SPECIAL ARTICLES   

Otorinolaringologia 2016 September;66(3):93-8

Copyright © 2016 EDIZIONI MINERVA MEDICA

language: English

Membrane mechanical advantage and its role in endolymphatic hydrops

Daniel J. PENDER

Department of Otolaryngology, Columbia University Medical Center, New York City, NY, USA

In endolymphatic hydrops, the various chambers of the labyrinth do not distend uniformly, with the pars inferior the more affected. This implies that some membrane areas are more resistant to distention to others. The less affected areas may be construed to enjoy a mechanical advantage over the more affected areas. In order to better understand how such membrane mechanical advantage (MMA) functions, a quantitative method of evaluation is needed. MMA can be evaluated using a model of the human vestibular labyrinth that employs axially symmetric spheroidal chambers that are mathematically tractable. The ampulla is modeled as a prolate spheroid while the saccule is modeled as an oblate spheroid. Based on the model, the ampulla is calculated to enjoy an 18:1 mechanical advantage over the saccule. This suggests that the initial distention of the saccule in hydrops will be 18 fold that of the ampulla. The concept of MMA is a new way to understand how some sectors in a complex membrane system such as the labyrinth can enjoy a privileged status in their reaction to a uniform transmural pressure.