Extra-flat hearing implant expands application possibilities

A team from the University Medicine Halle has been involved in the development of an extra-flat, bone-anchored hearing system for many years. Prof. Stefan Plontke performed the first regular implantation of the new device following its approval for clinical use. In an interview with MEDICA-tradefair.com, he presents the new development together with Prof. Torsten Rahne.

Prof. Plontke, can you briefly describe your task within the project?

Prof. Stefan Plontke: We were involved in the development of a bone conduction implant. It is used when sound can no longer reach the still-functioning cochlea via the eardrum and ossicles. The solution complements the various hearing systems.

Conventional hearing aids simply amplify the sound that is transported to the cochlea. There, electrical nerve impulses are generated from mechanical vibrations. If the sound cannot reach the cochlea in the normal way due to malformations or other diseases, or if the amplification of the cochlea is not sufficient, hearing implants come into play. If the cochlea is still functioning, the sound is transmitted from the implant via the skull bone or the middle ear to the cochlea, where it is converted into electrical nerve impulses. Another group, the cochlear implants, replaces a non-functioning sound conversion in the cochlea. This solution does not work with sound, but with electricity.

What did your collaboration look like?

Plontke: We work as a team to enable patients to make a good decision. I keep an eye on the surgical and anatomical aspects. Prof. Rahne is an audiologist; as a physicist and neuroscientist, he focuses on the physical and technical parameters and knows which implant provides the best hearing result. In addition to the surgical and technical aspects, the patient's wishes also play a very important role.

What were the challenges in this development?

Prof. Torsten Rahne : Typically, the transmission of sound to the skull bone requires a large mass of the transmission device. However, there is only enough space for this in the skull bone in some places, especially in children and people with malformations. With our cooperation, the University of Gothenburg has succeeded in integrating a very powerful transducer into a very flat implant. The flatter design means that significantly less bone material needs to be removed for the implant site than before.

Thanks to improved signal processing and an improved transducer, the new implant can deliver energy to the bone with the same strength and power as previous implants. The external audio processor is magnetically attached to the outside of the skull. This is where the sound signals from the environment are pre-processed, and background noise is filtered out. Our first patient has confirmed our expectations that everything can be heard crystal clear after the operation.

What role did your evaluations of the skull scans play in the development?

Rahne: In cooperation with the radiology clinic, we examined around 200 MRI and CT scans from our database in different age groups, a third of which were from children. In particular, the part of the skull where the implant is located grows with increasing age. We then carried out a virtual implantation of this new implant for the different age groups and determined in how many cases it fits. In our study, we were able to show that the bone thickness is sufficient for the new implant and its fixation from the age of nine. Our work contributed to the fact that we ended up with a shape that fits almost every skull. The implant was developed by researchers at Chalmers University in Gothenburg, who created the prototype.

How do you classify these improvements in the context of possible treatments?

Plontke: These implants are not intended to replace traditional ear surgery or hearing aids. They are intended to fill a gap in the care process so that, as far as possible, no one has to live with a hearing impairment because there is no suitable implant. The indication must be carefully considered; this is an interdisciplinary task. This implant is chosen above all when the anatomical conditions are challenging, for example in the case of a thin skull, where the meninges are quickly reached. Interdisciplinary collaboration between audiologists and surgeons is also important to us.