Editor's Note: This manuscript was accepted for publication February 1, 2008. Accepted for podium presentation at the Triological Society Middle Section Meeting, Chicago, Illinois, January 2008. Supported in part by NIDCD Grant DC006562 and Rainbow Board of Trustees Award.
Spiral Ganglion Degeneration Patterns in Endolymphatic Hydrops†
Article first published online: 2 JAN 2009
Copyright © 2008 The Triological Society
Volume 118, Issue 7, pages 1217–1223, July 2008
How to Cite
Bixenstine, P. J., Maniglia, M. P., Vasanji, A., Alagramam, K. N. and Megerian, C. A. (2008), Spiral Ganglion Degeneration Patterns in Endolymphatic Hydrops. The Laryngoscope, 118: 1217–1223. doi: 10.1097/MLG.0b013e31816ba9cd
- Issue published online: 2 JAN 2009
- Article first published online: 2 JAN 2009
- Endolymphatic hydrops;
- spiral ganglion cell degeneration;
- guinea pig;
- Ménière's disease;
- hearing loss
Objectives: The mechanistic association between endolymphatic hydrops (ELH) and hearing loss (HL) is unclear. Although ELH severity has been shown to correlate in some studies with HL, injury of vital structures, including hair cells and the cochlear nerve, have failed to demonstrate correlation with ELH severity. The goal of this study is to evaluate the hypothesis that spiral ganglion cell degeneration is the principle pathologic site of ELH-related cochlear injury, correlates with ELH severity, and is most profound in the apical region.
Study Design: Surgical induction of ELH in the guinea pig model was followed by histologic confirmation of ELH and subsequent correlation with segmental spiral ganglion cell densities.
Methods: Guinea pigs (N = 14) were subjected to unilateral ELH induction and killed after 4 to 6 months. ELH severity and spiral ganglion densities were obtained using computer-aided morphometric analysis. Densities were normalized by calculating a spiral ganglion degeneration index (DI) for each animal.
Results: The apical spiral ganglion demonstrated significantly greater degeneration than that noted in the basal spiral ganglion (DI: 1.93 vs. 1.13; P = .004). The degree of spiral ganglion degeneration in the apex correlates well with a total hydrops index (P = .006) and an apical hydrops index (P = .003). Basal spiral ganglion degeneration however, does not correlate well with hydrops severity (total hydrops index: P > .05; basilar hydrops index: P > .05).
Conclusions: ELH-related pathology appears to focus initially on the apical spiral ganglion and the degree of deterioration correlates well with the severity of ELH. These findings mirror some reports in the human condition, and imply that the mechanism of cochlear injury in ELH and secondary dysfunction appears to be a neural toxicity that begins in the apex of the cochlea.