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Ries M, Kelava I, Ajduk J, Košec A, Žaja R, Trotić R. Correlation between neural response telemetry measurements and fitting levels. Int J Pediatr Otorhinolaryngol 2024; 182:112001. [PMID: 38885546 DOI: 10.1016/j.ijporl.2024.112001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Revised: 05/30/2024] [Accepted: 06/02/2024] [Indexed: 06/20/2024]
Abstract
INTRODUCTION The neural response telemetry (NRT) is a standard procedure in cochlear implantation mostly used to determine the functionality of implanted device and to check auditory nerve responds to the stimulus. Correlation between NRT measurements and subjective threshold (T) and maximum comfort (C) levels has been reported but results are inconsistent, and it is still not clear which of the NRT measurements could be the most useful in predicting fitting levels. PURPOSE In our study we aimed to investigate which NRT measurement corresponds better to fitting levels. Impedance (IMP), Evoked Action Potential (ECAP) threshold and amplitude growth function (AGF) slope values were included in the study. Also, we tried to identify cochlear area at which the connection between NRT measurements and fitting levels would be the most pronounced. MATERIALS AND METHODS Thirty-one children implanted with Cochlear device were included in this retrospective study. IMP, ECAP thresholds and AGF were obtained intra-operatively and 12 months after surgery at electrodes 5, 11 and 19 as representative for each part of cochlea. Subjective T and C levels were obtained 12 months after the surgery during cochlear fitting. RESULTS ECAP thresholds obtained 12 months after surgery showed statistically significant correlation to both T and C levels at all 3 selected electrodes. IMP correlated with C levels while AGF showed tendency to correlate with T levels. However, these correlations were not statistically significant for all electrodes. CONCLUSION ECAP threshold measurements correlated to T and C values better than AGF slope and IMP. Measurements obtained twelve months after surgery seems to be more predictive of T and C values compared to intra-operative measurements. The best correlation between ECAP threshold and T and C values was found at electrode 11 suggesting NRT measurements at mid-portion cochlear region to be the most useful in predicting fitting levels.
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Affiliation(s)
- Mihael Ries
- Department of Otorhinolaryngology, Sisters of Charity University Hospital Center, Vinogradska Cesta 29, Zagreb, Croatia; School of Medicine, University of Zagreb, Šalata 3a, Zagreb, Croatia
| | - Iva Kelava
- Department of Otorhinolaryngology, Sisters of Charity University Hospital Center, Vinogradska Cesta 29, Zagreb, Croatia.
| | - Jakov Ajduk
- Department of Otorhinolaryngology, Sisters of Charity University Hospital Center, Vinogradska Cesta 29, Zagreb, Croatia; School of Medicine, University of Zagreb, Šalata 3a, Zagreb, Croatia
| | - Andro Košec
- Department of Otorhinolaryngology, Sisters of Charity University Hospital Center, Vinogradska Cesta 29, Zagreb, Croatia; School of Medicine, University of Zagreb, Šalata 3a, Zagreb, Croatia
| | - Roko Žaja
- School of Medicine, University of Zagreb, Šalata 3a, Zagreb, Croatia
| | - Robert Trotić
- Department of Otorhinolaryngology, Sisters of Charity University Hospital Center, Vinogradska Cesta 29, Zagreb, Croatia
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Espina González C, Morant Ventura A, Pla Gil I, Aragonés Redó M, Pérez Carbonell T, Marco Algarra J. Variation of electrical impedance over 5 years post-implantation and relationship with the maximum comfort level (MCL) in adults with cochlear implants. ACTA OTORRINOLARINGOLOGICA ESPANOLA 2024; 75:23-30. [PMID: 38224870 DOI: 10.1016/j.otoeng.2024.01.004] [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: 09/05/2022] [Accepted: 04/29/2023] [Indexed: 01/17/2024]
Abstract
INTRODUCTION The maximum comfort level (MCL), threshold level (THR) and electrical impedance change in the postoperative period of the cochlear implant for months until they stabilize. The objective of this article is to establish the variation during 5 post-surgical years of impedance, and its relationship with MCL in unilaterally implanted adults. METHODS Retrospective study over 5 years, with 78 adult patients implanted with MED-EL in a tertiary hospital from the year 2000 to 2015. The variation in impedance, MCL and the relationship between them were analyzed in basal (9-12), medial (5-8) and apical electrodes (1-4), performing an inferential ANOVA analysis of repeated measures with comparisons between consecutive times, corrected with Bonferroni criteria. RESULTS 33 men (42.3%) and 45 women (57.7%), with a mean age of 52.7±14.6 years. "Stability" was considered the time of follow-up without statistically significant differences between one visit and the next. Changes in impedance in medial electrodes ceased to be statistically significant at 3 months, and in apicals at 6 months, with mean values of 5.84 and 6.43kΩ. MCL stabilized at 2 years in basal and apical electrodes, and at 3 years in medial, with mean values of 24.9, 22.7, and 25.6qu. There was a correlation between MCL and impedance in medium electrodes up to 3 months and in apical ones up to one year. CONCLUSIONS Electrical impedance drops significantly in medial and apical electrodes up to 3 and 6 months. MCL increases significantly up to two years. Impedance is related to MCL up to 6 months.
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Affiliation(s)
- Clara Espina González
- Servicio de Otorrinolaringología, Hospital Clínico Universitario de Valencia, Universitat de València, Valencia, Spain; Servicio de Otorrinolaringología, Hospital del Mar, Barcelona, Spain.
| | - Antonio Morant Ventura
- Servicio de Otorrinolaringología, Hospital Clínico Universitario de Valencia, Universitat de València, Valencia, Spain
| | - Ignacio Pla Gil
- Servicio de Otorrinolaringología, Hospital Clínico Universitario de Valencia, Universitat de València, Valencia, Spain
| | - María Aragonés Redó
- Servicio de Otorrinolaringología, Hospital Clínico Universitario de Valencia, Universitat de València, Valencia, Spain; Servicio de Otorrinolaringología, Hospital Arnau de Vilanova, Valencia, Spain
| | - Tomás Pérez Carbonell
- Servicio de Otorrinolaringología, Hospital Clínico Universitario de Valencia, Universitat de València, Valencia, Spain
| | - Jaime Marco Algarra
- Servicio de Otorrinolaringología, Hospital Clínico Universitario de Valencia, Universitat de València, Valencia, Spain
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Eitutis ST, Tam YC, Roberts I, Swords C, Tysome JR, Donnelly NP, Axon PR, Bance ML. Detecting and managing partial shorts in Cochlear implants: A validation of scalp surface potential testing. Clin Otolaryngol 2022; 47:641-649. [PMID: 35833359 DOI: 10.1111/coa.13963] [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: 10/04/2021] [Revised: 05/18/2022] [Accepted: 06/21/2022] [Indexed: 01/07/2023]
Abstract
OBJECTIVE To investigate the value of scalp surface potentials to identify and manage partial short circuits to ground in cochlear implant electrodes. DESIGN A retrospective review of patients with suspected partial short circuits. MAIN OUTCOME MEASURE Electrical output of individual electrodes was measured using scalp surface potentials for patients reporting a change in hearing function. Electrical output was compared to functional performance and impedance measurements to determine if devices with suspected partial short circuits were experiencing a decrease in performance as a result of reduced electrical output. Electrical output was checked in an artificial cochlea for two implants following explant surgery to confirm scalp surface potential results. RESULTS All patients with suspected partial short circuits (n = 49) had reduced electrical output, a drop in impedances to approximately ½ of previously stable measurements or to below 2 kΩ, an atypical electrical field measurement (EFI) and a decline in hearing function. Only devices with an atypical EFI showed reduced electrical output. Results of scalp based surface potentials could be replicated in an artificial cochlea following explantation of the device. All explant reports received to date (n = 42) have confirmed partial short circuits, with an additional four devices failing integrity tests. CONCLUSION Surface potential measurements can detect partial shorts and had 100% correlation with atypical EFI measurements, which are characteristic of a partial short to ground in this device. Surface potentials can help determine the degree to which the electrode array is affected, particularly when behavioural testing is limited or not possible.
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Affiliation(s)
- Susan T Eitutis
- Cambridge Hearing Group, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,Emmeline Centre, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Yu Chuen Tam
- Cambridge Hearing Group, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,Emmeline Centre, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Iwan Roberts
- Cambridge Hearing Group, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Chloe Swords
- Cambridge Hearing Group, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,Department of ENT, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - James R Tysome
- Cambridge Hearing Group, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,Department of ENT, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Neil P Donnelly
- Department of ENT, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Patrick R Axon
- Department of ENT, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Manohar L Bance
- Cambridge Hearing Group, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,Department of ENT, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
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Brotto D, Caserta E, Sorrentino F, Favaretto N, Marioni G, Martini A, Bovo R, Gheller F, Trevisi P. Long-Term Impedance Trend in Cochlear Implant Users with Genetically Determined Congenital Profound Hearing Loss. J Am Acad Audiol 2022; 33:105-114. [PMID: 35577055 DOI: 10.1055/s-0041-1739290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND Impedance is a basic parameter registered at any cochlear implant (CI) fitting section. It is useful in monitoring electrode functioning and the status of the surrounding anatomical structures. PURPOSE The main aim of this study is to evaluate the 5-year impedance-value trend in patients affected by congenital genetically determined profound hearing loss implanted with Cochlear Nucleus devices. RESEARCH DESIGN Observational, retrospective, monocentric study. STUDY SAMPLE Twenty-seven consecutive patients (9 females: 12.0 ± 7.6 years old; range: 4.2-40.4) with genetic diagnosis of GJB2 mutation causing congenital profound hearing loss who underwent cochlear implantation from 2010 to 2020 with good auditory benefit. INTERVENTION Impedance values of the CIs were obtained from the CIs' programming software that registers those parameters for each follow-up section of each patient. DATA COLLECTION AND ANALYSIS Impedance values were measured over time (activation, 6, 12, 24, and 60 months after cochlear implantation), for each of the 22 electrodes, in common ground, monopolar 1, monopolar 2, and monopolar 1 + 2 stimulation modes. RESULTS A significant variation was found between CI activation and 6-month follow-up. This difference was found for each of the 22 electrodes. Electrodes 1 to 4 showed higher impedance values compared with all other electrodes in each time interval. Repeated-measures analysis of variance ruled out significant variations in impedance values from 6-month to 5-year follow-up. CONCLUSIONS Impedance values were extremely stable after activation, at least for the first 5 years. In these cases, even minimal impedance variations should be carefully evaluated for their possible implications on hearing performance.
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Affiliation(s)
- Davide Brotto
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Ezio Caserta
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Flavia Sorrentino
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Niccolò Favaretto
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Gino Marioni
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Alessandro Martini
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Roberto Bovo
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Flavia Gheller
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Patrizia Trevisi
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
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Recording EEG in Cochlear Implant Users: Guidelines for Experimental Design and Data Analysis for Optimizing Signal Quality and Minimizing Artifacts. J Neurosci Methods 2022; 375:109592. [PMID: 35367234 DOI: 10.1016/j.jneumeth.2022.109592] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 03/26/2022] [Accepted: 03/27/2022] [Indexed: 11/22/2022]
Abstract
Cochlear implants (CI) are neural prostheses that can restore hearing in individuals with severe to profound hearing loss. Although CIs significantly improve quality of life, clinical outcomes are still highly variable. An important part of this variability is explained by the brain reorganization following cochlear implantation. Therefore, clinicians and researchers are seeking objective measurements to investigate post-implantation brain plasticity. Electroencephalography (EEG) is a promising technique because it is objective, non-invasive, and implant-compatible, but is nonetheless susceptible to massive artifacts generated by the prosthesis's electrical activity. CI artifacts can blur and distort brain responses; thus, it is crucial to develop reliable techniques to remove them from EEG recordings. Despite numerous artifact removal techniques used in previous studies, there is a paucity of documentation and consensus on the optimal EEG procedures to reduce these artifacts. Herein, and through a comprehensive review process, we provide a guideline for designing an EEG-CI experiment minimizing the effect of the artifact. We provide some technical guidance for recording an accurate neural response from CI users and discuss the current challenges in detecting and removing CI-induced artifacts from a recorded signal. The aim of this paper is also to provide recommendations to better appraise and report EEG-CI findings.
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An Innovative Method for Trans-Impedance Matrix Interpretation in Hearing Pathologies Discrimination. Med Eng Phys 2022; 102:103771. [DOI: 10.1016/j.medengphy.2022.103771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 12/13/2021] [Accepted: 02/06/2022] [Indexed: 11/23/2022]
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Söderqvist S, Lamminmäki S, Aarnisalo A, Hirvonen T, Sinkkonen ST, Sivonen V. Intraoperative transimpedance and spread of excitation profile correlations with a lateral-wall cochlear implant electrode array. Hear Res 2021; 405:108235. [PMID: 33901994 DOI: 10.1016/j.heares.2021.108235] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 03/21/2021] [Accepted: 03/25/2021] [Indexed: 01/18/2023]
Abstract
A limiting factor of cochlear implant technology is the spread of electrode-generated intracochlear electrical field (EF) leading to spread of neural excitation (SOE). In this study, we investigated the relation of the spread of the intracochlear EF, assessed via transimpedance matrix (TIM), and SOE. A total of 43 consecutive patients (ages 0.7-82 years; 31.0 ± 25.7 years, mean ± SD) implanted with a Cochlear Nucleus CI522 or CI622 cochlear implant with Slim Straight electrode array (altogether 51 ears) were included in the study. Cochlear nerve was visualized for all patients in preoperative imaging and there were no cochlear anomalies in the study sample. The stimulated electrodes were in the basal, middle, and apical parts of the electrode array (electrode numbers 6, 11, and 19, respectively). The stimulation level was 210 CL on average for the TIM measurement and always 230 CL for the SOE measurement. Approximately 90% of the individual TIM and SOE profiles correlated with each other (p < .05; r = 0.61-0.99). Also, the widths of the TIM and SOE peaks, computed at 50% of the maximum height, exhibited a weak correlation (r = 0.39, p = .007). The 50% widths of TIM and SOE were the same only in the apical part of the electrode array; in the basal part SOE was wider than TIM, and in the middle part TIM was wider than SOE (p < .01 and p = .048, respectively). Within each measurement, TIM 50% widths were different between all three parts of the electrode array, while for SOE, only the basal electrode differed from the middle electrode. Finally, the size of the cochlea and the 50% widths of TIM and SOE had the strongest correlation in the middle part of the electrode array (r = -0.63, and -0.37, respectively). Our results suggest that there is a correlation between the spread of intracochlear EF and neural SOE at least in the apical part of the electrode array used in this study, and that larger cochleae are associated with more focused TIM and SOE.
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Affiliation(s)
- Samuel Söderqvist
- Department of Otorhinolaryngology - Head and Neck Surgery, Head and Neck Center, Helsinki University Hospital and University of Helsinki, Kasarmikatu 11-13, 00130 Helsinki, Finland.
| | - Satu Lamminmäki
- Department of Otorhinolaryngology - Head and Neck Surgery, Head and Neck Center, Helsinki University Hospital and University of Helsinki, Kasarmikatu 11-13, 00130 Helsinki, Finland
| | - Antti Aarnisalo
- Department of Otorhinolaryngology - Head and Neck Surgery, Head and Neck Center, Helsinki University Hospital and University of Helsinki, Kasarmikatu 11-13, 00130 Helsinki, Finland
| | - Timo Hirvonen
- Department of Otorhinolaryngology - Head and Neck Surgery, Head and Neck Center, Helsinki University Hospital and University of Helsinki, Kasarmikatu 11-13, 00130 Helsinki, Finland
| | - Saku T Sinkkonen
- Department of Otorhinolaryngology - Head and Neck Surgery, Head and Neck Center, Helsinki University Hospital and University of Helsinki, Kasarmikatu 11-13, 00130 Helsinki, Finland
| | - Ville Sivonen
- Department of Otorhinolaryngology - Head and Neck Surgery, Head and Neck Center, Helsinki University Hospital and University of Helsinki, Kasarmikatu 11-13, 00130 Helsinki, Finland
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Variability of fitting parameters across cochlear implant centres. Eur Arch Otorhinolaryngol 2021; 278:4671-4679. [PMID: 33388985 DOI: 10.1007/s00405-020-06572-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 12/12/2020] [Indexed: 10/22/2022]
Abstract
OBJECTIVE As a follow-up to the studies by Vaerenberg et al. (Sci World J 501738:1-12, 2014) and Browning et al. (Cochlear Implant Int 21(3):1-13, 2020), who used questionnaires, we determined whether there are between-centre variations in the fitting of cochlear implants by analysing the methodology, fitting parameters and hearing results of patients from four centres with real data. The purpose of this study is to highlight the lack of streamlined mapping guides and outcome measures with respect to cochlear implant (CI) fittings. METHODS A retrospective study with ninety-seven post-lingual adults with a nucleus cochlear implant placed between 2003 and 2013 was included to ensure at least 5 years of follow-up. The studied data were as follows: the methodology, including the fitter's professional background, the method of activation, the sequence of fitting sessions, the objectives measures and hearing outcomes; and the fitting parameters, including the speech processors, programming strategy, stimulation mode, T and C levels, T-SPL and C-SPL, maxima, pulse width, loudness growth and hearing results. RESULTS This investigation highlights some common practices across professionals and CI centres: the activation of a CI is behavioural; impedances are systematically measured at each fitting; and some parameters are rarely modified. However, there are also differences, either between centres, such as the sequences of fitting sessions (p < 0.05) or their approach to spectral bands (p < 0.05), or even within centres, such as the policy regarding T and C levels at high frequencies compared to those at low and mid-frequencies. CONCLUSION There are important variations between and within centres that reflect a lack of CI-related policies and outcome measures in the fitting of CI. CLINICAL TRIALS REGISTRY NCT03700268.
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Impedance Values Do Not Correlate With Speech Understanding in Cochlear Implant Recipients. Otol Neurotol 2020; 41:e1029-e1034. [PMID: 32675728 DOI: 10.1097/mao.0000000000002743] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To evaluate a possible correlation between impedance values and speech perception after cochlear implantation. STUDY DESIGN Retrospective chart review. SETTING Tertiary referral center. PATIENTS AND INTERVENTION All patients implanted with a MedEl Flex28 device in our department with complete audiometric data (Freiburger monosyllabic testing at 65 dB, Hochmaier-Schulz-Moser testing in quiet and in 10 dB noise) and impedance measurements at the 1-year refitting appointment were enrolled in this study. Further inclusion criteria were age > 17 years, native speakers, and no use of electric-acoustic-stimulation. MAIN OUTCOME MEASURES Mean values for impedances were calculated over all electrode contacts and separately for basal, medial, and apical regions. These data were correlated statistically (Pearson's correlation) with speech testing results. Furthermore, groups of patients with extreme values were built and compared against each other and against the rest of the collective. RESULTS Impedance values did not correlate significantly with speech performance in any of the audiometric tests neither for all electrode contacts nor for specific clusters of contacts. Patients with the lowest impedances did not perform statistically different than patients with the highest impedances in any condition. CONCLUSION To our knowledge, this is the first data on a possible correlation between impedances and speech perception. The extent of the impedances as a benchmark for a good performance in speech discrimination tests could not be verified. Further prospective studies, possibly with more precise diagnostic tools, should be carried out to define the value of impedance measurements for cochlear implantation provision.
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Velandia S, Martinez D, Goncalves S, Pena S, Bas E, Ein L, Prentiss S, Telischi F, Angeli S, Dinh CT. Effect of age, electrode array, and time on cochlear implant impedances. Cochlear Implants Int 2020; 21:344-352. [PMID: 32640889 DOI: 10.1080/14670100.2020.1788859] [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] [Indexed: 10/23/2022]
Abstract
Objectives: To determine the impact of age, electrode array, and time on impedance patterns in cochlear implant (CI) patients. Methods: A retrospective case review was performed on 98 patients implanted with the CI24RE perimodiolar (PM) and CI422 lateral wall (LW) arrays between 2010 and 2014 to assess impedances at the 1 week and 3-6 month visit after initial stimulation (IS). Results: With respect to age, impedances were higher in young patients compared to older patients in the middle and apical turns. With time, there were significant reductions in impedances across most electrodes. Electrode array type also had a significant impact on impedance measurements with PM and LW arrays having higher impedances in the basal turn and apical turns, respectively. Furthermore, PM arrays demonstrated significantly lower impedances in the middle and apical turn with time, when compared to LW arrays. Conclusions: Age, electrode array, and time can independently affect CI impedances. Moreover, we show that PM arrays may be advantageous to LW arrays, due to demonstrated lower impedances in the middle and apical turns long term. Understanding the impact of impedance on speech discrimination and determining the intracochlear processes that contribute to differences in impedance are future research directions.
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Affiliation(s)
- Sandra Velandia
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Diane Martinez
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Stefania Goncalves
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Stefanie Pena
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Esperanza Bas
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Liliana Ein
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Sandra Prentiss
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Fred Telischi
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Simon Angeli
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Christine T Dinh
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
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Fayed EA, Zaghloul HS, Morgan AE. Electrode impedance changes over time in MED El cochlear implant children recipients: Relation to stimulation levels and behavioral measures. Cochlear Implants Int 2020; 21:192-197. [DOI: 10.1080/14670100.2020.1716464] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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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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Liu X, Xie L, Wang Y, Yang B. Lower initial electrode impedances in minimally invasive cochlear implantation. Acta Otolaryngol 2019; 139:389-395. [PMID: 30836805 DOI: 10.1080/00016489.2019.1571285] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
BACKGROUND The round window approach and the cochleostomy approach are two widely practiced methods to insert cochlear implant electrode arrays. Yet, there is no consensus on which is more minimally invasive. OBJECTIVE To compare the initial electrode impedance (EI) values and the incidence of abnormal electrodes of the round window approach and the cochleostomy approach, and to evaluate the effects of surgical techniques on the intracochlear microenvironment. MATERIAL AND METHODS One hundred and seventy-one patients received a unilateral Nucleus cochlear implant. Eighty-two patients were implanted using the round window approach, and 89 patients were implanted using the cochleostomy approach. EI was measured immediately after closure of the incision. RESULTS The round window group had lower average initial EI values than the cochleostomy group. For the EI values at each position, statistically significant differences were found in the basal-middle region (Electrode 1-14), but not in the middle-apical region (Electrode 15-22) of the electrode arrays. A lower incidence of high-impedance electrodes was found in the round window group. CONCLUSIONS The round window approach leads to lower initial EI and less disturbance to the intracochlear microenvironment.
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Affiliation(s)
- Xiao Liu
- Department of Otorhinolaryngology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, People’s Republic of China
| | - Lulu Xie
- Department of Otorhinolaryngology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, People’s Republic of China
| | - Yunxiu Wang
- Department of Otorhinolaryngology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, People’s Republic of China
| | - Beibei Yang
- Department of Otorhinolaryngology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, People’s Republic of China
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14
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DiNino M, O'Brien G, Bierer SM, Jahn KN, Arenberg JG. The Estimated Electrode-Neuron Interface in Cochlear Implant Listeners Is Different for Early-Implanted Children and Late-Implanted Adults. J Assoc Res Otolaryngol 2019; 20:291-303. [PMID: 30911952 PMCID: PMC6513958 DOI: 10.1007/s10162-019-00716-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Accepted: 03/03/2019] [Indexed: 12/01/2022] Open
Abstract
Cochlear implant (CI) programming is similar for all CI users despite limited understanding of the electrode-neuron interface (ENI). The ENI refers to the ability of each CI electrode to effectively stimulate target auditory neurons and is influenced by electrode position, neural health, cochlear geometry, and bone and tissue growth in the cochlea. Hearing history likely affects these variables, suggesting that the efficacy of each channel of stimulation differs between children who were implanted at young ages and adults who lost hearing and received a CI later in life. This study examined whether ENI quality differed between early-implanted children and late-implanted adults. Auditory detection thresholds and most comfortable levels (MCLs) were obtained with monopolar and focused electrode configurations. Channel-to-channel variability and dynamic range were calculated for both types of stimulation. Electrical field imaging data were also acquired to estimate levels of intracochlear resistance. Children exhibited lower average auditory perception thresholds and MCLs compared with adults, particularly with focused stimulation. However, neither dynamic range nor channel-to-channel threshold variability differed between groups, suggesting that children’s range of perceptible current was shifted downward. Children also demonstrated increased intracochlear resistance levels relative to the adult group, possibly reflecting greater ossification or tissue growth after CI surgery. These results illustrate physical and perceptual differences related to the ENI of early-implanted children compared with late-implanted adults. Evidence from this study demonstrates a need for further investigation of the ENI in CI users with varying hearing histories.
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Affiliation(s)
- Mishaela DiNino
- Department of Psychology, Carnegie Mellon University, 5000 Forbes, Ave., Pittsburgh, PA, 15213, USA.
| | - Gabrielle O'Brien
- Department of Speech and Hearing Sciences, University of Washington, 1417 NE 42nd St., Box 354875, Seattle, WA, 98105, USA
| | - Steven M Bierer
- Department of Speech and Hearing Sciences, University of Washington, 1417 NE 42nd St., Box 354875, Seattle, WA, 98105, USA
| | - Kelly N Jahn
- Department of Speech and Hearing Sciences, University of Washington, 1417 NE 42nd St., Box 354875, Seattle, WA, 98105, USA
| | - Julie G Arenberg
- Department of Otolaryngology, Massachusetts Eye and Ear, Harvard Medical School, 243 Charles St., Boston, MA, 02114, USA
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15
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Sanderson AP, Rogers ETF, Verschuur CA, Newman TA. Exploiting Routine Clinical Measures to Inform Strategies for Better Hearing Performance in Cochlear Implant Users. Front Neurosci 2019; 12:1048. [PMID: 30697145 PMCID: PMC6340939 DOI: 10.3389/fnins.2018.01048] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 12/24/2018] [Indexed: 11/21/2022] Open
Abstract
Neuroprostheses designed to interface with the nervous system to replace injured or missing senses can significantly improve a patient's quality of life. The challenge remains to provide implants that operate optimally over several decades. Changes in the implant-tissue interface may precede performance problems. Tools to identify and characterize such changes using existing clinical measures would be highly valuable. Modern cochlear implant (CI) systems allow easy and regular measurements of electrode impedance (EI). This measure is routinely performed as a hardware integrity test, but it also allows a level of insight into the immune-mediated response to the implant, which is associated with performance outcomes. This study is a 5-year retrospective investigation of MED-EL CI users at the University of Southampton Auditory Implant Service including 176 adult ears (18-91) and 74 pediatric ears (1-17). The trend in EI in adults showed a decrease at apical electrodes. An increase was seen at the basal electrodes which are closest to the surgery site. The trend in the pediatric cohort was increasing EI over time for nearly all electrode positions, although this group showed greater variability and had a smaller sample size. We applied an outlier-labeling rule to statistically identify individuals that exhibit raised impedance. This highlighted 14 adult ears (8%) and 3 pediatric ears (5%) with impedance levels that deviated from the group distribution. The slow development of EI suggests intra-cochlear fibrosis and/or osteogenesis as the underlying mechanism. The usual clinical intervention for extreme impedance readings is to deactivate the relevant electrode. Our findings highlight some interesting clinical contradictions: some cases with raised (but not extreme) impedance had not prompted an electrode deactivation; and many cases of electrode deactivation had been informed by subjective patient reports. This emphasizes the need for improved objective evidence to inform electrode deactivations in borderline cases, for which our outlier-labeling approach is a promising candidate. A data extraction and analysis protocol that allows ongoing and automated statistical analysis of routinely collected data could benefit both the CI and wider neuroprosthetics communities. Our approach provides new tools to inform practice and to improve the function and longevity of neuroprosthetic devices.
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Affiliation(s)
- Alan P. Sanderson
- Institute of Sound and Vibration Research, Faculty of Engineering and the Environment, University of Southampton, Southampton, United Kingdom
| | - Edward T. F. Rogers
- Institute for Life Sciences and Optoelectronics Research Centre, University of Southampton, Southampton, United Kingdom
| | - Carl A. Verschuur
- Auditory Implant Service, Faculty of Engineering and the Environment, University of Southampton, Southampton, United Kingdom
| | - Tracey A. Newman
- Clinical Neurosciences, Institute for Life Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
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16
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Mesnildrey Q, Macherey O, Herzog P, Venail F. Impedance measures for a better understanding of the electrical stimulation of the inner ear. J Neural Eng 2018; 16:016023. [PMID: 30523898 DOI: 10.1088/1741-2552/aaecff] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The performance of cochlear implant (CI) listeners is limited by several factors among which the lack of spatial selectivity of the electrical stimulation. Recently, many studies have explored the use of multipolar strategies where several electrodes are stimulated simultaneously to focus the electrical field in a restricted region of the cochlea. OBJECTIVE These strategies are based on several assumptions concerning the electrical properties of the inner ear that need validation. The first, often implicit, assumption is that the medium is purely resistive and that the current waveforms produced by several electrodes sum linearly. The second assumption relates to the estimation of the contribution of each electrode to the overall electrical field. These individual contributions are usually obtained by stimulating each electrode and measuring the resulting voltage with the other inactive electrodes (i.e. the impedance matrix). However, measuring the voltage on active electrodes (i.e. the diagonal of the matrix) is not straightforward because of the polarization of the electrode-fluid interface. In existing multipolar strategies, the diagonal terms of the matrix are therefore inferred using linear extrapolation from measurements made at neighboring electrodes. APPROACH In experiment 1, several impedance measurements were carried out in vitro and in eight CI users using sinusoidal and pulsatile waveforms to test the resistivity and linearity hypotheses. In experiment 2, we used an equivalent electrical model including a constant phase element in order to isolate the polarization component of the contact impedance. MAIN RESULTS In experiment 1, high-resolution voltage recordings (1.1 MHz sampling) showed the resistivity assumption to be valid at 46.4 kHz, the highest frequency tested. However, these measures also revealed the presence of parasitic capacitive effects at high frequency that could be deleterious to multipolar strategies. Experiment 2 showed that the electrical model provides a better account of the high-resolution impedance measurements than previous approaches in the CI field that used resistor-capacitance circuit models. SIGNIFICANCE These results validate the main hypotheses underlying the use of multipolar stimulation but also suggest possible modifications to their implementation, including the use of an impedance model and the modification of the electrical pulse waveform.
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Affiliation(s)
- Quentin Mesnildrey
- Aix Marseille Univ., CNRS, Centrale Marseille, LMA, 4 impasse Nikola TESLA, CS 40006, F-13453, Marseille Cedex 13, France
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