BAHA and cochlear implants

Do you know much about hearing implants?

You’ve likely heard of hearing aids, but do you know much about hearing implants? These impressive devices help those living with profound hearing loss and other conditions to enjoy the sensation of sound again or, in some cases, for the very first time.

Hearing implants

For some people living with profound hearing loss, standard hearing aids simply aren’t compatible with their diagnosis. While standard hearing aids help to amplify sound, they don’t necessarily assist people with conductive hearing loss, damage to the cochlea and other conditions. Hearing implants, such as cochlear implants and bone anchored hearing aids, provide an alternative solution.

Auditory brainstem implants

For some, a cochlear implant or a bone anchored hearing aid isn’t an option. If a person has a cochlea that is very abnormal or has issues with the nerves that transmit electrical impulses from the ear to the brain, the aforementioned devices won’t necessarily work. Auditory brainstem implants, however, may be an option. 

Auditory brainstem implants are surgically implanted and are designed to help improve sound awareness. The medical device bypasses the inner ear and auditory nerve, stimulating the hearing pathways of the brainstem directly. They collect sound using a small microphone, converting the sound waves collected into electrical impulses through a processor. The impulses are transmitted to a receiver which sends the signals directly to the brainstem through an implant array. Much like with cochlear implants, auditory brainstem implants do not restore hearing fully.

BAHA: the Bone Anchored Hearing Aid

Bone anchored hearing aids (BAHAs) are a type of hearing aid that is surgically implanted behind the ear. The implanted device takes advantage of the skull’s natural bone conduction to bypass the outer and middle ear, delivering sound signals directly to the inner ear.

Several conditions may benefit from the use of BAHAs, including conductive hearing loss, mixed hearing loss, single-sided deafness and any ear conditions that may prevent the use of a standard hearing aid.

How does a BAHA work?

Bone anchored hearing aids are composed of two main components: an external sound processor and a titanium fixture. The titanium fixture is surgically implanted behind the ear, creating an anchor point for the processor. 

Once installed, the processor uses a small microphone to pick up sounds from around the user, converting them into vibrations. The vibrations travel into the implant and then out through the bone that surrounds it, making use of the skull’s natural conductivity. The vibrations soon reach the inner ear and the cochlea, where the tiny hair cells within the cochlea are stimulated. The electrical impulses created by the hair cells are then sent along the auditory nerve for processing by the brain.

Benefits of bone anchored hearing aids

Depending on the type of hearing loss experienced, standard hearing aids may not necessarily work for everyone. For those who have conductive hearing loss, mixed hearing loss or other conditions that affect the outer or middle ear, BAHAs may be an option to consider. Without the dependency on the outer ear, the eardrum or the middle ear, the hearing implants help to deliver sound vibrations direct to the cochlea.

BAHAs may be an option for those who cannot wear a standard hearing aid. From congenital conditions that have prevented the outer ear or ear canal from developing normally, to chronic otitis media and other diseases that affect the canal, there are many reasons why someone may not be able to use a standard hearing aid. Without reliance on the outer ear or ear canal for support, BAHAs may be an option when standard hearing aids aren’t.

As BAHAs do not require the use of a traditional ear mould, many people living with the hearing implants find them comfortable and quite easy to wear. It is worth noting, however, that extra care does need to be taken if participating in sports and some other activities.

The cochlear implant

A cochlear implant is a small, surgically implanted electronic device that may help to partially restore the hearing of those living with severe or profound hearing loss. Unlike standard hearing aids, which amplify sounds, they help to deliver sound signals directly to the auditory nerve. This allows the signals to bypass parts of the inner ear that may have been damaged or may not have developed properly.

While cochlear implants do not restore hearing completely, they can provide those living with hearing loss with a better perception of the sounds around them. Some rehabilitation will be required after surgery to help patients recognise and understand sounds that may sound different once the implant is in place.

How does a cochlear implant work?

Cochlear implants are composed of two main parts: an external component, including a microphone, processor and transmitter, and an internal component, featuring a receiver and an electrode array.

The microphone collects sound waves from around the user, including speech and other sounds, and sends them to the processor. The processor converts the sound waves into digital signals which are then sent from the transmitter to the receiver. The receiver converts the digital signals into electrical impulses that make their way through to the electrode array, positioned within the cochlea. The electrode array stimulates the auditory nerve, sending the impulses to the brain for processing.

Cochlear implants for children

In some circumstances, cochlear implants may be considered for children with severe to profound hearing loss who have not benefited from standard hearing aids. As with cochlear implants for adults, child cochlear implants are fitted during surgery, so all risks must be assessed, especially if the child has any additional medical conditions.

It’s recommended that implantation should occur as early as possible to ensure that the child has the greatest exposure to sound as their speech starts to develop. Regardless of the age of the child, speech and language therapy will be required to help them get the most from their cochlear implant.

Cochlear implant cost

The cost of a cochlear implant does vary, although in New Zealand they typically cost anywhere between $18,500 and $50,000 per implant. Most patients who are considered to be good candidates for a cochlear implant will require at least one implant, with costs increasing where two are required.

In New Zealand, funding is available from the Ministry of Health for patients who meet the Ministry’s eligibility criteria. View the Ministry of Health’s cochlear implant page to find the latest information about the scheme and the current eligibility criteria.

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