Objective: To monitor cochlear function by extra- and intracochlear electrocochleography (ECoG) during and after cochlear implantation and thereby to enhance the understanding of changes in cochlear function following cochlear implantation surgery. Methods: ECoG responses to acoustic stimuli of 250, 500 and 1,000 Hz were recorded in 9 cochlear implant recipients with presurgical residual hearing. During surgery extracochlear ECoG recordings were performed before and after insertion of the cochlear implant electrode array. After insertion of the electrode array, intracochlear ECoG recordings were conducted using intracochlear electrode contacts as recording electrodes. Intracochlear ECoG recordings were performed up to 6 months after implantation. ECoG findings were correlated with findings from audiometric tests. Results: Extra- and intracochlear ECoG responses could be recorded in all subjects. Extracochlear ECoG recordings during surgery showed moderate changes. Loss or reduction of the ECoG signal at all three frequencies did not occur during cochlear implantation. During the first week following surgery, conductive hearing loss, due to middle ear effusion, led to a decrease in intracochlear ECoG signal amplitudes. This was not attributable to changes of cochlear function. All persistent reductions in ECoG response magnitude after normalization of the tympanogram occurred during the first week following implantation. Thresholds of ECoG signals were at or below hearing thresholds in all cases. Conclusion: Gross intracochlear trauma during surgery appears to be rare. In the early postoperative phase the ability to assess cochlear status by ECoG recordings was limited due to the regular occurrence of middle ear effusion. Still, intracochlear ECoG along with tympanogram recordings suggests that any changes of low-frequency cochlear function occur mainly during the first week after cochlear implantation. ECoG seems to be a promising tool to objectively assess changes in cochlear function in cochlear implant recipients and may allow further insight into the mechanisms underlying the loss of residual hearing.

Tinnitus is a common medical condition which interfaces many different disciplines, yet it is not a priority for any individual discipline. A change in its scientific understanding and clinical management requires a shift toward multidisciplinary cooperation, not only in research but also in training. The European School for Interdisciplinary Tinnitus research (ESIT) brings together a unique multidisciplinary consortium of clinical practitioners, academic researchers, commercial partners, patient organizations, and public health experts to conduct innovative research and train the next generation of tinnitus researchers. ESIT supports fundamental science and clinical research projects in order to: (1) advancing new treatment solutions for tinnitus, (2) improving existing treatment paradigms, (3) developing innovative research methods, (4) performing genetic studies on, (5) collecting epidemiological data to create new knowledge about prevalence and risk factors, (6) establishing a pan-European data resource. All research projects involve inter-sectoral partnerships through practical training, quite unlike anything that can be offered by any single university alone. Likewise, the postgraduate training curriculum fosters a deep knowledge about tinnitus whilst nurturing transferable competencies in personal qualities and approaches needed to be an effective researcher, knowledge of the standards, requirements and professionalism to do research, and skills to work with others and to ensure the wider impact of research. ESIT is the seed for future generations of creative, entrepreneurial, and innovative researchers, trained to master the upcoming challenges in the tinnitus field, to implement sustained changes in prevention and clinical management of tinnitus, and to shape doctoral education in tinnitus for the future.

To assess cochlear trauma during cochlear implantation by electrocochleography (ECoG) and cone beam computed tomography (CBCT) and to correlate intraoperative cochlear trauma with postoperative loss of residual hearing. ECoG recordings to tone bursts at 250, 500, 750, and 1000 Hz and click stimuli were recorded before and after insertion of the cochlear implant electrode array, using an extracochlear recording electrode. CBCTs were conducted within 6 weeks after surgery. Changes of intraoperative ECoG recordings and CBCT findings were correlated with postoperative threshold shifts in pure-tone audiograms. Fourteen subjects were included. In three subjects a decrease of low-frequency ECoG responses at 250, 500, 750, and 1000 Hz occurred after insertion of the electrode array. This was associated with no or minimal residual hearing 4 weeks after surgery. ECoG responses to click stimuli were present in six subjects and showed a decrease after insertion of the electrode array in three. This was associated with a mean hearing loss of 21 dB in postoperative pure-tone audiograms. Scalar dislocation of the electrode array was assumed in one subject because of CBCT findings and correlated with a decrease of low-frequency ECoG responses and a complete loss of residual hearing. Hearing loss of ≤11 dB is not associated with detectable decrease in ECoG recordings during cochlear implantation. However, in a majority of patients with threshold shifts of >11 dB or complete hearing loss, an intraoperative decrease of high- or low-frequency ECoG signals occurs, suggesting acute cochlear trauma.

With the placement of a floating mass transducer (FMT) at the round window, a new approach of coupling an implantable hearing system to the cochlea has been introduced. The aim of the present experimental study is to examine the influence of different ways of FMT placement at the round window on the vibration energy transfer to the cochlea. Experiments were performed on 8 ears of human whole head specimens. A mastoidectomy and facial recess approach were performed to access the middle ear structures. Seven different conditions were compared, that is, a perpendicular or 90-degree rotated position of the FMT in the round window niche, overlaid or underlaid with connective tissue or with tight fixation and disrupted ossicular chain. The FMT was stimulated electrically and the movements at the FMT, the stapes head, and the promontory were measured using laser Doppler vibrometry. Vibration transmission to the cochlear fluids was best with the FMT placed perpendicular to the round window membrane and underlaid with connective tissue. The energy transfer to the inner ear was up to 45 dB higher compared with tight fixation condition, where the poorest energy transfer was found. Underlaying the FMT with connective tissue improved energy transfer even for a suboptimal orientation of the FMT. The way of coupling of the FMT to the round window has a substantial influence on the vibration transmission. Energy transfer to the inner ear is highest with the FMT placed in the round window and underlaid with tissue.

Objective: The aims of this study were: (1) To investigate the correlation between electrophysiological changes during cochlear implantation and postoperative hearing loss, and (2) to detect the time points that electrophysiological changes occur during cochlear implantation. Material and Methods: Extra- and intracochlear electrocochleography (ECoG) were used to detect electrophysiological changes during cochlear implantation. Extracochlear ECoG recordings were conducted through a needle electrode placed on the promontory; for intracochlear ECoG recordings, the most apical contact of the cochlear implant (CI) electrode itself was used as the recording electrode. Tone bursts at 250, 500, 750, and 1000 Hz were used as low-frequency acoustic stimuli and clicks as high-frequency acoustic stimuli. Changes of extracochlear ECoG recordings after full insertion of the CI electrode were correlated with pure-tone audiometric findings 4 weeks after surgery. Results: Changes in extracochlear ECoG recordings correlated with postoperative hearing change (r = −0.44, p = 0.055, n = 20). Mean hearing loss in subjects without decrease or loss of extracochlear ECoG signals was 12 dB, compared to a mean hearing loss of 22 dB in subjects with a detectable decrease or a loss of ECoG signals (p = 0.0058, n = 51). In extracochlear ECoG recordings, a mean increase of the ECoG signal of 4.4 dB occurred after opening the cochlea. If a decrease of ECoG signals occurred during insertion of the CI electrode, the decrease was detectable during the second half of the insertion. Conclusion: ECoG recordings allow detection of electrophysiological changes in the cochlea during cochlear implantation. Decrease of extracochlear ECoG recordings during surgery has a significant correlation with hearing loss 4 weeks after surgery. Trauma to cochlear structures seems to occur during the final phase of the CI electrode insertion. Baseline recordings for extracochlear ECoG recordings should be conducted after opening the cochlea. ECoG responses can be recorded from an intracochlear site using the CI electrode as recording electrode. This technique may prove useful for monitoring cochlear trauma intraoperatively in the future.