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Wei C, Gao Z, Mau R, Eickner T, Jüttner G, Fiedler N, Seitz H, Lenarz T, Scheper V. Molded Round Window Niche Implant as a Dexamethasone Delivery System in a Cochlear Implant-Trauma Animal Model. Pharmaceutics 2024; 16:1236. [PMID: 39339272 PMCID: PMC11434969 DOI: 10.3390/pharmaceutics16091236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2024] [Revised: 09/04/2024] [Accepted: 09/06/2024] [Indexed: 09/30/2024] Open
Abstract
BACKGROUND Preserving residual hearing after cochlear implant (CI) surgery remains a crucial challenge. The application of dexamethasone (DEX) has been proven to positively affect residual hearing. To deliver DEX in a localized and controlled way, a round window niche implant (RNI), allowing drug diffusion via the round window membrane into the cochlea, may be used. To prove this concept, an RNI for guinea pigs as a CI-trauma model was manufactured by molding and tested for its drug release in vitro and biological effects in vivo. METHODS The RNIs were molded using silicone containing 10% DEX. Release was analyzed over time using high-performance liquid chromatography (HPLC). Fourteen adult guinea pigs were randomly assigned to two groups (CI or CI + RNI group). All animals received a unilateral CI electrode insertion trauma followed by CI insertion. The CI + RNI group was additionally implanted with an RNI containing 10% DEX. Animals were followed up for 4 weeks. Acoustically evoked auditory brainstem response and impedance measurement, micro-computed tomography (µCT) imaging, and histology were performed for evaluation. RESULTS DEX was released for more than 250 days in vitro, with an initial burst followed by a slower release over time. Comparing the hearing threshold shift (from day 0 to day 28) of the CI and CI + RNI groups, significant differences were observed at 32 and 40 kHz. The impedance shift at basal contacts was lower in the CI + RNI group than in the CI group. Moreover, the fibrosis in the lower basal turn was reduced in the CI + RNI group in contrast to the CI group. CONCLUSIONS The RNI containing 10% DEX has anti-inflammatory potential concerning fibrosis inhibition and has beneficial effects on hearing preservation at high frequencies.
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Affiliation(s)
- Chunjiang Wei
- Department of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany; (C.W.); (Z.G.)
- Cluster of Excellence “Hearing4all”, German Research Foundation (DFG; “Deutsche Forschungsgemeinschaft”), Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
- Lower Saxony Center for Biomedical Engineering, Implant Research and Development (NIFE), Stadtfelddamm 34, 30625 Hannover, Germany
| | - Ziwen Gao
- Department of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany; (C.W.); (Z.G.)
- Cluster of Excellence “Hearing4all”, German Research Foundation (DFG; “Deutsche Forschungsgemeinschaft”), Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, Fudan University, Shanghai 200031, China
| | - Robert Mau
- Microfluidics, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, Justus-von-Liebig Weg 6, 18059 Rostock, Germany
| | - Thomas Eickner
- Institute for Biomedical Engineering, University Medical Center Rostock, University of Rostock, Friedrich-Barnewitz Straße 4, 18119 Rostock, Germany
| | - Gabor Jüttner
- Kunststoff-Zentrum in Leipzig gGmbH, Erich-Zeigner-Allee 44, 04229 Leipzig, Germany
| | - Nicklas Fiedler
- Institute for Biomedical Engineering, University Medical Center Rostock, University of Rostock, Friedrich-Barnewitz Straße 4, 18119 Rostock, Germany
| | - Hermann Seitz
- Microfluidics, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, Justus-von-Liebig Weg 6, 18059 Rostock, Germany
- Department Life, Light & Matter, Interdisciplinary Faculty, University of Rostock, Albert-Einstein-Str. 25, 18059 Rostock, Germany
| | - Thomas Lenarz
- Department of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany; (C.W.); (Z.G.)
- Cluster of Excellence “Hearing4all”, German Research Foundation (DFG; “Deutsche Forschungsgemeinschaft”), Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
- Lower Saxony Center for Biomedical Engineering, Implant Research and Development (NIFE), Stadtfelddamm 34, 30625 Hannover, Germany
| | - Verena Scheper
- Department of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany; (C.W.); (Z.G.)
- Cluster of Excellence “Hearing4all”, German Research Foundation (DFG; “Deutsche Forschungsgemeinschaft”), Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
- Lower Saxony Center for Biomedical Engineering, Implant Research and Development (NIFE), Stadtfelddamm 34, 30625 Hannover, Germany
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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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Nieratschker M, Yildiz E, Gerlitz M, Bera S, Gadenstaetter AJ, Kramer AM, Kwiatkowska M, Mistrik P, Landegger LD, Braun S, Schlingensiepen R, Honeder C, Arnoldner C, Rommelspacher H. A preoperative dose of the pyridoindole AC102 improves the recovery of residual hearing in a gerbil animal model of cochlear implantation. Cell Death Dis 2024; 15:531. [PMID: 39060244 PMCID: PMC11282255 DOI: 10.1038/s41419-024-06854-9] [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: 02/08/2024] [Revised: 06/19/2024] [Accepted: 06/20/2024] [Indexed: 07/28/2024]
Abstract
Sensorineural hearing loss (SNHL) is the most common sensory deficit worldwide. Due to the heterogeneity of causes for SNHL, effective treatment options remain scarce, creating an unmet need for novel drugs in the field of otology. Cochlear implantation (CI) currently is the only established method to restore hearing function in profound SNHL and deaf patients. The cochlear implant bypasses the non-functioning sensory hair cells (HCs) and electrically stimulates the neurons of the cochlear nerve. CI also benefits patients with residual hearing by combined electrical and auditory stimulation. However, the insertion of an electrode array into the cochlea induces an inflammatory response, characterized by the expression of pro-inflammatory cytokines, upregulation of reactive oxygen species, and apoptosis and necrosis of HCs, putting residual hearing at risk. Here, we characterize the small molecule AC102, a pyridoindole, for its protective effects on residual hearing in CI. In a gerbil animal model of CI, AC102 significantly improves the recovery of hearing thresholds across multiple frequencies and confines the cochlear trauma to the directly mechanically injured area. In addition, AC102 significantly preserves auditory nerve fibers and inner HC synapses throughout the whole cochlea. In vitro experiments in an ethanol challenged HT22 cell-line revealed significant and dose-responsive anti-apoptotic effects following the treatment of with AC102. Further, AC102 treatment resulted in significant downregulation of the expression of pro-inflammatory cytokines in an organotypic ex vivo model of electrode insertion trauma (EIT). These results suggest that AC102's effects are likely elicited during the inflammatory phase of EIT and mediated by anti-apoptotic and anti-inflammatory properties, highlighting AC102 as a promising compound for hearing preservation during CI. Moreover, since the inflammatory response in CI shares similarities to that in other etiologies of SNHL, AC102 may be inferred as a potential general treatment option for various inner ear conditions.
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Affiliation(s)
- Michael Nieratschker
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria
| | - Erdem Yildiz
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria
| | - Matthias Gerlitz
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria
| | | | - Anselm J Gadenstaetter
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria
| | - Anne-Margarethe Kramer
- Center for Biomedical Research and Translational Surgery, Medical University of Vienna, Vienna, Austria
| | | | | | - Lukas D Landegger
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria
| | | | | | - Clemens Honeder
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria
| | - Christoph Arnoldner
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria.
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Vecchi JT, Claussen AD, Hansen MR. Decreasing the physical gap in the neural-electrode interface and related concepts to improve cochlear implant performance. Front Neurosci 2024; 18:1425226. [PMID: 39114486 PMCID: PMC11303154 DOI: 10.3389/fnins.2024.1425226] [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: 04/29/2024] [Accepted: 07/11/2024] [Indexed: 08/10/2024] Open
Abstract
Cochlear implants (CI) represent incredible devices that restore hearing perception for those with moderate to profound sensorineural hearing loss. However, the ability of a CI to restore complex auditory function is limited by the number of perceptually independent spectral channels provided. A major contributor to this limitation is the physical gap between the CI electrodes and the target spiral ganglion neurons (SGNs). In order for CI electrodes to stimulate SGNs more precisely, and thus better approximate natural hearing, new methodologies need to be developed to decrease this gap, (i.e., transitioning CIs from a far-field to near-field device). In this review, strategies aimed at improving the neural-electrode interface are discussed in terms of the magnitude of impact they could have and the work needed to implement them. Ongoing research suggests current clinical efforts to limit the CI-related immune response holds great potential for improving device performance. This could eradicate the dense, fibrous capsule surrounding the electrode and enhance preservation of natural cochlear architecture, including SGNs. In the long term, however, optimized future devices will likely need to induce and guide the outgrowth of the peripheral process of SGNs to be in closer proximity to the CI electrode in order to better approximate natural hearing. This research is in its infancy; it remains to be seen which strategies (surface patterning, small molecule release, hydrogel coating, etc.) will be enable this approach. Additionally, these efforts aimed at optimizing CI function will likely translate to other neural prostheses, which face similar issues.
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Affiliation(s)
- Joseph T. Vecchi
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, Iowa City, IA, United States
- Department of Otolaryngology Head-Neck Surgery, Carver College of Medicine, Iowa City, IA, United States
| | - Alexander D. Claussen
- Department of Otolaryngology Head-Neck Surgery, Carver College of Medicine, Iowa City, IA, United States
| | - Marlan R. Hansen
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, Iowa City, IA, United States
- Department of Otolaryngology Head-Neck Surgery, Carver College of Medicine, Iowa City, IA, United States
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5
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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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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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Fleet A, Nikookam Y, Radotra A, Gowrishankar S, Metcalfe C, Muzaffar J, Smith ME, Monksfield P, Bance M. Outcomes following cochlear implantation with eluting electrodes: A systematic review. Laryngoscope Investig Otolaryngol 2024; 9:e1263. [PMID: 38855776 PMCID: PMC11160184 DOI: 10.1002/lio2.1263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 02/22/2024] [Accepted: 04/25/2024] [Indexed: 06/11/2024] Open
Abstract
Objectives To establish audiological and other outcomes following cochlear implantation in humans and animals with eluting electrodes. Methods Systematic review and narrative synthesis. Databases searched (April 2023): MEDLINE, EMBASE, CENTRAL, ClinicalTrials.gov, and Web of Science. Studies reporting outcomes in either humans or animals following cochlear implantation with a drug-eluting electrode were included. No limits were placed on language or year of publication. Risk of bias assessment was performed on all included studies using either the Brazzelli or Systematic Review Centre for Laboratory animal Experimentation (SYRCLE) assessment tools. The review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 statement. Results Searches identified 146 abstracts and 108 full texts. Of these, 18 studies met the inclusion criteria, reporting outcomes in 523 animals (17 studies) and 24 humans (1 study). Eluting electrodes included dexamethasone (16 studies), aracytine (1 study), nicotinamide adenine dinucleotide (1 study), the growth factors insulin-like growth factor 1 (IGF1) and hepatocyte growth factor (HGF) (1 study), and neurotrophin-3 (1 study). All included studies compare outcomes following implantation with an eluting electrode with a control non-eluting electrode. In the majority of studies, audiological outcomes (e.g., auditory brainstem response threshold) were superior following implantation with an eluting electrode compared with a standard electrode. Most studies which investigated post-implantation impedance reported lower impedance following implantation with an eluting electrode. The influence of eluting electrodes on other reported outcomes (including post-implantation cochlear fibrosis and the survival of hair cells and spiral ganglion neurons) was more varied across the included studies. Conclusions Eluting electrodes have shown promise in animal studies in preserving residual hearing following cochlear implantation and in reducing impedance, though data from human studies remain lacking. Further in-human studies will be required to determine the clinical usefulness of drug-eluting cochlear implants as a future treatment for sensorineural hearing loss.
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Affiliation(s)
- Alex Fleet
- Department of Clinical Neurosciences, Addenbrooke's Health CampusUniversity of CambridgeCambridgeUK
| | - Yasmin Nikookam
- Department of Ear, Nose and Throat SurgeryUniversity Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital Birmingham, Mindelsohn WayEdgbastonBirminghamUK
| | - Anshul Radotra
- The Royal Wolverhampton NHS Trust New Cross HospitalWolverhamptonUK
| | - Shravan Gowrishankar
- Department of Clinical Neurosciences, Addenbrooke's Health CampusUniversity of CambridgeCambridgeUK
| | | | - Jameel Muzaffar
- Department of Clinical Neurosciences, Addenbrooke's Health CampusUniversity of CambridgeCambridgeUK
- Department of Ear, Nose and Throat SurgeryUniversity Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital Birmingham, Mindelsohn WayEdgbastonBirminghamUK
| | - Matthew E. Smith
- Department of Clinical Neurosciences, Addenbrooke's Health CampusUniversity of CambridgeCambridgeUK
| | - Peter Monksfield
- Department of Ear, Nose and Throat SurgeryUniversity Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital Birmingham, Mindelsohn WayEdgbastonBirminghamUK
| | - Manohar Bance
- Department of Clinical Neurosciences, Addenbrooke's Health CampusUniversity of CambridgeCambridgeUK
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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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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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Fenov DM, Salcher R, Kludt E, Lesinski-Schiedat A, Harre J, Lenarz T, Giesemann A, Warnecke A. Long-term experience with biohybrid cochlear implants in human neurosensory restoration. Cochlear Implants Int 2024; 25:171-181. [PMID: 39159131 DOI: 10.1080/14670100.2024.2379124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/21/2024]
Abstract
OBJECTIVE The implantation of biohybrid electrodes was introduced a few years ago in our clinic. These electrodes coated with autologous mononuclear cells releasing anti-inflammatory and neuroprotective factors are thought to reduce insertion trauma and maintain the vitality of surviving spiral ganglion neurons. The clinical feasibility of this approach has already been demonstrated. In the present retrospective study, the four-year results of the two sides (classical electrode and biohybrid electrode) in the bilaterally implanted patients were compared in order to investigate possible adverse long-term effects. METHODS All patients received a complete audiological diagnosis which also included a speech audiogram and impedance measurement. The measurements were carried out 1 month, 3 months, 6 months, 1 year, 2 years, 3 years and 4 years after implantation. The hearing results were assessed by pure tone audiometry. RESULTS All patients showed satisfactory speech understanding and similar impedances on both sides although they had a long-term deafness before implantation of the side provided with a biohybrid electrode array. The results of speech understanding and impedance measurements were stable for years. Cone beam computed tomography was performed in 4 patients three years after implantation and could rule out cochlear ossification. Other complications were also not registered in any of the patients. CONCLUSION Due to satisfactory outcomes and lack of complications, the biohybrid electrode is considered to be a safe option in cochlear implantation. The simplicity of application of autologous cells as a source of anti-inflammatory and neuroprotective factors via a biohybrid electrode array is a key step for cell-based, regenerative therapies for deafness.
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Affiliation(s)
- Dragana Mitovska Fenov
- Department of Otolaryngology Head and Neck Surgery, Hannover Medical School, Hannover, Germany
| | - Rolf Salcher
- Department of Otolaryngology Head and Neck Surgery, Hannover Medical School, Hannover, Germany
| | - Eugen Kludt
- Department of Otolaryngology Head and Neck Surgery, Hannover Medical School, Hannover, Germany
| | - Anke Lesinski-Schiedat
- Department of Otolaryngology Head and Neck Surgery, Hannover Medical School, Hannover, Germany
| | - Jennifer Harre
- Department of Otolaryngology Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- Cluster of Excellence 'Hearing for All', German Research Foundation, Bonn, Germany
| | - Thomas Lenarz
- Department of Otolaryngology Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- Cluster of Excellence 'Hearing for All', German Research Foundation, Bonn, Germany
| | - Anja Giesemann
- Department for Diagnostic and Interventional Neuroradiology, Hannover Medical School, Hannover, Germany
| | - Athanasia Warnecke
- Department of Otolaryngology Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- Cluster of Excellence 'Hearing for All', German Research Foundation, Bonn, Germany
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11
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Razmovski T, Brody KM, Stathopoulos D, Zhang D, Cho E, Hampson AJ, Collins A, Bester C, O'Leary S. Intra-cochlear Flushing Reduces Tissue Response to Cochlear Implantation. Laryngoscope 2024; 134:1410-1416. [PMID: 37694764 DOI: 10.1002/lary.31022] [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: 03/15/2023] [Revised: 07/02/2023] [Accepted: 08/14/2023] [Indexed: 09/12/2023]
Abstract
INTRODUCTION Intraoperative trauma leading to bleeding during cochlear implantation negatively impacts residual hearing of cochlear implant recipients. There are no clinical protocols for the removal of blood during implantation, to reduce the consequential effects such as inflammation and fibrosis which adversely affect cochlear health and residual hearing. This preclinical study investigated the implementation of an intra-cochlear flushing protocol for the removal of blood. METHODS Three groups of guinea pigs were studied for 28 days after cochlear implantation; cochlear implant-only (control group); cochlear implant with blood injected into the cochlea (blood group); and cochlear implant, blood injection, and flushing of the blood from the cochlea intraoperatively (flush group). Auditory brainstem responses (ABRs) in addition to tissue response volumes were analyzed and compared between groups. RESULTS After implantation, the blood group exhibited the highest ABR thresholds when compared to the control and flush group, particularly in the high frequencies. On the final day, the control and blood group had similar ABR thresholds across all frequencies tested, whereas the flush group had the lowest thresholds, significantly lower at 24 kHz than the blood and control group. Analysis of the tissue response showed the flush group had significantly lower tissue responses in the basal half of the array when compared with the blood and control group. CONCLUSIONS Flushing intra-cochlear blood during surgery resulted in better auditory function and reduced subsequent fibrosis in the basal region of the cochlea. This finding prompts the implementation of a flushing protocol in clinical cochlear implantation. LEVEL OF EVIDENCE N/A Laryngoscope, 134:1410-1416, 2024.
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Affiliation(s)
- Tayla Razmovski
- Otolaryngology, Department of Surgery, Royal Victorian Eye and Ear Hospital, University of Melbourne, East Melbourne, Victoria, Australia
| | - Kate M Brody
- Otolaryngology, Department of Surgery, Royal Victorian Eye and Ear Hospital, University of Melbourne, East Melbourne, Victoria, Australia
| | - Dimitra Stathopoulos
- Otolaryngology, Department of Surgery, Royal Victorian Eye and Ear Hospital, University of Melbourne, East Melbourne, Victoria, Australia
| | - Dongcheng Zhang
- Otolaryngology, Department of Surgery, Royal Victorian Eye and Ear Hospital, University of Melbourne, East Melbourne, Victoria, Australia
| | - Ellie Cho
- Biological Optical Microscopy Platform, University of Melbourne, Parkville, Victoria, Australia
| | - Amy J Hampson
- Otolaryngology, Department of Surgery, Royal Victorian Eye and Ear Hospital, University of Melbourne, East Melbourne, Victoria, Australia
| | - Aaron Collins
- Otolaryngology, Department of Surgery, Royal Victorian Eye and Ear Hospital, University of Melbourne, East Melbourne, Victoria, Australia
| | - Christofer Bester
- Otolaryngology, Department of Surgery, Royal Victorian Eye and Ear Hospital, University of Melbourne, East Melbourne, Victoria, Australia
| | - Stephen O'Leary
- Otolaryngology, Department of Surgery, Royal Victorian Eye and Ear Hospital, University of Melbourne, East Melbourne, Victoria, Australia
- The Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia
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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; 25:131-139. [PMID: 38738388 DOI: 10.1080/14670100.2024.2338003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 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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13
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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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14
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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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15
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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: 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: 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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16
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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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Duan W, Poole-Warren L, Esrafilzadeh D, Robles UA. Effect of Hydrogel-based Model Fibrosis on Electrical Properties of Bioelectrodes. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023; 2023:1-4. [PMID: 38082779 DOI: 10.1109/embc40787.2023.10340104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
Fibrous tissue encapsulation can impact the performance of bioelectrodes following implantation. For example, significant increases in electrode impedance can occur within four weeks post-implantation. A key limitation hindering the understanding of host response-mediated impedance change is the reliance on animal models or complex in vitro cell cultures for electrode testing. This study aimed to develop an in vitro acellular model that can reproduce the changes in electrical properties of bioelectrodes that occur due to host responses following implantation. Specifically, the effect of synthetic, biological, and bio-synthetic co-polymer hydrogel coatings on electrode impedance was measured. Poly(vinyl alcohol) (PVA), gelatin, and PVA-gelatin co-polymers (10 and 20 wt%) were coated onto platinum (Pt) electrodes. Polarisation and access voltage, key components of the voltage response that relate to cell adhesion and protein adsorption respectively, were measured pre and post hydrogel coating and the impedance change was calculated. Results showed that increasing the polymer concentration affects the access resistance regardless of the hydrogel chemistry but only high content gelatin hydrogels increased the polarisation resistance. The increase in total impedance was ~ 2-fold of bare Pt, similar to clinical observations. This study demonstrated that an acellular fibrosis model using hydrogels could reproduce the impedance changes observed in vivo. Such a model system will support research to better understand in vivo changes in electrical properties and the longer term function of neuroprosthetic electrodes.Clinical Relevance-This study proposes an acellular fibrosis model for preclinical research. This will support the design of improved clinical stimulation strategies and better understanding of the mechanisms of impedance change at the device-tissue interface.
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18
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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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19
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Evaluation of the hearing preservation and tissue response of dexamethasone and hyaluronic acid delivery during cochlear implantation on cats in a three-month period study. Auris Nasus Larynx 2023; 50:228-234. [PMID: 35879150 DOI: 10.1016/j.anl.2022.07.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 06/17/2022] [Accepted: 07/08/2022] [Indexed: 11/23/2022]
Abstract
OBJECTIVE To evaluate the effects of DX and HA on hearing preservation and tissue response with cochlear implantation in a cat mode. METHODS 11 cats were bilaterally implanted with Nurotron electrode. According to the different treatment, 22 ears were subdivided into four following groups: Electrode (E) only, Electrode +HA (E+H), Electrode + DX (E+DX), and Electrode +HA +DX (E+H+DX). Auditory brainstem responses (ABR) thresholds were recorded before and 3 months after surgery. After 3 months of cochlear implantation histopathological assessment of all cochleae were performed . RESULTS At low frequencies, the mean ABR thresholds shift in animals treated with E+H+DX demonstrated a statistically significant difference. The proportion of cochleae showing fibrous tissue and new bone formation was 50% in E+H+DX group, 66.7% in E+DX group, 83.3% in E+H group and 100% in E group. CONCLUSION United HA and DX local delivery could provide better protection against hearing loss at low-frequency threshold and could more effectively reduce the trauma related to electrode insertion and the fibrous tissue formation around the electrode.
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20
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Schuerch K, Wimmer W, Dalbert A, Rummel C, Caversaccio M, Mantokoudis G, Gawliczek T, Weder S. An intracochlear electrocochleography dataset - from raw data to objective analysis using deep learning. Sci Data 2023; 10:157. [PMID: 36949075 PMCID: PMC10033652 DOI: 10.1038/s41597-023-02055-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 03/08/2023] [Indexed: 03/24/2023] Open
Abstract
Electrocochleography (ECochG) measures electrophysiological inner ear potentials in response to acoustic stimulation. These potentials reflect the state of the inner ear and provide important information about its residual function. For cochlear implant (CI) recipients, we can measure ECochG signals directly within the cochlea using the implant electrode. We are able to perform these recordings during and at any point after implantation. However, the analysis and interpretation of ECochG signals are not trivial. To assist the scientific community, we provide our intracochlear ECochG data set, which consists of 4,924 signals recorded from 46 ears with a cochlear implant. We collected data either immediately after electrode insertion or postoperatively in subjects with residual acoustic hearing. This data descriptor aims to provide the research community access to our comprehensive electrophysiological data set and algorithms. It includes all steps from raw data acquisition to signal processing and objective analysis using Deep Learning. In addition, we collected subject demographic data, hearing thresholds, subjective loudness levels, impedance telemetry, radiographic findings, and classification of ECochG signals.
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Affiliation(s)
- Klaus Schuerch
- Department of ENT, Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Wilhelm Wimmer
- Department of ENT, Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Adrian Dalbert
- Department of Otorhinolaryngology, Head&Neck Surgery, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Christian Rummel
- Support Center for Advanced Neuroimaging (SCAN), University Institute for Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Marco Caversaccio
- Department of ENT, Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Georgios Mantokoudis
- Department of ENT, Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Tom Gawliczek
- 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.
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland.
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21
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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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22
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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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23
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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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24
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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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25
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Bester C, Collins A, Razmovski T, Weder S, Briggs RJ, Wei B, Zakaria AF, Gerard JM, Mitchell-Innes A, Tykocinski M, Kennedy R, Iseli C, Dahm M, Ellul S, O'Leary S. Electrocochleography triggered intervention successfully preserves residual hearing during cochlear implantation: Results of a randomised clinical trial. Hear Res 2022; 426:108353. [PMID: 34600798 DOI: 10.1016/j.heares.2021.108353] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/19/2021] [Accepted: 09/15/2021] [Indexed: 12/16/2022]
Abstract
BACKGROUND Preservation of natural hearing during cochlear implantation is associated with improved speech outcomes, however more than half of implant recipients lose this hearing. Real-time electrophysiological monitoring of cochlear output during implantation, made possible by recording electrocochleography using the electrodes on the cochlear implant, has shown promise in predicting hearing preservation. Sudden drops in the amplitude of the cochlear microphonic (CM) have been shown to predict more severe hearing losses. Here, we report on a randomized clinical trial investigating whether immediate surgical intervention triggered by these drops can save residual hearing. METHODS A single-blinded placebo-controlled trial of surgical intervention triggered when CM amplitude dropped by at least 30% of a prior maximum amplitude during cochlear implantation. Intraoperative electrocochleography was recorded in 60 adults implanted with Cochlear Ltd's Thin Straight Electrode, half randomly assigned to a control group and half to an interventional group. The surgical intervention was to withdraw the electrode in ½-mm steps to recover CM amplitude. The primary outcome was hearing preservation 3 months following implantation, with secondary outcomes of speech-in-noise reception thresholds by group or CM outcome, and depth of implantation. RESULTS Sixty patients were recruited; neither pre-operative audiometry nor speech reception thresholds were significantly different between groups. Post-operatively, hearing preservation was significantly better in the interventional group. This was the case in absolute difference (median of 30 dB for control, 20 dB for interventional, χ² = 6.2, p = .013), as well as for relative difference (medians of 66% for the control, 31% for the interventional, χ² = 5.9, p = .015). Speech-in-noise reception thresholds were significantly better in patients with no CM drop at any point during insertion compared with patients with a CM drop; however, those with successfully recovered CMs after an initial drop were not significantly different (median gain required for speech reception score of 50% above noise of 6.9 dB for no drop, 8.6 for recovered CM, and 9.8 for CM drop, χ² = 6.8, p = .032). Angular insertion depth was not significantly different between control and interventional groups. CONCLUSIONS This is the first demonstration that surgical intervention in response to intraoperative hearing monitoring can save residual hearing during cochlear implantation.
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Affiliation(s)
- Christofer Bester
- The University of Melbourne, Department of Surgery and The Royal Victorian Eye and Ear Hospital.
| | - Aaron Collins
- The University of Melbourne, Department of Surgery and The Royal Victorian Eye and Ear Hospital
| | - Tayla Razmovski
- The University of Melbourne, Department of Surgery and The Royal Victorian Eye and Ear Hospital
| | - Stefan Weder
- The University of Melbourne, Department of Surgery and The Royal Victorian Eye and Ear Hospital; Department of ENT, Head and Neck Surgery, University Hospital, Bern, Switzerland
| | | | | | - Atiqah Farah Zakaria
- The University of Melbourne, Department of Surgery and The Royal Victorian Eye and Ear Hospital; Department of Otorhinolaryngology, University Putra Malaysia, Malaysia
| | - Jean-Marc Gerard
- The University of Melbourne, Department of Surgery and The Royal Victorian Eye and Ear Hospital; Department of ENT, RVEEH
| | - Alistair Mitchell-Innes
- The University of Melbourne, Department of Surgery and The Royal Victorian Eye and Ear Hospital; Department of ENT, RVEEH
| | | | | | | | | | | | - Stephen O'Leary
- The University of Melbourne, Department of Surgery and The Royal Victorian Eye and Ear Hospital; Department of ENT, RVEEH.
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D’Alessandro S, Handler M, Saba R, Garnham C, Baumgarten D. Computer Simulation of the Electrical Stimulation of the Human Vestibular System: Effects of the Reactive Component of Impedance on Voltage Waveform and Nerve Selectivity. J Assoc Res Otolaryngol 2022; 23:815-833. [PMID: 36050508 PMCID: PMC9789245 DOI: 10.1007/s10162-022-00868-w] [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: 12/22/2021] [Accepted: 08/13/2022] [Indexed: 01/06/2023] Open
Abstract
The vestibular system is responsible for our sense of balance and spatial orientation. Recent studies have shown the possibility of partially restoring the function of this system using vestibular implants. Electrical modeling is a valuable tool in assisting the development of these implants by analyzing stimulation effects. However, previous modeling approaches of the vestibular system assumed quasi-static conditions. In this work, an extended modeling approach is presented that considers the reactive component of impedance and the electrode-tissue interface and their effects are investigated in a 3D human vestibular computer model. The Fourier finite element method was employed considering the frequency-dependent electrical properties of the different tissues. The electrode-tissue interface was integrated by an instrumental electrode model. A neuron model of myelinated fibers was employed to predict the nerve responses to the electrical stimulus. Morphological changes of the predicted voltage waveforms considering the dielectric tissue properties were found compared to quasi-static simulations, particularly during monopolar electrode configuration. Introducing the polarization capacitance and the scar tissue around the electrode in combination with a power limitation leads to a considerable current reduction applied through the active electrode and, consequently, to reduced voltage amplitudes of the stimulus waveforms. The reactive component of impedance resulted in better selectivity for the excitation of target nerves compared to the quasi-static simulation at the expense of slightly increased stimulus current amplitudes. We conclude that tissue permittivity and effects of the electrode-tissue interface should be considered to improve the accuracy of the simulations.
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Affiliation(s)
- Simone D’Alessandro
- Institute of Electrical and Biomedical Engineering, UMIT - Private University for Health Sciences, Medical Informatics and Technology, Hall in Tirol, Austria
| | - Michael Handler
- Institute of Electrical and Biomedical Engineering, UMIT - Private University for Health Sciences, Medical Informatics and Technology, Hall in Tirol, Austria
| | | | | | - Daniel Baumgarten
- Institute of Electrical and Biomedical Engineering, UMIT - Private University for Health Sciences, Medical Informatics and Technology, Hall in Tirol, Austria
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27
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The Augmented Cochlear Implant: a Convergence of Drugs and Cochlear Implantation for the Treatment of Hearing Loss. CURRENT OTORHINOLARYNGOLOGY REPORTS 2022. [DOI: 10.1007/s40136-022-00426-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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28
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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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29
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Wimmer W, Sclabas L, Caversaccio M, Weder S. Cochlear Implant Electrode Impedance as Potential Biomarker for Residual Hearing. Front Neurol 2022; 13:886171. [PMID: 35832176 PMCID: PMC9271767 DOI: 10.3389/fneur.2022.886171] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 05/31/2022] [Indexed: 11/13/2022] Open
Abstract
Introduction and ObjectivesAmong cochlear implant candidates, an increasing number of patients are presenting with residual acoustic hearing. To monitor the postoperative course of structural and functional preservation of the cochlea, a reliable objective biomarker would be desirable. Recently, impedance telemetry has gained increasing attention in this field. The aim of this study was to investigate the postoperative course of the residual acoustic hearing and clinical impedance in patients with long electrode arrays and to explore the applicability of impedance telemetry for monitoring residual hearing.MethodsWe retrospectively analyzed records of 42 cochlear implant recipients with residual hearing covering a median postoperative follow-up of 25 months with repeated simultaneous pure tone audiometry and impedance telemetry. We used a linear mixed-effects model to estimate the relation between clinical electrode impedance and residual hearing. Besides the clinical impedance, the follow-up time, side of implantation, gender, and age at implantation were included as fixed effects. An interaction term between impedance and follow-up time, as well as subject-level random intercepts and slopes, were included.ResultsLoss of residual hearing occurred either during surgery or within the first 6 post-operative months. Electrode contacts inserted further apically (i.e., deeper) had higher impedances, independent of residual hearing. The highest impedances were measured 1 month postoperatively and gradually decreased over time. Basal electrodes were more likely to maintain higher impedance. Follow-up time was significantly associated with residual hearing. Regardless of the time, we found that a 1 kΩ increase in clinical impedance was associated with a 4.4 dB deterioration of residual hearing (p < 0.001).ConclusionPure tone audiometry is the current gold standard for monitoring postoperative residual hearing. However, the association of clinical impedances with residual hearing thresholds found in our study could potentially be exploited for objective monitoring using impedance telemetry. Further analysis including near-field related impedance components could be performed for improved specificity to local immune responses.
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Affiliation(s)
- Wilhelm Wimmer
- 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
- *Correspondence: Wilhelm Wimmer
| | - Luca Sclabas
- 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
| | - Stefan Weder
- 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
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30
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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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Hodge SE, Ishiyama G, Lopez IA, Ishiyama A. Histopathologic Analysis of Temporal Bones With Otosclerosis Following Cochlear Implantation. Otol Neurotol 2021; 42:1492-1498. [PMID: 34607995 PMCID: PMC8595606 DOI: 10.1097/mao.0000000000003327] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Analyze changes in osteoneogenesis and fibrosis following cochlear implant (CI) surgery in patients with otosclerosis and compare differences based on insertion technique. BACKGROUND When advanced otosclerotic disease extends to the otic capsule, severe and profound sensorineural hearing loss necessitates consideration of a cochlear implant. Histopathological analysis of the human temporal bone after implantation in the patient with otosclerosis may reveal important variables that predict CI success. METHODS Histopathological evaluation of archival human temporal bones from subjects with a history of CI for cochlear otosclerosis. A total of 17 human temporal bones (HTB) were analyzed, 13 implanted, and 4 contralateral non-implanted controls. RESULTS Histopathological studies revealed extensive osteoneogenesis and fibrosis which was more prominent at the cochleostomy insertion site in the basal turn of the cochlea often obliterating the scala tympani in the basal turn, and in some cases extending to the scala media and scala vestibuli. Cochlear hydrops was nearly universal in these cases. This contrasted with the round window insertion, which exhibited minimal osteoneogenesis within the cochlear duct. In addition, in the contralateral, unimplanted control ears, there was otosclerosis at the stapes footplate, fissula ante fenestrum but no osteoneogenesis within the cochlear duct. CONCLUSION Cochleostomy approach to CI insertion in otosclerosis patients is associated with significant fibrosis, osteoneogenesis, and cochlear hydrops. A round window insertion technique can be utilized to help minimize these histopathologic findings whenever feasible.
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Affiliation(s)
| | - Gail Ishiyama
- Department of Neurology, David Geffen School of Medicine at UCLA
| | - Ivan A Lopez
- Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Akira Ishiyama
- Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California
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Chen D, Luo Y, Pan J, Chen A, Ma D, Xu M, Tang J, Zhang H. Long-Term Release of Dexamethasone With a Polycaprolactone-Coated Electrode Alleviates Fibrosis in Cochlear Implantation. Front Cell Dev Biol 2021; 9:740576. [PMID: 34778254 PMCID: PMC8589109 DOI: 10.3389/fcell.2021.740576] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 09/28/2021] [Indexed: 01/13/2023] Open
Abstract
Cochlear implantation (CI) is the major treatment for severe sensorineural hearing loss. However, the fibrotic tissue forming around the electrodes reduces the treatment effectiveness of CI. Dexamethasone (DEX) is usually applied routinely in perioperative treatment of cochlear implantation (CI), but its diffusion in the inner ear after systemic administration is limited. In the present study, an electrode coated with polycaprolactone (PCL) loaded with dexamethasone was developed with a simple preparation process to maintain the stability of the electrode itself. The DEX-loaded PCL coating has good biocompatibility and does not change the smoothness, flexibility, or compliance of the implant electrode. Stable and effective DEX concentrations were maintained for more than 9 months. Compared with the pristine electrode, decreasing intracochlear fibrosis, protection of hair cells and spiral ganglion cells, and better residual hearing were observed 5 weeks after PCL-DEX electrode implantation. The PCL-DEX electrode has great potential in preventing hearing loss and fibrosis by regulating macrophages and inhibiting the expression of the fibrosis-related factors IL-1β, TNF-α, IL-4, and TGF-β1. In conclusion, the PCL-DEX electrode coating shows promising application in CI surgery.
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Affiliation(s)
- Dongxiu Chen
- Department of Otolaryngology Head and Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Hearing Research Center, Southern Medical University, Guangzhou, China
| | - Yanjing Luo
- Department of Otolaryngology Head and Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Hearing Research Center, Southern Medical University, Guangzhou, China
| | - Jing Pan
- Department of Otolaryngology Head and Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Hearing Research Center, Southern Medical University, Guangzhou, China
| | - Anning Chen
- Department of Otolaryngology Head and Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Hearing Research Center, Southern Medical University, Guangzhou, China
| | - Dong Ma
- Key Laboratory of Biomaterials of Guangdong Higher Education Institutes, Department of Biomedical Engineering, Jinan University, Guangzhou, China
| | - Muqing Xu
- Department of Otolaryngology Head and Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Hearing Research Center, Southern Medical University, Guangzhou, China
| | - Jie Tang
- Hearing Research Center, Southern Medical University, Guangzhou, China.,Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China.,Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, China
| | - Hongzheng Zhang
- Department of Otolaryngology Head and Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Hearing Research Center, Southern Medical University, Guangzhou, China
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Turnbull L, Leigh R, Cavaliere R, Osvath SR, Nolan LM, Smyth D, Verhoeven K, Chole RA, Whitchurch CB. Device Design Modifications Informed by In Vitro Testing of Bacterial Attachment Reduce Infection Rates of Cochlear Implants in Clinical Practice. Microorganisms 2021; 9:1809. [PMID: 34576704 PMCID: PMC8471994 DOI: 10.3390/microorganisms9091809] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 07/28/2021] [Accepted: 08/20/2021] [Indexed: 11/17/2022] Open
Abstract
Recalcitrant chronic infections of implanted medical devices are often linked to the presence of biofilms. The prevention and treatment of medical device-associated infections is a major source of antibiotic use and driver of antimicrobial resistance globally. Lowering the incidence of infection in patients that receive implanted medical devices could therefore significantly improve antibiotic stewardship and reduce patient morbidity. Here we determined if modifying the design of an implantable medical device to reduce bacterial attachment, impacted the incidence of device-associated infections in clinical practice. Since the 1980s cochlear implants have provided long-term treatment of sensorineural hearing deficiency in hundreds of thousands of patients world-wide. Nonetheless, a relatively small number of devices are surgically explanted each year due to unresolvable infections. Features associated with the accumulation of bacteria on the Cochlear™ Nucleus® CI24RE™ model of cochlear implant devices were identified using both in vitro bacterial attachment assays and examination of explanted devices. Macro-scale design modifications that reduced bacterial attachment in vitro were incorporated into the design of the CI500™ and Profile™ series of Nucleus implant. Analyses of mandatory post-market vigilance data of 198,757 CI24RE and 123,084 CI500/Profile series implantation surgeries revealed that these design modifications correlated with significantly reduced infection rates. This study demonstrates that a design-centric approach aimed at mitigating bacterial attachment was a simple, and effective means of reducing infections associated with Cochlear Nucleus devices. This approach is likely to be applicable to improving the designs of other implantable medical devices to reduce device-associated infections.
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Affiliation(s)
- Lynne Turnbull
- The iThree Institute, University of Technology Sydney, Ultimo, NSW 2007, Australia; (L.T.); (R.C.); (S.R.O.)
| | - Roger Leigh
- Cochlear Limited, 1 University Avenue, Macquarie University, Sydney, NSW 2109, Australia; (R.L.); (D.S.); (K.V.)
| | - Rosalia Cavaliere
- The iThree Institute, University of Technology Sydney, Ultimo, NSW 2007, Australia; (L.T.); (R.C.); (S.R.O.)
| | - Sarah R. Osvath
- The iThree Institute, University of Technology Sydney, Ultimo, NSW 2007, Australia; (L.T.); (R.C.); (S.R.O.)
| | - Laura M. Nolan
- National Heart and Lung Institute, Imperial College London, London SW3 6LR, UK;
| | - Daniel Smyth
- Cochlear Limited, 1 University Avenue, Macquarie University, Sydney, NSW 2109, Australia; (R.L.); (D.S.); (K.V.)
| | - Kristien Verhoeven
- Cochlear Limited, 1 University Avenue, Macquarie University, Sydney, NSW 2109, Australia; (R.L.); (D.S.); (K.V.)
| | - Richard A. Chole
- Washington School of Medicine in St Louis, Washington University in St. Louis, St. Louis, MO 63110, USA;
| | - Cynthia B. Whitchurch
- The iThree Institute, University of Technology Sydney, Ultimo, NSW 2007, Australia; (L.T.); (R.C.); (S.R.O.)
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TK, UK
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Danielian A, Ishiyama G, Lopez IA, Ishiyama A. Predictors of Fibrotic and Bone Tissue Formation With 3-D Reconstructions of Post-implantation Human Temporal Bones. Otol Neurotol 2021; 42:e942-e948. [PMID: 33710156 PMCID: PMC8282738 DOI: 10.1097/mao.0000000000003106] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
HYPOTHESIS Years of implantation, surgical insertion approach, and electrode length will impact the volume of new tissue formation secondary to cochlear implantation. BACKGROUND New tissue formation, fibrosis, and osteoneogenesis after cochlear implantation have been implicated in increasing impedance and affecting performance of the cochlear implant. METHODS 3-D reconstructions of 15 archival human temporal bones from patients with a history of cochlear implantation (CI) were generated from H&E histopathologic slides to study factors which affect volume of tissue formation. RESULTS Years of implantation was a predictor of osteoneogenesis (r = 0.638, p-value = 0.011) and total new tissue formation (r = 0.588, p-value = 0.021), however not of fibrosis (r = 0.235, p-value = 0.399). Median total tissue formation differed between cochleostomy and round window insertions, 25.98 and 10.34%, respectively (Mann-Whitney U = 7, p = 0.018). No correlations were found between electrode length or angular insertion depth and total new tissue (p = 0.192, p = 0.35), osteoneogenesis (p = 0.193, p = 0.27), and fibrosis (p = 0.498, p = 0.83), respectively. However, the type II error for electrode length and angular insertion depth ranged from 0.73 to 0.90, largely due to small numbers of the shorter electrodes. CONCLUSIONS With numbers of cochlear implant recipients increasing worldwide, an understanding of how to minimize intracochlear changes from implantation is important. The present study demonstrates that increasing years of implantation and inserting electrodes via a cochleostomy compared with a round window approach are associated with significantly greater degree of new tissue volume formation. While previous studies have demonstrated increased intracochlear damage in the setting of translocation with longer electrodes, length, and angular insertion depth of CI electrodes were not associated with increased tissue formation.
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Affiliation(s)
- Arman Danielian
- UCLA David Geffen School of Medicine Department of Head and Neck Surgery, Los Angeles, CA, 90095, USA
| | - Gail Ishiyama
- UCLA David Geffen School of Medicine Department of Neurology, Los Angeles, CA, 90095, USA
| | - Ivan A Lopez
- UCLA David Geffen School of Medicine Department of Head and Neck Surgery, Los Angeles, CA, 90095, USA
| | - Akira Ishiyama
- UCLA David Geffen School of Medicine Department of Head and Neck Surgery, Los Angeles, CA, 90095, USA
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Toulemonde P, Risoud M, Lemesre PE, Beck C, Wattelet J, Tardivel M, Siepmann J, Vincent C. Evaluation of the Efficacy of Dexamethasone-Eluting Electrode Array on the Post-Implant Cochlear Fibrotic Reaction by Three-Dimensional Immunofluorescence Analysis in Mongolian Gerbil Cochlea. J Clin Med 2021; 10:jcm10153315. [PMID: 34362099 PMCID: PMC8347204 DOI: 10.3390/jcm10153315] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 07/22/2021] [Accepted: 07/26/2021] [Indexed: 11/16/2022] Open
Abstract
Cochlear implant is the method of choice for the rehabilitation of severe to profound sensorineural hearing loss. The study of the tissue response to cochlear implantation and the prevention of post-cochlear-implant damages are areas of interest in hearing protection research. The objective was to assess the efficacy of dexamethasone-eluting electrode array on endo canal fibrosis formation by three-dimensional immunofluorescence analysis in implanted Mongolian gerbil cochlea. Two trials were conducted after surgery using Mongolian gerbil implanted with dexamethasone-eluting or non-eluting intracochlear electrode arrays. The animals were then euthanised 10 weeks after implantation. The cochleae were prepared (electrode array in place) according to a 29-day protocol with immunofluorescent labelling and tissue clearing. The acquisition was carried out using light-sheet microscopy. Imaris software was then used for three-dimensional analysis of the cochleae and quantification of the fibrotic volume. The analysis of 12 cochleae showed a significantly different mean volume of fibrosis (2.16 × 108 μm3 ± 0.15 in the dexamethasone eluting group versus 3.17 × 108 μm3 ± 0.54 in the non-eluting group) (p = 0.004). The cochlear implant used as a corticosteroid delivery system appears to be an encouraging device for the protection of the inner ear against fibrosis induced by implantation. Three-dimensional analysis of the cochlea by light-sheet microscopy was suitable for studying post-implantation tissue damage.
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Affiliation(s)
- Philippine Toulemonde
- Department of Otology and Neurotology, CHU Lille, University of Lille 2 Henri Warembourg, F-59000 Lille, France; (M.R.); (P.E.L.); (C.B.); (J.W.); (J.S.); (C.V.)
- INSERM U1008—Controlled Drug Delivery Systems and Biomaterials, F-59000 Lille, France
- Correspondence: ; Tel.: +33-6851-91052
| | - Michaël Risoud
- Department of Otology and Neurotology, CHU Lille, University of Lille 2 Henri Warembourg, F-59000 Lille, France; (M.R.); (P.E.L.); (C.B.); (J.W.); (J.S.); (C.V.)
- INSERM U1008—Controlled Drug Delivery Systems and Biomaterials, F-59000 Lille, France
| | - Pierre Emmanuel Lemesre
- Department of Otology and Neurotology, CHU Lille, University of Lille 2 Henri Warembourg, F-59000 Lille, France; (M.R.); (P.E.L.); (C.B.); (J.W.); (J.S.); (C.V.)
- INSERM U1008—Controlled Drug Delivery Systems and Biomaterials, F-59000 Lille, France
| | - Cyril Beck
- Department of Otology and Neurotology, CHU Lille, University of Lille 2 Henri Warembourg, F-59000 Lille, France; (M.R.); (P.E.L.); (C.B.); (J.W.); (J.S.); (C.V.)
- INSERM U1008—Controlled Drug Delivery Systems and Biomaterials, F-59000 Lille, France
| | - Jean Wattelet
- Department of Otology and Neurotology, CHU Lille, University of Lille 2 Henri Warembourg, F-59000 Lille, France; (M.R.); (P.E.L.); (C.B.); (J.W.); (J.S.); (C.V.)
- INSERM U1008—Controlled Drug Delivery Systems and Biomaterials, F-59000 Lille, France
| | - Meryem Tardivel
- BioImaging Center Lille-Nord de France (BICeL), University of Lille 2 Henri Warembourg, F-59000 Lille, France;
| | - Juergen Siepmann
- Department of Otology and Neurotology, CHU Lille, University of Lille 2 Henri Warembourg, F-59000 Lille, France; (M.R.); (P.E.L.); (C.B.); (J.W.); (J.S.); (C.V.)
- INSERM U1008—Controlled Drug Delivery Systems and Biomaterials, F-59000 Lille, France
| | - Christophe Vincent
- Department of Otology and Neurotology, CHU Lille, University of Lille 2 Henri Warembourg, F-59000 Lille, France; (M.R.); (P.E.L.); (C.B.); (J.W.); (J.S.); (C.V.)
- INSERM U1008—Controlled Drug Delivery Systems and Biomaterials, F-59000 Lille, France
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Fröhlich L, Wilke M, Plontke SK, Rahne T. Bone conducted vibration is an effective stimulus for otolith testing in cochlear implant patients. J Vestib Res 2021; 32:355-365. [PMID: 34308918 PMCID: PMC9398058 DOI: 10.3233/ves-210028] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Treatment with a cochlear implant (CI) poses the risk of inducing a behaviorally unmeasurable air-bone gap leading to false negative absence of cervical and ocular vestibular evoked myogenic potentials (cVEMPs, oVEMPs) to air conducted sound (ACS). OBJECTIVE To investigate VEMP response rates to ACS and bone conducted vibration (BCV) in CI patients and the applicability of the B81 transducer for BCV stimulation. METHODS Prospective experimental study including unilateral CI patients, measuring cVEMPs and oVEMPs to ACS and to BCV, comparing response rates, signed asymmetry ratios, latencies, and amplitudes. RESULTS Data of 13 CI patients (mean age 44±12 years) were analyzed. For the CI side, oVEMP and cVEMP response rates were significantly higher for BCV (77%cVEMP, 62%oVEMP) compared to ACS (23%cVEMP, 8%oVEMP). For the contralateral side, no difference between response rates to ACS (85%cVEMP, 69%oVEMP) and BCV (85%cVEMP, 77%oVEMP) was observed. Substantially higher asymmetries were observed for ACS (-88±23%for cVEMPs, -96±11%for oVEMPs) compared to BCV (-12±45%for cVEMPs, 4±74%for oVEMPs). CONCLUSIONS BCV is an effective stimulus for VEMP testing in CI patients. The B81 is a feasible stimulator.
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Affiliation(s)
- L Fröhlich
- Department of Otorhinolaryngology, Head & NeckSurgery, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - M Wilke
- Department of Otorhinolaryngology, Head & NeckSurgery, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - S K Plontke
- Department of Otorhinolaryngology, Head & NeckSurgery, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - T Rahne
- Department of Otorhinolaryngology, Head & NeckSurgery, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
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Merchant GR, Schulz KM, Patterson JN, Fitzpatrick D, Janky KL. Effect of Cochlear Implantation on Vestibular Evoked Myogenic Potentials and Wideband Acoustic Immittance. Ear Hear 2021; 41:1111-1124. [PMID: 32032225 PMCID: PMC7392788 DOI: 10.1097/aud.0000000000000831] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVES The objective of this study was to determine if absent air conduction stimuli vestibular evoked myogenic potential (VEMP) responses found in ears after cochlear implantation can be the result of alterations in peripheral auditory mechanics rather than vestibular loss. Peripheral mechanical changes were investigated by comparing the response rates of air and bone conduction VEMPs as well as by measuring and evaluating wideband acoustic immittance (WAI) responses in ears with cochlear implants and normal-hearing control ears. The hypothesis was that the presence of a cochlear implant can lead to an air-bone gap, causing absent air conduction stimuli VEMP responses, but present bone conduction vibration VEMP responses (indicating normal vestibular function), with changes in WAI as compared with ears with normal hearing. Further hypotheses were that subsets of ears with cochlear implants would (a) have present VEMP responses to both stimuli, indicating normal vestibular function and either normal or near-normal WAI, or (b) have absent VEMP responses to both stimuli, regardless of WAI, due to true vestibular loss. DESIGN Twenty-seven ears with cochlear implants (age range 7 to 31) and 10 ears with normal hearing (age range 7 to 31) were included in the study. All ears completed otoscopy, audiometric testing, 226 Hz tympanometry, WAI measures (absorbance), air conduction stimuli cervical and ocular VEMP testing through insert earphones, and bone conduction vibration cervical and ocular VEMP testing with a mini-shaker. Comparisons of VEMP responses to air and bone conduction stimuli, as well as absorbance responses between ears with normal hearing and ears with cochlear implants, were completed. RESULTS All ears with normal hearing demonstrated 100% present VEMP response rates for both stimuli. Ears with cochlear implants had higher response rates to bone conduction vibration compared with air conduction stimuli for both cervical and ocular VEMPs; however, this was only significant for ocular VEMPs. Ears with cochlear implants demonstrated reduced low-frequency absorbance (500 to 1200 Hz) as compared with ears with normal hearing. To further analyze absorbance, ears with cochlear implants were placed into subgroups based on their cervical and ocular VEMP response patterns. These groups were (1) present air conduction stimuli response, present bone conduction vibration response, (2) absent air conduction stimuli response, present bone conduction vibration response, and (3) absent air conduction stimuli response, absent bone conduction vibration response. For both cervical and ocular VEMPs, the group with absent air conduction stimuli responses and present bone conduction vibration responses demonstrated the largest decrease in low-frequency absorbance as compared with the ears with normal hearing. CONCLUSIONS Bone conduction VEMP response rates were increased compared with air-conduction VEMP response rates in ears with cochlear implants. Ears with cochlear implants also demonstrate changes in low-frequency absorbance consistent with a stiffer system. This effect was largest for ears that had absent air conduction but present bone conduction VEMPs. These findings suggest that this group, in particular, has a mechanical change that could lead to an air-bone gap, thus, abolishing the air conduction VEMP response due to an alteration in mechanics and not a true vestibular loss. Clinical considerations include using bone conduction vibration VEMPs and WAI for preoperative and postoperative testing in patients undergoing cochlear implantation.
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Affiliation(s)
| | - Kyli M. Schulz
- Boys Town National Research Hospital, Omaha, NE 68131
- The University of Texas at Austin, TX 78712
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Abstract
HYPOTHESIS Animals with cochlear implantation-induced hearing loss will have a lower endocochlear potential (EP) and decreased strial vascular density. BACKGROUND The cause of residual hearing loss following cochlear implantation remains poorly understood. Recent work from our lab has shown a correlation between vascular changes in the cochlear lateral wall and postimplantation hearing loss, suggesting a role of the stria vascularis and EP. METHODS Fourteen young, normal-hearing male albino guinea pigs underwent cochlear implantation using either a cochleostomy (CI-c, n = 9) or an extended round window (CI-eRW, n = 5) approach. Hearing sensitivity was assessed pre- and postoperatively using auditory brainstem response thresholds. Three weeks after implantation, EP measurements were obtained from the first and second turns. Hair cell counts and stria vascularis capillary density measurements were also obtained. RESULTS The implanted group experienced significant threshold elevations at 8 to 24 kHz (mean threshold shift 9.1 ± 1.1 dB), with a more robust threshold shift observed in the CI-eRW group compared to the CI-c group. Implanted animals had a significantly lower first turn EP (81.4 ± 5.1 mV) compared with controls (87.9 ± 6.1 mV). No differences were observed in the second turn (75.8 ± 12.0 mV for implanted animals compared to 76.5 ± 7.0 mV for controls). There were no significant correlations between turn-specific threshold shifts, EP measurements, or strial blood vessel density. CONCLUSIONS Reliable EP measurements can be obtained in chronically implanted guinea pigs. Hearing loss after implantation is not explained by changes in strial vascular density or reductions in EP.
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O'Leary SJ, Choi J, Brady K, Matthews S, Ozdowska KB, Payne M, McLean T, Rousset A, Lo J, Creber N, Tari S, Dowell R, Briggs R. Systemic methylprednisolone for hearing preservation during cochlear implant surgery: A double blinded placebo-controlled trial. Hear Res 2021; 404:108224. [PMID: 33774594 DOI: 10.1016/j.heares.2021.108224] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 02/18/2021] [Accepted: 02/22/2021] [Indexed: 01/13/2023]
Abstract
AIM To assess whether a single, peri-operative, high dose of methylprednisolone can improve the preservation of residual acoustic hearing following cochlear implantation (CI). METHODS This was a double blinded placebo-controlled trial, performed in a tertiary academic centre. The hypothesis was that methylprednisolone would improve the preservation of hearing, and lower electrode impedances. Adult patients (18-85 years) with hearing at 85 dB or better at 500 Hz in the ear to be implanted were randomly allocated to either treatment (methylprednisolone, 1g administered intravenously upon induction of anaesthesia) or control (normal saline infusion). As per standard clinical practice, all patients received a routine dose of dexamethasone (8 mg intravenously) on induction of anaesthesia. Implantation was undertaken with a slim and flexible lateral wall electrode via the round window. Surgical technique was routine, with adherence to soft surgical principles. The primary outcome was hearing preservation within 20 dB at 500 Hz, 12 months following cochlear implantation. Secondary outcomes included hearing preservation at 6 weeks and 3 months, monopolar electrode impedance, and Consonant-Vowel-Consonant (CVC) Phoneme scores at 3 and 12 months after surgery. RESULTS Forty-five patients were enrolled into the control group and 48 patients received the steroid. The number of patients achieving hearing preservation at 12 months did not differ significantly between those receiving methylprednisolone treatment and the controls. There were no differences in hearing preservation at any frequency at either 6 weeks or 3 months after implantation. Neither CVC phoneme scores nor electrode impedances differed between the groups. CONCLUSIONS This paper demonstrates that high-dose local steroid injection at surgery was not effective in preventing a loss of residual hearing, improving speech perception, or lowering electrode impedances. The findings were contrary to the experimental literature, and emerging clinical evidence that steroid elution from implant electrodes influences cochlear biology in humans. We found no evidence to support the widely-held practice of administering intravenous steroids in the perioperative period, in an attempt to preserve residual hearing.
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Affiliation(s)
- Stephen J O'Leary
- Department of Surgery - Otolaryngology, The University of Melbourne, Royal Victorian Eye and Ear Hospital, 32 Gisborne St RVEEH, Melbourne East 3002,Victoria, Australia; Cochlear Implant Clinic, Royal Victorian Eye and Ear Hospital, 32 Gisborne St, Melbourne East 3002, Australia.
| | - June Choi
- Department of Surgery - Otolaryngology, The University of Melbourne, Royal Victorian Eye and Ear Hospital, 32 Gisborne St RVEEH, Melbourne East 3002,Victoria, Australia; Department of Otorhinolaryngology - Head & Neck Surgery, Ansan Hospital, College of Medicine, Korea University, 123, Jeokgeum-ro (Street), Gojan-dong, Danwon-gu, Ansan-si, Gyeonggi-do 15355, Republic of Korea
| | - Karina Brady
- Department of Surgery - Otolaryngology, The University of Melbourne, Royal Victorian Eye and Ear Hospital, 32 Gisborne St RVEEH, Melbourne East 3002,Victoria, Australia
| | - Sheila Matthews
- Department of Surgery - Otolaryngology, The University of Melbourne, Royal Victorian Eye and Ear Hospital, 32 Gisborne St RVEEH, Melbourne East 3002,Victoria, Australia
| | - Katie Boncza Ozdowska
- Department of Surgery - Otolaryngology, The University of Melbourne, Royal Victorian Eye and Ear Hospital, 32 Gisborne St RVEEH, Melbourne East 3002,Victoria, Australia
| | - Matthew Payne
- Department of Surgery - Otolaryngology, The University of Melbourne, Royal Victorian Eye and Ear Hospital, 32 Gisborne St RVEEH, Melbourne East 3002,Victoria, Australia
| | - Tim McLean
- Department of Surgery - Otolaryngology, The University of Melbourne, Royal Victorian Eye and Ear Hospital, 32 Gisborne St RVEEH, Melbourne East 3002,Victoria, Australia
| | - Alex Rousset
- Department of Surgery - Otolaryngology, The University of Melbourne, Royal Victorian Eye and Ear Hospital, 32 Gisborne St RVEEH, Melbourne East 3002,Victoria, Australia
| | - Jonathon Lo
- Department of Surgery - Otolaryngology, The University of Melbourne, Royal Victorian Eye and Ear Hospital, 32 Gisborne St RVEEH, Melbourne East 3002,Victoria, Australia
| | - Nathan Creber
- Department of Surgery - Otolaryngology, The University of Melbourne, Royal Victorian Eye and Ear Hospital, 32 Gisborne St RVEEH, Melbourne East 3002,Victoria, Australia
| | - Sylvia Tari
- Department of Surgery - Otolaryngology, The University of Melbourne, Royal Victorian Eye and Ear Hospital, 32 Gisborne St RVEEH, Melbourne East 3002,Victoria, Australia
| | - Richard Dowell
- Department of Surgery - Otolaryngology, The University of Melbourne, Royal Victorian Eye and Ear Hospital, 32 Gisborne St RVEEH, Melbourne East 3002,Victoria, Australia; Department of Audiology and Speech Sciences, University of Melbourne, 550 Swanston St, Carlton 3053, Australia
| | - Robert Briggs
- Department of Surgery - Otolaryngology, The University of Melbourne, Royal Victorian Eye and Ear Hospital, 32 Gisborne St RVEEH, Melbourne East 3002,Victoria, Australia; Cochlear Implant Clinic, Royal Victorian Eye and Ear Hospital, 32 Gisborne St, Melbourne East 3002, Australia
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Tejani VD, Kim JS, Oleson JJ, Abbas PJ, Brown CJ, Hansen MR, Gantz BJ. Residual Hair Cell Responses in Electric-Acoustic Stimulation Cochlear Implant Users with Complete Loss of Acoustic Hearing After Implantation. J Assoc Res Otolaryngol 2021; 22:161-176. [PMID: 33538936 DOI: 10.1007/s10162-021-00785-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 01/03/2021] [Indexed: 11/27/2022] Open
Abstract
Changes in cochlear implant (CI) design and surgical techniques have enabled the preservation of residual acoustic hearing in the implanted ear. While most Nucleus Hybrid L24 CI users retain significant acoustic hearing years after surgery, 6-17 % experience a complete loss of acoustic hearing (Roland et al. Laryngoscope. 126(1):175-81. (2016), Laryngoscope. 128(8):1939-1945 (2018); Scheperle et al. Hear Res. 350:45-57 (2017)). Electrocochleography (ECoG) enables non-invasive monitoring of peripheral auditory function and may provide insight into the pathophysiology of hearing loss. The ECoG response is evoked using an acoustic stimulus and includes contributions from the hair cells (cochlear microphonic-CM) as well as the auditory nerve (auditory nerve neurophonic-ANN). Seven Hybrid L24 CI users with complete loss of residual hearing months after surgery underwent ECoG measures before and after loss of hearing. While significant reductions in CMs were evident after hearing loss, all participants had measurable CMs despite having no measurable acoustic hearing. None retained measurable ANNs. Given histological data suggesting stable hair cell and neural counts after hearing loss (e.g., Quesnel et al. Hear Res. 333:225-234. (2016)), the loss of ECoG and audiometric hearing may reflect reduced synaptic input. This is consistent with the theory that residual CM responses coupled with little to no ANN responses reflect a "disconnect" between hair cells and auditory nerve fibers (Fontenot et al. Ear Hear. 40(3):577-591. 2019). This "disconnection" may prevent proper encoding of auditory stimulation at higher auditory pathways, leading to a lack of audiometric responses, even in the presence of viable cochlear hair cells.
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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.
| | - 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
| | - Jacob J Oleson
- Department of Biostatistics, University of Iowa, 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
| | - 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
| | - 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
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41
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Shen N, Zhou L, Lai B, Li S. The Influence of Cochlear Implant-Based Electric Stimulation on the Electrophysiological Characteristics of Cultured Spiral Ganglion Neurons. Neural Plast 2020; 2020:3108490. [PMID: 32963515 PMCID: PMC7490630 DOI: 10.1155/2020/3108490] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 07/22/2020] [Accepted: 08/17/2020] [Indexed: 11/17/2022] Open
Abstract
Background Cochlear implant-based electrical stimulation may be an important reason to induce the residual hearing loss after cochlear implantation. In our previous study, we found that charge-balanced biphasic electrical stimulation inhibited the neurite growth of spiral ganglion neurons (SGNs) and decreased Schwann cell density in vitro. In this study, we want to know whether cochlear implant-based electrical stimulation can induce the change of electrical activity in cultured SGNs. Methods Spiral ganglion neuron electrical stimulation in vitro model is established using the devices delivering cochlear implant-based electrical stimulation. After 48 h treatment by 50 μA or 100 μA electrical stimulation, the action potential (AP) and voltage depended calcium current (I Ca) of SGNs are recorded using whole-cell electrophysiological method. Results The results show that the I Ca of SGNs is decreased significantly in 50 μA and 100 μA electrical stimulation groups. The reversal potential of I Ca is nearly +80 mV in control SGN, but the reversal potential decreases to +50 mV in 50 μA and 100 μA electrical stimulation groups. Interestingly, the AP amplitude, the AP latency, and the AP duration of SGNs have no statistically significant differences in all three groups. Conclusion Our study suggests cochlear implant-based electrical stimulation only significantly inhibit the I Ca of cultured SGNs but has no effect on the firing of AP, and the relation of I Ca inhibition and SGN damage induced by electrical stimulation and its mechanism needs to be further studied.
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Affiliation(s)
- Na Shen
- Department of Otolaryngology, Zhongshan Hospital, Fudan University, Shanghai, China
- ENT Institute and Department of Otolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China
| | - Lei Zhou
- Department of Otolaryngology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Bin Lai
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Shufeng Li
- ENT Institute and Department of Otolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, China
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Na G, Lee JM, Lee HJ, Jeong Y, Jung J, Choi JY. Effect of Cochlear Implantation on Hearing Fluctuation in Patients with Biallelic SLC26A4 Variants. Audiol Neurootol 2020; 26:111-120. [PMID: 32877901 DOI: 10.1159/000508858] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 05/21/2020] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION Fluctuating hearing loss is a distinctive feature caused by SLC26A4 variants. We investigated whether cochlear implantation had protective or deleterious effect on hearing fluctuation in patients with biallelic SLC26A4 variants. METHODS Patients with biallelic SLC26A4 variants (N = 16; age = 10.24 ± 9.20 years) who had unilateral cochlear implantation and consecutive postsurgical, bilateral pure-tone audiograms more than 3 times were selected. We retrospectively reviewed the patients' medical records from 2008 to 2019 obtained from a tertiary medical center and used the auditory threshold change (Shift) over time as a marker of hearing fluctuation. Fluctuation events were counted, and the Shift of the implanted and contralateral ears was compared using logistic regression with a generalized estimating equation and linear mixed model. A total of 178 values were included. RESULTS The odds of fluctuating hearing frequency were 11.185-fold higher in the unimplanted ears than in the implanted ears postoperatively (p = 0.001). The extent of fluctuation at 250 and 500 Hz was also significantly lower in the implanted ears than in the unimplanted ears after adjusting for every other effect (p = 0.003 and p < 0.001, respectively). Notably, higher residual hearing was rather associated with lesser fluctuation in frequency and the extent of fluctuation at 500 Hz, indicating residual hearing function is not the positive predictor for hearing fluctuation. CONCLUSION In patients with biallelic SLC26A4 variants, cochlear implantation may reduce the frequency and extent of hearing fluctuations.
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Affiliation(s)
- Gina Na
- Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jeon Mi Lee
- Department of Otorhinolaryngology, Ilsan Paik Hospital, Inje University College of Medicine, Goyang, Republic of Korea
| | - Hyun Jin Lee
- Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Republic of Korea.,Department of Otorhinolaryngology-Head and Neck Surgery, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Yeonsu Jeong
- Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jinsei Jung
- Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Republic of Korea,
| | - Jae Young Choi
- Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Republic of Korea
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Swiderski DL, Colesa DJ, Hughes AP, Raphael Y, Pfingst BE. Relationships between Intrascalar Tissue, Neuron Survival, and Cochlear Implant Function. J Assoc Res Otolaryngol 2020; 21:337-352. [PMID: 32691251 PMCID: PMC7445211 DOI: 10.1007/s10162-020-00761-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 07/12/2020] [Indexed: 12/15/2022] Open
Abstract
Fibrous tissue and/or new bone are often found surrounding a cochlear implant in the cochlear scalae. This new intrascalar tissue could potentially limit cochlear implant function by increasing impedance and altering signaling pathways between the implant and the auditory nerve. In this study, we investigated the relationship between intrascalar tissue and 5 measures of implant function in guinea pigs. Variation in both spiral ganglion neuron (SGN) survival and intrascalar tissue was produced by implanting hearing ears, ears deafened with neomycin, and neomycin-deafened ears treated with a neurotrophin. We found significant effects of SGN density on 4 functional measures but adding intrascalar tissue level to the analysis did not explain more variation in any measure than was explained by SGN density alone. These results suggest that effects of intrascalar tissue on electrical hearing are relatively unimportant in comparison to degeneration of the auditory nerve, although additional studies in human implant recipients are still needed to assess the effects of this tissue on complex hearing tasks like speech perception. The results also suggest that efforts to minimize the trauma that aggravates both tissue development and SGN loss could be beneficial.
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Affiliation(s)
- Donald L Swiderski
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Deborah J Colesa
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Aaron P Hughes
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Yehoash Raphael
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Bryan E Pfingst
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA.
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Abstract
OBJECTIVES To assess the effect on impedance levels of intraoperative reinsertion of a cochlear implant (CI) array compared with matched controls. STUDY DESIGN Retrospective patient review. SETTING Cochlear implant center. PATIENTS CI recipients in the Sydney Cochlear Implant Centre (SCIC) database who required intraoperative array reinsertion and matched controls. Exclusion criteria; known preceding meningitis or labyrinthitis ossificans; electrode array buckling; incomplete "final" insertion. INTERVENTION Cochlear implantation. MAIN OUTCOME MEASURES Impedance values measured intraoperatively, at switch on, 3 months, 6 months, and 12 months postoperatively were analyzed. The Generalized Estimating Equation (GEE) Model was used to compare cases with controls for each device, at each time point, and for each channel. RESULTS Thirty-one reinsertion cases identified; six CI 422 arrays; 14 CI 24RE (ST) arrays, and 11 CI 512 arrays. No increase in impedance levels was found in the reinsertion cases when compared with their matched controls. The only statistical difference in impedance was seen in the CI 422 cohort at switch on with the reinsertion cases having lower impedances (p = 0.03). CONCLUSION This is the first study to examine impedance values in patients who underwent intraoperative CI array reinsertion and to compare them with the impedances of matched controls. No significant increase found in impedances between our reinsertion cases and matched controls, suggesting the reinsertion did not result in any additional trauma or inflammation. This has implications for surgery both in routine cases such as a faulty electrode and also for future design of mechanisms for delivery of intracochlear therapies.
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Recent advances in the implant-based drug delivery in otorhinolaryngology. Acta Biomater 2020; 108:46-55. [PMID: 32289495 DOI: 10.1016/j.actbio.2020.04.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/31/2020] [Accepted: 04/03/2020] [Indexed: 12/13/2022]
Abstract
The surgical implant is an interdisciplinary therapeutic modality that offers unique advantages in the daily practice of otorhinolaryngology. Some well-known examples include cochlear implants, bone-anchored hearing aids, sinus stents, and tracheostomy tubes. Neuroprotective, osteogenic, anti-inflammatory, and antimicrobial effects are among their established or pursued functions. Implant-based drug delivery affords an efficient and potent approach to enhancing these therapeutic functions. Recent innovations have infiltrated all four elements of a drug-eluting implant. The purpose of this pre-clinical, biotechnology-oriented review is to discuss these developments in terms of the implant biomaterial, loaded medication, delivery pattern, and system fabrication. Cell-mediated neurotrophin release, fabrication of a hydroxyapatite-supported system, biodegradable polymer-based implants, and multiclass and multidrug delivery are some representative advancements. The ultimate goal here is to bridge the gap between biotechnology advances and clinical needs. The review is concluded with a perspective regarding the future opportunities and challenges in this popular and rapidly developing subject of research. STATEMENT OF SIGNIFICANCE: Surgical implants and local drug delivery are representative modern modalities of surgical treatment and medical treatment, respectively. Their synergy offers unique therapeutic advantages, such as minimal systemic side effects, proximity-related high efficiency, and potential absorbability. The applications of implant-based drug delivery have infiltrated otorhinolaryngology and head & neck surgery, which is well known for its related tissue diversity and surgical complexity. Examples discussed here include cochlear implants, bone-anchored hearing aids, sinus stents, and airway tubes. This timely review focuses primarily on the four fundamental components of an implant-based drug delivery system, namely implant biomaterial, loaded medication, delivery pattern, and system fabrication. A particular emphasis is placed upon the in vitro cellular and in vivo animal studies that demonstrate pre-clinical potentials.
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Comparison of electrode impedance measures between a dexamethasone-eluting and standard Cochlear™ Contour Advance® electrode in adult cochlear implant recipients. Hear Res 2020; 390:107924. [DOI: 10.1016/j.heares.2020.107924] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 02/10/2020] [Accepted: 02/13/2020] [Indexed: 11/22/2022]
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In Vivo Real-time Remote Cochlear Implant Capacitive Impedance Measurements: A Glimpse Into the Implanted Inner Ear. Otol Neurotol 2020; 40:S18-S22. [PMID: 31225818 DOI: 10.1097/mao.0000000000002214] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVES To propose a remote, real-time, safe, and easy systematic method to determine electrode electric impedance components: access resistance, polarization capacitance, and polarization resistance. PATIENTS Patients who received a cochlear implant and had normal cochlear anatomy and complete array insertion were recruited. A total of four adult patients were included and separated in two groups according to implantation time. INTERVENTION Cochlear implant electrical impedance and its components were measured in all patients by using a novel diagnostic tool: a custom made software running in the patient's computer. Data is transmitted in real time to the investigator. Various stimulation and measuring strategies were used to obtain specific information in each cochlear region. MAIN OUTCOME MEASURES Access resistance, polarization capacitance, and resistance of each patient were measured. Measurement success rate and required time for the patient were recorded. RESULTS Access resistance, polarization capacitance, and resistance were obtained in different modes, thus in every specific region of the cochlea. All measurements were successful. Each measurement took approximately 7 minutes and was transmitted in real time to the investigators. CONCLUSION Routine use of this tool may allow constant assessment of cochlear health and could be eventually used to monitor the effect of drugs in the inner ear. This methodology provides an in vivo "electrical view" of the inside of the implanted cochlea.
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Choong JK, Hampson AJ, Brody KM, Lo J, Bester CW, Gummer AW, Reynolds NP, O'Leary SJ. Nanomechanical mapping reveals localized stiffening of the basilar membrane after cochlear implantation. Hear Res 2019; 385:107846. [PMID: 31786442 DOI: 10.1016/j.heares.2019.107846] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 11/02/2019] [Accepted: 11/10/2019] [Indexed: 01/12/2023]
Abstract
Cochlear implantation leads to many structural changes within the cochlea which can impair residual hearing. In patients with preserved low-frequency hearing, a delayed hearing loss can occur weeks-to-years post-implantation. We explore whether stiffening of the basilar membrane (BM) may be a contributory factor in an animal model. Our objective is to map changes in morphology and Young's modulus of basal and apical areas of the BM after cochlear implantation, using quantitative nanomechanical atomic force microscopy (QNM-AFM) after cochlear implant surgery. Cochlear implantation was undertaken in the guinea pig, and the BM was harvested at four time-points: 1 day, 14 days, 28 days and 84 days post-implantation for QNM-AFM analysis. Auditory brainstem response thresholds were determined prior to implantation and termination. BM tissue showed altered morphology and a progressive increase in Young's modulus, mainly in the apex, over time after implantation. BM tissue from the cochlear base demonstrated areas of extreme stiffness which are likely due to micro-calcification on the BM. In conclusion, stiffening of the BM after cochlear implantation occurs over time, even at sites far apical to a cochlear implant.
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Affiliation(s)
- Jessica K Choong
- Otolaryngology, Department of Surgery, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Amy J Hampson
- Otolaryngology, Department of Surgery, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Kate M Brody
- Otolaryngology, Department of Surgery, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Jonathon Lo
- Otolaryngology, Department of Surgery, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Christofer W Bester
- Otolaryngology, Department of Surgery, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Anthony W Gummer
- Section of Physiological Acoustics and Communication, Department of Otolaryngology, Eberhard-Karls-University Tübingen, Elfriede-Aulhorn-Strasse 5, 72076, Tübingen, Germany
| | - Nicholas P Reynolds
- ARC Training Centre for Biodevices, Swinburne University of Technology, Hawthorn, Australia; Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Australia.
| | - Stephen J O'Leary
- Otolaryngology, Department of Surgery, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia.
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Foggia MJ, Quevedo RV, Hansen MR. Intracochlear fibrosis and the foreign body response to cochlear implant biomaterials. Laryngoscope Investig Otolaryngol 2019; 4:678-683. [PMID: 31890888 PMCID: PMC6929576 DOI: 10.1002/lio2.329] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 10/30/2019] [Indexed: 12/31/2022] Open
Abstract
OBJECTIVE To report current knowledge on the topic of intracochlear fibrosis and the foreign body response following cochlear implantation (CI). METHODS A literature search was performed in PubMed to identify peer-reviewed articles. Search components included "cochlear implant," "Foreign body response (FBR)," and "fibrosis." Original studies and review articles relevant to the topic were included. RESULTS Ninety peer-reviewed articles describing the foreign body response or intracochlear fibrosis following CI were included. CONCLUSIONS Intracochlear fibrosis following CI represents a significant limiting factor for the success of CI users. Several strategies have been employed to mitigate the foreign body response within the cochlea including drug delivery systems and modifications in surgical technique and electrode design. A better understanding of the FBR has the potential to improve CI outcomes and the next generation of cochlear prostheses.
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Affiliation(s)
- Megan J. Foggia
- Department of Otolaryngology—Head & Neck SurgeryUniversity of Iowa Hospitals and ClinicsIowa CityIowa
| | - Rene Vielman Quevedo
- Department of Otolaryngology—Head & Neck SurgeryUniversity of Iowa Hospitals and ClinicsIowa CityIowa
| | - Marlan R. Hansen
- Department of Otolaryngology—Head & Neck SurgeryUniversity of Iowa Hospitals and ClinicsIowa CityIowa
- Department of NeurosurgeryUniversity of Iowa Hospitals and ClinicsIowa CityIowa
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50
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Liang Q, Shen N, Lai B, Xu C, Sun Z, Wang Z, Li S. Electrical Stimulation Degenerated Cochlear Synapses Through Oxidative Stress in Neonatal Cochlear Explants. Front Neurosci 2019; 13:1073. [PMID: 31680814 PMCID: PMC6803620 DOI: 10.3389/fnins.2019.01073] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 09/24/2019] [Indexed: 11/30/2022] Open
Abstract
Neurostimulation devices use electrical stimulation (ES) to substitute, supplement or modulate neural function. However, the impact of ES on their modulating structures is largely unknown. For example, recipients of cochlear implants using electroacoustic stimulation experienced delayed loss of residual hearing over time after ES, even though ES had no impact on the morphology of hair cells. In this study, using a novel model of cochlear explant culture with charge-balanced biphasic ES, we found that ES did not change the quantity and morphology of hair cells but decreased the number of inner hair cell (IHC) synapses and the density of spiral ganglion neuron (SGN) peripheral fibers. Inhibiting calcium influx with voltage-dependent calcium channel (VDCC) blockers attenuated the loss of SGN peripheral fibers and IHC synapses induced by ES. ES increased ROS/RNS in cochlear explants, but the inhibition of calcium influx abolished this effect. Glutathione peroxidase 1 (GPx1) and GPx2 in cochlear explants decreased under ES and ebselen abolished this effect and attenuated the loss of SGN peripheral fibers. This finding demonstrated that ES induced the degeneration of SGN peripheral fibers and IHC synapses in a current intensity- and duration-dependent manner in vitro. Calcium influx resulting in oxidative stress played an important role in this process. Additionally, ebselen might be a potential protector of ES-induced cochlear synaptic degeneration.
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Affiliation(s)
- Qiong Liang
- Department of Otolaryngology, Eye and ENT Hospital of Fudan University, Shanghai, China.,National Health Commission Key Laboratory of Hearing Medicine, Shanghai, China
| | - Na Shen
- Department of Otolaryngology, Eye and ENT Hospital of Fudan University, Shanghai, China.,National Health Commission Key Laboratory of Hearing Medicine, Shanghai, China.,Department of Otolaryngology, Zhongshan Hospital of Fudan University, Shanghai, China
| | - Bin Lai
- State Key Laboratory of Medical Neurobiology, Shanghai, China
| | - Changjian Xu
- Shanghai Cochlear Engineering Technology Research Center, Shanghai, China
| | - Zengjun Sun
- Shanghai Cochlear Engineering Technology Research Center, Shanghai, China
| | - Zhengmin Wang
- Department of Otolaryngology, Eye and ENT Hospital of Fudan University, Shanghai, China.,National Health Commission Key Laboratory of Hearing Medicine, Shanghai, China
| | - Shufeng Li
- Department of Otolaryngology, Eye and ENT Hospital of Fudan University, Shanghai, China.,National Health Commission Key Laboratory of Hearing Medicine, Shanghai, China
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