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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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Mewes A, Dambon J, Brademann G, Hey M. Curvature analysis of CI electrode arrays: a novel approach to categorize perimodiolar positions without anatomical landmarks. Eur Arch Otorhinolaryngol 2024:10.1007/s00405-024-08917-1. [PMID: 39214908 DOI: 10.1007/s00405-024-08917-1] [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: 06/24/2024] [Accepted: 08/12/2024] [Indexed: 09/04/2024]
Abstract
PURPOSE Perimodiolar electrode arrays may be positioned regular, over-inserted or under-inserted into the cochlea depending on the cochlear size and shape. The study aimed to examine whether there are differences between these groups in the local curvature along the intracochlear array. Individual curvature variables were developed to categorize the groups and the relationship between the curvature and the angular insertion depth at the electrode tip was analyzed. METHODS The curvature along the intracochlear array was measured in the CBCT image of 85 perimodiolar electrodes of a single type. The mean curvature and the ratio of the mean curvature at contacts E14-16 to the mean curvature at E7-8 (bowing ratio) were calculated across the array, and its true positive rate (TPR) and false positive rate (FPR) were calculated to establish optimal threshold values to categorize the groups. RESULTS 68.2% of the cases were categorized as regular positioned, 22.4% had an over-insertion and 9.4% had an under-insertion. The mean curvature was significantly weaker with under-insertion (< 342°) than with normal insertion depth (≥ 342°). With an over-insertion, the bowing ratio was < 1 and otherwise > 1. Both the mean curvature and bowing ratio were found to have an optimal threshold value with high TPR (= 1.00) and low FPR (≤ 0.06) for categorizing under-insertion and over-insertion, respectively. CONCLUSION Curvature analysis is a useful tool to assess if a perimodiolar electrode array has been inserted deep enough into the cochlea. Independent of critical anatomical landmarks, over-inserted arrays and under-inserted arrays could be well categorized by using individual curvature variables. The results need to be validated using additional data sets.
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Affiliation(s)
- Alexander Mewes
- Christian-Albrecht University of Kiel, Kiel, Germany.
- Department of Otorhinolaryngology, Head and Neck Surgery, Universitätsklinikum Schleswig-Holstein (UKSH), Campus Kiel, Kiel, Germany.
| | - Jan Dambon
- Department of Otorhinolaryngology, Head and Neck Surgery, Universitätsklinikum Schleswig-Holstein (UKSH), Campus Kiel, Kiel, Germany
| | - Goetz Brademann
- Department of Otorhinolaryngology, Head and Neck Surgery, Universitätsklinikum Schleswig-Holstein (UKSH), Campus Kiel, Kiel, Germany
| | - Matthias Hey
- Department of Otorhinolaryngology, Head and Neck Surgery, Universitätsklinikum Schleswig-Holstein (UKSH), Campus Kiel, Kiel, Germany
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Koyama H, Kashio A, Yamasoba T. Prediction of Cochlear Implant Fitting by Machine Learning Techniques. Otol Neurotol 2024; 45:643-650. [PMID: 38769101 DOI: 10.1097/mao.0000000000004205] [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: 05/22/2024]
Abstract
OBJECTIVE This study aimed to evaluate the differences in electrically evoked compound action potential (ECAP) thresholds and postoperative mapping current (T) levels between electrode types after cochlear implantation, the correlation between ECAP thresholds and T levels, and the performance of machine learning techniques in predicting postoperative T levels. STUDY DESIGN Retrospective case review. SETTING Tertiary hospital. PATIENTS We reviewed the charts of 124 ears of children with severe-to-profound hearing loss who had undergone cochlear implantation. INTERVENTIONS We compared ECAP thresholds and T levels from different electrodes, calculated correlations between ECAP thresholds and T levels, and created five prediction models of T levels at switch-on and 6 months after surgery. MAIN OUTCOME MEASURES The accuracy of prediction in postoperative mapping current (T) levels. RESULTS The ECAP thresholds of the slim modiolar electrodes were significantly lower than those of the straight electrodes on the apical side. However, there was no significant difference in the neural response telemetry thresholds between the two electrodes on the basal side. Lasso regression achieved the most accurate prediction of T levels at switch-on, and the random forest algorithm achieved the most accurate prediction of T levels 6 months after surgery in this dataset. CONCLUSION Machine learning techniques could be useful for accurately predicting postoperative T levels after cochlear implantation in children.
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Affiliation(s)
- Hajime Koyama
- Department of Otorhinolaryngology and Head and Neck Surgery, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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Gerbert M, Ernst A, Seidl R, Decker L, Scholz S, Lauer G, Mittmann P. Preservation of Residual Hearing: Long-Term Results With a Mid-Scala Electrode. J Otolaryngol Head Neck Surg 2024; 53:19160216241250351. [PMID: 38888946 PMCID: PMC11155315 DOI: 10.1177/19160216241250351] [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: 02/29/2024] [Accepted: 03/30/2024] [Indexed: 06/20/2024] Open
Abstract
OBJECTIVE The long-term preservation of residual hearing after cochlear implantation has become a major goal over the past few years. The aim of the present study was to evaluate residual hearing in the long-term follow-up using mid-scala electrodes. METHODS In this retrospective, single-center study, we collected data from 27 patients who were implanted between 2014 and 2015 with residual hearing in the low-frequency range using a mid-scala electrode. Measurements of the hearing thresholds were carried out directly postoperatively (day 1 after surgery) and in the long-term follow-up 43.7 ± 6.9 months. The calculation of the extent of audiological hearing preservation was determined using the HEARRING group formula by Skarsynski. RESULTS Postoperative preservation of residual hearing was achieved in 69.2% of the cases in the low-frequency range between 250 Hz and 1 kHz, of which 89.5% of the patients had frequencies that suggested using electroacoustic stimulation (EAS). In the long-term follow-up, 30.8% of the patients showed residual hearing; however, 57.1% had apparently benefited from EAS. CONCLUSION Preservation of residual hearing is feasible in the long term using mid-scala electrodes. Postoperatively, there is over the half of patients who benefit from an EAS strategy. The long-term follow-up shows a certain decrease in residual hearing. However, these results are comparable to studies relating to other types of electrodes. Further research should be conducted in future to better evaluate hearing loss in long-term follow-up, compared to direct postoperative audiological results.
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Affiliation(s)
- Martin Gerbert
- Department of Otolaryngology, Head and Neck Surgery, Unfallkrankenhaus Berlin, Berlin, Germany
| | - Arne Ernst
- Department of Otolaryngology, Head and Neck Surgery, Unfallkrankenhaus Berlin, Berlin, Germany
| | - Rainer Seidl
- Department of Otolaryngology, Head and Neck Surgery, Unfallkrankenhaus Berlin, Berlin, Germany
| | - Lars Decker
- Department of Otolaryngology, Head and Neck Surgery, Unfallkrankenhaus Berlin, Berlin, Germany
| | - Sandra Scholz
- Department of Otolaryngology, Head and Neck Surgery, Unfallkrankenhaus Berlin, Berlin, Germany
| | - Gina Lauer
- Department of Otolaryngology, Head and Neck Surgery, Unfallkrankenhaus Berlin, Berlin, Germany
| | - Philipp Mittmann
- Department of Otolaryngology, Head and Neck Surgery, Unfallkrankenhaus Berlin, Berlin, Germany
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Mussoi BS, Meibos A, Woodson E, Sydlowski S. The association between electrode impedance and short-term outcomes in cochlear implant recipients of slim modiolar and slim straight electrode arrays. Cochlear Implants Int 2024; 25:59-68. [PMID: 38081181 DOI: 10.1080/14670100.2023.2290768] [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] [Indexed: 07/17/2024]
Abstract
OBJECTIVES Electrode impedance measurements from cochlear implants (CI) reflect the status of the electrode array as well as the surrounding cochlear environment, and could provide a clinical index of functional changes with the CI. The goals of this study were to examine (1) the impact of electrode array type on electrode impedance, and (2) the relationship between electrode impedance and short-term hearing preservation and speech recognition outcomes. METHODS Retrospective study of 115 adult hearing preservation CI recipients of a slim modiolar or slim straight array. Common ground electrode impedances, pre- and post-operative hearing thresholds and CNC word recognition scores were retrieved. RESULTS Electrode impedances were significantly higher for recipients of the straight electrode array. Within individuals, electrode impedances were stable after the first week post-activation. However, increased standard deviation of electrode impedances was associated with greater loss of low frequency hearing at initial activation, and with poorer speech recognition at 6 months post-implantation. CONCLUSIONS Results demonstrate that electrode impedances depend on the type of implanted array. Findings also suggest that there may be a role for the variability in electrode impedance across electrodes as an indicator of changes in the intracochlear environment that contribute to outcomes with a CI.
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Affiliation(s)
- Bruna S Mussoi
- Speech Pathology and Audiology, Kent State University, Kent, OH, USA
| | - Alex Meibos
- School of Speech-Language Pathology and Audiology, The University of Akron, Akron, OH, USA
| | - Erika Woodson
- Head and Neck Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Sarah Sydlowski
- Head and Neck Institute, Cleveland Clinic, Cleveland, OH, USA
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Khurana L, Harczos T, Moser T, Jablonski L. En route to sound coding strategies for optical cochlear implants. iScience 2023; 26:107725. [PMID: 37720089 PMCID: PMC10502376 DOI: 10.1016/j.isci.2023.107725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/19/2023] Open
Abstract
Hearing loss is the most common human sensory deficit. Severe-to-complete sensorineural hearing loss is often treated by electrical cochlear implants (eCIs) bypassing dysfunctional or lost hair cells by direct stimulation of the auditory nerve. The wide current spread from each intracochlear electrode array contact activates large sets of tonotopically organized neurons limiting spectral selectivity of sound coding. Despite many efforts, an increase in the number of independent eCI stimulation channels seems impossible to achieve. Light, which can be better confined in space than electric current may help optical cochlear implants (oCIs) to overcome eCI shortcomings. In this review, we present the current state of the optogenetic sound encoding. We highlight optical sound coding strategy development capitalizing on the optical stimulation that requires fine-grained, fast, and power-efficient real-time sound processing controlling dozens of microscale optical emitters as an emerging research area.
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Affiliation(s)
- Lakshay Khurana
- Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany
- Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany
- Auditory Neuroscience and Synaptic Nanophysiology Group, Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany
- Junior Research Group “Computational Neuroscience and Neuroengineering”, Göttingen, Germany
- The Doctoral Program “Sensory and Motor Neuroscience”, Göttingen Graduate Center for Neurosciences, Biophysics, and Molecular Biosciences (GGNB), Göttingen, Germany
- InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Tamas Harczos
- Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany
- Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany
- Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany
- Auditory Neuroscience and Synaptic Nanophysiology Group, Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany
- InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC), University of Göttingen, Göttingen, Germany
| | - Lukasz Jablonski
- Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany
- Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany
- Junior Research Group “Computational Neuroscience and Neuroengineering”, Göttingen, Germany
- InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
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Smetak MR, Riojas KE, Whittenbarger N, Noble JH, Labadie RF. Dynamic Behavior and Insertional Forces of a Precurved Electrode Using the Pull-Back Technique in a Fresh Microdissected Cochlea. Otol Neurotol 2023; 44:324-330. [PMID: 36728107 PMCID: PMC10038836 DOI: 10.1097/mao.0000000000003812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
HYPOTHESIS This study evaluated the utility of the pull-back technique in improving perimodiolar positioning of a precurved cochlear implant (CI) electrode array (EA) with simultaneous insertion force profile measurement and direct observation of dynamic EA behavior. BACKGROUND Precurved EAs with perimodiolar positioning have improved outcomes compared with straight EAs because of lowered charge requirements for stimulation and decreased spread of excitation. The safety and efficacy of the pull-back technique in further improving perimodiolar positioning and its associated force profile have not been adequately demonstrated. METHODS The bone overlying the scala vestibuli was removed in 15 fresh cadaveric temporal bones, leaving the scala tympani unviolated. Robotic insertions of EAs were performed with simultaneous force measurement and video recording. Force profiles were obtained during standard insertion, overinsertion, and pull-back. Postinsertion CT scans were obtained during each of the three conditions, enabling automatic segmentation and calculation of angular insertion depth, mean perimodiolar distance ( Mavg ), and cochlear duct length. RESULTS Overinsertion did not result in significantly higher peak forces than standard insertion (mean [SD], 0.18 [0.06] and 0.14 [0.08] N; p = 0.18). Six temporal bones (40%) demonstrated visibly improved perimodiolar positioning after the protocol, whereas none worsened. Mavg significantly improved after the pull-back technique compared with standard insertion (mean [SD], 0.34 [0.07] and 0.41 [0.10] mm; p < 0.01). CONCLUSIONS The pull-back technique was not associated with significantly higher insertional forces compared with standard insertion. This technique was associated with significant improvement in perimodiolar positioning, both visually and quantitatively, independent of cochlear size.
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Affiliation(s)
- Miriam R. Smetak
- Department of Otolaryngology – Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN
| | | | - Noah Whittenbarger
- Department of Otolaryngology – Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN
| | - Jack H. Noble
- Department of Electrical Engineering & Computer Science, Vanderbilt University, Nashville, TN
| | - Robert F. Labadie
- Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, Charleston, SC
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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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Khurana L, Keppeler D, Jablonski L, Moser T. Model-based prediction of optogenetic sound encoding in the human cochlea by future optical cochlear implants. Comput Struct Biotechnol J 2022; 20:3621-3629. [PMID: 35860414 PMCID: PMC9283772 DOI: 10.1016/j.csbj.2022.06.061] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/28/2022] [Accepted: 06/28/2022] [Indexed: 01/17/2023] Open
Abstract
When hearing fails, electrical cochlear implants (eCIs) partially restore hearing by direct stimulation of spiral ganglion neurons (SGNs). As light can be better confined in space than electrical current, optical CIs (oCIs) provide more spectral information promising a fundamental improvement of hearing restoration by cochlear implants. Here, we turned to computer modelling for predicting the outcome of optogenetic hearing restoration by future oCIs in humans. We combined three-dimensional reconstruction of the human cochlea with ray-tracing simulation of emission from LED or laser-coupled waveguide emitters of the oCI. Irradiance was read out at the somata of SGNs. The irradiance values reached with waveguides were about 14 times higher than with LEDs, at the same radiant flux of the emitter. Moreover, waveguides outperformed LEDs regarding spectral selectivity. oCIs with either emitter type showed greater spectral selectivity when compared to eCI. In addition, modeling the effects of the source-to-SGN distance, orientation of the sources and impact of scar tissue further informs the development of optogenetic hearing restoration.
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Affiliation(s)
- Lakshay Khurana
- Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany
- Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany
- Auditory Neuroscience & Synaptic Nanophysiology Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Göttingen Graduate Center for Neurosciences, Biophysics, and Molecular Biosciences (GGNB), University of Göttingen, Göttingen, Germany
- InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Daniel Keppeler
- Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany
- Auditory Neuroscience & Synaptic Nanophysiology Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Lukasz Jablonski
- Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany
- Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany
- InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany
- Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany
- Auditory Neuroscience & Synaptic Nanophysiology Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC), University of Göttingen, Göttingen, Germany
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Variations in microanatomy of the human modiolus require individualized cochlear implantation. Sci Rep 2022; 12:5047. [PMID: 35322066 PMCID: PMC8943032 DOI: 10.1038/s41598-022-08731-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 03/10/2022] [Indexed: 11/09/2022] Open
Abstract
Cochlear variability is of key importance for the clinical use of cochlear implants, the most successful neuroprosthetic device that is surgically placed into the cochlear scala tympani. Despite extensive literature on human cochlear variability, few information is available on the variability of the modiolar wall. In the present study, we analyzed 108 corrosion casts, 95 clinical cone beam computer tomographies (CTs) and 15 µCTs of human cochleae and observed modiolar variability of similar and larger extent than the lateral wall variability. Lateral wall measures correlated with modiolar wall measures significantly. ~ 49% of the variability had a common cause. Based on these data we developed a model of the modiolar wall variations and related the model to the design of cochlear implants aimed for perimodiolar locations. The data demonstrate that both the insertion limits relevant for lateral wall damage (approximate range of 4–9 mm) as well as the dimensions required for optimal perimodiolar placement of the electrode (the point of release from the straightener; approximate range of 2–5mm) are highly interindividually variable. The data demonstrate that tip fold-overs of preformed implants likely result from the morphology of the modiolus (with radius changing from base to apex), and that optimal cochlear implantation of perimodiolar arrays cannot be guaranteed without an individualized surgical technique.
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Biesheuvel JD, Briaire JJ, Kalkman RK, Frijns JH. The effect of stimulus level on excitation patterns of individual electrode contacts in cochlear implants. Hear Res 2022; 420:108490. [DOI: 10.1016/j.heares.2022.108490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 03/18/2022] [Accepted: 03/23/2022] [Indexed: 11/26/2022]
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Sijgers L, Huber A, Tabibi S, Grosse J, Roosli C, Boyle P, Koka K, Dillier N, Pfiffner F, Dalbert A. Predicting Cochlear Implant Electrode Placement Using Monopolar, Three-Point and Four-Point Impedance Measurements. IEEE Trans Biomed Eng 2022; 69:2533-2544. [PMID: 35143392 DOI: 10.1109/tbme.2022.3150239] [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: 11/06/2022]
Abstract
OBJECTIVE This study aimed to investigate the relationship between cochlear implant (CI) electrode distances to the cochleas inner wall (the modiolus) and electrical impedance measurements made at the CIs electrode contacts. We introduced a protocol for three-point impedances in which we recorded bipolar impedances in response to monopolar stimulation at a neighboring electrode. We aimed to assess the usability of three-point impedances and two existing CI impedance measurement methods (monopolar and four-point impedances) for predicting electrode positioning during CI insertion. METHODS Impedances were recorded during stepwise CI electrode array insertions in cadaveric human temporal bones. The positioning of the electrodes with respect to the modiolus was assessed at each step using cone beam computed tomography. Linear mixed regression analysis was performed to assess the relationship between the impedances and electrode-modiolar distances. The experimental results were compared to clinical impedance data and to an existing lumped-element model of an implanted CI. RESULTS Three-point and four-point impedances strongly correlated with electrode-modiolar distance. In contrast, monopolar impedances were only minimally affected by changes in electrode positioning with respect to the modiolus. An overall model specificity of 62% was achieved when incorporating all impedance parameters. This specificity could be increased beyond 73% when prior expectations of electrode positioning were incorporated in the model. CONCLUSION Three-point and four-point impedances are promising measures to predict electrode-modiolar distance in real-time during CI insertion. SIGNIFICANCE This work shows how electrical impedance measurements can be used to predict the CIs electrode positioning in a biologically realistic model.
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Intracochlear New Fibro-Ossification and Neuronal Degeneration Following Cochlear Implant Electrode Translocation: Long-Term Histopathological Findings in Humans. Otol Neurotol 2022; 43:e153-e164. [PMID: 35015749 DOI: 10.1097/mao.0000000000003402] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
OBJECTIVE We aim to assess the histopathology of human temporal bones (TBs) with evidence of cochlear implantation (CI) electrode scalar translocation. STUDY DESIGN Otopathology study. SETTING Otopathology laboratory. PATIENTS TBs from patients who had a history of CI and histopathological evidence of interscalar translocation. Specimens with electrode placed entirely within the ST served as controls. INTERVENTION Histopathological assessment of human TBs. MAIN OUTCOME MEASURES TBs from each patient were harvested postmortem and histologically analyzed for intracochlear changes in the context of CI electrode translocation and compared to controls. Intracochlear new fibro-ossification, and spiral ganglion neuron (SGN) counts were assessed. Postoperative word recognition scores (WRS) were also compared. RESULTS Nineteen human TBs with electrode translocation and eight controls were identified. The most common site of translocation was the ascending limb of the basal turn (n = 14 TBs). The average angle of insertion at the point of translocation was 159° ± 79°. Eighteen translocated cases presented moderate fibroosseous changes in the basal region of the cochlea, extending to the translocation point and/or throughout the electrode track in 42%. Lower SGN counts were more pronounced in translocated cases compared to controls, with a significant difference for segment II (p = 0.019). Although final postoperative hearing outcomes were similar between groups, translocated cases had slower rate of improvement in WRS (p = 0.021). CONCLUSIONS Cochlear implant electrode translocation was associated with greater fibroosseous formation and lower SGN population. Our findings suggest that scalar translocations may slow the rate of improvement in WRS overtime as compared to atraumatic electrode insertions.Level of evidence: IV.
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Intracochlear electrode array position and cochlear implant outcomes using the nucleus slim modiolar electrode and the extended round window approach: a follow-up study. Eur Arch Otorhinolaryngol 2022; 279:4735-4743. [PMID: 35041067 PMCID: PMC9474433 DOI: 10.1007/s00405-021-07247-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 12/28/2021] [Indexed: 01/10/2023]
Abstract
PURPOSE The aim of this study was to evaluate the intracochlear position of the Slim Modiolar Electrode (SME) after insertion via the extended Round Window (eRW) approach, and to correlate this with residual hearing preservation and speech perception outcomes. METHODS Twenty-three adult participants, consecutively implanted with the SME via the eRW approach, were included in this prospective, single-center, observational study. Electrode position was evaluated intra-operatively using X-ray fluoroscopy and TIM measurement, and post-operatively using ultra-high resolution CT. Residual hearing [threshold shift in PTA between pre- and post-operative measurement, relative hearing preservation (RHP%)] and speech perception were evaluated at 2 and 12 months after surgery. RESULTS In each of the 23 participants, complete scala tympani positioning of the electrode array could be achieved. In one participant, an initial tip fold-over was corrected during surgery. Average age at implantation was 63.3 years (SD 13.3, range 28-76) and mean preoperative residual hearing was 81.5 dB. The average post-operative PTA threshold shift was 16.2 dB (SD 10.8) at 2 months post-operatively, corresponding with a RHP% score of 44% (SD 34.9). At 12 months, the average RHP% score decreased to 37%. Postoperative phoneme scores improved from 27.1% preoperatively, to 72.1% and 82.1% at 2 and 12 months after surgery, respectively. CONCLUSION Use of the eRW approach results in an increased likelihood of complete scala tympani insertion when inserting the SME, with subsequent excellent levels of speech perception. However, residual hearing preservation was found to be moderate, possibly as a result of the extended round window approach, emphasizing that it is not an all-purpose approach for inserting this particular electrode array.
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MacPhail ME, Connell NT, Totten DJ, Gray MT, Pisoni D, Yates CW, Nelson RF. Speech Recognition Outcomes in Adults With Slim Straight and Slim Modiolar Cochlear Implant Electrode Arrays. Otolaryngol Head Neck Surg 2021; 166:943-950. [PMID: 34399646 DOI: 10.1177/01945998211036339] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To compare differences in audiologic outcomes between slim modiolar electrode (SME) CI532 and slim lateral wall electrode (SLW) CI522 cochlear implant recipients. STUDY DESIGN Retrospective cohort study. SETTING Tertiary academic hospital. METHODS Comparison of postoperative AzBio sentence scores in quiet (percentage correct) in adult cochlear implant recipients with SME or SLW matched for preoperative AzBio sentence scores in quiet and aided and unaided pure tone average. RESULTS Patients with SLW (n = 52) and patients with SME (n = 37) had a similar mean (SD) age (62.0 [18.2] vs 62.6 [14.6] years, respectively), mean preoperative aided pure tone average (55.9 [20.4] vs 58.1 [16.4] dB; P = .59), and mean AzBio score (percentage correct, 11.1% [13.3%] vs 8.0% [11.5%]; P = .25). At last follow-up (SLW vs SME, 9.0 [2.9] vs 9.9 [2.6] months), postoperative mean AzBio scores in quiet were not significantly different (percentage correct, 70.8% [21.3%] vs 65.6% [24.5%]; P = .29), and data log usage was similar (12.9 [4.0] vs 11.3 [4.1] hours; P = .07). In patients with preoperative AzBio <10% correct, the 6-month mean AzBio scores were significantly better with SLW than SME (percentage correct, 70.6% [22.9%] vs 53.9% [30.3%]; P = .02). The intraoperative tip rollover rate was 8% for SME and 0% for SLW. CONCLUSIONS Cochlear implantation with SLW and SME provides comparable improvement in audiologic functioning. SME does not exhibit superior speech recognition outcomes when compared with SLW.
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Affiliation(s)
| | - Nathan T Connell
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Indiana University, Indianapolis, Indiana, USA
| | - Douglas J Totten
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Indiana University, Indianapolis, Indiana, USA
| | - Mitchell T Gray
- School of Medicine, Indiana University, Indianapolis, Indiana, USA
| | - David Pisoni
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Indiana University, Indianapolis, Indiana, USA
| | - Charles W Yates
- School of Medicine, Indiana University, Indianapolis, Indiana, USA.,Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Indiana University, Indianapolis, Indiana, USA
| | - Rick F Nelson
- School of Medicine, Indiana University, Indianapolis, Indiana, USA.,Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Indiana University, Indianapolis, Indiana, USA
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16
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Abstract
Supplemental Digital Content is available in the text. The primary objective of this study is to identify the biographic, audiologic, and electrode position factors that influence speech perception performance in adult cochlear implant (CI) recipients implanted with a device from a single manufacturer. The secondary objective is to investigate the independent association of the type of electrode (precurved or straight) with speech perception.
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Risk Factors for Facial Nerve and Other Nonauditory Side Effects Following Cochlear Implantation. Otol Neurotol 2021; 42:e1022-e1029. [PMID: 34398109 DOI: 10.1097/mao.0000000000003162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The purpose of this study was to characterize a cohort of patients with nonauditory side-effects (NASx) following cochlear implant (CI) surgery. STUDY DESIGN Retrospective case review. SETTING Tertiary referral center. PATIENTS One hundred twenty three multichannel CI recipients with intraoperative facial nerve stimulation (FNS). INTERVENTIONS Intraoperative electrical auditory brainstem responses (eABR) during CI surgery. MAIN OUTCOME MEASURES Nonauditory side effects post-CI activation. RESULTS Intraoperative FNS was identified in 2.26% of patients (123/5441), of whom, 34% (42/123) experienced VII stimulation on CI activation. Pain was experienced by 22% (27/123) and vestibular dysfunction was experienced by 4% (5/123) of cases. All case who experienced pain and/or vestibular NASx also experienced VII stimulation. The majority of cases were managed by CI remapping or observation and habituation.Significant relationships were found between etiology of hearing loss and presence of FNS upon initial activation (p < 0.05). No significance was found between FNS intraoperatively and at initial activation for all assumed mechanisms of hearing loss (p > 0.05) with the exceptions of acquired hearing loss of undetermined etiology and toxic etiology group (p < 0.05).There was no significant impact of implant array design (p > 0.05). CONCLUSIONS This study has characterized patients with NASx in a large cohort of CI patients. One third of cases identified with FNS intraoperatively, developed NASx post-CI activation. Risk factors for NASx postactivation include high-risk etiologies and intraoperative objective measures (i.e., eABR). This may assist surgeons and audiologists to identify at-risk patients who may need modifications in CI program planning.
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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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Ucta C, Mittmann P, Ernst A, Seidl R, Lauer G. Minimizing Intracochlear Pressure: Influence of the Insertion Sheath. Audiol Neurootol 2021; 26:281-286. [PMID: 33647910 DOI: 10.1159/000512466] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 10/21/2020] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Atraumatic cochlear implantation (CI) and insertion of the electrode in particular are major goals of recent CI surgery. Perimodiolar electrode arrays need a stylet or exosheath for insertion. The sheath can influence the intracochlear pressure changes during insertion of the electrode. The aim of this study was to modify the insertion sheath to optimize intracochlear pressure changes. METHODS In an artifical cochlear model, 7 different modified insertion sheaths were used. The intracochlear pressure was measured with a micro-optical sensor in the apical part of the model cochlea. RESULTS Significant lower intracochlear pressure changes were observed when the apical part of the insertion sheath was either shortened or tapered. Modification of the stopper does influence the intracochlear pressure significantly. CONCLUSION Modification of the insertion sheath leads to lower intracochlear pressure gain. The differences and impact on intracochlear pressure changes found in this study underline the importance of even subtle modifications of the electrode insertion technique.
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Affiliation(s)
- Ceyhun Ucta
- Department of Otolaryngology at ukb, Charité Med School Berlin, Hospital of the University of Berlin, Berlin, Germany
| | - Philipp Mittmann
- Department of Otolaryngology at ukb, Charité Med School Berlin, Hospital of the University of Berlin, Berlin, Germany
| | - Arneborg Ernst
- Department of Otolaryngology at ukb, Charité Med School Berlin, Hospital of the University of Berlin, Berlin, Germany
| | - Rainer Seidl
- Department of Otolaryngology at ukb, Charité Med School Berlin, Hospital of the University of Berlin, Berlin, Germany
| | - Gina Lauer
- Department of Otolaryngology at ukb, Charité Med School Berlin, Hospital of the University of Berlin, Berlin, Germany,
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Ordonez F, Sudhoff H, Todt I. Electrophysiological effects of slim straight intracochlear electrode position. J Laryngol Otol 2020; 134:1077-1080. [PMID: 33292876 DOI: 10.1017/s0022215120002534] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVE The electrical current distribution of a cochlear implant electrode within the cochlea is essential for post-operative hearing performance. The slim straight electrode is designed to enable the placement of contacts in a lateral or medial direction to the modiolus. The electrophysiological effect of this different contact direction is so far unknown. The aim of this study was to determine the influence of intracochlear laterally or medially directed electrode contacts on electrophysiological behaviour. METHOD A slim straight electrode was inserted into the cochleae of five patients, and the neural response threshold was measured in a laterally and medially directed contact position. The cochleae in five temporal bone specimens were de-capped allowing an insertional observation of the contact position (lateral versus medial) of the electrode. RESULTS There was no difference in neural response threshold between a lateral and a medial position of the contacts. Temporal bone study indicated no intracochlear torsion of the electrode. CONCLUSION Our study provides evidence that the intracochlear position of slim straight electrode contacts does not affect the neural response threshold.
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Affiliation(s)
- F Ordonez
- Department of Otolaryngology - Head and Neck Surgery, Klinikum Bielefeld, Bielefeld University, Germany
| | - H Sudhoff
- Department of Otolaryngology - Head and Neck Surgery, Klinikum Bielefeld, Bielefeld University, Germany
| | - I Todt
- Department of Otolaryngology - Head and Neck Surgery, Klinikum Bielefeld, Bielefeld University, Germany
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Heshmat A, Sajedi S, Johnson Chacko L, Fischer N, Schrott-Fischer A, Rattay F. Dendritic Degeneration of Human Auditory Nerve Fibers and Its Impact on the Spiking Pattern Under Regular Conditions and During Cochlear Implant Stimulation. Front Neurosci 2020; 14:599868. [PMID: 33328872 PMCID: PMC7710996 DOI: 10.3389/fnins.2020.599868] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 10/22/2020] [Indexed: 12/04/2022] Open
Abstract
Due to limitations of human in vivo studies, detailed computational models enable understanding the neural signaling in the degenerated auditory system and cochlear implants (CIs). Four human cochleae were used to quantify hearing levels depending on dendritic changes in diameter and myelination thickness from type I of the auditory nerve fibers (ANFs). Type I neurons transmit the auditory information as spiking pattern from the inner hair cells (IHCs) to the cochlear nucleus. The impact of dendrite diameter and degree of myelination on neural signal transmission was simulated for (1) synaptic excitation via IHCs and (2) stimulation from CI electrodes. An accurate three-dimensional human cochlear geometry, along with 30 auditory pathways, mimicked the CI environment. The excitation properties of electrical potential distribution induced by two CI were analyzed. Main findings: (1) The unimodal distribution of control dendrite diameters becomes multimodal for hearing loss cases; a group of thin dendrites with diameters between 0.3 and 1 μm with a peak at 0.5 μm appeared. (2) Postsynaptic currents from IHCs excite such thin dendrites easier and earlier than under control conditions. However, this advantage is lost as their conduction velocity decreases proportionally with the diameter and causes increased spike latency and jitter in soma and axon. Firing probability reduces through the soma passage due to the low intracellular current flow in thin dendrites during spiking. (3) Compared with dendrite diameter, variations in myelin thickness have a small impact on spiking performance. (4) Contrary to synaptic excitation, CIs cause several spike initiation sites in dendrite, soma region, and axon; moreover, fiber excitability reduces with fiber diameter. In a few cases, where weak stimuli elicit spikes of a target neuron (TN) in the axon, dendrite diameter reduction has no effect. However, in many cases, a spike in a TN is first initiated in the dendrite, and consequently, dendrite degeneration demands an increase in threshold currents. (5) Threshold currents of a TN and co-stimulation of degenerated ANFs in other frequency regions depend on the electrode position, including its distance to the outer wall, the cochlear turn, and the three-dimensional pathway of the TN.
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Affiliation(s)
- Amirreza Heshmat
- Faculty of Mathematics and Geoinformation, Institute for Analysis and Scientific Computing, Vienna University of Technology, Vienna, Austria.,Laboratory for Inner Ear Biology, Department of Otorhinolaryngology, Medical University of Innsbruck, Innsbruck, Austria
| | - Sogand Sajedi
- Faculty of Mathematics and Geoinformation, Institute for Analysis and Scientific Computing, Vienna University of Technology, Vienna, Austria
| | - Lejo Johnson Chacko
- Laboratory for Inner Ear Biology, Department of Otorhinolaryngology, Medical University of Innsbruck, Innsbruck, Austria
| | - Natalie Fischer
- Laboratory for Inner Ear Biology, Department of Otorhinolaryngology, Medical University of Innsbruck, Innsbruck, Austria
| | - Anneliese Schrott-Fischer
- Laboratory for Inner Ear Biology, Department of Otorhinolaryngology, Medical University of Innsbruck, Innsbruck, Austria
| | - Frank Rattay
- Faculty of Mathematics and Geoinformation, Institute for Analysis and Scientific Computing, Vienna University of Technology, Vienna, Austria
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Canfarotta MW, Dillon MT, Buchman CA, Buss E, O'Connell BP, Rooth MA, King ER, Pillsbury HC, Adunka OF, Brown KD. Long-Term Influence of Electrode Array Length on Speech Recognition in Cochlear Implant Users. Laryngoscope 2020; 131:892-897. [PMID: 32738069 DOI: 10.1002/lary.28949] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 06/17/2020] [Accepted: 06/30/2020] [Indexed: 01/06/2023]
Abstract
OBJECTIVES/HYPOTHESIS Results from a prospective trial demonstrated better speech recognition for cochlear implant (CI) recipients implanted with a long lateral wall electrode array compared to subjects with a short array after 1 year of listening experience. As short array recipients may require an extended adaptation period, this study investigated whether differences in speech recognition continued through 4 years of CI use. STUDY DESIGN Long-term follow-up of a prospective randomized trial. METHODS Subjects were randomized to receive a MED-EL medium (24 mm) or standard (31.5 mm) array. Linear mixed models compared speech recognition between cohorts with word recognition in quiet and sentence recognition in noise at 1, 3, 6, 12, 24, and 48 months postactivation. Postoperative imaging and electric frequency filters were reviewed to assess the influence of frequency-to-place mismatch and angular separation between neighboring contacts, a metric associated with peripheral spectral selectivity. RESULTS Long (31.5 mm) array recipients demonstrated superior speech recognition out to 4 years postactivation. There was a significant effect of angular separation between contacts, with more closely spaced contacts associated with poorer speech recognition. There was no significant effect of mismatch, yet this may have been obscured by changes in frequency filters over time. CONCLUSIONS Conventional MED-EL CI recipients implanted with 31.5-mm arrays experience better speech recognition than 24-mm array recipients, initially and with long-term listening experience. The benefit conferred by longer arrays in the present cohort can be partially attributed to more widely spaced electrode contacts, presumably a result of reduced channel interaction. LEVEL OF EVIDENCE 2 Laryngoscope, 131:892-897, 2021.
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Affiliation(s)
- Michael W Canfarotta
- Department of Otolaryngology-Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, U.S.A
| | - Margaret T Dillon
- Department of Otolaryngology-Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, U.S.A
| | - Craig A Buchman
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St. Louis, Missouri, U.S.A
| | - Emily Buss
- Department of Otolaryngology-Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, U.S.A
| | - Brendan P O'Connell
- Department of Otolaryngology-Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, U.S.A
| | - Meredith A Rooth
- Department of Otolaryngology-Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, U.S.A
| | - English R King
- Department of Audiology, University of North Carolina Health Care, Chapel Hill, North Carolina, U.S.A
| | - Harold C Pillsbury
- Department of Otolaryngology-Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, U.S.A
| | - Oliver F Adunka
- Department of Otolaryngology-Head and Neck Surgery, The Ohio State University, Columbus, Ohio, U.S.A
| | - Kevin D Brown
- Department of Otolaryngology-Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, U.S.A
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Abstract
BACKGROUND The perimodiolar CI532 Slim Modiolar electrode has been designed to bring the electrode contacts close to auditory nerve while reducing cochlear trauma during its insertion. It is currently unknown to what extent the electrode position and electrophysiological outcomes of the Slim Modiolar electrode differ from other perimodiolar electrodes. OBJECTIVES The objective was to compare the electrode position and electrophysiological outcomes between the CI532 Slim Modiolar and CI512 Contour Advance electrode. METHOD Forty-six adult patients received a Slim Modiolar or Contour Advance electrode. Electrode types were compared using intraoperative electrode impedances, evoked compound action potential (ECAP) and stapedius reflex thresholds, as well as position parameters from postoperative computed tomography or digital volume tomography images (medial-lateral position, electrode-to-modiolus distance, insertion angle). RESULTS The medial-lateral position indicates a closer modiolar placement of the Slim Modiolar compared with the Contour Advance. Individual electrode contact measurements, however, showed significantly larger electrode-to-modiolus distances and higher ECAP thresholds for the Slim Modiolar in the basal region. On contacts E20-22 the Slim Modiolar is slightly closer to the modiolus compared with the Contour Advance, but this did not result in lower ECAP thresholds. CONCLUSIONS Perimodiolar electrodes can vary in their intracochlear position, leading to divergent electrophysiological outcomes. To detect these differences, investigations must be done for each electrode contact rather than using a global factor for the whole electrode array. While the electrode dislocation rate is lower with the Slim Modiolar than with the Contour Advance, electrode-to-modiolus proximity is smaller and ECAP thresholds are lower with the Contour Advance in the basal cochlear region.
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24
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Heutink F, Verbist BM, Mens LHM, Huinck WJ, Mylanus EAM. The evaluation of a slim perimodiolar electrode: surgical technique in relation to intracochlear position and cochlear implant outcomes. Eur Arch Otorhinolaryngol 2019; 277:343-350. [PMID: 31650350 PMCID: PMC6981103 DOI: 10.1007/s00405-019-05696-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 10/11/2019] [Indexed: 11/29/2022]
Abstract
Purpose In cochlear implantation (CI), the two factors that are determined by the surgeon with a potential significant impact on the position of the electrode within the cochlea and the potential outcome, are the surgical technique and electrode type. The objective of this prospective study was to evaluate the position of the slim, perimodiolar electrode (SPE), and to study the influence of the SPE position on CI outcome. Methods Twenty-three consecutively implanted, adult SPE candidates were included in this prospective cohort study conducted between December 2016 and April 2019. Mean age at surgery was 59.5 years. Mean preoperative residual hearing was 92.2 dB. Intra-operative fluoroscopy and high-resolution computed tomography scans were performed to evaluate electrode position after insertion using a cochleostomy (CS) approach. Follow-up was 12 months after implantation; residual hearing (6–8 weeks) and speech perception (6–8 weeks and 12 months) were evaluated in relation to the intracochlear SPE position. Results In most patients in whom the SPE was positioned in the scala tympani residual hearing was preserved [mean absolute increase in PTA of 4.4 dB and 77.2% relative hearing preservation (RHP%)]. Translocation into the scala vestibuli occurred in 36% of the insertions, resulting in a mean absolute increase in PTA of 17.9 dB, and a RHP% of 19.2%. Participants with a translocation had poorer speech perception scores at 12-month follow-up. Conclusion Given the incidence of CS-associated translocations with the SPE and the negative effect on outcome, it is advised to insert the SPE using the (extended) round window approach.
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Affiliation(s)
- Floris Heutink
- Department of Otorhinolaryngology, Radboudumc, Route 377, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands. .,Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Route 780, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands.
| | - Berit M Verbist
- Department of Radiology, Radboudumc, Nijmegen, The Netherlands
| | - Lucas H M Mens
- Department of Otorhinolaryngology, Radboudumc, Route 377, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Route 780, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Wendy J Huinck
- Department of Otorhinolaryngology, Radboudumc, Route 377, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Route 780, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Emmanuel A M Mylanus
- Department of Otorhinolaryngology, Radboudumc, Route 377, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Radboudumc, Route 780, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands
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25
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Garaycochea O, Manrique-Huarte R, Lazaro C, Huarte A, Prieto C, Alvarez de Linera-Alperi M, Manrique M. Comparative study of two different perimodiolar and a straight cochlear implant electrode array: surgical and audiological outcomes. Eur Arch Otorhinolaryngol 2019; 277:69-76. [PMID: 31637478 DOI: 10.1007/s00405-019-05680-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 10/01/2019] [Indexed: 10/25/2022]
Abstract
PURPOSE To compare the surgical and audiological outcomes with two perimodiolar electrode arrays (Nucleus 512-Contour Advance® y Nucleus 532-Slim Perimodiolar®) and a straight electrode array (Nucleus 422/522). METHODS Patients were retrospectively selected from our cochlear implant program database. Only patients with a history of bilateral, sensorineural postlingually profound hearing loss who underwent cochlear implant surgery with either a N512, a N532 or a N422 were included. Throughout a year of follow-up, pure tone audiometry (PTA), speech perception, Impedances and T-C Thresholds levels were analyzed. Surgical data were also analyzed. RESULTS 66 patients were included (19-CI532, 20-CI512 and 27-CI422). The most common type of cochlea access with the N532, N512 and N422 was through an extended round window, a promontorial cochleostomy and a pure round window, respectively. No significant differences were observed after 12 months in Mean PTA and Speech recognition. No significant differences were seen in the levels of hearing preservation at frequencies of 250 and 500. The average values of the impedances were significantly higher in the CI group N532 and N422 than in the N512. The mean values of the T and C levels were significantly lower in the CI groups N532 and N422 compared with the N512. CONCLUSIONS No significant differences were observed after 12 months in Mean PTA and Speech recognition; however, a faster acquisition of auditory results were observed in the group of patients treated with the CI N532. The type of electrode array influences in the type of cochleostomy.
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Affiliation(s)
- Octavio Garaycochea
- Department of Otorhinolaryngology, Clinica Universitaria de Navarra, Pamplona, Spain.,University of Navarra, Avenida Pío XII 36, 31008, Pamplona, Spain
| | - Raquel Manrique-Huarte
- Department of Otorhinolaryngology, Clinica Universitaria de Navarra, Pamplona, Spain. .,University of Navarra, Avenida Pío XII 36, 31008, Pamplona, Spain.
| | - Carlos Lazaro
- University of Navarra School of Medicine, Pamplona, Spain
| | - Alicia Huarte
- Department of Otorhinolaryngology, Clinica Universitaria de Navarra, Pamplona, Spain.,University of Navarra, Avenida Pío XII 36, 31008, Pamplona, Spain
| | - Carlos Prieto
- Department of Otorhinolaryngology, Clinica Universitaria de Navarra, Pamplona, Spain.,University of Navarra, Avenida Pío XII 36, 31008, Pamplona, Spain
| | - Marta Alvarez de Linera-Alperi
- Department of Otorhinolaryngology, Clinica Universitaria de Navarra, Pamplona, Spain.,University of Navarra, Avenida Pío XII 36, 31008, Pamplona, Spain
| | - Manuel Manrique
- Department of Otorhinolaryngology, Clinica Universitaria de Navarra, Pamplona, Spain.,University of Navarra, Avenida Pío XII 36, 31008, Pamplona, Spain
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Lauer G, Uçta J, Decker L, Ernst A, Mittmann P. Intracochlear Pressure Changes After Cochlea Implant Electrode Pullback-Reduction of Intracochlear Trauma. Laryngoscope Investig Otolaryngol 2019; 4:441-445. [PMID: 31453355 PMCID: PMC6703119 DOI: 10.1002/lio2.295] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 06/06/2019] [Accepted: 07/01/2019] [Indexed: 12/05/2022] Open
Abstract
Objective Different aspects should be considered to achieve an atraumatic insertion of cochlear implant electrode arrays as an important surgical goal. Intracochlear pressure changes are known to influence the preservation of residual hearing. By using the intraoperative “pullback technique,” an electrode position closer to the modiolus can be achieved than without the pullback. The aim of the present study was therefore to investigate to what extent the pullback technique can influence intracochlear pressure changes. Methods Insertions of cochlear implant electrodes were performed in an artificial cochlear model with two different perimodiolar arrays. Intracochlear pressure changes were recorded with a micro‐optical pressure sensor positioned in the apical part of the cochlear. After complete insertion of the electrode array, a so‐called pullback of the electrode was performed. Results Statistically significant pressure differences were measured if the electrode array was wet (ie, moisturized) during the pullback. Relative pressure changes in electrodes with smaller total volume are lower than pressure changes in larger electrodes. Conclusion The preservation of residual hearing and, thus, the resulting postoperative audiological outcome has a major impact on the quality of life of the patients and has become of utmost importance. Intracochlear pressure changes during the pullback manoeuver are small in absolute terms, but can even be still reduced statistically significantly by a moistening the electrode before insertion. Using the pullback technique in cases with residual hearing does not affect the probability of preservation of residual hearing but could lead to a better audiological outcome. Level of Evidence NA
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Affiliation(s)
- Gina Lauer
- Department of Otolaryngology at UKB, Hospital of the University of Berlin Charité Medical School Berlin Germany
| | - Julica Uçta
- Department of Otolaryngology at UKB, Hospital of the University of Berlin Charité Medical School Berlin Germany
| | - Lars Decker
- Department of Otolaryngology at UKB, Hospital of the University of Berlin Charité Medical School Berlin Germany
| | - Arneborg Ernst
- Department of Otolaryngology at UKB, Hospital of the University of Berlin Charité Medical School Berlin Germany
| | - Philipp Mittmann
- Department of Otolaryngology at UKB, Hospital of the University of Berlin Charité Medical School Berlin Germany
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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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Gomez Serrano M, Patel S, Harris R, Selvadurai D. Initial surgical and clinical experience with the Nucleus CI532 slim modiolar electrode in the UK. Cochlear Implants Int 2019; 20:207-216. [PMID: 30947632 DOI: 10.1080/14670100.2019.1597461] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVE The goal of this work is to describe the first experience in the UK with the slim pre-curved perimodiolar electrode Nucleus CI532 in a continuous series of patients in terms of surgical and clinical reliability and early performance outcomes. METHOD In this retrospective review we describe the complication rate (including electrode array tip fold-over), NRT thresholds, hearing preservation, power efficiency and CI performance outcomes in a continuous series of 40 cochlear implants CI532 performed between October 2016 and November 2017 in 17 adults and 13 children with severe to profound hearing loss. RESULTS Preliminary data from these groups reveals some low-frequency hearing preservation in the CI532 group although none of the patients were conventional hearing preservation candidates. NRT thresholds, power efficiency, and BKB sentences in quiet were measured at 3 and 6 months post activation. There were no significant differences in these results. The average BKB score in quiet increases from 22% pre-operatively to 58% at 3 months and 70% at 6 months. In addition, although hearing preservation was not an objective, low-frequency thresholds were preserved in 20% of cases at 3 and 6 months post-operatively. Complications were observed in 5 cases, one case with non-device related aerocoele and four related to the device array: two cases of tip roll over, one case of the electrode array being placed extra-cochlea, and one case with the electrode buckling into the middle ear. The last 2 cases were dealt with per-operatively. DISCUSSION Our preliminary results with the CI532 implant indicate that it may be reliably placed with standard surgical techniques but care is needed during the deployment of the electrode. Further initial data suggest that switch on and early electrophysiological measures are comparable to the existing CI 512 device. However whilst preliminary, our data suggest that it may be possible to use this electrode for hearing preservation. However, further studies are required to determine its definitive advantage over other electrode designs. CONCLUSION CI532 is a reliable device offering good initial results and could be an option for hearing preservation although further studies are required.
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Affiliation(s)
- Manuel Gomez Serrano
- a St George's Auditory Implant Service, St Georges NHS Foundation Trust London , London , UK
| | - Sharmila Patel
- a St George's Auditory Implant Service, St Georges NHS Foundation Trust London , London , UK
| | - Robert Harris
- a St George's Auditory Implant Service, St Georges NHS Foundation Trust London , London , UK
| | - David Selvadurai
- a St George's Auditory Implant Service, St Georges NHS Foundation Trust London , London , UK
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Responsiveness of the Electrically Stimulated Cochlear Nerve in Children With Cochlear Nerve Deficiency. Ear Hear 2019; 39:238-250. [PMID: 28678078 DOI: 10.1097/aud.0000000000000467] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
OBJECTIVES This study aimed to (1) investigate the responsiveness of the cochlear nerve (CN) to a single biphasic-electrical pulse in implanted children with cochlear nerve deficiency (CND) and (2) compare their results with those measured in implanted children with normal-size CNs. DESIGN Participants included 23 children with CND (CND1 to CND23) and 18 children with normal-size CNs (S1 to S18). All subjects except for CND1 used Cochlear Nucleus cochlear implants with contour electrode arrays in their test ears. CND1 was implanted with a Cochlear Nucleus Freedom cochlear implant with a straight electrode array in the test ear. For each subject, the CN input/output (I/O) function and the refractory recovery function were measured using electrophysiological measures of the electrically evoked compound action potential (eCAP) at multiple electrode sites across the electrode array. Dependent variables included eCAP threshold, the maximum eCAP amplitude, slope of the I/O function, and time-constants of the refractory recovery function. Slopes of I/O functions were estimated using statistical modeling with a sigmoidal function. Recovery time-constants, including measures of the absolute refractory period and the relative refractory period, were estimated using statistical modeling with an exponential decay function. Generalized linear mixed-effect models were used to evaluate the effects of electrode site on the dependent variables measured in children with CND and to compare results of these dependent variables between subject groups. RESULTS The eCAP was recorded at all test electrodes in children with normal-size CNs. In contrast, the eCAP could not be recorded at any electrode site in 4 children with CND. For all other children with CND, the percentage of electrodes with measurable eCAPs decreased as the stimulating site moved in a basal-to-apical direction. For children with CND, the stimulating site had a significant effect on the slope of the I/O functions and the relative refractory period but showed no significant effect on eCAP threshold and the maximum eCAP amplitude. Children with CND had significantly higher eCAP thresholds, smaller maximum eCAP amplitudes, flatter slopes of I/O functions, and longer absolute refractory periods than children with normal-size CNs. There was no significant difference in the relative refractory period measured in these two subject groups. CONCLUSIONS In children with CND, the functional status of the CN varied along the length of the cochlea. Compared with children with normal-size CNs, children with CND showed reduced CN responsiveness to electrical stimuli. The prolonged CN absolute refractory period in children with CND might account for, at least partially, the observed benefit of using relatively slow pulse rate in these patients.
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Galvin KL, Abdi R, Dowell RC, Nayagam B. A Comparison of Electrical Stimulation Levels Across Ears for Children With Sequential Bilateral Cochlear Implants. Ear Hear 2019; 40:1174-1186. [DOI: 10.1097/aud.0000000000000702] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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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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Scalar localisation of peri-modiolar electrodes and speech perception outcomes. The Journal of Laryngology & Otology 2018; 132:1000-1006. [PMID: 30370884 DOI: 10.1017/s0022215118001871] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE To identify the intracochlear electrode position in cochlear implant recipients and determine the correlation to speech perception for two peri-modiolar electrode arrays. METHODS Post-operative cone-beam computed tomography images of 92 adult recipients of the 'CI512' electrode and 18 adult recipients of the 'CI532' electrode were analysed. Phonemes scores were recorded pre-implantation, and at 3 and 12 months post-implantation. RESULTS All CI532 electrodes were wholly within scala tympani. Of the 79 CI512 electrodes intended to be in scala tympani, 58 (73 per cent) were in scala tympani, 14 (17 per cent) were translocated and 7 (9 per cent) were wholly in scala vestibuli. Thirteen CI512 electrodes were deliberately inserted into scala vestibuli. Speech perception scores for post-lingual recipients were higher in the scala tympani group (69.1 per cent) compared with the scala vestibuli (54.2 per cent) and translocation (50 per cent) groups (p < 0.05). Electrode location outside of scala tympani independently resulted in a 10.5 per cent decrease in phoneme scores. CONCLUSION Cone-beam computed tomography was valuable for demonstrating electrode position. The rate of scala tympani insertion was higher in CI532 than in CI512 electrodes. Scala vestibuli insertion and translocation were associated with poorer speech perception outcomes.
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Feng L, Oxenham AJ. Auditory enhancement and the role of spectral resolution in normal-hearing listeners and cochlear-implant users. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2018; 144:552. [PMID: 30180692 PMCID: PMC6072550 DOI: 10.1121/1.5048414] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 06/25/2018] [Accepted: 07/11/2018] [Indexed: 05/17/2023]
Abstract
Detection of a target tone in a simultaneous multi-tone masker can be improved by preceding the stimulus with the masker alone. The mechanisms underlying this auditory enhancement effect may enable the efficient detection of new acoustic events and may help to produce perceptual constancy under varying acoustic conditions. Previous work in cochlear-implant (CI) users has suggested reduced or absent enhancement, due perhaps to poor spatial resolution in the cochlea. This study used a supra-threshold enhancement paradigm that in normal-hearing listeners results in large enhancement effects, exceeding 20 dB. Results from vocoder simulations using normal-hearing listeners showed that near-normal enhancement was observed if the simulated spread of excitation was limited to spectral slopes no shallower than 24 dB/oct. No significant enhancement was observed on average in CI users with their clinical monopolar stimulation strategy. The variability in enhancement between CI users, and between electrodes in a single CI user, could not be explained by the spread of excitation, as estimated from auditory nerve evoked potentials. Enhancement remained small, but did reach statistical significance, under the narrower partial-tripolar stimulation strategy. The results suggest that enhancement may be at least partially restored by improvements in the spatial resolution of current CIs.
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Affiliation(s)
- Lei Feng
- Department of Psychology, University of Minnesota, N218 Elliott Hall, 75 East River Parkway, Minneapolis, Minnesota 55455, USA
| | - Andrew J Oxenham
- Department of Psychology, University of Minnesota, N218 Elliott Hall, 75 East River Parkway, Minneapolis, Minnesota 55455, USA
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DeVries L, Arenberg JG. Psychophysical Tuning Curves as a Correlate of Electrode Position in Cochlear Implant Listeners. J Assoc Res Otolaryngol 2018; 19:571-587. [PMID: 29869047 DOI: 10.1007/s10162-018-0678-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 05/23/2018] [Indexed: 01/04/2023] Open
Abstract
Speech understanding abilities vary widely among cochlear implant (CI) listeners. A potential source of this variability is the electrode-neuron interface (ENI), which includes peripheral factors such as electrode position and integrity of remaining spiral ganglion neurons. Suboptimal positioning of the electrode array has been associated with poorer speech outcomes; however, postoperative computerized tomography (CT) scans are often not available to clinicians. CT-estimated electrode-to-modiolus distance (distance from the inner wall of the cochlea) has been shown to account for some variability in behavioral thresholds. However, psychophysical tuning curves (PTCs) may provide additional insight into site-specific variation in channel interaction. Thirteen unilaterally implanted adults with the Advanced Bionics HiRes90K device participated. Behavioral thresholds and PTCs were collected for all available electrodes with steered quadrupolar (sQP) configuration, using a modified threshold sweep procedure, used in Bierer et al. (Trends Hear 19:1-12, 2015). PTC bandwidths were quantified to characterize channel interaction across the electrode array, and tip shifts were assessed to identify possible contributions of neural dead regions. Broader PTC bandwidths were correlated with electrodes farther from the modiolus, but not correlated with sQP threshold, though a trend was observed. Both measures were affected by scalar location, and PTC tip shifts were observed for electrodes farther from the modiolus. sQP threshold was the only variable correlated with word recognition. These results suggest PTCs may be used as a site-specific measure of channel interaction that correlates with electrode position in some CI listeners.
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Affiliation(s)
- Lindsay DeVries
- Department of Speech and Hearing Sciences, University of Washington, 4131 15th Ave NE, Seattle, WA, 98106, USA.
| | - Julie G Arenberg
- Department of Speech and Hearing Sciences, University of Washington, 4131 15th Ave NE, Seattle, WA, 98106, USA
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Tanamati LF, Goffi-Gomez MVS, Muniz LF, Samuel PA, Wiemes GRM, Lima DP, Curi SB, Onuki LC, Queiroz CF, Capistrano AKB, Moret ALM, Kimura MYT, Oyanguren V, Mauch H. Use of remote control in the intraoperative telemetry of cochlear implant: multicentric study. Braz J Otorhinolaryngol 2018; 85:502-509. [PMID: 29858159 PMCID: PMC9443058 DOI: 10.1016/j.bjorl.2018.04.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 02/18/2018] [Accepted: 04/09/2018] [Indexed: 12/03/2022] Open
Abstract
Introduction The conventional evaluation of neural telemetry and impedance requires the use of the computer coupled to an interface, with software that provides visualization of the stimulus and response. Recently, a remote control (CR220®) was launched in the market, that allows the performance of intraoperative tests with minimal instrumentation. Objective To evaluate the agreement of the impedance values and neural telemetry thresholds, and the time of performance in the conventional procedure and by the remote control. Methods Multicentric prospective cross-sectional study. Intraoperative evaluations of cochlear implants compatible with the use of CR220® were included. The tests were carried out in the 22 electrodes to compare the time of performance in the two situations. The agreement of the neural telemetry threshold values obtained from five electrodes was analyzed, and the agreement of impedance was evaluated by the number of electrodes with altered values in each procedure. Results There were no significant difference between the impedance values. There was a moderate to strong correlation between the electrically-evoked compound action potential thresholds. The mean time to perform the procedures using the CR220 was significantly lower than that with the conventional procedure. Conclusion The use of the CR220 provided successful records for impedance telemetry and automatic neural response telemetry.
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Affiliation(s)
| | | | | | - Paola Angélica Samuel
- Universidade de São Paulo (USP), Faculdade de Medicina, Hospital das Clínicas, São Paulo, SP, Brazil
| | | | | | - Sílvia Badur Curi
- Universidade de Campinas (UNICAMP), Faculdade de Medicina, Hospital das Clínicas, Campinas, SP, Brazil
| | - Lucia Cristina Onuki
- Universidade de Campinas (UNICAMP), Faculdade de Medicina, Hospital das Clínicas, Campinas, SP, Brazil
| | - Carla Fortunato Queiroz
- Universidade do Paraná (UFPR), Faculdade de Medicina, Hospital das Clínicas, Curitiba, PR, Brazil
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Abstract
OBJECTIVE The width of the spread of excitation (SOE) curve has been widely thought to represent an estimate of SOE. Therefore, correlates between psychophysical parameters, such as pitch discrimination and speech perception, and the width of SOE curves, have long been investigated. However, to date, no relationships between these objective and subjective measurements have yet been determined. In a departure from the current thinking, the authors now propose that the SOE curve, recorded with forward masking, is the equivalent of a convolution operation. As such, deconvolution would be expected to retrieve the excitation areas attributable to either masker or probe, potentially more closely revealing the actual neural SOE. This study aimed to develop a new analytical tool with which to derive SOE using this principle. DESIGN Intraoperative SOE curve measurements of 16 subjects, implanted with an Advanced Bionics implant, were analyzed. Evoked compound action potential (ECAP)-based SOE curves were recorded on electrodes 3 to 16, using the forward masker paradigm, with variable masker. The measured SOE curves were then compared with predicted SOE curves, built by the convolution of basic excitation density profiles (EDPs). Predicted SOE curves were fitted to the measured SOEs by iterative adjustment of the EDPs for the masker and the probe. RESULTS It was possible to generate a good fit between the predicted and measured SOE curves, inclusive of their asymmetry. The rectangular EDP was of least value in terms of its ability to generate a good fit; smoother SOE curves were modeled using the exponential or Gaussian EDPs. In most subjects, the EDP width (i.e., the size of the excitation area) gradually changed from wide at the apex of the electrode array, to narrow at the base. A comparison of EDP widths to SOE curve widths, as calculated in the literature, revealed that the EDPs now provide a measure of the SOE that is qualitatively distinct from that provided using conventional methods. CONCLUSIONS This study shows that an eCAP-based SOE curve, measured with forward masking, can be treated as a convolution of EDPs for masker and probe. The poor fit achieved for the measured and modeled data using the rectangular EDP, emphasizes the requirement for a sloping excitation area to mimic actual SOE recordings. Our deconvolution method provides an explanation for the frequently observed asymmetry of SOE curves measured along the electrode array, as this is a consequence of a wider excitation area in the apical part of the cochlea, in the absence of any asymmetry in the actual EDP. In addition, broader apical EDPs underlie the higher eCAP amplitudes found for apical stimulation.
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DeVries L, Arenberg JG. Current Focusing to Reduce Channel Interaction for Distant Electrodes in Cochlear Implant Programs. Trends Hear 2018; 22:2331216518813811. [PMID: 30488764 PMCID: PMC6277758 DOI: 10.1177/2331216518813811] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 10/17/2018] [Accepted: 10/26/2018] [Indexed: 11/17/2022] Open
Abstract
Speech understanding abilities are highly variable among cochlear implant (CI) listeners. Poor electrode-neuron interfaces (ENIs) caused by sparse neural survival or distant electrode placement may lead to increased channel interaction and reduced speech perception. Currently, it is not possible to directly measure neural survival in CI listeners; therefore, obtaining information about electrode position is an alternative approach to assessing ENIs. This information can be estimated with computerized tomography (CT) imaging; however, postoperative CT imaging is not often available. A reliable method to assess channel interaction, such as the psychophysical tuning curve (PTC), offers an alternative way to identify poor ENIs. This study aimed to determine (a) the within-subject relationship between CT-estimated electrode distance and PTC bandwidths, and (b) whether using focused stimulation on channels with suspected poor ENI improves vowel identification and sentence recognition. In 13 CI listeners, CT estimates of electrode-to-modiolus distance and PTCs bandwidths were measured for all available electrodes. Two test programs were created, wherein a subset of electrodes used focused stimulation based on (a) broad PTC bandwidth (Tuning) and (b) far electrode-to-modiolus distance (Distance). Two control programs were also created: (a) Those channels not focused in the Distance program (Inverse-Control), and (b) an all-channel monopolar program (Monopolar-Control). Across subjects, scores on the Distance and Tuning programs were significantly higher than the Inverse-Control program, and similar to the Monopolar-Control program. Subjective ratings were similar for all programs. These findings suggest that focusing channels suspected to have a high degree of channel interaction result in quite different outcomes, acutely.
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Affiliation(s)
- Lindsay DeVries
- Department of Hearing and Speech Sciences, University of Maryland, College Park, MD, USA
| | - Julie G. Arenberg
- Department of Speech and Hearing Sciences, University of Washington, Seattle, WA, USA
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Importance of Perimodiolar Electrode Position for Psychoacoustic Discrimination in Cochlear Implantation. Otol Neurotol 2017; 38:e429-e437. [PMID: 29135866 DOI: 10.1097/mao.0000000000001594] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Aschendorff A, Briggs R, Brademann G, Helbig S, Hornung J, Lenarz T, Marx M, Ramos A, Stöver T, Escudé B, James CJ. Clinical investigation of the Nucleus Slim Modiolar Electrode. Audiol Neurootol 2017; 22:169-179. [PMID: 29059669 DOI: 10.1159/000480345] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 08/11/2017] [Indexed: 11/19/2022] Open
Abstract
AIMS The Nucleus CI532 cochlear implant incorporates a new precurved electrode array, i.e., the Slim Modiolar electrode (SME), which is designed to bring electrode contacts close to the medial wall of the cochlea while avoiding trauma due to scalar dislocation or contact with the lateral wall during insertion. The primary aim of this prospective study was to determine the final position of the electrode array in clinical cases as evaluated using flat-panel volume computed tomography. METHODS Forty-five adult candidates for unilateral cochlear implantation were recruited from 8 centers. Eleven surgeons attended a temporal bone workshop and received further training with a transparent plastic cochlear model just prior to the first surgery. Feedback on the surgical approach and use of the SME was collected via a questionnaire for each case. Computed tomography of the temporal bone was performed postoperatively using flat-panel digital volume tomography or cone beam systems. The primary measure was the final scalar position of the SME (completely in scala tympani or not). Secondly, medial-lateral position and insertion depth were evaluated. RESULTS Forty-four subjects received a CI532. The SME was located completely in scala tympani for all subjects. Pure round window (44% of the cases), extended round window (22%), and inferior and/or anterior cochleostomy (34%) approaches were successful across surgeons and cases. The SME was generally positioned close to the modiolus. Overinsertion of the array past the first marker tended to push the basal contacts towards the lateral wall and served only to increase the insertion depth of the first electrode contact without increasing the insertion depth of the most apical electrode. Complications were limited to tip fold-overs encountered in 2 subjects; both were attributed to surgical error, with both reimplanted successfully. CONCLUSIONS The new Nucleus CI532 cochlear implant with SME achieved the design goal of producing little or no trauma as indicated by consistent scala tympani placement. Surgeons should be carefully trained to use the new deployment method such that tip fold-overs and over insertion may be avoided.
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Cuda D, Murri A. Cochlear implantation with the nucleus slim modiolar electrode (CI532): a preliminary experience. Eur Arch Otorhinolaryngol 2017; 274:4141-4148. [DOI: 10.1007/s00405-017-4774-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 10/11/2017] [Indexed: 10/18/2022]
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Audiological Outcomes and Map Characteristics in Children With Perimodiolar and Slim Straight Array Cochlear Implants in Opposite Ears. Otol Neurotol 2017; 38:e320-e326. [DOI: 10.1097/mao.0000000000001539] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Völker J, Kohm F, Jürgens L, Scherzad A, Schendzielorz P, Schraven SP, Mlynski R, Radeloff A, Hagen R, Rak K. Patterned semiconductor structures modulate neuronal outgrowth: Implication for the development of a neurobionic interface. J Biomed Mater Res A 2017; 106:65-72. [PMID: 28884492 DOI: 10.1002/jbm.a.36203] [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: 06/16/2017] [Revised: 08/09/2017] [Accepted: 08/15/2017] [Indexed: 11/10/2022]
Abstract
Auditory implants stimulate the neurons by broad electrical fields, which leads to a low number of spectral channels. A reduction in the distance between the electrode and the neuronal structures might lead to better electrical transduction. The use of microstructured semiconductors offers a large number of contacts, which could attract neurons and stimulate them individually. To investigate the interaction between neurons and semiconductors, differentiated neuronal precursor cells were cultured on silicon wafers. Different structures were added on the wafers by electron beam lithography, and deep reactive ion etching in different depths (2 and 7 µm). Grooved surfaces guided the neurons and resulted in straight oriented axons, but neuronal outgrowth was impaired by the 7 µm grooves. Within the 7 µm structures, the neuronal cell body was totally encased and the nuclei were deformed from a round to an elliptical shape. On both square and cylindrical structures neuronal bridging could be detected in different forms, either between the tops of the structures or between the bottom and the top. Furthermore, neuronal bridges were established on the lateral part of the structures, and change in direction of neuronal growth was induced by the structure. Finally, it could be shown that neuronal growth cones were particularly attracted by the top of the cylinders, which might allow for the stimulation of neurons via this structure. In conclusion, study results indicate that structured semiconductors can modulate neuronal growth and its direction, offering a novel method for the development of new implants with improved neuronal stimulation. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 65-72, 2018.
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Affiliation(s)
- Johannes Völker
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Wuerzburg, Würzburg, Germany
| | - Fabian Kohm
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Wuerzburg, Würzburg, Germany
| | - Lukas Jürgens
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Wuerzburg, Würzburg, Germany
| | - Agmal Scherzad
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Wuerzburg, Würzburg, Germany
| | - Philipp Schendzielorz
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Wuerzburg, Würzburg, Germany
| | - Sebastian P Schraven
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Wuerzburg, Würzburg, Germany
| | - Robert Mlynski
- Department of Otorhinolaryngology, Head and Neck Surgery "Otto Koerner", Rostock University Medical Center, Rostock, Germany
| | - Andreas Radeloff
- Department of Oto-Rhino-Laryngology, Head and Neck Surgery, University of Oldenburg, Oldenburg, Germany
| | - Rudolf Hagen
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Wuerzburg, Würzburg, Germany
| | - Kristen Rak
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Wuerzburg, Würzburg, Germany
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Abstract
Cochlear implantation (CI) surgery is a very successful technique, performed on more than 300,000 people worldwide. However, since the challenge resides in obtaining an accurate surgical planning, computational models are considered to provide such accurate tools. They allow us to plan and simulate beforehand surgical procedures in order to maximally optimize surgery outcomes, and consequently provide valuable information to guide pre-operative decisions. The aim of this work is to develop and validate computational tools to completely assess the patient-specific functional outcome of the CI surgery. A complete automatic framework was developed to create and assess computationally CI models, focusing on the neural response of the auditory nerve fibers (ANF) induced by the electrical stimulation of the implant. The framework was applied to evaluate the effects of ANF degeneration and electrode intra-cochlear position on nerve activation. Results indicate that the intra-cochlear positioning of the electrode has a strong effect on the global performance of the CI. Lateral insertion provides better neural responses in case of peripheral process degeneration, and it is recommended, together with optimized intensity levels, in order to preserve the internal structures. Overall, the developed automatic framework provides an insight into the global performance of the implant in a patient-specific way. This enables to further optimize the functional performance and helps to select the best CI configuration and treatment strategy for a given patient.
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The Change in Electrical Stimulation Levels During 24 Months Postimplantation for a Large Cohort of Adults Using the Nucleus® Cochlear Implant. Ear Hear 2017; 38:357-367. [DOI: 10.1097/aud.0000000000000405] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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van der Jagt MA, Briaire JJ, Verbist BM, Frijns JH. Comparison of the HiFocus Mid-Scala and HiFocus 1J Electrode Array: Angular Insertion Depths and Speech Perception Outcomes. Audiol Neurootol 2016; 21:316-325. [DOI: 10.1159/000448581] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 07/20/2016] [Indexed: 11/19/2022] Open
Abstract
The HiFocus Mid-Scala (MS) electrode array has recently been introduced onto the market. This precurved design with a targeted mid-scalar intracochlear position pursues an atraumatic insertion and optimal distance for neural stimulation. In this study we prospectively examined the angular insertion depth achieved and speech perception outcomes resulting from the HiFocus MS electrode array for 6 months after implantation, and retrospectively compared these with the HiFocus 1J lateral wall electrode array. The mean angular insertion depth within the MS population (n = 96) was found at 470°. This was 50° shallower but more consistent than the 1J electrode array (n = 110). Audiological evaluation within a subgroup, including only postlingual, unilaterally implanted, adult cochlear implant recipients who were matched on preoperative speech perception scores and the duration of deafness (MS = 32, 1J = 32), showed no difference in speech perception outcomes between the MS and 1J groups. Furthermore, speech perception outcome was not affected by the angular insertion depth or frequency mismatch.
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Hughes ML, Goehring JL, Baudhuin JL, Schmid KK. Effects of stimulus level and rate on psychophysical thresholds for interleaved pulse trains in cochlear implants. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2016; 140:2297. [PMID: 27794318 PMCID: PMC6910005 DOI: 10.1121/1.4963903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 09/09/2016] [Accepted: 09/14/2016] [Indexed: 06/06/2023]
Abstract
This study examined channel interactions using interleaved pulse trains to assess masking and potential facilitative effects in cochlear-implant recipients using clinically relevant stimuli. Psychophysical thresholds were measured for two adjacent mid-array electrodes; one served as the masker and the other as the probe. Two rates representative of those found in present-day strategies were tested: 1700 and 3400 pulses per second per channel. Four masker levels ranging from sub-threshold to loud-but-comfortable were tested. It was hypothesized that low-level maskers would produce facilitative effects, shifting to masking effects at high levels, and that faster rates would yield smaller masking effects due to greater stochastic neural firing patterns. Twenty-nine ears with Cochlear or Advanced Bionics devices were tested. High-level maskers produced more masking than low-level maskers, as expected. Facilitation was not observed for sub-threshold or threshold-level maskers in most cases. High masker levels yielded reduced probe thresholds for two Advanced Bionics subjects. This was partly eliminated with a longer temporal offset between each masker-probe pulse pair, as was used with Cochlear subjects. These findings support the use of temporal gaps between stimulation of subsequent electrodes to reduce channel interactions.
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Affiliation(s)
- Michelle L Hughes
- Boys Town National Research Hospital, 555 North 30th Street, Omaha, Nebraska 68131, USA
| | - Jenny L Goehring
- Boys Town National Research Hospital, 555 North 30th Street, Omaha, Nebraska 68131, USA
| | - Jacquelyn L Baudhuin
- Boys Town National Research Hospital, 555 North 30th Street, Omaha, Nebraska 68131, USA
| | - Kendra K Schmid
- Department of Biostatistics, 984375 University of Nebraska Medical Center, Omaha, Nebraska 68198-4375, USA
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Relationship Between Electrode-to-Modiolus Distance and Current Levels for Adults With Cochlear Implants. Otol Neurotol 2016; 37:31-7. [PMID: 26649603 DOI: 10.1097/mao.0000000000000896] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
HYPOTHESIS Electrode-to-modiolus distance is correlated with clinically programmed stimulation levels. BACKGROUND Conventional wisdom has long supposed a significant relationship between cochlear implant (CI) stimulation levels and electrode-to-modiolus distance; however, to date, no such formal investigation has been completed. Thus, the purpose of this project was to investigate the relationship between stimulation levels and electrode-to-modiolus distance. A strong correlation between the two would suggest that stimulation levels might be used to estimate electrode-to-modiolus geometry. METHODS Electrode-to-modiolus distance was determined via CT imaging using validated CI position analysis software in 137 implanted ears from the three manufacturers holding FDA approval in the United States. Analysis included 2,365 total electrodes, with 1,472 from precurved arrays. Distances were compared to clinically programmed C/M levels that were converted to charge units. RESULTS Mean modiolar distance with perimodiolar and lateral wall electrodes was 0.47 and 1.15 mm, respectively. Mean suprathreshold charge values were significantly different between each manufacturer. When combining all data, we found a moderate positive correlation (r = 0.367, p < 0.01) that was driven both by the different charge values across companies, and that the company with the highest mean charge values only offers straight electrode arrays. When grouped by electrode type, however, we found a weak correlation (r = 0.12, p < 0.01) for perimodiolar array electrodes only. When considering a single array type from any one manufacturer, only one was observed where distance mildly predicted charge. CONCLUSION Our results suggest that electrode distance minimally contributes to the current level required for suprathreshold stimulation.
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ECAP analysis in cochlear implant patients as a function of patient's age and electrode-design. Eur Ann Otorhinolaryngol Head Neck Dis 2016; 133 Suppl 1:S1-3. [DOI: 10.1016/j.anorl.2016.04.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 03/26/2016] [Accepted: 04/28/2016] [Indexed: 11/18/2022]
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Insertion trauma of a cochlear implant electrode array with Nitinol inlay. Eur Arch Otorhinolaryngol 2016; 273:3573-3585. [PMID: 26961519 DOI: 10.1007/s00405-016-3955-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 02/26/2016] [Indexed: 10/22/2022]
Abstract
The integration of a shape memory actuator is a potential mechanism to achieve a consistent perimodiolar position after electrode insertion during cochlear implant surgery. After warming up, and therefore activation of the shape memory effect, the electrode array will change from a straight configuration into a spiral shaped one leading to a final position close to the modiolus. The aim of this study was to investigate whether the integration of an additional thin wire (referred to as an "inlay") made of Nitinol, a well-established shape memory alloy, in a conventional hearing preservation electrode array will affect the insertion behaviour in terms of increased risk of insertion trauma. Six conventional Hybrid-L electrode arrays (Cochlear Ltd., Sydney, Australia) were modified to incorporate a wire inlay made of Nitinol. The diameter of the wires was 100 µm with a tapered tip region. Electrodes were inserted into human temporal bone specimens using a standard surgical approach. After insertion and embedding in epoxy resin, histological sections were prepared to evaluate insertion trauma. Insertion was straightforward and no difficulties were observed. The addition of a shape memory wire, thin but also strong enough to curl the electrode array, does not result in histologically detectable insertion trauma. Atraumatic insertion seems possible.
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DeVries L, Scheperle R, Bierer JA. Assessing the Electrode-Neuron Interface with the Electrically Evoked Compound Action Potential, Electrode Position, and Behavioral Thresholds. J Assoc Res Otolaryngol 2016; 17:237-52. [PMID: 26926152 DOI: 10.1007/s10162-016-0557-9] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 02/04/2016] [Indexed: 11/26/2022] Open
Abstract
Variability in speech perception scores among cochlear implant listeners may largely reflect the variable efficacy of implant electrodes to convey stimulus information to the auditory nerve. In the present study, three metrics were applied to assess the quality of the electrode-neuron interface of individual cochlear implant channels: the electrically evoked compound action potential (ECAP), the estimation of electrode position using computerized tomography (CT), and behavioral thresholds using focused stimulation. The primary motivation of this approach is to evaluate the ECAP as a site-specific measure of the electrode-neuron interface in the context of two peripheral factors that likely contribute to degraded perception: large electrode-to-modiolus distance and reduced neural density. Ten unilaterally implanted adults with Advanced Bionics HiRes90k devices participated. ECAPs were elicited with monopolar stimulation within a forward-masking paradigm to construct channel interaction functions (CIF), behavioral thresholds were obtained with quadrupolar (sQP) stimulation, and data from imaging provided estimates of electrode-to-modiolus distance and scalar location (scala tympani (ST), intermediate, or scala vestibuli (SV)) for each electrode. The width of the ECAP CIF was positively correlated with electrode-to-modiolus distance; both of these measures were also influenced by scalar position. The ECAP peak amplitude was negatively correlated with behavioral thresholds. Moreover, subjects with low behavioral thresholds and large ECAP amplitudes, averaged across electrodes, tended to have higher speech perception scores. These results suggest a potential clinical role for the ECAP in the objective assessment of individual cochlear implant channels, with the potential to improve speech perception outcomes.
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Affiliation(s)
- Lindsay DeVries
- Department of Speech and Hearing Sciences, University of Washington, 4131 15th Ave NE, Seattle, WA, 98105, USA.
| | - Rachel Scheperle
- Department of Communication Sciences and Disorders, Wendell Johnson Speech and Hearing Center, University of Iowa, Iowa City, Iowa, 52242, USA
| | - Julie Arenberg Bierer
- Department of Speech and Hearing Sciences, University of Washington, 4131 15th Ave NE, Seattle, WA, 98105, USA
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