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Mushtaq F, Soulby A, Boyle P, Papoutselou E, Nunn T, Hartley DEH. Self-Assessment of Cochlear Health by New Cochlear Implant Recipients: Daily Impedance, Electrically Evoked Compound Action Potential and Electrocochleography Measurements Over the First Three Postoperative Months. Otol Neurotol 2024:00129492-990000000-00564. [PMID: 38918070 DOI: 10.1097/mao.0000000000004227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2024]
Abstract
HYPOTHESES In newly implanted cochlear implant (CI) users, electrically evoked compound action (eCAPs) and electrocochleography (ECochGs) will remain stable over time. Electrode impedances will increase immediately postimplantation due to the initial inflammatory response, before decreasing after CI switch-on and stabilizing thereafter. BACKGROUND The study of cochlear health (CH) has several applications, including explaining variation in CI outcomes, informing CI programming strategies, and evaluating the safety and efficacy of novel biological treatments for hearing loss. Very early postoperative CH patterns have not previously been intensively explored through longitudinal daily testing. Thanks to technological advances, electrode impedances, eCAPs, and ECochGs can be independently performed by CI users at home to monitor CH over time. METHODS A group of newly implanted CI users performed daily impedances, eCAPs, and ECochGs for 3 months at home, starting from the first day postsurgery (N = 7) using the Active Insertion Monitoring system by Advanced Bionics. RESULTS Measurement validity of 93.5, 93.0, and 81.6% for impedances, eCAPs, and ECochGs, respectively, revealed high participant compliance. Impedances increased postsurgery before dropping and stabilizing after switch-on. eCAPs showed good stability, though statistical analyses revealed a very small but significant increase in thresholds over time. Most ECochG thresholds did not reach the liberal signal-to-noise criterion of 2:1, with low threshold stability over time. CONCLUSION Newly implanted CI recipients can confidently and successfully perform CH recordings at home, highlighting the valuable role of patients in longitudinal data collection. Electrode impedances and eCAPs are promising objective measurements for evaluating CH in newly implanted CI users.
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Affiliation(s)
| | - Andrew Soulby
- St. Thomas' Hearing Implant Centre, St. Thomas' Hospital, London, United Kingdom
| | - Patrick Boyle
- Advanced Bionics GmbH, European Research Center, Hannover, Germany
| | | | - Terry Nunn
- St. Thomas' Hearing Implant Centre, St. Thomas' Hospital, London, United Kingdom
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Alahmadi A, Abdelsamad Y, Yousef M, Almuhawas F, Hafez A, Alzhrani F, Hagr A. Cochlear Implantation: Long-Term Effect of Early Activation on Electrode Impedance. J Clin Med 2024; 13:3299. [PMID: 38893010 PMCID: PMC11172931 DOI: 10.3390/jcm13113299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2024] [Revised: 05/17/2024] [Accepted: 05/24/2024] [Indexed: 06/21/2024] Open
Abstract
Objectives: The growing adoption of cochlear implants (CIs) necessitates understanding the factors influencing long-term performance and improved outcomes. This work investigated the long-term effect of early activation of CIs on electrode impedance in a large sample of CI users at different time points. Methods: A retrospective study on 915 ears from CI patients who were implanted between 2015 and 2020. According to their CI audio processor activation time, the patients were categorized into early activation (activated 1 day after surgery, n = 481) and classical activation (activated 4 weeks after surgery, n = 434) groups. Then, the impact of the activation times on the electrode impedance values, along the electrode array contacts, at different time points up to two years was studied and analyzed. Results: The early activation group demonstrated lower impedance values across all the electrode array sections compared to the classical activation at 1 month, 1 year, and 2 years post-implantation. At 1 month, early activation was associated with a reduction of 0.34 kΩ, 0.46 kΩ, and 0.37 kΩ in the apical, middle, and basal sections, respectively. These differences persisted at subsequent intervals. Conclusions: Early activation leads to sustained reductions in the electrode impedance compared to classical activation (CA), suggesting that earlier activation might positively affect long-term CI outcomes.
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Affiliation(s)
- Asma Alahmadi
- King Abdullah Ear Specialist Center (KAESC), King Saud Medical City, King Saud University, Riyadh 11411, Saudi Arabia; (M.Y.); (F.A.); (F.A.); (A.H.)
| | - Yassin Abdelsamad
- Research Department, MED-EL GmbH, Riyadh 11563, Saudi Arabia; (Y.A.); (A.H.)
| | - Medhat Yousef
- King Abdullah Ear Specialist Center (KAESC), King Saud Medical City, King Saud University, Riyadh 11411, Saudi Arabia; (M.Y.); (F.A.); (F.A.); (A.H.)
- Audio Vestibular Unit, ENT Department, Menoufia University, Menoufia 32928, Egypt
| | - Fida Almuhawas
- King Abdullah Ear Specialist Center (KAESC), King Saud Medical City, King Saud University, Riyadh 11411, Saudi Arabia; (M.Y.); (F.A.); (F.A.); (A.H.)
| | - Ahmed Hafez
- Research Department, MED-EL GmbH, Riyadh 11563, Saudi Arabia; (Y.A.); (A.H.)
| | - Farid Alzhrani
- King Abdullah Ear Specialist Center (KAESC), King Saud Medical City, King Saud University, Riyadh 11411, Saudi Arabia; (M.Y.); (F.A.); (F.A.); (A.H.)
| | - Abdulrahman Hagr
- King Abdullah Ear Specialist Center (KAESC), King Saud Medical City, King Saud University, Riyadh 11411, Saudi Arabia; (M.Y.); (F.A.); (F.A.); (A.H.)
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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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Yancey KL, Patro A, Smetak M, Perkins EL, Isaacson B, Bennett ML, O'Malley M, Haynes DS, Hunter JB. Evaluating calcium channel blockers and bisphosphonates as otoprotective agents in cochlear implantation hearing preservation candidates. Cochlear Implants Int 2024:1-9. [PMID: 38738388 DOI: 10.1080/14670100.2024.2338003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2024]
Abstract
OBJECTIVES Evaluate potential effects of calcium channel blockers (CCB) and bisphosphonates (BP) on residual hearing following cochlear implantation. METHODS Medications of 303 adult hearing preservation (HP) candidates (low frequency pure tone average [LFPTA] of 125, 250, and 500 Hz ≤80 dB HL) were reviewed. Postimplantation LFPTA of patients taking CCBs and BPs were compared to controls matched by age and preimplantation LFPTA. RESULTS Twenty-six HP candidates were taking a CCB (N = 14) or bisphosphonate (N = 12) at implantation. Median follow-up was 1.37 years (range 0.22-4.64y). Among subjects with initial HP, 29% (N = 2 of 7) CCB users compared to 50% (N = 2 of 4) controls subsequently lost residual hearing 3-6 months later (OR = 0.40, 95% CI = 0.04-4.32, p = 0.58). None of the four BP patients with initial HP experienced delayed loss compared to 50% (N = 2 of 4) controls with initial HP (OR = 0.00, 95% CI = 0.00-1.95, P = 0.43). Two CCB and one BP patients improved to a LFPTA <80 dB HL following initial unaided thresholds that suggested loss of residual hearing. DISCUSSION There were no significant differences in the odds of delayed loss of residual hearing with CCBs or BPs. CONCLUSION Further investigation into potential otoprotective adjuvants for maintaining residual hearing following initial successful hearing preservation is warranted, with larger cohorts and additional CCB/BP agents.
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Affiliation(s)
- Kristen L Yancey
- Department of Otolaryngology-Head and Neck Surgery, Weill Cornell Medical Center/New York Presbyterian Hospital, New York, NY, USA
| | - Ankita Patro
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Miriam Smetak
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Elizabeth L Perkins
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Brandon Isaacson
- Department of Otolaryngology-Head and Neck Surgery, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Marc L Bennett
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Matthew O'Malley
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - David S Haynes
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jacob B Hunter
- Department of Otolaryngology-Head and Neck Surgery, Thomas Jefferson University Hospital, Philadelphia, PA, USA
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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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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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Hu M, Liang C, Wang D. Implantable bioelectrodes: challenges, strategies, and future directions. Biomater Sci 2024; 12:270-287. [PMID: 38175154 DOI: 10.1039/d3bm01204b] [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: 01/05/2024]
Abstract
Implantable bioelectrodes for regulating and monitoring biological behaviors have become indispensable medical devices in modern healthcare, alleviating pathological symptoms such as epilepsy and arrhythmia, and assisting in reversing conditions such as deafness and blindness. In recent years, developments in the fields of materials science and biomedical engineering have contributed to advances in research on implantable bioelectrodes. However, the foreign body reaction (FBR) is still a major constraint for the long-term application of electrodes. In this paper, four types of commonly used implantable bioelectrodes are reviewed, concentrating on their background, development, and a series of complications caused by FBR after long-term implantation. Strategies for resisting FBRs are then devised in terms of physics, chemistry, and nanotechnology. We analyze the major trends in the future development of implantable bioelectrodes and outline some promising research to optimize the long-term operational stability of electrodes. Although current implantable bioelectrodes have been able to achieve good biocompatibility, low impedance, and low mechanical mismatch and trauma, these devices still face the challenge of FBR. Resistance to FBR is still the key for the long-term effectiveness of bioelectrodes, and a better understanding of the mechanisms of FBR, as well as miniaturization, long-term passivation, and coupling with gene therapy may be the way forward for the next generation of implantable bioelectrodes.
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Affiliation(s)
- Mengyuan Hu
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
| | - Chunyong Liang
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
| | - Donghui Wang
- Hebei Key Laboratory of Biomaterials and Smart Theranostics, School of Health Sciences and Biomedical Engineering, Hebei University of Technology, Tianjin 300130, China.
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Micaletti F, Escoffre JM, Kerneis S, Bouakaz A, Galvin JJ, Boullaud L, Bakhos D. Microbubble-assisted ultrasound for inner ear drug delivery. Adv Drug Deliv Rev 2024; 204:115145. [PMID: 38042259 DOI: 10.1016/j.addr.2023.115145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 11/20/2023] [Accepted: 11/22/2023] [Indexed: 12/04/2023]
Abstract
Treating pathologies of the inner ear is a major challenge. To date, a wide range of procedures exists for administering therapeutic agents to the inner ear, with varying degrees of success. The key is to deliver therapeutics in a way that is minimally invasive, effective, long-lasting, and without adverse effects on vestibular and cochlear function. Microbubble-assisted ultrasound ("sonoporation") is a promising new modality that can be adapted to the inner ear. Combining ultrasound technology with microbubbles in the middle ear can increase the permeability of the round window, enabling therapeutic agents to be delivered safely and effectively to the inner ear in a targeted manner. As such, sonoporation is a promising new approach to treat hearing loss and vertigo. This review summarizes all studies on the delivery of therapeutic molecules to the inner ear using sonoporation.
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Affiliation(s)
- Fabrice Micaletti
- ENT and Cervico-Facial Surgery Department, University Hospital Center of Tours, 2 Boulevard Tonnellé, 37044 Tours, France.
| | | | - Sandrine Kerneis
- ENT and Cervico-Facial Surgery Department, University Hospital Center of Tours, 2 Boulevard Tonnellé, 37044 Tours, France
| | - Ayache Bouakaz
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France
| | - John J Galvin
- Faculty of medicine, Université de Tours, 10 boulevard Tonnellé, 37044 Tours, France; House Institute Foundation, 2100 W 3rd Street, Suite 111, Los Angeles, CA 90057, USA
| | - Luc Boullaud
- ENT and Cervico-Facial Surgery Department, University Hospital Center of Tours, 2 Boulevard Tonnellé, 37044 Tours, France
| | - David Bakhos
- ENT and Cervico-Facial Surgery Department, University Hospital Center of Tours, 2 Boulevard Tonnellé, 37044 Tours, France; UMR 1253, iBrain, Université de Tours, Inserm, Tours, France; Faculty of medicine, Université de Tours, 10 boulevard Tonnellé, 37044 Tours, France; House Institute Foundation, 2100 W 3rd Street, Suite 111, Los Angeles, CA 90057, USA
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Duan W, Robles UA, Poole-Warren L, Esrafilzadeh D. Bioelectronic Neural Interfaces: Improving Neuromodulation Through Organic Conductive Coatings. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023:e2306275. [PMID: 38115740 DOI: 10.1002/advs.202306275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 11/07/2023] [Indexed: 12/21/2023]
Abstract
Integration of bioelectronic devices in clinical practice is expanding rapidly, focusing on conditions ranging from sensory to neurological and mental health disorders. While platinum (Pt) electrodes in neuromodulation devices such as cochlear implants and deep brain stimulators have shown promising results, challenges still affect their long-term performance. Key among these are electrode and device longevity in vivo, and formation of encapsulating fibrous tissue. To overcome these challenges, organic conductors with unique chemical and physical properties are being explored. They hold great promise as coatings for neural interfaces, offering more rapid regulatory pathways and clinical implementation than standalone bioelectronics. This study provides a comprehensive review of the potential benefits of organic coatings in neuromodulation electrodes and the challenges that limit their effective integration into existing devices. It discusses issues related to metallic electrode use and introduces physical, electrical, and biological properties of organic coatings applied in neuromodulation. Furthermore, previously reported challenges related to organic coating stability, durability, manufacturing, and biocompatibility are thoroughly reviewed and proposed coating adhesion mechanisms are summarized. Understanding organic coating properties, modifications, and current challenges of organic coatings in clinical and industrial settings is expected to provide valuable insights for their future development and integration into organic bioelectronics.
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Affiliation(s)
- Wenlu Duan
- The Graduate School of Biomedical Engineering, UNSW, Sydney, NSW, 2052, Australia
| | | | - Laura Poole-Warren
- The Graduate School of Biomedical Engineering, UNSW, Sydney, NSW, 2052, Australia
- Tyree Foundation Institute of Health Engineering, UNSW, Sydney, NSW, 2052, Australia
| | - Dorna Esrafilzadeh
- The Graduate School of Biomedical Engineering, UNSW, Sydney, NSW, 2052, Australia
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Grzybowski M, Malfeld K, Lenarz T, Scheper V, Schurzig D. Optimization of pharmacological interventions in the guinea pig animal model-a new approach to calculate the perilymph volume of the scala tympani. Front Neurosci 2023; 17:1297046. [PMID: 38161797 PMCID: PMC10754993 DOI: 10.3389/fnins.2023.1297046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 11/29/2023] [Indexed: 01/03/2024] Open
Abstract
Objective The guinea pig serves as a well-established animal model for inner ear research, offering valuable insights into the anatomy, physiology, and therapeutic interventions of the auditory system. However, the heterogeneity of results observed in both in-vivo experiments and clinical studies poses challenges in understanding and optimizing pharmacotherapy outcomes. This heterogeneity may be due to individual differences in the size of the guinea pig cochlea and thus in the volume of the scala tympani (ST), which can lead to different drug concentrations in the ST, a fact that has been largely overlooked thus far. To address this issue, we aimed to develop an approach for calculating the individual volume of perilymph within the ST before and after cochlear implant insertion. Method In this study, high-resolution μCT images of a total of n = 42 guinea pig temporal bones were used to determine the volume of the ST. We compared fresh, frozen, and fixed tissues from both colored and albino strains to evaluate the potential influence of tissue condition and strain on the results. Results Our findings demonstrate a variability in mean ST volume with a relative standard deviation (RSD) of 14.7%, comparable to studies conducted with humans (range RSD: 5 to 20%). This indicates that the guinea pig cochlea exhibits similar variability to that of the human cochlea. Consequently, it is crucial to consider this variability when designing and conducting studies utilizing the guinea pig as an animal model. Furthermore, we successfully developed a tool capable of estimating ST volume without the need for manual segmentation, employing two geometric parameters, basal diameter (A) and width (B) of the cochlea, corresponding to the cochlear footprint. The tool is available for free download and use on our website. Conclusion This novel approach provides researchers with a valuable tool to calculate individual ST volume in guinea pigs, enabling more precise dosing strategies and optimization of drug concentrations for pharmacotherapy studies. Moreover, our study underscores the importance of acknowledging and accounting for inter-individual variability in animal models to enhance the translational relevance and applicability of research outcomes in the field of inner ear investigations.
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Affiliation(s)
- Marleen Grzybowski
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- German Hearing Center Hannover, Hannover Medical School, Hannover, Germany
| | - Kathrin Malfeld
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- Center for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Hannover, Germany
| | - Thomas Lenarz
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- German Hearing Center Hannover, Hannover Medical School, Hannover, Germany
- Center for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Hannover, Germany
| | - Verena Scheper
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- Center for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Hannover, Germany
| | - Daniel Schurzig
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- MED-EL Research Center, Hannover, Germany
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Seicol BJ, Guo Z, Garrity K, Xie R. Potential uses of auditory nerve stimulation to modulate immune responses in the inner ear and auditory brainstem. Front Integr Neurosci 2023; 17:1294525. [PMID: 38162822 PMCID: PMC10755874 DOI: 10.3389/fnint.2023.1294525] [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: 09/14/2023] [Accepted: 12/01/2023] [Indexed: 01/03/2024] Open
Abstract
Bioelectronic medicine uses electrical stimulation of the nervous system to improve health outcomes throughout the body primarily by regulating immune responses. This concept, however, has yet to be applied systematically to the auditory system. There is growing interest in how cochlear damage and associated neuroinflammation may contribute to hearing loss. In conjunction with recent findings, we propose here a new perspective, which could be applied alongside advancing technologies, to use auditory nerve (AN) stimulation to modulate immune responses in hearing health disorders and following surgeries for auditory implants. In this article we will: (1) review the mechanisms of inflammation in the auditory system in relation to various forms of hearing loss, (2) explore nerve stimulation to reduce inflammation throughout the body and how similar neural-immune circuits likely exist in the auditory system (3) summarize current methods for stimulating the auditory system, particularly the AN, and (4) propose future directions to use bioelectronic medicine to ameliorate harmful immune responses in the inner ear and auditory brainstem to treat refractory conditions. We will illustrate how current knowledge from bioelectronic medicine can be applied to AN stimulation to resolve inflammation associated with implantation and disease. Further, we suggest the necessary steps to get discoveries in this emerging field from bench to bedside. Our vision is a future for AN stimulation that includes additional protocols as well as advances in devices to target and engage neural-immune circuitry for therapeutic benefits.
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Affiliation(s)
- Benjamin J. Seicol
- Department of Otolaryngology, The Ohio State University, Columbus, OH, United States
- Department of Neuroscience, The Ohio State University, Columbus, OH, United States
| | - Zixu Guo
- Department of Otolaryngology, The Ohio State University, Columbus, OH, United States
- Department of Neuroscience, The Ohio State University, Columbus, OH, United States
| | - Katy Garrity
- Department of Neuroscience, The Ohio State University, Columbus, OH, United States
| | - Ruili Xie
- Department of Otolaryngology, The Ohio State University, Columbus, OH, United States
- Department of Neuroscience, The Ohio State University, Columbus, OH, United States
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12
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Konrad S, Büchner A, Lenarz T, Paasche G. Impedance development after implantation of hybrid-L24 cochlear implant electrodes. Int J Audiol 2023; 62:1137-1144. [PMID: 36193989 DOI: 10.1080/14992027.2022.2125914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 09/13/2022] [Indexed: 11/05/2022]
Abstract
OBJECTIVE Shorter and thinner electrodes were developed for preserving residual hearing after cochlear implantation by minimising trauma. As trauma is regarded as one of the causes of fibrous tissue formation after implantation, and increase in impedance is considered to be connected to fibrous tissue formation, the aim of the current study was to evaluate impedance development after implantation of Hybrid-L electrodes. DESIGN Impedance values were retrospectively collected from our clinical database and evaluated for all active contacts and basal, middle and apical contacts separately for up to 10 years. STUDY SAMPLES All 137 adult patients received a Hybrid-L electrode and had to be implanted for at least 1 year. RESULTS On average impedances increased to 13 kOhm before first fitting and dropped to 5-7 kOhm under electrical stimulation with lower values measured on apical contacts. Mean values remained stable over years, but variability increased. Values before first fitting were independent of age at implantation whereas lower values were found later in patients of higher age at implantation. CONCLUSION Despite smaller contacts, impedance values after start of electrical stimulation were comparable to published values of Contour electrodes. This might suggest less tissue growth with the Hybrid-L electrode array.
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Affiliation(s)
- Simon Konrad
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Andreas Büchner
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
- Hearing4all Cluster of Excellence, Hannover Medical School, Hannover, Germany
| | - Thomas Lenarz
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
- Hearing4all Cluster of Excellence, Hannover Medical School, Hannover, Germany
| | - Gerrit Paasche
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
- Hearing4all Cluster of Excellence, Hannover Medical School, Hannover, Germany
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13
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Behrends W, Ahrens D, Bankstahl JP, Esser KH, Paasche G, Lenarz T, Scheper V. Refinement of systemic guinea pig deafening in hearing research: Sensorineural hearing loss induced by co-administration of kanamycin and furosemide via the leg veins. Lab Anim 2023; 57:631-641. [PMID: 37070340 DOI: 10.1177/00236772231167679] [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: 04/19/2023]
Abstract
Auditory disabilities have a large impact on the human population worldwide. Research into understanding and treating hearing disabilities has increased significantly in recent years. One of the most relevant animal species in this context is the guinea pig, which has to be deafened to study several of the hearing pathologies and develop novel therapies. Applying kanamycin subcutaneously and furosemide intravenously is a long-established method in hearing research, leading to permanent hearing loss without surgical intervention at the ear. The intravenous application of furosemide requires invasive surgery in the cervical area of the animals to expose the jugular vein, since a relatively large volume (1 ml per 500 g body weight) must be injected over a period of about 2.5 min. We have established a gentler alternative by applying the furosemide by puncture of the leg veins. For this, custom-made cannula-needle devices were built to allow the vein puncture and subsequent slow injection of the furosemide. This approach was tested in 11 guinea pigs through the foreleg via the cephalic antebrachial vein and through the hind leg via the saphenous vein. Frequency-specific hearing thresholds were measured before and after the procedure to verify normal hearing and successful deafening, respectively. The novel approach of systemic deafening was successfully implemented in 10 out of 11 animals. The Vena saphena was best suited to the application. Since the animals' condition, post leg vein application, was better in comparison to animals deafened by exposure of the Vena jugularis, the postulated refinement that reduced animal stress was deemed successful.
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Affiliation(s)
- Wiebke Behrends
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
- Auditory Neuroethology and Neurobiology, Institute of Zoology, University of Veterinary Medicine Hannover Foundation, Germany
| | - Daniel Ahrens
- Department of Nuclear Medicine, Hannover Medical School, Germany
| | - Jens P Bankstahl
- Department of Nuclear Medicine, Hannover Medical School, Germany
| | - Karl-Heinz Esser
- Auditory Neuroethology and Neurobiology, Institute of Zoology, University of Veterinary Medicine Hannover Foundation, Germany
| | - Gerrit Paasche
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
- Hearing4all Cluster of Excellence, Hannover Medical School, Germany
| | - Thomas Lenarz
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
- Hearing4all Cluster of Excellence, Hannover Medical School, Germany
| | - Verena Scheper
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
- Hearing4all Cluster of Excellence, Hannover Medical School, Germany
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14
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Rahman MT, Mostaert BJ, Hunger B, Saha U, Claussen AD, Razu I, Nasrin F, Khan NA, Eckard P, Coleman S, Oleson J, Kirk JR, Hirose K, Hansen MR. Contribution of macrophages to neural survival and intracochlear tissue remodeling responses following cochlear implantation. J Neuroinflammation 2023; 20:266. [PMID: 37974203 PMCID: PMC10652501 DOI: 10.1186/s12974-023-02955-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 11/10/2023] [Indexed: 11/19/2023] Open
Abstract
BACKGROUND Cochlear implants (CIs) restore hearing to deafened patients. The foreign body response (FBR) following cochlear implantation (post-CI) comprises an infiltration of macrophages, other immune and non-immune cells, and fibrosis into the scala tympani, a space that is normally devoid of cells. This FBR is associated with negative effects on CI outcomes including increased electrode impedances and loss of residual acoustic hearing. This study investigates the extent to which macrophage depletion by an orally administered CSF-1R specific kinase (c-FMS) inhibitor, PLX-5622, modulates the tissue response to CI and neural health. MAIN TEXT 10- to 12-week-old CX3CR1 + /GFP Thy1 + /YFP mice on C57BL/6J/B6 background was fed chow containing 1200 mg/kg PLX5622 or control chow for the duration of the study. 7 days after starting the diet, 3-channel cochlear implants were implanted in the ear via the round window. Serial impedance and neural response telemetry (NRT) measurements were acquired throughout the study. Electric stimulation began 7 days post-CI until 28 days post-CI for 5 h/day, 5 days/week, with programming guided by NRT and behavioral responses. Cochleae harvested at 10, 28 or 56 days post-CI were cryosectioned and labeled with an antibody against α-smooth muscle actin (α-SMA) to identify myofibroblasts and quantify the fibrotic response. Using IMARIS image analysis software, the outlines of scala tympani, Rosenthal canal, modiolus, and lateral wall for each turn were traced manually to measure region volume. The density of nuclei, CX3CR1 + macrophages, Thy1 + spiral ganglion neuron (SGN) numbers, and the ratio of the α-SMA + volume/scala tympani volume were calculated. Cochlear implantation in control diet subjects caused infiltration of cells, including macrophages, into the cochlea. Fibrosis was evident in the scala tympani adjacent to the electrode array. Mice fed PLX5622 chow showed reduced macrophage infiltration throughout the implanted cochleae across all time points. However, scala tympani fibrosis was not reduced relative to control diet subjects. Further, mice treated with PLX5622 showed increased electrode impedances compared to controls. Finally, treatment with PLX5622 decreased SGN survival in implanted and contralateral cochleae. CONCLUSION The data suggest that macrophages play an important role in modulating the intracochlear tissue response following CI and neural survival.
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Affiliation(s)
- Muhammad Taifur Rahman
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Brian J Mostaert
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Bryce Hunger
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Utsow Saha
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Alexander D Claussen
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Ibrahim Razu
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Farjana Nasrin
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Nashwaan Ali Khan
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Peter Eckard
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Sarah Coleman
- Department of Biostatistics, The University of Iowa, Iowa City, IA, USA
| | - Jacob Oleson
- Department of Biostatistics, The University of Iowa, Iowa City, IA, USA
| | | | - Keiko Hirose
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO, USA
| | - Marlan R Hansen
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA.
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15
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Delaney DS, Liew LJ, Lye J, Atlas MD, Wong EYM. Overcoming barriers: a review on innovations in drug delivery to the middle and inner ear. Front Pharmacol 2023; 14:1207141. [PMID: 37927600 PMCID: PMC10620978 DOI: 10.3389/fphar.2023.1207141] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 10/02/2023] [Indexed: 11/07/2023] Open
Abstract
Despite significant advances in the development of therapeutics for hearing loss, drug delivery to the middle and inner ear remains a challenge. As conventional oral or intravascular administration are ineffective due to poor bioavailability and impermeability of the blood-labyrinth-barrier, localized delivery is becoming a preferable approach for certain drugs. Even then, localized delivery to the ear precludes continual drug delivery due to the invasive and potentially traumatic procedures required to access the middle and inner ear. To address this, the preclinical development of controlled release therapeutics and drug delivery devices have greatly advanced, with some now showing promise clinically. This review will discuss the existing challenges in drug development for treating the most prevalent and damaging hearing disorders, in particular otitis media, perforation of the tympanic membrane, cholesteatoma and sensorineural hearing loss. We will then address novel developments in drug delivery that address these including novel controlled release therapeutics such as hydrogel and nanotechnology and finally, novel device delivery approaches such as microfluidic systems and cochlear prosthesis-mediated delivery. The aim of this review is to investigate how drugs can reach the middle and inner ear more efficiently and how recent innovations could be applied in aiding drug delivery in certain pathologic contexts.
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Affiliation(s)
- Derek S. Delaney
- Hearing Therapeutics, Ear Science Institute Australia, Nedlands, WA, Australia
- Faculty of Health Sciences, Curtin Health Innovation Research Institute, Curtin University, Bentley, WA, Australia
| | - Lawrence J. Liew
- Hearing Therapeutics, Ear Science Institute Australia, Nedlands, WA, Australia
- Centre for Ear Sciences, Medical School, The University of Western Australia, Nedlands, WA, Australia
| | - Joey Lye
- Hearing Therapeutics, Ear Science Institute Australia, Nedlands, WA, Australia
| | - Marcus D. Atlas
- Hearing Therapeutics, Ear Science Institute Australia, Nedlands, WA, Australia
- Centre for Ear Sciences, Medical School, The University of Western Australia, Nedlands, WA, Australia
- Faculty of Health Sciences, Curtin Medical School, Curtin University, Bentley, WA, Australia
| | - Elaine Y. M. Wong
- Hearing Therapeutics, Ear Science Institute Australia, Nedlands, WA, Australia
- Centre for Ear Sciences, Medical School, The University of Western Australia, Nedlands, WA, Australia
- Faculty of Health Sciences, Curtin Medical School, Curtin University, Bentley, WA, Australia
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16
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de Rijk SR, Boys AJ, Roberts IV, Jiang C, Garcia C, Owens RM, Bance M. Tissue-Engineered Cochlear Fibrosis Model Links Complex Impedance to Fibrosis Formation for Cochlear Implant Patients. Adv Healthc Mater 2023; 12:e2300732. [PMID: 37310792 DOI: 10.1002/adhm.202300732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 05/30/2023] [Indexed: 06/15/2023]
Abstract
Cochlear implants are a life-changing technology for those with severe sensorineural hearing loss, partially restoring hearing through direct electrical stimulation of the auditory nerve. However, they are known to elicit an immune response resulting in fibrotic tissue formation in the cochlea that is linked to residual hearing loss and suboptimal outcomes. Intracochlear fibrosis is difficult to track without postmortem histology, and no specific electrical marker for fibrosis exists. In this study, a tissue-engineered model of cochlear fibrosis is developed following implant placement to examine the electrical characteristics associated with fibrotic tissue formation around electrodes. The model is characterized using electrochemical impedance spectroscopy and an increase in the resistance and a decrease in capacitance of the tissue using a representative circuit are found. This result informs a new marker of fibrosis progression over time that is extractable from voltage waveform responses, which can be directly measured in cochlear implant patients. This marker is tested in a small sample size of recently implanted cochlear implant patients, showing a significant increase over two postoperative timepoints. Using this system, complex impedance is demonstrated as a marker of fibrosis progression that is directly measurable from cochlear implants to enable real-time tracking of fibrosis formation in patients, creating opportunities for earlier treatment intervention to improve cochlear implant efficacy.
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Affiliation(s)
- Simone R de Rijk
- Cambridge Hearing Group, Cambridge, CB2 8AF, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 3 EB, UK
| | - Alexander J Boys
- Cambridge Hearing Group, Cambridge, CB2 8AF, UK
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, UK
| | - Iwan V Roberts
- Cambridge Hearing Group, Cambridge, CB2 8AF, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 3 EB, UK
| | - Chen Jiang
- Cambridge Hearing Group, Cambridge, CB2 8AF, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 3 EB, UK
- Department of Electronic Engineering, Tsinghua University, Beijing, 100190, P. R. China
| | - Charlotte Garcia
- Cambridge Hearing Group, Cambridge, CB2 8AF, UK
- Medical Research Council Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, CB2 7EF, UK
| | - Róisín M Owens
- Cambridge Hearing Group, Cambridge, CB2 8AF, UK
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, UK
| | - Manohar Bance
- Cambridge Hearing Group, Cambridge, CB2 8AF, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 3 EB, UK
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17
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Braack KJ, Miles T, Amat F, Brown DJ, Atlas MD, Kuthubutheen J, Mulders WH, Prêle CM. Using x-ray micro computed tomography to quantify intracochlear fibrosis after cochlear implantation in a Guinea pig model. Heliyon 2023; 9:e19343. [PMID: 37662829 PMCID: PMC10474428 DOI: 10.1016/j.heliyon.2023.e19343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 08/07/2023] [Accepted: 08/18/2023] [Indexed: 09/05/2023] Open
Abstract
Cochlear implants (CIs) allow individuals with profound hearing loss to understand speech and perceive sounds. However, not all patients obtain the full benefits that CIs can provide and the cause of this disparity is not fully understood. One possible factor for the variability in outcomes after cochlear implantation, is the development of fibrotic scar tissue around the implanted electrode. It has been hypothesised that limiting the extent of fibrosis after implantation may improve overall CI function, and longevity of the device. Currently, histology is often used to quantify the extent of intracochlear tissue growth after implantation however this method is labour intensive, time-consuming, often involves significant user bias, and causes physical distortion of the fibrosis. Therefore, this study aimed to evaluate x-ray micro computed tomography (μCT) as a method to measure the amount and distribution of fibrosis in a guinea pig model of cochlear implantation. Adult guinea pigs were implanted with an inactive electrode, and cochleae harvested eight weeks later (n = 7) and analysed using μCT, to quantify the extent of tissue reaction, followed by histological analysis to confirm that the tissue was indeed fibrotic. Cochleae harvested from an additional six animals following implantation were analysed by μCT, before and after contrast staining with osmium tetroxide (OsO4), to enhance the visualisation of soft tissues within the cochlea, including the tissue reaction. Independent analysis by two observers showed that the quantification method was robust and provided additional information on the distribution of the response within the cochlea. Histological analysis revealed that μCT visualised dense collagenous material and new bone formation but did not capture loose, areolar fibrotic tissue. Treatment with OsO4 significantly enhanced the visible tissue reaction detected using μCT. Overall, μCT is an alternative and reliable method that can be used to quantify the extent of the CI-induced intracochlear tissue response and will be a useful tool for the in vivo assessment of novel anti-fibrotic treatments.
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Affiliation(s)
- Kady J. Braack
- School of Human Sciences, University of Western Australia, Crawley, WA 6009, Australia
| | - Tylah Miles
- Institute for Respiratory Health, University of Western Australia, Nedlands, WA 6009, Australia
| | - Farah Amat
- School of Human Sciences, University of Western Australia, Crawley, WA 6009, Australia
| | - Daniel J. Brown
- Curtin Medical School, Curtin University, Bentley, WA 6102, Australia
| | - Marcus D. Atlas
- Curtin Medical School, Curtin University, Bentley, WA 6102, Australia
- Medical School, University of Western Australia, Crawley, WA 6009, Australia
- Ear Science Institute Australia, Subiaco, WA 6008, Australia
| | - Jafri Kuthubutheen
- Medical School, University of Western Australia, Crawley, WA 6009, Australia
- Department of Otolaryngology Head and Neck Surgery, Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, WA 6009, Australia
| | | | - Cecilia M. Prêle
- Institute for Respiratory Health, University of Western Australia, Nedlands, WA 6009, Australia
- Ear Science Institute Australia, Subiaco, WA 6008, Australia
- School of Medical, Molecular and Forensic Sciences, Murdoch University, Murdoch, WA 6150, Australia
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18
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Ardıç FN, Aydemir G, Tümkaya F, Altınöz E, Şenol H. The Effect of Intracochlear and Intratympanic Dexamethasone on Cochlear Implant Impedance. Turk Arch Otorhinolaryngol 2023; 61:103-108. [PMID: 38020414 PMCID: PMC10652048 DOI: 10.4274/tao.2023.2023-6-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Accepted: 08/12/2023] [Indexed: 12/01/2023] Open
Abstract
Objective This study investigated the impact of different local corticosteroid applications on impedance measurements in patients with cochlear implants. Methods The study was designed as a controlled, randomized, and prospective study in which 34 consecutive patients who had undergone cochlear implant surgery were divided into three groups. The first group received intracochlear dexamethasone, in the second group the middle ear cavity was filled with dexamethasone, and the third group did not receive dexamethasone. Intraoperative, postoperative 1st week, 1st month, 3rd month, 6th-month neural response telemetry, and impedances were measured. The measurements were compared by electrode groups representing the different regions of cochlea like basal (1-7), middle (8-13), and apical (14-22) regions. Results The intergroup analysis showed no statistically significant differences in impedance measurements of the basal, middle, and apical regions (p>0.05). However, the impedances were lower in the two dexamethasone groups, especially in the basal and middle parts. Sixth month impedances were also lower in the dexamethasone groups. There was apparent stability in the impedance of the basal region with the intracochlear application during the first week. Conclusion Local dexamethasone applications had a potentially positive impact on the impedance of the basal and middle regions. Patients had lower impedances than the control group during follow-up and at the endpoint. The increase in the apical region may indicate that dexamethasone was not reaching the apical zone in local applications.
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Affiliation(s)
- Fazıl Necdet Ardıç
- Department of Otolaryngology-Head and Neck Surgery, Pamukkale University Faculty of Medicine, Denizli, Turkey
| | - Gökçe Aydemir
- Department of Otolaryngology-Head and Neck Surgery, Pamukkale University Faculty of Medicine, Denizli, Turkey
| | - Funda Tümkaya
- Department of Otolaryngology-Head and Neck Surgery, Pamukkale University Faculty of Medicine, Denizli, Turkey
| | - Ece Altınöz
- Department of Otolaryngology-Head and Neck Surgery, Pamukkale University Faculty of Medicine, Denizli, Turkey
| | - Hande Şenol
- Department of Biostatistics, Pamukkale University Faculty of Medicine, Denizli, Turkey
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Ernst BP, Heinrich UR, Fries M, Meuser R, Rader T, Eckrich J, Stauber RH, Strieth S. Cochlear implantation impairs intracochlear microcirculation and counteracts iNOS induction in guinea pigs. Front Cell Neurosci 2023; 17:1189980. [PMID: 37448696 PMCID: PMC10336219 DOI: 10.3389/fncel.2023.1189980] [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: 03/20/2023] [Accepted: 06/06/2023] [Indexed: 07/15/2023] Open
Abstract
Introduction Preservation of residual hearing remains a great challenge during cochlear implantation. Cochlear implant (CI) electrode array insertion induces changes in the microvasculature as well as nitric oxide (NO)-dependent vessel dysfunction which have been identified as possible mediators of residual hearing loss after cochlear implantation. Methods A total of 24 guinea pigs were randomized to receive either a CI (n = 12) or a sham procedure (sham) by performing a cochleostomy without electrode array insertion (n = 12). The hearing threshold was determined using frequency-specific compound action potentials. To gain visual access to the stria vascularis, a microscopic window was created in the osseous cochlear lateral wall. Cochlear blood flow (CBF) and cochlear microvascular permeability (CMP) were evaluated immediately after treatment, as well as after 1 and 2 h, respectively. Finally, cochleae were resected for subsequent immunohistochemical analysis of the iNOS expression. Results The sham control group showed no change in mean CBF after 1 h (104.2 ± 0.7%) and 2 h (100.8 ± 3.6%) compared to baseline. In contrast, cochlear implantation resulted in a significant continuous decrease in CBF after 1 h (78.8 ± 8.1%, p < 0.001) and 2 h (60.6 ± 11.3%, p < 0.001). Additionally, the CI group exhibited a significantly increased CMP (+44.9% compared to baseline, p < 0.0001) and a significant increase in median hearing threshold (20.4 vs. 2.5 dB SPL, p = 0.0009) compared to sham after 2 h. Intriguingly, the CI group showed significantly lower iNOS-expression levels in the organ of Corti (329.5 vs. 54.33 AU, p = 0.0003), stria vascularis (596.7 vs. 48.51 AU, p < 0.0001), interdental cells (564.0 vs. 109.1 AU, p = 0.0003) and limbus fibrocytes (119.4 vs. 18.69 AU, p = 0.0286). Conclusion Mechanical and NO-dependent microvascular dysfunction seem to play a pivotal role in residual hearing loss after CI electrode array insertion. This may be facilitated by the implantation associated decrease in iNOS expression. Therefore, stabilization of cochlear microcirculation could be a therapeutic strategy to preserve residual hearing.
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Affiliation(s)
| | - Ulf-Rüdiger Heinrich
- Department of Otorhinolaryngology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Mathias Fries
- Department of Otorhinolaryngology, University Medical Center Bonn (UKB), Bonn, Germany
| | - Regina Meuser
- Institute for Medical Biometry, Epidemiology and Informatics (IMBEI), University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Tobias Rader
- Division of Audiology, Department of Otorhinolaryngology, University Hospital, Ludwig-Maximilians-Universität München (LMU), Munich, Germany
| | - Jonas Eckrich
- Department of Otorhinolaryngology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Roland H. Stauber
- Department of Otorhinolaryngology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Sebastian Strieth
- Department of Otorhinolaryngology, University Medical Center Bonn (UKB), Bonn, Germany
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Rahman MT, Mostaert BJ, Hunger B, Saha U, Claussen AD, Razu I, Farjana N, Khan NA, Coleman S, Oleson J, Kirk J, Keiko H, Hansen MR. Contribution of macrophages to intracochlear tissue remodeling responses following cochlear implantation and neural survival. RESEARCH SQUARE 2023:rs.3.rs-3065630. [PMID: 37461619 PMCID: PMC10350110 DOI: 10.21203/rs.3.rs-3065630/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/24/2023]
Abstract
Introduction Cochlear implants (CIs) restore hearing to deafened patients. The foreign body response (FBR) following cochlear implantation (post-CI) comprises an infiltration of macrophages, other immune and non-immune cells, and fibrosis into the scala tympani; a space that is normally devoid of cells. This FBR is associated with negative effects on CI outcomes including increased electrode impedances and loss of residual acoustic hearing. This study investigates the extent to which macrophage depletion by an orally administered CSF-1R specific kinase (c-FMS) inhibitor, PLX-5622, modulates the tissue response to CI and neural health. Materials and methods 10-12-week-old CX3CR1+/GFP Thy1+/YFP mice on C57Bl6 background with normal hearing were fed chow containing 1200 mg/kg PLX5622 or control chow for the duration of the study. 7-days after starting the diet, 3-channel cochlear implants were implanted ear via the round window. Serial impedance and neural response telemetry (NRT) measurements were acquired throughout the study. Electric stimulation began 7 days post-CI until 28- days post-CI for 5 hrs/day, 5 days/week, with programming guided by NRT and behavioral responses. Cochleae harvested at 10-, 28- or 56-days post-CI were cryosectioned and labeled with antibody against α-smooth muscle actin (α-SMA) to identify myofibroblasts and quantify the fibrotic response. Using IMARIS image analysis software, the outlines of scala tympani, Rosenthal canal, modiolus and lateral wall for each turn were traced manually to measure region volume. Density of nuclei, CX3CR1+ macrophages, Thy1+ spiral ganglion neuron (SGN) numbers and ratio of volume of α-SMA+ space/volume of scala tympani were calculated. Results Cochlear implantation in control diet subjects caused infiltration of cells, including macrophages, into the cochlea: this response was initially diffuse throughout the cochlea and later localized to the scala tympani of the basal turn by 56-days post-CI. Fibrosis was evident in the scala tympani adjacent to the electrode array. Mice fed PLX5622 chow showed reduced macrophage infiltration throughout the implanted cochleae across all timepoints. However, scala tympani fibrosis was not reduced relative to control diet subjects. Further, mice treated with PLX5622 showed increased electrode impedances compared to controls. Finally, treatment with PLX5622 decreased SGN survival in implanted and contralateral cochleae. Discussion The data suggest that macrophages play an important role in modulating the intracochlear tissue response following CI and neural survival.
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Affiliation(s)
| | - Brain J Mostaert
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Bryce Hunger
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Utsow Saha
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | | | - Ibrahim Razu
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Nasrin Farjana
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Nashwaan Ali Khan
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Sarah Coleman
- Department of Statistics, The University of Iowa, IA
| | - Jackob Oleson
- Department of Statistics, The University of Iowa, IA
| | | | - Hirose Keiko
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St Louis, MO
| | - Marlan R Hansen
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
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21
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Schraivogel S, Aebischer P, Weder S, Caversaccio M, Wimmer W. Cochlear implant electrode impedance subcomponents as biomarker for residual hearing. Front Neurol 2023; 14:1183116. [PMID: 37288065 PMCID: PMC10242064 DOI: 10.3389/fneur.2023.1183116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 04/25/2023] [Indexed: 06/09/2023] Open
Abstract
Introduction and objectives Maintaining the structural integrity of the cochlea and preserving residual hearing is crucial for patients, especially for those for whom electric acoustic stimulation is intended. Impedances could reflect trauma due to electrode array insertion and therefore could serve as a biomarker for residual hearing. The aim of this study is to evaluate the association between residual hearing and estimated impedance subcomponents in a known collective from an exploratory study. Methods A total of 42 patients with lateral wall electrode arrays from the same manufacturer were included in the study. For each patient, we used data from audiological measurements to compute residual hearing, impedance telemetry recordings to estimate near and far-field impedances using an approximation model, and computed tomography scans to extract anatomical information about the cochlea. We assessed the association between residual hearing and impedance subcomponent data using linear mixed-effects models. Results The progression of impedance subcomponents showed that far-field impedance was stable over time compared to near-field impedance. Low-frequency residual hearing demonstrated the progressive nature of hearing loss, with 48% of patients showing full or partial hearing preservation after 6 months of follow-up. Analysis revealed a statistically significant negative effect of near-field impedance on residual hearing (-3.81 dB HL per kΩ; p < 0.001). No significant effect of far-field impedance was found. Conclusion Our findings suggest that near-field impedance offers higher specificity for residual hearing monitoring, while far-field impedance was not significantly associated with residual hearing. These results highlight the potential of impedance subcomponents as objective biomarkers for outcome monitoring in cochlear implantation.
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Affiliation(s)
- Stephan Schraivogel
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
- Department of ENT—Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Philipp Aebischer
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
- Department of ENT—Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Stefan Weder
- Department of ENT—Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Marco Caversaccio
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
- Department of ENT—Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Wilhelm Wimmer
- Department of ENT—Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Department of Otorhinolaryngology, TUM School of Medicine, Klinikum Rechts der Isar, Technical University of Munich, Munich, Germany
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Findlay C, Edwards M, Hough K, Grasmeder M, Newman TA. Leveraging real-world data to improve cochlear implant outcomes: Is the data available? Cochlear Implants Int 2023:1-12. [PMID: 37088565 DOI: 10.1080/14670100.2023.2198792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
OBJECTIVES A small but persistent proportion of individuals do not gain the expected benefit from cochlear implants(CI). A step-change in the understanding of factors affecting outcomes could come through data science. This study evaluates clinical data capture to assess the quality and utility of CI user's health records for data science, by assessing the recording of otitis media. Otitis media was selected as it is associated with the development of sensorineural hearing loss and may affect cochlear implant outcomes. METHODS A retrospective service improvement project evaluating the medical records of 594 people with a CI under the care of the University of Southampton Auditory Implant Service between 2014 and 2020. RESULTS The clinical records are suitable for data science research. Of the cohort studied 20% of Adults and more than 40% of the paediatric cases have a history of middle ear inflammation. DISCUSSION Data science has potential to improve cochlear implant outcomes and improve understanding of the mechanisms underlying poor performance, through retrospective secondary analysis of real-world data. CONCLUSION Implant centres and the British Cochlear Implant Group National Hearing Implant Registry are urged to consider the importance of consistently and accurate recording of patient data over time for each CI user. Data where links to hearing loss have been identified, such as middle ear inflammation, may be particularly valuable in future analyses and to inform clinical trials.
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Affiliation(s)
- Callum Findlay
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Building 85, Highfield Campus, Southampton S017 1BJ, UK
- Department of Otolaryngology, University Hospital Southampton NHS FT, Tremona Road, Southampton SO16 6YD, UK
| | - Mathew Edwards
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Building 85, Highfield Campus, Southampton S017 1BJ, UK
| | - Kate Hough
- Faculty of Engineering and Physical Sciences, Highfield Campus, University of Southampton, Building 85, Southampton, UK
| | - Mary Grasmeder
- Faculty of Physical Sciences, Highfield Campus, University of Southampton Auditory Implant Services, B19, Southampton SO171BJ, UK
| | - Tracey A Newman
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Building 85, Highfield Campus, Southampton S017 1BJ, UK
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Wellens J, Deschaume O, Putzeys T, Eyley S, Thielemans W, Verhaert N, Bartic C. Sulfobetaine-based ultrathin coatings as effective antifouling layers for implantable neuroprosthetic devices. Biosens Bioelectron 2023; 226:115121. [PMID: 36774733 DOI: 10.1016/j.bios.2023.115121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 01/30/2023] [Accepted: 02/02/2023] [Indexed: 02/05/2023]
Abstract
Foreign body response (FBR), inflammation, and fibrotic encapsulation of neural implants remain major problems affecting the impedance of the electrode-tissue interface and altering the device performance. Adhesion of proteins and cells (e.g., pro-inflammatory macrophages, and fibroblasts) triggers the FBR cascade and can be diminished by applying antifouling coatings onto the implanted devices. In this paper, we report the deposition and characterization of a thin (±6 nm) sulfobetaine-based coating onto microfabricated platinum electrodes and cochlear implant (CI) electrode arrays. We found that this coating has stable cell and protein-repellent properties, for at least 31 days in vitro, not affected by electrical stimulation protocols. Additionally, its effect on the electrochemical properties relevant to stimulation (i.e., impedance, charge injection capacity) was negligible. When applied to clinical CI electrode arrays, the film was successful at inhibiting fibroblast adhesion on both the silicone packaging and the platinum/iridium electrodes. In vitro, in fibroblast cultures, coated CI electrode arrays maintained impedance values up to five times lower compared to non-coated devices. Our studies demonstrate that such thin sulfobetaine containing layers are stable and prevent protein and cell adhesion in vitro and are compatible for use on CI electrode arrays. Future in vivo studies should be conducted to investigate its ability to mitigate biofouling, fibrosis, and the resulting impedance changes upon long-term implantation in vivo.
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Affiliation(s)
- Jolan Wellens
- Laboratory for Soft Matter and Biophysics, Dept. Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001, Leuven, Belgium
| | - Olivier Deschaume
- Laboratory for Soft Matter and Biophysics, Dept. Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001, Leuven, Belgium
| | - Tristan Putzeys
- Laboratory for Soft Matter and Biophysics, Dept. Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001, Leuven, Belgium; Experimental Oto-rhino-laryngology Research Group, Dept. Neuroscience, KU Leuven, Herestraat 49, 3000, Leuven, Belgium
| | - Samuel Eyley
- Sustainable Materials Lab, Department of Chemical Engineering, KU Leuven, Campus Kulak Kortrijk, Etienne Sabbelaan 53, 8500, Kortrijk, Belgium
| | - Wim Thielemans
- Sustainable Materials Lab, Department of Chemical Engineering, KU Leuven, Campus Kulak Kortrijk, Etienne Sabbelaan 53, 8500, Kortrijk, Belgium
| | - Nicolas Verhaert
- Experimental Oto-rhino-laryngology Research Group, Dept. Neuroscience, KU Leuven, Herestraat 49, 3000, Leuven, Belgium; Department of Otorhinolaryngology, University Hospitals Leuven, Herestraat 49, 3000, Leuven, Belgium
| | - Carmen Bartic
- Laboratory for Soft Matter and Biophysics, Dept. Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001, Leuven, Belgium.
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Hashemi SB, Janipour M, Jahangiri R, Babaei A. The effect of cochlear implant insertion technique on post-operative neural response telemetry and impedance in paediatric patients. J Laryngol Otol 2023; 137:363-367. [PMID: 35445650 DOI: 10.1017/s0022215122000901] [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] [Indexed: 11/06/2022]
Abstract
OBJECTIVE This study aimed to compare neural response telemetry and impedance between the round window and cochleostomy approaches for cochlear implantation. METHODS In this case-control study, 64 patients aged less than 3.5 years underwent cochlear implantation via the round window or cochleostomy approach. Post-operative neural response telemetry and impedance were measured. RESULTS The impedance measurements at electrodes 1, 11 and 22 showed no significant differences between the two groups three months after implantation (p = 0.90, p = 0.08 and p = 0.37, respectively). Similar results were observed six months after implantation (p = 0.71, p = 0.65 and p = 0.70, respectively). There was no significant difference in neural response telemetry between the two groups after three months. The neural response telemetry of electrode 1 in the cochleostomy group (171.26 ± 19.81 μV) was significantly higher in comparison with that of electrode 1 in the round window group (161.97 ± 12.71 μV) after six months (p = 0.03). The neural response telemetry values for electrodes 11 and 22 did not show any significant difference after six months (p = 0.14 and p = 0.48, respectively). CONCLUSION Both approaches provide equal stimulation of the cochlear nerve and impedance.
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Affiliation(s)
- S B Hashemi
- Otolaryngology Research Centre, Department of Otolaryngology, Shiraz University of Medical Sciences, Shiraz, Iran
| | - M Janipour
- Otolaryngology Research Centre, Department of Otolaryngology, Shiraz University of Medical Sciences, Shiraz, Iran
| | - R Jahangiri
- Otolaryngology Research Centre, Department of Otolaryngology, Shiraz University of Medical Sciences, Shiraz, Iran
| | - A Babaei
- Otolaryngology Research Centre, Department of Otolaryngology, Shiraz University of Medical Sciences, Shiraz, Iran
- Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
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Pisa JFD, Almutairi WH, Mackie K, Stangherlin D, Sulkers J, Hochman JB. Impedance Change as an Indicator of Cochlear Implant Failure. Otol Neurotol 2023; 44:e211-e215. [PMID: 36764700 DOI: 10.1097/mao.0000000000003819] [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: 02/12/2023]
Abstract
OBJECTIVE In February 2020, Advanced Bionics initiated a field action notice to remove the MS Ultra (V1) implant from circulation. In this study, we quantify a single site's incidence with device failure and examine the relationship between impedance change and declining speech perception. STUDY DESIGN Retrospective/cohort study. SETTING Tertiary healthcare center. PATIENTS Forty-nine adult patients (52 devices) were implanted between October 2017 and December 2019, with the following exclusion criteria: <18 years of age, medical/surgical failures, and lack of English-language proficiency. INTERVENTIONS Diagnostic. MAIN OUTCOME MEASURES Postoperative speech perception (AzBio sentence test) scores at 12 months postactivation were compared with repeat testing at 6- to 12-month intervals. Degree of change in impedances from 1 month postactivation was analyzed at similar intervals. Device failures were suspected when impedance levels on three or more electrodes dropped to <3.5 kΩ and AzBio scores declined >15%. Device failures were confirmed through analyses completed by the manufacturer. RESULTS To date, 21% (11/52) of devices have met all three criteria for a confirmed failure with an average decline in speech perception of 27.7 ± 22%. The average length of time for detection of device failure was 21.9 ± 5 months postimplantation. An additional 7 devices (13%) are currently being monitored for failure but have not yet met full criteria. There was no predictive relationship between degree of impedance change and speech perception scores. Electrodes along the entire array (channels 1-16) can be affected. CONCLUSIONS Impedance values can be used as a reliable indicator of device malfunction, thus facilitating patient counseling and early intervention. No correlation was identified between impedance changes and speech perception scores.
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Affiliation(s)
| | | | - Kristy Mackie
- Central Speech and Hearing Clinic, Winnipeg, Manitoba, Canada
| | | | - Jacob Sulkers
- Central Speech and Hearing Clinic, Winnipeg, Manitoba, Canada
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Eftekharian A, Khajavi M, Moghadam S, Eftekharian K, Azadeh Ranjbar L, Rezaei A. Comparison Between the Effect of Intra-Scalar Methylprednisolone and Sodium Hyaluronate in Impedance and Electrically Evoked Compound Action Potentials in Cochlear Implant Patients. Indian J Otolaryngol Head Neck Surg 2023; 75:285-290. [PMID: 37206779 PMCID: PMC10188670 DOI: 10.1007/s12070-022-03429-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 12/18/2022] [Indexed: 01/01/2023] Open
Abstract
To evaluate and compare the effect of intra-scalar methylprednisolone and sodium hyaluronate on cochlear implants' impedance and electrically evoked compound action potentials thresholds. In a prospective randomized clinical trial, 103 children with pre-lingual hearing loss candidates for cochlear implantation at a tertiary hospital were divided into three groups based on intervention. Intraoperatively, one group received intra-scalar methylprednisolone, the second sodium hyaluronate, and the third group was the control group. Impedance and electrically evoked compound action potentials (e-ECAP) thresholds on long-term follow-up were evaluated and compared in these three groups. Significant decrease in impedance and e-ECAP thresholds were observed in all groups in a 4-year follow-up. No statistically significant difference was observed among all mentioned groups. Impedance and e-ECAP thresholds decrease in the long term, and using topical intra-scalar Healon or methylprednisolone may not significantly affect these parameters.
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Affiliation(s)
- Ali Eftekharian
- Hearing Disorders Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mahdi Khajavi
- Hearing Disorders Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Soodabeh Moghadam
- Hearing Disorders Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Kourosh Eftekharian
- Hearing Disorders Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Leyla Azadeh Ranjbar
- Hearing Disorders Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Alireza Rezaei
- Hearing Disorders Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Dual Drug Delivery in Cochlear Implants: In Vivo Study of Dexamethasone Combined with Diclofenac or Immunophilin Inhibitor MM284 in Guinea Pigs. Pharmaceutics 2023; 15:pharmaceutics15030726. [PMID: 36986587 PMCID: PMC10058822 DOI: 10.3390/pharmaceutics15030726] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 02/20/2023] [Accepted: 02/21/2023] [Indexed: 02/24/2023] Open
Abstract
Cochlear implants are well established to treat severe hearing impairments. Despite many different approaches to reduce the formation of connective tissue after electrode insertion and to keep electrical impedances low, results are not yet satisfying. Therefore, the aim of the current study was to combine the incorporation of 5% dexamethasone in the silicone body of the electrode array with an additional polymeric coating releasing diclofenac or the immunophilin inhibitor MM284, some anti-inflammatory substances not yet tested in the inner ear. Guinea pigs were implanted for four weeks and hearing thresholds were determined before implantation and after the observation time. Impedances were monitored over time and, finally, connective tissue and the survival of spiral ganglion neurons (SGNs) were quantified. Impedances increased in all groups to a similar extent but this increase was delayed in the groups with an additional release of diclofenac or MM284. Using Poly-L-lactide (PLLA)-coated electrodes, the damage caused during insertion was much higher than without the coating. Only in these groups, connective tissue could extend to the apex of the cochlea. Despite this, numbers of SGNs were only reduced in PLLA and PLLA plus diclofenac groups. Even though the polymeric coating was not flexible enough, MM284 seems to especially have potential for further evaluation in connection with cochlear implantation.
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28
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Lambriks L, van Hoof M, Debruyne J, Janssen M, Hof J, Hellingman K, Devocht E, George E. Toward neural health measurements for cochlear implantation: The relationship among electrode positioning, the electrically evoked action potential, impedances and behavioral stimulation levels. Front Neurol 2023; 14:1093265. [PMID: 36846130 PMCID: PMC9948626 DOI: 10.3389/fneur.2023.1093265] [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: 11/08/2022] [Accepted: 01/10/2023] [Indexed: 02/11/2023] Open
Abstract
Introduction Estimating differences in neural health across different sites within the individual cochlea potentially enables clinical applications for subjects with a cochlear implant. The electrically evoked compound action potential (ECAP) is a measure of neural excitability that possibly provides an indication of a neural condition. There are many factors, however, that affect this measure and increase the uncertainty of its interpretation. To better characterize the ECAP response, its relationship with electrode positioning, impedances, and behavioral stimulation levels was explored. Methods A total of 14 adult subjects implanted with an Advanced Bionics cochlear electrode array were prospectively followed up from surgery to 6 months postoperative. Insertion depth, distance to the modiolus, and distance to the medial wall were assessed for each electrode by postoperative CT analysis. ECAPs were measured intraoperatively and at three visits postoperatively on all 16 electrodes using the NRI feature of clinical programming software and characterized using multiple parameters. Impedances and behavioral stimulation levels were measured at every fitting session. Results Patterns in ECAPs and impedances were consistent over time, but high variability existed among subjects and between different positions in the cochlea. Electrodes located closer to the apex of the cochlea and closer to the modiolus generally showed higher neural excitation and higher impedances. Maximum loudness comfort levels were correlated strongly with the level of current needed to elicit a response of 100 μV ECAP. Conclusion Multiple factors contribute to the ECAP response in subjects with a cochlear implant. Further research might address whether the ECAP parameters used in this study will benefit clinical electrode fitting or the assessment of auditory neuron integrity.
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Affiliation(s)
- Lars Lambriks
- Department of ENT/Audiology, School for Mental Health and NeuroScience, Maastricht University Medical Centre, Maastricht, Netherlands,*Correspondence: Lars Lambriks ✉
| | - Marc van Hoof
- Department of ENT/Audiology, School for Mental Health and NeuroScience, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Joke Debruyne
- Department of ENT/Audiology, School for Mental Health and NeuroScience, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Miranda Janssen
- Department of ENT/Audiology, School for Mental Health and NeuroScience, Maastricht University Medical Centre, Maastricht, Netherlands,Department of Methodology and Statistics, Care and Public Health Research Institute, Maastricht University, Maastricht, Netherlands
| | - Janny Hof
- Department of ENT/Audiology, School for Mental Health and NeuroScience, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Katja Hellingman
- Department of ENT/Audiology, School for Mental Health and NeuroScience, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Elke Devocht
- Department of ENT/Audiology, School for Mental Health and NeuroScience, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Erwin George
- Department of ENT/Audiology, School for Mental Health and NeuroScience, Maastricht University Medical Centre, Maastricht, Netherlands
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Schvartz-Leyzac KC, Colesa DJ, Swiderski DL, Raphael Y, Pfingst BE. Cochlear Health and Cochlear-implant Function. J Assoc Res Otolaryngol 2023; 24:5-29. [PMID: 36600147 PMCID: PMC9971430 DOI: 10.1007/s10162-022-00882-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 11/24/2022] [Indexed: 01/06/2023] Open
Abstract
The cochlear implant (CI) is widely considered to be one of the most innovative and successful neuroprosthetic treatments developed to date. Although outcomes vary, CIs are able to effectively improve hearing in nearly all recipients and can substantially improve speech understanding and quality of life for patients with significant hearing loss. A wealth of research has focused on underlying factors that contribute to success with a CI, and recent evidence suggests that the overall health of the cochlea could potentially play a larger role than previously recognized. This article defines and reviews attributes of cochlear health and describes procedures to evaluate cochlear health in humans and animal models in order to examine the effects of cochlear health on performance with a CI. Lastly, we describe how future biologic approaches can be used to preserve and/or enhance cochlear health in order to maximize performance for individual CI recipients.
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Affiliation(s)
- Kara C Schvartz-Leyzac
- Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, Kresge Hearing Research Institute, University of Michigan, 1150 Medical Center Drive, Ann Arbor, MI, 48109-5616, USA
- Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Ave, Charleston, SC, 29425, USA
| | - Deborah J Colesa
- Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, Kresge Hearing Research Institute, University of Michigan, 1150 Medical Center Drive, Ann Arbor, MI, 48109-5616, USA
| | - Donald L Swiderski
- Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, Kresge Hearing Research Institute, University of Michigan, 1150 Medical Center Drive, Ann Arbor, MI, 48109-5616, USA
| | - Yehoash Raphael
- Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, Kresge Hearing Research Institute, University of Michigan, 1150 Medical Center Drive, Ann Arbor, MI, 48109-5616, USA
| | - Bryan E Pfingst
- Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, Kresge Hearing Research Institute, University of Michigan, 1150 Medical Center Drive, Ann Arbor, MI, 48109-5616, USA.
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Goblet M, Lenarz T, Paasche G. Effect of Immunophilin Inhibitors on Cochlear Fibroblasts and Spiral Ganglion Cells. Audiol Neurootol 2023; 28:43-51. [PMID: 36075188 PMCID: PMC9909619 DOI: 10.1159/000526454] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 08/02/2022] [Indexed: 01/20/2023] Open
Abstract
INTRODUCTION Loss of hair cells and degeneration of spiral ganglion neurons (SGN) lead to severe hearing loss or deafness. The successful use of a cochlear implant (CI) depends among other factors on the number of surviving SGN. Postoperative formation of fibrous tissue around the electrode array causes an increase in electrical impedances at the stimulating contacts. The use of immunophilin inhibitors may reduce the inflammatory processes without suppressing the immune response. Here, we report on in vitro experiments with different concentrations of immunophilin inhibitors MM284 and compound V20 regarding a possible application of these substances in the inner ear. METHODS Standard cell lines (NIH/3T3 fibroblasts), freshly isolated SGN, and fibroblasts from neonatal rat cochleae (p3-5) were incubated with different concentrations of immunophilin inhibitors for 48 h. Metabolic activity of fibroblasts was investigated by MTT assay and cell survival by counting of immunochemically stained neurons and compared to controls. RESULTS MM284 did not affect SGN numbers and neurite growth at concentrations of 4 × 10-5 mol/L and below, whereas V20 had no effect at 8 × 10-6 mol/L and below. Metabolic activity of fibroblasts was unchanged at these concentrations. CONCLUSION Especially MM284 might be considered as a possible candidate for application within the cochlea.
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Affiliation(s)
- Madeleine Goblet
- Department of Otorhinolaryngology, Hannover Medical School, Hannover, Germany
| | - Thomas Lenarz
- Department of Otorhinolaryngology, Hannover Medical School, Hannover, Germany,Hearing4all Cluster of Excellence, Hannover Medical School, Hannover, Germany
| | - Gerrit Paasche
- Department of Otorhinolaryngology, Hannover Medical School, Hannover, Germany,Hearing4all Cluster of Excellence, Hannover Medical School, Hannover, Germany,*Gerrit Paasche,
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Electrocochleographic Patterns Predicting Increased Impedances and Hearing Loss after Cochlear Implantation. Ear Hear 2022:00003446-990000000-00095. [PMID: 36550618 DOI: 10.1097/aud.0000000000001319] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
OBJECTIVES Different patterns of electrocochleographic responses along the electrode array after insertion of the cochlear implant electrode array have been described. However, the implications of these patterns remain unclear. Therefore, the aim of the study was to correlate different peri- and postoperative electrocochleographic patterns with four-point impedance measurements and preservation of residual hearing. DESIGN Thirty-nine subjects with residual low-frequency hearing which were implanted with a slim-straight electrode array could prospectively be included. Intracochlear electrocochleographic recordings and four-point impedance measurements along the 22 electrodes of the array (EL, most apical EL22) were conducted immediately after complete insertion and 3 months after surgery. Hearing preservation was assessed after 3 months. RESULTS In perioperative electrocochleographic recordings, 22 subjects (56%) showed the largest amplitude around the tip of the electrode array (apical-peak, AP, EL20 or EL22), whereas 17 subjects (44%) exhibited a maximum amplitude in more basal regions (mid-peak, MP, EL18 or lower). At 3 months, in six subjects with an AP pattern perioperatively, the location of the largest electrocochleographic response had shifted basally (apical-to-mid-peak, AP-MP). Latency was analyzed along the electrode array when this could be discerned. This was the case in 68 peri- and postoperative recordings (87% of all recordings, n = 78). The latency increased with increasing insertion depth in AP recordings (n = 38, median of EL with maximum latency shift = EL21). In MP recordings (n = 30), the maximum latency shift was detectable more basally (median EL12, p < 0.001). Four-point impedance measurements were available at both time points in 90% (n = 35) of all subjects. At the 3-month time point, recordings revealed lower impedances in the AP group (n = 15, mean = 222 Ω, SD = 63) than in the MP (n = 14, mean = 295 Ω, SD= 7 6) and AP-MP groups (n = 6, mean = 234 Ω, SD = 129; AP versus MP p = 0.026, AP versus AP-MP p = 0.023, MP versus AP-MP p > 0.999). The amplitudes of perioperative AP recordings showed a correlation with preoperative hearing thresholds (r2=0.351, p = 0.004). No such correlation was detectable in MP recordings (r2 = 0.033, p = 0.484). Audiograms were available at both time points in 97% (n = 38) of all subjects. The mean postoperative hearing loss in the AP group was 13 dB (n = 16, SD = 9). A significantly larger hearing loss was detectable in the MP and AP-MP groups with 28 (n = 17, SD = 10) and 35 dB (n = 6, SD = 13), respectively (AP versus MP p = 0.002, AP versus AP-MP p = 0.002, MP versus AP-MP p = 0.926). CONCLUSION MP and AP-MP response patterns of the electrocochleographic responses along the electrode array after cochlear implantation are correlated with higher four-point impedances and poorer postoperative hearing compared to AP response patterns. The higher impedances suggest that MP and AP-MP patterns are associated with increased intracochlear fibrosis.
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Anfuso CD, Cosentino A, Agafonova A, Zappalà A, Giurdanella G, Trovato Salinaro A, Calabrese V, Lupo G. Pericytes of Stria Vascularis Are Targets of Cisplatin-Induced Ototoxicity: New Insights into the Molecular Mechanisms Involved in Blood-Labyrinth Barrier Breakdown. Int J Mol Sci 2022; 23:ijms232415790. [PMID: 36555432 PMCID: PMC9781621 DOI: 10.3390/ijms232415790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 12/10/2022] [Accepted: 12/11/2022] [Indexed: 12/15/2022] Open
Abstract
The stria vascularis (SV) contributes to cochlear homeostasis and consists of three layers, one of which contains the blood-labyrinthic barrier (BLB), with a large number of bovine cochlear pericytes (BCPs). Cisplatin is a chemotherapeutic drug that can damage the SV and cause hearing loss. In this study, cell viability, proliferation rate, cytotoxicity and reactive oxygen species production were evaluated. The protein content of phospho-extracellular signal-regulated kinases (ERK) 1/2, total ERK 1/2, phospho-cytosolic phospholipase A2 (cPLA2), total cPLA2 and cyclooxygenase 2 (COX-2) and the release of prostaglandin E2 (PGE2) and vascular endothelial growth factor (VEGF) from BCPs were analyzed. Finally, the protective effect of platelet-derived growth factor (PDGF-BB) on BCPs treated with cisplatin was investigated. Cisplatin reduced viability and proliferation, activated ERK 1/2, cPLA2 and COX-2 expression and increased PGE2 and VEGF release; these effects were reversed by Dexamethasone. The presence of PDGF-BB during the treatment with cisplatin significantly increased the proliferation rate. No studies on cell regeneration in ear tissue evaluated the effect of the PDGF/Dex combination. The aim of this study was to investigate the effects of cisplatin on cochlear pericytes and propose new otoprotective agents aimed at preventing the reduction of their vitality and thus maintaining the BLB structure.
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Affiliation(s)
- Carmelina Daniela Anfuso
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, 95123 Catania, Italy
| | - Alessia Cosentino
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, 95123 Catania, Italy
| | - Aleksandra Agafonova
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, 95123 Catania, Italy
| | - Agata Zappalà
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, 95123 Catania, Italy
| | | | - Angela Trovato Salinaro
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, 95123 Catania, Italy
| | - Vittorio Calabrese
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, 95123 Catania, Italy
| | - Gabriella Lupo
- Section of Medical Biochemistry, Department of Biomedical and Biotechnological Sciences, School of Medicine, University of Catania, 95123 Catania, Italy
- Correspondence:
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Gay RD, Enke YL, Kirk JR, Goldman DR. Therapeutics for hearing preservation and improvement of patient outcomes in cochlear implantation—Progress and possibilities. Hear Res 2022; 426:108637. [DOI: 10.1016/j.heares.2022.108637] [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: 12/09/2021] [Revised: 10/11/2022] [Accepted: 10/18/2022] [Indexed: 11/04/2022]
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Razmovski T, Bester C, Collins A, Tan E, O'Leary SJ. Four-Point Impedance Changes After Cochlear Implantation for Lateral Wall and Perimodiolar Implants. Otol Neurotol 2022; 43:e1107-e1114. [PMID: 36351225 DOI: 10.1097/mao.0000000000003732] [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: 11/10/2022]
Abstract
OBJECTIVE Monitor four-point impedance in cochlear implant recipients over time and determine if implant type, surgical approach, and electrode positioning affected impedance measurements. STUDY DESIGN Prospective observational. SETTING Hospital. PATIENTS Adult cochlear implant recipients implanted with a perimodiolar or lateral wall cochlear implant. MAIN OUTCOME MEASURES Mean values for four-point impedances were calculated for all electrode contacts at perioperative and 3 months after surgery. Linear mixed models were applied to the impedance data to compare between implant types and time points. The angular insertion depth and electrode position relative to the medial and lateral wall, commonly termed the Intracochlear Position Index (ICPI), were collected and compared with impedance measurements. RESULTS Perioperatively, the four-point impedance was similar between implant types, with perimodiolar implants having marginally higher impedance values in the basal region. At 3 months after surgery, impedances significantly increased in the basal half of the electrode array for both implants, with higher impedance values for CI532 implants. There were no significant differences in insertion angle depth between implant types. The ICPI values for the seven most basal electrodes were similar for both implants; however, CI532 arrays were significantly more medially placed along the remaining apical portion of the array, which is expected. ICPI values did not correlate with impedance measurements for either implant. CONCLUSIONS Four-point impedance increases at 3 months after surgery may reflect fibrous tissue formation after cochlear implantation. The higher impedance values in perimodiolar implants may reflect a more extensive fibrosis formation as a result of surgical approaches used, requiring drilling of the cochlea bone.
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Affiliation(s)
- Tayla Razmovski
- Department of Surgery (Otolaryngology), The University of Melbourne
| | | | - Aaron Collins
- Department of Surgery (Otolaryngology), The University of Melbourne
| | - Eren Tan
- Department of Surgery (Otolaryngology), The University of Melbourne
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Buswinka CJ, Colesa DJ, Swiderski DL, Raphael Y, Pfingst BE. Components of impedance in a cochlear implant animal model with TGFβ1-accelerated fibrosis. Hear Res 2022; 426:108638. [PMID: 36368194 PMCID: PMC10794021 DOI: 10.1016/j.heares.2022.108638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 09/21/2022] [Accepted: 10/18/2022] [Indexed: 11/04/2022]
Abstract
Outcomes of cochlear implantation are likely influenced by the biological state of the cochlea. Fibrosis is a pathological change frequently seen in implanted ears. The goal of this work was to investigate the relationship between fibrosis and impedance. To that end, we employed an animal model of extensive fibrosis and tested whether aspects of impedance differed from controls. Specifically, an adenovirus with a TGF-β1 gene insert (Ad.TGF-β1) was injected into guinea pig scala tympani to elicit rapid onset fibrosis and investigate the relation between fibrosis and impedance. We found a significant correlation between treatment and rate of impedance increase. A physical circuit model of impedance was used to separate the effect of fibrosis from other confounding factors. Supported by preliminary, yet nonconclusive, electron microscopy data, this modeling suggested that deposits on the electrode surface are an important contributor to impedance change over time.
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Affiliation(s)
- Christopher J Buswinka
- Eaton-Peabody Laboratories, Mass Eye and Ear Hospital and Harvard Medical School, Boston MA 02114.
| | - Deborah J Colesa
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Donald L Swiderski
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Yehoash Raphael
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Bryan E Pfingst
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI, 48109, USA
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Claussen AD, Quevedo RV, Kirk JR, Higgins T, Mostaert B, Rahman MT, Oleson J, Hernandez R, Hirose K, Hansen MR. Chronic cochlear implantation with and without electric stimulation in a mouse model induces robust cochlear influx of CX3CR1 +/GFP macrophages. Hear Res 2022; 426:108510. [PMID: 35527124 PMCID: PMC9596618 DOI: 10.1016/j.heares.2022.108510] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 03/27/2022] [Accepted: 04/23/2022] [Indexed: 12/16/2022]
Abstract
BACKGROUND Cochlear implantation is an effective auditory rehabilitation strategy for those with profound hearing loss, including those with residual low frequency hearing through use of hybrid cochlear implantation techniques. Post-mortem studies demonstrate the nearly ubiquitous presence of intracochlear fibrosis and neo-ossification following cochlear implantation. Current evidence suggests post-implantation intracochlear fibrosis is associated with delayed loss of residual acoustic hearing in hybrid cochlear implant (CI) recipients and may also negatively influence outcomes in traditional CI recipients. This study examined the contributions of surgical trauma, foreign body response and electric stimulation to intracochlear fibrosis and the innate immune response to cochlear implantation and the hierarchy of these contributions. METHODS Normal hearing CX3CR1+/GFP mice underwent either round window opening (sham), acute CI insertion or chronic CI insertion with no, low- or high-level electric stimulation. Electric stimulation levels were based on neural response telemetry (NRT), beginning post-operative day 7 for 5 h per day. Subjects (n=3 per timepoint) were sacrificed at 4 h, 1,4,7,8,11,14 and 21 days. An unoperated group (n=3) served as controls. Cochleae were harvested at each time-point and prepared for immunohistochemistry with confocal imaging. The images were analyzed to obtain CX3CR1+ macrophage cell number and density in the lateral wall (LW), scala tympani (ST) and Rosenthal's canal (RC). RESULTS A ST peri-implant cellular infiltrate and fibrosis occurred exclusively in the chronically implanted groups starting on day 7 with a concurrent infiltration of CX3CR1+ macrophages not seen in the other groups. CX3CR1+ macrophage infiltration was seen in the LW and RC in all experimental groups within the first week, being most prominent in the 3 chronically implanted groups during the second and third week. CONCLUSIONS The cochlear immune response was most prominent in the presence of chronic cochlear implantation, regardless of electric stimulation level. Further, the development of intracochlear ST fibrosis was dependent on the presence of the indwelling CI foreign body. An innate immune response was evoked by surgical trauma alone (sham and acute CI groups) to a lesser degree. These data suggest that cochlear inflammation and intrascalar fibrosis after cochlear implantation are largely dependent on the presence of a chronic indwelling foreign body and are not critically dependent on electrical stimulation. Also, these data support a role for surgical trauma in inciting the initial innate immune response.
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Affiliation(s)
- Alexander D Claussen
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, United States; Department of Otolaryngology Head and Neck Surgery, University of California San Diego, San Diego, CA 92103, United States.
| | - René Vielman Quevedo
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, United States; Department of Biomedical Sciences, Creighton University, Omaha, NE 68178, United States
| | | | - Timon Higgins
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, United States
| | - Brian Mostaert
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, United States
| | - Muhammad Taifur Rahman
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, United States
| | - Jacob Oleson
- Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, IA 52242, United States
| | - Reyna Hernandez
- Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, IA 52242, United States
| | - Keiko Hirose
- Department of Otolaryngology Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO 63110, United States
| | - Marlan R Hansen
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, United States
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Mushtaq F, Soulby A, Boyle P, Nunn T, Hartley DEH. Self-assessment of cochlear health by cochlear implant recipients. Front Neurol 2022; 13:1042408. [DOI: 10.3389/fneur.2022.1042408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 10/25/2022] [Indexed: 11/18/2022] Open
Abstract
Recent technological advances in cochlear implant (CI) telemetry have enabled, for the first time, CI users to perform cochlear health (CH) measurements through self-assessment for prolonged periods of time. This is important to better understand the influence of CH on CI outcomes, and to assess the safety and efficacy of future novel treatments for deafness that will be administered as adjunctive therapies to cochlear implantation. We evaluated the feasibility of using a CI to assess CH and examined patterns of electrode impedances, electrically-evoked compound action potentials (eCAPs) and electrocochleography (ECochGs), over time, in a group of adult CI recipients. Fifteen subjects were trained to use the Active Insertion Monitoring tablet by Advanced Bionics, at home for 12 weeks to independently record impedances twice daily, eCAPs once weekly and ECochGs daily in the first week, and weekly thereafter. Participants also completed behavioral hearing and speech assessments. Group level measurement compliance was 98.9% for impedances, 100% for eCAPs and 99.6% for ECochGs. Electrode impedances remained stable over time, with only minimal variation observed. Morning impedances were significantly higher than evening measurements, and impedances increased toward the base of the cochlea. eCAP thresholds were also highly repeatable, with all subjects showing 100% measurement consistency at, at least one electrode. Just over half of all subjects showed consistently absent thresholds at one or more electrodes, potentially suggesting the existence of cochlear dead regions. All subjects met UK NICE guidelines for cochlear implantation, so were expected to have little residual hearing. ECochG thresholds were, unsurprisingly, highly erratic and did not correlate with audiometric thresholds, though lower ECochG thresholds showed more repeatability over time than higher thresholds. We conclude that it is feasible for CI users to independently record CH measurements using their CI, and electrode impedances and eCAPs are promising measurements for objectively assessing CH.
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Hoffmann JAC, Warnecke A, Timm ME, Kludt E, Prenzler NK, Gärtner L, Lenarz T, Salcher RB. Cochlear Implantation in Obliterated Cochlea: A Retrospective Analysis and Comparison between the IES Stiff Custom-Made Device and the Split-Array and Regular Electrodes. J Clin Med 2022; 11:jcm11206090. [PMID: 36294411 PMCID: PMC9605638 DOI: 10.3390/jcm11206090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 10/12/2022] [Accepted: 10/13/2022] [Indexed: 11/07/2022] Open
Abstract
Anatomical malformations, obliterations of the cochlea, or re-implantations pose particular challenges in cochlear implantation. Treatment methods rely on radiological and intraoperative findings and include incomplete insertion, the implantation of a double array, and radical cochleostomy. In addition, a stiff electrode array, e.g., the IE stiff (IES) custom-made device (CMD, MED-EL), was prescribed individually for those special cases and pre-inserted prior to facilitate cochlear implantation in challenging cases. Data on outcomes after implantation in obliterated cochleae are usually based on individual case reports since standardised procedures are lacking. A retrospective analysis was conducted to analyse our cases on obliterated cochleae treated with MED-EL devices in order to allow the different cases to be compared. Impedances and speech perception data of patients treated with the IES CMD and the double array were retrospectively compared to patients treated with a STANDARD or FLEX electrode array (the REGULAR group). Patients with a Split-Array CMD had a poor speech perception when compared to patients treated with the IES CMD device. Thus, the IES CMD can successfully be used in patients with obliterated cochleae who would otherwise be non-users, candidates for a Split-Array CMD, or candidates for partial insertion with insufficient cochlear coverage.
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Affiliation(s)
| | - Athanasia Warnecke
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medial School, 30625 Hannover, Germany
- Cluster of Excellence “Hearing4all”, Hannover Medical School, 30625 Hannover, Germany
| | - Max Eike Timm
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medial School, 30625 Hannover, Germany
- Cluster of Excellence “Hearing4all”, Hannover Medical School, 30625 Hannover, Germany
| | - Eugen Kludt
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medial School, 30625 Hannover, Germany
- Cluster of Excellence “Hearing4all”, Hannover Medical School, 30625 Hannover, Germany
| | - Nils Kristian Prenzler
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medial School, 30625 Hannover, Germany
- Cluster of Excellence “Hearing4all”, Hannover Medical School, 30625 Hannover, Germany
| | - Lutz Gärtner
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medial School, 30625 Hannover, Germany
- Cluster of Excellence “Hearing4all”, Hannover Medical School, 30625 Hannover, Germany
| | - Thomas Lenarz
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medial School, 30625 Hannover, Germany
- Cluster of Excellence “Hearing4all”, Hannover Medical School, 30625 Hannover, Germany
| | - Rolf Benedikt Salcher
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medial School, 30625 Hannover, Germany
- Cluster of Excellence “Hearing4all”, Hannover Medical School, 30625 Hannover, Germany
- Correspondence:
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Reiss LA, Kirk J, Claussen AD, Fallon JB. Animal Models of Hearing Loss after Cochlear Implantation and Electrical Stimulation. Hear Res 2022; 426:108624. [DOI: 10.1016/j.heares.2022.108624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 03/28/2022] [Accepted: 09/23/2022] [Indexed: 11/04/2022]
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Rahman MT, Chari DA, Ishiyama G, Lopez I, Quesnel AM, Ishiyama A, Nadol JB, Hansen MR. Cochlear implants: Causes, effects and mitigation strategies for the foreign body response and inflammation. Hear Res 2022; 422:108536. [PMID: 35709579 PMCID: PMC9684357 DOI: 10.1016/j.heares.2022.108536] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 04/20/2022] [Accepted: 05/23/2022] [Indexed: 12/15/2022]
Abstract
Cochlear implants provide effective auditory rehabilitation for patients with severe to profound sensorineural hearing loss. Recent advances in cochlear implant technology and surgical approaches have enabled a greater number of patients to benefit from this technology, including those with significant residual low frequency acoustic hearing. Nearly all cochleae implanted with a cochlear implant electrode array develop an inflammatory and fibrotic response. This tissue reaction can have deleterious consequences for implant function, residual acoustic hearing, and the development of the next generation of cochlear prosthetics. This article reviews the current understanding of the inflammatory/foreign body response (FBR) after cochlear implant surgery, its impact on clinical outcome, and therapeutic strategies to mitigate this response. Findings from both in human subjects and animal models across a variety of species are highlighted. Electrode array design, surgical techniques, implant materials, and the degree and type of electrical stimulation are some critical factors that affect the FBR and inflammation. Modification of these factors and various anti-inflammatory pharmacological interventions have been shown to mitigate the inflammatory/FBR response. Ongoing and future approaches that seek to limit surgical trauma and curb the FBR to the implanted biomaterials of the electrode array are discussed. A better understanding of the anatomical, cellular and molecular basis of the inflammatory/FBR response after cochlear implantation has the potential to improve the outcome of current cochlear implants and also facilitate the development of the next generation of neural prostheses.
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Affiliation(s)
- Muhammad T Rahman
- Department of Otolaryngology-Head & Neck Surgery, University of Iowa, Iowa City, IA, USA
| | - Divya A Chari
- Department of Otolaryngology-Head & Neck Surgery, Harvard University, Boston, MA, USA
| | - Gail Ishiyama
- Department of Head & Neck Surgery, University of California Los Angeles, LA, USA
| | - Ivan Lopez
- Department of Head & Neck Surgery, University of California Los Angeles, LA, USA
| | - Alicia M Quesnel
- Department of Otolaryngology-Head & Neck Surgery, Harvard University, Boston, MA, USA
| | - Akira Ishiyama
- Department of Head & Neck Surgery, University of California Los Angeles, LA, USA
| | - Joseph B Nadol
- Department of Otolaryngology-Head & Neck Surgery, Harvard University, Boston, MA, USA
| | - Marlan R Hansen
- Department of Otolaryngology-Head & Neck Surgery, University of Iowa, Iowa City, IA, USA.
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Guimier E, Carson L, David B, Lambert JM, Heery E, Malcolm RK. Pharmacological Approaches for the Prevention of Breast Implant Capsular Contracture. J Surg Res 2022; 280:129-150. [PMID: 35969932 DOI: 10.1016/j.jss.2022.06.073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 06/17/2022] [Accepted: 06/29/2022] [Indexed: 11/15/2022]
Abstract
Capsular contracture is a common complication associated with breast implants following reconstructive or aesthetic surgery in which a tight or constricting scar tissue capsule forms around the implant, often distorting the breast shape and resulting in chronic pain. Capsulectomy (involving full removal of the capsule surrounding the implant) and capsulotomy (where the capsule is released and/or partly removed to create more space for the implant) are the most common surgical procedures used to treat capsular contracture. Various structural modifications of the implant device (including use of textured implants, submuscular placement of the implant, and the use of polyurethane-coated implants) and surgical strategies (including pre-operative skin washing and irrigation of the implant pocket with antibiotics) have been and/or are currently used to help reduce the incidence of capsular contracture. In this article, we review the pharmacological approaches-both commonly practiced in the clinic and experimental-reported in the scientific and clinical literature aimed at either preventing or treating capsular contracture, including (i) pre- and post-operative intravenous administration of drug substances, (ii) systemic (usually oral) administration of drugs before and after surgery, (iii) modification of the implant surface with grafted drug substances, (iv) irrigation of the implant or peri-implant tissue with drugs prior to implantation, and (v) incorporation of drugs into the implant shell or filler prior to surgery followed by drug release in situ after implantation.
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Affiliation(s)
| | - Louise Carson
- School of Pharmacy, Queen's University Belfast, Belfast, UK
| | - Benny David
- NuSil Technology LLC, Carpinteria, California
| | | | | | - R Karl Malcolm
- School of Pharmacy, Queen's University Belfast, Belfast, UK.
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Four-point Impedance Changes in the Early Post-Operative Period After Cochlear Implantation. Otol Neurotol 2022; 43:e730-e737. [PMID: 35861642 DOI: 10.1097/mao.0000000000003592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Monitoring four-point impedance changes after cochlear implantation with comparison to conventional impedance measurements. Four-point impedance provides information regarding the bulk biological environment surrounding the electrode array, which is not discernible with conventional impedances. STUDY DESIGN Prospective observational. SETTING Hospital. PATIENTS Adult cochlear implant recipients with no measurable hearing before implantation and implanted with a perimodiolar cochlear implant. MAIN OUTCOME MEASURES Mean values for four-point and common ground impedances were calculated for all electrode contacts at intra-operative, 1 day, 1 week, 4 to 6 weeks, and 3 months post implantation. Linear mixed models were applied to the impedance data to compare between impedances and time points. Furthermore, patients were divided into groups dependent on the normalized change in four-point impedance from intra-operative to 1 day post-operative. The normalized change was then calculated for all other time points and compared across the two groups. RESULTS Significant increases in four-point impedance occurred 1 day and 3 months after surgery, particularly in the basal half of the array. Four-point impedance at 1 day was highly predictive of four-point impedance at 3 months. Four-point impedance at the other time points showed marginal or no increases from intra-operative. Patients with an average increase higher than 10% in four-point impedance from intra-operative to 1 day, had significantly higher values at 3 months ( p = 0.012). These patterns were not observed in common ground impedance. CONCLUSION This is the first study to report increases in four-point impedance within 24 hours of cochlear implantation. The increases at 1 day and 3 months align with the natural timeline of an acute and chronic inflammatory responses.
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Khurana L, Keppeler D, Jablonski L, Moser T. Model-based prediction of optogenetic sound encoding in the human cochlea by future optical cochlear implants. Comput Struct Biotechnol J 2022; 20:3621-3629. [PMID: 35860414 PMCID: PMC9283772 DOI: 10.1016/j.csbj.2022.06.061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/28/2022] [Accepted: 06/28/2022] [Indexed: 01/17/2023] Open
Abstract
When hearing fails, electrical cochlear implants (eCIs) partially restore hearing by direct stimulation of spiral ganglion neurons (SGNs). As light can be better confined in space than electrical current, optical CIs (oCIs) provide more spectral information promising a fundamental improvement of hearing restoration by cochlear implants. Here, we turned to computer modelling for predicting the outcome of optogenetic hearing restoration by future oCIs in humans. We combined three-dimensional reconstruction of the human cochlea with ray-tracing simulation of emission from LED or laser-coupled waveguide emitters of the oCI. Irradiance was read out at the somata of SGNs. The irradiance values reached with waveguides were about 14 times higher than with LEDs, at the same radiant flux of the emitter. Moreover, waveguides outperformed LEDs regarding spectral selectivity. oCIs with either emitter type showed greater spectral selectivity when compared to eCI. In addition, modeling the effects of the source-to-SGN distance, orientation of the sources and impact of scar tissue further informs the development of optogenetic hearing restoration.
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Affiliation(s)
- Lakshay Khurana
- Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany.,Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany.,Auditory Neuroscience & Synaptic Nanophysiology Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.,Göttingen Graduate Center for Neurosciences, Biophysics, and Molecular Biosciences (GGNB), University of Göttingen, Göttingen, Germany.,InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Daniel Keppeler
- Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany.,Auditory Neuroscience & Synaptic Nanophysiology Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.,InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Lukasz Jablonski
- Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany.,Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany.,InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany.,Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, Göttingen, Germany.,Auditory Neuroscience & Synaptic Nanophysiology Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.,InnerEarLab, University Medical Center Göttingen, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
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44
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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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Matin-Mann F, Gao Z, Schwieger J, Ulbricht M, Domsta V, Senekowitsch S, Weitschies W, Seidlitz A, Doll K, Stiesch M, Lenarz T, Scheper V. Individualized, Additively Manufactured Drug-Releasing External Ear Canal Implant for Prevention of Postoperative Restenosis: Development, In Vitro Testing, and Proof of Concept in an Individual Curative Trial. Pharmaceutics 2022; 14:pharmaceutics14061242. [PMID: 35745813 PMCID: PMC9228097 DOI: 10.3390/pharmaceutics14061242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 06/08/2022] [Accepted: 06/09/2022] [Indexed: 11/16/2022] Open
Abstract
Postoperative restenosis in patients with external ear canal (EEC) atresia or stenosis is a common complication following canaloplasty. Our aim in this study was to explore the feasibility of using a three dimensionally (3D)-printed, patient-individualized, drug ((dexamethasone (DEX)), and ciprofloxacin (cipro))-releasing external ear canal implant (EECI) as a postoperative stent after canaloplasty. We designed and pre-clinically tested this novel implant for drug release (by high-performance liquid chromatography), biocompatibility (by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay), bio-efficacy (by the TNF-α (tumor necrosis factor-alpha)-reduction test (DEX) and inhibition zone test (for cipro)), and microbial contamination (formation of turbidity or sediments in culture medium). The EECI was implanted for the first time to one patient with a history of congenital EEC atresia and state after three canaloplasties due to EEC restenosis. The preclinical tests revealed no cytotoxic effect of the used materials; an antibacterial effect was verified against the bacteria Staphylococcus aureus and Pseudomonas aeruginosa, and the tested UV-irradiated EECI showed no microbiological contamination. Based on the test results, the combination of silicone with 1% DEX and 0.3% cipro was chosen to treat the patient. The EECI was implantable into the EEC; the postoperative follow-up visits revealed no otogenic symptoms or infections and the EECI was explanted three months postoperatively. Even at 12 months postoperatively, the EEC showed good epithelialization and patency. Here, we report the first ever clinical application of an individualized, drug-releasing, mechanically flexible implant and suggest that our novel EECI represents a safe and effective method for postoperatively stenting the reconstructed EEC.
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Affiliation(s)
- Farnaz Matin-Mann
- Department of Otorhinolaryngology, Head and Neck Surgery, Lower Saxony Center for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Stadtfelddamm 34, 30625 Hannover, Germany; (Z.G.); (J.S.); (T.L.); (V.S.)
- Correspondence: ; Tel.: +49-511-532-6565; Fax: +49-511-532-8001
| | - Ziwen Gao
- Department of Otorhinolaryngology, Head and Neck Surgery, Lower Saxony Center for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Stadtfelddamm 34, 30625 Hannover, Germany; (Z.G.); (J.S.); (T.L.); (V.S.)
- Cluster of Excellence”Hearing4all” EXC 1077/1, 30625 Hannover, Germany
| | - Jana Schwieger
- Department of Otorhinolaryngology, Head and Neck Surgery, Lower Saxony Center for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Stadtfelddamm 34, 30625 Hannover, Germany; (Z.G.); (J.S.); (T.L.); (V.S.)
- Cluster of Excellence”Hearing4all” EXC 1077/1, 30625 Hannover, Germany
| | - Martin Ulbricht
- Center of Drug Absorption and Transport, Department of Biopharmacy and Pharmaceutical Technology, Institute of Pharmacy, University of Greifswald, 17489 Greifswald, Germany; (M.U.); (V.D.); (S.S.); (W.W.); (A.S.)
| | - Vanessa Domsta
- Center of Drug Absorption and Transport, Department of Biopharmacy and Pharmaceutical Technology, Institute of Pharmacy, University of Greifswald, 17489 Greifswald, Germany; (M.U.); (V.D.); (S.S.); (W.W.); (A.S.)
| | - Stefan Senekowitsch
- Center of Drug Absorption and Transport, Department of Biopharmacy and Pharmaceutical Technology, Institute of Pharmacy, University of Greifswald, 17489 Greifswald, Germany; (M.U.); (V.D.); (S.S.); (W.W.); (A.S.)
| | - Werner Weitschies
- Center of Drug Absorption and Transport, Department of Biopharmacy and Pharmaceutical Technology, Institute of Pharmacy, University of Greifswald, 17489 Greifswald, Germany; (M.U.); (V.D.); (S.S.); (W.W.); (A.S.)
| | - Anne Seidlitz
- Center of Drug Absorption and Transport, Department of Biopharmacy and Pharmaceutical Technology, Institute of Pharmacy, University of Greifswald, 17489 Greifswald, Germany; (M.U.); (V.D.); (S.S.); (W.W.); (A.S.)
- Institute of Pharmaceutics and Biopharmaceutics, University of Duesseldorf, 40225 Dusseldorf, Germany
| | - Katharina Doll
- Clinic for Dental Prosthetics and Biomedical Materials Science, Hanover Medical School, 30625 Hannover, Germany; (K.D.); (M.S.)
| | - Meike Stiesch
- Clinic for Dental Prosthetics and Biomedical Materials Science, Hanover Medical School, 30625 Hannover, Germany; (K.D.); (M.S.)
| | - Thomas Lenarz
- Department of Otorhinolaryngology, Head and Neck Surgery, Lower Saxony Center for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Stadtfelddamm 34, 30625 Hannover, Germany; (Z.G.); (J.S.); (T.L.); (V.S.)
- Cluster of Excellence”Hearing4all” EXC 1077/1, 30625 Hannover, Germany
| | - Verena Scheper
- Department of Otorhinolaryngology, Head and Neck Surgery, Lower Saxony Center for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Stadtfelddamm 34, 30625 Hannover, Germany; (Z.G.); (J.S.); (T.L.); (V.S.)
- Cluster of Excellence”Hearing4all” EXC 1077/1, 30625 Hannover, Germany
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Biological Response Dynamics to Cochlear Implantation: Modeling and Modulating the Electrode–Tissue Interface. Ear Hear 2022; 43:1687-1697. [DOI: 10.1097/aud.0000000000001236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Leblans M, Sismono F, Vanpoucke F, van Dinther J, Lerut B, Kuhweide R, Offeciers E, Zarowski A. Novel Impedance Measures as Biomarker for Intracochlear Fibrosis. Hear Res 2022; 426:108563. [DOI: 10.1016/j.heares.2022.108563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 04/05/2022] [Accepted: 06/15/2022] [Indexed: 11/04/2022]
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48
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Liu SS, Yang R. Inner Ear Drug Delivery for Sensorineural Hearing Loss: Current Challenges and Opportunities. Front Neurosci 2022; 16:867453. [PMID: 35685768 PMCID: PMC9170894 DOI: 10.3389/fnins.2022.867453] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 05/02/2022] [Indexed: 12/20/2022] Open
Abstract
Most therapies for treating sensorineural hearing loss are challenged by the delivery across multiple tissue barriers to the hard-to-access anatomical location of the inner ear. In this review, we will provide a recent update on various pharmacotherapy, gene therapy, and cell therapy approaches used in clinical and preclinical studies for the treatment of sensorineural hearing loss and approaches taken to overcome the drug delivery barriers in the ear. Small-molecule drugs for pharmacotherapy can be delivered via systemic or local delivery, where the blood-labyrinth barrier hinders the former and tissue barriers including the tympanic membrane, the round window membrane, and/or the oval window hinder the latter. Meanwhile, gene and cell therapies often require targeted delivery to the cochlea, which is currently achieved via intra-cochlear or intra-labyrinthine injection. To improve the stability of the biomacromolecules during treatment, e.g., RNAs, DNAs, proteins, additional packing vehicles are often required. To address the diverse range of biological barriers involved in inner ear drug delivery, each class of therapy and the intended therapeutic cargoes will be discussed in this review, in the context of delivery routes commonly used, delivery vehicles if required (e.g., viral and non-viral nanocarriers), and other strategies to improve drug permeation and sustained release (e.g., hydrogel, nanocarriers, permeation enhancers, and microfluidic systems). Overall, this review aims to capture the important advancements and key steps in the development of inner ear therapies and delivery strategies over the past two decades for the treatment and prophylaxis of sensorineural hearing loss.
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Affiliation(s)
- Sophie S. Liu
- Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, United States
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, United States
| | - Rong Yang
- Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, United States
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, United States
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Brotto D, Caserta E, Sorrentino F, Favaretto N, Marioni G, Martini A, Bovo R, Gheller F, Trevisi P. Long-Term Impedance Trend in Cochlear Implant Users with Genetically Determined Congenital Profound Hearing Loss. J Am Acad Audiol 2022; 33:105-114. [PMID: 35577055 DOI: 10.1055/s-0041-1739290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND Impedance is a basic parameter registered at any cochlear implant (CI) fitting section. It is useful in monitoring electrode functioning and the status of the surrounding anatomical structures. PURPOSE The main aim of this study is to evaluate the 5-year impedance-value trend in patients affected by congenital genetically determined profound hearing loss implanted with Cochlear Nucleus devices. RESEARCH DESIGN Observational, retrospective, monocentric study. STUDY SAMPLE Twenty-seven consecutive patients (9 females: 12.0 ± 7.6 years old; range: 4.2-40.4) with genetic diagnosis of GJB2 mutation causing congenital profound hearing loss who underwent cochlear implantation from 2010 to 2020 with good auditory benefit. INTERVENTION Impedance values of the CIs were obtained from the CIs' programming software that registers those parameters for each follow-up section of each patient. DATA COLLECTION AND ANALYSIS Impedance values were measured over time (activation, 6, 12, 24, and 60 months after cochlear implantation), for each of the 22 electrodes, in common ground, monopolar 1, monopolar 2, and monopolar 1 + 2 stimulation modes. RESULTS A significant variation was found between CI activation and 6-month follow-up. This difference was found for each of the 22 electrodes. Electrodes 1 to 4 showed higher impedance values compared with all other electrodes in each time interval. Repeated-measures analysis of variance ruled out significant variations in impedance values from 6-month to 5-year follow-up. CONCLUSIONS Impedance values were extremely stable after activation, at least for the first 5 years. In these cases, even minimal impedance variations should be carefully evaluated for their possible implications on hearing performance.
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Affiliation(s)
- Davide Brotto
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Ezio Caserta
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Flavia Sorrentino
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Niccolò Favaretto
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Gino Marioni
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Alessandro Martini
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Roberto Bovo
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Flavia Gheller
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
| | - Patrizia Trevisi
- Section of Otorhinolaryngology - Head and Neck Surgery, Department of Neurosciences, University of Padova, Padova, Italy
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Schwieger J, Frisch AS, Rau TS, Lenarz T, Hügl S, Scheper V. 3D Printed Cell Culture Chamber for Testing the Effect of Pump-Based Chronic Drug Delivery on Inner Ear Tissue. Biomolecules 2022; 12:biom12040589. [PMID: 35454178 PMCID: PMC9032916 DOI: 10.3390/biom12040589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/11/2022] [Accepted: 04/15/2022] [Indexed: 11/16/2022] Open
Abstract
Cochlear hair cell damage and spiral ganglion neuron (SGN) degeneration are the main causes of sensory neural hearing loss. Cochlear implants (CIs) can replace the function of the hair cells and stimulate the SGNs electrically. The condition of the SGNs and their spatial distance to the CI are key factors for CI-functionality. For a better performance, a high number of neurons and a closer contact to the electrode are intended. Neurotrophic factors are able to enhance SGN survival and neurite outgrowth, and thereby might optimize the electrode-nerve interaction. This would require chronic factor treatment, which is not yet established for the inner ear. Investigations on chronic drug delivery to SGNs could benefit from an appropriate in vitro model. Thus, an inner ear inspired Neurite Outgrowth Chamber (NOC), which allows the incorporation of a mini-osmotic pump for long-term drug delivery, was designed and three-dimensionally printed. The NOC’s function was validated using spiral ganglion explants treated with ciliary neurotrophic factor, neurotrophin-3, or control fluid released via pumps over two weeks. The NOC proved to be suitable for explant cultivation and observation of pump-based drug delivery over the examined period, with neurotrophin-3 significantly increasing neurite outgrowth compared to the other groups.
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Affiliation(s)
- Jana Schwieger
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, 30625 Hannover, Germany; (A.S.F.); (T.S.R.); (T.L.); (S.H.); (V.S.)
- Lower Saxony Center for Biomedical Engineering, Implant Research and Development (NIFE), Stadtfelddamm 34, 30625 Hannover, Germany
- Cluster of Excellence “Hearing4all” EXC 1077/2, 30625 Hannover, Germany
- Correspondence: ; Tel.: +49-5115327262
| | - Anna Sophie Frisch
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, 30625 Hannover, Germany; (A.S.F.); (T.S.R.); (T.L.); (S.H.); (V.S.)
- Lower Saxony Center for Biomedical Engineering, Implant Research and Development (NIFE), Stadtfelddamm 34, 30625 Hannover, Germany
| | - Thomas S. Rau
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, 30625 Hannover, Germany; (A.S.F.); (T.S.R.); (T.L.); (S.H.); (V.S.)
- Lower Saxony Center for Biomedical Engineering, Implant Research and Development (NIFE), Stadtfelddamm 34, 30625 Hannover, Germany
- Cluster of Excellence “Hearing4all” EXC 1077/2, 30625 Hannover, Germany
| | - Thomas Lenarz
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, 30625 Hannover, Germany; (A.S.F.); (T.S.R.); (T.L.); (S.H.); (V.S.)
- Lower Saxony Center for Biomedical Engineering, Implant Research and Development (NIFE), Stadtfelddamm 34, 30625 Hannover, Germany
- Cluster of Excellence “Hearing4all” EXC 1077/2, 30625 Hannover, Germany
| | - Silke Hügl
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, 30625 Hannover, Germany; (A.S.F.); (T.S.R.); (T.L.); (S.H.); (V.S.)
- Lower Saxony Center for Biomedical Engineering, Implant Research and Development (NIFE), Stadtfelddamm 34, 30625 Hannover, Germany
- Cluster of Excellence “Hearing4all” EXC 1077/2, 30625 Hannover, Germany
| | - Verena Scheper
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, 30625 Hannover, Germany; (A.S.F.); (T.S.R.); (T.L.); (S.H.); (V.S.)
- Lower Saxony Center for Biomedical Engineering, Implant Research and Development (NIFE), Stadtfelddamm 34, 30625 Hannover, Germany
- Cluster of Excellence “Hearing4all” EXC 1077/2, 30625 Hannover, Germany
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