The Effect of Collagen Viscoelastoplasiticty on Reissner’s Membrane Displacement: A Graphic Analysis

Background: The aim of this study is to analyze the effect of collagen viscoelastoplasticity on the bulge displacement of Reissner’s membrane that is observed in endolymphatic hydrops and Meniere’s disease. Methods: Viscoelastoplastic load–deformation characteristics for Reissner’s membrane were based on a reported collagen polymer model of the cochleo-saccular membranes. The projected bulge displacements of Reissner’s model membrane at key distention points were quantified trigonometrically and plotted graphically. Results: Initial deformation is characterized by a membrane laxity with substantial stretch at low tension with projected bulge displacement of Reissner’s membrane approaching 30%. Intermediate deformation is characterized by a linear membrane stiffness with projected bulge displacement of Reissner’s membrane in the range of 30-40%. Terminal deformation is characterized by reduced stiffness with a disproportionate increase in membrane stretch with projected bulge displacement of Reissner’s membrane reaching a critical value of 50%, indicating a hemi-circular profile with imminent risk of rupture. Conclusion: This collagen model of membrane viscoelastoplasticity demonstrates that at low pressure significant degrees of bulge displacement up to 30% can occur that may be reversible. The narrower 30-40% range of membrane displacement is one of the increasing deformity but without risk of rupture. Greater displacements approaching 50% indicate that the membrane is reaching a critical hemi-circular configuration with impending rupture.