Objectives: To compare intraoperative intracochlear electrocochleography (ECochG) with hearing preservation outcomes in cochlear implant (CI) subjects. Design: Intraoperative electrocochleography was performed in adult CI subjects who were recipients of Advanced Bionics’ Bionics LLC precurved HiFocus MidScala or straight HiFocus SlimJ electrode arrays. ECochG responses were recorded from the most apical electrode contact during insertion. No changes to the insertions were made due to ECochG monitoring. No information about insertion resistance was collected. ECochG drops were estimated as the change in amplitude from peak (defined as maximum amplitude response) to drop (largest drop) point after the peak during insertion was measured following the peak response. Audiometric thresholds from each subject were obtained before and approximately 1 month after CI surgery. The change in pure tone average for frequencies between 125 Hz and 500 Hz was measured after surgery. No postoperative CT scans were collected as part of this study. Results: A total of 68 subjects from five surgical centers participated in the study. The study sample included 30 MidScala and 38 SlimJ electrodes implanted by approximately 20 surgeons who contributed to the study. Although a wide range of results were observed, there was a moderate positive correlation (Pearson Correlation coefficient, r = 0.56, p < 0.01) between the size of the ECochG drop and the magnitude of pure tone average change. This trend was present for both the MidScala and SlimJ arrays. The SlimJ and MidScala arrays produced significantly different hearing loss after surgery. Conclusion: Large ECochG amplitude drops observed during electrode insertion indicated poorer hearing preservation. Although the outcomes were variable, this information may be helpful to guide surgical decision-making when contemplating full electrode insertion and the likelihood of hearing preservation.

Although cochlear implants (CI) traditionally have been used to treat individuals with bilateral profound sensorineural hearing loss, a recent trend is to implant individuals with residual low-frequency hearing. Patients who retain some residual acoustic hearing after surgery often can benefit from electro-acoustic stimulation (EAS) technologies, which combine conventional acoustic amplification with electrical stimulation. However, interactions between acoustic and electrical stimulation may affect outcomes adversely and are time-consuming and difficult to assess behaviorally. This study demonstrated the feasibility of using the Advanced Bionics HiRes 90K Advantage implant electronics and HiFocus Mid Scala/1j electrode to measure electrocochleography (ECochG) responses in the presence of electrical stimulation to provide an objective estimate of peripheral physiologic EAS interactions. In general, electrical stimulation reduced ECochG response amplitudes to acoustic stimulation. The degree of peripheral EAS interaction varied as a function of acoustic pure tone frequency and the intra-cochlear location of the electrically stimulated electrode. Further development of this technique may serve to guide and optimize clinical EAS system fittings in the future.

Although cochlear implants (CI) traditionally have been used to treat individuals with bilateral profound sensorineural hearing loss, a recent trend is to implant individuals with residual low-frequency hearing. Notably, many of these individuals demonstrate an air-bone gap (ABG) in low-frequency, pure-tone thresholds following implantation. An ABG is the difference between audiometric thresholds measured using air conduction (AC) and bone conduction (BC) stimulation. Although behavioralbehavioral AC thresholds are straightforward to assess, BC thresholds can be difficult to measure in individuals with severe-to-profound hearing loss because of vibrotactile responses to high-level, low-frequency stimulation and the potential contribution of hearing in the contralateral ear. Because of these technical barriers to measuring behavioral BC thresholds in implanted patients with residual hearing, it would be helpful to have an objective method for determining ABG. This study evaluated an innovative technique for measuring electrocochleographic (ECoG) responsesusing the cochlear microphonic (CM) response to assess AC and BC thresholds in implanted patients with residual hearing. Results showed high correlations between CM thresholds and behavioral audiograms for AC and BC conditions, thereby demonstrating the feasibility of using ECoG as an objective tool for quantifying ABG in CI recipients.

Objectives: During cochlear implant (CI) electrode placement, single low-frequency (e.g., 500 Hz) cochlear microphonics (CM) measurements are used to monitor hair-cell function and provide feedback to avert insertion trauma. However, it can be difficult to differentiate between trauma and the electrode’s progression through the cochlea when monitored with a single frequency. Multi-frequency CM measurements, while more complex to analyze, can provide more accurate feedback by measuring CM from various locations along the basilar membrane. Methods: A new algorithm was developed to analyze multi-frequency CM tracings by comparing amplitude and phase changes across different test frequencies. The new algorithm was evaluated as to its ability to identify drop-alarm instances with the multi-frequency approach, as compared to single-frequency 500 Hz tracings. Results: The algorithm presented in this manuscript uses the relationship between CM amplitude and phase changes across frequencies to provide real-time feedback during CI electrode placement. The results show that multi-frequency CM tracings raised an alarm only 0.5 times, as compared to 2.8 instances of alarm raised for the single-frequency 500 Hz CM measurements. Conclusions: Multi-frequency CM tracings can help reduce the number of alarms which may be false positives prompting unnecessary electrode manipulations, thereby minimizing the risk of insertion trauma.

Objectives: Tip fold-over (TFO) is a rare but critical occurrence in cochlear implant procedures where the electrode array folds back on itself within the cochlea, compromising programming and device performance. Timely intraoperative detection is essential for immediate correction and optimal placement. Electric field imaging (EFI) has shown promise for identifying TFO both intra- and post-operatively. This study evaluates the performance of a TFO detection algorithm implemented in Target CI (Version 1.6) using Advanced Bionics’ cochlear implant systems, validated through bench and patient datasets. Methods: Sample data included (1) bench testing with a plastic cochlea and human temporal bones with and without induced TFOs, confirmed visually or radiographically; (2) intraoperative EFI measurements recorded using the AIM™ system, with electrode placement confirmed through imaging; and (3) historical EFI recordings from the Target CI DataLake, which lacks imaging and programming metadata. The TFO algorithm’s performance was evaluated by assessing its sensitivity and specificity using these datasets. Results: The TFO algorithm achieved 100% sensitivity and specificity in bench models and intraoperative EFI with imaging-confirmed placements. Among 226 intra-op cases, four TFOs were confirmed by imaging, and all were correctly identified by the algorithm. In the large set of DataLake cases (14,734 implants), 0.80% were flagged as potential TFOs. TFO prevalence was higher with pre-curved arrays (1.22%) than straight lateral wall arrays (0.32%). Conclusions: The TFO algorithm showed high reliability with 100% sensitivity and specificity using routine clinical EFI data. While not a replacement for imaging, the TFO algorithm serves as a fast, accessible tool to alert clinicians to potential TFOs.

Objectives: Extracochlear electrodes (EEs), defined as electrode contacts located outside the cochlea, can degrade cochlear implant (CI) performance. We present and validate an Electric Field Imaging (EFI)-based algorithm that helps detect EEs and can be used intra- or post-operatively. Methods: An algorithm for detecting EEs from EFI data was developed. Validation and testing were performed using three datasets: (a) bench models with known EE conditions (saline and resistive load model), (b) clinical EFI recordings from CI recipients with imaging confirmation (CT or plain X-ray), and (c) EFI recordings without imaging. Primary outcomes included the ability to differentiate extracochlear conditions from fully inserted electrode arrays, as well as the concordance between the number of EE contacts identified by the algorithm and those determined from controlled bench configurations or available imaging data. Results: The algorithm reliably differentiated full insertion from EE conditions on bench models and clinical EFI recordings from CI recipients with imaging confirmation. In the imaging-confirmed clinical cohort (6 EE cases among 226 CI recipients), the algorithm achieved 100% sensitivity and specificity. In clinical cases without imaging, the algorithm flagged 3.94% as having extracochlear electrodes, within the range of prevalence reported in the literature. Furthermore, the lateral-wall electrode arrays were associated with a significantly higher extracochlear electrode occurrence compared to the pre-curved arrays. Conclusions: This EFI-based algorithm may provide a useful screening tool for EEs using routine clinical measurements, supporting intra-operative and post-operative detection while reducing reliance on imaging and thereby aiding clinical decision-making. The method can be integrated into existing clinical fitting software workflow and complements recent work on EFI-based tip fold-over detection. The observed sensitivity and specificity suggest that this approach may provide a valuable tool for identifying EEs in situations where imaging is unavailable or impractical.