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Imaging the Aging Cochlea with Light-Sheet Fluorescence Microscopy
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Conductive Hearing Loss with Age-A Histologic and Audiometric Evaluation
Ivo Dobrev1, Daniel Dillinger1, Letizia Meier1
1Department of Otorhinolaryngology, Head & Neck Surgery, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland.
Journal of Clinical Medicine
|June 2, 2021
Summary
Age-related changes in the incudo-malleolar joint (IMJ) and incudo-stapedial joint (ISJ) show wider joint spaces and decreased cartilage thickness. These changes correlate with age-related shifts in air-bone gap (ABG) at different frequencies.
Area of Science:
- Otolaryngology
- Anatomy
- Audiology
Background:
- The middle ear ossicles, including the malleus, incus, and stapes, are crucial for hearing transmission.
- Age-related changes in the joints connecting these ossicles may influence auditory function.
Purpose of the Study:
- To quantify age-related structural changes in the incudo-malleolar joint (IMJ) and incudo-stapedial joint (ISJ).
- To analyze the correlation between these joint changes and age-related alterations in the air-bone gap (ABG).
Main Methods:
- Retrospective histological analysis of 153 IMJs and 106 ISJs from subjects aged 0-70 years.
- Retrospective audiometric analysis of 1760 ears from 974 subjects aged 20-80 years to assess ABG.
- Correlation of histological parameters and ABG with subject age.
Main Results:
- Joint spaces significantly widened with age (IMJ: 44 µm to 100 µm; ISJ: 28 µm to 69 µm).
- Incus cartilage thickness decreased in the first 20 years (IMJ: 88 µm to 65 µm; ISJ: 44 µm to 35 µm).
- ABG was larger at 500 Hz and smaller at 4000 Hz in older adults (60-80 years) compared to younger adults (20-40 years).
Conclusions:
- Increased joint spaces may reduce middle ear stiffness, potentially explaining observed ABG shifts with age.
- While average changes are clinically minor, significant ABG variations occur in some individuals.
- Age-related anatomical changes in the IMJ and ISJ are linked to alterations in hearing thresholds.
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