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Hrncirik F, Roberts I, Sevgili I, Swords C, Bance M. Models of Cochlea Used in Cochlear Implant Research: A Review. Ann Biomed Eng 2023; 51:1390-1407. [PMID: 37087541 PMCID: PMC10264527 DOI: 10.1007/s10439-023-03192-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 03/20/2023] [Indexed: 04/24/2023]
Abstract
As the first clinically translated machine-neural interface, cochlear implants (CI) have demonstrated much success in providing hearing to those with severe to profound hearing loss. Despite their clinical effectiveness, key drawbacks such as hearing damage, partly from insertion forces that arise during implantation, and current spread, which limits focussing ability, prevent wider CI eligibility. In this review, we provide an overview of the anatomical and physical properties of the cochlea as a resource to aid the development of accurate models to improve future CI treatments. We highlight the advancements in the development of various physical, animal, tissue engineering, and computational models of the cochlea and the need for such models, challenges in their use, and a perspective on their future directions.
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Affiliation(s)
- Filip Hrncirik
- Cambridge Hearing Group, Cambridge, UK.
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0QQ, UK.
| | - Iwan Roberts
- Cambridge Hearing Group, Cambridge, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - Ilkem Sevgili
- Cambridge Hearing Group, Cambridge, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - Chloe Swords
- Cambridge Hearing Group, Cambridge, UK
- Department of Physiology, Development and Neurosciences, University of Cambridge, Cambridge, CB2 3DY, UK
| | - Manohar Bance
- Cambridge Hearing Group, Cambridge, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0QQ, UK
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2
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Glennon E, Valtcheva S, Zhu A, Wadghiri YZ, Svirsky MA, Froemke RC. Locus coeruleus activity improves cochlear implant performance. Nature 2023; 613:317-323. [PMID: 36544024 PMCID: PMC10681749 DOI: 10.1038/s41586-022-05554-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 11/10/2022] [Indexed: 12/24/2022]
Abstract
Cochlear implants (CIs) are neuroprosthetic devices that can provide hearing to deaf people1. Despite the benefits offered by CIs, the time taken for hearing to be restored and perceptual accuracy after long-term CI use remain highly variable2,3. CI use is believed to require neuroplasticity in the central auditory system, and differential engagement of neuroplastic mechanisms might contribute to the variability in outcomes4-7. Despite extensive studies on how CIs activate the auditory system4,8-12, the understanding of CI-related neuroplasticity remains limited. One potent factor enabling plasticity is the neuromodulator noradrenaline from the brainstem locus coeruleus (LC). Here we examine behavioural responses and neural activity in LC and auditory cortex of deafened rats fitted with multi-channel CIs. The rats were trained on a reward-based auditory task, and showed considerable individual differences of learning rates and maximum performance. LC photometry predicted when CI subjects began responding to sounds and longer-term perceptual accuracy. Optogenetic LC stimulation produced faster learning and higher long-term accuracy. Auditory cortical responses to CI stimulation reflected behavioural performance, with enhanced responses to rewarded stimuli and decreased distinction between unrewarded stimuli. Adequate engagement of central neuromodulatory systems is thus a potential clinically relevant target for optimizing neuroprosthetic device use.
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Affiliation(s)
- Erin Glennon
- Skirball Institute for Biomolecular Medicine, New York University School of Medicine, New York, NY, USA
- Neuroscience Institute, New York University School of Medicine, New York, NY, USA
- Department of Otolaryngology, New York University School of Medicine, New York, NY, USA
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA
| | - Silvana Valtcheva
- Skirball Institute for Biomolecular Medicine, New York University School of Medicine, New York, NY, USA
- Neuroscience Institute, New York University School of Medicine, New York, NY, USA
- Department of Otolaryngology, New York University School of Medicine, New York, NY, USA
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA
| | - Angela Zhu
- Skirball Institute for Biomolecular Medicine, New York University School of Medicine, New York, NY, USA
- Neuroscience Institute, New York University School of Medicine, New York, NY, USA
- Department of Otolaryngology, New York University School of Medicine, New York, NY, USA
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA
| | - Youssef Z Wadghiri
- Center for Advanced Imaging Innovation and Research, Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA
| | - Mario A Svirsky
- Neuroscience Institute, New York University School of Medicine, New York, NY, USA.
- Department of Otolaryngology, New York University School of Medicine, New York, NY, USA.
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA.
| | - Robert C Froemke
- Skirball Institute for Biomolecular Medicine, New York University School of Medicine, New York, NY, USA.
- Neuroscience Institute, New York University School of Medicine, New York, NY, USA.
- Department of Otolaryngology, New York University School of Medicine, New York, NY, USA.
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA.
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3
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Sunwoo W, Oh SH. Effects of place of stimulation on the interaural time difference sensitivity in bilateral electrical intracochlear stimulations: Neurophysiological study in a rat model. J Neurosci Res 2021; 100:461-476. [PMID: 34837408 DOI: 10.1002/jnr.24991] [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: 05/06/2021] [Revised: 10/18/2021] [Accepted: 10/23/2021] [Indexed: 11/09/2022]
Abstract
We examined the sensitivity of the neurons in the inferior colliculus (IC) in male and female rats to the interaural time differences (ITDs) conveyed in electrical pulse trains. Using bipolar pairs of electrodes that selectively activate the auditory nerve fibers at different intracochlear locations, we assessed whether the responses to electrical stimulation with ITDs in different frequency regions were processed differently. Most well-isolated single units responded to the electrical stimulation in only one of the apical or basal cochlear regions, and they were classified as either apical or basal units. Regardless of the cochlear stimulating location, more than 70% of both apical and basal units were sensitive to ITDs of electrical stimulation. However, the pulse rate dependence of neural ITD sensitivity differed significantly depending on the location of the stimulation. Moreover, ITD discrimination thresholds and the relative incidence of ITD tuning type markedly differed between units activated by apical and basal stimulations. With apical stimulation, IC neurons had a higher incidence of peak-type ITD function, which mostly exhibited the steepest position of the tuning curve within the rat's physiological ITD range of ±160 μs and, accordingly, had better ITD discrimination thresholds than those with basal stimulation. These results support the idea that ITD processing in the IC might be determined by functionally segregated frequency-specific pathways from the cochlea to the auditory midbrain.
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Affiliation(s)
- Woongsang Sunwoo
- Department of Otorhinolaryngology, Gil Medical Center, Gachon University College of Medicine, Incheon, Republic of Korea
| | - Seung-Ha Oh
- Department of Otorhinolaryngology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea
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Keppeler D, Kampshoff CA, Thirumalai A, Duque-Afonso CJ, Schaeper JJ, Quilitz T, Töpperwien M, Vogl C, Hessler R, Meyer A, Salditt T, Moser T. Multiscale photonic imaging of the native and implanted cochlea. Proc Natl Acad Sci U S A 2021; 118:e2014472118. [PMID: 33903231 PMCID: PMC8106341 DOI: 10.1073/pnas.2014472118] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The cochlea of our auditory system is an intricate structure deeply embedded in the temporal bone. Compared with other sensory organs such as the eye, the cochlea has remained poorly accessible for investigation, for example, by imaging. This limitation also concerns the further development of technology for restoring hearing in the case of cochlear dysfunction, which requires quantitative information on spatial dimensions and the sensorineural status of the cochlea. Here, we employed X-ray phase-contrast tomography and light-sheet fluorescence microscopy and their combination for multiscale and multimodal imaging of cochlear morphology in species that serve as established animal models for auditory research. We provide a systematic reference for morphological parameters relevant for cochlear implant development for rodent and nonhuman primate models. We simulate the spread of light from the emitters of the optical implants within the reconstructed nonhuman primate cochlea, which indicates a spatially narrow optogenetic excitation of spiral ganglion neurons.
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Affiliation(s)
- Daniel Keppeler
- Institute for Auditory Neuroscience, University Medical Center Göttingen, 37075 Göttingen, Germany
- InnerEarLab, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Christoph A Kampshoff
- Institute for Auditory Neuroscience, University Medical Center Göttingen, 37075 Göttingen, Germany
- InnerEarLab, University Medical Center Göttingen, 37075 Göttingen, Germany
- Department of Otolaryngology, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Anupriya Thirumalai
- Institute for Auditory Neuroscience, University Medical Center Göttingen, 37075 Göttingen, Germany
- InnerEarLab, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Carlos J Duque-Afonso
- Institute for Auditory Neuroscience, University Medical Center Göttingen, 37075 Göttingen, Germany
- InnerEarLab, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Jannis J Schaeper
- Institute for X-ray Physics, University of Göttingen, 37075 Göttingen, Germany
| | - Tabea Quilitz
- Institute for Auditory Neuroscience, University Medical Center Göttingen, 37075 Göttingen, Germany
- InnerEarLab, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Mareike Töpperwien
- Institute for X-ray Physics, University of Göttingen, 37075 Göttingen, Germany
| | - Christian Vogl
- Institute for Auditory Neuroscience, University Medical Center Göttingen, 37075 Göttingen, Germany
- InnerEarLab, University Medical Center Göttingen, 37075 Göttingen, Germany
| | | | - Alexander Meyer
- InnerEarLab, University Medical Center Göttingen, 37075 Göttingen, Germany
- Department of Otolaryngology, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Tim Salditt
- Institute for X-ray Physics, University of Göttingen, 37075 Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells," University of Göttingen, 37075 Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience, University Medical Center Göttingen, 37075 Göttingen, Germany;
- InnerEarLab, University Medical Center Göttingen, 37075 Göttingen, Germany
- Department of Otolaryngology, University Medical Center Göttingen, 37075 Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells," University of Göttingen, 37075 Göttingen, Germany
- Auditory Neuroscience and Optogenetics Laboratory, German Primate Center, 37075 Göttingen, Germany
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Dalrymple AN, Huynh M, Nayagam BA, Lee CD, Weiland GR, Petrossians A, J J, Iii W, Fallon JB, Shepherd RK. Electrochemical and biological characterization of thin-film platinum-iridium alloy electrode coatings: a chronic in vivo study. J Neural Eng 2020; 17:036012. [PMID: 32408281 DOI: 10.1088/1741-2552/ab933d] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
OBJECTIVE To evaluate the electrochemical properties, biological response, and surface characterization of an electrodeposited Platinum-Iridium (Pt-Ir) electrode coating on cochlear implants subjected to chronic stimulation in vivo. APPROACH Electrochemical impedance spectroscopy (EIS), charge storage capacity (CSC), charge injection limit (CIL), and voltage transient (VT) impedance were measured bench-top before and after implant and in vivo. Coated Pt-Ir and uncoated Pt electrode arrays were implanted into cochlea of normal hearing rats and stimulated for ∼4 h d, 5 d week-1 for 5 weeks at levels within the normal clinical range. Neural function was monitored using electrically-evoked auditory brainstem responses. After explant, the electrode surfaces were assessed, and cochleae examined histologically. MAIN RESULTS When measured on bench-top before and after stimulation, Pt-Ir coated electrodes had significantly lower VT impedance (p < 0.001) and significantly higher CSC (p < 0.001) and CIL (p < 0.001) compared to uncoated Pt electrodes. In vivo, the CSC and CIL of Pt-Ir were significantly higher than Pt throughout the implantation period (p= 0.047 and p< 0.001, respectively); however, the VT impedance (p= 0.3) was not. There was no difference in foreign body response between material cohorts, although cochleae implanted with coated electrodes contained small deposits of Pt-Ir. There was no evidence of increased neural loss or loss of neural function in either group. Surface examination revealed no Pt corrosion on any electrodes. SIGNIFICANCE Electrodeposited Pt-Ir electrodes demonstrated significant improvements in electrochemical performance on the bench-top and in vivo compared to uncoated Pt. Neural function and tissue response to Pt-Ir electrodes were not different from uncoated Pt, despite small deposits of Pt-Ir in the tissue capsule. Electrodeposited Pt-Ir coatings offer promise as an improved electrode coating for active neural prostheses.
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Dalrymple AN, Robles UA, Huynh M, Nayagam BA, Green RA, Poole-Warren LA, Fallon JB, Shepherd RK. Electrochemical and biological performance of chronically stimulated conductive hydrogel electrodes. J Neural Eng 2020; 17:026018. [DOI: 10.1088/1741-2552/ab7cfc] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Dkhar B, Bhatia A, Saikia PP, Pyngrope H. Improved postauricular surgical approach to the round window of rats. J Neurosci Methods 2020; 330:108481. [PMID: 31669291 DOI: 10.1016/j.jneumeth.2019.108481] [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: 12/21/2018] [Revised: 10/21/2019] [Accepted: 10/22/2019] [Indexed: 10/25/2022]
Abstract
OBJECTIVES Research using rat as an in-vivo model has played an important role in otological research. The rat ear anatomy has been described; however, detailed surgical procedures to access the temporal bone are limited. The authors present a technique to approach the inner ear of rat that was standardized by cadaveric dissections and later replicated in living animals. METHODS Adult Wistar albino rats were dissected via the post-auricular approach. The emphasis was on early identification of the facial nerve that formed a reliable landmark for the tympanic bulla, which in turn houses the round window and stapedial artery. The point of identification of facial nerve was postero-inferior to the external auditory meatus. The procedure was then repeated in living animals. RESULTS Seventeen cadaveric rats were dissected. Initially, the investigators attempted to identify the facial nerve at its crossing over the external auditory meatus. However, that method was found to be unsatisfactory. The facial nerve was then attempted to be identified in its course postero-inferior to the external auditory meatus. The technique improved drastically, and the facial nerve was identified promptly and reliably. The procedure was then repeated in seven living rats under general anaesthesia. The major issues encountered were bleeding from the stapedial artery, hematoma of the pinna in one rat. CONCLUSION This study suggests that the post-auricular approach is a feasible and less time consuming route for round window drug delivery experiments in Wistar albino rats. Recognition of anatomical landmarks, particularly the facial nerve is the key to surgery.
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Affiliation(s)
- Barilin Dkhar
- Department of ENT, North Eastern Indira Gandhi Regional Institute of Health & Medical Sciences (NEIGRIHMS), Shillong, 793018, Meghalaya, India
| | - Abhijeet Bhatia
- Department of ENT, North Eastern Indira Gandhi Regional Institute of Health & Medical Sciences (NEIGRIHMS), Shillong, 793018, Meghalaya, India.
| | - Pranjal Pratim Saikia
- Department of Pharmacology, North Eastern Indira Gandhi Regional Institute of Health & Medical Sciences (NEIGRIHMS), Shillong, 793018, Meghalaya, India
| | - Haphidasara Pyngrope
- Department of ENT, North Eastern Indira Gandhi Regional Institute of Health & Medical Sciences (NEIGRIHMS), Shillong, 793018, Meghalaya, India
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8
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Leterme G, Guigou C, Oudot A, Collin B, Boudon J, Millot N, Geissler A, Belharet K, Bozorg Grayeli A. Superparamagnetic Nanoparticle Delivery to the Cochlea Through Round Window by External Magnetic Field: Feasibility and Toxicity. Surg Innov 2019; 26:646-655. [PMID: 31478462 DOI: 10.1177/1553350619867217] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Introduction. The objective of this study was to evaluate the feasibility and toxicity of superparamagnetic iron oxide nanoparticles (SPIONs) administered into the cochlea through the round window (RW) by an external magnetic field. Materials and Methods. In 5 Wistar rats, the left RW was punctured. SPIONs suspended in hyaluronic gel (5 mg/mL) were applied in the RW niche and covered by a muscle graft. The nanoparticles were mobilized using a rare earth magnet (0.54 T) held in 4 consecutive positions around the head. The right ear served as control. Hearing function was monitored by auditory brainstem responses (4-32 kHz tone bursts). Results. The auditory thresholds remained unchanged 1 month after the administration. The histological study of the cochleae showed that SPIONs were driven into the scala tympani in the basal turn, the second turn, and the apex. Conclusion. Superparamagnetic nanoparticles can be driven inside the cochlea toward the apex with a preserved hearing up to 1 month in rats.
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Affiliation(s)
- Gaëlle Leterme
- Otolaryngology Department, Dijon University Hospital, Dijon, France.,Laboratoire Imvia, Université Bourgogne-Franche-Comté, Dijon, France
| | - Caroline Guigou
- Otolaryngology Department, Dijon University Hospital, Dijon, France.,Laboratoire Imvia, Université Bourgogne-Franche-Comté, Dijon, France
| | | | - Bertrand Collin
- Centre Georges François Leclerc, Dijon, France.,ICMUB, UMR 6302 CNRS/Université Bourgogne Franche-Comté, Dijon, France
| | - Julien Boudon
- Laboratoire ICB, UMR 6303 CNRS/Université Bourgogne Franche-Comté, Dijon, France
| | - Nadine Millot
- Laboratoire ICB, UMR 6303 CNRS/Université Bourgogne Franche-Comté, Dijon, France
| | - Audrey Geissler
- Plateforme d'imagerie cellulaire CellImaP, Université Bourgogne-Franche-Comté, Dijon, France
| | - Karim Belharet
- Laboratoire PRISME, HEI Campus Centre, Châteauroux, France
| | - Alexis Bozorg Grayeli
- Otolaryngology Department, Dijon University Hospital, Dijon, France.,Laboratoire Imvia, Université Bourgogne-Franche-Comté, Dijon, France
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Qian XH, Wu YC, Yang TY, Cheng CH, Chu HC, Cheng WH, Yen TY, Lin TH, Lin YJ, Lee YC, Chang JH, Lin ST, Li SH, Wu TC, Huang CC, Wang SH, Lee CF, Yang CH, Hung CC, Chi TS, Liu CH, Ker MD, Wu CY. Design and In Vivo Verification of a CMOS Bone-Guided Cochlear Implant Microsystem. IEEE Trans Biomed Eng 2019; 66:3156-3167. [PMID: 30802846 DOI: 10.1109/tbme.2019.2901374] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE To develop and verify a CMOS bone-guided cochlear implant (BGCI) microsystem with electrodes placed on the bone surface of the cochlea and the outside of round window for treating high-frequency hearing loss. METHODS The BGCI microsystem consists of an external unit and an implanted unit. The external system-on-chip is designed to process acoustic signals through an acquisition circuit and an acoustic DSP processor to generate stimulation patterns and commands that are transmitted to the implanted unit through a 13.56 MHz wireless power and bidirectional data telemetry. In the wireless power telemetry, a voltage doubler/tripler (2X/3X) active rectifier is used to enhance the power conversion efficiency and generate 2 and 3 V output voltages. In the wireless data telemetry, phase-locked loop based binary phase-shift keying and load-shift keying modulators/demodulators are adopted for the downlink and uplink data through high-Q coils, respectively. The implanted chip with four-channel high-voltage-tolerant stimulator generates biphasic stimulation currents up to 800 μA. RESULTS Electrical tests on the fabricated BGCI microsystem have been performed to verify the chip functions. The in vivo animal tests in guinea pigs have shown the evoked third wave of electrically evoked auditory brainstem response waveforms. It is verified that auditory nerves can be successfully stimulated and acoustic hearing can be partially preserved. CONCLUSION AND SIGNIFICANCE Different from traditional cochlear implants, the proposed BGCI microsystem is less invasive, preserves partially acoustic hearing, and provides an effective alternative for treating high-frequency hearing loss.
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10
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Mamach M, Kessler M, Bankstahl JP, Wilke F, Geworski L, Bengel FM, Kurt S, Berding G. Visualization of the auditory pathway in rats with 18F-FDG PET activation studies based on different auditory stimuli and reference conditions including cochlea ablation. PLoS One 2018; 13:e0205044. [PMID: 30278068 PMCID: PMC6168174 DOI: 10.1371/journal.pone.0205044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 09/18/2018] [Indexed: 11/18/2022] Open
Abstract
Activation studies with positron emission tomography (PET) in auditory implant users explained some of the mechanisms underlying the variability of achieved speech comprehension. Since future developments of auditory implants will include studies in rodents, we aimed to inversely translate functional PET imaging to rats. In normal hearing rats, activity in auditory and non-auditory regions was studied using 18F-fluorodeoxyglucose (18F-FDG) PET with 3 different acoustic conditions: sound attenuated laboratory background, continuous white noise and rippled noise. Additionally, bilateral cochlea ablated animals were scanned. 3D image data were transferred into a stereotaxic standard space and evaluated using volume of interest (VOI) analyses and statistical parametric mapping (SPM). In normal hearing rats alongside the auditory pathway consistent activations of the nucleus cochlearis (NC), olivary complex (OC) and inferior colliculus (IC) were seen comparing stimuli with background. In this respect, no increased activation could be detected in the auditory cortex (AC), which even showed deactivation with white noise stimulation. Nevertheless, higher activity in the AC in normal hearing rats was observed for all 3 auditory conditions against the cochlea ablated status. Vice versa, in ablated status activity in the olfactory nucleus (ON) was higher compared to all auditory conditions in normal hearing rats. Our results indicate that activations can be demonstrated in normal hearing animals based on 18F-FDG PET in nuclei along the central auditory pathway with different types of noise stimuli. However, in the AC missing activation with respect to the background advises the need for more rigorous background noise attenuation for non-invasive reference conditions. Finally, our data suggest cross-modal activation of the olfactory system following cochlea ablation–underlining, that 18F-FDG PET appears to be well suited to study plasticity in rat models for cochlear implantation.
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Affiliation(s)
- Martin Mamach
- Department of Medical Physics and Radiation Protection, Hannover Medical School, Hannover, Germany
- Cluster of Excellence Hearing4all, Hannover Medical School, Hannover, Germany
- * E-mail:
| | - Mariella Kessler
- Cluster of Excellence Hearing4all, Hannover Medical School, Hannover, Germany
- Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany
| | - Jens P. Bankstahl
- Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany
| | - Florian Wilke
- Department of Medical Physics and Radiation Protection, Hannover Medical School, Hannover, Germany
| | - Lilli Geworski
- Department of Medical Physics and Radiation Protection, Hannover Medical School, Hannover, Germany
| | - Frank M. Bengel
- Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany
| | - Simone Kurt
- Cluster of Excellence Hearing4all, Hannover Medical School, Hannover, Germany
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine CIPMM, Saarland University, Homburg, Germany
| | - Georg Berding
- Cluster of Excellence Hearing4all, Hannover Medical School, Hannover, Germany
- Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany
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11
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Shepherd RK, Villalobos J, Burns O, Nayagam DAX. The development of neural stimulators: a review of preclinical safety and efficacy studies. J Neural Eng 2018; 15:041004. [PMID: 29756600 PMCID: PMC6049833 DOI: 10.1088/1741-2552/aac43c] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Given the rapid expansion of the field of neural stimulation and the rigorous regulatory approval requirements required before these devices can be applied clinically, it is important that there is clarity around conducting preclinical safety and efficacy studies required for the development of this technology. APPROACH The present review examines basic design principles associated with the development of a safe neural stimulator and describes the suite of preclinical safety studies that need to be considered when taking a device to clinical trial. MAIN RESULTS Neural stimulators are active implantable devices that provide therapeutic intervention, sensory feedback or improved motor control via electrical stimulation of neural or neuro-muscular tissue in response to trauma or disease. Because of their complexity, regulatory bodies classify these devices in the highest risk category (Class III), and they are therefore required to go through a rigorous regulatory approval process before progressing to market. The successful development of these devices is achieved through close collaboration across disciplines including engineers, scientists and a surgical/clinical team, and the adherence to clear design principles. Preclinical studies form one of several key components in the development pathway from concept to product release of neural stimulators. Importantly, these studies provide iterative feedback in order to optimise the final design of the device. Key components of any preclinical evaluation include: in vitro studies that are focussed on device reliability and include accelerated testing under highly controlled environments; in vivo studies using animal models of the disease or injury in order to assess efficacy and, given an appropriate animal model, the safety of the technology under both passive and electrically active conditions; and human cadaver and ex vivo studies designed to ensure the device's form factor conforms to human anatomy, to optimise the surgical approach and to develop any specialist surgical tooling required. SIGNIFICANCE The pipeline from concept to commercialisation of these devices is long and expensive; careful attention to both device design and its preclinical evaluation will have significant impact on the duration and cost associated with taking a device through to commercialisation. Carefully controlled in vitro and in vivo studies together with ex vivo and human cadaver trials are key components of a thorough preclinical evaluation of any new neural stimulator.
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Affiliation(s)
- Robert K Shepherd
- Bionics Institute, East Melbourne, Australia. Medical Bionics Department, University of Melbourne, Melbourne, Australia
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12
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Zhong LL, Zhang Y, Liang XJ, Hou K, Han JW, Wang FY, Hao QQ, Jiang QQ, Yu N, Guo WW, Yang SM. Inner ear structure of miniature pigs measured by multi-planar reconstruction techniques. Am J Transl Res 2018; 10:709-717. [PMID: 29636861 PMCID: PMC5883112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 11/21/2017] [Indexed: 06/08/2023]
Abstract
To study the structures of the scala vestibuli and tympani of miniature pigs in order to evaluate the feasibility of using miniature pigs as the animal model for cochlear implant. The temporal bones of three miniature pigs with normal hearing were scanned by micro-CT. With the aid of the Mimics software, we reconstructed the 3D structure of inner ear basing on the serial images of the miniature pig, and obtained dimensions of the scala vestibuli and tympani with multi-planar reconstruction (MPR) technique. The constructed slicing images displayed the fine structures of the cochlea. The results of our study showed that the cross-sectional areas of the scala tympani were greatest at 2.67 ± 0.90 mm2 when the circumferential length from the starting point of basal turn of the cochlea reached to 1.16 mm. The scala vestibuli has a largest width and height at the starting point of basal turn. The width and the height were 2.65 ± 0.45 mm and 2.43 ± 0.2 mm respectively. The largest width and height of the scala tympani were 2.17 ± 0.30 mm and 1.83 ± 0.42 mm. The result of our study suggests that the cochlea of miniature pigs is highly consistent with human's. Miniature pigs may be used as a new model for cochlear implant. MPR technique may be used as a new approach to obtain further information of patient's cochlea in surgeons which is helpful to select suitable cochlear implant devices and surgery approach.
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Affiliation(s)
- Ling-Ling Zhong
- Department of Otolayngology, Head & Neck Surgery, Institute of Otolaryngology of PLA, Chinese PLA General HospitalBeijing 100853, P. R. China
- Department of Otolayngology, Head & Neck Surgery, The Tianjin Children’s HospitalTianjin 300074, P. R. China
| | - Yan Zhang
- Department of Otorhinolaryngology Head and Neck Surgery, The First Hospital of Jilin UniversityChangchun 130021, Jilin, P. R. China
| | - Xiao-Jie Liang
- Department of Otolaryngeal-Head Neck Surgery, The Army General Hospita of PLABeijing 100700, P. R. China
| | - Kun Hou
- Department of Otolayngology, Head & Neck Surgery, Institute of Otolaryngology of PLA, Chinese PLA General HospitalBeijing 100853, P. R. China
| | - Jia-Wei Han
- Department of Otolayngology, Head & Neck Surgery, Institute of Otolaryngology of PLA, Chinese PLA General HospitalBeijing 100853, P. R. China
| | - Fang-Yuan Wang
- Department of Otolayngology, Head & Neck Surgery, Institute of Otolaryngology of PLA, Chinese PLA General HospitalBeijing 100853, P. R. China
| | - Qing-Qing Hao
- Department of Otolayngology, Head & Neck Surgery, Institute of Otolaryngology of PLA, Chinese PLA General HospitalBeijing 100853, P. R. China
| | - Qing-Qing Jiang
- Department of Otolayngology, Head & Neck Surgery, Institute of Otolaryngology of PLA, Chinese PLA General HospitalBeijing 100853, P. R. China
| | - Ning Yu
- Department of Otolayngology, Head & Neck Surgery, Institute of Otolaryngology of PLA, Chinese PLA General HospitalBeijing 100853, P. R. China
| | - Wei-Wei Guo
- Department of Otolayngology, Head & Neck Surgery, Institute of Otolaryngology of PLA, Chinese PLA General HospitalBeijing 100853, P. R. China
| | - Shi-Ming Yang
- Department of Otolayngology, Head & Neck Surgery, Institute of Otolaryngology of PLA, Chinese PLA General HospitalBeijing 100853, P. R. China
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Matsuoka AJ, Sayed ZA, Stephanopoulos N, Berns EJ, Wadhwani AR, Morrissey ZD, Chadly DM, Kobayashi S, Edelbrock AN, Mashimo T, Miller CA, McGuire TL, Stupp SI, Kessler JA. Creating a stem cell niche in the inner ear using self-assembling peptide amphiphiles. PLoS One 2017; 12:e0190150. [PMID: 29284013 PMCID: PMC5746215 DOI: 10.1371/journal.pone.0190150] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 12/09/2017] [Indexed: 11/23/2022] Open
Abstract
The use of human embryonic stem cells (hESCs) for regeneration of the spiral ganglion will require techniques for promoting otic neuronal progenitor (ONP) differentiation, anchoring of cells to anatomically appropriate and specific niches, and long-term cell survival after transplantation. In this study, we used self-assembling peptide amphiphile (PA) molecules that display an IKVAV epitope (IKVAV-PA) to create a niche for hESC-derived ONPs that supported neuronal differentiation and survival both in vitro and in vivo after transplantation into rodent inner ears. A feature of the IKVAV-PA gel is its ability to form organized nanofibers that promote directed neurite growth. Culture of hESC-derived ONPs in IKVAV-PA gels did not alter cell proliferation or viability. However, the presence of IKVAV-PA gels increased the number of cells expressing the neuronal marker beta-III tubulin and improved neurite extension. The self-assembly properties of the IKVAV-PA gel allowed it to be injected as a liquid into the inner ear to create a biophysical niche for transplanted cells after gelation in vivo. Injection of ONPs combined with IKVAV-PA into the modiolus of X-SCID rats increased survival and localization of the cells around the injection site compared to controls. Human cadaveric temporal bone studies demonstrated the technical feasibility of a transmastoid surgical approach for clinical intracochlear injection of the IKVAV-PA/ONP combination. Combining stem cell transplantation with injection of self-assembling PA gels to create a supportive niche may improve clinical approaches to spiral ganglion regeneration.
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Affiliation(s)
- Akihiro J. Matsuoka
- Department of Otolaryngology and Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
- Department of Communication Sciences and Disorders, Northwestern University, Evanston, Illinois, United States of America
- Hugh Knowles Center for Hearing Research, Northwestern University, Evanston, Illinois, United States of America
- * E-mail:
| | - Zafar A. Sayed
- Department of Otolaryngology and Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Nicholas Stephanopoulos
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, Illinois, United States of America
| | - Eric J. Berns
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
| | - Anil R. Wadhwani
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Zachery D. Morrissey
- Department of Otolaryngology and Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Duncan M. Chadly
- Department of Otolaryngology and Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Shun Kobayashi
- Department of Otolaryngology and Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Alexandra N. Edelbrock
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
| | - Tomoji Mashimo
- The Institute of Experimental Animal Sciences, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Charles A. Miller
- Department of Otolaryngology and Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Tammy L. McGuire
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Samuel I. Stupp
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, Illinois, United States of America
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
- Department of Chemistry, Northwestern University, Evanston, Illinois, United States of America
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois, United States of America
| | - John A. Kessler
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
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Mülazımoğlu S, Ocak E, Kaygusuz G, Gökcan MK. Retroauricular Approach for Targeted Cochlear Therapy Experiments in Wistar Albino Rats. Balkan Med J 2017; 34:200-205. [PMID: 28443600 PMCID: PMC5450858 DOI: 10.4274/balkanmedj.2016.0226] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Background: As the idea of stem cell technology in the treatment of sensorial hearing loss has emerged over the past decades, the need for in vivo models for related experiments has become explicit. One of the most common experimental models for inner ear stem cell delivery experiments is the Wistar albino rat. Aims: To investigate the surgical anatomy of the temporal bone of the Wistar albino rat with respect to the dissection steps, operative techniques and potential pitfalls of surgery. Study Design: Animal experimentation. Methods: Adult Wistar albino rats were operated on via the retroauricular approach under an operation microscope. The anatomy of the temporal bone, the surgical route to the temporal bulla and the inner ear were investigated. Technical details of surgical steps, complications and potential pitfalls during the surgery were noted. Results: The study group consisted of 40 adult Wistar albino rats. The mean times to reach the bulla and to achieve cochleostomy were 4.3 (2-13 min) and 7.5 min (3.5-22 min), respectively. The mean width of the facial nerve was 0.84 mm (0.42-1.25 mm). The stapedial artery lay nearly perpendicular to the course of the facial nerve (88-93 °C). There were three major complications: two large cochleostomies and one massive bleed from the stapedial artery. Conclusion: The facial nerve was the key anatomical landmark in locating the bulla. By retrograde tracing of the facial nerve, it was possible to find the bulla ventral (inferior) to the main trunk. The facial nerve trunk was the upper limit when drilling the bulla. By dissecting the main trunk of the facial nerve and retracting cranially, a large drilling space could be achieved. Our results suggest that the retroauricular approach is an effective, feasible route for inner ear drug delivery experiments in Wistar albino rats.
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Affiliation(s)
- Selçuk Mülazımoğlu
- Department of Otorhinolaryngology, Ankara University School of Medicine, Ankara, Turkey
| | - Emre Ocak
- Department of Otorhinolaryngology, Keçiören Training and Research Hospital, Ankara, Turkey
| | - Gülşah Kaygusuz
- Department of Pathology, Ankara University School of Medicine, Ankara, Turkey
| | - Mustafa Kürşat Gökcan
- Department of Otorhinolaryngology, Ankara University School of Medicine, Ankara, Turkey
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15
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Wiegner A, Wright CG, Vollmer M. Multichannel cochlear implant for selective neuronal activation and chronic use in the free-moving Mongolian gerbil. J Neurosci Methods 2016; 273:40-54. [PMID: 27519925 DOI: 10.1016/j.jneumeth.2016.08.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 08/05/2016] [Accepted: 08/08/2016] [Indexed: 12/18/2022]
Abstract
BACKGROUND Animal models for chronic multichannel cochlear implant stimulation and selective neuronal activation contribute to a better understanding of auditory signal processing and central neural plasticity. NEW METHOD This paper describes the design and surgical implantation of a multichannel cochlear implant (CI) system for chronic use in the free-moving gerbil. For chronic stimulation, adult-deafened gerbils were connected to a multichannel commutator that allowed low resistance cable rotation and stable electric connectivity to the current source. RESULTS Despite the small scale of the gerbil cochlea and auditory brain regions, final electrophysiological mapping experiments revealed selective and tonotopically organized neuronal activation in the auditory cortex. Contact impedances and electrically evoked auditory brainstem responses were stable over several weeks demonstrating the long-term integrity of the implant and the efficacy of the stimulation. COMPARISON WITH EXISTING METHODS Most animal models on multichannel signal processing and stimulation-induced plasticity are limited to larger animals such as ferrets, cats and primates. Multichannel CI stimulation in the free-moving rodent and evidence for selective neuronal activation in gerbil auditory cortex have not been previously reported. CONCLUSIONS Overall, our results show that the gerbil is a robust rodent model for selective and tonotopically organized multichannel CI stimulation. We anticipate that this model provides a useful tool to develop and test both passive stimulation and behavioral training strategies for plastic reorganization and restoration of degraded unilateral and bilateral central auditory signal processing in the hearing impaired and deaf central auditory system.
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Affiliation(s)
- Armin Wiegner
- Comprehensive Hearing Center, University Hospital Wuerzburg, Josef-Schneider-Str. 11, 97080 Wuerzburg, Germany.
| | - Charles G Wright
- Department of Otolaryngology-Head and Neck Surgery, Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, United States.
| | - Maike Vollmer
- Comprehensive Hearing Center, University Hospital Wuerzburg, Josef-Schneider-Str. 11, 97080 Wuerzburg, Germany.
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16
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King J, Shehu I, Roland JT, Svirsky MA, Froemke RC. A physiological and behavioral system for hearing restoration with cochlear implants. J Neurophysiol 2016; 116:844-58. [PMID: 27281743 DOI: 10.1152/jn.00048.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 05/31/2016] [Indexed: 12/31/2022] Open
Abstract
Cochlear implants are neuroprosthetic devices that provide hearing to deaf patients, although outcomes are highly variable even with prolonged training and use. The central auditory system must process cochlear implant signals, but it is unclear how neural circuits adapt-or fail to adapt-to such inputs. The knowledge of these mechanisms is required for development of next-generation neuroprosthetics that interface with existing neural circuits and enable synaptic plasticity to improve perceptual outcomes. Here, we describe a new system for cochlear implant insertion, stimulation, and behavioral training in rats. Animals were first ensured to have significant hearing loss via physiological and behavioral criteria. We developed a surgical approach for multichannel (2- or 8-channel) array insertion, comparable with implantation procedures and depth in humans. Peripheral and cortical responses to stimulation were used to program the implant objectively. Animals fitted with implants learned to use them for an auditory-dependent task that assesses frequency detection and recognition in a background of environmentally and self-generated noise and ceased responding appropriately to sounds when the implant was temporarily inactivated. This physiologically calibrated and behaviorally validated system provides a powerful opportunity to study the neural basis of neuroprosthetic device use and plasticity.
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Affiliation(s)
- Julia King
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, New York; Neuroscience Institute, New York University School of Medicine, New York, New York; Department of Otolaryngology, New York University School of Medicine, New York, New York; Department of Neuroscience and Physiology, New York University School of Medicine, New York, New York
| | - Ina Shehu
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, New York; Department of Otolaryngology, New York University School of Medicine, New York, New York; Department of Biology, Hunter College, New York, New York; and
| | - J Thomas Roland
- Department of Otolaryngology, New York University School of Medicine, New York, New York
| | - Mario A Svirsky
- Neuroscience Institute, New York University School of Medicine, New York, New York; Department of Otolaryngology, New York University School of Medicine, New York, New York; Department of Neuroscience and Physiology, New York University School of Medicine, New York, New York; Center for Neural Science, New York University, New York, New York. *, co-senior authors
| | - Robert C Froemke
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, New York; Neuroscience Institute, New York University School of Medicine, New York, New York; Department of Otolaryngology, New York University School of Medicine, New York, New York; Department of Neuroscience and Physiology, New York University School of Medicine, New York, New York; Center for Neural Science, New York University, New York, New York. *, co-senior authors.
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17
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Risoud M, Bonne NX, Fourdrinier M, Hubert T, Vincent C. Technical note for post-auricular route surgery in Mongolian gerbil. Hear Res 2016; 337:65-9. [PMID: 27244698 DOI: 10.1016/j.heares.2016.05.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Revised: 05/19/2016] [Accepted: 05/24/2016] [Indexed: 11/19/2022]
Abstract
The Mongolian gerbil (Meriones unguiculatus) is commonly used in hearing research because the hearing frequency spectrum of the gerbil is rather similar to that of the human being. However, a precise description of the surgical post-auricular route has not been reported. The aim of this technical note is to provide details on the procedure and the surgical anatomy of the post-auricular route in the Mongolian gerbil. Surgery was performed under general anesthesia on eight (2 males and 6 females) adult Mongolian gerbils. All steps of the post-auricular route were detailed. This surgery provided an access to the following structures: the semi-circular posterior and lateral canals, the external auditory meatus, the tympanic membrane, the round window, the stapes, the stapedial artery and the reliefs of the cochlea. No anatomic variation was noticed among the 8 animals. This post-auricular route in the Mongolian gerbil defines a brief and simple surgery, overall standardized as a consequence of the absence of common anatomic variation, with painless and uncomplicated post-operative stage.
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Affiliation(s)
- Michaël Risoud
- CHU Lille, Department of Otology and Neurotology, F-59000 Lille, France; Univ. Lille 2, CHU Lille, INSERM U1008, Controlled Drug Delivery Systems and Biomaterials, F-59000 Lille, France.
| | - Nicolas-Xavier Bonne
- CHU Lille, Department of Otology and Neurotology, F-59000 Lille, France; Univ. Lille 2, CHU Lille, INSERM U1008, Controlled Drug Delivery Systems and Biomaterials, F-59000 Lille, France
| | - Martin Fourdrinier
- Univ. Lille 2, CHU Lille, Experimental Resources Platform, Animal Housing Facility, F-59000 Lille, France
| | - Thomas Hubert
- Univ. Lille 2, CHU Lille, Experimental Resources Platform, Animal Housing Facility, F-59000 Lille, France
| | - Christophe Vincent
- CHU Lille, Department of Otology and Neurotology, F-59000 Lille, France; Univ. Lille 2, CHU Lille, INSERM U1008, Controlled Drug Delivery Systems and Biomaterials, F-59000 Lille, France
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18
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Effect of embedded optical fibres on the mechanical properties of cochlear electrode arrays. Med Eng Phys 2016; 38:155-62. [DOI: 10.1016/j.medengphy.2015.11.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 11/11/2015] [Accepted: 11/24/2015] [Indexed: 11/22/2022]
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Cochlear implantation in the mouse via the round window: effects of array insertion. Hear Res 2014; 312:81-90. [PMID: 24657211 DOI: 10.1016/j.heares.2014.03.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Revised: 02/05/2014] [Accepted: 03/05/2014] [Indexed: 02/07/2023]
Abstract
Animal models are the only means of assessing the effects of cochlear implantation (CI) at a cellular and molecular level. The range of naturally occurring and genetically-modified mouse strains which mimic human deafness provide excellent opportunities for auditory research. To date, there are very few studies of CI in mice. The main aims of this study were to develop a reproducible and viable technique to enable long term CI in the mouse and to assess the response of the mouse cochlea to implantation as a means of evaluating the success of the procedure. Electrode array implantation via the round window was performed in C57Bl/6 mice aged 3 and 6 months. The contralateral cochlea acted as a control. Auditory brainstem responses (ABR) were recorded prior to and following CI. Analysis showed greater threshold shifts in the implanted ear compared to the control ear post-implantation, but substantial preservation of hearing. There were no cases in which implantation caused a profound hearing loss across all frequencies. Cone beam computerised tomography and light microscopy confirmed correct placement of the electrode array within the scala tympani. Cochleae were prepared for histological examination. Initial analysis revealed encapsulation of the implant in tissue with morphological characteristics suggestive of fibrosis. Our results show that mouse CI via the round window offers a model for exploring tissue responses to implantation.
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20
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Irving S, Trotter MI, Fallon JB, Millard RE, Shepherd RK, Wise AK. Cochlear implantation for chronic electrical stimulation in the mouse. Hear Res 2013; 306:37-45. [PMID: 24055621 DOI: 10.1016/j.heares.2013.09.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 08/23/2013] [Accepted: 09/09/2013] [Indexed: 01/02/2023]
Abstract
The mouse is becoming an increasingly attractive model for auditory research due to the number of genetic deafness models available. These genetic models offer the researcher an array of congenital causes of hearing impairment, and are therefore of high clinical relevance. To date, the use of mice in cochlear implant research has not been possible due to the lack of an intracochlear electrode array and stimulator small enough for murine use, coupled with the difficulty of the surgery in this species. Here, we present a fully-implantable intracochlear electrode stimulator assembly designed for chronic implantation in the mouse. We describe the surgical approach for implantation, as well as presenting the first functional data obtained from intracochlear electrical stimulation in the mouse.
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Affiliation(s)
- S Irving
- Bionics Institute, Melbourne, Australia; Department of Psychology, University of Melbourne, Australia
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Bergin M, Vlajkovic S, Bird P, Thorne P. Systematic review of animal models of middle ear surgery. World J Otorhinolaryngol 2013; 3:71-88. [DOI: 10.5319/wjo.v3.i3.71] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 08/09/2013] [Accepted: 08/20/2013] [Indexed: 02/06/2023] Open
Abstract
Animal models of middle ear surgery help us to explore disease processes and intervention outcomes in a manner not possible in patients. This review begins with an overview of animal models of middle ear surgery which outlines the advantages and limitations of such models. Procedures of interest include myringoplasty/tympanoplasty, mastoidectomy, ossiculoplasty, stapedectomy, and active middle ear implants. The most important issue is how well the model reflects the human response to surgery. Primates are most similar to humans with respect to anatomy; however, such studies are uncommon now due to expense and ethical issues. Conversely, small animals are easily obtained and housed, but experimental findings may not accurately represent what happens in humans. We then present a systematic review of animal models of middle ear surgery. Particular attention is paid to any distinctive anatomical features of the middle ear, the method of accessing the middle ear and the chosen outcomes. These outcomes are classified as either physiological in live animals, (e.g., behavioural or electrophysiological responses), or anatomical in cadaveric animals, (e.g., light or electron microscopy). Evoked physiological measures are limited by the disruption of the evoking air-conducted sound across the manipulated middle ear. The eleven identified species suitable as animal models are mouse, rat, gerbil, chinchilla, guinea pig, rabbit, cat, dog, sheep, pig and primate. Advantages and disadvantages of each species as a middle ear surgical model are outlined, and a suggested framework to aid in choosing a particular model is presented.
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Soken H, Robinson BK, Goodman SS, Abbas PJ, Hansen MR, Kopelovich JC. Mouse cochleostomy: a minimally invasive dorsal approach for modeling cochlear implantation. Laryngoscope 2013; 123:E109-15. [PMID: 23674233 DOI: 10.1002/lary.24174] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 02/25/2013] [Accepted: 04/02/2013] [Indexed: 11/05/2022]
Abstract
OBJECTIVES/HYPOTHESIS The murine model has been used extensively to model and study human deafness. Technical difficulty in the surgical approach due to the small size of the tympanic bulla and a robust stapedial artery has limited its application for studies of cochlear implantation and electrical stimulation. We describe a minimally traumatic, stapedial artery-sparing approach to the round window that may be used to access the mouse cochlea for acute or chronic studies of implantation and stimulation. STUDY DESIGN Animal model. METHODS Fifteen C57BL6J mice were used to validate this approach. Auditory brainstem response threshold and distortion product otoacoustic emissions were obtained preoperatively and 2 weeks postoperatively to determine hearing preservation results. RESULTS The approach provided excellent exposure for round-window implantation. Substantial hearing was preserved in all animals with a mean postimplantation auditory brainstem response threshold increase of 27.8 dB. Otoacoustic emissions were lost in subjects with the largest threshold shifts. CONCLUSIONS Residual hearing after cochlear implantation is a determinant of success both with standard cochlear implant electrodes and with electrodes designed to optimize hearing preservation. Here, we have preserved usable hearing after implantation of C57BL6J mice, an endogenous model of human presbycusia. The murine model may become a powerful tool to assay the effects of cochlear intervention in different genetic backgrounds.
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Affiliation(s)
- Hakan Soken
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, Iowa, U.S.A
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Sheep as a large animal model for middle and inner ear implantable hearing devices: a feasibility study in cadavers. Otol Neurotol 2012; 33:481-9. [PMID: 22410732 DOI: 10.1097/mao.0b013e318248ee3a] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
OBJECTIVE Currently, no large animal model exists for surgical-experimental exploratory analysis of implantable hearing devices. In a histomorphometric study, we sought to investigate whether sheep or pig cochleae are suitable for this purpose and whether device implantation is feasible. METHODS Skulls of pig and sheep cadavers were examined using high-resolution 128-slice computed tomography (CT) to study anatomic relationships. A cochlear implant and an active middle ear implant could be successfully implanted into the sheep's inner and middle ear, respectively. Correct device placement was verified by CT and histology. The cochlear anatomy of the sheep was further studied by micro-CT and histology. RESULTS Our investigations indicate that the sheep is a suitable animal model for implantation of implantable hearing devices. The implantation of the devices was successfully performed by access through a mastoidectomy. The histologic, morphologic, and micro-CT study of the sheep cochlea showed that it is highly similar to the human cochlea. The temporal bone of the pig was not suitable for these microsurgical procedures because the middle and inner ear were not accessible owing to distinct soft and fatty tissue coverage of the mastoid. CONCLUSION The sheep is an appropriate large animal model for experimental studies with implantable hearing devices, whereas the pig is not.
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Johnson LA, Della Santina CC, Wang X. Temporal bone characterization and cochlear implant feasibility in the common marmoset (Callithrix jacchus). Hear Res 2012; 290:37-44. [PMID: 22583919 DOI: 10.1016/j.heares.2012.05.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Revised: 04/28/2012] [Accepted: 05/03/2012] [Indexed: 10/28/2022]
Abstract
The marmoset (Callithrix jacchus) is a valuable non-human primate model for studying behavioral and neural mechanisms related to vocal communication. It is also well suited for investigating neural mechanisms related to cochlear implants. The purpose of this study was to characterize marmoset temporal bone anatomy and investigate the feasibility of implanting a multi-channel intracochlear electrode into the marmoset scala tympani. Micro computed tomography (microCT) was used to create high-resolution images of marmoset temporal bones. Cochlear fluid spaces, middle ear ossicles, semicircular canals and the surrounding temporal bone were reconstructed in three-dimensional space. Our results show that the marmoset cochlea is ∼16.5 mm in length and has ∼2.8 turns. The cross-sectional area of the scala tympani is greatest (∼0.8 mm(2)) at ∼1.75 mm from the base of the scala, reduces to ∼0.4 mm(2) at 5 mm from the base, and decreases at a constant rate for the remaining length. Interestingly, this length-area profile, when scaled 2.5 times, is similar to the scala tympani of the human cochlea. Given these dimensions, a compatible multi-channel implant electrode was identified. In a cadaveric specimen, this electrode was inserted ¾ turn into the scala tympani through a cochleostomy at ∼1 mm apical to the round window. The depth of the most apical electrode band was ∼8 mm. Our study provides detailed structural anatomy data for the middle and inner ear of the marmoset, and suggests the potential of the marmoset as a new non-human primate model for cochlear implant research.
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Affiliation(s)
- Luke A Johnson
- Biomedical Engineering Dept., Johns Hopkins University, 412 Traylor Research Building, 720 Rutland Avenue, Baltimore, MD 21205, USA.
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Abstract
The ability to electrically stimulate neural and other excitable tissues in behaving experimental animals is invaluable for both the development of neural prostheses and basic neurological research. We developed a fully implantable neural stimulator that is able to deliver two channels of intra-cochlear electrical stimulation in the rat. It is powered via a novel omni-directional inductive link and includes an on-board microcontroller with integrated radio link, programmable current sources and switching circuitry to generate charge-balanced biphasic stimulation. We tested the implant in vivo and were able to elicit both neural and behavioural responses. The implants continued to function for up to five months in vivo. While targeted to cochlear stimulation, with appropriate electrode arrays the stimulator is well suited to stimulating other neurons within the peripheral or central nervous systems. Moreover, it includes significant on-board data acquisition and processing capabilities, which could potentially make it a useful platform for telemetry applications, where there is a need to chronically monitor physiological variables in unrestrained animals.
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Affiliation(s)
- DWJ Perry
- Bionics Institute, Victoria, Australia
- Department of Otolaryngology, The University of Melbourne, Victoria, Australia
| | - DB Grayden
- Bionics Institute, Victoria, Australia
- NeuroEngineering Laboratory, Department of Electrical and Electronic Engineering, The University of Melbourne, Victoria, Australia
| | - RK Shepherd
- Bionics Institute, Victoria, Australia
- Department of Otolaryngology, The University of Melbourne, Victoria, Australia
| | - JB Fallon
- Bionics Institute, Victoria, Australia
- Department of Otolaryngology, The University of Melbourne, Victoria, Australia
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Hartley DEH, Vongpaisal T, Xu J, Shepherd RK, King AJ, Isaiah A. Bilateral cochlear implantation in the ferret: a novel animal model for behavioral studies. J Neurosci Methods 2010; 190:214-28. [PMID: 20576507 PMCID: PMC2938482 DOI: 10.1016/j.jneumeth.2010.05.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Revised: 05/12/2010] [Accepted: 05/19/2010] [Indexed: 11/24/2022]
Abstract
Bilateral cochlear implantation has recently been introduced with the aim of improving both speech perception in background noise and sound localization. Although evidence suggests that binaural perception is possible with two cochlear implants, results in humans are variable. To explore potential contributing factors to these variable outcomes, we have developed a behavioral animal model of bilateral cochlear implantation in a novel species, the ferret. Although ferrets are ideally suited to psychophysical and physiological assessments of binaural hearing, cochlear implantation has not been previously described in this species. This paper describes the techniques of deafening with aminoglycoside administration, surgical implantation of an intracochlear array and chronic intracochlear electrical stimulation with monitoring for electrode integrity and efficacy of stimulation. Experiments have been presented elsewhere to show that the model can be used to study behavioral and electrophysiological measures of binaural hearing in chronically implanted animals. This paper demonstrates that cochlear implantation and chronic intracochlear electrical stimulation are both safe and effective in ferrets, opening up the possibility of using this model to study potential protective effects of bilateral cochlear implantation on the developing central auditory pathway. Since ferrets can be used to assess psychophysical and physiological aspects of hearing along with the structure of the auditory pathway in the same animals, we anticipate that this model will help develop novel neuroprosthetic therapies for use in humans.
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Tan J, Widjaja S, Xu J, Shepherd RK. Cochlear implants stimulate activity-dependent CREB pathway in the deaf auditory cortex: implications for molecular plasticity induced by neural prosthetic devices. Cereb Cortex 2008; 18:1799-813. [PMID: 18063565 PMCID: PMC2790391 DOI: 10.1093/cercor/bhm206] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Neural activity modulates the maturation of synapses and their organization into functional circuits by regulating activity-dependent signaling pathways. Phosphorylation of cyclic AMP/Ca(2+)-responsive element-binding protein (CREB) is widely accepted as a stimulus-inducible event driven by calcium influx into depolarized neurons. In turn, phosphorylated CREB (pCREB) activates the transcription of brain-derived neurotrophic factor (BDNF), which is needed for synaptic transmission and long-term potentiation. We examined how these molecular events are influenced by sensorineural hearing loss and long-term reactivation via cochlear implants. Sensorineural hearing loss reduced the expression of pCREB and BDNF. In contrast, deafened animals subject to long-term, unilateral intracochlear electrical stimulation exhibited an increased expression of pCREB and BDNF in the contralateral auditory cortical neurons, relative to ipsilateral ones. These changes induced by cochlear implants are further accompanied by the activation of the mitogen-activated protein kinase (MAPK) signaling pathway, which has been implicated in long-lasting forms of synaptic plasticity. Because CREB and BDNF are critical modulators of synaptic plasticity, our data describe for the first time possible molecular candidate genes, which are altered in the auditory cortex, following cochlear implantation. These findings provide insights into adaptive, molecular mechanisms recruited by the brain upon functional electrical stimulation by neural prosthetic devices.
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Affiliation(s)
- Justin Tan
- The Bionic Ear Institute, East Melbourne, Victoria 3002, Australia.
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Wei BPC, Shepherd RK, Robins-Browne RM, Clark GM, O'Leary SJ. Pneumococcal meningitis threshold model: A potential tool to assess infectious risk of new or existing inner ear surgical interventions. Otol Neurotol 2008; 27:1152-61. [PMID: 16980916 PMCID: PMC1847393 DOI: 10.1097/01.mao.0000227898.80656.54] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
HYPOTHESIS A minimal threshold of Streptococcus pneumoniae is required to induce meningitis in healthy animals for intraperitoneal (hematogenous), middle ear, and inner ear inoculations, and this threshold may be altered via recent inner ear surgery. BACKGROUND There has been an increase in the number of reported cases of cochlear implant-related pneumococcal meningitis since 2002. The pathogenesis of pneumococcal meningitis is complex and not completely understood. The bacteria can reach the central nervous system (CNS) from the upper respiratory tract mucosa via either hematogenous route or via the inner ear. The establishment of a threshold model for all potential routes of infection to the CNS in animals without cochlear implantation is an important first step to help us understand the pathogenesis of the disease in animals with cochlear implantation. METHODS Fifty-four otologically normal adult Hooded Wistar rats (27 receiving cochleostomy and 27 controls) were inoculated with different amounts of bacterial counts via three different routes (intraperitoneal, middle ear, and inner ear). Rats were monitored during 5 days for signs of meningitis. Blood, cerebrospinal fluid, and middle ear swabs were taken for bacterial culture, and brains and cochleae were examined for signs of infection. RESULTS The threshold of bacterial counts required to induce meningitis is lowest in rats receiving direct inner ear inoculation compared with both intraperitoneal and middle ear inoculation. There is no change in threshold between the group of rats with cochleostomy and the control (Fisher's exact test, p < 0.05). CONCLUSION A minimal threshold of bacteria is required to induce meningitis in healthy animals and is different for three different routes of infection (intraperitoneal, middle ear, and inner ear). Cochleostomy performed 4 weeks before the inoculation did not reduce the threshold of bacteria required for meningitis in all three infectious routes. This threshold model will also serve as a valuable tool, assisting clinicians to quantitatively analyze if the presence of a cochlear implant or other CNS prostheses alter the risk of meningitis.
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Affiliation(s)
- Benjamin P C Wei
- Department of Otolaryngology, University of Melbourne, Melbourne, Victoria, Australia.
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Millard RE, Shepherd RK. A fully implantable stimulator for use in small laboratory animals. J Neurosci Methods 2007; 166:168-77. [PMID: 17897719 PMCID: PMC2001238 DOI: 10.1016/j.jneumeth.2007.07.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2007] [Revised: 06/01/2007] [Accepted: 07/06/2007] [Indexed: 10/23/2022]
Abstract
This paper describes a low cost, fully implantable, single channel stimulator that can be manufactured in a research laboratory. The stimulator generates charge-balanced biphasic current pulses which are delivered to a bipolar electrode array for chronic stimulation of neural tissue in free-running laboratory animals such as rats and mice. The system is magnetically coupled and contains no batteries or external leadwires. The subject is placed in a chamber surrounded by three orthogonal coils of wire which are driven to generate a magnetic field. Currents are induced in wire coils in the implanted stimulator then regulated to produce biphasic current pulses with fixed amplitude of up to 500 microA. Phase duration is adjustable from 25 to 250 micros per phase. Charge balance is maintained by capacitive coupling and shorting of the electrodes between pulses. Stimulus rate can be continuously varied, and the temporal precision of the stimulus means that the stimulator can be used in behavioural experiments or for generating electrically evoked potentials. We describe the application of this stimulator for chronic electrical stimulation of the auditory nerve (i.e. a cochlear implant); however it will have application in other areas of neuroscience requiring controlled safe electrical stimulation of neural tissue over extended periods. Circuit diagrams and manufacturing details are provided as supplementary data.
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Affiliation(s)
- Rodney E Millard
- Department of Otolaryngology, University of Melbourne, East Melbourne, Victoria 3002, Australia.
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Wei BPC, Shepherd RK, Robins-Browne RM, Clark GM, O'Leary SJ. Pneumococcal meningitis: development of a new animal model. Otol Neurotol 2007; 27:844-54. [PMID: 16936571 PMCID: PMC1839842 DOI: 10.1097/01.mao.0000231603.25961.f1] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
HYPOTHESIS The rat is a suitable animal to establish a model for the study of pneumococcal meningitis postcochlear implantation. BACKGROUND There has been an increase in the number of cases of cochlear implant-related meningitis. The most common organism identified was Streptococcus pneumoniae. Whether cochlear implantation increases the risk of pneumococcal meningitis in healthy subjects without other risk factors remains to be determined. Previous animal studies do not focus on the pathogenesis and risk of pneumococcal meningitis postimplantation and are based on relatively small animal numbers, making it difficult to assess the cause-and-effect relationship. There is, therefore, a need to develop a new animal model allowing direct examination of the pathogenesis of meningitis in the presence of a cochlear implant. METHODS Eighteen nonimplanted rats were infected with 1 x 10 and 1 x 10 colony-forming units (CFU) of a clinical isolate of S. pneumoniae via three different inoculation routes (middle ear, inner ear, and i.p.) to examine for evidence of meningitis during 24 hours. Six implanted rats were infected with the highest amount of bacteria possible for each route of inoculation (4 x 10 CFU i.p., 3 x 10 CFU middle ear, and 1 x 10 CFU inner ear) to examine for evidence of meningitis with the presence of an implant. The histological pattern of cochlear infections for each of the three different inoculating routes were examined. RESULTS Pneumococcal meningitis was evident in all 6 implanted animals for each of the three different routes of inoculation. Once in the inner ear, bacteria were found to enter the central nervous system via either the cochlear aqueduct or canaliculi perforantes of the osseous spiral lamina, reaching the perineural and perivascular space then the internal acoustic meatus. The rate, extent, and pattern of infection within the cochleae depended on the route of inoculation. Finally, there was no evidence of pneumococcal meningitis observed in 18 nonimplanted rats inoculated at a lower concentration of S. pneumoniae when observed for 24 hours postinoculation. CONCLUSION Meningitis in implanted rats after inoculation with a clinical isolate of S. pneumoniae is possible via all three potential routes of infection via the upper respiratory tract. The lack of meningitis observed in the 18 nonimplanted rats suggests that longer postinoculation monitoring periods are required to ensure whether or not meningitis will develop. Based on this work, we have developed a new animal model that will allow quantitative risk assessment of meningitis postcochlear implantation, and the assessment of the efficacy of potential interventional strategies in future studies.
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Affiliation(s)
- Benjamin P C Wei
- Bionic Ear Institute, Department of Otolaryngology, University of Melbourne, Royal Victorian Eye & Ear Hospital, Melbourne, Victoria, Australia.
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Wei BPC, Shepherd RK, Robins-Browne RM, Clark GM, O'Leary SJ. Threshold shift: effects of cochlear implantation on the risk of pneumococcal meningitis. Otolaryngol Head Neck Surg 2007; 136:589-96. [PMID: 17418257 PMCID: PMC1852444 DOI: 10.1016/j.otohns.2006.11.039] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Accepted: 11/20/2006] [Indexed: 10/23/2022]
Abstract
OBJECTIVES The study goals were to examine whether cochlear implantation increases the risk of meningitis in the absence of other risk factors and to understand the pathogenesis of pneumococcal meningitis post cochlear implantation. STUDY DESIGN AND SETTING Four weeks following surgery, 54 rats (18 of which received a cochleostomy alone, 18 of which received a cochleostomy and acute cochlear implantation using standard surgical techniques, and 18 of which received a cochlear implant) were infected with Streptococcus pneumoniae via three different routes of bacterial inoculation (middle ear, inner ear, and intraperitoneal) to represent all potential routes of bacterial infection from the upper respiratory tract to the meninges. RESULTS The presence of a cochlear implant reduced the threshold of bacteria required to cause pneumococcal meningitis from all routes of infection in healthy animals. CONCLUSION The presence of a cochlear implant increases the risk of pneumococcal meningitis regardless of the route of bacterial infection. SIGNIFICANCE Early detection and treatment of pneumococcal infection such as otitis media may be required, as cochlear implantation may lead to a reduction of infectious threshold for meningitis.
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Affiliation(s)
- Benjamin P C Wei
- Bionic Ear Institute, the University of Melbourne, Melbourne, Victoria, Australia.
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Wei BPC, Shepherd RK, Robins-Browne RM, Clark GM, O'Leary SJ. Effects of inner ear trauma on the risk of pneumococcal meningitis. ACTA ACUST UNITED AC 2007; 133:250-9. [PMID: 17372082 PMCID: PMC1840049 DOI: 10.1001/archotol.133.3.250] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE To examine the risk of pneumococcal meningitis in healthy rats that received a severe surgical trauma to the modiolus and osseous spiral lamina or the standard insertion technique for acute cochlear implantation. DESIGN Interventional animal studies. SUBJECTS Fifty-four otologically normal adult Hooded-Wistar rats. INTERVENTIONS Fifty-four rats (18 of which received a cochleostomy alone; 18, a cochleostomy and acute cochlear implantation using standard surgical techniques; and 18, a cochleostomy followed by severe inner ear trauma) were infected 4 weeks after surgery with Streptococcus pneumoniae via 3 different routes (hematogenous, middle ear, and inner ear) to represent all potential routes of bacterial infection from the upper respiratory tract to the meninges in cochlear implant recipients with meningitis. RESULTS Severe trauma to the osseous spiral lamina and modiolus increased the risk of pneumococcal meningitis when the bacteria were given via the middle or inner ear (Fisher exact test, P<.05). However, the risk of meningitis did not change when the bacteria were given via the hematogenous route. Acute electrode insertion did not alter the risk of subsequent pneumococcal meningitis for any route of infection. CONCLUSIONS Severe inner ear surgical trauma to the osseous spiral lamina and modiolus can increase the risk of pneumococcal meningitis. Therefore, every effort should be made to ensure that cochlear implant design and insertion technique cause minimal trauma to the bony structures of the inner ear to reduce the risk of pneumococcal meningitis.
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Affiliation(s)
- Benjamin P C Wei
- Bionic Ear Institute and Departments of Otolaryngology and Microbiology and Immunology, University of Melbourne, Melbourne, Australia.
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