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Kim JS, Hong SH, Moon IJ. Association Between Intracochlear Electrode Design and Electrically-Evoked Compound Action Potential Measures in Cochlear Implant Users. Otolaryngol Head Neck Surg 2024; 171:849-857. [PMID: 38774957 DOI: 10.1002/ohn.799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 03/09/2024] [Accepted: 04/13/2024] [Indexed: 08/28/2024]
Abstract
OBJECTIVE Cochlear implant (CI) electrode design has changed over time. Changes in intracochlear electrode design might influence the spread of neural activation along the auditory nerve and the number of independent channels. This study aimed to investigate the impact of intracochlear electrode design on the electrode-neuron interface using electrophysiological measures. STUDY DESIGN Prospective cohort study. SETTING A single tertiary hospital. METHODS Fifty-two ears who were implanted with CI divided into 3 groups based on the design of intracochlear electrode arrays. Twenty-three ears were implanted with lateral wall straight electrodes. Eighteen ears were implanted with the slim perimodiolar electrode, and 11 ears were implanted with the old perimodiolar electrode. Various electrically-evoked compound action potential (ECAP) metrics were measured to quantify spread of excitation and channel interaction. RESULTS ECAP threshold and slope were not significantly different among groups. ECAP spread of excitation (SOE) half-width and channel interaction index (CII) were significantly larger in subjects implanted with the lateral wall straight electrodes, indicating a wider spread of excitation compared to those with perimodiolar electrodes. Electrode impedance was significantly lower in subjects implanted with perimodiolar electrodes than those with lateral wall electrodes. CONCLUSION Perimodiolar electrode groups yielded significantly narrower SOE half-widths and smaller CII than the lateral wall straight electrode group. This may indicate that the electrode array that hugged the modiolus had less overlap in neural excitation between adjacent electrodes, resulting in reduced channel interaction and potentially better spectral resolution than the electrode array positioned more laterally.
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Affiliation(s)
- Jeong-Seo Kim
- Hearing Research Laboratory, Samsung Medical Center, Seoul, South Korea
- Medical Research Institute, Sungkyunkwan University, Suwon, South Korea
- Department of Speech-Language Pathology and Aural Rehabilitation, Woosong University, Daejeon, South Korea
| | - Sung Hwa Hong
- Hearing Research Laboratory, Samsung Medical Center, Seoul, South Korea
- Soree Ear Clinic, Seoul, South Korea
| | - Il Joon Moon
- Hearing Research Laboratory, Samsung Medical Center, Seoul, South Korea
- Department of Otolaryngology-Head and Neck Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
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Meuser M, Schwitzer S, Thiele M, Boyle P, Ernst A, Basta D. Intra-Cochlear Electrode Position Impacts the Preservation of Residual Hearing in an Animal Model of Cochlear Implant Surgery. Audiol Neurootol 2024:1-11. [PMID: 38981457 DOI: 10.1159/000540266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Accepted: 07/07/2024] [Indexed: 07/11/2024] Open
Abstract
INTRODUCTION Preservation of residual hearing after cochlear implantation remains challenging. There are several approaches to preserve residual hearing, but the configuration of the implant electrode array seems to play a major role. Lateral wall electrode arrays are seemingly more favorable in this context. To date, there are no experimental data available which correlate the spatial electrode position in the scala tympani with the extent of hearing preservation. METHODS Based on micro-computed tomography (µCT) imaging data, this study analyses the exact position of a pure silicone electrode array inserted into the cochlea of four guinea pigs. Array position data were correlated with the extent of hearing loss after implantation, measured using auditory brainstem measurements in the frequency range of the area occupied by the electrode array area as well as apical to the array. RESULTS The use of pure silicone arrays without electrodes resulted in artifact-free, high-resolution µCT images that allowed precise determination of the arrays' positions within the scala tympani. The electrode arrays' locations ranged from peri-modiolar to an anti-modiolar. These revealed a correlation of a lower postoperative hearing loss with a higher spatial proximity to the lateral wall. This correlation was found in the low-frequency range only. A significant correlation between the inter-individual differences in the diameter of the scala tympani and the postoperative hearing loss could not be observed. CONCLUSION This study demonstrates the importance of the intra-cochlear electrode array's position for the preservation of residual hearing. The advantage of such an electrode array's position approximated to the lateral wall suggests, at least for this type of electrode array applied in the guinea pig, it would be advantageous in the preservation of residual hearing for the apical part of the cochlea, beyond the area occupied by the electrode array.
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Affiliation(s)
- Max Meuser
- Department of Otolaryngology at ukb, Charité Medical School, University of Berlin, Berlin, Germany
| | - Susanne Schwitzer
- Department of Otolaryngology at ukb, Charité Medical School, University of Berlin, Berlin, Germany
| | - Mario Thiele
- Julius Wolff Institute, Center for Musculoskeletal Biomechanics and Regeneration, Charité Medical School, University of Berlin, Berlin, Germany
| | - Patrick Boyle
- Advanced Bionics GmbH, European Research Centre, Hanover, Germany
| | - Arne Ernst
- Department of Otolaryngology at ukb, Charité Medical School, University of Berlin, Berlin, Germany
| | - Dietmar Basta
- Department of Otolaryngology at ukb, Charité Medical School, University of Berlin, Berlin, Germany
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Zhang L, Schmidt FH, Oberhoffner T, Ehrt K, Cantré D, Großmann W, Schraven SP, Mlynski R. Transimpedance Matrix Can Be Used to Estimate Electrode Positions Intraoperatively and to Monitor Their Positional Changes Postoperatively in Cochlear Implant Patients. Otol Neurotol 2024; 45:e289-e296. [PMID: 38346796 DOI: 10.1097/mao.0000000000004145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2024]
Abstract
OBJECTIVE Accurate positioning of the electrode array during cochlear implant (CI) surgery is crucial for achieving optimal hearing outcomes. Traditionally, postoperative radiological imaging has been used to assess electrode position. Transimpedance matrix (TIM) measurements have also emerged as a promising method for assessing electrode position. This involves utilizing electric field imaging to create an electric distance matrix by analyzing voltage variations among adjacent electrodes. This study aimed to investigate the feasibility of using intraoperative TIM measurements to estimate electrode position and monitor postoperative changes. STUDY DESIGN Retrospective cohort study. SETTING University Medical center, tertiary academic referral center. PATIENTS Patients undergoing CI (CI622) surgery between January 2019 and June 2022. INTERVENTION CI electrode positions and maximal angular insertion depths (maxAID) were determined using X-ray imaging according to Stenvers' projection. The mean gradient phase (MGP) was extracted from the TIM, and a correlation between the MGP and maxAID was examined. A model was then built to estimate the maxAID using the MGP, and changes in electrode location over time were assessed using this model. MAIN OUTCOME MEASURES Twenty-four patients were included in this study. A positive correlation between the maxAID and the MGP ( R = 0.7, p = 0.0001) was found. The established model was able to predict the maxAID with an accuracy of 27.7 ± 4.4°. Comparing intraoperative and postoperative TIM measurements, a decrease of 24.1° ± 10.7° in maxAID over time was observed. CONCLUSION TIM measurements are useful for estimating the insertion depth of the electrode and monitoring changes in the electrode's position over time.
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Affiliation(s)
- Lichun Zhang
- Departments of Otorhinolaryngology, Head and Neck Surgery, "Otto Körner,"
| | | | - Tobias Oberhoffner
- Departments of Otorhinolaryngology, Head and Neck Surgery, "Otto Körner,"
| | - Karsten Ehrt
- Departments of Otorhinolaryngology, Head and Neck Surgery, "Otto Körner,"
| | - Daniel Cantré
- Radiology, Rostock University Medical Center, Rostock, Germany
| | - Wilma Großmann
- Departments of Otorhinolaryngology, Head and Neck Surgery, "Otto Körner,"
| | | | - Robert Mlynski
- Departments of Otorhinolaryngology, Head and Neck Surgery, "Otto Körner,"
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Warren SE, Atcherson SR. Evaluation of a clinical method for selective electrode deactivation in cochlear implant programming. Front Hum Neurosci 2023; 17:1157673. [PMID: 37063101 PMCID: PMC10101326 DOI: 10.3389/fnhum.2023.1157673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 03/09/2023] [Indexed: 03/31/2023] Open
Abstract
BackgroundCochlear implants are a neural prosthesis used to restore the perception of hearing in individuals with severe-to-profound hearing loss by stimulating the auditory nerve with electrical current through a surgically implanted electrode array. The integrity of the interface between the implanted electrode array and the auditory nerve contributes to the variability in outcomes experienced by cochlear implant users. Strategies to identify and eliminate poorly encoding electrodes have been found to be effective in improving outcomes with the device, but application is limited in a clinical setting.ObjectiveThe purpose of this study was to evaluate a clinical method used to identify and selectively deactivate cochlear implants (CI) electrodes related to poor electrode-neural interface.MethodsThirteen adult CI users participated in a pitch ranking task to identify indiscriminate electrode pairs. Electrodes associated with indiscriminate pairs were selectively deactivated, creating an individualized experimental program. Speech perception was evaluated in the baseline condition and with the experimental program before and after an acclimation period. Participant preference responses were recorded at each visit.ResultsStatistically significant improvements using the experimental program were found in at least one measure of speech perception at the individual level in four out of 13 participants when tested before acclimation. Following an acclimation period, ten out of 13 participants demonstrated statistically significant improvements in at least one measure of speech perception. Statistically significant improvements were found with the experimental program at the group level for both monosyllabic words (p = 0.006) and sentences in noise (p = 0.020). Additionally, ten participants preferred the experimental program prior to the acclimation period and eleven preferred the experimental program following the acclimation period.ConclusionResults from this study suggest that electrode deactivation may yield improvement in speech perception following an acclimation period. A majority of CI users in our study reported a preference for the experimental program. This method proved to be a suitable clinical strategy for identifying and deactivating poorly encoding electrodes in adult CI users.
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Affiliation(s)
- Sarah E. Warren
- Cochlear Implant Research Laboratory, School of Communication Sciences and Disorders, University of Memphis, Memphis, TN, United States
- Department of Audiology, Arkansas Children’s Hospital, Little Rock, AR, United States
- Department of Audiology and Speech Pathology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
- *Correspondence: Sarah E. Warren,
| | - Samuel R. Atcherson
- Department of Audiology and Speech Pathology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
- Department of Otolaryngology–Head and Neck Surgery, University of Arkansas for Medical Sciences, Little Rock, AR, United States
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Razmovski T, Bester C, Collins A, Tan E, O'Leary SJ. Four-Point Impedance Changes After Cochlear Implantation for Lateral Wall and Perimodiolar Implants. Otol Neurotol 2022; 43:e1107-e1114. [PMID: 36351225 DOI: 10.1097/mao.0000000000003732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVE Monitor four-point impedance in cochlear implant recipients over time and determine if implant type, surgical approach, and electrode positioning affected impedance measurements. STUDY DESIGN Prospective observational. SETTING Hospital. PATIENTS Adult cochlear implant recipients implanted with a perimodiolar or lateral wall cochlear implant. MAIN OUTCOME MEASURES Mean values for four-point impedances were calculated for all electrode contacts at perioperative and 3 months after surgery. Linear mixed models were applied to the impedance data to compare between implant types and time points. The angular insertion depth and electrode position relative to the medial and lateral wall, commonly termed the Intracochlear Position Index (ICPI), were collected and compared with impedance measurements. RESULTS Perioperatively, the four-point impedance was similar between implant types, with perimodiolar implants having marginally higher impedance values in the basal region. At 3 months after surgery, impedances significantly increased in the basal half of the electrode array for both implants, with higher impedance values for CI532 implants. There were no significant differences in insertion angle depth between implant types. The ICPI values for the seven most basal electrodes were similar for both implants; however, CI532 arrays were significantly more medially placed along the remaining apical portion of the array, which is expected. ICPI values did not correlate with impedance measurements for either implant. CONCLUSIONS Four-point impedance increases at 3 months after surgery may reflect fibrous tissue formation after cochlear implantation. The higher impedance values in perimodiolar implants may reflect a more extensive fibrosis formation as a result of surgical approaches used, requiring drilling of the cochlea bone.
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Affiliation(s)
- Tayla Razmovski
- Department of Surgery (Otolaryngology), The University of Melbourne
| | | | - Aaron Collins
- Department of Surgery (Otolaryngology), The University of Melbourne
| | - Eren Tan
- Department of Surgery (Otolaryngology), The University of Melbourne
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Four-point Impedance Changes in the Early Post-Operative Period After Cochlear Implantation. Otol Neurotol 2022; 43:e730-e737. [PMID: 35861642 DOI: 10.1097/mao.0000000000003592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Monitoring four-point impedance changes after cochlear implantation with comparison to conventional impedance measurements. Four-point impedance provides information regarding the bulk biological environment surrounding the electrode array, which is not discernible with conventional impedances. STUDY DESIGN Prospective observational. SETTING Hospital. PATIENTS Adult cochlear implant recipients with no measurable hearing before implantation and implanted with a perimodiolar cochlear implant. MAIN OUTCOME MEASURES Mean values for four-point and common ground impedances were calculated for all electrode contacts at intra-operative, 1 day, 1 week, 4 to 6 weeks, and 3 months post implantation. Linear mixed models were applied to the impedance data to compare between impedances and time points. Furthermore, patients were divided into groups dependent on the normalized change in four-point impedance from intra-operative to 1 day post-operative. The normalized change was then calculated for all other time points and compared across the two groups. RESULTS Significant increases in four-point impedance occurred 1 day and 3 months after surgery, particularly in the basal half of the array. Four-point impedance at 1 day was highly predictive of four-point impedance at 3 months. Four-point impedance at the other time points showed marginal or no increases from intra-operative. Patients with an average increase higher than 10% in four-point impedance from intra-operative to 1 day, had significantly higher values at 3 months ( p = 0.012). These patterns were not observed in common ground impedance. CONCLUSION This is the first study to report increases in four-point impedance within 24 hours of cochlear implantation. The increases at 1 day and 3 months align with the natural timeline of an acute and chronic inflammatory responses.
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Assessing the Placement of the Cochlear Slim Perimodiolar Electrode Array by Trans Impedance Matrix Analysis: A Temporal Bone Study. J Clin Med 2022; 11:jcm11143930. [PMID: 35887693 PMCID: PMC9317462 DOI: 10.3390/jcm11143930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 06/28/2022] [Accepted: 07/01/2022] [Indexed: 01/25/2023] Open
Abstract
New cochlear implant (CI) electrode arrays provide softer insertion dynamics; however, due to their high flexibility, the possibilities of fold-overs or intraoperative displacements must be taken into account. The position of each individual electrode can only be determined by using high-resolution computed tomography or cone-beam CT. The trans-impedance matrix test (TIM) is an electrophysiological method based on electric field imaging that can provide images of electrode position and electrode folding. Objective: In this experimental research, we evaluated the result of TIM as a method of monitoring cochlear insertion for a precurved slim modiolar electrode array in fresh human temporal bones by analyzing the transimpedance matrix patterns and their correlation with electrode position using high-resolution computed tomography. Material and Methods: Sixteen slim modiolar electrode arrays were inserted into eight fresh Human Temporal Bones. Eight electrodes were inserted according to the correct methodology of insertion, and eight were intentionally folded over. After all insertions, a trans-impedance matrix analysis and a Cone Beam CT (CBCT) were performed in each temporal bone. Results: If we correlated the TIM patterns with the radiological electrode position, we observed that better electrode intracochlear positions indicated more “homogeneous” TIM patterns (intracochlear voltage dropped monotonically as the distance between stimulation and recording contact increased, both toward the apex and toward the base). A correlation where fold-over was detected in the TIM results was found in all eight temporal bone radiological findings. Conclusions: Trans-Impedance Matrix patterns were correlated with the radiological CI electrode position. When a tip fold-over appeared, a matrix with a secondary ridge in addition to the primary ridge was observed in all cases. TIM can be an effective method in the control of electrode positioning.
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Greisiger R, Heldahl MG, Myhrum M, Sørensen TM, Dammerud JJ, Rasmussen K, Korslund H, Bunne M, Jablonski GE. Effect of Proximity to the Modiolus for the Cochlear CI532 Slim Modiolar Electrode Array on Evoked Compound Action Potentials and Programming Levels. Audiol Neurootol 2022; 27:397-405. [PMID: 35504247 DOI: 10.1159/000524256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 03/09/2022] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The first surgeries with CI532 showed an effect of the proximity of the electrode to the modiolus on the Evoked Compound Action Potentials (ECAPs). OBJECTIVES Objectives of the study were to investigate the effect of the "pullback" procedure on intraoperative ECAP responses in three different electrode array positions and additionally to compare behavioral thresholds with the thresholds obtained in a group of patients using the standard insertion. The hypothesis of this study is that pullback will cause lower ECAPs and behavioral thresholds. PATIENTS The study included 40 patients, 20 in the pullback insertion group and 20 in the standard insertion group (without pullback). METHOD During insertion of the CI532 electrode array, ECAP was performed in three different positions for the pullback group: at initial insertion, at over-insertion, and after pullback. Insertion was monitored by fluoroscopy. In the standard group, ECAP was performed at the initial position, which is also the final position. ECAP thresholds (T-ECAPs) were compared within subjects at the initial and the final position in the pullback group and between groups in the final positions of the pullback and standard groups. Programming levels (C- and T-levels) were compared between the two groups 1 year after switch-on. RESULTS Intraoperative measurements pullback shows lower average T-ECAPs after pullback compared to thresholds in initial position. Comparison of intraoperative T-ECAPs at the final positions showed no statistically significant difference between the pullback group and the standard insertion group. Furthermore, 1 year after switch-on there was no statistically significant difference in C- and T-levels between the two groups. CONCLUSION The pullback maneuver of the CI532 electrode array after an over-insertion gave significantly lower T-ECAPs compared to the thresholds at the initial position. However, the between-groups analysis of pullback and standard insertion showed neither significantly different T-ECAPs nor different programming levels. Because T-ECAPs and programming levels vary considerably between subjects, large groups are required to detect differences between groups. Additionally, the effect pullback technique to preserving the residual hearing is not known yet.
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Affiliation(s)
- Ralf Greisiger
- Department of Otorhinolaryngology, Oslo University Hospital, Oslo, Norway
| | | | - Marte Myhrum
- University of Oslo, Institute of Clinical Medicine, Oslo, Norway
| | | | | | - Kjell Rasmussen
- Department of Otorhinolaryngology, Oslo University Hospital, Oslo, Norway
| | - Hilde Korslund
- Intervention Centre, Oslo University Hospital, Oslo, Norway
| | - Marie Bunne
- Department of Otorhinolaryngology, Oslo University Hospital, Oslo, Norway
| | - Greg Eigner Jablonski
- Department of Otorhinolaryngology, Oslo University Hospital, Oslo, Norway.,University of Oslo, Institute of Clinical Medicine, Oslo, Norway
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Gao X, Grayden D, McDonnell M. Unifying information theory and machine learning in a model of electrode discrimination in cochlear implants. PLoS One 2021; 16:e0257568. [PMID: 34543336 PMCID: PMC8451994 DOI: 10.1371/journal.pone.0257568] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 09/06/2021] [Indexed: 12/02/2022] Open
Abstract
Despite the development and success of cochlear implants over several decades, wide inter-subject variability in speech perception is reported. This suggests that cochlear implant user-dependent factors limit speech perception at the individual level. Clinical studies have demonstrated the importance of the number, placement, and insertion depths of electrodes on speech recognition abilities. However, these do not account for all inter-subject variability and to what extent these factors affect speech recognition abilities has not been studied. In this paper, an information theoretic method and machine learning technique are unified in a model to investigate the extent to which key factors limit cochlear implant electrode discrimination. The framework uses a neural network classifier to predict which electrode is stimulated for a given simulated activation pattern of the auditory nerve, and mutual information is then estimated between the actual stimulated electrode and predicted ones. We also investigate how and to what extent the choices of parameters affect the performance of the model. The advantages of this framework include i) electrode discrimination ability is quantified using information theory, ii) it provides a flexible framework that may be used to investigate the key factors that limit the performance of cochlear implant users, and iii) it provides insights for future modeling studies of other types of neural prostheses.
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Affiliation(s)
- Xiao Gao
- Department of Biomedical Engineering, University of Melbourne, Parkville, VIC, Australia
- School of Physics, The University of Sydney, Sydney, NSW, Australia
- * E-mail:
| | - David Grayden
- Department of Biomedical Engineering, University of Melbourne, Parkville, VIC, Australia
| | - Mark McDonnell
- Computational Learning Systems Laboratory, School of Information Technology & Mathematical Sciences, University of South Australia, Mawson Lakes, SA, Australia
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Ramos-de-Miguel A, Falcón-González JC, Ramos-Macias A. Analysis of Neural Interface When Using Modiolar Electrode Stimulation. Radiological Evaluation, Trans-Impedance Matrix Analysis and Effect on Listening Effort in Cochlear Implantation. J Clin Med 2021; 10:jcm10173962. [PMID: 34501410 PMCID: PMC8432261 DOI: 10.3390/jcm10173962] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 08/11/2021] [Accepted: 08/31/2021] [Indexed: 11/24/2022] Open
Abstract
Background: The proximity of the electrode to the modiolar wall may be of interest to investigate the effect of pitch discrimination. This research establishes the relation between these factors and whether perimodiolar positions may provide benefits regarding improved electrode discrimination. Methods: A prospective randomized study including 24 post-lingual deaf adults was performed. A psychoacoustic study was done by using a psychoacoustic research platform. Radiological study, and a cone-beam computed tomography was used to assess post cochlear implantation electrodes’ position. Trans-impedance matrix (TIM) analysis was performed after cochlear implant insertion in all cases, and pupillometry test was also performed. Results: 12 patients received a slim perimodiolar electrode array, and 12 patients received a straight electrode array. Although all the patients showed similar speech test results after 12 months follow-up, those implanted with a perimodiolar electrode obtained better scores in electrode discrimination test and pupillometry test, and showed more homogenous TIM patterns. Conclusions: The better positioning of the electrode array seams to provide a better hearing resolution and less listening effort trans-impedance matrix seems to be a useful tool to analyze positioning of the perimodiolar array.
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Affiliation(s)
- Angel Ramos-de-Miguel
- Hearing and Balance Laboratory, Las Palmas de Gran Canaria University (SIANI), 35001 Las Palmas, Spain;
- Correspondence:
| | - Juan Carlos Falcón-González
- Department of Otolaryngology, Head and Neck Surgery, Complejo Hospitalario Universitario Insular Materno Infantil de Gran Canaria, 35016 Las Palmas, Spain;
| | - Angel Ramos-Macias
- Hearing and Balance Laboratory, Las Palmas de Gran Canaria University (SIANI), 35001 Las Palmas, Spain;
- Department of Otolaryngology, Head and Neck Surgery, Complejo Hospitalario Universitario Insular Materno Infantil de Gran Canaria, 35016 Las Palmas, Spain;
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Effects of in vivo repositioning of slim modiolar electrodes on electrical thresholds and speech perception. Sci Rep 2021; 11:15135. [PMID: 34302030 PMCID: PMC8302625 DOI: 10.1038/s41598-021-94668-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 07/13/2021] [Indexed: 02/07/2023] Open
Abstract
The slim modiolar electrode has been reported to ensure better modiolar proximity than previous conventional perimodiolar electrodes and consistently high scala tympani localization. Nonetheless, variability in modiolar proximity exists even among slim modiolar electrodes, still leaving room for further improvement of modiolar proximity, which may positively affect functional outcomes. Given this, the pull-back maneuver was reported to increase the modiolar proximity of slim modiolar electrodes in a cadaveric study, but in vivo repositioning effects remain to be established. Here we identified that the pull-back maneuver led to better modiolar proximity than conventional insertion while maintaining a similar angular insertion depth. Notably, the reduced electrode-modiolus distance from the pull-back maneuver was associated with significantly lower impedances across electrodes postoperatively as well as reduced intraoperative electrophysiological thresholds than conventional insertion. Among adult cochlear implant recipients, this maneuver resulted in significantly better sentence recognition scores at three months postoperatively when compared to those with a conventional insertion; however, this benefit was not observed at later intervals. Collectively, slim modiolar electrodes with the pull-back maneuver further enhance the modiolar proximity, possibly leading to better open-set sentence recognition, at least in the early postoperative stage.
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On the Intracochlear Location of Straight Electrode Arrays After Cochlear Implantation: How Lateral Are Lateral Wall Electrodes? Otol Neurotol 2021; 42:242-250. [PMID: 33026778 DOI: 10.1097/mao.0000000000002880] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
OBJECTIVE Cochlear implants are the gold standard for patients with severe sensorineural hearing loss. A focused electrical stimulation of individual spiral ganglion neurons has not been achieved yet because the scala tympani is a fluid-filled compartment and does not offer a matrix for neuritic outgrowth. Coating of the electrode contacts with swelling hydrogels could fill that gap between the electrode array and the medial wall of the cochlea. Therefore, the exact position of the electrode array within the scala tympani has to be known. STUDY DESIGN Retrospective analysis of patient data sets. SETTING Tertiary referral center. A total of 95 patients with cochlear implants from one manufacturer were included in this study. The lateral wall, the modiolar wall, and the cochlear implant electrode were segmented using OsiriX MD. For repositioning and reconstructing the respective contours and measuring distances, files were analyzed in MATLAB. The distances from the edge of each electrode contact to the cochlear walls showed no significant differences. But between the different contacts within each patient, there were significant differences. Around 180 degree insertion, electrodes start to get in contact with the lateral wall. The tip of the electrode array was always facing toward the modiolar wall independent of the length of the electrode. We established a method to analyze the position of electrodes within the cochlea.
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Slim, Modiolar Cochlear Implant Electrode: Melbourne Experience and Comparison With the Contour Perimodiolar Electrode. Otol Neurotol 2021; 41:639-643. [PMID: 32150026 DOI: 10.1097/mao.0000000000002617] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To describe the tip fold over rate, scalar localization, and speech perception outcomes of the CI532 Slim Modiolar Electrode. PATIENTS AND INTERVENTION All patients receiving the CI532 implant before June 2018. MAIN OUTCOME MEASURES Outcome measures for adults patients include pre- and postoperative speech perception, operative report details, electrode position as determined by X-ray and cone beam computed tomography. Comparison made with previous experience with the Contour perimodiolar electrode (CI512). In the pediatric population tip fold-over rate, measured by intraoperative X-ray, was the exclusive outcome. RESULTS One hundred twenty-five CI532 devices were implanted in adults and 69 in children. Electrode tip fold-over occurred in eight adults cases and none among children (4.1%). Cone beam CT scans of 120 out of 125 adult patients confirmed scala tympani (ST) position in all but one case where the electrode had been placed into scala vestibuli. There were no translocations from ST to scala vestibuli. This compares favorably with the CI512 translocation rate of 17%. Speech perception outcomes demonstrated good performance with mean preop phoneme scores of 16.2% (±13) increasing to 64.2% (±14) and 71.6 (±16) 3 and 12-months postop, respectively. Compared with a matched group of CI512 recipients, CI532 recipient phoneme scores were significantly higher 3 and 12-months postop by 4 and 7%, respectively. CONCLUSION The slim modiolar, CI532 electrode has provided very reliable ST position with a low rate of tip fold over. A trend toward better speech perception scores in CI532 compared with CI512 was observed.
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Simpler and effective radiological evaluations for modiolar proximity of a slim modiolar cochlear implant electrode. Sci Rep 2020; 10:17714. [PMID: 33077822 PMCID: PMC7573622 DOI: 10.1038/s41598-020-74738-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 09/22/2020] [Indexed: 01/26/2023] Open
Abstract
A new slim modiolar electrode (CI532/632) has been reported to ensure better modiolar proximity than conventional electrodes. Better modiolar proximity has been proposed to yield better electrode discrimination capability and potentially better speech outcomes, necessitating its efficient measurement. Currently, intracochlear positional index (ICPI), the most reliable indicator for evaluating modiolar proximity, has been measured exclusively through ‘metal artifact-less’ cone beam CT. However, popular use of this index is precluded due to lack of cone beam CT in many institutions. Thus, eyes are now on elucidation of easy-to-measure indicators of modiolar proximity derived from conventional CT, which is accessible in all centers. We observed that enhanced tomographic resolution significantly reduces partial volume artifacts, providing better visualization of modiolus-electrode distance. Aided by ultra-high kernel specification with high-resolution index, we developed a novel and easy-to-measure, conventional CT-specific indicator, “modified ICPI”, for evaluation of modiolar proximity. Further, we showed that it closely correlates with the previously proposed parameter of modiolar proximity, the spiral diameter, measured from post-insertion radiograph, reiterating the value of X-ray-based spiral diameter. Through this study, we have taken a step toward the stage of immediate visual feedback regarding modiolar proximity and changes in insertion technique intraoperatively, ensuring optimal modiolar proximity.
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Modiolar Proximity of Slim Modiolar Electrodes and Cochlear Duct Length: Correlation for Potential Basis of Customized Cochlear Implantation With Perimodiolar Electrodes. Ear Hear 2020; 42:323-333. [PMID: 32826506 DOI: 10.1097/aud.0000000000000920] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVES Recent studies have shown that cochlear duct length (CDL) varies among individuals and could significantly influence the final position of the electrode and its trajectory in the cochlea. Given this, we hypothesized that the degree of modiolar proximity of novel slim modiolar electrodes, such as CI532 and CI632, can also be affected by CDL. To test this hypothesis, we retrospectively evaluated individual CDL to determine if there is any significant correlation of CDL with degree of modiolar proximity. METHODS Fifty-one ears from 38 subjects implanted with slim modiolar electrodes by a single surgeon through the round window approach using the pull-back technique were included. Our cohort was classified according to the deafness onset (congenital versus postlingual) and the degree of modiolar proximity (less versus tight) with reference to the spiral diameter made by the slim modiolar electrodes in situ on transorbital x ray. We then analyzed the CDL and its metrics using a readily available surgical preplanning tool (OTOPLAN) to obtain comparable data. RESULTS Among 30 ears associated with congenital deafness, 9 ears (30%) showed less modiolar proximity, while none of the 21 ears from 19 subjects with postlingual deafness exhibited "less modiolar proximity" based on our criteria. In this study, CDL showed significant variation among subjects. Importantly, a significant inverse correlation between spiral diameter and CDL (ρ = -0.581, p < 0.001) was found, showing that shorter CDLs have longer spiral diameter and less modiolar proximity. Moreover, further pull-back technique characterized by pulling out the electrode a little bit more in cases with shorter CDL, if not always, exhibited tighter modiolar proximity. CONCLUSION A preponderance of less modiolar proximity of the electrode was observed exclusively among congenital deafness cases, demonstrated by a less tight spiral configuration even under the pull-back technique. Our data suggest that shorter CDL is associated with a less tight spiral configuration of slim modiolar electrodes postoperatively. Depending on the insertion technique, the differential degree of modiolar proximity of slim modiolar electrodes can be alleviated in cases with short CDL, which justifies cochlear duct length-based customized insertion of slim modiolar electrodes.
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Outcomes for a clinically representative cohort of hearing-impaired adults using the Nucleus® CI532 cochlear implant. Eur Arch Otorhinolaryngol 2020; 277:1625-1635. [PMID: 32140773 PMCID: PMC7198645 DOI: 10.1007/s00405-020-05893-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 02/17/2020] [Indexed: 11/03/2022]
Abstract
PURPOSE Hearing performance data was collected from a large heterogeneous group of subjects implanted with the Cochlear™ Nucleus® CI532 with Slim Modiolar Electrode, for the purposes of postmarket clinical follow-up. Data was analysed for factors which may predict postoperative speech recognition scores. METHODS Data was collected retrospectively from five German clinics for 159 subjects from March 2017 to August 2018. Hearing thresholds and recognition scores for monosyllabic words in quiet and sentences in noise were measured preoperatively and at 3 and 6 months postoperatively. RESULTS There was a mean gain of 44% points (95% CI 39-49%) at 6 months in monosyllable scores in quiet for implanted ears. Preoperative hearing thresholds in implant ears increased systematically with decreasing age; however, younger subjects had better baseline monosyllable scores with hearing aids compared with older subjects. Baseline performance alone explained 14% of the variation in postoperative scores. Residual hearing was preserved on average to within 22 dB at 250 Hz and 30 dB at 500 Hz of preoperative levels. CONCLUSIONS In a large and varied cohort of routinely treated hearing-impaired adults, speech recognition with the CI532 for German monosyllabic words in quiet at 6 months was equivalent to performance reported at one year or more in other published studies. Although younger subjects had poorer preoperative pure-tone thresholds, they had better preoperative word recognition scores compared with older subjects, and also had higher post implant scores. Further research is required to identify if this phenomenon is just applicable to German health system assessment and referral practices.
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Videhult Pierre P, Eklöf M, Smeds H, Asp F. Cochlear Implantation with the CI512 and CI532 Precurved Electrode Arrays: One-Year Speech Recognition and Intraoperative Thresholds of Electrically Evoked Compound Action Potentials. Audiol Neurootol 2019; 24:299-308. [PMID: 31846976 DOI: 10.1159/000504592] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 11/05/2019] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION Precurved cochlear implant (CI) electrode arrays were developed in an attempt to improve the auditory outcome of cochlear implantation, which varies greatly. The recent CI532 (Cochlear Corp., Sydney, Australia) may offer further advantages as its electrode array is thinner than previous precurved CI electrode arrays. The aims here were to investigate 1-year postoperative speech recognition, intraoperative electrically evoked compound action potentials (ECAPs), and their possible relation in patients implanted with a CI532 or its predecessor CI512. METHODS A retrospective analysis of data from 63 patients subjected to cochlear implantation at the Karolinska University Hospital, Sweden, was performed. Speech recognition of the implanted ear was evaluated using phonemically balanced monosyllabic Swedish words at 65 dB SPL. ECAPs were evaluated using the intraoperative ECAP threshold across ≥8 electrodes generated by the automated neural response telemetry of the CI. RESULTS The median aided speech recognition score (SRS) 1 year after implantation was 52% (quartile 1 = 40%, quartile 3 = 60%, n = 63) and did not differ statistically significantly between patients with CI512 (n = 38) and CI532 (n = 25). The mean ECAP threshold was 188 CL (current level; SD = 15 CL, n = 54) intraoperatively and did not differ statistically significantly between patients with CI512 (n = 32) and CI532 (n = 22), but the threshold for each electrode varied more between patients with a CI512 (p < 0.0001). A higher mean ECAP threshold was associated with a worse SRS (Spearman's ρ = -0.46, p = 0.0004, n = 54). The association remained among those with a CI512 (Spearman's ρ = -0.62, p = 0.0001, n = 32) when stratified by CI electrode array. CONCLUSION No statistically significant difference in speech recognition 1 year after cochlear implantation or in mean threshold of ECAP intraoperatively was found between patients with a CI512 and the more recent, slim CI532, but the ECAP thresholds varied more between those with a CI512. A statistically significant association between SRS and mean ECAP threshold was found, but stratified analysis suggests that the association may be true only for patients with a CI512.
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Affiliation(s)
- Pernilla Videhult Pierre
- Division of Audiology, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden,
| | - Martin Eklöf
- Division of Ear, Nose and Throat, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden.,Department of Otorhinolaryngology, Karolinska University Hospital, Stockholm, Sweden
| | - Henrik Smeds
- Division of Ear, Nose and Throat, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden.,Department of Otorhinolaryngology, Karolinska University Hospital, Stockholm, Sweden
| | - Filip Asp
- Division of Ear, Nose and Throat, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden.,Department of Otorhinolaryngology, Karolinska University Hospital, Stockholm, Sweden
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Lee JY, Hong SH, Moon IJ, Kim EY, Baek E, Seol HY, Kang S. Effect of Cochlear Implant Electrode Array Design on Electrophysiological and Psychophysical Measures: Lateral Wall versus Perimodiolar Types. J Audiol Otol 2019; 23:145-152. [PMID: 31315391 PMCID: PMC6646897 DOI: 10.7874/jao.2019.00164] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 06/04/2019] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND AND OBJECTIVES The present study aims to investigate whether the cochlear implant electrode array design affects the electrophysiological and psychophysical measures. SUBJECTS AND METHODS Eighty five ears were used as data in this retrospective study. They were divided into two groups by the electrode array design: lateral wall type (LW) and perimodiolar type (PM). The electrode site was divided into three regions (basal, medial, apical). The evoked compound action potential (ECAP) threshold, T level, C level, dynamic range (DR), and aided air conduction threshold were measured. RESULTS The ECAP threshold was lower for the PM than for the LW, and decreased as the electrode site was closer to the apical region. The T level was lower for the PM than for the LW, and was lower on the apical region than on the other regions. The C level on the basal region was lower for the PM than for the LW whereas the C level was lower on the apical region than on the other regions. The DRs on the apical region was greater for the PM than for the LW whereas the DR was narrower on the apical region than on the other regions. The aided air conduction threshold was not different for the electrode design and frequency. CONCLUSIONS The current study would support the advantages of the PM over the LW in that the PM had the lower current level and greater DR, which could result in more localized neural stimulation and reduced power consumption.
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Affiliation(s)
- Ji Young Lee
- Department of Audiology and Speech-Language Pathology, Daegu Catholic University, Gyeongsan, Korea
| | - Sung Hwa Hong
- Department of Otorhinolaryngology-Head and Neck-Surgery, Samsung Changwon Hospital, School of Medicine, Sungkyunkwan University, Changwon, Korea
| | - Il Joon Moon
- Department of Otorhinolaryngology-Head and Neck-Surgery, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, Korea.,Hearing Research Laboratory of Samsung Medical Center-Samsung Electronics Co., Seoul, Korea
| | - Eun Yeon Kim
- Department of Speech-Language Pathology, Graduate School of Social Education, Myongji University, Seoul, Korea
| | - Eunjoo Baek
- Department of Otorhinolaryngology-Head and Neck-Surgery, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, Korea
| | - Hye Yoon Seol
- Hearing Research Laboratory of Samsung Medical Center-Samsung Electronics Co., Seoul, Korea.,Sungkyunkwan University Samsung Advanced Institute for Health Sciences and Technology, Seoul, Korea
| | - Sihyung Kang
- Department of Otorhinolaryngology-Head and Neck-Surgery, Samsung Changwon Hospital, School of Medicine, Sungkyunkwan University, Changwon, Korea
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Evaluation of Intracochlear Position of a Slim Modiolar Electrode Array, by Using Different Radiological Analyses. Otol Neurotol 2019; 40:S10-S17. [PMID: 31225817 DOI: 10.1097/mao.0000000000002213] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
INTRODUCTION The radiological analysis following a cochlear implantation offers insight into the audiological outcomes of cochlear implant recipients. The wrapping factor (WF) is the most common radiological analysis measuring the modiolar position and depth of insertion of an electrode array. New measurements like the intracochlear position index (ICPI) or the homogeneity factor (HF) can offer more accurate information regarding the electrode's intracochlear position. We have also studied a new method to calculate the WF, by normalizing it with a new methodology (WFn). OBJECTIVES To analyze and compare the results of the WF, ICPI, HF, and WFn obtained using a cone beam computer tomography (CBCT) with the histological analysis on temporal bone. MATERIAL A perimodiolar electrode array (Nucleus Slim CI532) was inserted in three temporal bones. A perfect insertion was performed in the first temporal bone, according to the correct specifications. In the second specimen, a slightly over-inserted electrode was analyzed and in the third specimen a completely over-inserted electrode array was studied. METHOD A CBCT was performed following the implantations and then, a histological analysis with slices perpendicular to the cochlea axis (modiolus). Each measurement was made 10 times by 10 experts (radiologist and otologist) with a total amount of 600 measurements (100 for each data, 3 CBCT and 3 histology). A t test statistical analysis was performed to compare the measurements between CBCT and histology. RESULTS It was observed that the ICPI and the HF correctly identify the three different insertions. Regarding the WF no significant difference in the two over-inserted specimens was found. The ICPI was the only measurement that shows no statistical difference between the CBCT and the histology, so it was considered the most accurate method. Finally, the WF shows a statistical difference between the CBCT and the histology in all cases, indicating the poor value of the radiological method. The WFn analysis includes the modiolar wall length in the measurement. This improves the final result as it reduces the error induced by the size of the cochlea. CONCLUSION The ICPI and the HF provide better radiological information than the WF, regarding the intracochlear position of the electrode array. The most relevant difference is that the ICPI, HF, and WFn include modiolar and lateral wall dimensions, thereby using the diameter of the cochlear duct for the analysis.
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Biesheuvel JD, Briaire JJ, de Jong MAM, Boehringer S, Frijns JHM. Channel discrimination along all contacts of the cochlear implant electrode array and its relation to speech perception. Int J Audiol 2019; 58:262-268. [PMID: 30890005 DOI: 10.1080/14992027.2019.1573384] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVE To test the channel discrimination of cochlear implant (CI) users along all contacts of the electrode array and assess whether this is related to speech perception. DESIGN CI recipients were tested with a custom-made channel discrimination test. They were asked to distinguish a target stimulus from two reference stimuli in a three-alternative forced choice (3AFC) task. The target stimulus was evoked using current steering, with current steering coefficients (α) of 1, 0.5 and 0.25. The test provided a discrimination score (Dα) for each electrode contact along the array. STUDY SAMPLE Thirty adults implanted with a CI from Advanced Bionics. RESULTS Large variations in Dα scores were observed, both across the electrode array and between subjects. Statistical analysis revealed a significant channel-to-channel variability in Dα score (p < 0.01). Further, there was a significant relationship between subjects' Dα scores and their speech perception in quiet (p < 0.001). CONCLUSIONS The large variations in Dα score emphasise the importance of testing pitch discrimination across the complete electrode array. The relationship between Dα score and speech perception indicates that pitch discrimination might be a contributing factor to the performance of individual implant users.
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Affiliation(s)
- Jan Dirk Biesheuvel
- a ENT Department , Leiden University Medical Centre , Leiden , The Netherlands
| | - Jeroen J Briaire
- a ENT Department , Leiden University Medical Centre , Leiden , The Netherlands
| | - Monique A M de Jong
- a ENT Department , Leiden University Medical Centre , Leiden , The Netherlands
| | - Stefan Boehringer
- b Department of Biomedical Data Sciences , Leiden University Medical Centre , Leiden , The Netherlands
| | - Johan H M Frijns
- a ENT Department , Leiden University Medical Centre , Leiden , The Netherlands.,c Leiden Institute for Brain and Cognition , Leiden , The Netherlands
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Risi F. Considerations and Rationale for Cochlear Implant Electrode Design - Past, Present and Future. J Int Adv Otol 2018; 14:382-391. [PMID: 30644379 PMCID: PMC6354527 DOI: 10.5152/iao.2018.6372] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 12/17/2018] [Indexed: 12/16/2022] Open
Abstract
The electrode array of a cochlear implant forms a permanent, often lifelong interface between the implanted electronics and neural structures of the cochlea. A cochlear implant is primarily prescribed to restore hearing via electrical stimulation of the auditory nerve. As with any neural stimulator intended to either deliver electrical stimulus or record a neural response, the aim is to place the electrodes in close proximity to the target neural structures. The broadening of indications and the concept of preservation of low-frequency residual hearing over the last two decades has resulted in an increased understanding of the mechanisms and implications of intracochlear trauma for both the hearing preservation surgery and electrical stimulation outcomes with cochlear implantation, as well as the influence of many biographic and audiological patient factors correlated with achieving better hearing outcomes. These two goals, the proximity to the cochlear nerve for electrical stimulation and the preservation of cochlear structures, have typically been viewed as mutually exclusive, with perimodiolar electrode arrays being preferred for the former, and lateral wall electrode arrays for the latter. The design evolution of both the lateral wall and perimodiolar electrodes is presented, considering the cochlea anatomy and continued understanding of the mechanics and dynamics of electrode insertion, along with the influence of the ongoing changes to the intracochlear environment to provide a rationale for the electrode design with the intent to provide the greatest patient benefit over their implanted lifetime.
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Affiliation(s)
- Frank Risi
- Group Product Manager, Surgical - Implants, Cochlear Limited, New South Wales, Australia
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