Assessment for percutaneous and magnetic bone conduction hearing devices (BCHD) and middle ear implants (MEI)

Hearing implant assessment information

Who is the leaflet for? What is its aim?

This leaflet is for anyone referred for a BCHD or MEI assessment. The Emmeline Centre is a specialist hearing implant centre for the East of England. We provide services for people of all ages with hearing problems. We offer a range of hearing implants including cochlear implants, bone conduction hearing devices (sometimes also called BAHAs) and middle ear implants.

What is a hearing implant?

A hearing implant is used when people are not able to wear, or do not get adequate benefit from, a conventional hearing aid. Hearing implants have an internal part (implant) and an external part worn on the head (processor). The processor picks up sound and sends it to the implant which stimulates the skull or tiny bones in the middle part of your ear to enable you to hear.

Depending on the type and level of hearing loss, a hearing implant may help by:

• Passing sound directly to the inner ear via vibrations of the skull.
• Providing additional energy to the hearing pathway via the middle ear.
• Delivering sound over the skull directly to the other ear.

The assessment process

The aim of the implant assessment is to provide you with more information about implant options and to see if a hearing implant will be more suitable than a conventional hearing aid. The audiologist will test your hearing and discuss the different types of hearing implant with you.

We will consider all types of hearing implants during your assessment. Not everyone is suitable for a hearing implant and there are several factors that influence which implant is recommended.

You will have the opportunity to discuss the team’s recommendation with the surgeon.

Typically, Adult BCHD or MEI assessment will take two visits, and children may trial the temporary device for longer.

• During the first visit you meet an audiologist and sometimes a nurse to clear your ears. At this visit, your hearing and hearing aids will be checked. If suitable you may be given a hearing implant processor on a temporary headband to trial for at least 2 weeks and often longer.
• Some patients need a head scan (CT scan) before a decision can be made about the most appropriate hearing implant, but it may take many weeks for this to be completed. Children may need scans under sedation or anaesthetic. Please refer to Assessments under anaesthetic for your child | CUH
• At the second visit you will see an audiologist again to complete testing and review how you found the headband trial. If you are suitable for a hearing implant and wish to proceed, you will have an appointment with the nurse for a medical assessment. We will schedule further appointments to meet the surgeon, for the surgery and fitting of the hearing implant.
• Some patients may be suitable for a hearing implant but choose to not go ahead with surgery. You may prefer to continue using your hearing aids or continue using a hearing implant processor on a headband.
• If a hearing implant is not suitable we will give you advice on how to best manage your hearing difficulties and refer you back to your local hearing aid service. If your hearing or ear health changes you can ask your GP/local audiologist for a re-referral to us.

The operation

• Surgery lasts between thirty minutes and three hours for each ear dependant on the device you are having fitted.
• In some cases the implant procedure may need to be carried out in two stages and require two operations.
• For adults the operation is usually performed under general anaesthetic for magnetic implants and local anaesthetic for a percutaneous BCHD. Children will be offered a general anaesthetic.
• A small area of hair may be shaved.
• The wound is closed using stitches and/or glue which should dissolve within a few weeks.
• A head bandage will be in place after the operation. This will be removed either before you go home or the following morning. Other dressings and healing caps should be left until they are removed at your post-op check with the nurse.
• You will normally be discharged from the ward on the same day, which may be in the late evening. You will need to have someone else drive you home.
• Same sex bays and bathrooms are offered in all wards except critical care and theatre recovery areas where the use of high-tech equipment and/or specialist, one to one, care is required.

After the operation

• You may experience some discomfort and swelling for up to 48 hours after the operation. Have paracetamol or ibuprofen ready for this time.
• You should avoid getting the wound wet for at least one week or until the nurse says you can get your head wet again. Meanwhile, use a dry shampoo, don’t swim.

First appointment:

• You will have a post-op check with the nurse one to two weeks after the operation to check the wound is healing.
• If you have been fitted with a BCHD and have been trialling a temporary test band, do not fit your sound processor to your abutment or implant before your first programming appointment (switch on). Fitting the processor early could potentially damage the fixture and result in it falling out.

Second appointment:

• You will have a programming appointment where the audiologist will check your implant, programme the sound processor and show you how to use it. If you have been using a sound processor on a temporary test band you must bring this to your appointment.

Third appointment:

• You will have a review appointment for the audiologist to check the settings of your processor to ensure you are getting the best sound.

Routine review:

• You will have an appointment after a year to review your hearing and hearing implant settings. After that, we expect to review adults every 5-6 years for an external processor upgrade, but please let us know if you have problems in between appointments. Children will be reviewed alternately by audiology and rehabilitation clinicians.

Expected benefits and risks

The risks and benefits from a hearing implant depend on many different factors and must be reviewed on an individual patient basis. Your audiologist and the ear, nose and throat (ENT) consultant will discuss this with you. If you have any questions please ask your audiologist or the ENT consultant.

Compared to conventional hearing aids a hearing implant may:

• Give consistent and appropriate amplification for your hearing loss.
• Stop any discomfort and irritation associated with wearing conventional hearing aids.
• Reduce problems with chronic ear infections or allergies as a hearing implant leaves the ear canal open.
• Give a more natural clear sound, with less distortion, but this may feel slightly quieter
• Cause less feedback (whistling/squeaking from the conventional device/hearing aid).
• For those with single sided deafness (severe or profound hearing loss in one ear, with much better hearing in the other ear) a hearing implant sends the sound via bone conduction from the deaf side to the functioning inner ear on the hearing side.

There are some risks associated with all types of hearing implant, including:

• Skin inflammation/swelling.
• Infection of the wound.
• Minimal permanent hair loss along the surgery site.
• Numbness around the surgery site for several months which generally improves with time.
• Loss of cerebrospinal fluid, which cushions the skull, if the bone is too thin - this is very rare.

BCHD specific risks

• Infection around the abutment (percutaneous BCHD).
• Skin overgrowth and need for skin reduction surgery (percutaneous BCHD).
• Implant loss due to failure of implant to bond with skull bone, normally through infection or trauma (magnetic and percutaneous BCHD).

MEI specific risks

• Implant loss due to failure of implant, normally through infection or trauma.
• Facial weakness.
• Altered taste.
• Risk of slight deterioration of unaided hearing due to additional implant weight in middle ear.
• 1% risk of complete hearing loss.

Other things to consider

MRI scans

MRI scans are a common medical procedure. With all hearing implants you must take off the sound processor before having an MRI scan. It is important to tell the radiographer that you have a hearing implant and to take your sound processor off before entering the examination room. After the implant operation you will receive an ID card which has information about MRI scans, and you should show this to the radiographer. You can also purchase medic alert bracelets. Always contact the Emmeline Centre to let us know before having an MRI scan.

A percutaneous BCHD fixture is made of titanium and will not be affected by the magnetic field. However, some manufacturers specify a maximum scan time as the abutment may get slightly warmer. As there are potentially magnetic parts in the sound processor, you must take off the sound processor for an MRI scan. Further safety guidelines for other medical procedures are available from the manufacturer.

Most BCHD and MEI implants are MRI safe for a certain strength (1.5 Tesla) scan. These devices include the Cochlear BAHA Attract, Cochlear Osia, Oticon Sentio,Med-El BoneBridge (601 & 602) and Med-El SoundBridge VORP 503). Additional head bandages may be required depending on the device. There will be a shadow on the image/scan around where the implant is. For higher power MRI machines it may not be possible to perform the scan with your implant/magnet in place. You must take off the sound processor for an MRI scan. Further safety guidelines for other medical procedures are available from the manufacturer.

Patients implanted with a Cochlear Carina implant or Med-El SoundBridge VORP 502 should not have an MRI, and should not enter an MRI Suite or come into close proximity to other sources of strong magnetic fields.

Wireless accessories

There are a number of wireless accessories that can be used with the different sound processors. Some accessories are available on the NHS, others you may choose to purchase. Your audiologist will work with you to identify which device offers the most suitable accessories for your hearing and lifestyle needs.

Waterproofing

Sound processors are not fully waterproof, so need to be removed before swimming, bathing etc. In rainy conditions use an umbrella or hood to keep your processor dry. Once you have removed your sound processor you can go swimming, bathing etc, without any additional precautions.

Cochlear Osia, Med-El BoneBridge and SoundBridge can be used with a fully waterproof cover called WaterWear/Aqua which would allow you to continue to access sound while swimming, in the bath etc. Replacements of these covers are not supported by the NHS.

Alternatives

If you are not suitable for a hearing implant or choose not to proceed with one there may be a number of alternatives.

• Long term band user - Some patients continue to use a sound processor on a band, soft head band, sound arc or sticky pad. We may recommend this to some patients such as young children, while we wait for their skull to grow.
• Hearing aids and CROS devices - As part of your assessment we will review your hearing aids and coupling method i.e. ear moulds vs. slim tubes. If appropriate we may reprogramme the hearing aid, change parts of it or replace it altogether.
• Assistive listening devices - Assistive listening devices are designed to help people with hearing loss hear better in noisy environments, where there is a significant distance between them and the sound they wish to hear, or when they are interacting with another piece of technology such as a phone.
• Strict ear and mould hygiene - Some patients are referred for a hearing implant because of problems with persistent ear infections. In some cases this can be effectively managed with regular aural care (specialist ear cleaning), special ear moulds and a strict routine of cleaning the ear mould