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Grzybowski M, Malfeld K, Lenarz T, Scheper V, Schurzig D. Optimization of pharmacological interventions in the guinea pig animal model-a new approach to calculate the perilymph volume of the scala tympani. Front Neurosci 2023; 17:1297046. [PMID: 38161797 PMCID: PMC10754993 DOI: 10.3389/fnins.2023.1297046] [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] [Received: 09/19/2023] [Accepted: 11/29/2023] [Indexed: 01/03/2024] Open
Abstract
Objective The guinea pig serves as a well-established animal model for inner ear research, offering valuable insights into the anatomy, physiology, and therapeutic interventions of the auditory system. However, the heterogeneity of results observed in both in-vivo experiments and clinical studies poses challenges in understanding and optimizing pharmacotherapy outcomes. This heterogeneity may be due to individual differences in the size of the guinea pig cochlea and thus in the volume of the scala tympani (ST), which can lead to different drug concentrations in the ST, a fact that has been largely overlooked thus far. To address this issue, we aimed to develop an approach for calculating the individual volume of perilymph within the ST before and after cochlear implant insertion. Method In this study, high-resolution μCT images of a total of n = 42 guinea pig temporal bones were used to determine the volume of the ST. We compared fresh, frozen, and fixed tissues from both colored and albino strains to evaluate the potential influence of tissue condition and strain on the results. Results Our findings demonstrate a variability in mean ST volume with a relative standard deviation (RSD) of 14.7%, comparable to studies conducted with humans (range RSD: 5 to 20%). This indicates that the guinea pig cochlea exhibits similar variability to that of the human cochlea. Consequently, it is crucial to consider this variability when designing and conducting studies utilizing the guinea pig as an animal model. Furthermore, we successfully developed a tool capable of estimating ST volume without the need for manual segmentation, employing two geometric parameters, basal diameter (A) and width (B) of the cochlea, corresponding to the cochlear footprint. The tool is available for free download and use on our website. Conclusion This novel approach provides researchers with a valuable tool to calculate individual ST volume in guinea pigs, enabling more precise dosing strategies and optimization of drug concentrations for pharmacotherapy studies. Moreover, our study underscores the importance of acknowledging and accounting for inter-individual variability in animal models to enhance the translational relevance and applicability of research outcomes in the field of inner ear investigations.
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Affiliation(s)
- Marleen Grzybowski
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- German Hearing Center Hannover, Hannover Medical School, Hannover, Germany
| | - Kathrin Malfeld
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- Center for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Hannover, Germany
| | - Thomas Lenarz
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- German Hearing Center Hannover, Hannover Medical School, Hannover, Germany
- Center for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Hannover, Germany
| | - Verena Scheper
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- Center for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Hannover, Germany
| | - Daniel Schurzig
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- MED-EL Research Center, Hannover, Germany
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Konrad S, Büchner A, Lenarz T, Paasche G. Impedance development after implantation of hybrid-L24 cochlear implant electrodes. Int J Audiol 2023; 62:1137-1144. [PMID: 36193989 DOI: 10.1080/14992027.2022.2125914] [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: 11/12/2020] [Accepted: 09/13/2022] [Indexed: 11/05/2022]
Abstract
OBJECTIVE Shorter and thinner electrodes were developed for preserving residual hearing after cochlear implantation by minimising trauma. As trauma is regarded as one of the causes of fibrous tissue formation after implantation, and increase in impedance is considered to be connected to fibrous tissue formation, the aim of the current study was to evaluate impedance development after implantation of Hybrid-L electrodes. DESIGN Impedance values were retrospectively collected from our clinical database and evaluated for all active contacts and basal, middle and apical contacts separately for up to 10 years. STUDY SAMPLES All 137 adult patients received a Hybrid-L electrode and had to be implanted for at least 1 year. RESULTS On average impedances increased to 13 kOhm before first fitting and dropped to 5-7 kOhm under electrical stimulation with lower values measured on apical contacts. Mean values remained stable over years, but variability increased. Values before first fitting were independent of age at implantation whereas lower values were found later in patients of higher age at implantation. CONCLUSION Despite smaller contacts, impedance values after start of electrical stimulation were comparable to published values of Contour electrodes. This might suggest less tissue growth with the Hybrid-L electrode array.
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Affiliation(s)
- Simon Konrad
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Andreas Büchner
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
- Hearing4all Cluster of Excellence, Hannover Medical School, Hannover, Germany
| | - Thomas Lenarz
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
- Hearing4all Cluster of Excellence, Hannover Medical School, Hannover, Germany
| | - Gerrit Paasche
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
- Hearing4all Cluster of Excellence, Hannover Medical School, Hannover, Germany
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Tawk K, Goshtasbi K, Frank M, Martin EC, Abouzari M, Djalilian HR. Triamcinolone Injection for Cochlear Implant Magnet Adherence Issues. Otol Neurotol 2023; 44:e572-e576. [PMID: 37550870 PMCID: PMC10529445 DOI: 10.1097/mao.0000000000003974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/09/2023]
Abstract
OBJECTIVES To evaluate the effectiveness of triamcinolone injections in treating external magnet displacement in cochlear implant (CI) patients with adhesions problems of their processor. PATIENTS We present seven CI patients with magnet adhesion issues who presented to our tertiary care neurotology clinic. None of the patients had a history of head trauma, postimplant MRI, or surgery in the head and neck other than the cochlear implantation. INTERVENTION Triamcinolone 40 mg/mL injected subcutaneously at the CI magnet site. MAIN OUTCOME MEASURE Reduction of scalp thickness and successful magnet retention. RESULTS Our cohort consisted of seven patients (eight implant sites) of which five were overweight or obese. The temporoparietal scalp thickness measured on preoperative CT scans varied between 8.4 and 15.9 mm. Initial conservative measures such as hair shaving at the magnet site, using a headband, and increasing magnet strength failed in all patients. After receiving triamcinolone injections at the CI receiver site, six out of seven patients (seven out of eight CI sites) were able to use their processor again without the need for a headband for an average of 9.55 hours/day. The average number of injections required for each patient was 2.57 (SD = 2.18), median (range) = 1 (1-7). One patient required a flap thinning surgery but showed no improvement even after flap thinning. None of the patients showed skin irritation, breakdown, ulceration, necrosis, or magnet exposure during follow-up period. CONCLUSIONS The significant improvement in CI retention shows that triamcinolone injections are effective in making the subcutaneous tissue thinner and allowing magnet retention.
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Affiliation(s)
- Karen Tawk
- Department of Otolaryngology–Head and Neck Surgery, University of California, Irvine, USA
| | - Khodayar Goshtasbi
- Department of Otolaryngology–Head and Neck Surgery, University of California, Irvine, USA
| | - Madelyn Frank
- Department of Otolaryngology–Head and Neck Surgery, University of California, Irvine, USA
| | - Elaine C. Martin
- Department of Otolaryngology–Head and Neck Surgery, University of California, Irvine, USA
| | - Mehdi Abouzari
- Department of Otolaryngology–Head and Neck Surgery, University of California, Irvine, USA
| | - Hamid R. Djalilian
- Department of Otolaryngology–Head and Neck Surgery, University of California, Irvine, USA
- Department of Biomedical Engineering, University of California, Irvine, USA
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Eftekharian A, Khajavi M, Moghadam S, Eftekharian K, Azadeh Ranjbar L, Rezaei A. Comparison Between the Effect of Intra-Scalar Methylprednisolone and Sodium Hyaluronate in Impedance and Electrically Evoked Compound Action Potentials in Cochlear Implant Patients. Indian J Otolaryngol Head Neck Surg 2023; 75:285-290. [PMID: 37206779 PMCID: PMC10188670 DOI: 10.1007/s12070-022-03429-y] [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: 06/01/2022] [Accepted: 12/18/2022] [Indexed: 01/01/2023] Open
Abstract
To evaluate and compare the effect of intra-scalar methylprednisolone and sodium hyaluronate on cochlear implants' impedance and electrically evoked compound action potentials thresholds. In a prospective randomized clinical trial, 103 children with pre-lingual hearing loss candidates for cochlear implantation at a tertiary hospital were divided into three groups based on intervention. Intraoperatively, one group received intra-scalar methylprednisolone, the second sodium hyaluronate, and the third group was the control group. Impedance and electrically evoked compound action potentials (e-ECAP) thresholds on long-term follow-up were evaluated and compared in these three groups. Significant decrease in impedance and e-ECAP thresholds were observed in all groups in a 4-year follow-up. No statistically significant difference was observed among all mentioned groups. Impedance and e-ECAP thresholds decrease in the long term, and using topical intra-scalar Healon or methylprednisolone may not significantly affect these parameters.
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Affiliation(s)
- Ali Eftekharian
- Hearing Disorders Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mahdi Khajavi
- Hearing Disorders Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Soodabeh Moghadam
- Hearing Disorders Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Kourosh Eftekharian
- Hearing Disorders Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Leyla Azadeh Ranjbar
- Hearing Disorders Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Alireza Rezaei
- Hearing Disorders Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Meghanadh KR, Saxena U, Kumar SBR, Chacko G, N V, S S, Mehta G. Electrode impedances in children with cochlear implants: Comparison between intra-operative Switch ON and post-operative Switch ON. Cochlear Implants Int 2023; 24:65-72. [PMID: 37354550 DOI: 10.1080/14670100.2023.2172827] [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: 02/24/2023]
Abstract
INTRODUCTION Intra-operative Switch ON (IOSO) is a novel clinical approach of activating the cochlear implant during the surgery adopted at our cochlear implantation center.We compared the electrode impedances in two conditions of Switch ON of cochlear implants; IOSO and post-operative Switch ON (POSO, 21st day of surgery). METHODS Electrode impedances of 185 cochlear implants, 93 of whom received IOSO and 92 POSO, recorded over 10 years were analyzed retrospectively. RESULTS Electrode impedances of IOSO group were significantly lower than POSO group at Switch ON and 3rd, 6th, 9th, and 12th months post cochlear implantation. In IOSO group, 3rd month's electrode impedances were high when compared to electrode impedances at Switch ON. Beyond the 3rd months, electrode impedance remained unchanged. In POSO group, there were no significant differences in electrode impedances between any measurement schedule. CONCLUSIONS To our knowledge, this is the first study to investigate in detail the electrode impedances of the two above-said conditions of Switch ON in the process of cochlear implantation. This study concludes that timing of CI Switch ON has a significant effect on the electrode impedances. These results may affect the choice of cochlear implant Switch ON timing.
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Affiliation(s)
- K R Meghanadh
- Department of ENT, MAA ENT Hospitals, Hyderabad, Telangana, India
| | - Udit Saxena
- Department of ENT, MAA ENT Hospitals, Hyderabad, Telangana, India
- Department of Audiology, MAA Institute of Speech & Hearing, Hyderabad, Telangana, India
- Audiology and Speech-Language Pathology College, GMERS Medical College and Civil Hospital, Ahmedabad, Gujarat, India
| | - S B Rathna Kumar
- Department of Audiology, AYJNISHD, Mumbai, Maharashtra, India
- Department of Applied Linguistics, University of Hyderabad, Hyderabad, Telangana, India
| | - Gish Chacko
- Department of ENT, MAA ENT Hospitals, Hyderabad, Telangana, India
- Department of Audiology, MAA Institute of Speech & Hearing, Hyderabad, Telangana, India
| | - Vikas N
- Department of Audiology, MAA Institute of Speech & Hearing, Hyderabad, Telangana, India
| | - Sandhra S
- Department of Audiology, MAA Institute of Speech & Hearing, Hyderabad, Telangana, India
| | - Gunjan Mehta
- Audiology and Speech-Language Pathology College, GMERS Medical College and Civil Hospital, Ahmedabad, Gujarat, India
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Buswinka CJ, Colesa DJ, Swiderski DL, Raphael Y, Pfingst BE. Components of impedance in a cochlear implant animal model with TGFβ1-accelerated fibrosis. Hear Res 2022; 426:108638. [PMID: 36368194 PMCID: PMC10794021 DOI: 10.1016/j.heares.2022.108638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 09/21/2022] [Accepted: 10/18/2022] [Indexed: 11/04/2022]
Abstract
Outcomes of cochlear implantation are likely influenced by the biological state of the cochlea. Fibrosis is a pathological change frequently seen in implanted ears. The goal of this work was to investigate the relationship between fibrosis and impedance. To that end, we employed an animal model of extensive fibrosis and tested whether aspects of impedance differed from controls. Specifically, an adenovirus with a TGF-β1 gene insert (Ad.TGF-β1) was injected into guinea pig scala tympani to elicit rapid onset fibrosis and investigate the relation between fibrosis and impedance. We found a significant correlation between treatment and rate of impedance increase. A physical circuit model of impedance was used to separate the effect of fibrosis from other confounding factors. Supported by preliminary, yet nonconclusive, electron microscopy data, this modeling suggested that deposits on the electrode surface are an important contributor to impedance change over time.
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Affiliation(s)
- Christopher J Buswinka
- Eaton-Peabody Laboratories, Mass Eye and Ear Hospital and Harvard Medical School, Boston MA 02114.
| | - Deborah J Colesa
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Donald L Swiderski
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Yehoash Raphael
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Bryan E Pfingst
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI, 48109, USA
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7
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Biological Response Dynamics to Cochlear Implantation: Modeling and Modulating the Electrode–Tissue Interface. Ear Hear 2022; 43:1687-1697. [DOI: 10.1097/aud.0000000000001236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Leblans M, Sismono F, Vanpoucke F, van Dinther J, Lerut B, Kuhweide R, Offeciers E, Zarowski A. Novel Impedance Measures as Biomarker for Intracochlear Fibrosis. Hear Res 2022; 426:108563. [DOI: 10.1016/j.heares.2022.108563] [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: 10/29/2021] [Revised: 04/05/2022] [Accepted: 06/15/2022] [Indexed: 11/04/2022]
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Parys QA, Van Bulck P, Loos E, Verhaert N. Inner Ear Pharmacotherapy for Residual Hearing Preservation in Cochlear Implant Surgery: A Systematic Review. Biomolecules 2022; 12:biom12040529. [PMID: 35454118 PMCID: PMC9032072 DOI: 10.3390/biom12040529] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 03/25/2022] [Accepted: 03/28/2022] [Indexed: 02/05/2023] Open
Abstract
Cochlear implantation initiates an inflammatory cascade in which both acute insertion trauma and chronic foreign body reaction lead to intracochlear fibrosis and loss of residual hearing. Several strategies have been proposed to attenuate the local reactive process after implantation, including intracochlear drug delivery. The present study gives an overview of what is being investigated in the field of inner ear therapeutics and cochlear implant surgery. The aim is to evaluate its potential benefit in clinical practice. A systematic search was conducted in PubMed, Embase, and Cochrane Library databases identifying comparative prospective studies examining the effect of direct inner ear drug application on mechanical cochlear trauma. Both animal and human studies were considered and all studies were assessed for quality according to the validated risk of bias tools. Intracochlear administration of drugs is a feasible method to reduce the local inflammatory reaction following cochlear implantation. In animal studies, corticosteroid use had a significant effect on outcome measures including auditory brainstem response, impedance, and histological changes. This effect was, however, only durable with prolonged drug delivery. Significant differences in outcome were predominantly seen in studies where the cochlear damage was extensive. Six additional reports assessing non-steroidal agents were found. Overall, evidence of anti-inflammatory effects in humans is still scarce.
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Affiliation(s)
- Quentin-Alexandre Parys
- Department of Otorhinolaryngology-Head and Neck Surgery, University Hospitals Leuven, 3000 Leuven, Belgium; (Q.-A.P.); (P.V.B.); (E.L.)
| | - Pauline Van Bulck
- Department of Otorhinolaryngology-Head and Neck Surgery, University Hospitals Leuven, 3000 Leuven, Belgium; (Q.-A.P.); (P.V.B.); (E.L.)
| | - Elke Loos
- Department of Otorhinolaryngology-Head and Neck Surgery, University Hospitals Leuven, 3000 Leuven, Belgium; (Q.-A.P.); (P.V.B.); (E.L.)
- Department of Neurosciences, Research Group Experimental Oto-Rhino-Laryngology (ExpORL), KU Leuven, University of Leuven, 3000 Leuven, Belgium
| | - Nicolas Verhaert
- Department of Otorhinolaryngology-Head and Neck Surgery, University Hospitals Leuven, 3000 Leuven, Belgium; (Q.-A.P.); (P.V.B.); (E.L.)
- Department of Neurosciences, Research Group Experimental Oto-Rhino-Laryngology (ExpORL), KU Leuven, University of Leuven, 3000 Leuven, Belgium
- Correspondence:
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Tejani VD, Yang H, Kim JS, Hernandez H, Oleson JJ, Hansen MR, Gantz BJ, Abbas PJ, Brown CJ. Access and Polarization Electrode Impedance Changes in Electric-Acoustic Stimulation Cochlear Implant Users with Delayed Loss of Acoustic Hearing. J Assoc Res Otolaryngol 2022; 23:95-118. [PMID: 34686938 PMCID: PMC8782980 DOI: 10.1007/s10162-021-00809-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 07/25/2021] [Indexed: 02/03/2023] Open
Abstract
Acoustic hearing can be preserved after cochlear implant (CI) surgery, allowing for combined electric-acoustic stimulation (EAS) and superior speech understanding compared to electric-only hearing. Among patients who initially retain useful acoustic hearing, 30-40 % experience a delayed hearing loss that occurs 3 or more months after CI activation. Increases in electrode impedances have been associated with delayed loss of residual acoustic hearing, suggesting a possible role of intracochlear inflammation/fibrosis as reported by Scheperle et al. (Hear Res 350:45-57, 2017) and Shaul et al. (Otol Neurotol 40(5):e518-e526, 2019). These studies measured only total impedance. Total impedance consists of a composite of access resistance, which reflects resistance of the intracochlear environment, and polarization impedance, which reflects resistive and capacitive properties of the electrode-electrolyte interface as described by Dymond (IEEE Trans Biomed Eng 23(4):274-280, 1976) and Tykocinski et al. (Otol Neurotol 26(5):948-956, 2005). To explore the role of access and polarization impedance components in loss of residual acoustic hearing, these measures were collected from Nucleus EAS CI users with stable acoustic hearing and subsequent precipitous loss of hearing. For the hearing loss group, total impedance and access resistance increased over time while polarization impedance remained stable. For the stable hearing group, total impedance and access resistance were stable while polarization impedance declined. Increased access resistance rather than polarization impedance appears to drive the increase in total impedances seen with loss of hearing. Moreover, access resistance has been correlated with intracochlear fibrosis/inflammation in animal studies as observed by Xu et al. (Hear Res 105(1-2):1-29, 1997) and Tykocinski et al. (Hear Res 159(1-2):53-68, 2001). These findings thus support intracochlear inflammation as one contributor to loss of acoustic hearing in our EAS CI population.
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Affiliation(s)
- Viral D. Tejani
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA USA ,Department of Communication Sciences and Disorders, University of Iowa, Iowa City, IA USA
| | - Hyejin Yang
- Department of Biomedical Engineering, University of Ulsan, Ulsan, South Korea
| | - Jeong-Seo Kim
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA USA ,Department of Communication Sciences and Disorders, University of Iowa, Iowa City, IA USA
| | - Helin Hernandez
- Department of Biostatistics, University of Iowa, Iowa City, IA USA
| | - Jacob J. Oleson
- Department of Biostatistics, University of Iowa, Iowa City, IA USA
| | - Marlan R. Hansen
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA USA ,Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, IA USA ,Department of Molecular Physiology and Biophysics, University of Iowa Hospitals and Clinics, Iowa City, IA USA
| | - Bruce J. Gantz
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA USA ,Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, IA USA
| | - Paul J. Abbas
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA USA ,Department of Communication Sciences and Disorders, University of Iowa, Iowa City, IA USA
| | - Carolyn J. Brown
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA USA ,Department of Communication Sciences and Disorders, University of Iowa, Iowa City, IA USA
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Danielian A, Ishiyama G, Lopez IA, Ishiyama A. Predictors of Fibrotic and Bone Tissue Formation With 3-D Reconstructions of Post-implantation Human Temporal Bones. Otol Neurotol 2021; 42:e942-e948. [PMID: 33710156 PMCID: PMC8282738 DOI: 10.1097/mao.0000000000003106] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
HYPOTHESIS Years of implantation, surgical insertion approach, and electrode length will impact the volume of new tissue formation secondary to cochlear implantation. BACKGROUND New tissue formation, fibrosis, and osteoneogenesis after cochlear implantation have been implicated in increasing impedance and affecting performance of the cochlear implant. METHODS 3-D reconstructions of 15 archival human temporal bones from patients with a history of cochlear implantation (CI) were generated from H&E histopathologic slides to study factors which affect volume of tissue formation. RESULTS Years of implantation was a predictor of osteoneogenesis (r = 0.638, p-value = 0.011) and total new tissue formation (r = 0.588, p-value = 0.021), however not of fibrosis (r = 0.235, p-value = 0.399). Median total tissue formation differed between cochleostomy and round window insertions, 25.98 and 10.34%, respectively (Mann-Whitney U = 7, p = 0.018). No correlations were found between electrode length or angular insertion depth and total new tissue (p = 0.192, p = 0.35), osteoneogenesis (p = 0.193, p = 0.27), and fibrosis (p = 0.498, p = 0.83), respectively. However, the type II error for electrode length and angular insertion depth ranged from 0.73 to 0.90, largely due to small numbers of the shorter electrodes. CONCLUSIONS With numbers of cochlear implant recipients increasing worldwide, an understanding of how to minimize intracochlear changes from implantation is important. The present study demonstrates that increasing years of implantation and inserting electrodes via a cochleostomy compared with a round window approach are associated with significantly greater degree of new tissue volume formation. While previous studies have demonstrated increased intracochlear damage in the setting of translocation with longer electrodes, length, and angular insertion depth of CI electrodes were not associated with increased tissue formation.
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Affiliation(s)
- Arman Danielian
- UCLA David Geffen School of Medicine Department of Head and Neck Surgery, Los Angeles, CA, 90095, USA
| | - Gail Ishiyama
- UCLA David Geffen School of Medicine Department of Neurology, Los Angeles, CA, 90095, USA
| | - Ivan A Lopez
- UCLA David Geffen School of Medicine Department of Head and Neck Surgery, Los Angeles, CA, 90095, USA
| | - Akira Ishiyama
- UCLA David Geffen School of Medicine Department of Head and Neck Surgery, Los Angeles, CA, 90095, USA
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12
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Comparison of electrode impedance measures between a dexamethasone-eluting and standard Cochlear™ Contour Advance® electrode in adult cochlear implant recipients. Hear Res 2020; 390:107924. [DOI: 10.1016/j.heares.2020.107924] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 02/10/2020] [Accepted: 02/13/2020] [Indexed: 11/22/2022]
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13
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Foggia MJ, Quevedo RV, Hansen MR. Intracochlear fibrosis and the foreign body response to cochlear implant biomaterials. Laryngoscope Investig Otolaryngol 2019; 4:678-683. [PMID: 31890888 PMCID: PMC6929576 DOI: 10.1002/lio2.329] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 10/30/2019] [Indexed: 12/31/2022] Open
Abstract
OBJECTIVE To report current knowledge on the topic of intracochlear fibrosis and the foreign body response following cochlear implantation (CI). METHODS A literature search was performed in PubMed to identify peer-reviewed articles. Search components included "cochlear implant," "Foreign body response (FBR)," and "fibrosis." Original studies and review articles relevant to the topic were included. RESULTS Ninety peer-reviewed articles describing the foreign body response or intracochlear fibrosis following CI were included. CONCLUSIONS Intracochlear fibrosis following CI represents a significant limiting factor for the success of CI users. Several strategies have been employed to mitigate the foreign body response within the cochlea including drug delivery systems and modifications in surgical technique and electrode design. A better understanding of the FBR has the potential to improve CI outcomes and the next generation of cochlear prostheses.
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Affiliation(s)
- Megan J. Foggia
- Department of Otolaryngology—Head & Neck SurgeryUniversity of Iowa Hospitals and ClinicsIowa CityIowa
| | - Rene Vielman Quevedo
- Department of Otolaryngology—Head & Neck SurgeryUniversity of Iowa Hospitals and ClinicsIowa CityIowa
| | - Marlan R. Hansen
- Department of Otolaryngology—Head & Neck SurgeryUniversity of Iowa Hospitals and ClinicsIowa CityIowa
- Department of NeurosurgeryUniversity of Iowa Hospitals and ClinicsIowa CityIowa
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Cochlear Implant Insertion Axis Into the Basal Turn: A Critical Factor in Electrode Array Translocation. Otol Neurotol 2019; 39:168-176. [PMID: 29194215 DOI: 10.1097/mao.0000000000001648] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
HYPOTHESIS An inappropriate insertion axis leads to intracochlear trauma during cochlear implantation (CI). BACKGROUND Few studies assessed the relationship between the insertion axis and the electrode scalar location. METHODS Preimplantation cone-beam CT (CBCT) was performed on 12 human temporal bones. In five temporal bones, an optimal insertion axis was planned, due to the impossibility to attain the ST centerline from the posterior tympanotomy, because of facial canal position. In the seven other temporal bones, an inaccurate insertion axis was intentionally planned (optimal axis+15 degrees). Automated CI array insertion according to the planned axis was performed with a motorized insertion tool driven by a navigated robot-based arm. The cochlea and basilar membrane were segmented from the preimplantation CBCT and the array segmented from the postimplantation CBCT to construct a merged final three-dimensional (3D) model. Microscopical and 3D analysis were performed to determine the intracochlear trauma at the level of each electrode. RESULTS A good agreement was observed in determining electrode position between microscopic analysis and the 3D model (Cohen's kappa k = 0.67). The angle of approach to the ST centerline was associated with the number of electrodes inserted into the ST (r = -0.65, p = 0.02, [95% CI -0.90 to -0.11] Spearman's rank correlation). CONCLUSION A 3D reconstruction model was effective in determining the array position in the cochlea scalae. Our data indicate that the angle of approach to the ST centerline is a critical factor in intracochlear trauma. Additional studies should be conducted to assess the importance of the insertion axis with other array designs.
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Christov F, Gluth MB, Lahti SJ, Ludwig S, Hans S, Holtmann LC, Lang S, Arweiler-Harbeck D. Electric compound action potentials (ECAPs) and impedances in an open and closed operative site during cochlear implantation. Cochlear Implants Int 2018; 20:23-30. [PMID: 30350745 DOI: 10.1080/14670100.2018.1534667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
INTRODUCTION In patients undergoing cochlear implantation, intraoperative measures of impedance and electrically evoked compound action potentials (ECAPs) are used to confirm device integrity and electrode array position. However, these electrophysiological parameters have been shown to decrease over time, with a small decrement observable as early as 24 h post implantation and becoming more apparent after 6 months. Whether the intraoperatively measured impedances and ECAPs recorded immediately after electrode insertion versus later in the operation or in an open versus closed operative site vary has not been documented. Such variation in measurement procedure may affect the ultimate operative outcome. PATIENTS AND METHODS Between February and October 2016, 38 patients received a cochlear implant (Cochlear®), with half receiving a CI 522 device and the other half receiving a CI 512 device. These patients were distributed into three groups. In the first (group A; n = 21), the impedance and threshold neural response telemetry (tNRT) measures were taken before (M1) and after cutaneous suture (M2), whereas in the second group (group B; n = 11) they were taken twice in the open operative site, once at the time of electrode insertion (M1) and then again 10 min later (M2). The last group (group C; n = 6) was measured only once after a 10 min waiting time before closing the operative site. RESULTS tNRTs of both group A and B were significantly higher at M1 than measured at M2. The magnitude of change in tNRT did vary significantly by group (P = .027) with group A having a bigger decrease than group B. For impedances there was evidence for a significant difference in M2 between the three groups (P = .012), with group C having significantly higher values compared to group A and B. CONCLUSION Intraoperative tNRT measures change significantly over time, including within the first 10 min of implantation. One underlying etiology of this phenomenon for tNRTs seems to be the condition of the surgical site whereas changes of impedances can be best explained by the 'electrochemical cleaning' theory associated with the first stimulation of the electrode. However, for both impedances and tNRTs there also is an important impact of time as well as of acute perioperative changes in electrical conductivity.
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Affiliation(s)
- F Christov
- a Department of Otolaryngology, Head and Neck Surgery , University Hospital Essen , Essen , Germany.,b Section of Otolaryngology-Head & Neck Surgery , University of Chicago Medicine , Illinois , USA
| | - M B Gluth
- b Section of Otolaryngology-Head & Neck Surgery , University of Chicago Medicine , Illinois , USA
| | - S J Lahti
- c Department of Medicine , Johns Hopkins University School of Medicine , Baltimore , MD , USA
| | - S Ludwig
- a Department of Otolaryngology, Head and Neck Surgery , University Hospital Essen , Essen , Germany
| | - S Hans
- a Department of Otolaryngology, Head and Neck Surgery , University Hospital Essen , Essen , Germany
| | - L C Holtmann
- a Department of Otolaryngology, Head and Neck Surgery , University Hospital Essen , Essen , Germany
| | - S Lang
- a Department of Otolaryngology, Head and Neck Surgery , University Hospital Essen , Essen , Germany
| | - D Arweiler-Harbeck
- a Department of Otolaryngology, Head and Neck Surgery , University Hospital Essen , Essen , Germany
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Cheng X, Wang B, Liu Y, Yuan Y, Shu Y, Chen B. Comparable Electrode Impedance and Speech Perception at 12 Months after Cochlear Implantation Using Round Window versus Cochleostomy: An Analysis of 40 Patients. ORL J Otorhinolaryngol Relat Spec 2018; 80:248-258. [PMID: 30121670 PMCID: PMC6381868 DOI: 10.1159/000490764] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 06/10/2018] [Accepted: 06/10/2018] [Indexed: 11/19/2022]
Abstract
OBJECTIVE The objective of this study was to examine whether cochlear implantation using the round window (RW) route versus cochleostomy achieves comparable electrode impedance and hearing results. METHODS This retrospective analysis included 40 patients receiving a cochlear implant (REZ-1): 20 using the RW approach and the remaining 20 using cochleostomy. Electrode impedance and tone, vowel, consonant, disyllable and sentence perception were measured during and after the implantation. RESULTS Electrode impedance did not differ significantly between the 2 groups at any time points [F(1, 38) = 1.84; p = 0.184]: 1.87, 5.16, 6.47 and 6.70 kΩ in the RW group versus 2.86, 5.33, 6.92 and 8.16 kΩ in the cochleostomy group at 0, 1, 3 and 12 months, respectively. There was no significant difference between the RW and cochleostomy groups for tone (77.50 vs. 80.50%; p = 0.472), vowel (77.70 vs. 78.65%; p = 0.760), consonant (75.50 vs. 78.25%; p = 0.443), disyllable (78.60 vs. 81.50%; p = 0.317) and sentence (50.90 vs. 52.50%; p = 0.684) perception at 12 months. CONCLUSION The RW approach is comparable to cochleostomy in electrode placement as reflected by impedance and function as reflected by tone, vowel, consonant, disyllable and sentence perception.
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Affiliation(s)
- Xiaoting Cheng
- Department of Otolaryngology, Head and Neck Surgery, Eye and Ear, Nose, Throat Hospital of Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Bing Wang
- Department of Otolaryngology, Head and Neck Surgery, Eye and Ear, Nose, Throat Hospital of Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Yangwenyi Liu
- Department of Otolaryngology, Head and Neck Surgery, Eye and Ear, Nose, Throat Hospital of Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Yasheng Yuan
- Department of Otolaryngology, Head and Neck Surgery, Eye and Ear, Nose, Throat Hospital of Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Yilai Shu
- Department of Otolaryngology, Head and Neck Surgery, Eye and Ear, Nose, Throat Hospital of Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Bing Chen
- Department of Otolaryngology, Head and Neck Surgery, Eye and Ear, Nose, Throat Hospital of Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
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Cochlear Implant Associated Labyrinthitis: A Previously Unrecognized Phenomenon With a Distinct Clinical and Electrophysiological Impedance Pattern. Otol Neurotol 2017; 38:e445-e450. [DOI: 10.1097/mao.0000000000001615] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Wang J, Sun J, Sun J, Chen J. Variations in electrode impedance during and after cochlear implantation: Round window versus extended round window insertions. Int J Pediatr Otorhinolaryngol 2017; 102:44-48. [PMID: 29106874 DOI: 10.1016/j.ijporl.2017.08.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 08/27/2017] [Accepted: 08/28/2017] [Indexed: 10/18/2022]
Abstract
OBJECTIVES To assess differences in intra- and postoperative electrode impedances following cochlear implantation between round window insertions (RWI) and extended round window insertions (ERWI). METHODS Fifty patients with congenital hearing loss received unilateral hearing implants (Sonata Ti100, Med-El GmbH, Innsbruck, Austria) with standard electrode arrays. The patients were divided into two groups according to the surgical technique used. Thirty-five procedures were performed with RWI (group A) and 15 with ERWI (group B). Electrode impedance was measured and analysed during the operation, and one week and one month postoperatively. RESULTS There were no statistically significant differences (i.e., P > 0.05) in electrode impedance between groups A and B intraoperatively, or at one week or one month postoperatively. Electrode impedance at one month postoperatively was higher than the intraoperative and postoperative one week values in group A (P < 0.05), with similar results in group B. CONCLUSION There was no significant difference between RWI and ERWI in operative duration or complications of cochlear implantation. Moreover, no significant differences in postoperative electrode impedance values were found between the two surgical routes.
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Affiliation(s)
- Jun Wang
- Department of Otorhinolaryngology, Head and Neck Surgery, Anhui Provincial Hospital, Anhui Medical University, No.17 Lujiang road, Hefei 230001, Anhui, China.
| | - Jiaqiang Sun
- Department of Otorhinolaryngology, Head and Neck Surgery, Anhui Provincial Hospital, Anhui Medical University, No.17 Lujiang road, Hefei 230001, Anhui, China
| | - Jingwu Sun
- Department of Otorhinolaryngology, Head and Neck Surgery, Anhui Provincial Hospital, Anhui Medical University, No.17 Lujiang road, Hefei 230001, Anhui, China.
| | - Jianwen Chen
- Department of Otorhinolaryngology, Head and Neck Surgery, Anhui Provincial Hospital, Anhui Medical University, No.17 Lujiang road, Hefei 230001, Anhui, China
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Perilymph pharmacokinetics of marker applied through a cochlear implant in guinea pigs. PLoS One 2017; 12:e0183374. [PMID: 28817653 PMCID: PMC5560723 DOI: 10.1371/journal.pone.0183374] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 08/02/2017] [Indexed: 11/26/2022] Open
Abstract
Patients undergoing cochlear implantation could benefit from a simultaneous application of drugs into the ear, helping preserve residual low-frequency hearing and afferent nerve fiber populations. One way to apply drugs is to incorporate a cannula into the implant, through which drug solution is driven. For such an approach, perilymph concentrations achieved and the distribution in the ear over time have not previously been documented. We used FITC-labeled dextran as a marker, delivering it into perilymph of guinea pigs at 10 or 100 nL/min though a cannula incorporated into a cochlear implant with the outlet in the mid basal turn. After injections of varying duration (2 hours, 1 day or 7 days) perilymph was collected from the cochlear apex using a sequential sampling technique, allowing dextran levels and gradients along scala tympani to be quantified. Data were interpreted quantitatively using computer simulations of the experiments. For injections of 2 hours duration, dextran levels were critically influenced by the presence or absence of fluid leakage at the cochleostomy site. When the cochleostomy was fluid-tight, substantially higher perilymph levels were achieved at the injection site, with concentration declining along scala tympani towards the apex. Contrary to expectations, large dextran gradients along scala tympani persisted after 24 hours of sustained injection and were still present in some animals after 7 days injection. Functional changes associated with implantation and dextran delivery, and the histological state of the implant and cannula were also documented. The persistent longitudinal gradients of dextan along the ear were not readily explained by computer simulations of the experiments based on prior pharmacokinetic data. One explanation is that inner ear pharmacokinetics are altered in the period after cochlear implantation, possibly by a permeabilization of the blood-labyrinth barrier as part of the immune response to the implant.
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O'Malley JT, Burgess BJ, Galler D, Nadol JB. Foreign Body Response to Silicone in Cochlear Implant Electrodes in the Human. Otol Neurotol 2017; 38:970-977. [PMID: 28538471 PMCID: PMC5500409 DOI: 10.1097/mao.0000000000001454] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
HYPOTHESIS Silicone as part of a cochlear implant electrode may be responsible for a foreign body response in the human. BACKGROUND Clinical evidence of a foreign body response to a cochlear implant has been reported. In a previous study, particulate material found within the fibrous sheath and within macrophages surrounding a cochlear implant has been identified as being consistent with platinum. However, to date, there has been no histologic evidence of a role for silicone in this cellular immune response. METHODS A total of 44 temporal bone specimens from 36 patients were reviewed by light microscopy for evidence of presumed platinum and/or silicone foreign bodies in an extracellular or intracellular location. Identification of cell type involved in phagocytosis of foreign body material was accomplished using CD163 immunostaining. The identity and source of the foreign body material was confirmed using energy-dispersive X-ray spectroscopy and scanning electron microscopy. RESULTS Evidence for both platinum and silicone was found in all 44 specimens. In three patients, anti-CD 163 immunostaining demonstrated phagocytized platinum and silicone foreign bodies. In five specimens, energy-dispersive X-ray spectroscopy demonstrated that the birefringent foreign bodies were consistent with silicone. Scanning electron microscopy of two electrodes removed from temporal bones demonstrated small cracks, fragmentation, and small circular defects in the silicone carrier. CONCLUSION Histologic evidence of a foreign body response to the presence of platinum and silicone in a cochlear implant has been demonstrated and may be responsible for some reported delayed failures or extrusion.
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Affiliation(s)
- Jennifer T O'Malley
- *Otopathology Laboratory, Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Boston †Department of Materials Science and Engineering, Massachusetts Institutes of Technology, Cambridge ‡Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts
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Nogueira W, Schurzig D, Büchner A, Penninger RT, Würfel W. Validation of a Cochlear Implant Patient-Specific Model of the Voltage Distribution in a Clinical Setting. Front Bioeng Biotechnol 2016; 4:84. [PMID: 27933290 PMCID: PMC5120131 DOI: 10.3389/fbioe.2016.00084] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 10/14/2016] [Indexed: 11/13/2022] Open
Abstract
Cochlear Implants (CIs) are medical implantable devices that can restore the sense of hearing in people with profound hearing loss. Clinical trials assessing speech intelligibility in CI users have found large intersubject variability. One possibility to explain the variability is the individual differences in the interface created between electrodes of the CI and the auditory nerve. In order to understand the variability, models of the voltage distribution of the electrically stimulated cochlea may be useful. With this purpose in mind, we developed a parametric model that can be adapted to each CI user based on landmarks from individual cone beam computed tomography (CBCT) scans of the cochlea before and after implantation. The conductivity values of each cochlea compartment as well as the weighting factors of different grounding modes have also been parameterized. Simulations were performed modeling the cochlea and electrode positions of 12 CI users. Three models were compared with different levels of detail: a homogeneous model (HM), a non-patient-specific model (NPSM), and a patient-specific model (PSM). The model simulations were compared with voltage distribution measurements obtained from the backward telemetry of the 12 CI users. Results show that the PSM produces the lowest error when predicting individual voltage distributions. Given a patient-specific geometry and electrode positions, we show an example on how to optimize the parameters of the model and how to couple it to an auditory nerve model. The model here presented may help to understand speech performance variability and support the development of new sound coding strategies for CIs.
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Affiliation(s)
- Waldo Nogueira
- Department of Otolaryngology, Cluster of Excellence "Hearing4all", Medical University Hannover , Hannover , Germany
| | - Daniel Schurzig
- Department of Otolaryngology, Cluster of Excellence "Hearing4all", Medical University Hannover , Hannover , Germany
| | - Andreas Büchner
- Department of Otolaryngology, Cluster of Excellence "Hearing4all", Medical University Hannover , Hannover , Germany
| | - Richard T Penninger
- Department of Otolaryngology, Cluster of Excellence "Hearing4all", Medical University Hannover , Hannover , Germany
| | - Waldemar Würfel
- Department of Otolaryngology, Cluster of Excellence "Hearing4all", Medical University Hannover , Hannover , Germany
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Hadler C, Aliuos P, Brandes G, Warnecke A, Bohlmann J, Dempwolf W, Menzel H, Lenarz T, Reuter G, Wissel K. Polymer Coatings of Cochlear Implant Electrode Surface - An Option for Improving Electrode-Nerve-Interface by Blocking Fibroblast Overgrowth. PLoS One 2016; 11:e0157710. [PMID: 27391483 PMCID: PMC4938590 DOI: 10.1371/journal.pone.0157710] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 05/03/2016] [Indexed: 11/18/2022] Open
Abstract
Overgrowth of connective tissue and scar formation induced by the electrode array insertion increase the impedance and, thus, diminish the interactions between neural probes as like cochlear implants (CI) and the target tissue. Therefore, it is of great clinical interest to modify the carrier material of the electrodes to improve the electrode nerve interface for selective cell adhesion. On one side connective tissue growth needs to be reduced to avoid electrode array encapsulation, on the other side the carrier material should not compromise the interaction with neuronal cells. The present in vitro-study qualitatively and quantitatively characterises the interaction of fibroblasts, glial cells and spiral ganglion neurons (SGN) with ultrathin poly(N,N-dimethylacrylamide) (PDMAA), poly(2-ethyloxazoline) (PEtOx) and poly([2-methacryloyloxy)ethyl]trimethylammoniumchlorid) (PMTA) films immobilised onto glass surfaces using a photoreactive anchor layer. The layer thickness and hydrophilicity of the polymer films were characterised by ellipsometric and water contact angle measurement. Moreover the topography of the surfaces was investigated using atomic force microscopy (AFM). The neuronal and non-neuronal cells were dissociated from spiral ganglions of postnatal rats and cultivated for 48 h on top of the polymer coatings. Immunocytochemical staining of neuronal and intermediary filaments revealed that glial cells predominantly attached on PMTA films, but not on PDMAA and PEtOx monolayers. Hereby, strong survival rates and neurite outgrowth were only found on PMTA, whereas PDMAA and PEtOx coatings significantly reduced the SG neuron survival and neuritogenesis. As also shown by scanning electron microscopy (SEM) SGN strongly survived and retained their differentiated phenotype only on PMTA. In conclusion, survival and neuritogenesis of SGN may be associated with the extent of the glial cell growth. Since PMTA was the only of the polar polymers used in this study bearing a cationic charge, it can be assumed that this charge favours adhesion of both glial cells and SG neurons glial cells and SGN.
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Affiliation(s)
- C. Hadler
- Institute for Technical Chemistry, University of Technology Braunschweig, Braunschweig, Germany
| | - P. Aliuos
- Department of Otorhinolaryngology, Hannover Medical School, Hannover, Germany
- Cluster of Excellence “Hearing 4 All”, Hannover, Germany
| | - G. Brandes
- Institute of Cell Biology, Center of Anatomy, Hannover Medical School, Hannover, Germany
| | - A. Warnecke
- Department of Otorhinolaryngology, Hannover Medical School, Hannover, Germany
- Cluster of Excellence “Hearing 4 All”, Hannover, Germany
| | - J. Bohlmann
- Department of Otorhinolaryngology, Hannover Medical School, Hannover, Germany
| | - W. Dempwolf
- Institute for Technical Chemistry, University of Technology Braunschweig, Braunschweig, Germany
| | - H. Menzel
- Institute for Technical Chemistry, University of Technology Braunschweig, Braunschweig, Germany
| | - T. Lenarz
- Department of Otorhinolaryngology, Hannover Medical School, Hannover, Germany
- Cluster of Excellence “Hearing 4 All”, Hannover, Germany
| | - G. Reuter
- Department of Otorhinolaryngology, Hannover Medical School, Hannover, Germany
| | - K. Wissel
- Department of Otorhinolaryngology, Hannover Medical School, Hannover, Germany
- * E-mail:
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Gu P, Jiang Y, Gao X, Huang S, Yuan Y, Wang G, Li B, Xi X, Dai P. Effects of cochlear implant surgical technique on post-operative electrode impedance. Acta Otolaryngol 2016; 136:677-81. [PMID: 27049336 DOI: 10.3109/00016489.2016.1143967] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONCLUSIONS The mCI surgical technique led to reduced impedance and minimized disturbance of the microenvironment inside the cochlea. Atraumatic surgical techniques and inflammation-reduction strategies may preserve the cochlear architecture and prevent fibrotic development. OBJECTIVES To assess the advantages of a modified minimal access technique in cochlear implantation as well as to investigate the effects of intra-operative application of inflammation reduction strategies on the intra-cochlear impedance. METHODS One hundred patients received a 31.5 mm long Med-El standard electrode array fully inserted into the cochlea and did not have surgical complications post-operation. Patients were divided into two groups according to the surgical technique that was used for implantation: 50 were in the modified minimal access cochlear implant (mCI) surgery group and 50 were in the traditional CI surgery group. Intra-cochlear impedance values were measured at initial activation (4 weeks post-operatively). Electrode impedance values were compared between the surgery groups. RESULTS Electrode impedance values were significantly lower in the mCI group than in the CI surgery group at initial activation (5.01 kOhm vs 6.10 kOhm, respectively, F = 13.761, p = 0.000). The differences between the two groups were most prominent for the electrodes located at the basal region of the cochlea.
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Bas E, Bohorquez J, Goncalves S, Perez E, Dinh CT, Garnham C, Hessler R, Eshraghi AA, Van De Water TR. Electrode array-eluted dexamethasone protects against electrode insertion trauma induced hearing and hair cell losses, damage to neural elements, increases in impedance and fibrosis: A dose response study. Hear Res 2016; 337:12-24. [DOI: 10.1016/j.heares.2016.02.003] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 12/30/2015] [Accepted: 02/11/2016] [Indexed: 12/13/2022]
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Kuthubutheen J, Smith L, Hwang E, Lin V. Preoperative steroids for hearing preservation cochlear implantation: A review. Cochlear Implants Int 2016; 17:63-74. [PMID: 26913646 DOI: 10.1080/14670100.2016.1148319] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Preoperative steroids have been shown to be beneficial in reducing the hearing loss associated with cochlear implantation. This review article discusses the mechanism of action, effects of differing routes of administration, and side effects of steroids administered to the inner ear. Studies on the role of preoperative steroids in animal and human studies are also examined and future directions for research in this area are discussed.
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Affiliation(s)
- Jafri Kuthubutheen
- a Department of Otolaryngology - Head and Neck Surgery , University of Toronto, Sunnybrook Health Sciences Centre , Ontario , Canada.,b Department of Otolaryngology - Head and Neck Surgery , School of Surgery, University of Western Australia , Perth , Australia
| | - Leah Smith
- a Department of Otolaryngology - Head and Neck Surgery , University of Toronto, Sunnybrook Health Sciences Centre , Ontario , Canada
| | - Euna Hwang
- a Department of Otolaryngology - Head and Neck Surgery , University of Toronto, Sunnybrook Health Sciences Centre , Ontario , Canada
| | - Vincent Lin
- a Department of Otolaryngology - Head and Neck Surgery , University of Toronto, Sunnybrook Health Sciences Centre , Ontario , Canada
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Impedance Changes and Fibrous Tissue Growth after Cochlear Implantation Are Correlated and Can Be Reduced Using a Dexamethasone Eluting Electrode. PLoS One 2016; 11:e0147552. [PMID: 26840740 PMCID: PMC4739581 DOI: 10.1371/journal.pone.0147552] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 01/05/2016] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND The efficiency of cochlear implants (CIs) is affected by postoperative connective tissue growth around the electrode array. This tissue formation is thought to be the cause behind post-operative increases in impedance. Dexamethasone (DEX) eluting CIs may reduce fibrous tissue growth around the electrode array subsequently moderating elevations in impedance of the electrode contacts. METHODS For this study, DEX was incorporated into the silicone of the CI electrode arrays at 1% and 10% (w/w) concentration. Electrodes prepared by the same process but without dexamethasone served as controls. All electrodes were implanted into guinea pig cochleae though the round window membrane approach. Potential additive or synergistic effects of electrical stimulation (60 minutes) were investigated by measuring impedances before and after stimulation (days 0, 7, 28, 56 and 91). Acoustically evoked auditory brainstem responses were recorded before and after CI insertion as well as on experimental days 7, 28, 56, and 91. Additionally, histology performed on epoxy embedded samples enabled measurement of the area of scala tympani occupied with fibrous tissue. RESULTS In all experimental groups, the highest levels of fibrous tissue were detected in the basal region of the cochlea in vicinity to the round window niche. Both DEX concentrations, 10% and 1% (w/w), significantly reduced fibrosis around the electrode array of the CI. Following 3 months of implantation impedance levels in both DEX-eluting groups were significantly lower compared to the control group, the 10% group producing a greater effect. The same effects were observed before and after electrical stimulation. CONCLUSION To our knowledge, this is the first study to demonstrate a correlation between the extent of new tissue growth around the electrode and impedance changes after cochlear implantation. We conclude that DEX-eluting CIs are a means to reduce this tissue reaction and improve the functional benefits of the implant by attenuating electrode impedance.
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Lee MY, Lee JH, Lee HS, Choi JJ, Jang J, Choi H, Oh SH, Jang JH. Continuous topical drug delivery using osmotic pump in animal cochlear implant model: Continuous steroid delivery is effective for hearing preservation. Acta Otolaryngol 2015; 135:791-8. [PMID: 25813859 DOI: 10.3109/00016489.2015.1030771] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
CONCLUSIONS Continuous topical drug delivery using an osmotic pump is an effective supplementary technique for hearing preservation after cochlear implantation, as demonstrated in a guinea pig model. OBJECTIVE To evaluate the effect of continuous topical steroid delivery via an osmotic pump in an animal cochlear implant model. METHODS Twenty-three guinea pigs were used for the study. The animals were divided into three groups: control group (n = 8), simple topical dexamethasone delivery group (sDEXA group, n = 7) and continuous topical dexamethasone delivery group (cDEXA, n = 8). The hearing thresholds of all animals were measured by pre-operative auditory brain stem responses (ABRs) at 2, 8, 16, 24, and 32 kHz. ABRs were re-evaluated after cochlear implantation, and the animals were sacrificed for hematoxylin and eosin staining. RESULTS The ABR threshold at 1 week post-operatively was significantly lower in the cDEXA group than in the control and sDEXA groups at most frequencies. Threshold shifts from baseline were statistically smaller in the cDEXA group than in the control and sDEXA groups at all frequencies. Histological analysis revealed decreased numbers of multi-nucleated giant cells and thinner histiocyte layers.
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Affiliation(s)
- Min Young Lee
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital , Seoul , Korea
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Smeds H, Eastwood HT, Hampson AJ, Sale P, Campbell LJ, Arhatari BD, Mansour S, O'Leary SJ. Endolymphatic hydrops is prevalent in the first weeks following cochlear implantation. Hear Res 2015; 327:48-57. [PMID: 25987505 DOI: 10.1016/j.heares.2015.04.017] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 04/02/2015] [Accepted: 04/24/2015] [Indexed: 01/15/2023]
Abstract
AIM To explore morphological or electrophysiological evidence for the presence of endolymphatic hydrops (EH) in guinea pig cochleae in the first 3 months after cochlear implantation. METHODS Dummy silastic electrodes were implanted atraumatically into the basal turn of scala tympani via a cochleostomy. Round window electrocochleography (ECochG) was undertaken prior to and after implantation. Animals survived for 1, 7, 28 or 72 days prior to a terminal experiment, when ECochG was repeated. The cochleae were imaged using micro-CT after post-fixing with osmium tetroxide to reveal the inner ear soft tissue structure. EH was assessed by visual inspection at a series of frequency specific places along the length of the cochlea, and the extent to which Reissner's membrane departed from its neutral position was quantified. Tissue response volumes were calculated. Using ECochG, the ratio of the summating potential to the action potential (SP/AP ratio) was calculated in response to frequencies between 2 and 32 kHz. RESULTS There was minimal evidence of electrode trauma from cochlear implantation on micro-CT imaging. Tissue response volumes did not change over time. EH was most prevalent 7 days after surgery in implanted ears, as determined by visual inspection. Scala media areas were increased, as expected in cases of EH, over the first month after cochlear implantation. SP/AP ratios decreased immediately after surgery, but were elevated 1 and 7 days after implantation. CONCLUSIONS EH is prevalent in the first weeks after implant surgery, even in the absence of significant electrode insertion trauma.
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Affiliation(s)
- H Smeds
- Department of Otolaryngology, University of Melbourne, 2nd Floor, Peter Howson Wing, Royal Victorian Eye and Ear Hospital, 32 Gisborne St, East Melbourne, Victoria 3002, Australia; Karolinska University Hospital, Stockholm, Sweden.
| | - H T Eastwood
- Department of Otolaryngology, University of Melbourne, 2nd Floor, Peter Howson Wing, Royal Victorian Eye and Ear Hospital, 32 Gisborne St, East Melbourne, Victoria 3002, Australia.
| | - A J Hampson
- Department of Otolaryngology, University of Melbourne, 2nd Floor, Peter Howson Wing, Royal Victorian Eye and Ear Hospital, 32 Gisborne St, East Melbourne, Victoria 3002, Australia.
| | - P Sale
- Department of Otolaryngology, University of Melbourne, 2nd Floor, Peter Howson Wing, Royal Victorian Eye and Ear Hospital, 32 Gisborne St, East Melbourne, Victoria 3002, Australia.
| | - L J Campbell
- Department of Otolaryngology, University of Melbourne, 2nd Floor, Peter Howson Wing, Royal Victorian Eye and Ear Hospital, 32 Gisborne St, East Melbourne, Victoria 3002, Australia.
| | - B D Arhatari
- ARC Centre of Excellence for Advanced Molecular Imaging, Department of Physics, La Trobe University, Victoria 3086, Australia.
| | - S Mansour
- Department of Otolaryngology, University of Melbourne, 2nd Floor, Peter Howson Wing, Royal Victorian Eye and Ear Hospital, 32 Gisborne St, East Melbourne, Victoria 3002, Australia.
| | - S J O'Leary
- Department of Otolaryngology, University of Melbourne, 2nd Floor, Peter Howson Wing, Royal Victorian Eye and Ear Hospital, 32 Gisborne St, East Melbourne, Victoria 3002, Australia.
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Liu Y, Jolly C, Braun S, Janssen T, Scherer E, Steinhoff J, Ebenhoch H, Lohner A, Stark T, Kiefer J. Effects of a dexamethasone-releasing implant on cochleae: A functional, morphological and pharmacokinetic study. Hear Res 2015; 327:89-101. [PMID: 25987502 DOI: 10.1016/j.heares.2015.04.019] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 04/22/2015] [Accepted: 04/24/2015] [Indexed: 01/12/2023]
Abstract
AIM This study evaluated the impact of a dexamethasone-releasing silicone implant on hearing function preservation, cochlear morphology and perilymph pharmacokinetics after cochlear implantation. METHODS Guinea pigs were implanted unilaterally with silicone rods containing either 2% dexamethasone (DEXA group, n = 18) or no dexamethasone (control group, n = 17). Auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAEs) were measured preoperatively and over 6 months postoperatively. Cochlear histology using standard hematoxylin and eosin (H&E) staining and tumor necrosis factor (TNF)-alpha staining was performed 1 month postoperatively. Twenty-two guinea pigs were involved in the pharmacokinetic study, and real-time drug concentrations in perilymph were investigated using high-performance liquid chromatography (HPLC). The Mann-Whitney U test (1-tailed) was used for statistical analyses. RESULTS ABR and DPOAE testing demonstrated decreased hearing function immediately postoperatively followed by a progressive hearing loss within the first day postoperatively. There was almost no observable hearing improvement in the control group from 1 week to 6 months postoperatively, but hearing levels in the DEXA group improved gradually from 1 week to 12 weeks. Hearing loss in the DEXA and control group was 5.0 ± 3.4 dB and 21.7 ± 5.3 dB, respectively at a 16-kHz stimulus frequency 6 months postoperatively. The difference in threshold shifts was present throughout all measured frequencies, and it was significant at 4-24 kHz. The morphological study revealed new fibrosis formation in the scala tympani, which encapsulated the implanted electrode. TNF-alpha positive staining in the cochleae of the DEXA group was less evident than the control group. The pharmacokinetic study revealed a peak perilymph concentration 30 min postoperatively and sustained dexamethasone release at least 1 week postoperatively. CONCLUSION Cochlear implants that incorporate dexamethasone can release drug chronically in the inner ear and induce significant long-term recovery and preservation of auditory function after implantation.
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Affiliation(s)
- Ya Liu
- Department of Otolaryngology-Head and Neck Surgery, Beijing Naval General Hospital, Beijing 100048, PR China
| | - Claude Jolly
- Electrode Research Section, MED-EL Medical Electronics, Innsbruck, Austria
| | | | - Thomas Janssen
- Clinic for Otorhinolaryngology, Head- and Neck Surgery, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Elias Scherer
- Clinic for Otorhinolaryngology, Head- and Neck Surgery, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Jochen Steinhoff
- Clinic for Otorhinolaryngology, Head- and Neck Surgery, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Harald Ebenhoch
- Clinic for Otorhinolaryngology, Head- and Neck Surgery, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Andrea Lohner
- Clinic for Otorhinolaryngology, Head- and Neck Surgery, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Thomas Stark
- Clinic for Otorhinolaryngology, Head- and Neck Surgery, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Jan Kiefer
- HNO-Zentrum Neupfarrplatz, 12/II, 93047 Regensburg, Germany.
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Ramos BF, Tsuji RK, Bento RF, Goffi-Gomez MVS, Ramos HF, Samuel PA, Brito R. Hearing preservation using topical dexamethasone alone and associated with hyaluronic acid in cochlear implantation. Acta Otolaryngol 2015; 135:473-7. [PMID: 25719419 DOI: 10.3109/00016489.2014.995831] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
CONCLUSION Topical dexamethasone associated with hyaluronic acid in cochlear implant surgery demonstrated a statistically significant difference in the preservation of low-frequency thresholds when compared with topical dexamethasone alone and a control group. Topical dexamethasone alone was not superior in hearing preservation when compared to the control group. OBJECTIVE To compare the effects of topical dexamethasone alone and associated with hyaluronic acid intraoperatively in hearing preservation in cochlear implantation. METHODS Eighteen severely to profoundly hearing-impaired adult patients with measurable hearing were divided into three groups preoperatively: cochlear implantation as a control group (group 1), cochlear implantation using topical dexamethasone intraoperatively (group 2), and cochlear implantation using topical dexamethasone associated with hyaluronic acid intraoperatively (group 3). Preimplant and postimplant low-frequency pure-tone averages (PTAs) were calculated from unaided audiograms at 125, 250, and 500 Hz. RESULTS The mean changes in the low-frequency PTA comparing postoperative against preoperative thresholds were 28.03 ± 6.77 dB in group 1, 30 ± 14.53 dB in group 2, and 7.23 ± 6.12 dB in group 3. There was statistical difference when comparing group 3 with groups 1 and 2 using one-way ANOVA (p = 0.002) followed by Scheffé post hoc test.
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Affiliation(s)
- Bernardo Faria Ramos
- Department of Otolaryngology, University of São Paulo School of Medicine , São Paulo , Brazil
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Stathopoulos D, Chambers S, Adams L, Robins-Browne R, Miller C, Enke YL, Wei BPC, O'Leary S, Cowan R, Newbold C. Meningitis and a safe dexamethasone-eluting intracochlear electrode array. Cochlear Implants Int 2014; 16:201-7. [DOI: 10.1179/1754762814y.0000000099] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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Kikkawa YS, Nakagawa T, Ying L, Tabata Y, Tsubouchi H, Ido A, Ito J. Growth factor-eluting cochlear implant electrode: impact on residual auditory function, insertional trauma, and fibrosis. J Transl Med 2014; 12:280. [PMID: 25280483 PMCID: PMC4189752 DOI: 10.1186/s12967-014-0280-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 09/24/2014] [Indexed: 11/10/2022] Open
Abstract
Background A cochlear implant (CI) is an artificial hearing device that can replace a damaged cochlea. The present study examined the use of growth factor-eluting gelatin hydrogel coatings on the electrodes to minimize inner ear trauma during electrode insertion. Insulin-like growth factor 1 (IGF1) and/or hepatocyte growth factor (HGF) were chosen as the agents to be administered. Methods Silicone CI electrode analogs were prepared and coated with gelatin hydrogels. Adsorption/release profile of the hydrogel was measured using 125I-radiolabeled IGF. Hydrogel-coated electrodes were absorbed with IGF1, HGF, IGF1 plus HGF, or saline (control) and implanted into the basal turns of guinea pig cochleae (n = 5). Auditory sensitivity was determined pre-operatively, immediately after, and 3, 7, 14, 21, and 28 days post-operatively by using auditory brainstem response (ABR; 4–16 kHz). In addition, histological analysis was performed and auditory hair cell (HC) survival, spiral ganglion neuron (SGN) densities, and fibrous tissue thickness were measured. Results Compared to non-coated arrays, hydrogel-coated electrodes adsorbed significantly greater amounts of IGF1 and continuously released it for 48 h. Residual hearing measured by ABR thresholds after surgery were elevated by 50–70 dB in all of the electrode-implanted animals, and was maximal immediately after operation. Thresholds were less elevated after hydrogel treatment, and the hearing protection improved when IGF1 or HGF was applied. Histopathologically, hair cell survival, spiral ganglion cell survival, and fibrous tissue thickness were not different between the experimental groups. No serious adverse events were observed during the 4-week observation period. Conclusions Our findings provide the first evidence that hydrogel-coated, growth factor-releasing CI electrodes could attenuate insertional trauma and promote recovery from it, suggesting that this combination might be a new drug delivery strategy not only in cochlear implantation but also in treating clinical conditions characterized by inner ear damage.
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Impedance, neural response telemetry, and speech perception outcomes after reimplantation of cochlear implants in children. Otol Neurotol 2014; 35:1385-93. [PMID: 24662639 DOI: 10.1097/mao.0000000000000362] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To compare mean impedance levels, neural response telemetry (NRT), and auditory perception after initial and explant-reimplant pediatric cochlear implants. STUDY DESIGN Retrospective case review. SETTING Tertiary referral hospital and cochlear implant program. PATIENTS Children 0 to 16 years inclusive who have undergone explant-reimplant of their cochlear implant. INTERVENTION Impedance levels, NRT, and speech perception performance. MAIN OUTCOME MEASURES Impedance, NRT, and auditory perception at switch on, 3 months, 12 months, 3 years, and 5 years after initial cochlear implant and reimplantation. RESULTS The explant-reimplant group receiving Cochlear contour array had significantly (p < 0.001) raised impedance at switch on, 3 months, 12 months, and 3 years, compared with their initial implant. The explant-reimplant group receiving Cochlear straight array had marginally significant (p = 0.045) raised impedance at switch on, 3 months, 12 months, and 3 and 5 years. Infection was associated with greater increases in impedance in the reimplant Contour group. NRT was increased in the explant-reimplant group but not significantly (p = 0.06). Auditory perception returned to preexplant levels within 6 months in 61% of children. CONCLUSION Impedance is higher after explant-reimplant and remains increased for years after explant-reimplant with Cochlear contour and to a lesser degree the straight array device.
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Stathopoulos D, Chambers S, Enke YL, Timbol G, Risi F, Miller C, Cowan R, Newbold C. Development of a safe dexamethasone-eluting electrode array for cochlear implantation. Cochlear Implants Int 2014; 15:254-63. [PMID: 24621150 DOI: 10.1179/1754762813y.0000000054] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
OBJECTIVES Cochlear implantation can result in trauma leading to increased tissue response and loss of residual hearing. A single intratympanic application of the corticosteroid dexamethasone is sometimes used clinically during surgery to combat the potential effect of trauma on residual hearing. This project looked at the safety and efficacy of dexamethasone eluted from an intracochlear array in vivo. METHODS Three trials were conducted using normal hearing adult guinea pigs implanted with successive iterations of dexamethasone-eluting (DX1, DX2, and DX3) or non-eluting (control) intracochlear electrode arrays. The experimental period for each animal was 90 days during which hearing tests were performed at multiple time points. RESULTS There was no significant difference between matched control array and dexamethasone array groups in terms of spiral ganglion neuron density, organ of Corti condition, or fibrosis and ossification. A cochleostomy seal was present in all implanted cochleae. There were no differences in the degree of hearing threshold shifts between DX1 and DX3 and their respective control arrays. Cochleae implanted with DX2 arrays showed less hearing loss and marginally better spiral ganglion neuron survival than their control array counterparts. Post-explant inspection of the DX2 and DX3 arrays revealed a difference in pore density following dexamethasone elution. CONCLUSION The dexamethasone doses used were safe in the guinea pig cochlea. Dexamethasone did not inhibit formation of a cochleostomy seal. The level of hearing protection afforded by dexamethasone eluting from an intracochlear array may depend upon the degree of elution and level of trauma inflicted.
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Newbold C, Mergen S, Richardson R, Seligman P, Millard R, Cowan R, Shepherd R. Impedance changes in chronically implanted and stimulated cochlear implant electrodes. Cochlear Implants Int 2013; 15:191-9. [PMID: 23998484 DOI: 10.1179/1754762813y.0000000050] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
OBJECTIVES Electrode impedance increases following implantation and undergoes transitory reduction with onset of electrical stimulation. The studies in this paper measured the changes in access resistance and polarization impedance in vivo before and following electrical stimulation, and recorded the time course of these changes. DESIGN Impedance measures recorded in (a) four cats following 6 months of cochlear implant use, and (b) three cochlear implant recipients with 1.5-5 years cochlear implant experience. RESULTS Both the experimental and clinical data exhibited a reduction in electrode impedance, 20 and 5% respectively, within 15-30 minutes of stimulation onset. The majority of these changes occurred through reduction in polarization impedance. Cessation of stimulation was followed by an equivalent rise in impedance measures within 6-12 hours. CONCLUSIONS Stimulus-induced reductions in impedance exhibit a rapid onset and are evident in both chronic in vivo models tested, even several years after implantation. Given the impedance changes were dominated by the polarization component, these findings suggest that the electrical stimulation altered the electrode surface rather than the bulk tissue and fluid in the cochlea.
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Jia H, Wang J, François F, Uziel A, Puel JL, Venail F. Molecular and cellular mechanisms of loss of residual hearing after cochlear implantation. Ann Otol Rhinol Laryngol 2013; 122:33-9. [PMID: 23472314 DOI: 10.1177/000348941312200107] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVES We describe the various molecular and cellular pathways that lead to early and delayed loss of residual hearing after cochlear implantation. METHODS We performed a systematic review using the Medline database with the key words cochlear implant, residual hearing, inflammation, apoptosis, and necrosis. RESULTS The mechanisms underlying the loss of residual hearing after cochlear implantation are multiple. Early hearing loss may be provoked by the surgical access to the inner ear spaces and by trauma caused by insertion of the electrode array. After the initial trauma, an acute inflammatory response promotes elevated levels of cytokines and reactive oxygen species, which in turn promote sensory cell loss by apoptosis, necrosis, and necrosis-like programmed cell death. Treatments that counteract such an inflammatory reaction, production of reactive oxygen species, and apoptosis are effective at preventing hair cell degeneration. However, delayed hearing loss appears to be a consequence of chronic inflammation with development of fibrotic tissue. The mechanisms that lead to fibrosis are poorly understood, and standard antiinflammatory drugs are insufficient for preventing its development. CONCLUSIONS Cochlear implantation is followed by an inflammatory response involving several pathways that lead to either short-term or long-term sensory hair cell degeneration. Future studies should focus on revealing the precise molecular mechanisms induced by cochlear implantation to allow the discovery of new targets for the effective prevention and treatment of loss of residual hearing.
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Affiliation(s)
- Huan Jia
- INSERM, Institute for Neurosciences of Montpellier, University Montpellier I, Montpellier, France
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Souter M, Eastwood H, Marovic P, Kel G, Wongprasartsuk S, Ryan AF, O’Leary SJ. Systemic immunity influences hearing preservation in cochlear implantation. Otol Neurotol 2012; 33:532-8. [PMID: 22470051 PMCID: PMC3897157 DOI: 10.1097/mao.0b013e31824bac44] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
HYPOTHESIS To determine whether a systemic immune response influences hearing thresholds and tissue response after cochlear implantation of hearing guinea pigs. METHODS Guinea pigs were inoculated with sterile antigen (Keyhole limpet hemocyanin) 3 weeks before cochlear implantation. Pure-tone auditory brainstem response thresholds were performed before implantation and 1 and 4 weeks later. Dexamethasone phosphate 20% was adsorbed onto a hyaluronic acid carboxymethylcellulose sponge and was applied to the round window for 30 minutes before electrode insertion. Normal saline was used for controls. Cochlear histology was performed at 4 weeks after implantation to assess the tissue response to implantation. To control for the effect of keyhole limpet hemocyanin priming, a group of unprimed animals underwent cochlear implantation with a saline-soaked pledget applied to the round window. RESULTS Keyhole limpet hemocyanin priming had no significant detrimental effect on thresholds without implantation. Thresholds were elevated after implantation across all frequencies tested (2-32 kHz) in primed animals but only at higher frequencies (4-32 kHz) in unprimed controls. In primed animals, dexamethasone treatment significantly reduced threshold shifts at 2 and 8 kHz. Keyhole limpet hemocyanin led to the more frequent observation of lymphocytes in the tissue response to the implant. CONCLUSION Systemic immune activation at the time of cochlear implantation broadened the range of frequencies experiencing elevated thresholds after implantation. Local dexamethasone provides partial protection against this hearing loss, but the degree and extent of protection are less compared to previous studies with unprimed animals.
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Affiliation(s)
- Melanie Souter
- Department of Otolaryngology, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
- Department of Otolaryngology, Christchurch Hospital, Christchurch, New Zealand
| | - Hayden Eastwood
- Department of Otolaryngology, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Paul Marovic
- Department of Otolaryngology, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
- Department of Surgery, Monash University, Clayton, Australia
| | - Gordana Kel
- Department of Otolaryngology, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Sarin Wongprasartsuk
- Department of Otolaryngology, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
- Department of Surgery, Monash University, Clayton, Australia
| | - Allen F. Ryan
- Departments of Otolaryngology and Neurosciences, University of California at San Diego
- San Diego VA Healthcare System, San Diego, California, U.S.A
| | - Stephen John O’Leary
- Department of Otolaryngology, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
- Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
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Stöver T, Lenarz T. Biomaterials in cochlear implants. GMS CURRENT TOPICS IN OTORHINOLARYNGOLOGY, HEAD AND NECK SURGERY 2011; 8:Doc10. [PMID: 22073103 PMCID: PMC3199815 DOI: 10.3205/cto000062] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The cochlear implant (CI) represents, for almost 25 years now, the gold standard in the treatment of children born deaf and for postlingually deafened adults. These devices thus constitute the greatest success story in the field of ‘neurobionic’ prostheses. Their (now routine) fitting in adults, and especially in young children and even babies, places exacting demands on these implants, particularly with regard to the biocompatibility of a CI’s surface components. Furthermore, certain parts of the implant face considerable mechanical challenges, such as the need for the electrode array to be flexible and resistant to breakage, and for the implant casing to be able to withstand external forces. As these implants are in the immediate vicinity of the middle-ear mucosa and of the junction to the perilymph of the cochlea, the risk exists – at least in principle – that bacteria may spread along the electrode array into the cochlea. The wide-ranging requirements made of the CI in terms of biocompatibility and the electrode mechanism mean that there is still further scope – despite the fact that CIs are already technically highly sophisticated – for ongoing improvements to the properties of these implants and their constituent materials, thus enhancing the effectiveness of these devices. This paper will therefore discuss fundamental material aspects of CIs as well as the potential for their future development.
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Affiliation(s)
- Timo Stöver
- Department of Otolaryngology, Goethe University Frankfurt, Frankfurt a.M., Germany
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Abstract
Delivery of medications to the inner ear has been an area of considerable growth in both the research and clinical realms during the past several decades. Systemic delivery of medication destined for treatment of the inner ear is the foundation on which newer delivery techniques have been developed. Because of systemic side effects, investigators and clinicians have begun developing and using techniques to deliver therapeutic agents locally. Alongside the now commonplace use of intratympanic gentamicin for Meniere's disease and the emerging use of intratympanic steroids for sudden sensorineural hearing loss, novel technologies, such as hydrogels and nanoparticles, are being explored. At the horizon of inner ear drug-delivery techniques, intracochlear devices that leverage recent advances in microsystems technology are being developed to apply medications directly into the inner ear. Potential uses for such devices include neurotrophic factor and steroid delivery with cochlear implantation, RNA interference technologies, and stem-cell therapy. The historical, current, and future delivery techniques and uses of drug delivery for treatment of inner ear disease serve as the basis for this review.
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The Long-Term Effects of Modified Electrode Surfaces and Intracochlear Corticosteroids on Postoperative Impedances in Cochlear Implant Patients. Otol Neurotol 2009; 30:592-8. [DOI: 10.1097/mao.0b013e3181ab8fba] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
Recent advances in cochlear implant technology have focused renewed attention on the preservation of residual hearing. The focus on preservation of residual hearing is driven by the concept of electroacoustic stimulation. This option depends on the insertion of a short cochlear implant electrode into the basal region of the cochlea while preserving native function in the apical region. The desire to preserve residual hearing has led to the development of the soft-surgery cochlear implantation technique. Here, the authors evaluate its various components. Avoiding entry of blood into the cochlea and the use of hyaluronate seem to be reasonably supported, whereas the use of topical steroids is unlikely to be beneficial. The site of entry into the cochlea, the use of contoured or straight devices, and the depth of insertion are also evaluated. The authors highlight the importance of systematic recording of outcomes and surgical events.
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Affiliation(s)
- David R Friedland
- Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, 9200 W. Wisconsin Avenue, Milwaukee, WI 53226, USA.
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James DP, Eastwood H, Richardson RT, O’Leary SJ. Effects of Round Window Dexamethasone on Residual Hearing in a Guinea Pig Model of Cochlear Implantation. Audiol Neurootol 2007; 13:86-96. [DOI: 10.1159/000111780] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2006] [Accepted: 07/27/2007] [Indexed: 12/20/2022] Open
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