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Jwair S, Ramekers D, Thomeer HGXM, Versnel H. Acute effects of cochleostomy and electrode-array insertion on compound action potentials in normal-hearing guinea pigs. Front Neurosci 2023; 17:978230. [PMID: 36845413 PMCID: PMC9945226 DOI: 10.3389/fnins.2023.978230] [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: 06/25/2022] [Accepted: 01/09/2023] [Indexed: 02/11/2023] Open
Abstract
Introduction Electrocochleography (ECochG) is increasingly used in cochlear implant (CI) surgery, in order to monitor the effect of insertion of the electrode array aiming to preserve residual hearing. However, obtained results are often difficult to interpret. Here we aim to relate changes in ECochG responses to acute trauma induced by different stages of cochlear implantation by performing ECochG at multiple time points during the procedure in normal-hearing guinea pigs. Materials and methods Eleven normal-hearing guinea pigs received a gold-ball electrode that was fixed in the round-window niche. ECochG recordings were performed during the four steps of cochlear implantation using the gold-ball electrode: (1) Bullostomy to expose the round window, (2) hand-drilling of 0.5-0.6 mm cochleostomy in the basal turn near the round window, (3) insertion of a short flexible electrode array, and (4) withdrawal of electrode array. Acoustical stimuli were tones varying in frequency (0.25-16 kHz) and sound level. The ECochG signal was primarily analyzed in terms of threshold, amplitude, and latency of the compound action potential (CAP). Midmodiolar sections of the implanted cochleas were analyzed in terms of trauma to hair cells, modiolar wall, osseous spiral lamina (OSL) and lateral wall. Results Animals were assigned to cochlear trauma categories: minimal (n = 3), moderate (n = 5), or severe (n = 3). After cochleostomy and array insertion, CAP threshold shifts increased with trauma severity. At each stage a threshold shift at high frequencies (4-16 kHz) was accompanied with a threshold shift at low frequencies (0.25-2 kHz) that was 10-20 dB smaller. Withdrawal of the array led to a further worsening of responses, which probably indicates that insertion and removal trauma affected the responses rather than the mere presence of the array. In two instances, CAP threshold shifts were considerably larger than threshold shifts of cochlear microphonics, which could be explained by neural damage due to OSL fracture. A change in amplitudes at high sound levels was strongly correlated with threshold shifts, which is relevant for clinical ECochG performed at one sound level. Conclusion Basal trauma caused by cochleostomy and/or array insertion should be minimized in order to preserve the low-frequency residual hearing of CI recipients.
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Affiliation(s)
- Saad Jwair
- Department of Otorhinolaryngology and Head and Neck Surgery, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands,UMC Utrecht Brain Center, Utrecht University, Utrecht, Netherlands
| | - Dyan Ramekers
- Department of Otorhinolaryngology and Head and Neck Surgery, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands,UMC Utrecht Brain Center, Utrecht University, Utrecht, Netherlands
| | - Hans G. X. M. Thomeer
- Department of Otorhinolaryngology and Head and Neck Surgery, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands,UMC Utrecht Brain Center, Utrecht University, Utrecht, Netherlands
| | - Huib Versnel
- Department of Otorhinolaryngology and Head and Neck Surgery, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands,UMC Utrecht Brain Center, Utrecht University, Utrecht, Netherlands,*Correspondence: Huib Versnel,
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Morphological and Morphometrical Aspects of the Auditory Ossicles in the European Badger (Meles Meles). Vet Sci 2022; 9:vetsci9090483. [PMID: 36136699 PMCID: PMC9504775 DOI: 10.3390/vetsci9090483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 09/05/2022] [Accepted: 09/07/2022] [Indexed: 11/30/2022] Open
Abstract
Simple Summary The little-described morphology of the ear ossicles in the badger provides some interesting morphological features alongside some metrical data. For the malleus, we notice the standard framing into the known shape, with the mentioned presence at the level of the column of all three processes (lateral, rostral and medial), from which the rostral one is the most developed. The malleal manubrium is long and triangularly shaped on a cross-section. For the incus we notice the overall shape of a biradicular molar with the existence of the two crura in acute angulation, while the long crus is continuing with the lenticular process. The presence of a bony blade that links to the lenticular process is also noted. For the stapes, the almost equal two crura and the quite round intercrural foramen is described. Abstract Given the scarce morphological data regarding the middle ear anatomy of this species, the paper attempts to describe the morphological and morphometrical data of the auditory ossicles in the badger. The study was performed using the standard morphological investigations and provides a complete morphological description of the ossicular assembly (malleus, incus and stapes) with some comparative features and attempts to provide a complete set of standardized metrical data for each ossicle. A more-detailed attempt to compare some functional aspects in the light of combined metrical ratios is also implied.
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Trinh TT, Cohen C, Boullaud L, Cottier JP, Bakhos D. Sheep as a large animal model for cochlear implantation. Braz J Otorhinolaryngol 2021; 88 Suppl 1:S24-S32. [PMID: 33839060 PMCID: PMC9734264 DOI: 10.1016/j.bjorl.2021.02.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 01/15/2021] [Accepted: 02/28/2021] [Indexed: 12/16/2022] Open
Abstract
INTRODUCTION In surgical training, large animal models are more suitable as their anatomy is more similar to humans. In otology, there have been relatively few studies about large animal models for surgical training. OBJECTIVE In this study, we aimed to do a neuroradiologic evaluation and surgical insertion of a cochlear implant electrode array on a sheep head model. METHODS Twenty cadaveric sheep heads were studied. A computed tomography scan and neuroradiologic evaluation was performed on each head, obtaining measurements of the inner ear for each sheep. Sheep measurements were compared to those from temporal bone computed tomography scans from 20 female humans. Surgical procedures were first trained with 13 of the sheep temporal bones, after which cochlear implantation was performed on the remaining 7 temporal bones. The position of the inserted electrode array insertion was confirmed by computed tomography scan after the procedure. RESULTS Neuroradiologic evaluation showed that, relative to the 20 female humans, the mean ratio for sheep was 0.60 for volume of cochlea, 0.70 for height of cochlea, 0.73 for length of cochlea; ratios for other metrics were >0.80. For the surgical training, the round window was found in all 20 sheep temporal bones. Computed tomography scans confirmed that electrode insertions were fully complete; the mean value of electrode array insertion was 18.3 mm. CONCLUSION The neuroradiologic and surgical training data suggest that the sheep is a realistic animal model to train cochlear implant surgery and collection of perilymph samples, but less so for surgical training of mastoidectomy due to pneumatization of the mastoid.
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Affiliation(s)
- Thuy-Tran Trinh
- CHRU de Tours, Service d'ORL et Chirurgie Cervico-Faciale, France.
| | - C Cohen
- CHRU de Tours, Service de Neuroradiologie, France
| | - L Boullaud
- CHRU de Tours, Service d'ORL et Chirurgie Cervico-Faciale, France
| | - J P Cottier
- CHRU de Tours, Service de Neuroradiologie, France; Université François Rabelais de Tours, France; Inserm U1253, Tours, France
| | - David Bakhos
- CHRU de Tours, Service d'ORL et Chirurgie Cervico-Faciale, France; Université François Rabelais de Tours, France; Inserm U1253, Tours, France
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Li Q, Chen M, Zhang C, Lu T, Min S, Li S. Opposite Roles of NT-3 and BDNF in Synaptic Remodeling of the Inner Ear Induced by Electrical Stimulation. Cell Mol Neurobiol 2020; 41:1665-1682. [PMID: 32770528 DOI: 10.1007/s10571-020-00935-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 08/01/2020] [Indexed: 12/11/2022]
Abstract
With the development of neural prostheses, neural plasticity including synaptic remodeling under electrical stimulation is drawing more and more attention. Indeed, intracochlear electrical stimulation used to restore hearing in deaf can induce the loss of residual hearing and synapses of the inner hair cells (IHCs). However, the mechanism under this process is largely unknown. Considering that the guinea pig is always a suitable and convenient choice for the animal model of cochlea implant (CI), in the present study, normal-hearing guinea pigs were implanted with CIs. Four-hour electrical stimulation with the intensity of 6 dB above electrically evoked compound action potential (ECAP) threshold (which can decrease the quantity of IHC synapses and the excitability of the auditory nerve) resulted in the upregulation of Bdnf (p < 0.0001) and downregulation of Nt-3 (p < 0.05). Intracochlear perfusion of exogenous NT-3 or TrkC/Fc (which blocks NT-3) can, respectively, resist or aggravate the synaptic loss induced by electrical stimulation. In contrast, local delivery of exogenous BDNF or TrkB/Fc (which blocks BDNF) to the cochlea, respectively, exacerbated or protected against the synaptic loss caused by electrical stimulation. Notably, the synaptic changes were only observed in the basal and middle halves of the cochlea. All the findings above suggested that NT-3 and BDNF may play opposite roles in the remodeling of IHC synapses induced by intracochlear electrical stimulation, i.e. NT-3 and BDNF promoted the regeneration and degeneration of IHC synapses, respectively.
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Affiliation(s)
- Qiang Li
- ENT Institute and Department of Otolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, China
| | - Min Chen
- ENT Institute and Department of Otolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, China
| | - Chen Zhang
- ENT Institute and Department of Otolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, China
| | - Tianhao Lu
- ENT Institute and Department of Otolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, China
| | - Shiyao Min
- ENT Institute and Department of Otolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, China
| | - Shufeng Li
- ENT Institute and Department of Otolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China. .,NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, China.
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Anatomical and Functional Consequences of Microneedle Perforation of Round Window Membrane. Otol Neurotol 2020; 41:e280-e287. [DOI: 10.1097/mao.0000000000002491] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Honeder C, Zhu C, Gausterer JC, Schöpper H, Ahmadi N, Saidov N, Nieratschker M, Gabor F, Arnoldner C. Sustained-Release Triamcinolone Acetonide Hydrogels Reduce Hearing Threshold Shifts in a Model for Cochlear Implantation with Hearing Preservation. Audiol Neurootol 2019; 24:237-244. [PMID: 31574511 DOI: 10.1159/000501331] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 06/04/2019] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION In recent years, the preservation of residual hearing has become a major factor in patients undergoing cochlear implantation (CI). In studies attempting to pharmaceutically improve hearing preservation rates, glucocorticoids (GCs) applied perioperatively in many institutions have emerged as a promising treatment regimen. Although dexamethasone is most commonly used and has been applied successfully by various research groups, recently pharmacological properties have been reported to be relatively unsuitable for topical delivery to the inner ear. Consequently other glucocorticoids merit further evaluation. The aim of this study was therefore to evaluate the otoprotective effects of the topical application of a sustained-release triamcinolone acetonide (TAAC) hydrogel in CI with hearing preservation. METHODS Normal-hearing pigmented guinea pigs were randomized into a group receiving a single dose of a 6% TAAC poloxamer 407 hydrogel, a group receiving a 30% TAAC hydrogel and a control group. All hydrogel applications were performed 1 day prior to CI. After a cochleostomy was drilled, a specifically designed silicone electrode was inserted into the scala tympani for 5 mm. Frequency-specific compound action potentials of the auditory nerve (0.5-32 kHz) were measured pre- and directly postoperatively as well as on days 3, 7, 14, 21, and 28. Finally, temporal bones were harvested for histological evaluation. RESULTS Application of the TAAC hydrogels resulted in significantly reduced hearing threshold shifts in low, middle and high frequencies and improved spiral ganglion cell survival in the second turn of the cochlea. Outer hair cell numbers in the basal and second turn of the cochlea were slightly reduced after TAAC application. CONCLUSION In summary, we were able to demonstrate functional benefits of a single preoperative application of a TAAC hydrogel in a guinea pig model for CI, which persisted until the end of the observational period, that is, 28 days after surgery.
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Affiliation(s)
- Clemens Honeder
- Department of Otorhinolaryngology, Medical University of Vienna, Vienna, Austria
| | - Chengjing Zhu
- Department of Otorhinolaryngology, Medical University of Vienna, Vienna, Austria
| | - Julia Clara Gausterer
- Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, Vienna, Austria
| | - Hanna Schöpper
- Department of Pathobiology, Institute of Anatomy, Histology and Embryology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Navid Ahmadi
- Department of Otorhinolaryngology, Medical University of Vienna, Vienna, Austria
| | - Nodir Saidov
- Department of Otorhinolaryngology, Medical University of Vienna, Vienna, Austria
| | - Michael Nieratschker
- Department of Otorhinolaryngology, Medical University of Vienna, Vienna, Austria
| | - Franz Gabor
- Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, Vienna, Austria,
| | - Christoph Arnoldner
- Department of Otorhinolaryngology, Medical University of Vienna, Vienna, Austria
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