DEPARTMENT OF HEARING IMPLANT SCIENCES
SHINSHU UNIVERSITY SCHOOL OF MEDICINE
Hearing Implants
Cochlear implantation (CI), which involves the insertion of the electrode into the cochlea and direct electrical stimulation of the auditory nerve, is currently the standard therapeutic option for severe-to-profound sensorineural hearing loss patients worldwide. The use of hearing implants including cochlear implants, electric acoustic stimulation (EAS) and middle ear implants is growing rapidly due to the associated benefits in terms of improved hearing. The development of new devices supported by basic research as well as clinical research programs is essential for further progress in this field. We e are undertaking several basic research and clinical research programs on Hearing Implants and related scientific fields including the genetic background of CI patients and their auditory performance.
Clinical research on Hearing Implants and approval obtained
We are undertaking several clinical research programs on hearing implants and obtained government approval for social insurance-based treatment. The most remarkable result involves or obtaining EAS approval in Japan prior to FDA approval.
2010-2014 Advanced medical care B program for Electrical Acoustic Stimulation (EAS).
2013 Approval of EAS.
2012-2014 Clinical trial for middle ear implants (Vibrant Sound Bridge: VSB).
2015 Approval of VSB.
2012-2014 Clinical research for cochlear implantation in single-sided deafness (SSD).
2013-2016 Clinical research for BoneBridge (BB).
2017-2020 Clinical research on ADHEAR.
2020 Approval of BB.
2021 Approval of ADHEAR.
2021 - Advanced medical care B program for CI in SSD.
We have published many scientific papers on hearing implants and identified several novel findings including the auditory outcomes for CI or EAS for each genetic cause of deafness, the hearing preservation outcomes with longer electrode (Yoshimura et al., Acta Otolaryngol. 2020A: Figure 1), hearing preservation and the etiology of hearing loss (Yoshimura et al., Acta Otolaryngol. 2020B: Figure 2), the effect of CI insertion on vestibular function, and so on.
Figure 1. Individual air-conduction hearing thresholds. The dashed and solid lines indicate pre- and 6 months post-op, respectively.
Electrode array illustrations represent insertion depth.
Figure 2. Average pre- (blue line) and post-operative (red line) air conduction hearing thresholds for patients with (A) pathogenic variants in the CDH23, MYO7A, or MYO15A gene, and (B) hearing loss due to other causes. (C) A comparison of HP scores in each group. Median, interquartile, minmum and maximum scores for the HP scale. Statistical analysis by Mann–Whitney test.
Basic research on hearing implants
We have also performed basic research on gene expression changes in association with dexamethasone eluting CI electrodes. The results revealed that gene expression, including that of some inflammation factors, was changed after conventional CI insertion, and this change was suppressed when using dexamethasone eluting electrodes (Takumi et al., PLoS One 2014. Figure 3).
Figure 3. Changes in up- and down-regulation of gene expression with insertion of normal and dexamethasone-eluting electrode insertion. Up-regulation was 2-fold or more, and down-regulation was 2-fold or less, with normal electrode insertion compared to non-surgically treated controls.