Membrane Stress in the Human Labyrinth and Meniere Disease: A Model Analysis

Abstract

Introduction The nature and extent of membrane damage encountered in Meniere disease remains unexplained. Pressure-induced membrane stress may underlie the characteristic hydropic distention. Analysis of stress in the several vestibular chambers may offer insight into the nature and progression of Meniere disease. Objective Membrane stress levels will be assessed by constructing a specific model of the human membranous labyrinth through the application of human dimensions to an existing generic model of the mammalian labyrinth. Methods Nominal dimensions for a model of the human membranous labyrinth were obtained from fixed human tissue. Stress proclivities were calculated and normalized based on shell theory applied to the various geometric figures comprising the model. Results Normalized peak stress levels were projected to be highest in the saccule (38.8), followed by the utricle (5.4), then ampulla (2.4), and lowest in the canal system (1.0). These results reflect macrostructural variations in membrane shape, size, and thickness among the several chambers of the labyrinth. These decreasing stress proclivities parallel the decreasing frequency of histologic lesions found in documented cases of Meniere disease. Conclusions This model analysis of a human membranous labyrinth indicates that substantial disparities in stress exist among the several vestibular chambers due to macrostructural membrane configuration. Low stress levels in the canals are the result of thick highly curved membranes, and the high levels computed for the saccule reflect its thin and relatively flat membranes. These findings suggest that chamber configuration may be a factor controlling the progression of endolymphatic hydrops in Meniere disease.

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“…The walls of the superior labyrinth (utricle and semicircular canals) are thicker than those of the inferior labyrinth (saccule and cochlear), which could explain their relative resistance to mechanical distortion ( 18 , 19 ). Indeed, a mathematical model showed that the SCCs are most resistant to hydropic expansion while the saccule is most vulnerable ( 20 ).…”

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“…Indeed, the resistance to volume increment of an endolymph‐filled closed system would be different according to its geometric configuration and distensibility of the membrane of each structure in the vestibular system. Mathematical model shows that the SCCs are most resistant to hydropic expansion, whereas the saccule is most vulnerable . In addition to the advantage owing to the torus‐shape of the SCCs, the walls of the canals are thicker and more rigid than that of the saccule .…”

“…Mathematical model shows that the SCCs are most resistant to hydropic expansion, whereas the saccule is most vulnerable. 32 In addition to the advantage owing to the torusshape of the SCCs, the walls of the canals are thicker and more rigid than that of the saccule. 33 Because the disease involves the vestibule, the distended vestibule would impair the endolymphatic flow in the SCCs either by mechanical or pressure gradient.…”

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