Cochlear implant positioning and fixation

Hearing loss is one of the most common conditions worldwide. Almost half a billion people globally suffer from disabling hearing loss, and this number is expected to increase in the coming years. Hearing aids are often helpful, but in cases of severe hearing loss, a cochlear implant (CI) may be considered. The CI takes over the function of damaged nerve cells by converting sound into electrical signals. The surgery required to place the CI, known as cochlear implantation, is a safe procedure with few complications. The surgical techniques used to secure the implant under the skin and in the cochlea vary between centers and CI surgeons. Increasingly, operators are using minimally invasive surgery, although there is no consensus among CI surgeons regarding the safety of these newer techniques. Despite the many advantages of minimally invasive techniques, there seems to be insufficient scientific evidence to safely use these methods. Incorrect positioning and inadequate fixation of the CI can lead to implant displacement, also known as migration. In this thesis, we have investigated the surgical techniques used during cochlear implantation to secure the CI, with a specific focus on complications related to drilling a bony recess and implant migration under the skin. We have developed new methods to position the implant, utilizing 3-D software and 3-D printing. Finally, we have attempted to develop objective means to determine CI migration and to map the impact of wearing a CI on patients.