Bone conduction implant systems

Bone conduction implants

A bone conduction implant works for conductive or mixed hearing loss, which occurs when sound cannot take its natural path through your outer and middle ear to your inner ear, perhaps due to a congenital problem or damage.

What’s the difference between active and passive bone conduction?

Bone conduction systems can be divided into two types: active systems, which directly stimulate the bone via a surgical implant within the temporal bone behind the ear, leaving the skin intact, and passive systems, which apply vibrations to the bone indirectly through external pressure on the skin. Bone conduction hearing aids and bone anchored hearing aids (BAHAs) are examples of passive systems.

How does an active bone conduction implant work?

A bone conduction implant bypasses your outer and middle ear, transmitting sound waves through the bone straight to the cochlea in your inner ear.

It consists of two main components: an externally worn audio processor and an implant, which is surgically positioned under the skin in the temporal bone behind your ear. The audio processor is held directly over the implant by magnetic attraction and can be comfortably worn under your hair. Here’s what happens:

Source: MED-EL

  1. The audio processor collects sound waves through integrated microphones.
  2. The audio processor converts the sound waves to electrical signals.
  3. The electrical signals are transmitted through your skin to the implant.
  4. The implant converts the signals into mechanical vibrations, which are transmitted to your skull.
  5. Your skull bone conducts the vibrations to your inner ear.
  6. Your inner ear processes the mechanical vibrations in a natural way, transmitting the acoustic information to your brain.

Can you get an active bone conduction implant on the NHS?

There’s no NICE guidance for active bone conduction implants, though it is possible to get them on the NHS if you’re found to be medically suitable. Your hearing score should be no lower than 45 dB in a bone conduction test and it should be established that you are unable to wear conventional hearing aids for medical reasons.

A full hearing and medical assessment will be made to determine whether you are suitable for surgery and likely to derive sufficient benefit from the implant.

Who is an active bone conduction implant suitable for?

  • People with mild to moderate conductive hearing loss, including those who are deaf in just one ear (single-sided deafness), and who can’t wear hearing aids for medical reasons such as discharging ears or the absence of ear canals. Because the skin heals after surgery and is therefore intact, it’s a good alternative for people who have problems with soft tissue healing, diabetes, skin or keloid scarring issues.
  • You must be five years of age or older and have a functioning auditory nerve and cochlea.

Two implants are recommended for:

  • Children who have a severe to  profound hearing loss and don’t get enough benefit from hearing aids after three  months.
  • Adults who have a severe to profound hearing  loss and don’t get enough benefit from hearing aids after three months and who  are also blind or have certain other disabilities.
cochlear implant pros and cons

Benefits of an active bone conduction implant system

  • Volume and quality of sound are better than with passive systems as vibrations are generated inside your skull and so don’t have to pass through the skin.
  • The audio processor, worn on the outside of your head, is much smaller, lighter and more discreet than the passive system’s sound processor.
  • The active system doesn’t require skin pressure for stimulation so is more comfortable and can be worn for as long as you like, though you should take it off before sleeping or bathing.
  • Compared with a BAHA, there is no titanium screw in the skin. With a BAHA, the pierced area requires daily cleaning and can cause skin irritations and infections in some people. There’s no risk of this with an active bone conduction implant because the skin is left intact.

Things to consider

Implant surgery is generally considered very safe but any type of surgery carries some degree of risk. This can range from risk due to anaesthetic and post-operative infection.

However, it’s a relatively quick and simple operation, taking from around 30 minutes to an hour, and can sometimes be done under a local anaesthetic. Ask your surgeon to explain how the risks and benefits apply to you.

Information about cochlear implant risks

What to look for in an active bone conduction implant system

  • MRI compatibility  –  It’s important to know whether your device is compatible with MRI scanners used for diagnostic medical tests, and to what degree
  • Adaptive directional microphones – These help identify and filter out background noise.
  • Feel and appearance – Audio processors vary in size, weight and some have interchangeable covers in different colours and designs, allowing you to make a bold statement or to wear it discreetly.
  • Volume and quality of sound are better than with passive systems as vibrations are generated inside your skull and so don’t have to pass through the skin.
  • The audio processor, worn on the outside of your head, is much smaller, lighter and more discreet than the passive system’s sound processor.

Connect with a HearPeers mentor

to find out more about life with a bone conduction implant.

Reference:

[1] Sprinzl GM, Wolf-Magele A: The Bonebridge Bone Conduction Hearing Implant: Indication criteria, surgery and a systematic review of the literature.Clin Otolaryngol, 2015 Jun; doi: 10.1111/coa.12484

Disclaimer

The contents of this website are for informational and educational purposes only and do not constitute medical advice. This website should not be used to diagnose or treat health conditions. You should contact a healthcare provider if you have healthcare related questions.