Suspensory Tethers and Critical Point Membrane Displacement in Endolymphatic Hydrops

Abstract

Introduction Grossly displaced membranes are characteristic of endolymphatic hydrops. The process whereby physiological membrane displacement becomes pathological may be mediated by stress, but the membrane biomechanics underlying this transition are unclear.

Objective This study seeks to determine the role of suspensory tethers during pressure-induced membrane displacement in the generation of the membranous lesions seen in this disease entity using a biomechanical model approach.

Methods The location of membrane suspensory tethers was identified histologically. The influence of tethers on model membrane configuration during displacement was assessed graphically. The relationship of membrane configuration during displacement to curvature radius was quantified trigonometrically. The relationship of curvature radius to stress susceptibility was determined mathematically. The net effect of suspensory tethers on membrane stress levels for various degrees of membrane distention and displacement was then calculated numerically.

Results In the inferior labyrinth, suspensory tethers are found to occur on the membranes' boundaries. Such tethering is found to impose a biphasic effect on membrane curvature with increasing degrees of displacement. As a consequence, tensile stress susceptibility is found to decline with initial membrane displacement to a critical point nadir beyond which stress then increases monotonically. No such effect was found for the superior labyrinth.

Conclusion Boundary tethers in the inferior labyrinth are associated with significant tensile stress reductions until a critical point of membrane displacement is reached. Displacements short of the critical point may be physiological and even reversible, whereas such displacements beyond the critical point are apt to be overtly hydropic and irreversible.

Keywords

endolymphatic hydrops - membranes - rupture

• References

• 1 Schuknecht HA. Pathology of the Ear. Cambridge: Harvard University Press; 1974
• 2 Pender DJ. A model analysis of static stress in the vestibular membranes. Theor Biol Med Model 2009; 6: 19
• 3 Nomura Y. Morphological Aspects of Inner Ear Disease. Tokyo: Springer; 2014
• 4 Pender DJ. A model design for the labyrinthine membranes in mammals. Laryngoscope 2014; 124 (06) E245-E249
• 5 Pender DJ. Membrane stress proclivities in the Mammalian labyrinth. Int Arch Otorhinolaryngol 2014; 18 (04) 398-402
• 6 Avery ME, Mead J. Surface properties in relation to atelectasis and hyaline membrane disease. AMA J Dis Child 1959; 97 (5, Part 1): 517-523
• 7 Schuknecht HF, Gulya AJ. Endolymphatic hydrops. An overview and classification. Ann Otol Rhinol Laryngol Suppl 1983; 106: 1-20
• 8 Pender DJ. Endolymphatic hydrops and Ménière's disease: a lesion meta-analysis. J Laryngol Otol 2014; 128 (10) 859-865
• 9 Antoli-Candela F. The Histopathology of Meniere's Disease. Acta Otolaryngol 1976; 340: 1-42
• 10 Pender DJ. Membrane mechanical advantage and its role in endolymphatic hydrops. Otorinolaringologia 2016; 66 (03) 93-98