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Nguyen TN, Park JS. Intratympanic drug delivery systems to treat inner ear impairments. JOURNAL OF PHARMACEUTICAL INVESTIGATION 2022. [DOI: 10.1007/s40005-022-00586-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Research Progress of Hair Cell Protection Mechanism. Neural Plast 2020; 2020:8850447. [PMID: 33133179 PMCID: PMC7568815 DOI: 10.1155/2020/8850447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/16/2020] [Accepted: 09/30/2020] [Indexed: 11/17/2022] Open
Abstract
How to prevent and treat hearing-related diseases through the protection of hair cells (HCs) is the focus in the field of hearing in recent years. Hearing loss caused by dysfunction or loss of HCs is the main cause of hearing diseases. Therefore, clarifying the related mechanisms of HC development, apoptosis, protection, and regeneration is the main goal of current hearing research. This review introduces the latest research on mechanism of HC protection and regeneration.
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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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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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Abstract
Hearing loss is present in millions of people worldwide. Current treatment for patients with severe to profound hearing loss consists of cochlear implantation. Providing the cochlear nerve is intact, patients generally benefit greatly from this intervention, frequently achieving significant improvements in speech comprehension. There are, however, some cases where current technology does not provide patients with adequate benefit. Ongoing research in cell transplantation and gene therapy promises to lead to new developments that will improve the function of cochlear implants. Translation of these experimental approaches is presently at an early stage. This review focuses on the application of biological therapies in severe hearing loss and discusses some of the barriers to translating basic scientific research into clinical reality. We emphasize the application of these novel therapies to cochlear implantation.
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Affiliation(s)
- A Roemer
- Klinik für Hals-Nasen-Ohren-Heilkunde OE 6500, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
| | - H Staecker
- Department of Otolaryngology - Head and Neck Surgery, University of Kansas School of Medicine, Kansas City, KS, USA
| | - S Sasse
- Klinik für Hals-Nasen-Ohren-Heilkunde OE 6500, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - T Lenarz
- Klinik für Hals-Nasen-Ohren-Heilkunde OE 6500, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - A Warnecke
- Klinik für Hals-Nasen-Ohren-Heilkunde OE 6500, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
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Abstract
Local drug application to the inner ear offers a number of advantages over systemic delivery. Local drug therapy currently encompasses extracochlear administration (i. e., through intratympanic injection), intracochlear administration (particularly for gene and stem cell therapy), as well as various combinations with auditory neurosensory prostheses, either evaluated in preclinical or clinical studies, or off-label. To improve rehabilitation with cochlear implants (CI), one focus is the development of drug-releasing electrode carriers, e. g., for delivery of glucocorticosteroids, antiapoptotic substances, or neurotrophins to the inner ear. The performance of cochlear implants may thus be improved by protecting neuronal structures from insertion trauma, reducing fibrosis in the inner ear, and by stimulating growth of neuronal structures in the direction of the electrodes. Controlled drug release after extracochlear or intracochlear application in conjunction with a CI can also be achieved by use of a biocompatible, resorbable controlled-release drug-delivery system. Two case reports for intracochlear controlled release drug delivery in combination with cochlear implants are presented. In order to treat progressive reduction in speech discrimination and increased impedance, two cochlear implant patients successfully underwent intracochlear placement of a biocompatible, resorbable drug-delivery system for controlled release of dexamethasone. The drug levels reached in inner ear fluids after different types of local drug application strategies can be calculated using a computer model. The intracochlear drug concentrations calculated in this way were compared for different dexamethasone application strategies.
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Khater A, El-Anwar MW. Methods of Hearing Preservation during Cochlear Implantation. Int Arch Otorhinolaryngol 2017; 21:297-301. [PMID: 28680501 PMCID: PMC5495597 DOI: 10.1055/s-0036-1585094] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 06/03/2016] [Indexed: 11/15/2022] Open
Abstract
Introduction Recent advances in surgical techniques and electrode design have made residual hearing preservation during cochlear implantation (CI) possible, achievable, and desirable. Objectives The objective of this study was to review the literature regarding methods used for hearing preservation during CI surgery. Data Synthesis We performed a search in the LILACS, MEDLINE, SciELO, PubMed databases, and Cochrane Library, using the keywords CI, hearing preservation, CI electrode design, and CI soft surgery. We fully read about 15 studies that met the criteria described in "study selection". The studies showed that several factors could contribute to possible cochlear damage during or after CI surgery and must be kept in mind; mechanical damage during electrode insertion, shock waves in the perilymph fluid due to implantation, acoustic trauma due to drilling, loss of perilymph and disruption of inner ear fluid homeostasis, potential bacterial infection, and secondary intracochlear fibrous tissue formation. The desire to preserve residual hearing has led to the development of the soft-surgery protocols with 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 questionable. The site of entry into the cochlea, electrode design, and the depth of insertion are also important contributing factors. Conclusion Hearing preservation would be useful for CI patients to benefit from the residual low frequency, as well as for the children who could be candidate for future regenerative hair cell therapy.
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Affiliation(s)
- Ahmed Khater
- Department of Otorhinolaryngology Head and Neck Surgery, Zagazig University, Zagazig, Egypt
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Abstract
OBJECTIVE To critically review and evaluate the proposed mechanisms and documented results of the therapeutics currently in active clinical drug trials for the treatment of sensorineural hearing loss. DATA SOURCES US National Institutes of Health (NIH) Clinical Trials registry, MEDLINE/PubMed. STUDY SELECTION & DATA EXTRACTION A review of the NIH Clinical Trials registry identified candidate hearing loss therapies, and supporting publications were acquired from MEDLINE/PubMed. Proof-of-concept, therapeutic mechanisms, and clinical outcomes were critically appraised. DATA SYNTHESIS Twenty-two active clinical drug trials registered in the United States were identified, and six potentially therapeutic molecules were reviewed. Of the six molecules reviewed, four comprised mechanisms pertaining to mitigating oxidative stress pathways that presumably lead to inner ear cell death. One remaining therapy sought to manipulate the cell death cascade, and the last remaining therapy was a novel cell replacement therapy approach to introduce a transcription factor that promotes hair cell regeneration. CONCLUSION A common theme in recent clinical trials registered in the United States appears to be the targeting of cell death pathways and influence of oxidant stressors on cochlear sensory neuroepithelium. In addition, a virus-delivered cell replacement therapy would be the first of its kind should it prove safe and efficacious. Significant challenges for bringing these bench-to-bedside therapies to market remain. It is never assured that results in non-human animal models translate to effective therapies in the setting of human biology. Moreover, as additional processes are described in association with hearing loss, such as an immune response and loss of synaptic contacts, additional pathways for targeting become available.
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Affiliation(s)
- Matthew G. Crowson
- Division of Head & Neck Surgery & Communication Sciences, Department of Surgery, Duke University Medical Center, Durham, NC USA
| | - Ronna Hertzano
- Department of Otorhinolaryngology Head & Neck Surgery, Anatomy and Neurobiology and Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD USA
| | - Debara Tucci
- Division of Head & Neck Surgery & Communication Sciences, Department of Surgery, Duke University Medical Center, Durham, NC USA
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Roemer A, Staecker H, Sasse S, Lenarz T, Warnecke A. [Biological therapies in otology. German version]. HNO 2017; 65:571-585. [PMID: 28204850 DOI: 10.1007/s00106-016-0304-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Millions of people worldwide suffer from hearing loss. Current treatment for patients with severe to profound hearing loss consists of cochlear implants. Providing the cochlear nerve is intact, patients generally benefit enormously from this intervention, frequently achieving significant improvements in speech comprehension. There are, however, some cases where current technology does not provide patients with adequate benefit. New therapeutic concepts based on cell transplantation and gene therapy are developing rapidly, at least in the research sector. Compared to the wealth of basic research available in this area, translation of these new experimental approaches into clinical application is presently at a very early stage. The current review focuses on translatable treatment concepts and discusses the barriers that need to be overcome in order to translate basic scientific research into clinical reality. Furthermore, the first examples of clinical application of biological therapies in severe hearing loss are presented, particularly in connection with cochlear implants.
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Affiliation(s)
- A Roemer
- Klinik für Hals-Nasen-Ohren-Heilkunde OE 6500 Hannover Medical School, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Deutschland.
| | - H Staecker
- Department of Otolaryngology - Head and Neck Surgery, University of Kansas School of Medicine, Kansas City, KS, USA
| | - S Sasse
- Klinik für Hals-Nasen-Ohren-Heilkunde OE 6500 Hannover Medical School, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Deutschland
| | - T Lenarz
- Klinik für Hals-Nasen-Ohren-Heilkunde OE 6500 Hannover Medical School, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Deutschland
| | - A Warnecke
- Klinik für Hals-Nasen-Ohren-Heilkunde OE 6500 Hannover Medical School, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Deutschland
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The Effect of Round Window Sealants on Delayed Hearing Loss in a Guinea Pig Model of Cochlear Implantation. Otol Neurotol 2016; 37:1024-31. [DOI: 10.1097/mao.0000000000001132] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
Cochlear implantation and cochlear implants (CIs) have a long history filled with innovations that have resulted in the high-performing device's currently available. Several promising technologies have been reviewed in this article, which hold the promise to drive performance even higher. Remote CI programming, totally implanted devices, improved neural health and survival through targeted drug therapy and delivery, intraneural electrode placement, electroacoustical stimulation and hybrid CIs, and methods to enhance the neural-prosthesis interface are evolving areas of innovation reviewed in this article.
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Affiliation(s)
- Joseph P Roche
- Department of Otolaryngology - Head and Neck Surgery, The University of Iowa Carver College of Medicine, 21151 Pomerantz Family Pavilion, 200 Hawkins Drive, Iowa City, IA 52242-1089, USA
| | - Marlan R Hansen
- Department of Otolaryngology - Head and Neck Surgery, The University of Iowa Carver College of Medicine, 21151 Pomerantz Family Pavilion, 200 Hawkins Drive, Iowa City, IA 52242-1089, USA; Department of Neurosurgery, The University of Iowa Carver College of Medicine, 200 Hawkins Drive, Iowa City, IA 52242-1089, USA.
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Dinh CT, Goncalves S, Bas E, Van De Water TR, Zine A. Molecular regulation of auditory hair cell death and approaches to protect sensory receptor cells and/or stimulate repair following acoustic trauma. Front Cell Neurosci 2015; 9:96. [PMID: 25873860 PMCID: PMC4379916 DOI: 10.3389/fncel.2015.00096] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2014] [Accepted: 03/03/2015] [Indexed: 12/20/2022] Open
Abstract
Loss of auditory sensory hair cells (HCs) is the most common cause of hearing loss. This review addresses the signaling pathways that are involved in the programmed and necrotic cell death of auditory HCs that occur in response to ototoxic and traumatic stressor events. The roles of inflammatory processes, oxidative stress, mitochondrial damage, cell death receptors, members of the mitogen-activated protein kinase (MAPK) signal pathway and pro- and anti-cell death members of the Bcl-2 family are explored. The molecular interaction of these signal pathways that initiates the loss of auditory HCs following acoustic trauma is covered and possible therapeutic interventions that may protect these sensory HCs from loss via apoptotic or non-apoptotic cell death are explored.
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Affiliation(s)
- Christine T Dinh
- University of Miami Ear Institute, University of Miami Miller School of Medicine Miami, FL, USA
| | - Stefania Goncalves
- University of Miami Ear Institute, University of Miami Miller School of Medicine Miami, FL, USA
| | - Esperanza Bas
- University of Miami Ear Institute, University of Miami Miller School of Medicine Miami, FL, USA
| | - Thomas R Van De Water
- University of Miami Ear Institute, University of Miami Miller School of Medicine Miami, FL, USA
| | - Azel Zine
- Integrative and Adaptive Neurosciences, Aix-Marseille Université, CNRS, UMR 7260 Marseille, France ; Faculty of Pharmacy, Biophysics Department, University of Montpellier Montpellier, France
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Deloche C, Lopez-Lazaro L, Mouz S, Perino J, Abadie C, Combette JM. XG-102 administered to healthy male volunteers as a single intravenous infusion: a randomized, double-blind, placebo-controlled, dose-escalating study. Pharmacol Res Perspect 2014; 2:e00020. [PMID: 25505576 PMCID: PMC4186400 DOI: 10.1002/prp2.20] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 11/14/2013] [Accepted: 11/26/2013] [Indexed: 12/11/2022] Open
Abstract
The aim of the study is to evaluate the safety, tolerability and pharmacokinetics (PK) of the JNK inhibitor XG-102 in a randomized, double blind, placebo controlled, sequential ascending dose parallel group Phase 1 Study. Three groups of male subjects received as randomly assigned ascending single XG-102 doses (10, 40, and 80 μg/kg; 6 subjects per dose) or placebo (2 subjects per dose) as an intravenous (IV) infusion over 60 min. Safety and tolerability were assessed by physical examination, vital signs, electrocardiography, eye examination, clinical laboratory tests and adverse events (AEs). PK was analyzed using noncompartmental methods. All reported AEs were mild to moderate and neither their number nor their distribution by System Organ Class suggest a dose relationship. Only headache and fatigue were considered probably or possibly study drug related. Headache frequency was similar for active and placebo, consequently this was not considered to be drug related but probably to study conditions. The other examinations did not show clinically relevant deviations or trends suggesting a XG-102 relationship. Geometric mean half-life was similar among doses, ranging from 0.36 to 0.65 h. Geometric mean XG-102 AUC0–last increased more than linearly with dose, 90% confidence intervals (CIs) did not overlap for the two highest doses. Geometric mean dose normalized Cmax values suggest a more than linear increase with dose but 90% CIs overlap. It may be concluded that XG-102 single IV doses of 10–80 μg/kg administered over 1 h to healthy male subjects were safe and well tolerated.
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Eshraghi AA, Nazarian R, Telischi FF, Rajguru SM, Truy E, Gupta C. The cochlear implant: historical aspects and future prospects. Anat Rec (Hoboken) 2012; 295:1967-80. [PMID: 23044644 DOI: 10.1002/ar.22580] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 07/24/2012] [Indexed: 02/06/2023]
Abstract
The cochlear implant (CI) is the first effective treatment for deafness and severe losses in hearing. As such, the CI is now widely regarded as one of the great advances in modern medicine. This article reviews the key events and discoveries that led up to the current CI systems, and we review and present some among the many possibilities for further improvements in device design and performance. The past achievements include: (1) development of reliable devices that can be used over the lifetime of a patient; (2) development of arrays of implanted electrodes that can stimulate more than one site in the cochlea; and (3) progressive and large improvements in sound processing strategies for CIs. In addition, cooperation between research organizations and companies greatly accelerated the widespread availability and use of safe and effective devices. Possibilities for the future include: (1) use of otoprotective drugs; (2) further improvements in electrode designs and placements; (3) further improvements in sound processing strategies; (4) use of stem cells to replace lost sensory hair cells and neural structures in the cochlea; (5) gene therapy; (6) further reductions in the trauma caused by insertions of electrodes and other manipulations during implant surgeries; and (7) optical rather electrical stimulation of the auditory nerve. Each of these possibilities is the subject of active research. Although great progress has been made to date in the development of the CI, including the first substantial restoration of a human sense, much more progress seems likely and certainly would not be a surprise.
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Affiliation(s)
- Adrien A Eshraghi
- Department of Otolaryngology, University of Miami Ear Institute, University of Miami Miller School of Medicine, Miami, Florida 33136-1015, USA.
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Abstract
OBJECTIVE AM-111, a cell-permeable peptide inhibitor of c-Jun N-terminal kinase, was investigated for its protective effects against ischemic damage of the cochlea in gerbils. METHODS Transient cochlear ischemia was introduced in animals by occluding the bilateral vertebral arteries for l5 minutes. Then, 10 μl of AM-111 at a concentration of l, 10, or 100 μM in hyaluronic acid gel formulation was applied onto the round window 30 minutes after the insult. Gel without active substance was used in a control group. Treatment effects were evaluated by auditory brainstem response (ABR) and histology of the inner ear. RESULTS In controls, transient cochlear ischemia caused a 25.0 ± 5.0 dB increase in the ABR threshold at 8 kHz and a decrease of 13.3 ± 2.3% in inner hair cells at the basal turn on Day 7. Ischemic damage was mild at 2 and 4 kHz. When the animals were treated with AM-111 at 100 μM, cochlear damage was significantly reduced: the increase in ABR threshold was 3.3 ± 2.4 dB at 8 kHz, and the inner hair cell loss was 3.1 ± 0.6% at the basal turn on Day 7. The effects of AM-111 were concentration dependent: 100 μM was more effective than 1 or 10 μM. CONCLUSION Direct application of AM-111 in gel formulation on the round window was effective in preventing acute hearing loss because of transient cochlear ischemia.
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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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Eshraghi AA, Adil E, He J, Graves R, Balkany TJ, Van De Water TR. Local Dexamethasone Therapy Conserves Hearing in an Animal Model of Electrode Insertion Trauma-Induced Hearing Loss. Otol Neurotol 2007; 28:842-9. [PMID: 17471110 DOI: 10.1097/mao.0b013e31805778fc] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
HYPOTHESIS The progressive loss of hearing that develops after electrode insertion trauma (EIT) can be attenuated by local dexamethasone (DXM) therapy. BACKGROUND Hearing loss (HL) that develops after cochlear implant EIT occurs in two stages in laboratory animals, that is, an immediate loss followed by a progressive loss. Direct infusion of DXM into the guinea pig cochlea can attenuate both ototoxin- and noise-induced HL. MATERIALS AND METHODS Auditory-evoked brainstem responses (ABRs) of guinea pigs were measured for 4 frequencies (i.e., 0.5, 1, 4, and 16 kHz) before, immediately after, and more than 30 days post-EIT for experimental (EIT,EIT + artificial perilymph, and EIT + DXM) and for the contralateral unoperated cochleae of each group. An electrode analog of 0.14-mm diameter was inserted through a basal turn cochleostomy for a depth of 3 mm and withdrawn. DXM in artificial perilymph was delivered immediately post-EIT into the scala tympani via a miniosmotic pump for 8 days. RESULTS The ABR thresholds of EIT animals increased progressively post-EIT. Contralateral unoperated cochleae had no significant changes in ABR thresholds. Immediately post-EIT, that is, Day 0, the DXM-treated animals exhibited a significant HL at 1, 4, and 16 kHz, but this HL was no longer significant by Day 30 compared with contralateral control ears. CONCLUSION The results from immediate local treatment of the cochlea with DXM in an animal model of EIT-induced HL suggest a novel therapeutic strategy for hearing conservation by attenuating the progressive HL that can result from the process of electrode array insertion during cochlear implantation.
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Affiliation(s)
- Adrien A Eshraghi
- Cochlear Implant Research Program, University of Miami Ear Institute, Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, FL, USA
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