

This is probably the most commonly implanted Middle Ear Implant worldwide. It has been around since the early 1990. The designer of the device was deaf and now has one in each ear! It is well established effective and safe. The Company who invented the device is now owned by MEDEL – one of the major Cochlear Implant companies. They continue to support and develop the device……

THE COCHLEAR CARINA

A company called Otologics produced the first TOTALLY implantable hearing aid where everything is under the skin. The microphone and battery which are normally on the outside are implanted under the skin with all the sound processing parts. The battery needs to be charged for about an hour every night with a mobile device which is held onto the side of the head with a magnet. They also make a semi-implantable model where the battery and microphone are on the outside. The Carina is probably slightly more powerful than the Soundbridge. Otologics have just been taken over by COCHLEAR one of the other major cochlear implant manufactures………..