What is a cochlear implant?
A cochlear implant is an electronic inner ear prosthesis. It consists of an implant that is placed in the inner ear and a speech processor that is worn behind the ear like a hearing aid. The cochlear implant can help some people who have serious hearing loss within the inner ear.
The normal hearing process
The healthy ear captures sound waves and transmits them through the ear canal to the eardrum, causing it to vibrate mechanically. The three ossicles in the middle ear – malleus, incus and stapes – transmit the vibrations to the so-called oval window.
Immediately behind this is the inner ear with the fluid-filled cochlea (Latin for “snail”): This spirally wound bone cavity contains the actual auditory organ – a likewise wound, fluid-filled tube system of fine membranes.
Embedded in these membranes are sensory cells equipped with fine hairs that protrude into the fluid. If these vibrate due to the sound waves transmitted through the oval window, they transmit the stimulus to the brain via the auditory nerve. Here the signals are converted into acoustic information.
How does a CI work?
The receiver of the implant in the inner ear decodes the signals and transmits them via an electrode to the cochlea. There, the electrical impulses stimulate the auditory nerve. It passes the signals on to the brain, which processes the information as if it were a natural acoustic event. Hearing thus becomes possible with a CI.
Hearing aid & cochlear implant: the differences
What is the difference between a CI and a hearing aid? A hearing aid supports hearing that is still functioning. It contains a microphone that picks up sounds or noises in the environment. These are then converted into electrical signals, the volume of which is adjusted upwards by the built-in amplifier. Depending on the hearing impairment present, the hearing aid amplifies those frequencies or sounds that the affected person no longer perceives well.
If the transmission of sound is too severely restricted by the hearing impairment or if the conversion of sound waves into stimuli in the inner ear no longer works, the hearing aid reaches its limits. In such cases, a cochlear implant may be able to help. It takes over the functions of the inner ear and sends signals directly to the auditory nerve. The CI thus enables people without functioning hearing to hear – for example, children who were born deaf.
Cochlear implant: When is it used?
An intact auditory nerve and central auditory pathway are the basic requirements for a cochlear implant. Adults and children who are deaf or profoundly hard of hearing and for whom a conventional hearing aid, bone conduction hearing aid or implantable hearing aid does not enable spoken communication may benefit from a CI. The reason for the hearing loss or hearing loss – whether it is a hearing loss, noise trauma, medication or an accident – does not matter.
Specifically, cochlear implants are used for:
- Damage to the hair cells in the cochlea (known as cochlear deafness).
- Postlingual deafness (onset of deafness only after learning the language)
- Prelingual or inherited deafness in children (onset of deafness before learning the language)
- Hearing loss where speech understanding is not possible even with a hearing aid
Unlike children, adults who are already born deaf are not usually implanted with a cochlear implant. Their brain has never learned to recognize and interpret acoustic stimuli. Since it is already mature, it is not expected that it can still wrap up the appropriate skills for spoken language understanding. Therefore, a cochlear implant usually remains ineffective.
Unilateral or bilateral?
In principle, a cochlear implant can be used unilaterally or bilaterally – depending on the hearing impairment and how pronounced it is on each side.
Thus, for some patients, the optimal therapy may be to use a CI on one side and a hearing aid on the other. In other cases, a bilateral fitting with a cochlear implant makes more sense – speech understanding in noise and directional hearing are then generally better than with a unilateral CI.
The doctor discusses which measures will lead to the best hearing experience individually with each patient or with the parents of the child being treated.
Cochlear implant: advantages and disadvantages
Cochlear implants do not replace ears, but they do open up many possibilities for those affected. Interested persons should inform themselves in advance about these advantages, but also about the possible disadvantages and risks.
Advantages of the cochlear implant
Cochlear implants increase the perceptible range of sound and volume, so that the wearer can communicate more easily with his fellow human beings and thus (again) have a greater share in social encounters. Music can also be perceived better. In children, the earliest possible fitting of cochlear implants can promote speech development.
Disadvantages of the cochlear implant
Disadvantages and limitations associated with a cochlear implant:
- The implant must be taken off when sleeping as well as during certain sports such as swimming or martial arts.
- Strong magnetic fields, electrostatics, and high frequency signals can cause unintended irritation to the auditory nerve in rare cases.
- External, additional microphones may be needed to hear TV and audio as realistically as possible.
- Because a cochlear implant is a complex device, technical complications can occur.
- Care and maintenance both at home and in the care clinic can take a lot of time.
- Despite intensive training, full recovery of speech understanding rarely occurs because the linguistic information for the brain remains incomplete.
- Some people find a cochlear implant visually unappealing.
Cochlear implant in children
The procedure is possible from the sixth month of life – in individual cases, the cochlear implant can even be inserted in babies under six months of age. For children who only become profoundly deaf or hard of hearing over time, the procedure should take place as early as possible.
When is a CI not suitable for children?
The cochlear implant is not suitable in children in these cases:
- congenital absence of the cochlea
- Auditory nerve deafness
- lack of rehabilitation skills
Cochlear implant: the operation
Prior to cochlear implant surgery, there is extensive preparation. This includes:
- a general preoperative diagnosis
- examination of hearing and speech status
- imaging examination of the internal head structures by means of magnetic resonance imaging (MRI) or computer tomography (CT)
- a detailed personal consultation and explanation of the patient by the attending physician about the procedure, chances and risks of the intervention
There are cochlear implants of different models and from different manufacturers. The doctor and the patient (or the parents of the child to be operated on) decide together which device will be implanted.
How is a cochlear implant inserted?
From there, the surgeon drills a canal into the middle ear, from which he creates an opening into the inner ear through another hole. Through this access, he pushes the electrode into the cochlea. He anchors the actual implant in a separate bone bed behind the ear. During the operation, the cochlear implant is tested and the function of the auditory nerve is checked.
Normally, the patient can leave the hospital immediately afterwards. Postoperative checks include computed tomography (CT) or magnetic resonance imaging (MRI) to check the position of the implant in the ear, and careful supervision of wound healing. In this way, any complications can be detected at an early stage.
The final step is the individual adjustment of the speech processor after complete wound healing.
Cochlear implant: risks of the procedure
In addition to the general risks associated with any surgery (e.g., wound healing problems), specific complications sometimes occur during cochlear implant surgery. These include:
- Dizziness
- Damage to nerves in the surgical area
- Undesirable stimulation of other nerves (especially facial and gustatory nerves)
- Infections of the middle ear
- Tinnitus (ringing in the ears)
- formation of a fistula
- Bruising (hematoma)
- Loss of any residual hearing
- Material incompatibility
- Rejection of the implant
Rarely, a defective cochlear implant causes headaches. A new ear implant can help.
After insertion of the cochlear implant, problems with hearing may occur – especially in adults. This is because hearing with the electronic prosthesis is foreign at the beginning, and the wearer must first get used to it. Children have fewer problems here. They grow up with the implant in their ears, so the difficult adjustment is not necessary.
Cochlear implant surgery: What you need to keep in mind afterwards
Both basic postoperative therapy and follow-up therapy, as well as lifelong aftercare, are critical to the success of the procedure.
For children, parents, pediatricians and speech therapists are involved in the cochlear implant setting and follow-up care.
Basic therapy
In addition to general medical follow-up, basic therapy includes initial adjustment and gradual optimization of the speech processor:
After surgery, the cochlear implant is activated and adjusted for the first time. Special emphasis is placed on hearing and speech tests, checks, and intensive auditory-speech training. In addition, the patient is trained in the handling and use of additional devices.
Follow-up therapy
The basic therapy is continued in the follow-up therapy. The brain must become accustomed to the new artificial stimulation and learn the necessary perceptual and processing procedures. An intensive combination of training and recurrent adjustments of the speech processor form the basis for the success of the treatment. Regular audiometric checks help in this process.
Aftercare
A cochlear implant requires lifelong follow-up care by a clinic with appropriate experience. This aftercare serves as a medical and technical control and consultation. Doctors regularly check the patient’s hearing, speech and language performance and document it. The aim is to optimize and stabilize the patient’s individual ability to communicate.
Cochlear implant: Costs
Germany
The cost of a cochlear implant – i.e., the device, surgery and follow-up care – is around 40,000 euros. If the affected person meets the requirements for the procedure, the statutory health insurance companies cover the costs.
In the case of private health insurance companies, you should find out in advance whether the costs will be covered.
Austria
The costs for surgery and initial equipment are usually covered by a fund. Affected persons themselves then only have to pay for subsequent costs, i.e. for:
