Importance of cochlear health for implant function

Pfingst, Bryan E.; Zhou, Ning; Colesa, Deborah J.; Watts, Melissa M.; Strahl, Stefan B.; Garadat, Soha N.; Schvartz-Leyzac, Kara C.; Budenz, Cameron L.; Raphael, Yehoash; Zwolan, Teresa A.

doi:10.1016/j.heares.2014.09.009

Cited by 109 publications

(81 citation statements)

References 72 publications

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“…The amplitude of the ECAP response or Wave I of the EABR (typically measured at a high stimulation level), has been shown to largely reflect the function, or health, of the stimulated neurons (Hall, 1990; Shepherd & Javel, 1997). Similarly, others have reported that the slope of the ECAP or Wave 1 ABR AGF is also correlated with SGN density (Smith & Simmons, 1983; Hall, 1990; Pfingst et al, 2014; Ramekers et al, 2014; Pfingst et al, 2015). …”

Section: Introductionmentioning

confidence: 69%

“…Given that (1) ECAPs have been shown to reflect neural health in the animals models (Hall, 1990; Prado-Guitierrez et al, 2006; Ramekers et al, 2014; Pfingst et al, 2015) and (2) neural health degrades as a function of duration of hearing loss in humans (Nadol, 1997) it was of interest to examine the extent to which the duration of hearing loss in each ear prior to undergoing implantation could be accounted for by characteristics of the ECAP response. Results showed a significant, negative correlation between ECAP AGF linear slope for a 7 µs IPG and duration of hearing loss (Figure 11).…”

Section: Discussionmentioning

confidence: 99%

“…Data obtained in the implanted guinea pig suggest that good estimates of SGN density can be obtained during life using ECAP measures (Prado-Guitierrez et al, 2006; Ramekers et al, 2014; Pfingst et al, 2015). These studies reported a significant relationship between SGN density and suprathreshold measures of the ECAP when measured in cochlear-implanted guinea pigs, accounting for 50% of the variance or more in SGN density.…”

Section: Introductionmentioning

confidence: 99%

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Across-site patterns of electrically evoked compound action potential amplitude-growth functions in multichannel cochlear implant recipients and the effects of the interphase gap

Schvartz-Leyzac

Pfingst

2016

Hearing Research

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Electrically evoked compound action potential (ECAP) measures of peak amplitude, and amplitude-growth function (AGF) slope have been shown to reflect characteristics of cochlear health (primarily spiral ganglion density) in anesthetized cochlear-implanted guinea pigs. Likewise, the effect of increasing the interphase gap (IPG) in each of these measures also reflects SGN density in the implanted guinea pig. Based on these findings, we hypothesize that suprathreshold ECAP measures, and also how they change as the IPG is increased, have the potential to be clinically applicable in human subjects. However, further work is first needed in order to determine the characteristics of these measures in humans who use cochlear implants. The current study examined across-site patterns of suprathreshold ECAP measures in 10 bilaterally-implanted, adult cochlear implant users. Results showed that both peak amplitude and slope of the AGF varied significantly from electrode to electrode in ear-specific patterns across the subjects’ electrode arrays. The pattern of across-site performance within each measure (e.g., peak amplitude or slope) varied across subjects and ears. As expected, increasing the IPG on average increased the peak amplitude and slope. Across ears, there was a significant, negative correlation between the slope of the ECAP AGF and the duration of hearing loss. Across-site patterns of ECAP peak amplitude and AGF slopes were also compared with common ground impedance values and significant correlations were observed in some cases, depending on the subject and condition. The results of this study, coupled with previous studies in animals, suggest that it is feasible to measure the change in suprathreshold ECAP measures as the IPG increases on most electrodes. Further work is needed to investigate the relationship between these measures and cochlear implant outcomes, and determine how these measures might be used when programming a cochlear-implant processor.

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Section: Introductionmentioning

confidence: 69%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Across-site patterns of electrically evoked compound action potential amplitude-growth functions in multichannel cochlear implant recipients and the effects of the interphase gap

Schvartz-Leyzac

Pfingst

2016

Hearing Research

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“…101–103 Improving the biological infrastructure of the implanted auditory system could enhance the capacity to receive and process sensory information, allowing more patient-specific stimulation strategies, and might ultimately obviate the need for cochlear implantation. 104 …”

Section: Future Directionsmentioning

confidence: 99%

Neurocognitive factors in sensory restoration of early deafness: a connectome model

Kral

Kronenberger

Pisoni

et al. 2016

The Lancet Neurology

270

240

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Progress in biomedical technology (cochlear, vestibular, and retinal implants) has led to remarkable success in neurosensory restoration, particularly in the auditory system. However, outcomes vary considerably, even after accounting for comorbidity—for example, after cochlear implantation, some deaf children develop spoken language skills approaching those of their hearing peers, whereas other children fail to do so. Here, we review evidence that auditory deprivation has widespread effects on brain development, affecting the capacity to process information beyond the auditory system. After sensory loss and deafness, the brain’s effective connectivity is altered within the auditory system, between sensory systems, and between the auditory system and centres serving higher order neurocognitive functions. As a result, congenital sensory loss could be thought of as a connectome disease, with interindividual variability in the brain’s adaptation to sensory loss underpinning much of the observed variation in outcome of cochlear implantation. Different executive functions, sequential processing, and concept formation are at particular risk in deaf children. A battery of clinical tests can allow early identification of neurocognitive risk factors. Intervention strategies that address these impairments with a personalised approach, taking interindividual variations into account, will further improve outcomes.

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“…We now show that nerve fibers and SVGN survive for a while in the severely traumatized mouse vestibular sensory epithelium, which presents a therapeutic opportunity for a vestibular prosthesis. Although nerve fibers and SVGN do degenerate as time advances after the lesion, it may be possible to preserve nerve terminals and neurons in the FE by stimulating them with a prosthesis, as in the auditory system (Pfingst et al, 2015; Ramekers et al, 2012; Roche et al, 2015). Implanted stem cells and over-expression of neurotrophins (Shibata et al, 2010; Wise et al, 2010) might also be used as adjunct therapies to maintain neural tissue in the vestibular organs.…”

Section: Discussionmentioning

confidence: 99%

Severe streptomycin ototoxicity in the mouse utricle leads to a flat epithelium but the peripheral neural degeneration is delayed

et al. 2017

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The damaged vestibular sensory epithelium of mammals has a limited capacity for spontaneous hair cell regeneration, which largely depends on the transdifferentiation of surviving supporting cells. Little is known about the response of vestibular supporting cells to a severe insult. In the present study, we evaluated the impact of a severe ototoxic insult on the histology of utricular supporting cells and the changes in innervation that ensued. We infused a high dose of streptomycin into the mouse posterior semicircular canal to induce a severe lesion in the utricle. Both scanning electron microscopy and light microscopy of plastic sections showed replacement of the normal cytoarchitecture of the epithelial layer with a flat layer of cells in most of the samples. Immunofluorescence staining showed numerous cells in the severely damaged epithelial layer that were negative for hair cell and supporting cell markers. Nerve fibers under the flat epithelium had high density at the 1 month time point but very low density by 3 months. Similarly, the number of vestibular ganglion neurons was unchanged at 1 month after the lesion, but was significantly lower at 3 months. We therefore determined that the mouse utricular epithelium turns into a flat epithelium after a severe lesion, but the degeneration of neural components is slow, suggesting that treatments to restore balance by hair cell regeneration, stem cell therapy or vestibular prosthesis implantation will likely benefit from the short term preservation of the neural substrate.

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Importance of cochlear health for implant function

Cited by 109 publications

References 72 publications

Across-site patterns of electrically evoked compound action potential amplitude-growth functions in multichannel cochlear implant recipients and the effects of the interphase gap

Across-site patterns of electrically evoked compound action potential amplitude-growth functions in multichannel cochlear implant recipients and the effects of the interphase gap

Neurocognitive factors in sensory restoration of early deafness: a connectome model

Severe streptomycin ototoxicity in the mouse utricle leads to a flat epithelium but the peripheral neural degeneration is delayed

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