In many cases, the provision of classic in-the-ear or behind-the-ear hearing aids is perfectly adequate to support the speech comprehension of hearing-impaired patients. To do this, the devices amplify the sound and deliver it in this lifted form to the wearer's ear canal. However, what happens if the middle ear does not (no longer) have the ability to transmit sound, the hearing impairment becomes increasingly severe or anatomical reasons prevent the fitting of a hearing aid?
Hearing aid implants can provide an alternative to removable hearing aids in these cases and improve their wearer's chance of participating in the audible world. The insertion of an implant requires surgery, so the decision to use a hearing aid implant should be carefully considered. It should also be noted that it is never possible to achieve the same quality of hearing as with natural hearing. Nevertheless, implants are sophisticated hearing solutions that have the potential to significantly enrich everyday life.
Hearing implant and hearing aid: differences at a glance
Hearing aid implant types
Which hearing aid implant is used depends on the form of hearing loss or hearing impairment. The common types of hearing aid implants form inner ear implants - also known as cochlear implants -, middle ear implants, bone-anchored hearing aids, and brainstem implants.
Accordingly, the application areas of the various implants include the following:
- Sensorineural hearing loss
- Combined hearing loss
- Conductive hearing loss
- Congenital and chronic hearing loss
- Misformed or absent auditory nerve
- Total hearing loss (but this is mostly difficult to treat if the hearing loss occurs before or during language acquisition)
The basic structure of a hearing aid implant results from two parts: The internal part, which is implanted and consequently sits under the skin, and the external part, which consists of an audio processor and is fixed externally to the scalp. Even fully implanted devices are not fully autonomous, they always need a connection to an external device for power.
Cochlear implants are probably the best-known hearing aid implants, but hardly anyone is sufficiently informed about them. The devices are sometimes used to treat congenital hearing defects, but are considered potentially helpful for all damage to the inner ear. The target population is primarily adults with bilateral deafness, individuals with progressive hearing loss (hypacusis), and children with severe hearing impairment - genetic or acquired.
Electronic impulses form the basis of the function of a cochlear implant: they generate sounds in the cochlea that ultimately enable understanding. This requires an external, behind-the-ear component that contains the speech processor. There is a wireless, inductive connection from the external to the internal component. The latter is located in the temporal bone and is in direct contact with the cochlea. Coded audio signals are sent via the transmitter coil of the outer component to the receiver coil of the inner component. From this, the auditory nerve is stimulated, resulting in stimulus transmission to the brain, through which a hearing impression is ultimately created.
Middle ear implant
In keeping with its name, the middle ear implant is inserted into the middle ear in a complex but low-risk operation. The procedure is considered for the treatment of perceptual or conductive hearing lossas well as a combination thereof. Middle ear implants are also an option when there is a block of the middle ear or outer ear, or when wearing an external hearing aid is anatomically impossible. In any case, the prerequisite for usability is intact inner hair cells.
For the function of the middle ear implant a magnet is needed, which realizes an anchoring of the external microphone with the inner speech processor. Here, the microphone acts as a kind of substitute to the auricle - it picks up the auditory information and sends it to the implant in the middle ear. Here, the signals are then transmitted via the ossicles to the inner ear, creating an auditory impression.
Bone anchored hearing aids/bone conduction hearing aids
Bone conduction hearing aids use the natural function of bones to conduct sound. This design is also referred to as Bone Anchored Hearing Aids (BAHA). Hearing implants are used for a variety of limitations, including chronic inflammation of the middle ear or ear canal, damage to the eardrum, conductive hearing loss,and malformations of the ear and ear canal.
The reason for its naming is that the implant - a titanium screw - is inserted into the bone. As a counterpart, a sound processor is attached to the implant externally behind the ear. To function, the sound processor first picks up sound from the environment, then delivers it to the screw, which uses vibration to transmit the audio signals to the inner ear. Consequently, no middle ear involvement is assumed, but an intact auditory nerve and a functioning inner ear are.
Brainstem Implant/Auditory Brainstem Implant (ABI)
Need for implantation of a brainstem implant arises when the auditory pathway has been damaged from birth or by traumatic as well as pathological events. Examples include neurofibromatosis type 2 and tumor diseases in which the tumor presses on the auditory nerve or damage was caused during tumor removal. Even in the case of a completely severed auditory nerve, the brainstem implant offers a way to partially restore hearing. The goal here is not so much optimal hearing, but rather a sense of hearing so that there is no exclusion from the auditory world.
During the very complex implantation, a small electrode is inserted directly into the brain stem, which is in communication with the external component via a small cable. Frequencies are transmitted to the electrode by the external sound processor, which causes stimulation of the auditory nerves by electrical impulses. Consequently, the stimuli are transmitted to the brain, where they are evaluated and the auditory impression is created. With the help of a brainstem implant, primarily the perception of ambient sounds is successful. Only with training in lip reading can speech comprehension result from the sounds.
Hearing aid implant cost
Any hearing aid implantation is a surgical procedure that should always be well thought out. What provides relief is the assumption of all costs for implant, aftercare and rehabilitation by the statutory health insurance. Because in terms of price, hearing aid implants - depending on the type of implant and the individual conditions of the patient, which influence the degree of difficulty of the procedure - range up to €40,000.
The most cost-effective are the bone conduction hearing aids, which range from €3,000 - €5,000. Middle ear implantsare in the price range of €10,000 to €30,000, depending on the treatment method. Brainstem implants are also available for a price of approximately €30,000. The cost of the cochlear implant is approximately €40,000. Please note that these are only approximate values. The final price will depend on the factors mentioned above.