Objective: Structural features of the human cochlea may control early lesion formation in endolymphatic hydrops. This process may hinge on three structural features: the flattened spiral shape of the human cochlea, the toroidal configuration of the distended cochlea duct, and the distensibility characteristics of Reissner's membrane. An analytical method is presented to assess the variation in hydropic distention that may occur in the several turns of the cochlea due to these structural features.
Methods: A normal human cochlea is used to illustrate the method of analysis. Structural dimensions were taken from a mid-modiolar section. Reissner's membrane was projected to assume a spiral toroid shape as it distends. Peak membrane stress proclivities in each cochlea turn were calculated analytically. Membrane strain was assessed from a collagen model of Reissner's membrane. Sagittal membrane displacements were quantified geometrically.
Results: Stress levels in Reissner's membrane were projected to be the lowest in the lower basal turn and to increase progressively to a peak value in the apex. Strain in Reissner's membrane in the apical turn was projected to be substantially higher than in the lower turns. Sagittal displacement of Reissner's membrane was projected to be most pronounced in the apical turn in all the stages of early cochlea hydrops.
Conclusion: Structural features appear to underlie a differential susceptibility to hydrops in the human cochlea. The flattened spiral shape of the human cochlea coupled with the anticlastic configuration and the distensile characteristics of Reissner's membrane are projected to result in distinct histological stages as hydropic disease in the cochlea progresses.
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http://dx.doi.org/10.1002/lio2.70041 | DOI Listing |
Laryngoscope Investig Otolaryngol
December 2024
Department of Otolaryngology Columbia University New York New York USA.
J Biomed Phys Eng
October 2024
Faculty of Engineering Science, Kansai University, Osaka, Japan.
Multiple propagation modes progress along the basilar membrane and Reissner's membrane, called basilar membrane mode (BM mode) and Reissner's membrane mode (RM mode), respectively. This study focuses on the effects of the RM mode on the hearing process and investigates the difference in the attenuation characteristics between the RM and BM modes in the vicinity of the cochlea base by using modal analysis. Results indicated that the RM mode has fewer effects on the hearing process, except otoacoustic emissions, due to its bigger attenuation constant than the BM mode in the vicinity of the cochlea base.
View Article and Find Full Text PDFbioRxiv
September 2024
Department of Psychology and Neuroscience, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina, United States.
Rodent drug self-administration leads to compromised ability of astrocytes to maintain glutamate homeostasis within the brain's reward circuitry, as well as reductions in surface area, volume, and synaptic colocalization of astrocyte membranes. However, the mechanisms driving astrocyte responses to cocaine are unknown. Here, we report that long-access cocaine self-administration followed by prolonged home cage abstinence results in decreased branching complexity of nucleus accumbens astrocytes, characterized by the loss of peripheral processes.
View Article and Find Full Text PDFCureus
August 2024
Department of Anatomy, All India Institute of Medical Sciences, Bibinagar, Hyderabad, IND.
The search for potential lymphatic routes through the cochlea, or membranous portions of the inner ear labyrinth, remains a significant challenge. Researchers often focus on lower mammals rather than humans to uncover these pathways. This review aims to delineate the speculated lymphatic routes within the inner ear to date.
View Article and Find Full Text PDFMil Med
August 2024
School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK 73019, USA.
Introduction: Auditory disabilities like tinnitus and hearing loss caused by exposure to blast overpressures are prevalent among military service members and veterans. The high-pressure fluctuations of blast waves induce hearing loss by injuring the tympanic membrane, ossicular chain, or sensory hair cells in the cochlea. The basilar membrane (BM) and organ of Corti (OC) behavior inside the cochlea during blast remain understudied.
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