Human Feasibility Study of an Implantable Middle Ear Microphone (SIME)
Research type
Research Study
Full title
Human Feasibility Study of an Implantable Middle Ear Microphone (SIME)
IRAS ID
186571
Contact name
Philip Begg
Contact email
Sponsor organisation
University Hospitals Birmingham NHS Foundation Trust
Duration of Study in the UK
1 years, 5 months, 1 days
Research summary
Research Summary:
Cochlear implants have been used for some time in the treatment of those with severe or profound hearing loss. The use of these implantable devices has enabled those with severe hearing impairment to develop and participate in the day to day life of their families, education and workplace. The current design of the cochlear implant is less cumbersome than the early models, which included a body worn component, with a behind the ear component being the only visible part. However, the technology now available, begs the questions why does there have to be any external part?
Why can't the entire implant be hidden in the ear or under the skin?
One of the major challenges of implantable devices for hearing loss is
where to position the microphone that collects the sound to send to the processor, to allow the totally implantable device to be developed.
Currently the microphone is part of the behind-the-ear sound processor. The focus of the proposed project is a collaboration between clinicians, academics and partners in industry to develop a microphone that can be accurately placed in the most suitable position in the ear, to ensure that the instrument has the best possible outcomes for the patient in sound quality and in achieving a safer and more socially acceptable outcome. The effect of this will be to increase confidence and to reduce the stigma of those who
have traditionally worn an implant which is more visible.
A further priority for the project will be to work with patients, carers and potential implant candidates in the project patient focus group to ensure there is an informed development of the project, from a patient perspective. This will be achieved through regular meetings of the focus group throughout the project timetable.Summary of Results:
The project was successful in answering the research questions. Cadaveric work enables us to understand the mechanisms of both the placement of the microphone and how it may behave once implanted. This phase of the project enabled the team to design a safe surgical phase of the trial and conclude how best to optimise the most effective placements of the middle ear microphone.Through these conclusions the team were able to successfully implant six patients. Following the 6 months of using the microphone, all were ex-planted and all of the microphones were stable and safe throughout. In the case of patient number 5, due to unforeseen medical issues of a completely separate matter, the microphone was insitu for 8 months and there were no reported issues from the patient, and on ex-plantation the microphone was still safely insitu and functioning well.
The designed surgical procedure for the implantation of the experimental device added on average 60 minutes to the implant procedure, this was mainly down to the fixation device and intraoperative testing, which in a standard cochlear implant would not be necessary. It is unlikely that this would be necessary in a final product that was brought to market.
The tube microphone was well tolerated insitu and patients were not aware of any residual physiological noises, although one patient did report a background hissing sound when the microphone was active.
The connecting pedestal, which was used to connect the experimental device to the patients existing cochlear implant, required some management, mainly cleaning and ensuring it was kept dry. This would not be an issue in a modified implant if fully integrated.
The main methodology for determining the efficacy of the microphone was during the audiological testing phase, this showed that the tube microphone behaved as well as the external microphone at high intensities (70dB), however at lower intensities (55dB) it performed slightly below or as well as the external microphone. However, subjectively patients reported little difference in the quality of sound and their ability to hear well.
Overall, the study was a success, it proved that a tube microphone could be implanted in a human, safely and effectively.
This is a critical stage of the research findings, as it is clear that the tube microphone will enable the development of a Totally Implantable Cochlear Implant (TICI), which will be a complete change in the way that CI’s are regarded.
Follow on research is still required to perfect the fixation device and improve on the methodology for placement; it may also be possible to improve the microphone further and perhaps reduce the weight and size of the microphone. It would also be a considerable challenge to design this system further to enable this to be used in children, mainly in coping with the effects of growth from child to adult and the impact on the temporal bone.
REC name
HSC REC A
REC reference
17/NI/0012
Date of REC Opinion
9 Feb 2017
REC opinion
Further Information Favourable Opinion