The revolutionary implant eliminates external processors, providing a seamless, high-performance solution for people suffering from hearing loss.
Research: Rehabilitation of human hearing with a fully implantable cochlear implant: a feasibility study. Image credit: decade3d – anatomy online/Shutterstock
Scientists have developed a fully implantable cochlear implant capable of providing high-level hearing performance comparable to conventional cochlear implants with external audio processors. The study is published in the journal Communication medicine.
Background
Hearing is vital for social communication, perception, and environmental navigation. People with severe to profound hearing loss experience a range of emotional distress, including low self-esteem, low self-confidence, and loneliness due to social isolation.
Cochlear implants are neuroprosthetic devices used to restore hearing in people with severe to profound hearing loss. These devices use an externally worn audio processor that detects and encodes sounds into electrical signals, which are transmitted to the implant to stimulate the auditory nerve.
Despite significant benefits, adoption of cochlear implants remains low worldwide. The World Health Organization estimates that more than 60 million people worldwide have severe to profound hearing loss, but only about 1 million cochlear implants have been performed to date. The main reason for this is the external audio processor, which requires cleaning, maintenance, and additional peripherals to function. The external device also interferes with daily activities such as bathing and swimming and can act as a visible marker of disability, impacting self-esteem.
In response to these challenges, researchers developed a totally implantable cochlear implant (TICI) and evaluated its safety and effectiveness profiles in people with severe to profound bilateral hearing loss. This study is important as a first-in-human trial and represents a milestone in the field.
Study design
The study included six adult participants with severe to profound bilateral hearing loss who experienced no or limited benefit from conventional hearing aids. Of the participants, one had sudden hearing loss and five had progressive hearing loss.
The study was carried out at the University Hospital of Liège, Belgium, and the University Hospital of Munich, Germany. Information on adverse events, speech perception in quiet and noise, patient-reported outcomes, and device usage statistics was collected over 52 weeks after implantation.
All components of the device (Mi2000), including the subcutaneous microphone, implantable power supply and wireless transdermal data link, have been integrated into a single implant invisible from the outside.
Four participants had the device surgically implanted on the left side and two participants had it implanted on the right side. Each participant was examined with an implantable cochlear implant (Mi2000) and an external audio processor.
The device security profile
The study reported 15 adverse events during the follow-up period. Nine of these events were classified as adverse device reactions, one of which was an expected serious adverse event of the device, characterized by swelling and infection at the implantation site.
This adversity was resolved after treatment without further consequences. No serious, unanticipated adverse device effects occurred during the study period.
Device efficiency profile
The study performed monosyllabic word recognition to test speech perception in quiet and noise. The results revealed that the fully implantable cochlear implant and the external audio processor had comparable speech perception scores in quiet and noise.
The study used four widely used instruments to assess patient-reported outcomes: the Health Utilities Index mark 3 (HUI3), the 12-item form of the Speech, Spatial, and Hearing Qualities Scale (SSQ- 12), the sound scale of the hearing implant. Quality Index (HISQUI-19) and Nijmegen Cochlear Implant Questionnaire (NCIQ).
The study found a progressive increase in all scores over the duration of the study for participants implanted with the implantable cochlear device. For example, HUI3 scores improved from a median of 0.45 before implantation to 0.85 at the end of the study, reflecting a substantial improvement in quality of life. A similar increase was observed for participant-reported satisfaction scores.
Analysis of device usage statistics revealed that all but one participant used the implantable cochlear implant most of the time without an external audio processor.
Significance of the study
The study describes the development and validation of a fully implantable cochlear implant capable of providing high-level hearing performance similar to that of conventional cochlear implants equipped with external audio processors.
The newly developed device, which can be implanted via conventional surgical methods, can significantly improve users’ quality of life and speech perception in quiet and noise.
The study highlights that, unlike previous fully implantable cochlear devices, this device provides hearing performance with internal components comparable to using an external processor.
Safety analysis of the implant indicates a profile comparable to that of conventional cochlear implants equipped with external audio processors. An expected serious adversity observed during the study period resolved completely after treatment.
Regarding duration of use, the study reveals that five out of six participants used the implant much more frequently without an external processor than with an external processor. Only one participant preferred to use the external processor. However, this participant mentioned using the implant with the external processor only at home and not in public places.
Given the results of this preliminary study, scientists believe that such implants may open up a range of options for treating hearing loss. However, due to the small sample size, they were unable to perform robust inferential statistics to evaluate the results.
The authors emphasized the exploratory nature of this study, noting that first-in-human trials are inherently limited in scale and should be carried out with caution to ensure safety.
This device represents a significant advance, with lessons learned potentially informing larger-scale trials and advancing the field of cochlear implant research.
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