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Tan E, Bester C, Collins A, Razmovski T, O'Leary S. Four-Point Impedance: A Potential Biomarker for Residual Hearing After Cochlear Implantation. Otol Neurotol 2024; 45:e315-e321. [PMID: 38478410 DOI: 10.1097/mao.0000000000004153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/29/2024]
Abstract
INTRODUCTION Preservation of residual hearing after cochlear implantation allows for electroacoustic stimulation, which leads to better music appreciation, noise localization, and speech comprehension in noisy environments. Real-time intraoperative electrocochleography (rt-ECochG) monitoring has shown promise in improving residual hearing rates. Four-point impedance (4PI) is being explored as a potential biomarker in cochlear implantation that has been associated with fibrotic tissue response, hearing loss, and dizziness. In this study, we explore whether monitoring both rt-ECochG intraoperatively and postoperative 4PI improves predictions of the preservation of residual hearing. METHODS This was a prospective cohort study. Adults with residual acoustic hearing underwent cochlear implantation with intraoperative intracochlear electrocochleography (ECochG) monitoring. The surgeon responded to a drop in ECochG signal amplitude of greater than 30% by a standardized manipulation of the electrode with the aim of restoring the ECochG. At the end of the procedure, the ECochG signal was categorized as being maintained or having dropped more than 30%. 4PI was measured on 1 day, 1 week, and 1 and 3 months after cochlear implantation. Residual hearing was measured by routine pure-tone audiogram at 3 months postoperatively. The ECochG category and 4PI impedance values were entered as factors in a multiple linear regression predicting the protection of residual hearing. RESULTS Twenty-six patients were recruited. Rt-ECochG significantly predicted residual hearing at 3 months (t test; mean difference, 37.7%; p = 0.002). Inclusion of both 1-day or 3-month 4PI in a multiple linear regression with rt-ECochG markedly improved upon correlations with residual hearing compared with the rt-ECochG-only model (rt-ECochG and 1-d 4PI model, R2 = 0.67; rt-ECochG and 3-mo 4PI model, R2 = 0.72; rt-ECochG-only model, R2 = 0.33). CONCLUSIONS Both rt-ECochG and 4PI predict preservation of residual hearing after cochlear implantation. These findings suggest that the biological response of the cochlea to implantation, as reflected in 4PI, is an important determinant of residual hearing, independent of the acute effects on hearing during implant surgery seen with rt-ECochG. We speculate that 4PI relates to inflammation 1 day after implantation and fibrosis at 3 months.
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Affiliation(s)
- Eren Tan
- The Department of Otolaryngology, The University of Melbourne
| | | | - Aaron Collins
- The Department of Otolaryngology, The University of Melbourne
| | - Tayla Razmovski
- The Department of Otolaryngology, The University of Melbourne
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Kwok BYC, Young AS, Kong JHK, Birman CS, Flanagan S, Greenberg SL, Gibson WP, Argaet EC, Fratturo L, Pogson JM, Taylor RL, Rosengren SM, Halmagyi GM, Welgampola MS. Post Cochlear Implantation Vertigo: Ictal Nystagmus and Audiovestibular Test Characteristics. Otol Neurotol 2024; 45:65-74. [PMID: 37853785 DOI: 10.1097/mao.0000000000004037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
Abstract
OBJECTIVE To investigate ictal nystagmus and audiovestibular characteristics in episodic spontaneous vertigo after cochlear implantation (CI). STUDY DESIGN Retrospective and prospective case series. PATIENTS Twenty-one CI patients with episodic spontaneous vertigo after implantation were recruited. INTERVENTIONS Patient-initiated home video-oculography recordings were performed during one or more attacks of vertigo, using miniature portable home video-glasses. To assess canal and otolith function, video head-impulse tests (vHITs) and vestibular-evoked myogenic potential tests were conducted. MAIN OUTCOME MEASURES Nystagmus slow-phase velocities (SPVs), the presence of horizontal direction-changing nystagmus, and post-CI audiovestibular tests. RESULTS Main final diagnoses were post-CI secondary endolymphatic hydrops (48%) and exacerbation of existing Ménière's disease (29%). Symptomatic patients demonstrated high-velocity horizontal ictal-nystagmus (SPV, 44.2°/s and 68.2°/s in post-CI secondary endolymphatic hydrop and Ménière's disease). Direction-changing nystagmus was observed in 80 and 75%. Two were diagnosed with presumed autoimmune inner ear disease (SPV, 6.6°/s and 172.9°/s). One patient was diagnosed with probable vestibular migraine (15.1°/s).VHIT gains were 0.80 ± 0.20 (lateral), 0.70 ± 0.17 (anterior), and 0.62 ± 0.27 (posterior) in the implanted ear, with abnormal values in 33, 35, and 35% of each canal. Bone-conducted cervical and ocular vestibular-evoked myogenic potentials were asymmetric in 52 and 29% of patients (all lateralized to the implanted ear) with mean asymmetry ratios of 51.2 and 35.7%. Reversible reduction in vHIT gain was recorded in three acutely symptomatic patients. CONCLUSION High-velocity, direction-changing nystagmus time-locked with vertigo attacks may be observed in post-CI implant vertigo and may indicate endolymphatic hydrops. Fluctuating vHIT gain may be an additional marker of a recurrent peripheral vestibulopathy.
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Affiliation(s)
| | | | | | | | - Sean Flanagan
- Department of Otolaryngology, Head and Neck, and Skull Base Surgery, St Vincent's Public Hospital, Sydney
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de Rijk SR, Boys AJ, Roberts IV, Jiang C, Garcia C, Owens RM, Bance M. Tissue-Engineered Cochlear Fibrosis Model Links Complex Impedance to Fibrosis Formation for Cochlear Implant Patients. Adv Healthc Mater 2023; 12:e2300732. [PMID: 37310792 DOI: 10.1002/adhm.202300732] [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] [Received: 03/07/2023] [Revised: 05/30/2023] [Indexed: 06/15/2023]
Abstract
Cochlear implants are a life-changing technology for those with severe sensorineural hearing loss, partially restoring hearing through direct electrical stimulation of the auditory nerve. However, they are known to elicit an immune response resulting in fibrotic tissue formation in the cochlea that is linked to residual hearing loss and suboptimal outcomes. Intracochlear fibrosis is difficult to track without postmortem histology, and no specific electrical marker for fibrosis exists. In this study, a tissue-engineered model of cochlear fibrosis is developed following implant placement to examine the electrical characteristics associated with fibrotic tissue formation around electrodes. The model is characterized using electrochemical impedance spectroscopy and an increase in the resistance and a decrease in capacitance of the tissue using a representative circuit are found. This result informs a new marker of fibrosis progression over time that is extractable from voltage waveform responses, which can be directly measured in cochlear implant patients. This marker is tested in a small sample size of recently implanted cochlear implant patients, showing a significant increase over two postoperative timepoints. Using this system, complex impedance is demonstrated as a marker of fibrosis progression that is directly measurable from cochlear implants to enable real-time tracking of fibrosis formation in patients, creating opportunities for earlier treatment intervention to improve cochlear implant efficacy.
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Affiliation(s)
- Simone R de Rijk
- Cambridge Hearing Group, Cambridge, CB2 8AF, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 3 EB, UK
| | - Alexander J Boys
- Cambridge Hearing Group, Cambridge, CB2 8AF, UK
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, UK
| | - Iwan V Roberts
- Cambridge Hearing Group, Cambridge, CB2 8AF, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 3 EB, UK
| | - Chen Jiang
- Cambridge Hearing Group, Cambridge, CB2 8AF, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 3 EB, UK
- Department of Electronic Engineering, Tsinghua University, Beijing, 100190, P. R. China
| | - Charlotte Garcia
- Cambridge Hearing Group, Cambridge, CB2 8AF, UK
- Medical Research Council Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, CB2 7EF, UK
| | - Róisín M Owens
- Cambridge Hearing Group, Cambridge, CB2 8AF, UK
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, UK
| | - Manohar Bance
- Cambridge Hearing Group, Cambridge, CB2 8AF, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 3 EB, UK
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Tan E, Bester C, Collins A, Razmovski T, O'Leary S. Four-Point Impedance and Utricular Dysfunction Is Associated with Postoperative Dizziness after Cochlear Implantation. Otol Neurotol 2023:00129492-990000000-00330. [PMID: 37400267 DOI: 10.1097/mao.0000000000003935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2023]
Abstract
INTRODUCTION Postimplantation dizziness is common, affecting approximately 50% of patients. Theories for dizziness include utricular inflammation, endolymphatic hydrops, and loss of perilymph. Four-point impedance (4PI) is a novel impedance measurement in cochlear implantation that shows potential to predict hearing loss, inflammation, and fibrotic tissue response. Here, we associate 4PI with dizziness after implantation and explore the link with utricular function. METHODS Subjective visual vertical (SVV) as a measure of utricular function was recorded preoperatively as a baseline. 4PI was measured immediately postinsertion. Ongoing follow-up was performed at 1 day, 1 week, and 1 month, postoperatively. At each follow-up, 4PI, SVV, and the patients' subjective experience of dizziness were assessed. DISCUSSION Thirty-eight adults were recruited. One-day 4PI was significantly higher in patients dizzy within the next week (254 Ω vs 171 Ω, p = 0.015). The optimum threshold on receiver operating characteristic curve was 190 Ω, above which patients had 10 times greater odds of developing dizziness (Fisher exact test, OR = 9.95, p = 0.0092). This suggests that 4PI varies with changes in the intracochlear environment resulting in dizziness, such as inflammation or hydrops. SVV significantly deviated away from the operated ear at 1 day (fixed effect estimate = 2.6°, p ≤ 0.0001) and 1 week (fixed effect estimate 2.7°, p ≤ 0.001). CONCLUSION One-day 4PI is a potentially useful marker for detecting postoperative dizziness after cochlear implantation. Of the current theories for postoperative dizziness, inflammation might explain the findings seen here, as would changes in hydrostatic pressure. Future research should focus on detecting and exploring these labyrinthine changes in further detail.
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Affiliation(s)
- Eren Tan
- Department of Otolaryngology, The University of Melbourne, Victoria, Australia
| | - Christofer Bester
- Department of Otolaryngology, The University of Melbourne, Victoria, Australia
| | - Aaron Collins
- Department of Otolaryngology, The University of Melbourne, Victoria, Australia
| | - Tayla Razmovski
- Department of Otolaryngology, The University of Melbourne, Victoria, Australia
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Rahman MT, Chari DA, Ishiyama G, Lopez I, Quesnel AM, Ishiyama A, Nadol JB, Hansen MR. Cochlear implants: Causes, effects and mitigation strategies for the foreign body response and inflammation. Hear Res 2022; 422:108536. [PMID: 35709579 PMCID: PMC9684357 DOI: 10.1016/j.heares.2022.108536] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 04/20/2022] [Accepted: 05/23/2022] [Indexed: 12/15/2022]
Abstract
Cochlear implants provide effective auditory rehabilitation for patients with severe to profound sensorineural hearing loss. Recent advances in cochlear implant technology and surgical approaches have enabled a greater number of patients to benefit from this technology, including those with significant residual low frequency acoustic hearing. Nearly all cochleae implanted with a cochlear implant electrode array develop an inflammatory and fibrotic response. This tissue reaction can have deleterious consequences for implant function, residual acoustic hearing, and the development of the next generation of cochlear prosthetics. This article reviews the current understanding of the inflammatory/foreign body response (FBR) after cochlear implant surgery, its impact on clinical outcome, and therapeutic strategies to mitigate this response. Findings from both in human subjects and animal models across a variety of species are highlighted. Electrode array design, surgical techniques, implant materials, and the degree and type of electrical stimulation are some critical factors that affect the FBR and inflammation. Modification of these factors and various anti-inflammatory pharmacological interventions have been shown to mitigate the inflammatory/FBR response. Ongoing and future approaches that seek to limit surgical trauma and curb the FBR to the implanted biomaterials of the electrode array are discussed. A better understanding of the anatomical, cellular and molecular basis of the inflammatory/FBR response after cochlear implantation has the potential to improve the outcome of current cochlear implants and also facilitate the development of the next generation of neural prostheses.
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Affiliation(s)
- Muhammad T Rahman
- Department of Otolaryngology-Head & Neck Surgery, University of Iowa, Iowa City, IA, USA
| | - Divya A Chari
- Department of Otolaryngology-Head & Neck Surgery, Harvard University, Boston, MA, USA
| | - Gail Ishiyama
- Department of Head & Neck Surgery, University of California Los Angeles, LA, USA
| | - Ivan Lopez
- Department of Head & Neck Surgery, University of California Los Angeles, LA, USA
| | - Alicia M Quesnel
- Department of Otolaryngology-Head & Neck Surgery, Harvard University, Boston, MA, USA
| | - Akira Ishiyama
- Department of Head & Neck Surgery, University of California Los Angeles, LA, USA
| | - Joseph B Nadol
- Department of Otolaryngology-Head & Neck Surgery, Harvard University, Boston, MA, USA
| | - Marlan R Hansen
- Department of Otolaryngology-Head & Neck Surgery, University of Iowa, Iowa City, IA, USA.
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Chan J, Telang R, Kociszewska D, Thorne PR, Vlajkovic SM. A High-Fat Diet Induces Low-Grade Cochlear Inflammation in CD-1 Mice. Int J Mol Sci 2022; 23:5179. [PMID: 35563572 PMCID: PMC9101486 DOI: 10.3390/ijms23095179] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 05/02/2022] [Accepted: 05/04/2022] [Indexed: 02/04/2023] Open
Abstract
There is growing evidence for a relationship between gut dysbiosis and hearing loss. Inflammatory bowel disease, diet-induced obesity (DIO), and type 2 diabetes have all been linked to hearing loss. Here, we investigated the effect of a chronic high-fat diet (HFD) on the development of inner ear inflammation using a rodent model. Three-week-old CD-1 (Swiss) mice were fed an HFD or a control diet for ten weeks. After ten weeks, mouse cochleae were harvested, and markers of cochlear inflammation were assessed at the protein level using immunohistochemistry and at the gene expression level using quantitative real-time RT-PCR. We identified increased immunoexpression of pro-inflammatory biomarkers in animals on an HFD, including intracellular adhesion molecule 1 (ICAM1), interleukin 6 receptor α (IL6Rα), and toll-like-receptor 2 (TLR2). In addition, increased numbers of ionized calcium-binding adapter molecule 1 (Iba1) positive macrophages were found in the cochlear lateral wall in mice on an HFD. In contrast, gene expression levels of inflammatory markers were not affected by an HFD. The recruitment of macrophages to the cochlea and increased immunoexpression of inflammatory markers in mice fed an HFD provide direct evidence for the association between HFD and cochlear inflammation.
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Affiliation(s)
| | | | | | | | - Srdjan M. Vlajkovic
- Department of Physiology and The Eisdell Moore Centre, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; (J.C.); (R.T.); (D.K.); (P.R.T.)
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Swiderski DL, Colesa DJ, Hughes AP, Raphael Y, Pfingst BE. Relationships between Intrascalar Tissue, Neuron Survival, and Cochlear Implant Function. J Assoc Res Otolaryngol 2020; 21:337-352. [PMID: 32691251 PMCID: PMC7445211 DOI: 10.1007/s10162-020-00761-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 07/12/2020] [Indexed: 12/15/2022] Open
Abstract
Fibrous tissue and/or new bone are often found surrounding a cochlear implant in the cochlear scalae. This new intrascalar tissue could potentially limit cochlear implant function by increasing impedance and altering signaling pathways between the implant and the auditory nerve. In this study, we investigated the relationship between intrascalar tissue and 5 measures of implant function in guinea pigs. Variation in both spiral ganglion neuron (SGN) survival and intrascalar tissue was produced by implanting hearing ears, ears deafened with neomycin, and neomycin-deafened ears treated with a neurotrophin. We found significant effects of SGN density on 4 functional measures but adding intrascalar tissue level to the analysis did not explain more variation in any measure than was explained by SGN density alone. These results suggest that effects of intrascalar tissue on electrical hearing are relatively unimportant in comparison to degeneration of the auditory nerve, although additional studies in human implant recipients are still needed to assess the effects of this tissue on complex hearing tasks like speech perception. The results also suggest that efforts to minimize the trauma that aggravates both tissue development and SGN loss could be beneficial.
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Affiliation(s)
- Donald L Swiderski
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Deborah J Colesa
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Aaron P Hughes
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Yehoash Raphael
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Bryan E Pfingst
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA.
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8
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A new method for three-dimensional immunofluorescence study of the cochlea. Hear Res 2020; 392:107956. [PMID: 32464455 DOI: 10.1016/j.heares.2020.107956] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 03/13/2020] [Accepted: 03/26/2020] [Indexed: 01/07/2023]
Abstract
Visualisation of cochlear histopathology in three-dimensions has been long desired in the field of hearing research. This paper outlines a technique that has made this possible and shows a research application in the field of hearing protection after cochlear implantation. The technique utilises robust immunofluorescent labelling followed by effective tissue clearing and fast image acquisition using Light Sheet Microscopy. We can access the health of individual components by immunofluorescent detection of proteins such as myosin VIIa to look at cochlear hair cells, NaKATPase alpha 3 to look at spiral ganglion neurons, and IBA1 to look at macrophages within a single cochlea, whilst maintaining the integrity of fine membranous structures and keeping the cochlear implant in place. This allows the tissue response to cochlear implantation to be studied in detail, including the immune reaction to the implant and the impact on the structure and health of neural components such as hair cells. This technique reduces time and labour required for sectioning of cochleae and can allow visualisation of cellular detail. Use of image analysis software allows conversion of high-resolution image stacks into three-dimensional interactive data sets so volumes and numbers of surfaces can be measured. Immunofluorescent whole cochlea labelling and Light Sheet Microscopy have the capacity to be applied to many questions in hearing research of both the cochlea and vestibular system.
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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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Choong JK, Hampson AJ, Brody KM, Lo J, Bester CW, Gummer AW, Reynolds NP, O'Leary SJ. Nanomechanical mapping reveals localized stiffening of the basilar membrane after cochlear implantation. Hear Res 2019; 385:107846. [PMID: 31786442 DOI: 10.1016/j.heares.2019.107846] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 11/02/2019] [Accepted: 11/10/2019] [Indexed: 01/12/2023]
Abstract
Cochlear implantation leads to many structural changes within the cochlea which can impair residual hearing. In patients with preserved low-frequency hearing, a delayed hearing loss can occur weeks-to-years post-implantation. We explore whether stiffening of the basilar membrane (BM) may be a contributory factor in an animal model. Our objective is to map changes in morphology and Young's modulus of basal and apical areas of the BM after cochlear implantation, using quantitative nanomechanical atomic force microscopy (QNM-AFM) after cochlear implant surgery. Cochlear implantation was undertaken in the guinea pig, and the BM was harvested at four time-points: 1 day, 14 days, 28 days and 84 days post-implantation for QNM-AFM analysis. Auditory brainstem response thresholds were determined prior to implantation and termination. BM tissue showed altered morphology and a progressive increase in Young's modulus, mainly in the apex, over time after implantation. BM tissue from the cochlear base demonstrated areas of extreme stiffness which are likely due to micro-calcification on the BM. In conclusion, stiffening of the BM after cochlear implantation occurs over time, even at sites far apical to a cochlear implant.
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Affiliation(s)
- Jessica K Choong
- Otolaryngology, Department of Surgery, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Amy J Hampson
- Otolaryngology, Department of Surgery, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Kate M Brody
- Otolaryngology, Department of Surgery, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Jonathon Lo
- Otolaryngology, Department of Surgery, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Christofer W Bester
- Otolaryngology, Department of Surgery, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Anthony W Gummer
- Section of Physiological Acoustics and Communication, Department of Otolaryngology, Eberhard-Karls-University Tübingen, Elfriede-Aulhorn-Strasse 5, 72076, Tübingen, Germany
| | - Nicholas P Reynolds
- ARC Training Centre for Biodevices, Swinburne University of Technology, Hawthorn, Australia; Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Australia.
| | - Stephen J O'Leary
- Otolaryngology, Department of Surgery, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia.
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Choong JKL, Lo J, Chambers SA, Hampson AJ, Eastwood HT, O’Leary SJ. Intracochlear tPA infusion may reduce fibrosis caused by cochlear implantation surgery. Acta Otolaryngol 2019; 139:396-402. [PMID: 30950671 DOI: 10.1080/00016489.2019.1587504] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND Experiments show that the extent of ongoing fibrotic change within the cochlea can be determined by the volume and pattern of bleeding within the first 24 h following cochlear implantation. Tissue-type plasminogen activator (tPA) is effective at reducing thrombus volume when administered both within and external to the systemic circulation. AIMS/OBJECTIVES To determine if tPA delivered into the scala tympani immediately following implantation will reduce thrombus volume within the lower basal turn of the cochlea. MATERIALS AND METHODS Guinea pigs were implanted with either 'soft' or 'hard' arrays and administered tPA or saline via an intra-cochlear infusion immediately after implantation. Hearing was checked prior to, and 2 weeks after implantation. Cochleae were then harvested and imaged. RESULTS Animals implanted with 'soft' arrays had 4.2% less tissue response compared with animals implanted with 'hard' arrays. In animals receiving 'soft' arrays, tPA reduced the volume of tissue response (measured by the percentage of the lower basal turn of the scala tympani occupied by tissue response) compared with saline. CONCLUSIONS AND SIGNIFICANCE tPA may be effective in reducing the overall volume of tissue response in routine 'soft' cochlear implantation and may have a greater effect in the event of significant surgical trauma.
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Affiliation(s)
- Jessica Ky-Lee Choong
- aOtolaryngology, Department of Surgery, University of Melbourne, Melbourne, Australia
| | - Jonathon Lo
- aOtolaryngology, Department of Surgery, University of Melbourne, Melbourne, Australia
| | - Scott Andrew Chambers
- aOtolaryngology, Department of Surgery, University of Melbourne, Melbourne, Australia
| | - Amy Judith Hampson
- aOtolaryngology, Department of Surgery, University of Melbourne, Melbourne, Australia
| | | | - Stephen John O’Leary
- aOtolaryngology, Department of Surgery, University of Melbourne, Melbourne, Australia
- bRoyal Victorian Eye and Ear Hospital, Melbourne, Australia
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Changes of Electrocochleographic Responses During Cochlear Implantation Presented at the Annual Meeting of ADANO 2016 in Berlin. Otol Neurotol 2019; 40:e424-e429. [DOI: 10.1097/mao.0000000000001939] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Lo J, Bester C, Collins A, Newbold C, Hampson A, Chambers S, Eastwood H, O'Leary S. Intraoperative force and electrocochleography measurements in an animal model of cochlear implantation. Hear Res 2018; 358:50-58. [DOI: 10.1016/j.heares.2017.11.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 10/07/2017] [Accepted: 11/06/2017] [Indexed: 12/15/2022]
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Dalbert A, Huber A, Veraguth D, Roosli C, Pfiffner F. Assessment of Cochlear Trauma During Cochlear Implantation Using Electrocochleography and Cone Beam Computed Tomography. Otol Neurotol 2017; 37:446-53. [PMID: 26945317 DOI: 10.1097/mao.0000000000000998] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To assess cochlear trauma during cochlear implantation by electrocochleography (ECoG) and cone beam computed tomography (CBCT) and to correlate intraoperative cochlear trauma with postoperative loss of residual hearing. METHODS ECoG recordings to tone bursts at 250, 500, 750, and 1000 Hz and click stimuli were recorded before and after insertion of the cochlear implant electrode array, using an extracochlear recording electrode. CBCTs were conducted within 6 weeks after surgery. Changes of intraoperative ECoG recordings and CBCT findings were correlated with postoperative threshold shifts in pure-tone audiograms. RESULTS Fourteen subjects were included. In three subjects a decrease of low-frequency ECoG responses at 250, 500, 750, and 1000 Hz occurred after insertion of the electrode array. This was associated with no or minimal residual hearing 4 weeks after surgery. ECoG responses to click stimuli were present in six subjects and showed a decrease after insertion of the electrode array in three. This was associated with a mean hearing loss of 21 dB in postoperative pure-tone audiograms. Scalar dislocation of the electrode array was assumed in one subject because of CBCT findings and correlated with a decrease of low-frequency ECoG responses and a complete loss of residual hearing. CONCLUSION Hearing loss of ≤11 dB is not associated with detectable decrease in ECoG recordings during cochlear implantation. However, in a majority of patients with threshold shifts of >11 dB or complete hearing loss, an intraoperative decrease of high- or low-frequency ECoG signals occurs, suggesting acute cochlear trauma.
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Affiliation(s)
- Adrian Dalbert
- University of Zurich and Department of Otorhinolaryngology-Head and Neck Surgery, University Hospital Zurich, Zurich, Switzerland
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Abstract
HYPOTHESIS A review of the most recent literature will provide clinicians with an update of secondary endolymphatic hydrops, aiding in diagnosis and treatment of affected patients. BACKGROUND Secondary endolymphatic hydrops is a pathologic finding of the inner ear resulting in episodic vertigo and intermittent hearing loss. It is a finding for which extensive research is being performed. METHODS A review of the most recent literature on secondary endolymphatic hydrops was performed using PubMed literature search. RESULTS Recent investigation of secondary endolymphatic hydrops has brought attention to traumatic and inflammatory insults as causes for secondary endolymphatic hydrops. Such etiologies, including postsurgical effects of cochlear implantation and endolymphatic sac ablation; otosclerosis and its operative intervention(s); acoustic and mechanical trauma; medications; and systemic inflammatory processes, have been determined as causes of secondary lymphatic hydrops. Histopathological slides for many of the etiologies of secondary endolymphatic hydrops are presented. CONCLUSION Through an understanding of the pathophysiology and etiologies of secondary endolymphatic hydrops, clinicians will gain a better understanding of this complex disease process, which will aid in treatment of patients with this disease process.
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Affiliation(s)
- Ashley P. O’Connell Ferster
- Department of Surgery, Division of Otolaryngology-Head and Neck Surgery, The Pennsylvania State University, College of Medicine, Hershey, Pennsylvania, USA
| | - Sebahattin Cureoglu
- Department of Otolaryngology-Head and Neck Surgery, University of Minnesota, Minneapolis, Minnesota, USA
| | - Nevra Keskin
- Department of Internal Medicine of Ankara University, Ankara, Turkey
- Department of Otolaryngology, Otopathology Laboratory, University of Minnesota, Minneapolis, USA
| | | | - Huseyin Isildak
- Department of Surgery, Division of Otolaryngology-Head and Neck Surgery, The Pennsylvania State University, College of Medicine, Hershey, Pennsylvania, USA
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17
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Fuentes-Santamaría V, Alvarado JC, Melgar-Rojas P, Gabaldón-Ull MC, Miller JM, Juiz JM. The Role of Glia in the Peripheral and Central Auditory System Following Noise Overexposure: Contribution of TNF-α and IL-1β to the Pathogenesis of Hearing Loss. Front Neuroanat 2017; 11:9. [PMID: 28280462 PMCID: PMC5322242 DOI: 10.3389/fnana.2017.00009] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 02/09/2017] [Indexed: 12/12/2022] Open
Abstract
Repeated noise exposure induces inflammation and cellular adaptations in the peripheral and central auditory system resulting in pathophysiology of hearing loss. In this study, we analyzed the mechanisms by which noise-induced inflammatory-related events in the cochlea activate glial-mediated cellular responses in the cochlear nucleus (CN), the first relay station of the auditory pathway. The auditory function, glial activation, modifications in gene expression and protein levels of inflammatory mediators and ultrastructural changes in glial-neuronal interactions were assessed in rats exposed to broadband noise (0.5-32 kHz, 118 dB SPL) for 4 h/day during 4 consecutive days to induce long-lasting hearing damage. Noise-exposed rats developed a permanent threshold shift which was associated with hair cell loss and reactive glia. Noise-induced microglial activation peaked in the cochlea between 1 and 10D post-lesion; their activation in the CN was more prolonged reaching maximum levels at 30D post-exposure. RT-PCR analyses of inflammatory-related genes expression in the cochlea demonstrated significant increases in the mRNA expression levels of pro- and anti-inflammatory cytokines, inducible nitric oxide synthase, intercellular adhesion molecule and tissue inhibitor of metalloproteinase-1 at 1 and 10D post-exposure. In noise-exposed cochleae, interleukin-1β (IL-1β), and tumor necrosis factor α (TNF-α) were upregulated by reactive microglia, fibrocytes, and neurons at all time points examined. In the CN, however, neurons were the sole source of these cytokines. These observations suggest that noise exposure causes peripheral and central inflammatory reactions in which TNF-α and IL-1β are implicated in regulating the initiation and progression of noise-induced hearing loss.
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Affiliation(s)
- Verónica Fuentes-Santamaría
- Instituto de Investigación en Discapacidades NeurológicasAlbacete, Spain; Facultad de Medicina, Universidad de Castilla-La ManchaAlbacete, Spain
| | - Juan Carlos Alvarado
- Instituto de Investigación en Discapacidades NeurológicasAlbacete, Spain; Facultad de Medicina, Universidad de Castilla-La ManchaAlbacete, Spain
| | - Pedro Melgar-Rojas
- Instituto de Investigación en Discapacidades NeurológicasAlbacete, Spain; Facultad de Medicina, Universidad de Castilla-La ManchaAlbacete, Spain
| | - María C Gabaldón-Ull
- Instituto de Investigación en Discapacidades NeurológicasAlbacete, Spain; Facultad de Medicina, Universidad de Castilla-La ManchaAlbacete, Spain
| | - Josef M Miller
- Center for Hearing and Communication Research and Department of Clinical Neuroscience, Karolinska InstitutetStockholm, Sweden; Kresge Hearing Research Institute, University of MichiganAnn Arbor, MI, USA
| | - José M Juiz
- Instituto de Investigación en Discapacidades NeurológicasAlbacete, Spain; Facultad de Medicina, Universidad de Castilla-La ManchaAlbacete, Spain
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18
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Characterisation of cochlear inflammation in mice following acute and chronic noise exposure. Histochem Cell Biol 2016; 146:219-30. [PMID: 27109494 DOI: 10.1007/s00418-016-1436-5] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/11/2016] [Indexed: 12/17/2022]
Abstract
Oxidative stress has been established as the key mechanism of the cochlear damage underlying noise-induced hearing loss, however, emerging evidence suggests that cochlear inflammation may also be a major contributor. This study aimed to improve our understanding of the cochlear inflammatory response associated with acute and chronic noise exposure. C57BL/6 mice were exposed to acute traumatic noise (100 dBSPL, 8-16 kHz for 24 h) and their cochleae collected at various intervals thereafter, up to 7 days. Using quantitative RT-PCR and immunohistochemistry, changes in expression levels of proinflammatory cytokines (TNF-α, IL-1β), chemokines (CCL2) and cell adhesion molecules (ICAM-1) were studied. All gene transcripts displayed similar dynamics of expression, with an early upregulation at 6 h post-exposure, followed by a second peak at 7 days. ICAM-1 immunoexpression increased significantly in the inferior region of the spiral ligament, peaking 24 h post-exposure. The early expression of proinflammatory mediators likely mediates the recruitment and extravasation of inflammatory cells into the noise-exposed cochlea. The occurrence of the latter expression peak is not clear, but it may be associated with reparative processes initiated in response to cochlear damage. Chronic exposure to moderate noise (90 dBSPL, 8-16 kHz, 2 h/day, up to 4 weeks) also elicited an inflammatory response, reaching a maximum after 2 weeks, suggesting that cochlear damage and hearing loss associated with chronic environmental noise exposure may be linked to inflammatory processes in the cochlea. This study thus provides further insight into the dynamics of the cochlear inflammatory response induced by exposure to acute and chronic noise.
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19
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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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