Groundbreaking implant eliminates external processors, offering a seamless, high-performance solution for hearing loss sufferers.
Research: Rehabilitation of human hearing with a totally implantable cochlear implant: a feasibility study. Image Credit: decade3d – anatomy online / Shutterstock
Scientists have developed a totally implantable cochlear implant capable of providing high-level hearing performance comparable to that of conventional cochlear implants with external audio processors. The study is published in the journal Communications Medicine.
Background
Hearing is vital for social communication, perceiving, and navigating the surrounding environment. People with severe-to-profound hearing loss experience a range of emotional distress, including low self-esteem and confidence and loneliness due to social isolation.
Cochlear implants are neuroprosthetic devices used to restore hearing in individuals with severe-to-profound hearing loss. These devices use an externally worn audio processor that detects and encodes sounds as electrical signals, which are transmitted to the implant to stimulate the auditory nerve.
Despite significant benefits, the uptake of cochlear implants remains low worldwide. The World Health Organization estimates that over 60 million people globally have severe-to-profound hearing loss, but only around 1 million cochlear implants have been performed to date. The main reason behind this is the external audio processor, which requires cleaning, maintenance, and additional peripherals to operate. The external device also interferes with daily activities like bathing and swimming and may act as a visible marker of disability, impacting self-esteem.
In response to these challenges, researchers developed a totally implantable cochlear implant (TICI) and assessed its safety and efficacy profiles in individuals with bilateral severe-to-profound hearing loss. This study is significant as a first-in-human trial and represents a milestone in the field.
Study Design
The study included six adult participants with bilateral severe-to-profound hearing loss who got no benefit or limited benefit from conventional hearing aids. Among participants, one had sudden hearing loss, and five had progressive hearing loss.
The study was conducted at the University Hospital Center 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 subdermal microphone, implantable power supply, and transdermal wireless data link, were integrated into a single implant that was invisible to 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 Safety Profile of the Device
The study reported 15 adverse events during the follow-up period. Nine of these events were categorized as adverse device effects, one of which was an anticipated serious adverse device effect characterized by swelling and infection at the site of implantation.
This adversity was resolved after treatment without further consequences. No unanticipated serious adverse device effects occurred during the study period.
Efficacy Profile of the Device
The study performed monosyllabic word recognition to test speech perception in quiet and noise. The findings revealed that the totally implantable cochlear implant and the external audio processor have comparable scores for speech perception in quiet and noise.
The study used four widely used instruments to evaluate patient-reported outcomes: the Health Utilities Index mark 3 (HUI3), the 12-item form of the Speech, Spatial, and Qualities of Hearing scale (SSQ-12), the Hearing Implant Sound Quality Index (HISQUI-19), and the Nijmegen Cochlear Implant Questionnaire (NCIQ).
The study found a gradual increase in all scores over the study duration for participants implanted with the implantable cochlear device. For example, HUI3 scores improved from a median of 0.45 pre-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.
The analysis of device usage statistics revealed that all participants except one used the implantable cochlear implant without an external audio processor most of the time.
Study Significance
The study describes the development and validation of a totally implantable cochlear implant capable of providing high-level hearing performance similar to that of conventional cochlear implants carrying external audio processors.
The newly developed device, which can be implanted via conventional surgical methods, can significantly improve users’ quality-of-life outcomes and speech perception in quiet and noise.
The study emphasizes that, unlike earlier fully implantable cochlear devices, this device offers hearing performance with internal components comparable to using an external processor.
The implant’s safety analysis indicates a comparable profile to that of conventional cochlear implants with external audio processors. One anticipated serious adversity observed during the study period completely resolved after treatment.
Regarding usage time, the study finds that five out of six participants used the implant considerably 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.
Considering the findings of this preliminary study, scientists believe that such implants can open up a range of options for treating hearing loss. However, due to the small sample size, they could not conduct robust inferential statistics to assess the outcomes.
The authors highlighted the exploratory nature of this study, noting that first-in-human trials are inherently limited in scale and must proceed cautiously to ensure safety.
This device represents a significant step forward, with lessons learned potentially informing larger-scale trials and advancing the field of cochlear implant research.
