scholarly journals Neural Tissue Degeneration in Rosenthal’s Canal and Its Impact on Electrical Stimulation of the Auditory Nerve by Cochlear Implants: An Image-Based Modeling Study

2020 ◽  
Vol 21 (22) ◽  
pp. 8511
Author(s):  
Kiran Kumar Sriperumbudur ◽  
Revathi Appali ◽  
Anthony W. Gummer ◽  
Ursula van Rienen
Keyword(s):  
Cochlear Implant ◽  
Cochlear Implants ◽  
Auditory Nerve ◽  
Ganglion Cells ◽  
Spiral Ganglion ◽  
Sensorineural Deafness ◽  
Neural Tissue ◽  
Neural Degeneration ◽  
Tissue Degeneration ◽  
Ganglion Neurons

Sensorineural deafness is caused by the loss of peripheral neural input to the auditory nerve, which may result from peripheral neural degeneration and/or a loss of inner hair cells. Provided spiral ganglion cells and their central processes are patent, cochlear implants can be used to electrically stimulate the auditory nerve to facilitate hearing in the deaf or severely hard-of-hearing. Neural degeneration is a crucial impediment to the functional success of a cochlear implant. The present, first-of-its-kind two-dimensional finite-element model investigates how the depletion of neural tissues might alter the electrically induced transmembrane potential of spiral ganglion neurons. The study suggests that even as little as 10% of neural tissue degeneration could lead to a disproportionate change in the stimulation profile of the auditory nerve. This result implies that apart from encapsulation layer formation around the cochlear implant electrode, tissue degeneration could also be an essential reason for the apparent inconsistencies in the functionality of cochlear implants.

scholarly journals Meta-Analysis—Correlation between Spiral Ganglion Cell Counts and Speech Perception with a Cochlear Implant

2021 ◽  
Vol 11 (2) ◽  
pp. 220-226
Author(s):  
Yew-Song Cheng ◽  
Mario A. Svirsky
Keyword(s):  
Speech Perception ◽  
Cochlear Implant ◽  
Ganglion Cells ◽  
Meta Analysis ◽  
Spiral Ganglion ◽  
Spiral Ganglion Cell ◽  
Cell Counts ◽  
Temporal Bones ◽  
The Relationship ◽  
Existing Data

The presence of spiral ganglion cells (SGCs) is widely accepted to be a prerequisite for successful speech perception with a cochlear implant (CI), because SGCs provide the only known conduit between the implant electrode and the central auditory system. By extension, it has been hypothesized that the number of SGCs might be an important factor in CI outcomes. An impressive body of work has been published on findings from the laborious process of collecting temporal bones from CI users and counting the number of SGCs to correlate those numbers with speech perception scores, but the findings thus far have been conflicting. We performed a meta-analysis of all published studies with the hope that combining existing data may help us reach a more definitive conclusion about the relationship between SGC count and speech perception scores in adults.

Brn3a is a transcriptional regulator of soma size, target field innervation and axon pathfinding of inner ear sensory neurons

Development ◽  
2001 ◽  
Vol 128 (13) ◽  
pp. 2421-2432 ◽  
Author(s):  
Eric J. Huang ◽  
Wei Liu ◽  
Bernd Fritzsch ◽  
Lynne M. Bianchi ◽  
Louis F. Reichardt ◽  
...  
Keyword(s):  
Inner Ear ◽  
Ganglion Cells ◽  
Substantial Reduction ◽  
Spiral Ganglion ◽  
Neurotrophin Receptor ◽  
Axon Pathfinding ◽  
Target Field ◽  
Afferent Fibers ◽  
Soma Size ◽  
Ganglion Neurons

The POU domain transcription factors Brn3a, Brn3b and Brn3c are required for the proper development of sensory ganglia, retinal ganglion cells, and inner ear hair cells, respectively. We have investigated the roles of Brn3a in neuronal differentiation and target innervation in the facial-stato-acoustic ganglion. We show that absence of Brn3a results in a substantial reduction in neuronal size, abnormal neuronal migration and downregulation of gene expression, including that of the neurotrophin receptor TrkC, parvalbumin and Brn3b. Selective loss of TrkC neurons in the spiral ganglion of Brn3a−/− cochlea leads to an innervation defect similar to that of TrkC−/− mice. Most remarkably, our results uncover a novel role for Brn3a in regulating axon pathfinding and target field innervation by spiral and vestibular ganglion neurons. Loss of Brn3a results in severe retardation in development of the axon projections to the cochlea and the posterior vertical canal as early as E13.5. In addition, efferent axons that use the afferent fibers as a scaffold during pathfinding also show severe misrouting. Interestingly, despite the well-established roles of ephrins and EphB receptors in axon pathfinding, expression of these molecules does not appear to be affected in Brn3a−/− mice. Thus, Brn3a must control additional downstream genes that are required for axon pathfinding.

scholarly journals Comparison of Methods for the Histological Evaluation of Odontocete Spiral Ganglion Cells

Animals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 683 ◽  
Author(s):  
Tania Ramírez ◽  
Simona Sacchini ◽  
Yania Paz ◽  
Rubén S. Rosales ◽  
Nakita Câmara ◽  
...  
Keyword(s):  
Cell Morphology ◽  
Ganglion Cells ◽  
Spiral Ganglion ◽  
Auditory Pathway ◽  
Histological Evaluation ◽  
Anatomical Location ◽  
Tissue Samples ◽  
Edta Solution ◽  
Ganglion Neurons ◽  
Hearing System

Cetaceans greatly depend on their hearing system to perform many vital activities. The spiral ganglion is an essential component of the auditory pathway and can even be associated with injuries caused by anthropogenic noise. However, its anatomical location, characterized by surrounding bony structures, makes the anatomical and anatomopathological study of the spiral ganglion a difficult task. In order to obtain high-quality tissue samples, a perfect balance between decalcification and the preservation of neural components must be achieved. In this study, different methodologies for spiral ganglion sample preparation and preservation were evaluated. Hydrochloric acid had the shortest decalcification time but damaged the tissue extensively. Both formic acid and EDTA decalcification solutions had a longer decalcification time but exhibited better preservation of the neurons. However, improved cell morphology and staining were observed on ears pretreated with EDTA solution. Therefore, we suggest that decalcifying methodologies based on EDTA solutions should be used to obtain the highest quality samples for studying cell morphology and antigenicity in cetacean spiral ganglion neurons.

scholarly journals Intrinsically Self-renewing Neuroprogenitors From the A/J Mouse Spiral Ganglion as Virtually Unlimited Source of Mature Auditory Neurons

2020 ◽  
Vol 14 ◽  
Author(s):  
Francis Rousset ◽  
Vivianne B. C. Kokje ◽  
Rebecca Sipione ◽  
Dominik Schmidbauer ◽  
German Nacher-Soler ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Inner Ear ◽  
Progenitor Cells ◽  
Ganglion Cells ◽  
Spiral Ganglion ◽  
Specific Cell ◽  
Auditory Neurons ◽  
Self Renewal ◽  
Starting Point ◽  
Ganglion Neurons

Nearly 460 million individuals are affected by sensorineural hearing loss (SNHL), one of the most common human sensory disorders. In mammals, hearing loss is permanent due to the lack of efficient regenerative capacity of the sensory epithelia and spiral ganglion neurons (SGN). Sphere-forming progenitor cells can be isolated from the mammalian inner ear and give rise to inner ear specific cell types in vitro. However, the self-renewing capacities of auditory progenitor cells from the sensory and neuronal compartment are limited to few passages, even after adding powerful growth factor cocktails. Here, we provide phenotypical and functional characterization of a new pool of auditory progenitors as sustainable source for sphere-derived auditory neurons. The so-called phoenix auditory neuroprogenitors, isolated from the A/J mouse spiral ganglion, exhibit robust intrinsic self-renewal properties beyond 40 passages. At any passage or freezing–thawing cycle, phoenix spheres can be efficiently differentiated into mature spiral ganglion cells by withdrawing growth factors. The differentiated cells express both neuronal and glial cell phenotypic markers and exhibit similar functional properties as mouse spiral ganglion primary explants and human sphere-derived spiral ganglion cells. In contrast to other rodent models aiming at sustained production of auditory neurons, no genetic transformation of the progenitors is needed. Phoenix spheres therefore represent an interesting starting point to further investigate self-renewal in the mammalian inner ear, which is still far from any clinical application. In the meantime, phoenix spheres already offer an unlimited source of mammalian auditory neurons for high-throughput screens while substantially reducing the numbers of animals needed.

scholarly journals Spatiotemporal Developmental Upregulation of Prestin Correlates With the Severity and Location of Cyclodextrin-Induced Outer Hair Cell Loss and Hearing Loss

2021 ◽  
Vol 9 ◽  
Author(s):  
Dalian Ding ◽  
Haiyan Jiang ◽  
Senthilvelan Manohar ◽  
Xiaopeng Liu ◽  
Li Li ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Hair Cells ◽  
Auditory Nerve ◽  
High Frequency ◽  
Spiral Ganglion ◽  
Low Frequency ◽  
Nerve Fibers ◽  
Spiral Ganglion Neurons ◽  
Auditory Nerve Fibers ◽  
Ganglion Neurons

2-Hyroxypropyl-beta-cyclodextrin (HPβCD) is being used to treat Niemann-Pick C1, a fatal neurodegenerative disease caused by abnormal cholesterol metabolism. HPβCD slows disease progression, but unfortunately causes severe, rapid onset hearing loss by destroying the outer hair cells (OHC). HPβCD-induced damage is believed to be related to the expression of prestin in OHCs. Because prestin is postnatally upregulated from the cochlear base toward the apex, we hypothesized that HPβCD ototoxicity would spread from the high-frequency base toward the low-frequency apex of the cochlea. Consistent with this hypothesis, cochlear hearing impairments and OHC loss rapidly spread from the high-frequency base toward the low-frequency apex of the cochlea when HPβCD administration shifted from postnatal day 3 (P3) to P28. HPβCD-induced histopathologies were initially confined to the OHCs, but between 4- and 6-weeks post-treatment, there was an unexpected, rapid and massive expansion of the lesion to include most inner hair cells (IHC), pillar cells (PC), peripheral auditory nerve fibers, and spiral ganglion neurons at location where OHCs were missing. The magnitude and spatial extent of HPβCD-induced OHC death was tightly correlated with the postnatal day when HPβCD was administered which coincided with the spatiotemporal upregulation of prestin in OHCs. A second, massive wave of degeneration involving IHCs, PC, auditory nerve fibers and spiral ganglion neurons abruptly emerged 4–6 weeks post-HPβCD treatment. This secondary wave of degeneration combined with the initial OHC loss results in a profound, irreversible hearing loss.

scholarly journals Auditory responses evoked by optical stimulation on the optogenetic-infected cochlear neurons in the guinea pigs

2020 ◽  
Author(s):  
Chen Liu ◽  
Shu Fang ◽  
Da-xiong Ding ◽  
Han-dai Qin ◽  
Shuo-long Yuan ◽  
...  
Keyword(s):  
Cochlear Implants ◽  
Guinea Pigs ◽  
Spiral Ganglion ◽  
Acoustic Stimulation ◽  
Electrophysiological Recording ◽  
Gene Encoding ◽  
Auditory Responses ◽  
Sensorineural Hearing Impairment ◽  
Cochlear Neurons ◽  
Ganglion Neurons

AbstractCochlear implants (CIs) are by far the optimal option to partially restore hearing for the patients of sensorineural hearing impairment (HI) by electrically stimulating spiral ganglion neurons (SGNs). However, wide current spread from each electrode constitute an interface which restricts precision and quality of the electrical CIs. Recently, optogenetic stimulation of the cochlea has been proved as a more optimized approach via adeno-associated virus (AAV) carrying the gene encoding the light-sensitive channelrhodopsin-2. Here, we focus on summarizing recent work on stable and accurate ChR2 expression and compare the electrophysiological recording of optogenetic and acoustic stimulation in adult guinea pigs. Light stimulation generated auditory responses that was similar to that of acoustic stimulation. Moreover, normal hearing adult guinea pigs responded with a rise in amplitudes with increasing light intensity. In conclusion, optogenetic cochlear stimulation achieved good spectral selectivity of artificial sound encoding in a new adult rodent model, suggesting that the capabilities of optogenetics might be applied to improve cochlear implants in the future.

Multi-channel cochlear implant histopathology: Are fewer spiral ganglion cells really related to better clinical performance?

2012 ◽  
Vol 132 (5) ◽  
pp. 482-490 ◽  
Author(s):  
Helen X. Xu ◽  
Grace H. Kim ◽  
Eugene P. Snissarenko ◽  
Sebahattin Cureoglu ◽  
Michael M. Paparella
Keyword(s):  
Cochlear Implant ◽  
Ganglion Cells ◽  
Clinical Performance ◽  
Spiral Ganglion

scholarly journals Vestibular dysfunction and postural balance in cochlear implant users: a narrative literature review

Revista CEFAC ◽  
2018 ◽  
Vol 20 (1) ◽  
pp. 101-109
Author(s):  
Juliana Jandre Melo ◽  
Paula Carolina Dias Gibrin ◽  
Luciana Lozza de Moraes Marchiori
Keyword(s):  
Cochlear Implant ◽  
Auditory Nerve ◽  
Postural Balance ◽  
Ganglion Cells ◽  
Vestibular Function ◽  
Electrical Current ◽  
Nerve Fibers ◽  
Vestibular Dysfunction ◽  
Speech Comprehension ◽  
Profound Hearing Loss

ABSTRACT Cochlear implants directly stimulate nerve fibers and ganglion cells of the auditory nerve, which transform sound energy into low levels of electrical current, stimulating the remaining fibers of the auditory nerve in patients with severe to profound hearing loss, in order to provide the significant range of auditory sensation and speech comprehension. Due to the close relationship between cochlea and vestibular receptors, some patients may present vestibular and postural balance changes concomitantly after surgery. This study aimed to perform a narrative review of the main studies that relate vestibular symptoms in patients implanted in the last six years. The research was performed through the databases: SciELO, LILACS and PubMed, using associated descriptors for "cochlear implant", "vestibular dysfunction", "vertigo" and "balance", totalizing 21 studies that fitted the inclusion criteria. The results were described in a chronological order of publication, showing the main conclusions. Of the total studies analyzed, 18 related vestibular function to cochlear implant and only 3 studies did not find such a relationship. The literature characterize the effects of the cochlear implant on the vestibular system, however, the results are contradictory.

Age- and Condition-Related Changes in Levels of Neuron Specific Enolase in Spiral Ganglion Neurons of C57BL/6 Mice

1998 ◽  
Vol 4 (S2) ◽  
pp. 1106-1107
Author(s):  
Glenn M. Cohen
Keyword(s):  
Hair Cells ◽  
Auditory Nerve ◽  
Nervous Tissue ◽  
Spiral Ganglion ◽  
Neuron Specific Enolase ◽  
Nerve Degeneration ◽  
Spiral Ganglion Neurons ◽  
Cacodylate Buffer ◽  
Lower Temperature ◽  
Ganglion Neurons

The mouse strain C57BL/6 suffers from the early onset of deafness. The deafness is attributable to sweeping degeneration of hair cells and the auditory nerve. Degeneration advances with age from the base to the apex of the cochlea. In the present study, neuronal condition was determined by linking relative levels of neuron specific enolase (NSE) in spiral ganglion neurons to their cytological appearances. NSE is an enolase isoform that is expressed only in nervous tissue and neuroendocrine glands.Mice ranged in age from 3 days to 10 months. Inner ears were fixed with 2.5% paraformaldehyde in 0.1 M cacodylate buffer, decalcified for 24 hrs with EDTA, and then embedded in either paraffin or polyester wax. The latter, which melts at a lower temperature, caused much less neuronal shrinkage during routine processing. Deparaffinized sections were exposed first to rabbit anti-bovine NSE antibodies, then to biotinylated swine anti-rabbit antibodies, and finally to peroxidase-labelled avidin.

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