Relationships between Intrascalar Tissue, Neuron Survival, and Cochlear Implant Function
- PDF / 1,957,590 Bytes
- 16 Pages / 595.276 x 790.866 pts Page_size
- 31 Downloads / 202 Views
JARO (2020) DOI: 10.1007/s10162-020-00761-4 D 2020 Association for Research in Otolaryngology
Research Article
Journal of the Association for Research in Otolaryngology
Relationships between Intrascalar Tissue, Neuron Survival, and Cochlear Implant Function DONALD L. SWIDERSKI,1 DEBORAH J. COLESA,1 AARON P. HUGHES,1 YEHOASH RAPHAEL,1 BRYAN E. PFINGST1
AND
1
Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA Received: 23 December 2019; Accepted: 12 July 2020
ABSTRACT
INTRODUCTION
Fibrous tissue and/or new bone are often found surrounding a cochlear implant in the cochlear scalae. This new intrascalar tissue could potentially limit cochlear implant function by increasing impedance and altering signaling pathways between the implant and the auditory nerve. In this study, we investigated the relationship between intrascalar tissue and 5 measures of implant function in guinea pigs. Variation in both spiral ganglion neuron (SGN) survival and intrascalar tissue was produced by implanting hearing ears, ears deafened with neomycin, and neomycin-deafened ears treated with a neurotrophin. We found significant effects of SGN density on 4 functional measures but adding intrascalar tissue level to the analysis did not explain more variation in any measure than was explained by SGN density alone. These results suggest that effects of intrascalar tissue on electrical hearing are relatively unimportant in comparison to degeneration of the auditory nerve, although additional studies in human implant recipients are still needed to assess the effects of this tissue on complex hearing tasks like speech perception. The results also suggest that efforts to minimize the trauma that aggravates both tissue development and SGN loss could be beneficial.
Many recipients of cochlear implants (CIs) demonstrate remarkable recovery of hearing, but others do not (Blamey et al. 1992; Moberly et al. 2016). Patients also exhibit differences in hearing between stimulation sites (electrodes) within ears (Zwolan et al. 1997; Garadat et al. 2012; Schvartz-Leyzac and Pfingst 2016). Because the purpose of the CI is to stimulate the auditory nerve (Clark et al. 1984; Hochmair and Hochmair-Desoyer 1981), variation in survival of spiral ganglion neurons (SGNs) has been proposed to explain variation in patients’ hearing with a CI (Parkins 1985; Blamey et al. 1992). Some studies have supported this hypothesis (Zhou and Pfingst 2014; Seyyedi et al. 2014; Kamakura and Nadol 2016; Pfingst et al. 2017; Schvartz-Leyzac and Pfingst 2018) but others have not (Khan et al. 2005; Fayad and Linthicum 2006). Furthermore, the studies showing that variation in SGN density explains some of the variation in CI function also show that much of the variation in function remains unexplained (Kamakura and Nadol 2016; Pfingst et al. 2011, 2017). Other factors proposed to contribute to the unexplained variability in CI function include patient age and cognitive function at impla
Data Loading...
