Inner ear prosthesis: hear again after decades

Inner ear prosthesis: hear again after decades

After decades of deafness, inner ear implants enable many to hear for the first time

Hearing loss is associated with considerable impairments in everyday life and can only be remedied to a limited extent with conventional hearing aids, which are based on an amplification of the sound impulses. An alternative are so-called cochlear implants (CI), which stimulate the neurons of the cochlea directly. With their help, pigeons can hear again.

Some deaf people have heard sounds for the first time in decades thanks to the inner ear implants. They include Roland Zeh, chief physician of the HTS department (hearing disorders, tinnitus, dizziness and cochlear implants) at the Median Kaiserberg Clinic in Bad Nauheim and president of the German Cochlear Implant Society (DCIG). At the age of seven, the current chief physician suffered a complete loss of hearing in 1967, according to the news portal "Welt Online". The hearing aids that were available at the time could not help him and the doctor lived 30 years in deafness before the first prosthesis was implanted in his inner ear in 1998.

Electrodes stimulate the auditory nerve. The cochlear implant used consists of a microphone and a speech processor, which are attached on the outside and transmit recorded sounds as induction to an implanted receiver as impulses. This sends the impulses to electrodes in the cochlea, which stimulate the auditory nerve. Those affected perceive sounds without activating the so-called hair cells. The DCIG President is quoted by “Welt Online” as saying that the first perception after the operation was “a very impressive experience, almost a sensory overload, but in a positive sense”. It is hardly surprising when someone perceives sounds again for the first time in over 30 years that this is tantamount to a culture shock.

Learn to differentiate the sounds z Like most patients, the DCIG president also needed some time after the operation before he could correctly classify the impulses of the CI. "I first had to learn to differentiate different sounds again," quotes "Welt Online" the chief doctor. With the help of a special hearing training, those affected learn to understand language and even telephone calls are quite possible after a while. "It works better for some, worse for others," explains Prof. Claudia Becker, Head of Sign Language and Audio Pedagogy at the Institute for Rehabilitation Sciences at Humboldt University Berlin in the article by "Welt Online". “After a short period of getting used to it, the CI sounded very pleasant and natural,” the news portal quotes chief physician Roland Zeh. In 2002, due to the success, Zeh also had an implant inserted in the second ear.

Up to 40,000 people in Germany with a cochlear implant Today, according to the DCIG President, between 30,000 and 40,000 people with a cochlear implant live in Germany. Professor Dirk Eßer, chief physician of the department of ear, nose and throat medicine at the Helios Clinic in Erfurt, added to "Welt Online" that 72 such interventions had been carried out in Erfurt last year alone. In a roughly two-hour operation, access to the cochlea is created in order to place the electrode carriers there. The doctors insert the receiver coil directly under the skin, which is connected to the electrode holder. The experts estimate the costs to be 20,000 euros for the implant plus surgery costs as well as costs for the subsequent hearing training and rehabilitation. Health insurers assume costs if conventional hearing aids can no longer understand the spoken language.

Combination of conventional hearing aids with the CI According to the experts, a combination of the CI with hearing aids is also possible, for example if the hearing impaired can only perceive the low tones. The low tones are amplified by the hearing aid and "The CI then makes the high tones, which are important for speech understanding, audible", Roland Zeh reports to "Welt Online". In the case of complete deafness, the conventional hearing aid cannot have any additional benefit.

Use of the CI in children The extent to which the inner ear implants can also be recommended for deaf children was controversial for a long time, according to “Welt Online”. In the article, Prof. Claudia Becker comes to the conclusion that the CI is "a good alternative" but does not offer any security. Previous studies have shown that around half of the children develop natural language acquisition thanks to the CI. The other half showed, despite the CI, considerable developmental delays or impairments in language acquisition. It is therefore important to teach the deaf children sign language anyway, explains Becker. So the children can fall back on them if the implant does not have the desired effect.

Parallel learning of sign language, chief physician Roland Zeh explains in the contribution of “Welt Online” that “children should not be denied the opportunity to listen”. With the help of the inner ear implant, many of them can attend normal school and later have more options when it comes to choosing a career, the DCIG President added. In his view, parallel learning of sign language is still necessary. The question also arises with deaf children from which age a CI should be used at the earliest. This remains controversial in the professional world, says Prof. Claudia Becker. It is therefore unclear whether an appropriate operation should take place before the age of two.

CI not comparable to a healthy ear Professor Dirk Eßer, however, comes to the conclusion that - depending on the time of diagnosis - a CI should also be used before the first year of life. He believes that the intervention should, if possible, take place before the language age. Although the inner ear implants allow a certain amount of hearing, this is by no means comparable to a healthy ear, reports Roland Zeh. "We are still miles away from that," the chief doctor continues to be quoted by "Welt Online". For example, disturbing noises such as traffic noise or other conversations in the same room would make it significantly more difficult for CI wearers to hear, since the implant "unlike the ear can hardly control which sounds it wants to hear," quotes the news portal Prof. Also, the CI cannot help everyone, because at least the auditory nerve must still be intact for this, for example, if it is not properly trained in the womb, CI cannot be used. (fp)

Image: Uschi Dreiucker /

Author and source information

Video: Stanfords Initiative to Cure Hearing Loss