Viable spiral ganglion cells in congenital and acquired profound hearing loss

Ghorayer, B.; Sarwat, A; Linthicum, Fred H.

doi:10.1017/s0022215100088952

Cited by 18 publications

(5 citation statements)

References 8 publications

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“…Neuronal degeneration of the spiral ganglion is much slower in humans than in animals. There have been few quantitative studies of remaining SGCs in deaf patients [Kerr and Schuknecht, 1968;Lindsay and Hinojosa, 1978;Otte et al, 1978;Ghorayer et al, 1980;Hinojosa and Marion, 1983;Nadol et al, 1989Nadol et al, , 2001Linthicum and Anderson, 1991;Hinojosa et al, 1995]. Survival rate and speculations on the functionality of SGCs following deafness are discussed here in the light of a temporal bone from a patient who had been deaf for over 50 years as a result of an acoustic trauma in World War II.…”

Section: Introductionmentioning

confidence: 99%

The Human Spiral Ganglion: New Insights into Ultrastructure, Survival Rate and Implications for Cochlear Implants

Glueckert¹,

Pfaller

Kinnefors

et al. 2005

Audiol Neurotol

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This study was based on high-resolution SEM assessment of freshly fixed, normal-hearing, human inner ear tissue. In addition, semiquantitative observations were made in long-term deafened temporal bone material, focusing on the spiral ganglia and nerve projections, and a detailed study of the fine bone structure in macerated tissues was performed. Our main findings detail the presence of extensive bony fenestrae surrounding the nerve elements, permitting a relatively free flow of perilymph to modiolar structures. The clustering of the spiral ganglion cells in Rosenthal’s canal and the detailed and intricate course of postganglionic axons are described. The close proximity of fibers to cell soma is demonstrated by impression in cell surfaces, and presence of small microvilli-like structures at the contact regions, anchoring nerve fibers to the cell wall. Extensive fenestrae and the presence of a fragile network of endosteal bony structures at the surfaces guiding nerve fibers are described in detail for the first time. This unique freshly prepared human material offers the opportunity for a detailed ultrastructural study not previously possible on postmortem fixed material and more accurate information to model electrostimulation of the human auditory nerve through a cochlear implant. On the basis of this study, we suggest that the concentration and high density of spiral ganglion cells, and the close physical interaction between neural elements, may explain the slow retrograde degeneration found in humans after loss of peripheral receptors. Moreover, the fragile bony columns connecting the spiral canal with the osseous spiral lamina may be a potential site for trauma in (perimodiolar) electrode positioning.

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Section: Introductionmentioning

confidence: 99%

The Human Spiral Ganglion: New Insights into Ultrastructure, Survival Rate and Implications for Cochlear Implants

Glueckert¹,

Pfaller

Kinnefors

et al. 2005

Audiol Neurotol

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“…This loss occurs with varying rapidity in different species. For instance in the guinea pig, a substantial abrogation of SGNs is observed 7 days after aminoglycoside treatment ( Kong et al., 2010 ), whereas in human patients, remaining SGNs have been found several decades after hair cell loss is thought to have occurred ( Ghorayer et al., 1980 ).…”

Section: Introductionmentioning

confidence: 99%

Aminoglycoside ototoxicity and hair cell ablation in the adult gerbil: A simple model to study hair cell loss and regeneration

Abbas

Rivolta

2015

Hearing Research

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The Mongolian gerbil, Meriones unguiculatus, has been widely employed as a model for studies of the inner ear. In spite of its established use for auditory research, no robust protocols to induce ototoxic hair cell damage have been developed for this species. In this paper, we demonstrate the development of an aminoglycoside-induced model of hair cell loss, using kanamycin potentiated by the loop diuretic furosemide. Interestingly, we show that the gerbil is relatively insensitive to gentamicin compared to kanamycin, and that bumetanide is ineffective in potentiating the ototoxicity of the drug.We also examine the pathology of the spiral ganglion after chronic, long-term hair cell damage. Remarkably, there is little or no neuronal loss following the ototoxic insult, even at 8 months post-damage. This is similar to the situation often seen in the human, where functioning neurons can persist even decades after hair cell loss, contrasting with the rapid, secondary degeneration found in rats, mice and other small mammals. We propose that the combination of these factors makes the gerbil a good model for ototoxic damage by induced hair cell loss.

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“…Animal studies have shown that SGN degeneration following HC loss may be either gradual [Spoendlin, 1971[Spoendlin, , 1975 or rapid Leake and Hradek, 1988;Zappia and Altschuler, 1989]. Similarly, histological studies of human ears have demonstrated a marked variability between individuals in the extent of SGN loss following HC degeneration [Chen et al, 1998;Fayad et al, 1991;Ghorayer et al, 1980;Linthicum and Anderson, 1991;Nadol, 1997]. Overall, the degeneration of SGNs is probably a result of loss of survival factors [Mattson, 1998], including the lack of depolarizing activity, which is usually provided by the inner HCs [Hansen et al, 2001;Hegarty et al, 1997].…”

Section: Introductionmentioning

confidence: 99%

Adenovirus-Mediated Expression of Brain-Derived Neurotrophic Factor Protects Spiral Ganglion Neurons from Ototoxic Damage

et al. 2004

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Hair cell loss, the most common cause of deafness, is often associated with auditory nerve degeneration. Our goal was to determine the influence of combined ciliary-derived neurotrophic factor (CNTF) and brain-derived neurotrophic factor (BDNF) gene therapy on the survival of spiral ganglion neurons (SGNs) after elimination of inner hair cells in the mature guinea pig ear. Seven days after bilateral deafening, a 5-µl suspension of CNTF and/or BDNF adenovirus vectors was injected into the left scala tympani through the round window. Animals were sacrificed 28 days after deafening, and their inner ears were prepared for SGN counts. The SGN counts revealed that BDNF alone and the combined CNTF and BDNF treatment significantly enhanced SGN survival. CNTF did not significantly enhance the protective effect of BDNF. These data present possible strategies for enhancing SGN survival in cochlear implant procedures.

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Viable spiral ganglion cells in congenital and acquired profound hearing loss

Cited by 18 publications

References 8 publications

The Human Spiral Ganglion: New Insights into Ultrastructure, Survival Rate and Implications for Cochlear Implants

The Human Spiral Ganglion: New Insights into Ultrastructure, Survival Rate and Implications for Cochlear Implants

Aminoglycoside ototoxicity and hair cell ablation in the adult gerbil: A simple model to study hair cell loss and regeneration

Adenovirus-Mediated Expression of Brain-Derived Neurotrophic Factor Protects Spiral Ganglion Neurons from Ototoxic Damage

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