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Geerardyn A, Wils I, Putzeys T, Fierens G, Wouters J, Verhaert N. The impact of round window reinforcement on middle and inner ear mechanics with air and bone conduction stimulation. Hear Res 2024; 450:109049. [PMID: 38850830 DOI: 10.1016/j.heares.2024.109049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 05/24/2024] [Accepted: 05/28/2024] [Indexed: 06/10/2024]
Abstract
The round window (RW) membrane plays an important role in normal inner ear mechanics. Occlusion or reinforcement of the RW has been described in the context of congenital anomalies or after cochlear implantation and is applied as a surgical treatment for hyperacusis. Multiple lumped and finite element models predict a low-frequency hearing loss with air conduction of up to 20 dB after RW reinforcement and limited to no effect on hearing with bone conduction stimulation. Experimental verification of these results, however, remains limited. Here, we present an experimental study measuring the impact of RW reinforcement on the middle and inner ear mechanics with air and bone conduction stimulation. In a within-specimen repeated measures design with human cadaveric specimens (n = 6), we compared the intracochlear pressures in scala vestibuli (PSV) and scala tympani (PST) before and after RW reinforcement with soft tissue, cartilage, and bone cement. The differential pressure (PDIFF) across the basilar membrane - known to be closely related to the hearing sensation - was calculated as the complex difference between PSV and PST. With air conduction stimulation, both PSV and PSTincreased on average up to 22 dB at frequencies below 1500 Hz with larger effect sizes for PST compared to PSV. The PDIFF, in contrast, decreased up to 11 dB at frequencies between 700 and 800 Hz after reinforcement with bone cement. With bone conduction, the average within-specimen effects were less than 5 dB for either PSV, PST, or PDIFF. The inter-specimen variability with bone conduction, however, was considerably larger than with air conduction. This experimental study shows that RW reinforcement impacts air conduction stimulation at low frequencies. Bone conduction stimulation seems to be largely unaffected. From a clinical point of view, these results support the hypothesis that delayed loss of air conduction hearing after cochlear implantation could be partially explained by the impact of RW reinforcement.
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Affiliation(s)
- Alexander Geerardyn
- ExpORL, Department of Neurosciences, KU Leuven, Leuven, Belgium; Department of Otorhinolaryngology-Head and Neck Surgery, University Hospitals Leuven, Leuven Belgium
| | - Irina Wils
- ExpORL, Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Tristan Putzeys
- ExpORL, Department of Neurosciences, KU Leuven, Leuven, Belgium; Laboratory of Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Leuven, Belgium
| | - Guy Fierens
- ExpORL, Department of Neurosciences, KU Leuven, Leuven, Belgium; Cochlear Technology Centre, Mechelen, Belgium
| | - Jan Wouters
- ExpORL, Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Nicolas Verhaert
- ExpORL, Department of Neurosciences, KU Leuven, Leuven, Belgium; Department of Otorhinolaryngology-Head and Neck Surgery, University Hospitals Leuven, Leuven Belgium.
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Xiao AY, Lopez IA, Ishiyama G, Ishiyama A. Expression of TGFβ-1 and CTGF in the Implanted Cochlea and its Implication on New Tissue Formation. Otol Neurotol 2024; 45:810-817. [PMID: 38995724 PMCID: PMC11250773 DOI: 10.1097/mao.0000000000004226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/14/2024]
Abstract
HYPOTHESIS Transforming growth factor beta-1 (TGFβ-1) and connective tissue growth factor (CTGF) are upregulated in the implanted human cochlea. BACKGROUND Cochlear implantation can lead to insertion trauma and intracochlear new tissue formation, which can detrimentally affect implant performance. TGFβ-1 and CTGF are profibrotic proteins implicated in various pathologic conditions, but little is known about their role in the cochlea. The present study aimed to characterize the expression of these proteins in the human implanted cochlea. METHODS Archival human temporal bones (HTB) acquired from 12 patients with previous CI and histopathological evidence of new tissue formation as well as surgical samples of human intracochlear scar tissue surrounding the explanted CI were used in this study. Histopathologic analysis of fibrosis and osteoneogenesis was conducted using H&E. Protein expression was characterized using immunofluorescence. RNA expression from surgical specimens of fibrotic tissue surrounding the CI was quantified using qRT-PCR. RESULTS TGFβ-1 and CTGF protein expressions were upregulated in the areas of fibrosis and osteoneogenesis surrounding the CI HTB. Similarly, surgical samples demonstrated upregulation of protein and mRNA expression of TGFβ-1 and mild upregulation of CTGF compared with control. TGFβ-1 was expressed diffusely within the fibrous capsule, whereas CTGF was expressed in the thickened portion toward the modiolus and the fibrosis-osteoneogensis junction. CONCLUSION To our knowledge, this is the first study to demonstrate increased expression of TGFβ-1 and CTGF in the human implanted cochlea and may provide better understanding of the mechanism behind this pathogenic process to better develop future mitigating interventions.
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Affiliation(s)
- Adam Y. Xiao
- Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Ivan A. Lopez
- Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Gail Ishiyama
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Akira Ishiyama
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California
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Reiss LAJ, Lawrence MB, Omelchenko IA, He W, Kirk JR. Chronic Electro-Acoustic Stimulation May Interfere With Electric Threshold Recovery After Cochlear Implantation in the Aged Guinea Pig. Ear Hear 2024:00003446-990000000-00310. [PMID: 38992863 DOI: 10.1097/aud.0000000000001545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2024]
Abstract
OBJECTIVES Electro-acoustic stimulation (EAS) combines electric stimulation via a cochlear implant (CI) with residual low-frequency acoustic hearing, with benefits for music appreciation and speech perception in noise. However, many EAS CI users lose residual acoustic hearing, reducing this benefit. The main objectives of this study were to determine whether chronic EAS leads to more hearing loss compared with CI surgery alone in an aged guinea pig model, and to assess the relationship of any hearing loss to histology measures. Conversely, it is also important to understand factors impacting efficacy of electric stimulation. If one contributor to CI-induced hearing loss is damage to the auditory nerve, both acoustic and electric thresholds will be affected. Excitotoxicity from EAS may also affect electric thresholds, while electric stimulation is osteogenic and may increase electrode impedances. Hence, secondary objectives were to assess how electric thresholds are related to the amount of residual hearing loss after CI surgery, and how EAS affects electric thresholds and impedances over time. DESIGN Two groups of guinea pigs, aged 9 to 21 months, were implanted with a CI in the left ear. Preoperatively, the animals had a range of hearing losses, as expected for an aged cohort. At 4 weeks after surgery, the EAS group (n = 5) received chronic EAS for 8 hours a day, 5 days a week, for 20 weeks via a tether system that allowed for free movement during stimulation. The nonstimulated group (NS; n = 6) received no EAS over the same timeframe. Auditory brainstem responses (ABRs) and electrically evoked ABRs (EABRs) were recorded at 3 to 4 week intervals to assess changes in acoustic and electric thresholds over time. At 24 weeks after surgery, cochlear tissue was harvested for histological evaluation, only analyzing animals without electrode extrusions (n = 4 per ear). RESULTS Cochlear implantation led to an immediate worsening of ABR thresholds peaking between 3 and 5 weeks after surgery and then recovering and stabilizing by 5 and 8 weeks. Significantly greater ABR threshold shifts were seen in the implanted ears compared with contralateral, non-implanted control ears after surgery. After EAS and termination, no significant additional ABR threshold shifts were seen in the EAS group compared with the NS group. A surprising finding was that NS animals had significantly greater recovery in EABR thresholds over time, with decreases (improvements) of -51.8 ± 33.0 and -39.0 ± 37.3 c.u. at 12 and 24 weeks, respectively, compared with EAS animals with EABR threshold increases (worsening) of +1.0 ± 25.6 and 12.8 ± 44.3 c.u. at 12 and 24 weeks. Impedance changes over time did not differ significantly between groups. After exclusion of cases with electrode extrusion or significant trauma, no significant correlations were seen between ABR and EABR thresholds, or between ABR thresholds with histology measures of inner/outer hair cell counts, synaptic ribbon counts, stria vascularis capillary diameters, or spiral ganglion cell density. CONCLUSIONS The findings do not indicate that EAS significantly disrupts acoustic hearing, although the small sample size limits this interpretation. No evidence of associations between hair cell, synaptic ribbon, spiral ganglion cell, or stria vascularis with hearing loss after cochlear implantation was seen when surgical trauma is minimized. In cases of major trauma, both acoustic thresholds and electric thresholds were elevated, which may explain why CI-only outcomes are often better when trauma and hearing loss are minimized. Surprisingly, chronic EAS (or electric stimulation alone) may negatively impact electric thresholds, possibly by prevention of recovery of the auditory nerve after CI surgery. More research is needed to confirm the potentially negative impact of chronic EAS on electric threshold recovery.
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Affiliation(s)
- Lina A J Reiss
- Department of Otolaryngology-Head and Neck Surgery, Oregon Health & Science University, Portland, Oregon, USA
| | - Melissa B Lawrence
- Department of Otolaryngology-Head and Neck Surgery, Oregon Health & Science University, Portland, Oregon, USA
| | - Irina A Omelchenko
- Department of Otolaryngology-Head and Neck Surgery, Oregon Health & Science University, Portland, Oregon, USA
| | - Wenxuan He
- Department of Otolaryngology-Head and Neck Surgery, Oregon Health & Science University, Portland, Oregon, USA
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Wang L, Zhang R, Jiang L, Gao S, Wu J, Jiao Y. Biomaterials as a new option for treating sensorineural hearing loss. Biomater Sci 2024. [PMID: 38979939 DOI: 10.1039/d4bm00518j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Sensorineural hearing loss (SNHL) usually involves damage to complex auditory pathways such as inner ear cells and auditory nerves. The highly intricate and nuanced characteristics of these cells render their repair and regeneration extremely challenging, making it difficult to restore hearing to normal levels once it has been compromised. The effectiveness of traditional drugs is so minimal that they provide little help with the treatment. Fortunately, extensive experiments have demonstrated that combining biomaterials with conventional techniques significantly enhances drug effectiveness. This article reviews the research progress of biomaterials in protecting hair cells and the auditory nerve, repairing genes related to hearing, and developing artificial cochlear materials. By organizing the knowledge presented in this article, perhaps new insights can be provided for the clinical management of SNHL.
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Affiliation(s)
- Liwen Wang
- Department of Otorhinolaryngology Head and Neck Surgery, Guangzhou Twelfth People's Hospital (The Affiliated Twelfth People's Hospital of Guangzhou Medical University), Guangzhou 510620, China
- Institute of Otorhinolaryngology, Head and Neck Surgery, Guangzhou Medical University, Guangzhou 510620, China.
| | - Ruhe Zhang
- Department of Hematology, The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen 518107, China
| | - Linlan Jiang
- Department of Otorhinolaryngology Head and Neck Surgery, Guangzhou Twelfth People's Hospital (The Affiliated Twelfth People's Hospital of Guangzhou Medical University), Guangzhou 510620, China
- Institute of Otorhinolaryngology, Head and Neck Surgery, Guangzhou Medical University, Guangzhou 510620, China.
| | - Shuyi Gao
- Department of Otorhinolaryngology Head and Neck Surgery, Guangzhou Twelfth People's Hospital (The Affiliated Twelfth People's Hospital of Guangzhou Medical University), Guangzhou 510620, China
- Institute of Otorhinolaryngology, Head and Neck Surgery, Guangzhou Medical University, Guangzhou 510620, China.
| | - Jun Wu
- Institute of Otorhinolaryngology, Head and Neck Surgery, Guangzhou Medical University, Guangzhou 510620, China.
- Bioscience and Biomedical Engineering Thrust, The Hong Kong University of Science and Technology (Guangzhou), Nansha, Guangzhou 511400, China.
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Yuenong Jiao
- Department of Otorhinolaryngology Head and Neck Surgery, Guangzhou Twelfth People's Hospital (The Affiliated Twelfth People's Hospital of Guangzhou Medical University), Guangzhou 510620, China
- Institute of Otorhinolaryngology, Head and Neck Surgery, Guangzhou Medical University, Guangzhou 510620, China.
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O'Malley JT, Wu PZ, Kaur C, Gantz BJ, Hansen MR, Quesnel AM, Liberman MC. Delayed hearing loss after cochlear implantation: Re-evaluating the role of hair cell degeneration. Hear Res 2024; 447:109024. [PMID: 38735179 PMCID: PMC11134194 DOI: 10.1016/j.heares.2024.109024] [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: 03/18/2024] [Revised: 04/18/2024] [Accepted: 04/26/2024] [Indexed: 05/14/2024]
Abstract
Delayed loss of residual acoustic hearing after cochlear implantation is a common but poorly understood phenomenon due to the scarcity of relevant temporal bone tissues. Prior histopathological analysis of one case of post-implantation hearing loss suggested there were no interaural differences in hair cell or neural degeneration to explain the profound loss of low-frequency hearing on the implanted side (Quesnel et al., 2016) and attributed the threshold elevation to neo-ossification and fibrosis around the implant. Here we re-evaluated the histopathology in this case, applying immunostaining and improved microscopic techniques for differentiating surviving hair cells from supporting cells. The new analysis revealed dramatic interaural differences, with a > 80 % loss of inner hair cells in the cochlear apex on the implanted side, which can account for the post-implantation loss of residual hearing. Apical degeneration of the stria further contributed to threshold elevation on the implanted side. In contrast, spiral ganglion cell survival was reduced in the region of the electrode on the implanted side, but apical counts in the two ears were similar to that seen in age-matched unimplanted control ears. Almost none of the surviving auditory neurons retained peripheral axons throughout the basal half of the cochlea. Relevance to cochlear implant performance is discussed.
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Affiliation(s)
- Jennifer T O'Malley
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, 02114, USA; Dept of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA, 02115, USA
| | - Pei-Zhe Wu
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, 02114, USA; Dept of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA, 02115, USA
| | - Charanjeet Kaur
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, 02114, USA; Dept of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA, 02115, USA
| | - Bruce J Gantz
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, IA, 52242, USA; Department of Neurosurgery, University of Iowa, Iowa City, IA, 52242
| | - Marlan R Hansen
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, IA, 52242, USA; Department of Neurosurgery, University of Iowa, Iowa City, IA, 52242
| | - Alicia M Quesnel
- Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, 02114, USA; Dept of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA, 02115, USA
| | - M Charles Liberman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, 02114, USA; Dept of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA, 02115, USA.
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Peel A, Bennion D, Horne R, Hansen MR, Guymon CA. Photografted Zwitterionic Hydrogel Coating Durability for Reduced Foreign Body Response to Cochlear Implants. ACS APPLIED BIO MATERIALS 2024; 7:3124-3135. [PMID: 38584364 PMCID: PMC11110053 DOI: 10.1021/acsabm.4c00156] [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: 02/01/2024] [Revised: 03/21/2024] [Accepted: 03/22/2024] [Indexed: 04/09/2024]
Abstract
The durability of photografted zwitterionic hydrogel coatings on cochlear implant biomaterials was examined to determine the viability of these antifouling surfaces during insertion and long-term implant usage. Tribometry was used to determine the effect of zwitterionic coatings on the lubricity of surfaces with varying hydration levels, applied normal force, and time frame. Additionally, flexural resistance was investigated using mandrel bending. Ex vivo durability was assessed by determining the coefficient of friction between tissues and treated surfaces. Furthermore, cochlear implantation force was measured using cadaveric human cochleae. Hydrated zwitterionic hydrogel coatings reduced frictional resistance approximately 20-fold compared to uncoated PDMS, which led to significantly lower mean force experienced by coated cochlear implants during insertion compared to uncoated systems. Under flexural force, zwitterionic films resisted failure for up to 60 min of desiccation. The large increase in lubricity was maintained for 20 h under continual force while hydrated. For loosely cross-linked systems, films remained stable and lubricious even after rehydration following complete drying. All coatings remained hydrated and functional under frictional force for at least 30 min in ambient conditions allowing drying, with lower cross-link densities showing the greatest longevity. Moreover, photografted zwitterionic hydrogel samples showed no evidence of degradation and nearly identical lubricity before and after implantation. This work demonstrates that photografted zwitterionic hydrogel coatings are sufficiently durable to maintain viability before, during, and after implantation. Mechanical properties, including greatly increased lubricity, are preserved after complete drying and rehydration for various applied forces. Additionally, this significantly enhanced lubricity translates to significantly decreased force during insertion of implants which should result in less trauma and scarring.
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Affiliation(s)
- Adreann Peel
- Department
of Chemical and Biochemical Engineering, University of Iowa, Iowa City, Iowa 52242, United States
| | - Douglas Bennion
- Department
of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa 52242, United States
| | - Ryan Horne
- Department
of Chemical and Biochemical Engineering, University of Iowa, Iowa City, Iowa 52242, United States
| | - Marlan R. Hansen
- Department
of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa 52242, United States
| | - C. Allan Guymon
- Department
of Chemical and Biochemical Engineering, University of Iowa, Iowa City, Iowa 52242, United States
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Yancey KL, Patro A, Smetak M, Perkins EL, Isaacson B, Bennett ML, O'Malley M, Haynes DS, Hunter JB. Evaluating calcium channel blockers and bisphosphonates as otoprotective agents in cochlear implantation hearing preservation candidates. Cochlear Implants Int 2024:1-9. [PMID: 38738388 DOI: 10.1080/14670100.2024.2338003] [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: 05/14/2024]
Abstract
OBJECTIVES Evaluate potential effects of calcium channel blockers (CCB) and bisphosphonates (BP) on residual hearing following cochlear implantation. METHODS Medications of 303 adult hearing preservation (HP) candidates (low frequency pure tone average [LFPTA] of 125, 250, and 500 Hz ≤80 dB HL) were reviewed. Postimplantation LFPTA of patients taking CCBs and BPs were compared to controls matched by age and preimplantation LFPTA. RESULTS Twenty-six HP candidates were taking a CCB (N = 14) or bisphosphonate (N = 12) at implantation. Median follow-up was 1.37 years (range 0.22-4.64y). Among subjects with initial HP, 29% (N = 2 of 7) CCB users compared to 50% (N = 2 of 4) controls subsequently lost residual hearing 3-6 months later (OR = 0.40, 95% CI = 0.04-4.32, p = 0.58). None of the four BP patients with initial HP experienced delayed loss compared to 50% (N = 2 of 4) controls with initial HP (OR = 0.00, 95% CI = 0.00-1.95, P = 0.43). Two CCB and one BP patients improved to a LFPTA <80 dB HL following initial unaided thresholds that suggested loss of residual hearing. DISCUSSION There were no significant differences in the odds of delayed loss of residual hearing with CCBs or BPs. CONCLUSION Further investigation into potential otoprotective adjuvants for maintaining residual hearing following initial successful hearing preservation is warranted, with larger cohorts and additional CCB/BP agents.
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Affiliation(s)
- Kristen L Yancey
- Department of Otolaryngology-Head and Neck Surgery, Weill Cornell Medical Center/New York Presbyterian Hospital, New York, NY, USA
| | - Ankita Patro
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Miriam Smetak
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Elizabeth L Perkins
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Brandon Isaacson
- Department of Otolaryngology-Head and Neck Surgery, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Marc L Bennett
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Matthew O'Malley
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - David S Haynes
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jacob B Hunter
- Department of Otolaryngology-Head and Neck Surgery, Thomas Jefferson University Hospital, Philadelphia, PA, USA
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Lee C, Hartsock JJ, Salt AN, Lichtenhan JT. A Guinea Pig Model Suggests That Objective Assessment of Acoustic Hearing Preservation in Human Ears With Cochlear Implants Is Confounded by Shifts in the Spatial Origin of Acoustically Evoked Potential Measurements Along the Cochlear Length. Ear Hear 2024; 45:666-678. [PMID: 38178312 DOI: 10.1097/aud.0000000000001457] [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: 01/06/2024]
Abstract
OBJECTIVES Our recent empirical findings have shown that the auditory nerve compound action potential (CAP) evoked by a low-level tone burst originates from a narrow cochlear region tuned to the tone burst frequency. At moderate to high sound levels, the origins shift to the most sensitive audiometric regions rather than the extended high-frequency regions of the cochlear base. This means that measurements evoked from extended high-frequency sound stimuli can shift toward the apex with increasing level. Here we translate this study to understand the spatial origin of acoustically evoked responses from ears that receive cochlear implants, an emerging area of research and clinical practice that is not completely understood. An essential step is to first understand the influence of the cochlear implant in otherwise naive ears. Our objective was to understand how function of the high-frequency cochlear base, which can be excited by the intense low-frequency sounds that are frequently used for objective intra- and postoperative monitoring, can be influenced by the presence of the cochlear implant. DESIGN We acoustically evoked responses and made measurements with an electrode placed near the guinea pig round window. The cochlear implant was not utilized for either electrical stimulation or recording purposes. With the cochlear implant in situ, CAPs were acoustically evoked from 2 to 16 kHz tone bursts of various levels while utilizing the slow perfusion of a kainic acid solution from the cochlear apex to the cochlear aqueduct in the base, which sequentially reduced neural responses from finely spaced cochlear frequency regions. This cochlear perfusion technique reveals the spatial origin of evoked potential measurements and provides insight on what influence the presence of an implant has on acoustical hearing. RESULTS Threshold measurements at 3 to 11 kHz were elevated by implantation. In an individual ear, thresholds were elevated and lowered as cochlear implant was respectively inserted and removed, indicative of "conductive hearing loss" induced by the implant. The maximum threshold elevation occurred at most sensitive region of the naive guinea pig ear (33.66 dB at 8 kHz), making 11 kHz the most sensitive region to acoustic sounds for guinea pig ears with cochlear implants. Conversely, the acute implantation did not affect the low-frequency, 500 Hz thresholds and suprathreshold function, as shown by the auditory nerve overlapped waveform. As the sound pressure level of the tone bursts increased, mean data show that the spatial origin of CAPs along the cochlear length shifted toward the most sensitive cochlear region of implanted ears, not the extended high-frequency cochlear regions. However, data from individual ears showed that after implantation, measurements from moderate to high sound pressure levels originate in places that are unique to each ear. CONCLUSIONS Alterations to function of the cochlear base from the in situ cochlear implant may influence objective measurements of implanted ears that are frequently made with intense low-frequency sound stimuli. Our results from guinea pigs advance the interpretation of measurements used to understand how and when residual acoustic hearing is lost in human ears receiving a cochlear implant.
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Affiliation(s)
- Choongheon Lee
- Department of Otolaryngology, University of Rochester, Rochester, New York, USA
| | - Jared J Hartsock
- Department of Cochlear Surgery, Turner Scientific, Inc., Jacksonville, Illinois, USA
| | - Alec N Salt
- Department of Pharmacokinetics, Turner Scientific, Inc., Jacksonville, Illinois, USA
| | - Jeffery T Lichtenhan
- Department of Otolaryngology, University of South Florida Morsani School of Medicine, Tampa, Florida, USA
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9
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Thompson NJ, Dillon MT, Nix EP, Overton AB, Selleck AM, Dedmon MM, Brown KD. Variables Affecting Cochlear Implant Performance After Loss of Residual Hearing. Laryngoscope 2024; 134:1868-1873. [PMID: 37767794 DOI: 10.1002/lary.31066] [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: 02/13/2023] [Revised: 08/15/2023] [Accepted: 09/12/2023] [Indexed: 09/29/2023]
Abstract
OBJECTIVE Determine variables that influence post-activation performance for cochlear implant (CI) recipients who lost low-frequency acoustic hearing. METHODS A retrospective review evaluated CNC word recognition for adults with normal to moderately severe low-frequency hearing (preoperative unaided thresholds of ≤70 dB HL at 250 Hz) who were implanted between 2012 and 2021 at a tertiary academic center, lost functional acoustic hearing, and were fit with a CI-alone device. Performance scores were queried from the 1, 3, 6, 12, and 24-month post-activation visits. A linear mixed model evaluated the effects of age at implantation, array length (long vs. mid/short), and preoperative low-frequency hearing (normal to mild, moderate, and moderately severe) on speech recognition with a CI alone. RESULTS 113 patients met the inclusion criteria. There was a significant main effect of interval (p < 0.001), indicating improved word recognition post-activation despite loss of residual hearing. There were significant main effects of age (p = 0.029) and array length (p = 0.038), with no effect of preoperative low-frequency hearing (p = 0.171). There was a significant 2-way interaction between age and array length (p = 0.018), indicating that older adults with mid/short arrays performed more poorly than younger adults with long lateral wall arrays when functional acoustic hearing was lost. CONCLUSION CI recipients with preoperative functional low-frequency hearing experience a significant improvement in speech recognition with a CI alone as compared to preoperative performance-despite the loss of low-frequency hearing. Age and electrode array length may play a role in post-activation performance. These data have implications for the preoperative counseling and device selection for hearing preservation candidates. LEVEL OF EVIDENCE 4 Laryngoscope, 134:1868-1873, 2024.
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Affiliation(s)
- Nicholas J Thompson
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, U.S.A
| | - Margaret T Dillon
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, U.S.A
| | - Evan P Nix
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, U.S.A
| | - Andrea B Overton
- Audiology Department, UNC Health, Chapel Hill, North Carolina, U.S.A
| | - A Morgan Selleck
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, U.S.A
| | - Matthew M Dedmon
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, U.S.A
| | - Kevin D Brown
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, U.S.A
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10
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Du H, Li J, Chen Z, Gao Y, Yang X, Yuan S, Wang Q, Guo W, Chen W, Dai P, Yang S. Changes in hearing function and intracochlear morphology after electrode array insertion in minipigs. Acta Otolaryngol 2024; 144:159-167. [PMID: 38742731 DOI: 10.1080/00016489.2024.2341122] [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: 01/17/2024] [Accepted: 04/04/2024] [Indexed: 05/16/2024]
Abstract
BACKGROUND In temporal bone specimens from long-term cochlear implant users, foreign body response within the cochlea has been demonstrated. However, how hearing changes after implantation and fibrosis progresses within the cochlea is unknown. OBJECTIVES To investigate the short-term dynamic changes in hearing and cochlear histopathology in minipigs after electrode array insertion. MATERIAL AND METHODS Twelve minipigs were selected for electrode array insertion (EAI) and the Control. Hearing tests were performed preoperatively and on 0, 7, 14, and 28 day(s) postoperatively, and cochlear histopathology was performed after the hearing tests on 7, 14, and 28 days after surgery. RESULTS Electrode array insertion had a significant effect for the frequency range tested (1 kHz-20kHz). Exudation was evident one week after electrode array insertion; at four weeks postoperatively, a fibrous sheath formed around the electrode. At each time point, the endolymphatic hydrops was found; no significant changes in the morphology and packing density of the spiral ganglion neurons were observed. CONCLUSIONS AND SIGNIFICANCE The effect of electrode array insertion on hearing and intracochlear fibrosis was significant. The process of fibrosis and endolymphatic hydrops seemed to not correlate with the degree of hearing loss, nor did it affect spiral ganglion neuron integrity in the 4-week postoperative period.
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Affiliation(s)
- Haiqiao Du
- Senior Department of Otolaryngology-Head and Neck Surgery, the Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China
- State Key Laboratory of Hearing and Balance Science, Beijing, China
- National Clinical Research Center for Otolaryngologic Diseases, Beijing, China
- Key Laboratory of Hearing Science, Ministry of Education, Beijing, China
- Beijing Key Laboratory of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Jianan Li
- Senior Department of Otolaryngology-Head and Neck Surgery, the Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China
- State Key Laboratory of Hearing and Balance Science, Beijing, China
- National Clinical Research Center for Otolaryngologic Diseases, Beijing, China
- Key Laboratory of Hearing Science, Ministry of Education, Beijing, China
- Beijing Key Laboratory of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Zhifeng Chen
- Senior Department of Otolaryngology-Head and Neck Surgery, the Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China
- State Key Laboratory of Hearing and Balance Science, Beijing, China
- National Clinical Research Center for Otolaryngologic Diseases, Beijing, China
- Key Laboratory of Hearing Science, Ministry of Education, Beijing, China
- Beijing Key Laboratory of Hearing Impairment Prevention and Treatment, Beijing, China
- Department of Otolaryngology Head and Neck Surgery, The 940th Hospital of Joint Logistics Support Force of Chinese PLA, Lanzhou, China
| | - Yun Gao
- Kunming Institute of Zoology, The Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Xiao Yang
- Kunming Institute of Zoology, The Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Shuolong Yuan
- Senior Department of Otolaryngology-Head and Neck Surgery, the Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China
- State Key Laboratory of Hearing and Balance Science, Beijing, China
- National Clinical Research Center for Otolaryngologic Diseases, Beijing, China
- Key Laboratory of Hearing Science, Ministry of Education, Beijing, China
- Beijing Key Laboratory of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Qian Wang
- Senior Department of Otolaryngology-Head and Neck Surgery, the Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China
- State Key Laboratory of Hearing and Balance Science, Beijing, China
- National Clinical Research Center for Otolaryngologic Diseases, Beijing, China
- Key Laboratory of Hearing Science, Ministry of Education, Beijing, China
- Beijing Key Laboratory of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Weiwei Guo
- Senior Department of Otolaryngology-Head and Neck Surgery, the Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China
- State Key Laboratory of Hearing and Balance Science, Beijing, China
- National Clinical Research Center for Otolaryngologic Diseases, Beijing, China
- Key Laboratory of Hearing Science, Ministry of Education, Beijing, China
- Beijing Key Laboratory of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Wei Chen
- Senior Department of Otolaryngology-Head and Neck Surgery, the Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China
- State Key Laboratory of Hearing and Balance Science, Beijing, China
- National Clinical Research Center for Otolaryngologic Diseases, Beijing, China
- Key Laboratory of Hearing Science, Ministry of Education, Beijing, China
- Beijing Key Laboratory of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Pu Dai
- Senior Department of Otolaryngology-Head and Neck Surgery, the Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China
- State Key Laboratory of Hearing and Balance Science, Beijing, China
- National Clinical Research Center for Otolaryngologic Diseases, Beijing, China
- Key Laboratory of Hearing Science, Ministry of Education, Beijing, China
- Beijing Key Laboratory of Hearing Impairment Prevention and Treatment, Beijing, China
| | - Shiming Yang
- Senior Department of Otolaryngology-Head and Neck Surgery, the Sixth Medical Center of Chinese PLA General Hospital, Chinese PLA Medical School, Beijing, China
- State Key Laboratory of Hearing and Balance Science, Beijing, China
- National Clinical Research Center for Otolaryngologic Diseases, Beijing, China
- Key Laboratory of Hearing Science, Ministry of Education, Beijing, China
- Beijing Key Laboratory of Hearing Impairment Prevention and Treatment, Beijing, China
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11
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Wong EC, Lopez IA, Ishiyama A, Ishiyama G. Expression of Brain-Derived Neurotrophic Factor in Human Spiral Ganglia Neurons after Cochlear Implantation. Otol Neurotol 2024; 45:326-333. [PMID: 38238917 PMCID: PMC10922350 DOI: 10.1097/mao.0000000000004104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
BACKGROUND Brain-derived neurotrophic factor (BDNF) is an important factor in the development and neuroprotection of afferent auditory pathways. In this study, we investigated the expression of BDNF in the afferent auditory pathway after cochlear implantation (CI), hypothesizing that electrical stimulation after CI stimulates BDNF expression in the afferent auditory pathway. METHODS Archival human temporal bones from eight patients with a history of CI and five patients with normal hearing (ages 65-93 years old) were studied. Temporal bone specimens were immunoreacted with rabbit polyclonal antibodies against BDNF and mouse monoclonal antibodies against pan-neurofilaments. In cases of unilateral CI, the BDNF expression was compared with the contralateral unimplanted ear and normal temporal bones without hearing loss. RESULTS BDNF immunoreactivity (IR) localized to the spiral ganglion neurons (SGNs) somata and the surrounding satellite cells. BDNF-IR in the spiral ganglia was similar in the apical, middle, and basal hook regions. Neurofilament IR localized to SGN nerve fibers in both implanted and unimplanted cochleae. BDNF-IR in the SGN and satellite cells was significantly increased in the implanted specimens compared with the unimplanted specimens ( p < 0.05) and the normal hearing specimens ( p < 0.05). BDNF-IR expression was similar in the unimplanted cochlea and in the normal cochlea. BDNF protein expression was increased despite complete loss of the organ of Corti hair cells and supporting cells. Even in the cases of CI with a 6-mm first-generation electrode, BDNF expression was upregulated throughout the cochlea. CONCLUSIONS BDNF expression in the SGN appears to be upregulated by the electrical stimulation from CI. This study provides evidence that the electrical stimulation from CI may stimulate the expression of BDNF, playing a neuroprotective role in the rehabilitation of hearing in the deafened ear.
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Affiliation(s)
| | | | | | - Gail Ishiyama
- UCLA Department of Head and Neck Surgery
- UCLA Department of Neurology
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12
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Geerardyn A, Zhu M, Verhaert N, Quesnel AM. Intracochlear Trauma and Local Ossification Patterns Differ Between Straight and Precurved Cochlear Implant Electrodes. Otol Neurotol 2024; 45:245-255. [PMID: 38270168 PMCID: PMC10922381 DOI: 10.1097/mao.0000000000004102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2024]
Abstract
HYPOTHESIS Trauma to the osseous spiral lamina (OSL) or spiral ligament (SL) during cochlear implant (CI) insertion segregates with electrode type and induces localized intracochlear ossification and fibrosis. BACKGROUND The goal of atraumatic CI insertion is to preserve intracochlear structures, limit reactive intracochlear tissue formation, and preserve residual hearing. Previous qualitative studies hypothesized a localized effect of trauma on intracochlear tissue formation; however, quantitative studies failed to confirm this. METHODS Insertional trauma beyond the immediate insertion site was histologically assessed in 21 human temporal bones with a CI. Three-dimensional reconstructions were generated and virtually resectioned perpendicular to the cochlear spiral at high resolution. The cochlear volume occupied by ossification or fibrosis was determined at the midpoint of the trauma and compared with regions proximal and distal to this point. RESULTS Seven cases, all implanted with precurved electrodes, showed an OSL fracture beyond the immediate insertion site. Significantly more intracochlear ossification was observed at the midpoint of the OSL fracture, compared with the -26 to -18 degrees proximal and 28 to 56 degrees distal to the center. No such pattern was observed for fibrosis. In the 12 cases with a perforation of the SL (9 straight and 3 precurved electrodes), no localized pattern of ossification or fibrosis was observed around these perforations. CONCLUSION OSL fractures were observed exclusively with precurved electrodes in this study and may serve as a nidus for localized intracochlear ossification. Perforation of the SL, in contrast, predominantly occurred with straight electrodes and was not associated with localized ossification.
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Affiliation(s)
| | - MengYu Zhu
- Otopathology Laboratory, Massachusetts Eye and Ear, Boston, Massachusetts, USA
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13
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Geerardyn A, Zhu M, Klabbers T, Huinck W, Mylanus E, Nadol JB, Verhaert N, Quesnel AM. Human Histology after Structure Preservation Cochlear Implantation via Round Window Insertion. Laryngoscope 2024; 134:945-953. [PMID: 37493203 DOI: 10.1002/lary.30900] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 06/22/2023] [Accepted: 07/05/2023] [Indexed: 07/27/2023]
Abstract
OBJECTIVES Current surgical techniques aim to preserve intracochlear structures during cochlear implant (CI) insertion to maintain residual cochlear function. The optimal technique to minimize damage, however, is still under debate. The aim of this study is to histologically compare insertional trauma and intracochlear tissue formation in humans with a CI implanted via different insertion techniques. METHODS One recent temporal bone from a donor who underwent implantation of a full-length CI (576°) via round window (RW) insertion was compared with nine cases implanted via cochleostomy (CO) or extended round window (ERW) approach. Insertional trauma was assessed on H&E-stained histological sections. 3D reconstructions were generated and virtually re-sectioned to measure intracochlear volumes of fibrosis and neo-ossification. RESULTS The RW insertion case showed electrode translocation via the spiral ligament. 2/9 CO/ERW cases showed no insertional trauma. The total volume of the cochlea occupied by fibro-osseous tissue was 10.8% in the RW case compared with a mean of 30.6% (range 8.7%-44.8%, N = 9) in the CO/ERW cases. The difference in tissue formation in the basal 5 mm of scala tympani, however, was even more pronounced when the RW case (12.3%) was compared with the cases with a CO/ERW approach (mean of 93.8%, range 81% to 100%, N = 9). CONCLUSIONS Full-length CI insertions via the RW can be minimally traumatic at the cochlear base without inducing extensive fibro-osseous tissue formation locally. The current study further supports the hypothesis that drilling of the cochleostomy with damage to the endosteum incites a local tissue reaction. LEVEL OF EVIDENCE 4: Case-control study Laryngoscope, 134:945-953, 2024.
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Affiliation(s)
- Alexander Geerardyn
- Department of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, Massachusetts, U.S.A
- Otopathology Laboratory, Massachusetts Eye and Ear, Boston, Massachusetts, U.S.A
- ExpORL, Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - MengYu Zhu
- Otopathology Laboratory, Massachusetts Eye and Ear, Boston, Massachusetts, U.S.A
| | - Tim Klabbers
- Department of Otorhinolaryngology, Radboudumc, Nijmegen, the Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Nijmegen, the Netherlands
| | - Wendy Huinck
- Department of Otorhinolaryngology, Radboudumc, Nijmegen, the Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Nijmegen, the Netherlands
| | - Emmanuel Mylanus
- Department of Otorhinolaryngology, Radboudumc, Nijmegen, the Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Nijmegen, the Netherlands
| | - Joseph B Nadol
- Department of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, Massachusetts, U.S.A
- Otopathology Laboratory, Massachusetts Eye and Ear, Boston, Massachusetts, U.S.A
| | - Nicolas Verhaert
- ExpORL, Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Alicia M Quesnel
- Department of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, Massachusetts, U.S.A
- Otopathology Laboratory, Massachusetts Eye and Ear, Boston, Massachusetts, U.S.A
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14
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Xu M, Chen A, Chen D, Wu S, Deng Z, Wen H, Zhong H, Lu K, Tang J, Ma D, Zhang H. Preparation, characterization, and in vitro/vivo evaluation of a multifunctional electrode coating for cochlear implants. BIOMATERIALS ADVANCES 2024; 157:213736. [PMID: 38128170 DOI: 10.1016/j.bioadv.2023.213736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 11/11/2023] [Accepted: 12/14/2023] [Indexed: 12/23/2023]
Abstract
Cochlear implantation (CI) is the primary intervention for patients with sensorineural hearing loss to restore their hearing. However, approximately 90 % of CI recipients experience unexpected fibrosis around the inserted electrode arrays due to acute and chronic inflammation. This fibrosis leads to progressive residual hearing loss. Addressing this complication is crucial for enhancing CI outcomes, yet an effective treatment has not yet been found. In this study, we developed a multifunctional dexamethasone (DXM)-loaded polytrimethylene carbonate (PTMC) electrode coating to mitigate inflammatory reactions and fibrosis after CI. This thin and flexible coating could preserve the mechanical performance of the electrode and reduce the implantation resistance for CI. The in vitro release studies demonstrated the DXM-PTMC coating's efficient drug loading and sustained release capability over 90 days. DXM-PTMC also showed long-term stability, high biocompatibility, and effective anti-inflammatory effects in vitro and in vivo. Compared with the uncoated group, DXM-PTMC coating significantly inhibited the expression of inflammatory factors, such as NO, TNF-α, IL-1β, and IL-6. DXM-PTMC coating suppressed fibrosis in rat implantation models for 3 weeks by reducing both acute and chronic inflammation. Our findings suggest that DXM-PTMC coating is a novel strategy to improve the outcomes of CI.
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Affiliation(s)
- Muqing Xu
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China; Ear Research Institute, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China
| | - Anning Chen
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China; Ear Research Institute, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China
| | - Dongxiu Chen
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China; Ear Research Institute, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China
| | - Shengquan Wu
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China
| | - Zhipeng Deng
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China
| | - Hang Wen
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China
| | - Huiling Zhong
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China
| | - Kejin Lu
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China
| | - Jie Tang
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China; Ear Research Institute, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China; Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China; Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou 510515, China.
| | - Dong Ma
- Guangdong Provincial Engineering and Technological Research Center for Drug Carrier Development, Key Laboratory of Biomaterials of Guangdong Higher Education Institutes, Department of Biomedical Engineering, Jinan University, Guangzhou 510632, China.
| | - Hongzheng Zhang
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China; Ear Research Institute, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China.
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15
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Kashani RG, Henslee A, Nelson RF, Hansen MR. Robotic assistance during cochlear implantation: the rationale for consistent, controlled speed of electrode array insertion. Front Neurol 2024; 15:1335994. [PMID: 38318440 PMCID: PMC10839068 DOI: 10.3389/fneur.2024.1335994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Accepted: 01/05/2024] [Indexed: 02/07/2024] Open
Abstract
Cochlear implants (CI) have revolutionized the treatment of patients with severe to profound sensory hearing loss by providing a method of bypassing normal hearing to directly stimulate the auditory nerve. A further advance in the field has been the introduction of "hearing preservation" surgery, whereby the CI electrode array (EA) is carefully inserted to spare damage to the delicate anatomy and function of the cochlea. Preserving residual function of the inner ear allows patients to receive maximal benefit from the CI and to combine CI electric stimulation with acoustic hearing, offering improved postoperative speech, hearing, and quality of life outcomes. However, under the current paradigm of implant surgery, where EAs are inserted by hand, the cochlea cannot be reliably spared from damage. Robotics-assisted EA insertion is an emerging technology that may overcome fundamental human kinetic limitations that prevent consistency in achieving steady and slow EA insertion. This review begins by describing the relationship between EA insertion speed and generation of intracochlear forces and pressures. The various mechanisms by which these intracochlear forces can damage the cochlea and lead to worsened postoperative outcomes are discussed. The constraints of manual insertion technique are compared to robotics-assisted methods, followed by an overview of the current and future state of robotics-assisted EA insertion.
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Affiliation(s)
- Rustin G. Kashani
- Department of Otolaryngology – Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA, United States
| | | | | | - Marlan R. Hansen
- Department of Otolaryngology – Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA, United States
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16
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Derdzakyan NA, Lava CX, Hakimi AA, Johns JD, Kim HJ, Hoa M. Variability in Perioperative Steroid Therapy Regimen for Cochlear Implantation as It Relates to Hearing Preservation. Otol Neurotol 2024; 45:e28-e35. [PMID: 38085763 DOI: 10.1097/mao.0000000000004058] [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: 12/18/2023]
Abstract
HYPOTHESIS We aimed to identify practice trends and association between physician training and administration of perioperative steroids for cochlear implantation (CI) as it relates to hearing preservation. BACKGROUND Perioperative steroid therapy regimens are postulated to protect residual hearing and improve hearing preservation outcomes in CI. METHODS A 27-question online survey was developed by the senior authors using the Qualtrics Survey Tool, then distributed via email from September to November 2022 to otolaryngologists specializing in otology or neurotology and who practice in the United States or Canada. RESULTS The survey was sent to 463 physicians, 162 (35.0%) of whom completed the survey. One hundred forty-four (31.1%) responses underwent analysis. All physicians administering preoperative steroids (n = 31) prefer preoperative oral prednisone. Of 143 physicians administering intraoperative steroids, 54.5% prefer intraoperative intravenous dexamethasone. More than half (77.6%) of 85 physicians administering postoperative steroids prefer postoperative oral prednisone. Postoperative steroid administration (p < 0.006) and taper utilization (p < 0.041) were greater among physicians who complete greater than 40 CIs annually (n = 47 [71.2%]; n = 30 [49.2%]) than physicians who complete up to 40 CIs annually (n = 37 [48.7%]; n = 20 [31.3%]), respectively. Physicians practicing for 5 to 20 years after residency are more prevalent in using postoperative steroid tapers than physicians practicing for fewer than 5 years after and more than 20 years after residency (n = 37 [51.4%] versus n = 14 [25.5%], p < 0.001). CONCLUSION Consensus is needed about the optimal steroid treatment for CI patients. LEVEL OF EVIDENCE 4.
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Affiliation(s)
| | | | - Amir A Hakimi
- Department of Otolaryngology-Head and Neck Surgery, Georgetown University Medical Center, Washington, DC
| | - J Dixon Johns
- Department of Otolaryngology-Head and Neck Surgery, Georgetown University Medical Center, Washington, DC
| | - H Jeffrey Kim
- Department of Otolaryngology-Head and Neck Surgery, Georgetown University Medical Center, Washington, DC
| | - Michael Hoa
- Department of Otolaryngology-Head and Neck Surgery, Georgetown University Medical Center, Washington, DC
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17
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Rahman MT, Mostaert BJ, Hunger B, Saha U, Claussen AD, Razu I, Nasrin F, Khan NA, Eckard P, Coleman S, Oleson J, Kirk JR, Hirose K, Hansen MR. Contribution of macrophages to neural survival and intracochlear tissue remodeling responses following cochlear implantation. J Neuroinflammation 2023; 20:266. [PMID: 37974203 PMCID: PMC10652501 DOI: 10.1186/s12974-023-02955-y] [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: 06/12/2023] [Accepted: 11/10/2023] [Indexed: 11/19/2023] Open
Abstract
BACKGROUND Cochlear implants (CIs) restore hearing to deafened patients. The foreign body response (FBR) following cochlear implantation (post-CI) comprises an infiltration of macrophages, other immune and non-immune cells, and fibrosis into the scala tympani, a space that is normally devoid of cells. This FBR is associated with negative effects on CI outcomes including increased electrode impedances and loss of residual acoustic hearing. This study investigates the extent to which macrophage depletion by an orally administered CSF-1R specific kinase (c-FMS) inhibitor, PLX-5622, modulates the tissue response to CI and neural health. MAIN TEXT 10- to 12-week-old CX3CR1 + /GFP Thy1 + /YFP mice on C57BL/6J/B6 background was fed chow containing 1200 mg/kg PLX5622 or control chow for the duration of the study. 7 days after starting the diet, 3-channel cochlear implants were implanted in the ear via the round window. Serial impedance and neural response telemetry (NRT) measurements were acquired throughout the study. Electric stimulation began 7 days post-CI until 28 days post-CI for 5 h/day, 5 days/week, with programming guided by NRT and behavioral responses. Cochleae harvested at 10, 28 or 56 days post-CI were cryosectioned and labeled with an antibody against α-smooth muscle actin (α-SMA) to identify myofibroblasts and quantify the fibrotic response. Using IMARIS image analysis software, the outlines of scala tympani, Rosenthal canal, modiolus, and lateral wall for each turn were traced manually to measure region volume. The density of nuclei, CX3CR1 + macrophages, Thy1 + spiral ganglion neuron (SGN) numbers, and the ratio of the α-SMA + volume/scala tympani volume were calculated. Cochlear implantation in control diet subjects caused infiltration of cells, including macrophages, into the cochlea. Fibrosis was evident in the scala tympani adjacent to the electrode array. Mice fed PLX5622 chow showed reduced macrophage infiltration throughout the implanted cochleae across all time points. However, scala tympani fibrosis was not reduced relative to control diet subjects. Further, mice treated with PLX5622 showed increased electrode impedances compared to controls. Finally, treatment with PLX5622 decreased SGN survival in implanted and contralateral cochleae. CONCLUSION The data suggest that macrophages play an important role in modulating the intracochlear tissue response following CI and neural survival.
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Affiliation(s)
- Muhammad Taifur Rahman
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Brian J Mostaert
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Bryce Hunger
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Utsow Saha
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Alexander D Claussen
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Ibrahim Razu
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Farjana Nasrin
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Nashwaan Ali Khan
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Peter Eckard
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Sarah Coleman
- Department of Biostatistics, The University of Iowa, Iowa City, IA, USA
| | - Jacob Oleson
- Department of Biostatistics, The University of Iowa, Iowa City, IA, USA
| | | | - Keiko Hirose
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO, USA
| | - Marlan R Hansen
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA.
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18
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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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19
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Braack KJ, Miles T, Amat F, Brown DJ, Atlas MD, Kuthubutheen J, Mulders WH, Prêle CM. Using x-ray micro computed tomography to quantify intracochlear fibrosis after cochlear implantation in a Guinea pig model. Heliyon 2023; 9:e19343. [PMID: 37662829 PMCID: PMC10474428 DOI: 10.1016/j.heliyon.2023.e19343] [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: 02/23/2023] [Revised: 08/07/2023] [Accepted: 08/18/2023] [Indexed: 09/05/2023] Open
Abstract
Cochlear implants (CIs) allow individuals with profound hearing loss to understand speech and perceive sounds. However, not all patients obtain the full benefits that CIs can provide and the cause of this disparity is not fully understood. One possible factor for the variability in outcomes after cochlear implantation, is the development of fibrotic scar tissue around the implanted electrode. It has been hypothesised that limiting the extent of fibrosis after implantation may improve overall CI function, and longevity of the device. Currently, histology is often used to quantify the extent of intracochlear tissue growth after implantation however this method is labour intensive, time-consuming, often involves significant user bias, and causes physical distortion of the fibrosis. Therefore, this study aimed to evaluate x-ray micro computed tomography (μCT) as a method to measure the amount and distribution of fibrosis in a guinea pig model of cochlear implantation. Adult guinea pigs were implanted with an inactive electrode, and cochleae harvested eight weeks later (n = 7) and analysed using μCT, to quantify the extent of tissue reaction, followed by histological analysis to confirm that the tissue was indeed fibrotic. Cochleae harvested from an additional six animals following implantation were analysed by μCT, before and after contrast staining with osmium tetroxide (OsO4), to enhance the visualisation of soft tissues within the cochlea, including the tissue reaction. Independent analysis by two observers showed that the quantification method was robust and provided additional information on the distribution of the response within the cochlea. Histological analysis revealed that μCT visualised dense collagenous material and new bone formation but did not capture loose, areolar fibrotic tissue. Treatment with OsO4 significantly enhanced the visible tissue reaction detected using μCT. Overall, μCT is an alternative and reliable method that can be used to quantify the extent of the CI-induced intracochlear tissue response and will be a useful tool for the in vivo assessment of novel anti-fibrotic treatments.
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Affiliation(s)
- Kady J. Braack
- School of Human Sciences, University of Western Australia, Crawley, WA 6009, Australia
| | - Tylah Miles
- Institute for Respiratory Health, University of Western Australia, Nedlands, WA 6009, Australia
| | - Farah Amat
- School of Human Sciences, University of Western Australia, Crawley, WA 6009, Australia
| | - Daniel J. Brown
- Curtin Medical School, Curtin University, Bentley, WA 6102, Australia
| | - Marcus D. Atlas
- Curtin Medical School, Curtin University, Bentley, WA 6102, Australia
- Medical School, University of Western Australia, Crawley, WA 6009, Australia
- Ear Science Institute Australia, Subiaco, WA 6008, Australia
| | - Jafri Kuthubutheen
- Medical School, University of Western Australia, Crawley, WA 6009, Australia
- Department of Otolaryngology Head and Neck Surgery, Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, WA 6009, Australia
| | | | - Cecilia M. Prêle
- Institute for Respiratory Health, University of Western Australia, Nedlands, WA 6009, Australia
- Ear Science Institute Australia, Subiaco, WA 6008, Australia
- School of Medical, Molecular and Forensic Sciences, Murdoch University, Murdoch, WA 6150, Australia
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20
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Tejani VD, Kim JS, Etler CP, Skidmore J, Yuan Y, He S, Hansen MR, Gantz BJ, Abbas PJ, Brown CJ. Longitudinal Electrocochleography as an Objective Measure of Serial Behavioral Audiometry in Electro-Acoustic Stimulation Patients. Ear Hear 2023; 44:1014-1028. [PMID: 36790447 PMCID: PMC10425573 DOI: 10.1097/aud.0000000000001342] [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: 02/16/2023]
Abstract
OBJECTIVE Minimally traumatic surgical techniques and advances in cochlear implant (CI) electrode array designs have allowed acoustic hearing present in a CI candidate prior to surgery to be preserved postoperatively. As a result, these patients benefit from combined electric-acoustic stimulation (EAS) postoperatively. However, 30% to 40% of EAS CI users experience a partial loss of hearing up to 30 dB after surgery. This additional hearing loss is generally not severe enough to preclude use of acoustic amplification; however, it can still impact EAS benefits. The use of electrocochleography (ECoG) measures of peripheral hair cell and neural auditory function have shed insight into the pathophysiology of postimplant loss of residual acoustic hearing. The present study aims to assess the long-term stability of ECoG measures and to establish ECoG as an objective method of monitoring residual hearing over the course of EAS CI use. We hypothesize that repeated measures of ECoG should remain stable over time for EAS CI users with stable postoperative hearing preservation. We also hypothesize that changes in behavioral audiometry for EAS CI users with loss of residual hearing should also be reflected in changes in ECoG measures. DESIGN A pool of 40 subjects implanted under hearing preservation protocol was included in the study. Subjects were seen at postoperative visits for behavioral audiometry and ECoG recordings. Test sessions occurred 0.5, 1, 3, 6, 12 months, and annually after 12 months postoperatively. Changes in pure-tone behavioral audiometric thresholds relative to baseline were used to classify subjects into two groups: one group with stable acoustic hearing and another group with loss of acoustic hearing. At each test session, ECoG amplitude growth functions for several low-frequency stimuli were obtained. The threshold, slope, and suprathreshold amplitude at a fixed stimulation level was obtained from each growth function at each time point. Longitudinal linear mixed effects models were used to study trends in ECoG thresholds, slopes, and amplitudes for subjects with stable hearing and subjects with hearing loss. RESULTS Preoperative, behavioral audiometry indicated that subjects had an average low-frequency pure-tone average (125 to 500 Hz) of 40.88 ± 13.12 dB HL. Postoperatively, results showed that ECoG thresholds and amplitudes were stable in EAS CI users with preserved residual hearing. ECoG thresholds increased (worsened) while ECoG amplitudes decreased (worsened) for those with delayed hearing loss. The slope did not distinguish between EAS CI users with stable hearing and subjects with delayed loss of hearing. CONCLUSIONS These results provide a new application of postoperative ECoG as an objective tool to monitor residual hearing and understand the pathophysiology of delayed hearing loss. While our measures were conducted with custom-designed in-house equipment, CI companies are also designing and implementing hardware and software adaptations to conduct ECoG recordings. Thus, postoperative ECoG recordings can potentially be integrated into clinical practice.
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Affiliation(s)
- Viral D Tejani
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals Cleveland Medical Center, Cleveland, Ohio, USA
- Department of Otolaryngology-Head and Neck Surgery, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
- Department of Communication Sciences and Disorders, University of Iowa, Iowa City, Iowa, USA
| | - Jeong-Seo Kim
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
- Department of Communication Sciences and Disorders, University of Iowa, Iowa City, Iowa, USA
- Hearing Research Laboratory, Samsung Medical Center, Seoul, South Korea
| | - Christine P Etler
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | - Jeffrey Skidmore
- Department of Otolaryngology-Head and Neck Surgery, Eye and Ear Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Yi Yuan
- Department of Otolaryngology-Head and Neck Surgery, Eye and Ear Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Shuman He
- Department of Otolaryngology-Head and Neck Surgery, Eye and Ear Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Marlan R Hansen
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
- Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
- Department of Molecular Physiology and Biophysics, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | - Bruce J Gantz
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
- Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
| | - Paul J Abbas
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
- Department of Communication Sciences and Disorders, University of Iowa, Iowa City, Iowa, USA
| | - Carolyn J Brown
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
- Department of Communication Sciences and Disorders, University of Iowa, Iowa City, Iowa, USA
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21
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Horne R, Ben-Shlomo N, Jensen M, Ellerman M, Escudero C, Hua R, Bennion D, Guymon CA, Hansen MR. Reducing the foreign body response on human cochlear implants and their materials in vivo with photografted zwitterionic hydrogel coatings. Acta Biomater 2023; 166:212-223. [PMID: 37187301 PMCID: PMC10330692 DOI: 10.1016/j.actbio.2023.05.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 04/27/2023] [Accepted: 05/04/2023] [Indexed: 05/17/2023]
Abstract
The foreign body response to implanted materials often complicates the functionality of sensitive biomedical devices. For cochlear implants, this response can reduce device performance, battery life and preservation of residual acoustic hearing. As a permanent and passive solution to the foreign body response, this work investigates ultra-low-fouling poly(carboxybetaine methacrylate) (pCBMA) thin film hydrogels that are simultaneously photo-grafted and photo-polymerized onto polydimethylsiloxane (PDMS). The cellular anti-fouling properties of these coatings are robustly maintained even after six-months subcutaneous incubation and over a broad range of cross-linker compositions. On pCBMA-coated PDMS sheets implanted subcutaneously, capsule thickness and inflammation are reduced significantly in comparison to uncoated PDMS or coatings of polymerized poly(ethylene glycol dimethacrylate) (pPEGDMA). Further, capsule thickness is reduced over a wide range of pCBMA cross-linker compositions. On cochlear implant electrode arrays implanted subcutaneously for one year, the coating bridges over the exposed platinum electrodes and dramatically reduces the capsule thickness over the entire implant. Coated cochlear implant electrode arrays could therefore lead to persistent improved performance and reduced risk of residual hearing loss. More generally, the in vivo anti-fibrotic properties of pCBMA coatings also demonstrate potential to mitigate the fibrotic response on a variety of sensing/stimulating implants. STATEMENT OF SIGNIFICANCE: This article presents, for the first time, evidence of the in vivo anti-fibrotic effect of zwitterionic hydrogel thin films photografted to polydimethylsiloxane (PDMS) and human cochlear implant arrays. The hydrogel coating shows no evidence of degradation or loss of function after long-term implantation. The coating process enables full coverage of the electrode array. The coating reduces fibrotic capsule thickness 50-70% over a broad range of cross-link densities for implantations from six weeks to one year.
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Affiliation(s)
- Ryan Horne
- University of Iowa Carver College of Medicine, United States of America; University of Iowa Department of Chemical and Biochemical Engineering, United States of America
| | - Nir Ben-Shlomo
- University of Iowa Hospitals and Clinics Department of Otolaryngology, United States of America
| | - Megan Jensen
- University of Iowa Hospitals and Clinics Department of Otolaryngology, United States of America
| | - Morgan Ellerman
- University of Iowa Department of Chemical and Biochemical Engineering, United States of America
| | - Caleb Escudero
- University of Iowa Carver College of Medicine, United States of America
| | - Rong Hua
- University of Iowa Hospitals and Clinics Department of Otolaryngology, United States of America
| | - Douglas Bennion
- University of Iowa Hospitals and Clinics Department of Otolaryngology, United States of America
| | - C Allan Guymon
- University of Iowa Department of Chemical and Biochemical Engineering, United States of America
| | - Marlan R Hansen
- University of Iowa Hospitals and Clinics Department of Otolaryngology, United States of America.
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22
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Rahman MT, Mostaert BJ, Hunger B, Saha U, Claussen AD, Razu I, Farjana N, Khan NA, Coleman S, Oleson J, Kirk J, Keiko H, Hansen MR. Contribution of macrophages to intracochlear tissue remodeling responses following cochlear implantation and neural survival. RESEARCH SQUARE 2023:rs.3.rs-3065630. [PMID: 37461619 PMCID: PMC10350110 DOI: 10.21203/rs.3.rs-3065630/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/24/2023]
Abstract
Introduction Cochlear implants (CIs) restore hearing to deafened patients. The foreign body response (FBR) following cochlear implantation (post-CI) comprises an infiltration of macrophages, other immune and non-immune cells, and fibrosis into the scala tympani; a space that is normally devoid of cells. This FBR is associated with negative effects on CI outcomes including increased electrode impedances and loss of residual acoustic hearing. This study investigates the extent to which macrophage depletion by an orally administered CSF-1R specific kinase (c-FMS) inhibitor, PLX-5622, modulates the tissue response to CI and neural health. Materials and methods 10-12-week-old CX3CR1+/GFP Thy1+/YFP mice on C57Bl6 background with normal hearing were fed chow containing 1200 mg/kg PLX5622 or control chow for the duration of the study. 7-days after starting the diet, 3-channel cochlear implants were implanted ear via the round window. Serial impedance and neural response telemetry (NRT) measurements were acquired throughout the study. Electric stimulation began 7 days post-CI until 28- days post-CI for 5 hrs/day, 5 days/week, with programming guided by NRT and behavioral responses. Cochleae harvested at 10-, 28- or 56-days post-CI were cryosectioned and labeled with antibody against α-smooth muscle actin (α-SMA) to identify myofibroblasts and quantify the fibrotic response. Using IMARIS image analysis software, the outlines of scala tympani, Rosenthal canal, modiolus and lateral wall for each turn were traced manually to measure region volume. Density of nuclei, CX3CR1+ macrophages, Thy1+ spiral ganglion neuron (SGN) numbers and ratio of volume of α-SMA+ space/volume of scala tympani were calculated. Results Cochlear implantation in control diet subjects caused infiltration of cells, including macrophages, into the cochlea: this response was initially diffuse throughout the cochlea and later localized to the scala tympani of the basal turn by 56-days post-CI. Fibrosis was evident in the scala tympani adjacent to the electrode array. Mice fed PLX5622 chow showed reduced macrophage infiltration throughout the implanted cochleae across all timepoints. However, scala tympani fibrosis was not reduced relative to control diet subjects. Further, mice treated with PLX5622 showed increased electrode impedances compared to controls. Finally, treatment with PLX5622 decreased SGN survival in implanted and contralateral cochleae. Discussion The data suggest that macrophages play an important role in modulating the intracochlear tissue response following CI and neural survival.
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Affiliation(s)
| | - Brain J Mostaert
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Bryce Hunger
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Utsow Saha
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | | | - Ibrahim Razu
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Nasrin Farjana
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Nashwaan Ali Khan
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Sarah Coleman
- Department of Statistics, The University of Iowa, IA
| | - Jackob Oleson
- Department of Statistics, The University of Iowa, IA
| | | | - Hirose Keiko
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St Louis, MO
| | - Marlan R Hansen
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
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23
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Schraivogel S, Aebischer P, Weder S, Caversaccio M, Wimmer W. Cochlear implant electrode impedance subcomponents as biomarker for residual hearing. Front Neurol 2023; 14:1183116. [PMID: 37288065 PMCID: PMC10242064 DOI: 10.3389/fneur.2023.1183116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 04/25/2023] [Indexed: 06/09/2023] Open
Abstract
Introduction and objectives Maintaining the structural integrity of the cochlea and preserving residual hearing is crucial for patients, especially for those for whom electric acoustic stimulation is intended. Impedances could reflect trauma due to electrode array insertion and therefore could serve as a biomarker for residual hearing. The aim of this study is to evaluate the association between residual hearing and estimated impedance subcomponents in a known collective from an exploratory study. Methods A total of 42 patients with lateral wall electrode arrays from the same manufacturer were included in the study. For each patient, we used data from audiological measurements to compute residual hearing, impedance telemetry recordings to estimate near and far-field impedances using an approximation model, and computed tomography scans to extract anatomical information about the cochlea. We assessed the association between residual hearing and impedance subcomponent data using linear mixed-effects models. Results The progression of impedance subcomponents showed that far-field impedance was stable over time compared to near-field impedance. Low-frequency residual hearing demonstrated the progressive nature of hearing loss, with 48% of patients showing full or partial hearing preservation after 6 months of follow-up. Analysis revealed a statistically significant negative effect of near-field impedance on residual hearing (-3.81 dB HL per kΩ; p < 0.001). No significant effect of far-field impedance was found. Conclusion Our findings suggest that near-field impedance offers higher specificity for residual hearing monitoring, while far-field impedance was not significantly associated with residual hearing. These results highlight the potential of impedance subcomponents as objective biomarkers for outcome monitoring in cochlear implantation.
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Affiliation(s)
- Stephan Schraivogel
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
- Department of ENT—Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Philipp Aebischer
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
- Department of ENT—Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Stefan Weder
- Department of ENT—Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Marco Caversaccio
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
- Department of ENT—Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Wilhelm Wimmer
- Department of ENT—Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Department of Otorhinolaryngology, TUM School of Medicine, Klinikum Rechts der Isar, Technical University of Munich, Munich, Germany
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24
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Kirk JR, Smyth D, Dueck WF. A new paradigm of hearing loss and preservation with cochlear implants: Learnings from fundamental studies and clinical research. Hear Res 2023; 433:108769. [PMID: 37120894 DOI: 10.1016/j.heares.2023.108769] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 02/18/2023] [Accepted: 04/15/2023] [Indexed: 05/02/2023]
Abstract
In 2010 Cochlear initiated a coordinated preclinical research program to identify the factors and underlying mechanisms of acoustic hearing loss following cochlear implantation and device use. At its inception the program was structured around several major hypotheses implicated in the loss of acoustic hearing. The understanding of causes evolved over the course of the program, leading to an increased appreciation of the role of the biological response in post-implant hearing loss. A systematic approach was developed which mapped the cochlear implant journey along a timeline that considers all events in an individual's hearing history. By evaluating the available data in this context, rather than by discrete hypothesis testing, causative and associated factors may be more readily detected. This approach presents opportunities for more effective research management and may aid in identifying new prospects for intervention. Many of the outcomes of the research program apply beyond preservation of acoustic hearing to factors important to overall cochlear health and considerations for future therapies.
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Affiliation(s)
- Jonathon R Kirk
- Cochlear Limited, 1 University Avenue, Macquarie University, NSW 2109, Australia.
| | - Daniel Smyth
- Cochlear Limited, 1 University Avenue, Macquarie University, NSW 2109, Australia
| | - Wolfram F Dueck
- Cochlear Limited, 1 University Avenue, Macquarie University, NSW 2109, Australia
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25
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Wellens J, Deschaume O, Putzeys T, Eyley S, Thielemans W, Verhaert N, Bartic C. Sulfobetaine-based ultrathin coatings as effective antifouling layers for implantable neuroprosthetic devices. Biosens Bioelectron 2023; 226:115121. [PMID: 36774733 DOI: 10.1016/j.bios.2023.115121] [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: 11/09/2022] [Revised: 01/30/2023] [Accepted: 02/02/2023] [Indexed: 02/05/2023]
Abstract
Foreign body response (FBR), inflammation, and fibrotic encapsulation of neural implants remain major problems affecting the impedance of the electrode-tissue interface and altering the device performance. Adhesion of proteins and cells (e.g., pro-inflammatory macrophages, and fibroblasts) triggers the FBR cascade and can be diminished by applying antifouling coatings onto the implanted devices. In this paper, we report the deposition and characterization of a thin (±6 nm) sulfobetaine-based coating onto microfabricated platinum electrodes and cochlear implant (CI) electrode arrays. We found that this coating has stable cell and protein-repellent properties, for at least 31 days in vitro, not affected by electrical stimulation protocols. Additionally, its effect on the electrochemical properties relevant to stimulation (i.e., impedance, charge injection capacity) was negligible. When applied to clinical CI electrode arrays, the film was successful at inhibiting fibroblast adhesion on both the silicone packaging and the platinum/iridium electrodes. In vitro, in fibroblast cultures, coated CI electrode arrays maintained impedance values up to five times lower compared to non-coated devices. Our studies demonstrate that such thin sulfobetaine containing layers are stable and prevent protein and cell adhesion in vitro and are compatible for use on CI electrode arrays. Future in vivo studies should be conducted to investigate its ability to mitigate biofouling, fibrosis, and the resulting impedance changes upon long-term implantation in vivo.
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Affiliation(s)
- Jolan Wellens
- Laboratory for Soft Matter and Biophysics, Dept. Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001, Leuven, Belgium
| | - Olivier Deschaume
- Laboratory for Soft Matter and Biophysics, Dept. Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001, Leuven, Belgium
| | - Tristan Putzeys
- Laboratory for Soft Matter and Biophysics, Dept. Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001, Leuven, Belgium; Experimental Oto-rhino-laryngology Research Group, Dept. Neuroscience, KU Leuven, Herestraat 49, 3000, Leuven, Belgium
| | - Samuel Eyley
- Sustainable Materials Lab, Department of Chemical Engineering, KU Leuven, Campus Kulak Kortrijk, Etienne Sabbelaan 53, 8500, Kortrijk, Belgium
| | - Wim Thielemans
- Sustainable Materials Lab, Department of Chemical Engineering, KU Leuven, Campus Kulak Kortrijk, Etienne Sabbelaan 53, 8500, Kortrijk, Belgium
| | - Nicolas Verhaert
- Experimental Oto-rhino-laryngology Research Group, Dept. Neuroscience, KU Leuven, Herestraat 49, 3000, Leuven, Belgium; Department of Otorhinolaryngology, University Hospitals Leuven, Herestraat 49, 3000, Leuven, Belgium
| | - Carmen Bartic
- Laboratory for Soft Matter and Biophysics, Dept. Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001, Leuven, Belgium.
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26
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Ishiyama P, Ishiyama G, Lopez IA, Ishiyama A. Archival Human Temporal Bone: Anatomical and Histopathological Studies of Cochlear Implantation. J Pers Med 2023; 13:352. [PMID: 36836587 PMCID: PMC9959196 DOI: 10.3390/jpm13020352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 02/12/2023] [Accepted: 02/14/2023] [Indexed: 02/22/2023] Open
Abstract
Since being FDA approved in 1984, cochlear implantation has been used successfully to restore hearing in those with severe to profound hearing loss with broader applications including single-sided deafness, the use of hybrid electroacoustic stimulation, and implantation at all extremes of age. Cochlear implants have undergone multiple changes in the design aimed at improving the processing technology, while simultaneously minimizing the surgical trauma and foreign body reaction. The following review examines the human temporal bone studies regarding the anatomy of the human cochlea and how the anatomy relates to cochlear implant design, the factors related to complications after implantation, and the predictors of new tissue formation and osteoneogenesis. Histopathological studies are reviewed which aim to understand the potential implications of the effects of new tissue formation and inflammation following implantation.
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Affiliation(s)
- Paul Ishiyama
- Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Gail Ishiyama
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Ivan A. Lopez
- Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Akira Ishiyama
- Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
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27
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Geerardyn A, Zhu M, Wu P, O'Malley J, Nadol JB, Liberman MC, Nakajima HH, Verhaert N, Quesnel AM. Three-dimensional quantification of fibrosis and ossification after cochlear implantation via virtual re-sectioning: Potential implications for residual hearing. Hear Res 2023; 428:108681. [PMID: 36584546 PMCID: PMC10942756 DOI: 10.1016/j.heares.2022.108681] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 12/13/2022] [Accepted: 12/18/2022] [Indexed: 12/24/2022]
Abstract
Hearing preservation may be achieved initially in the majority of patients after cochlear implantation, however, a significant proportion of these patients experience delayed hearing loss months or years later. A prior histological report in a case of delayed hearing loss suggested a potential cochlear mechanical origin of this hearing loss due to tissue fibrosis, and older case series highlight the frequent findings of post-implantation fibrosis and neoosteogenesis though without a focus on the impact on residual hearing. Here we present the largest series (N = 20) of 3-dimensionally reconstructed cochleae based on digitally scanned histologic sections from patients who were implanted during their lifetime. All patients were implanted with multichannel electrodes via a cochleostomy or an extended round window insertion. A quantified analysis of intracochlear tissue formation was carried out via virtual re-sectioning orthogonal to the cochlear spiral. Intracochlear tissue formation was present in every case. On average 33% (SD 14%) of the total cochlear volume was occupied by new tissue formation, consisting of 26% (SD 12%) fibrous and 7% (SD 6%) bony tissue. The round window was completely covered by fibro-osseous tissue in 85% of cases and was associated with an obstruction of the cochlear aqueduct in 100%. The basal part of the basilar membrane was at least partially abutted by the electrode or new tissue formation in every case, while the apical region, corresponding with a characteristic frequency of < 500 Hz, appeared normal in 89%. This quantitative analysis shows that after cochlear implantation via extended round window or cochleostomy, intracochlear fibrosis and neoossification are present in all cases at anatomical locations that could impact normal inner ear mechanics.
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Affiliation(s)
- A Geerardyn
- Department of Otolaryngology - Head & Neck Surgery, Harvard Medical School, Boston, MA, USA; Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, USA; ExpORL, Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - M Zhu
- Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, USA
| | - P Wu
- Department of Otolaryngology - Head & Neck Surgery, Harvard Medical School, Boston, MA, USA; Eaton Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA, USA
| | - J O'Malley
- Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, USA
| | - J B Nadol
- Department of Otolaryngology - Head & Neck Surgery, Harvard Medical School, Boston, MA, USA; Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, USA
| | - M C Liberman
- Department of Otolaryngology - Head & Neck Surgery, Harvard Medical School, Boston, MA, USA; Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, USA; Eaton Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA, USA
| | - H H Nakajima
- Department of Otolaryngology - Head & Neck Surgery, Harvard Medical School, Boston, MA, USA; Eaton Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA, USA
| | - N Verhaert
- ExpORL, Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - A M Quesnel
- Department of Otolaryngology - Head & Neck Surgery, Harvard Medical School, Boston, MA, USA; Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, USA.
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Schvartz-Leyzac KC, Colesa DJ, Swiderski DL, Raphael Y, Pfingst BE. Cochlear Health and Cochlear-implant Function. J Assoc Res Otolaryngol 2023; 24:5-29. [PMID: 36600147 PMCID: PMC9971430 DOI: 10.1007/s10162-022-00882-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 11/24/2022] [Indexed: 01/06/2023] Open
Abstract
The cochlear implant (CI) is widely considered to be one of the most innovative and successful neuroprosthetic treatments developed to date. Although outcomes vary, CIs are able to effectively improve hearing in nearly all recipients and can substantially improve speech understanding and quality of life for patients with significant hearing loss. A wealth of research has focused on underlying factors that contribute to success with a CI, and recent evidence suggests that the overall health of the cochlea could potentially play a larger role than previously recognized. This article defines and reviews attributes of cochlear health and describes procedures to evaluate cochlear health in humans and animal models in order to examine the effects of cochlear health on performance with a CI. Lastly, we describe how future biologic approaches can be used to preserve and/or enhance cochlear health in order to maximize performance for individual CI recipients.
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Affiliation(s)
- Kara C Schvartz-Leyzac
- Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, Kresge Hearing Research Institute, University of Michigan, 1150 Medical Center Drive, Ann Arbor, MI, 48109-5616, USA
- Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Ave, Charleston, SC, 29425, USA
| | - Deborah J Colesa
- Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, Kresge Hearing Research Institute, University of Michigan, 1150 Medical Center Drive, Ann Arbor, MI, 48109-5616, USA
| | - Donald L Swiderski
- Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, Kresge Hearing Research Institute, University of Michigan, 1150 Medical Center Drive, Ann Arbor, MI, 48109-5616, USA
| | - Yehoash Raphael
- Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, Kresge Hearing Research Institute, University of Michigan, 1150 Medical Center Drive, Ann Arbor, MI, 48109-5616, USA
| | - Bryan E Pfingst
- Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, Kresge Hearing Research Institute, University of Michigan, 1150 Medical Center Drive, Ann Arbor, MI, 48109-5616, USA.
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29
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Wackym PA, Balaban CD, Van Osch OJ, Morris BT, Tamakloe MA, Salvatore VL, Duwadi S, Gay JD, Mowery TM. New model of superior semicircular canal dehiscence with reversible diagnostic findings characteristic of patients with the disorder. Front Neurol 2023; 13:1035478. [PMID: 36742050 PMCID: PMC9892720 DOI: 10.3389/fneur.2022.1035478] [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: 09/02/2022] [Accepted: 11/15/2022] [Indexed: 01/20/2023] Open
Abstract
Background Third window syndrome is a vestibular-cochlear disorder in humans in which a third mobile window of the otic capsule creates changes to the flow of sound pressure energy through the perilymph/endolymph. The nature and location of this third mobile window can occur at many different sites (or multiple sites); however, the most common third mobile window is superior semicircular canal dehiscence (SSCD). There are two essential objective diagnostic characteristics needed to validate a model of SSCD: the creation of a pseudoconductive hearing loss and cVEMP increased amplitude and decreased threshold. Methods Adult Mongolian gerbils (n = 36) received surgical fenestration of the superior semicircular canal of the left inner ear. ABR and c+VEMP testing were carried out prior to surgery and over acute (small 1 mm SSCD, 1-10 days) or prolonged (large 2 mm SSCD, 28 days) recovery. Because recovery of function occurred quickly, condenser brightfield stereomicroscopic examination of the dehiscence site was carried out for the small SSCD animals post-hoc and compared to both ABRs and c+VEMPs. Micro-CT analysis was also completed with representative samples of control, day 3 and 10 post-SSCD animals. Results The SSCD created a significant worsening of hearing thresholds of the left ear; especially in the lower frequency domain (1-4 kHz). Left (EXP)/right (CTL) ear comparisons via ABR show significant worsening thresholds at the same frequency representations, which is a proxy for the human pseudoconductive hearing loss seen in SSCD. For the c+VEMP measurements, increased amplitude of the sound-induced response (N1 2.5 ms and P1 3.2 ms) was observed in animals that received larger fenestrations. As the bone regrew, the c+VEMP and ABR responses returned toward preoperative values. For small SSCD animals, micro-CT data show that progressive osteoneogenesis results in resurfacing of the SSCD without bony obliteration. Conclusion The large (2 mm) SSCD used in our gerbil model results in similar electrophysiologic findings observed in patients with SSCD. The changes observed also reverse and return to baseline as the SSCD heals by bone resurfacing (with the lumen intact). Hence, this model does not require a second surgical procedure to plug the SSCD.
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Affiliation(s)
- P. Ashley Wackym
- Department of Otolaryngology – Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States,Rutgers Brain Health Institute, New Brunswick, NJ, United States
| | - Carey D. Balaban
- Departments of Otolaryngology, Neurobiology, Communication Sciences and Disorders, Bioengineering and Mechanical Engineering and Materials Science, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Olivia J. Van Osch
- Department of Otolaryngology – Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States
| | - Brian T. Morris
- Department of Otolaryngology – Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States
| | - Mark-Avery Tamakloe
- Department of Otolaryngology – Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States
| | - Victoria L. Salvatore
- Department of Otolaryngology – Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States
| | - Sudan Duwadi
- Department of Otolaryngology – Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States
| | - Jennifer D. Gay
- Department of Otolaryngology – Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States
| | - Todd M. Mowery
- Department of Otolaryngology – Head and Neck Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States,Rutgers Brain Health Institute, New Brunswick, NJ, United States,*Correspondence: Todd M. Mowery ✉
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30
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Chen A, Chen D, Lv K, Li G, Pan J, Ma D, Tang J, Zhang H. Zwitterionic Polymer/Polydopamine Coating of Electrode Arrays Reduces Fibrosis and Residual Hearing Loss after Cochlear Implantation. Adv Healthc Mater 2023; 12:e2200807. [PMID: 36177664 DOI: 10.1002/adhm.202200807] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 09/15/2022] [Indexed: 02/03/2023]
Abstract
Since the first surgery 50 years ago, cochlear implantation (CI) is the major treatment for patients with severe sensorineural hearing loss. However, unexpected foreign body reactions (FBRs) after surgery are reported in 90% of CI recipients, resulting in the formation of fibrosis in the cochlea and progressive residual hearing loss. Zwitterion modification is universally used to reduce bio-fouling and suppress FBRs but never for CI. In the present study, a zwitterionic coating is developed, which is composed of poly sulfobetaine methacrylate (PSB) and polydopamine (PDA) for cochlear implants. The PSB-PDA coating shows a series of characters for an ideal anti-FBRs material, including super-hydrophilicity, low protein and cell adsorption, long-term stability, and high biocompatibility. Compared to the uncoated controls, PSB-PDA coating inhibits the activation of macrophages and reduces the release of inflammatory factors (TNF-α, IL-1β, NO) and fibrosis-related factors (TGF-β1, α-SMA, collagen I). PSB-PDA coated electrode arrays suppress fibrosis completely and preserve residual hearing significantly in rat CI models. These results suggest that PSB-PDA coating is a novel strategy for anti-fibrosis to improve the outcomes of CI.
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Affiliation(s)
- Anning Chen
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China.,Hearing Research Center, Southern Medical University, Guangzhou, 510282, China
| | - Dongxiu Chen
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China.,Hearing Research Center, Southern Medical University, Guangzhou, 510282, China
| | - Kai Lv
- Guangdong Provincial Engineering and Technological Research Center for Drug Carrier Development, Key Laboratory of Biomaterials of Guangdong Higher Education Institutes, Department of Biomedical Engineering, Jinan University, Guangzhou, 510632, China
| | - Guowei Li
- Department of Nuclear Medicine and PET/CT-MRI Center, the First Affiliated Hospital of Jinan University, Guangzhou, 510630, China
| | - Jing Pan
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China.,Hearing Research Center, Southern Medical University, Guangzhou, 510282, China
| | - Dong Ma
- Guangdong Provincial Engineering and Technological Research Center for Drug Carrier Development, Key Laboratory of Biomaterials of Guangdong Higher Education Institutes, Department of Biomedical Engineering, Jinan University, Guangzhou, 510632, China
| | - Jie Tang
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China.,Hearing Research Center, Southern Medical University, Guangzhou, 510282, China.,Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China.,Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, 510515, China
| | - Hongzheng Zhang
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China.,Hearing Research Center, Southern Medical University, Guangzhou, 510282, China
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31
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Warnecke A, Staecker H, Rohde E, Gimona M, Giesemann A, Szczepek AJ, Di Stadio A, Hochmair I, Lenarz T. Extracellular Vesicles in Inner Ear Therapies-Pathophysiological, Manufacturing, and Clinical Considerations. J Clin Med 2022; 11:jcm11247455. [PMID: 36556073 PMCID: PMC9788356 DOI: 10.3390/jcm11247455] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/09/2022] [Accepted: 12/11/2022] [Indexed: 12/23/2022] Open
Abstract
(1) Background: Sensorineural hearing loss is a common and debilitating condition. To date, comprehensive pharmacologic interventions are not available. The complex and diverse molecular pathology that underlies hearing loss may limit our ability to intervene with small molecules. The current review foccusses on the potential for the use of extracellular vesicles in neurotology. (2) Methods: Narrative literature review. (3) Results: Extracellular vesicles provide an opportunity to modulate a wide range of pathologic and physiologic pathways and can be manufactured under GMP conditions allowing for their application in the human inner ear. The role of inflammation in hearing loss with a focus on cochlear implantation is shown. How extracellular vesicles may provide a therapeutic option for complex inflammatory disorders of the inner ear is discussed. Additionally, manufacturing and regulatory issues that need to be addressed to develop EVs as advanced therapy medicinal product for use in the inner ear are outlined. (4) Conclusion: Given the complexities of inner ear injury, novel therapeutics such as extracellular vesicles could provide a means to modulate inflammation, stress pathways and apoptosis in the inner ear.
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Affiliation(s)
- Athanasia Warnecke
- Department of Otolaryngology, Hannover Medical School, 30625 Hannover, Germany
- Cluster of Excellence of the German Research Foundation (DFG; “Deutsche Forschungsgemeinschaft”) “Hearing4all”, 30625 Hannover, Germany
- Correspondence:
| | - Hinrich Staecker
- Department of Otolaryngology Head and Neck Surgery, University of Kansas School of Medicine, Rainbow Blvd., Kansas City, KS 66160, USA
| | - Eva Rohde
- GMP Unit, Spinal Cord Injury & Tissue Regeneration Centre Salzburg (SCI-TReCS), Paracelsus Medical University, 5020 Salzburg, Austria
- Transfer Centre for Extracellular Vesicle Theralytic Technologies (EV-TT), 5020 Salzburg, Austria
- Department of Transfusion Medicine, University Hospital, Salzburger Landeskliniken GesmbH (SALK) Paracelsus Medical University, 5020 Salzburg, Austria
| | - Mario Gimona
- GMP Unit, Spinal Cord Injury & Tissue Regeneration Centre Salzburg (SCI-TReCS), Paracelsus Medical University, 5020 Salzburg, Austria
- Transfer Centre for Extracellular Vesicle Theralytic Technologies (EV-TT), 5020 Salzburg, Austria
- Research Program “Nanovesicular Therapies”, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Anja Giesemann
- Department of Diagnostic and Interventional Neuroradiology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Agnieszka J. Szczepek
- Department of Otorhinolaryngology, Head and Neck Surgery, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany
- Faculty of Medicine and Health Sciences, University of Zielona Gora, 65-046 Zielona Gora, Poland
| | - Arianna Di Stadio
- Department GF Ingrassia, University of Catania, 95124 Catania, Italy
| | | | - Thomas Lenarz
- Department of Otolaryngology, Hannover Medical School, 30625 Hannover, Germany
- Cluster of Excellence of the German Research Foundation (DFG; “Deutsche Forschungsgemeinschaft”) “Hearing4all”, 30625 Hannover, Germany
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Fallon JB, Dueck W, Trang EP, Smyth D, Wise AK. Effects of chronic implantation and long-term stimulation of a cochlear implant in the partial hearing cat model. Hear Res 2022; 426:108470. [PMID: 35249777 DOI: 10.1016/j.heares.2022.108470] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 01/23/2022] [Accepted: 02/21/2022] [Indexed: 12/16/2022]
Abstract
The expansion of criteria for cochlear implantation has resulted in increasing numbers of cochlear implant subjects having some level of residual hearing. The present study examined the effects of implantation surgery and long-term electrical stimulation on residual hearing in a partially deafened cat model. Eighteen animals were partially deafened, implanted and chronically stimulated. Implantation resulted in a pronounced loss evident 2-weeks post implantation of up to 30-40 dB at 4 & 8 kHz which was statistically significant (2-way RM ANOVA (Time, Frequency): p(Time) = 0.001; p(Frequency) < 0.001; p(Time x Frequency) < 0.001)). Chronic stimulation resulted in a significant (RM ANOVA: p(Time) = 0.030) ongoing hearing loss, with 5 animals (∼30%) exhibiting an increase in threshold of 20 dB or more. Different loss profiles were evident with peripheral and central hearing assessments suggests that changes in 'central gain' may be occurring. Despite significant loss of hair cells and spiral ganglion neurons and distinct fibrous tissue growth in the scala tympani following implantation and long-term electrical stimulation, there were no significant correlations with any histological measures and ongoing hearing loss. The partially deafened, chronically stimulated cat model provides a clinically relevant model in which to further investigate the cause of the delayed hearing loss following cochlear implant surgery and use.
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Affiliation(s)
- James B Fallon
- Bionics Institute, Victoria, Australia; Medical Bionics Department, University of Melbourne, Victoria, Australia.
| | | | | | | | - Andrew K Wise
- Bionics Institute, Victoria, Australia; Medical Bionics Department, University of Melbourne, Victoria, Australia
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33
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Gantz BJ, Hansen M, Dunn CC. Clinical perspective on hearing preservation in cochlear implantation, the University of Iowa experience. Hear Res 2022; 426:108487. [PMID: 35410721 PMCID: PMC9482999 DOI: 10.1016/j.heares.2022.108487] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 02/17/2022] [Accepted: 03/15/2022] [Indexed: 12/16/2022]
Abstract
Preservation of residual acoustic hearing has emerged as an important concept for those individuals undergoing cochlear implantation with residual low frequency hearing. Acoustic plus electric speech processing improves hearing outcomes in quiet, enables melody recognition, preserves spatial hearing if there is acoustic hearing in both ears and significantly improves hearing in noise. The development of our experience with acoustic plus electric processing is reviewed along with clinical trials and patient outcomes that our team has documented over the past twenty years.
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Affiliation(s)
- Bruce J Gantz
- The University of Iowa Cochlear Implant Clinical Research Center, Department of Otolaryngology-Head and Neck Surgery, University of Iowa Carver College of Medicine, Iowa City, IA United States.
| | - Marlan Hansen
- The University of Iowa Cochlear Implant Clinical Research Center, Department of Otolaryngology-Head and Neck Surgery, University of Iowa Carver College of Medicine, Iowa City, IA United States
| | - Camille C Dunn
- The University of Iowa Cochlear Implant Clinical Research Center, Department of Otolaryngology-Head and Neck Surgery, University of Iowa Carver College of Medicine, Iowa City, IA United States
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34
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Effects of an enhanced acoustic environment on residual hearing following chronic cochlear implantation and electrical stimulation in the partially deafened cat. Hear Res 2022; 426:108635. [DOI: 10.1016/j.heares.2022.108635] [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: 11/03/2021] [Revised: 08/10/2022] [Accepted: 10/11/2022] [Indexed: 11/04/2022]
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35
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Muacevic A, Adler JR, Alsalhi HS, Hagr A. Cochlear Implant Induced Labyrinthine Ossificans in Mondini Malformation: A Case Series. Cureus 2022; 14:e32648. [PMID: 36654620 PMCID: PMC9842388 DOI: 10.7759/cureus.32648] [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] [Accepted: 11/24/2022] [Indexed: 12/23/2022] Open
Abstract
Cochlear implantation is relatively a safe procedure with a favorable outcome. Labyrinthine ossification is one of the rare complications that has been observed in some occasions post-cochlear implantation. This paper report two cases of Mondini inner ear malformation cochlear implant failure associated with labyrinthine ossification, mandating revision surgery, and a literature review focusing on the reported cases, risk factors, surgical and non-surgical measures to mitigate this complication and to improve overall cochlear implant outcomes.
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36
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Claussen AD, Shibata SB, Kaufmann CR, Henslee A, Hansen MR. Comparative Analysis of Robotics-Assisted and Manual Insertions of Cochlear Implant Electrode Arrays. Otol Neurotol 2022; 43:1155-1161. [PMID: 36201552 PMCID: PMC10962863 DOI: 10.1097/mao.0000000000003707] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
HYPOTHESIS Robotics-assisted cochlear implant (CI) insertions will result in reduced intracochlear trauma when compared with manual, across multiple users. BACKGROUND Whether intracochlear trauma and translocations are two factors that may contribute to significant variability in CI outcomes remains to be seen. To address this issue, we have developed a robotics-assisted insertion system designed to aid the surgeon in inserting electrode arrays with consistent speeds and reduced variability. This study evaluated the effect of robotics-assisted insertions on the intracochlear trauma as compared with manual insertions in cadaveric cochleae in a simulated operative environment. METHODS Twelve neurotologists performed bilateral electrode insertions into cochleae of full cadaveric heads using both the robotics-assisted system and manual hand insertion. Lateral wall electrodes from three different manufacturers (n = 24) were used and randomized between surgeons. Insertion angle of the electrode and trauma scoring were evaluated using high-resolution three-dimensional x-ray microscopy and compared between robotics-assisted and manual insertions. RESULTS Three-dimensional x-ray microscopy provided excellent resolution to characterize the in situ trauma and insertion angle. Robotics-assisted insertions significantly decreased insertional intracochlear trauma as measured by reduced trauma scores compared with manual insertions (average: 1.3 versus 2.2, device versus manual, respectively; p < 0.05). There was no significant difference between insertion angles observed for manual and robotics-assisted techniques (311 ± 131° versus 307 ± 96°, device versus manual, respectively). CONCLUSIONS Robotics-assisted insertion systems enable standardized electrode insertions across individual surgeons and experience levels. Clinical trials are necessary to investigate whether insertion techniques that reduce insertional variability and the likelihood of intracochlear trauma also improve CI auditory outcomes.
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Affiliation(s)
| | - Seiji B Shibata
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa
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37
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Jensen MJ, Claussen AD, Higgins T, Vielman-Quevedo R, Mostaert B, Xu L, Kirk J, Hansen MR. Cochlear implant material effects on inflammatory cell function and foreign body response. Hear Res 2022; 426:108597. [PMID: 35963812 PMCID: PMC10875706 DOI: 10.1016/j.heares.2022.108597] [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: 08/22/2021] [Revised: 07/08/2022] [Accepted: 08/03/2022] [Indexed: 11/28/2022]
Abstract
OBJECTIVES The objectives of this study were to assess the effects of cochlear implant (CI) biomaterials on the function of macrophages and fibroblasts, two key mediators of the foreign body response (FBR) and to determine how these materials influence fibrous tissue growth and new bone formation within the cochlea. METHODS Macrophages and fibroblasts were cultured on polydimethylsiloxane (PDMS) and platinum substrates and human CI electrodes in vitro. Cell count, cell proliferation, cytokine production, and cell adhesion were measured. CI electrodes were implanted into murine cochleae for three weeks without electrical stimulation. Implanted cochleae were harvested for 3D X-ray microscopy with the CI left in-situ. The location of new bone growth within the scala tympani (ST) with reference to different portions of the implant (PDMS vs platinum) was quantified. RESULTS Cell counts of macrophages and fibroblasts were significantly higher on platinum substrates and platinum contacts of CI electrodes. Fibroblast proliferation was greater on platinum relative to PDMS, and cells grown on platinum formed more/larger focal adhesions. 3D X-ray microscopy showed neo-ossification in the peri‑implant areas of the ST. Volumetric quantification of neo-ossification showed a trend toward greater bone formation adjacent to the platinum electrodes compared to areas opposite or away from the platinum electrode bearing surfaces. CONCLUSIONS Fibrotic reactions are biomaterial specific, as demonstrated by the differences in cell adhesion, proliferation, and fibrosis on platinum and PDMS. The inflammatory reaction to platinum contacts on CI electrodes likely contributes to fibrosis to a greater degree than PDMS, and platinum contacts may influence the deposition of new bone, as demonstrated in the in vivo data. This information can potentially be used to influence the design of future generations of neural prostheses.
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Affiliation(s)
- Megan J Jensen
- Department of Otolaryngology-Head & Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, United States
| | - Alexander D Claussen
- Department of Otolaryngology-Head & Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, United States
| | - Timon Higgins
- Carver College of Medicine, Iowa City, IA, United States
| | - Rene Vielman-Quevedo
- Department of Otolaryngology-Head & Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, United States
| | - Brian Mostaert
- Department of Otolaryngology-Head & Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, United States
| | - Linjing Xu
- Department of Otolaryngology-Head & Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, United States
| | | | - Marlan R Hansen
- Department of Otolaryngology-Head & Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, United States; Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, IA, United States.
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38
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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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Claussen AD, Quevedo RV, Kirk JR, Higgins T, Mostaert B, Rahman MT, Oleson J, Hernandez R, Hirose K, Hansen MR. Chronic cochlear implantation with and without electric stimulation in a mouse model induces robust cochlear influx of CX3CR1 +/GFP macrophages. Hear Res 2022; 426:108510. [PMID: 35527124 PMCID: PMC9596618 DOI: 10.1016/j.heares.2022.108510] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 03/27/2022] [Accepted: 04/23/2022] [Indexed: 12/16/2022]
Abstract
BACKGROUND Cochlear implantation is an effective auditory rehabilitation strategy for those with profound hearing loss, including those with residual low frequency hearing through use of hybrid cochlear implantation techniques. Post-mortem studies demonstrate the nearly ubiquitous presence of intracochlear fibrosis and neo-ossification following cochlear implantation. Current evidence suggests post-implantation intracochlear fibrosis is associated with delayed loss of residual acoustic hearing in hybrid cochlear implant (CI) recipients and may also negatively influence outcomes in traditional CI recipients. This study examined the contributions of surgical trauma, foreign body response and electric stimulation to intracochlear fibrosis and the innate immune response to cochlear implantation and the hierarchy of these contributions. METHODS Normal hearing CX3CR1+/GFP mice underwent either round window opening (sham), acute CI insertion or chronic CI insertion with no, low- or high-level electric stimulation. Electric stimulation levels were based on neural response telemetry (NRT), beginning post-operative day 7 for 5 h per day. Subjects (n=3 per timepoint) were sacrificed at 4 h, 1,4,7,8,11,14 and 21 days. An unoperated group (n=3) served as controls. Cochleae were harvested at each time-point and prepared for immunohistochemistry with confocal imaging. The images were analyzed to obtain CX3CR1+ macrophage cell number and density in the lateral wall (LW), scala tympani (ST) and Rosenthal's canal (RC). RESULTS A ST peri-implant cellular infiltrate and fibrosis occurred exclusively in the chronically implanted groups starting on day 7 with a concurrent infiltration of CX3CR1+ macrophages not seen in the other groups. CX3CR1+ macrophage infiltration was seen in the LW and RC in all experimental groups within the first week, being most prominent in the 3 chronically implanted groups during the second and third week. CONCLUSIONS The cochlear immune response was most prominent in the presence of chronic cochlear implantation, regardless of electric stimulation level. Further, the development of intracochlear ST fibrosis was dependent on the presence of the indwelling CI foreign body. An innate immune response was evoked by surgical trauma alone (sham and acute CI groups) to a lesser degree. These data suggest that cochlear inflammation and intrascalar fibrosis after cochlear implantation are largely dependent on the presence of a chronic indwelling foreign body and are not critically dependent on electrical stimulation. Also, these data support a role for surgical trauma in inciting the initial innate immune response.
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Affiliation(s)
- Alexander D Claussen
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, United States; Department of Otolaryngology Head and Neck Surgery, University of California San Diego, San Diego, CA 92103, United States.
| | - René Vielman Quevedo
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, United States; Department of Biomedical Sciences, Creighton University, Omaha, NE 68178, United States
| | | | - Timon Higgins
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, United States
| | - Brian Mostaert
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, United States
| | - Muhammad Taifur Rahman
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, United States
| | - Jacob Oleson
- Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, IA 52242, United States
| | - Reyna Hernandez
- Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, IA 52242, United States
| | - Keiko Hirose
- Department of Otolaryngology Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO 63110, United States
| | - Marlan R Hansen
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, United States
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Santi PA, Johnson S, Wüster J, Griesbach M, Claussen A, Kirk J. Cochlear Implant Imaging in the Mouse and Guinea Pig Using Light-Sheet Microscopy. Hear Res 2022; 426:108639. [DOI: 10.1016/j.heares.2022.108639] [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: 01/31/2022] [Revised: 09/17/2022] [Accepted: 10/18/2022] [Indexed: 11/04/2022]
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Chen A, Chen Y, Liu S, Ma D, Tang J, Zhang H. Mesoporous silica nanoparticle-modified electrode arrays of cochlear implants for delivery of siRNA-TGFβ1 into the inner ear. Colloids Surf B Biointerfaces 2022; 218:112753. [PMID: 35963142 DOI: 10.1016/j.colsurfb.2022.112753] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 06/29/2022] [Accepted: 08/03/2022] [Indexed: 10/16/2022]
Abstract
Cochlear implants (CI) are widely used in patients to restore hearing function. Uncontrolled fibrosis in the cochleae induced by excess secretion of TGFβ1 seriously affects the effectiveness of CIs. siRNA is a potential therapeutic strategy to downregulate TGFβ1 specifically. However, treatment with siRNA in cochleae is difficult due to the poor penetration capability and instability of siRNA and the inaccessibility and vulnerability of cochleae. To address these challenges, we developed amino-functionalized mesoporous silica nanoparticle (MSN-NH2)-modified electrode arrays to deliver siRNA-TGFβ1 into the inner ear. The shape, diameter, pore diameter, and zeta potential of MSN-NH2 were investigated. siRNA loading capability and protective effect of MSN-NH2 were determined by agarose gel electrophoresis assay. The cytotoxicity, cellular uptake assay, and TGFβ1 knockdown efficiency of MSN-NH2 were studied by CCK-8 assay, flow cytometry, and real-time PCR, respectively. MSN-NH2-siTGFβ1 nanoparticles were absorbed into the electrode arrays and worked in the cochleae. MSN-NH2-siTGFβ1-modified CI electrode arrays may be an attractive therapeutic clinical intervention strategy to inhibit cochlear implantation fibrosis.
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Affiliation(s)
- Anning Chen
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China; Hearing Research Center, Southern Medical University, Guangzhou 510282, China
| | - Yaoheng Chen
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China; Hearing Research Center, Southern Medical University, Guangzhou 510282, China
| | - Shixin Liu
- Guangdong Provincial Engineering and Technological Research Center for Drug Carrier Development, Key Laboratory of Biomaterials of Guangdong Higher Education Institutes, Department of Biomedical Engineering, Jinan University, Guangzhou 510632, China
| | - Dong Ma
- Guangdong Provincial Engineering and Technological Research Center for Drug Carrier Development, Key Laboratory of Biomaterials of Guangdong Higher Education Institutes, Department of Biomedical Engineering, Jinan University, Guangzhou 510632, China.
| | - Jie Tang
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China; Hearing Research Center, Southern Medical University, Guangzhou 510282, China; Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China; Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou 510515, China.
| | - Hongzheng Zhang
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China; Hearing Research Center, Southern Medical University, Guangzhou 510282, China.
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Jensen MJ, Isaac H, Hernandez H, Oleson J, Dunn C, Gantz BJ, Hansen MR. Timing of Acoustic Hearing Changes After Cochlear Implantation. Laryngoscope 2022; 132:2036-2043. [PMID: 34882792 PMCID: PMC9177890 DOI: 10.1002/lary.29984] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 11/01/2021] [Accepted: 12/02/2021] [Indexed: 11/10/2022]
Abstract
OBJECTIVES/HYPOTHESIS To determine the timing of acoustic hearing changes among hearing preservation Cochlear implant (CI) recipients. To determine differences in hearing outcomes based on device type and demographic factors. To determine if there is a relationship between the extent of early hearing loss after CI and the subsequent rate of continued hearing loss. STUDY DESIGN Prospective, single subject study. METHODS Two hundred and eleven subjects who received a hearing preservation CI were included in the study-80 Nucleus Hybrid L24 (Cochlear), 47 422/522 (Cochlear), 24 S8 (Cochlear), 14 S12 (Cochlear), 6 SRW (Cochlear), 21 SLIM J (Advanced Bionics), and 19 Flex (Med-EL). Of these, 127 were included in the subsequent analyses. Audiometric thresholds (low frequency pure-tone-averages) were collected and compared pre and postoperatively. RESULTS Long-term hearing preservation rates were 65% (52/80) for L24, 83% (20/24) for S8, 79% (11/14) for S12, 83% (5/6) for SRW, 54% (25/47) for 422/522, 91% (21/23) for SLIM J, and 84% (16/19) for Flex. Hearing loss was not related to device type (P = .9105) or gender (P = .2169). Older subjects (age ≥65) had worse hearing outcomes than younger subjects after initial device activation (age <65, P = .0262). There was no significant difference in rate of hearing loss over time between older and younger patients (P = .0938). Initial postoperative hearing loss was not associated with the rate of long-term hearing loss. CONCLUSIONS Long-term low frequency hearing preservation is possible for CI recipients and is not associated with gender or device type. Rate of hearing loss over time is not dependent on patient age. Early hearing loss after CI does not predict the rate of long-term hearing loss. LEVEL OF EVIDENCE 3 Laryngoscope, 132:2036-2043, 2022.
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Affiliation(s)
- Megan J. Jensen
- Department of Otolaryngology – Head & Neck Surgery, University of Iowa, Iowa City, IA, USA
| | - Heba Isaac
- Department of Otolaryngology – Head & Neck Surgery, University of Iowa, Iowa City, IA, USA
| | - Helin Hernandez
- Department of Biostatistics, University of Iowa, Iowa City, IA, USA
| | - Jacob Oleson
- Department of Biostatistics, University of Iowa, Iowa City, IA, USA
| | - Camille Dunn
- Department of Otolaryngology – Head & Neck Surgery, University of Iowa, Iowa City, IA, USA
| | - Bruce J. Gantz
- Department of Otolaryngology – Head & Neck Surgery, University of Iowa, Iowa City, IA, USA
- Departments of Neurosurgery, University of Iowa, Iowa City, IA, USA
| | - Marlan R. Hansen
- Department of Otolaryngology – Head & Neck Surgery, University of Iowa, Iowa City, IA, USA
- Departments of Neurosurgery, University of Iowa, Iowa City, IA, USA
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Reiss LA, Kirk J, Claussen AD, Fallon JB. Animal Models of Hearing Loss after Cochlear Implantation and Electrical Stimulation. Hear Res 2022; 426:108624. [DOI: 10.1016/j.heares.2022.108624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 03/28/2022] [Accepted: 09/23/2022] [Indexed: 11/04/2022]
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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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Four-point Impedance Changes in the Early Post-Operative Period After Cochlear Implantation. Otol Neurotol 2022; 43:e730-e737. [PMID: 35861642 DOI: 10.1097/mao.0000000000003592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Monitoring four-point impedance changes after cochlear implantation with comparison to conventional impedance measurements. Four-point impedance provides information regarding the bulk biological environment surrounding the electrode array, which is not discernible with conventional impedances. STUDY DESIGN Prospective observational. SETTING Hospital. PATIENTS Adult cochlear implant recipients with no measurable hearing before implantation and implanted with a perimodiolar cochlear implant. MAIN OUTCOME MEASURES Mean values for four-point and common ground impedances were calculated for all electrode contacts at intra-operative, 1 day, 1 week, 4 to 6 weeks, and 3 months post implantation. Linear mixed models were applied to the impedance data to compare between impedances and time points. Furthermore, patients were divided into groups dependent on the normalized change in four-point impedance from intra-operative to 1 day post-operative. The normalized change was then calculated for all other time points and compared across the two groups. RESULTS Significant increases in four-point impedance occurred 1 day and 3 months after surgery, particularly in the basal half of the array. Four-point impedance at 1 day was highly predictive of four-point impedance at 3 months. Four-point impedance at the other time points showed marginal or no increases from intra-operative. Patients with an average increase higher than 10% in four-point impedance from intra-operative to 1 day, had significantly higher values at 3 months ( p = 0.012). These patterns were not observed in common ground impedance. CONCLUSION This is the first study to report increases in four-point impedance within 24 hours of cochlear implantation. The increases at 1 day and 3 months align with the natural timeline of an acute and chronic inflammatory responses.
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Van de Heyning P, Roland P, Lassaletta L, Agrawal S, Atlas M, Baumgartner WD, Brown K, Caversaccio M, Dazert S, Gstoettner W, Hagen R, Hagr A, Jablonski GE, Kameswaran M, Kuzovkov V, Leinung M, Li Y, Loth A, Magele A, Mlynski R, Mueller J, Parnes L, Radeloff A, Raine C, Rajan G, Schmutzhard J, Skarzynski H, Skarzynski PH, Sprinzl G, Staecker H, Stöver T, Tavora-Viera D, Topsakal V, Usami SI, Van Rompaey V, Weiss NM, Wimmer W, Zernotti M, Gavilan J. Suitable Electrode Choice for Robotic-Assisted Cochlear Implant Surgery: A Systematic Literature Review of Manual Electrode Insertion Adverse Events. Front Surg 2022; 9:823219. [PMID: 35402479 PMCID: PMC8987358 DOI: 10.3389/fsurg.2022.823219] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 02/09/2022] [Indexed: 12/05/2022] Open
Abstract
Background and Objective The cochlear implant (CI) electrode insertion process is a key step in CI surgery. One of the aims of advances in robotic-assisted CI surgery (RACIS) is to realize better cochlear structure preservation and to precisely control insertion. The aim of this literature review is to gain insight into electrode selection for RACIS by acquiring a thorough knowledge of electrode insertion and related complications from classic CI surgery involving a manual electrode insertion process. Methods A systematic electronic search of the literature was carried out using PubMed, Scopus, Cochrane, and Web of Science to find relevant literature on electrode tip fold over (ETFO), electrode scalar deviation (ESD), and electrode migration (EM) from both pre-shaped and straight electrode types. Results A total of 82 studies that include 8,603 ears implanted with a CI, i.e., pre-shaped (4,869) and straight electrodes (3,734), were evaluated. The rate of ETFO (25 studies, 2,335 ears), ESD (39 studies, 3,073 ears), and EM (18 studies, 3,195 ears) was determined. An incidence rate (±95% CI) of 5.38% (4.4–6.6%) of ETFO, 28.6% (26.6–30.6%) of ESD, and 0.53% (0.2–1.1%) of EM is associated with pre-shaped electrodes, whereas with straight electrodes it was 0.51% (0.1–1.3%), 11% (9.2–13.0%), and 3.2% (2.5–3.95%), respectively. The differences between the pre-shaped and straight electrode types are highly significant (p < 0.001). Laboratory experiments show evidence that robotic insertions of electrodes are less traumatic than manual insertions. The influence of round window (RW) vs. cochleostomy (Coch) was not assessed. Conclusion Considering the current electrode designs available and the reported incidence of insertion complications, the use of straight electrodes in RACIS and conventional CI surgery (and manual insertion) appears to be less traumatic to intracochlear structures compared with pre-shaped electrodes. However, EM of straight electrodes should be anticipated. RACIS has the potential to reduce these complications.
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Affiliation(s)
- Paul Van de Heyning
- Department of Otorhinolaryngology Head and Neck Surgery, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium
- Department of Translational Neurosciences, University of Antwerp, Antwerp, Belgium
- *Correspondence: Paul Van de Heyning
| | - Peter Roland
- Department of Otolaryngology, Head & Neck Surgery, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Luis Lassaletta
- Hospital Universitario La Paz, Institute for Health Research (IdiPAZ), Madrid, Spain
| | - Sumit Agrawal
- Department of Otolaryngology-Head and Neck Surgery, Western University, London, ON, Canada
| | - Marcus Atlas
- Ear Sciences Institute Australia, Lions Hearing Clinic, Perth, WA, Australia
| | | | - Kevin Brown
- UNC Ear and Hearing Center at Chapel Hill School of Medicine, Chapel Hill, NC, United States
| | - Marco Caversaccio
- Department for ENT, Head and Neck Surgery, Bern University Hospital, Bern, Switzerland
| | - Stefan Dazert
- Department of Otorhinolaryngology-Head and Neck Surgery, Ruhr-University Bochum, St. Elisabeth University Hospital Bochum, Bochum, Germany
| | | | - Rudolf Hagen
- Würzburg ENT University Hospital, Würzburg, Germany
| | - Abdulrahman Hagr
- King Abdullah Ear Specialist Center, King Saud University Medical City, King Saud University, Riyadh, Saudi Arabia
| | - Greg Eigner Jablonski
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
- Department of Otorhinolaryngology & Head and Neck Surgery, Oslo University Hospital, Rikshospitalet, Oslo, Norway
| | | | - Vladislav Kuzovkov
- St. Petersburg ENT and Speech Research Institute, St. Petersburg, Russia
| | - Martin Leinung
- Department of Otolaryngology, Head and Neck Surgery, University Hospital Frankfurt, Frankfurt am Main, Germany
| | - Yongxin Li
- Department of Otorhinolaryngology Head and Neck Surgery, Beijing Tongren Hospital, Capital Medical University, Beijing, China
- Key Laboratory of Otolaryngology Head and Neck Surgery (Capital Medical University), Ministry of Education, Beijing, China
| | - Andreas Loth
- Department of Otolaryngology, Head and Neck Surgery, University Hospital Frankfurt, Frankfurt am Main, Germany
| | - Astrid Magele
- Ear, Nose and Throat Department, University Clinic St. Poelten, Karl Landsteiner Private University, St. Poelten, Austria
| | - Robert Mlynski
- Department of Otorhinolaryngology, Head and Neck Surgery, “Otto Körner” Rostock University Medical Center, Rostock, Germany
| | - Joachim Mueller
- Klinik und Poliklinik für Hals-, Nasen- und Ohrenheilkunde, Ludwig-Maximilians-Universitat Munchen, Munchen, Germany
| | - Lorne Parnes
- Department of Otolaryngology-Head and Neck Surgery, Western University, London, ON, Canada
| | - Andreas Radeloff
- Division of Oto-Rhino-Laryngology, Evangelisches Krankenhaus Oldenburg, Research Center of Neurosensory Sciences, University Oldenburg, Oldenburg, Germany
| | - Chris Raine
- Bradford Royal Infirmary Yorkshire Auditory Implant Center, Bradford, United Kingdom
| | - Gunesh Rajan
- Department of Otolaryngology, Head and Neck Surgery, Luzerner Kantonsspital, Luzern, Medical Sciences Department of Health Sciences and Medicine. University of Lucerne, Luzern, Switzerland. Otolaryngology, Head & Neck Surgery, Medical School University of Western Australia, Perth, WA, Australia
| | - Joachim Schmutzhard
- Department of Otorhinolaryngology, Medical University of Innsbruck, Innsbruck, Austria
| | - Henryk Skarzynski
- Department of Teleaudiology and Screening, World Hearing Center of the Institute of Physiology and Pathology of Hearing, Kajetany, Poland
| | - Piotr H. Skarzynski
- Department of Teleaudiology and Screening, World Hearing Center of the Institute of Physiology and Pathology of Hearing, Kajetany, Poland
| | - Georg Sprinzl
- Ear, Nose and Throat Department, University Clinic St. Poelten, Karl Landsteiner Private University, St. Poelten, Austria
| | - Hinrich Staecker
- Kansas University Center for Hearing and Balance Disorders, Kansas City, KS, United States
| | - Timo Stöver
- Department of Otolaryngology, Head and Neck Surgery, University Hospital Frankfurt, Frankfurt am Main, Germany
| | | | - Vedat Topsakal
- Department of ENT HNS, University Hospital Brussels, Brussels, Belgium
| | - Shin-Ichi Usami
- Department of Hearing Implant Sciences, Shinshu University School of Medicine, Nagano, Japan
| | - Vincent Van Rompaey
- Department of Otorhinolaryngology Head and Neck Surgery, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium
- Department of Translational Neurosciences, University of Antwerp, Antwerp, Belgium
| | - Nora M. Weiss
- Department of Otorhinolaryngology-Head and Neck Surgery, Ruhr-University Bochum, St. Elisabeth University Hospital Bochum, Bochum, Germany
| | - Wilhelm Wimmer
- Department for ENT, Head and Neck Surgery, Bern University Hospital, Bern, Switzerland
| | - Mario Zernotti
- Catholic University of Córdoba and National University of Córdoba, Córdoba, Argentina
| | - Javier Gavilan
- Hospital Universitario La Paz, Institute for Health Research (IdiPAZ), Madrid, Spain
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Walia A, Shew MA, Kallogjeri D, Wick CC, Durakovic N, Lefler SM, Ortmann AJ, Herzog JA, Buchman CA. Electrocochleography and cognition are important predictors of speech perception outcomes in noise for cochlear implant recipients. Sci Rep 2022; 12:3083. [PMID: 35197556 PMCID: PMC8866505 DOI: 10.1038/s41598-022-07175-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 02/10/2022] [Indexed: 11/15/2022] Open
Abstract
Although significant progress has been made in understanding outcomes following cochlear implantation, predicting performance remains a challenge. Duration of hearing loss, age at implantation, and electrode positioning within the cochlea together explain ~ 25% of the variability in speech-perception scores in quiet using the cochlear implant (CI). Electrocochleography (ECochG) responses, prior to implantation, account for 47% of the variance in the same speech-perception measures. No study to date has explored CI performance in noise, a more realistic measure of natural listening. This study aimed to (1) validate ECochG total response (ECochG-TR) as a predictor of performance in quiet and (2) evaluate whether ECochG-TR explained variability in noise performance. Thirty-five adult CI recipients were enrolled with outcomes assessed at 3-months post-implantation. The results confirm previous studies showing a strong correlation of ECochG-TR with speech-perception in quiet (r = 0.77). ECochG-TR independently explained 34% of the variability in noise performance. Multivariate modeling using ECochG-TR and Montreal Cognitive Assessment (MoCA) scores explained 60% of the variability in speech-perception in noise. Thus, ECochG-TR, a measure of the cochlear substrate prior to implantation, is necessary but not sufficient for explaining performance in noise. Rather, a cognitive measure is also needed to improve prediction of noise performance.
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Affiliation(s)
- Amit Walia
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine in St. Louis, 660 S. Euclid Ave, Campus Box 8115, St. Louis, MO, 63110, USA.
| | - Matthew A Shew
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine in St. Louis, 660 S. Euclid Ave, Campus Box 8115, St. Louis, MO, 63110, USA
| | - Dorina Kallogjeri
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine in St. Louis, 660 S. Euclid Ave, Campus Box 8115, St. Louis, MO, 63110, USA
| | - Cameron C Wick
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine in St. Louis, 660 S. Euclid Ave, Campus Box 8115, St. Louis, MO, 63110, USA
| | - Nedim Durakovic
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine in St. Louis, 660 S. Euclid Ave, Campus Box 8115, St. Louis, MO, 63110, USA
| | - Shannon M Lefler
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine in St. Louis, 660 S. Euclid Ave, Campus Box 8115, St. Louis, MO, 63110, USA
| | - Amanda J Ortmann
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine in St. Louis, 660 S. Euclid Ave, Campus Box 8115, St. Louis, MO, 63110, USA
| | - Jacques A Herzog
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine in St. Louis, 660 S. Euclid Ave, Campus Box 8115, St. Louis, MO, 63110, USA
| | - Craig A Buchman
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine in St. Louis, 660 S. Euclid Ave, Campus Box 8115, St. Louis, MO, 63110, USA
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Intracochlear New Fibro-Ossification and Neuronal Degeneration Following Cochlear Implant Electrode Translocation: Long-Term Histopathological Findings in Humans. Otol Neurotol 2022; 43:e153-e164. [PMID: 35015749 DOI: 10.1097/mao.0000000000003402] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
OBJECTIVE We aim to assess the histopathology of human temporal bones (TBs) with evidence of cochlear implantation (CI) electrode scalar translocation. STUDY DESIGN Otopathology study. SETTING Otopathology laboratory. PATIENTS TBs from patients who had a history of CI and histopathological evidence of interscalar translocation. Specimens with electrode placed entirely within the ST served as controls. INTERVENTION Histopathological assessment of human TBs. MAIN OUTCOME MEASURES TBs from each patient were harvested postmortem and histologically analyzed for intracochlear changes in the context of CI electrode translocation and compared to controls. Intracochlear new fibro-ossification, and spiral ganglion neuron (SGN) counts were assessed. Postoperative word recognition scores (WRS) were also compared. RESULTS Nineteen human TBs with electrode translocation and eight controls were identified. The most common site of translocation was the ascending limb of the basal turn (n = 14 TBs). The average angle of insertion at the point of translocation was 159° ± 79°. Eighteen translocated cases presented moderate fibroosseous changes in the basal region of the cochlea, extending to the translocation point and/or throughout the electrode track in 42%. Lower SGN counts were more pronounced in translocated cases compared to controls, with a significant difference for segment II (p = 0.019). Although final postoperative hearing outcomes were similar between groups, translocated cases had slower rate of improvement in WRS (p = 0.021). CONCLUSIONS Cochlear implant electrode translocation was associated with greater fibroosseous formation and lower SGN population. Our findings suggest that scalar translocations may slow the rate of improvement in WRS overtime as compared to atraumatic electrode insertions.Level of evidence: IV.
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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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Walia A, Shew MA, Lefler SM, Kallogjeri D, Wick CC, Holden TA, Durakovic N, Ortmann AJ, Herzog JA, Buchman CA. Is Characteristic Frequency Limiting Real-Time Electrocochleography During Cochlear Implantation? Front Neurosci 2022; 16:915302. [PMID: 35937872 PMCID: PMC9354607 DOI: 10.3389/fnins.2022.915302] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 06/15/2022] [Indexed: 12/05/2022] Open
Abstract
Objectives Electrocochleography (ECochG) recordings during cochlear implantation have shown promise in estimating the impact on residual hearing. The purpose of the study was (1) to determine whether a 250-Hz stimulus is superior to 500-Hz in detecting residual hearing decrement and if so; (2) to evaluate whether crossing the 500-Hz tonotopic, characteristic frequency (CF) place partly explains the problems experienced using 500-Hz. Design Multifrequency ECochG comprising an alternating, interleaved acoustic complex of 250- and 500-Hz stimuli was used to elicit cochlear microphonics (CMs) during insertion. The largest ECochG drops (≥30% reduction in CM) were identified. After insertion, ECochG responses were measured using the individual electrodes along the array for both 250- and 500-Hz stimuli. Univariate regression was used to predict whether 250- or 500-Hz CM drops explained low-frequency pure tone average (LFPTA; 125-, 250-, and 500-Hz) shift at 1-month post-activation. Postoperative CT scans were performed to evaluate cochlear size and angular insertion depth. Results For perimodiolar insertions (N = 34), there was a stronger linear correlation between the largest ECochG drop using 250-Hz stimulus and LFPTA shift (r = 0.58), compared to 500-Hz (r = 0.31). The 250- and 500-Hz CM insertion tracings showed an amplitude peak at two different locations, with the 500-Hz peak occurring earlier in most cases than the 250-Hz peak, consistent with tonotopicity. When using the entire array for recordings after insertion, a maximum 500-Hz response was observed 2-6 electrodes basal to the most-apical electrode in 20 cases (58.9%). For insertions where the apical insertion angle is >350 degrees and the cochlear diameter is <9.5 mm, the maximum 500-Hz ECochG response may occur at the non-apical most electrode. For lateral wall insertions (N = 14), the maximum 250- and 500-Hz CM response occurred at the most-apical electrode in all but one case. Conclusion Using 250-Hz stimulus for ECochG feedback during implantation is more predictive of hearing preservation than 500-Hz. This is due to the electrode passing the 500-Hz CF during insertion which may be misidentified as intracochlear trauma; this is particularly important in subjects with smaller cochlear diameters and deeper insertions. Multifrequency ECochG can be used to differentiate between trauma and advancement of the apical electrode beyond the CF.
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