Kujawa Sharon G, Liberman M Charles
Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts 02115, USA.
J Neurosci. 2009 Nov 11;29(45):14077-85. doi: 10.1523/JNEUROSCI.2845-09.2009.
Overexposure to intense sound can cause temporary or permanent hearing loss. Postexposure recovery of threshold sensitivity has been assumed to indicate reversal of damage to delicate mechano-sensory and neural structures of the inner ear and no persistent or delayed consequences for auditory function. Here, we show, using cochlear functional assays and confocal imaging of the inner ear in mouse, that acoustic overexposures causing moderate, but completely reversible, threshold elevation leave cochlear sensory cells intact, but cause acute loss of afferent nerve terminals and delayed degeneration of the cochlear nerve. Results suggest that noise-induced damage to the ear has progressive consequences that are considerably more widespread than are revealed by conventional threshold testing. This primary neurodegeneration should add to difficulties hearing in noisy environments, and could contribute to tinnitus, hyperacusis, and other perceptual anomalies commonly associated with inner ear damage.
过度暴露于高强度声音会导致暂时性或永久性听力损失。暴露后阈值敏感性的恢复被认为表明内耳精细的机械感觉和神经结构的损伤得到了逆转，并且对听觉功能没有持续或延迟的影响。在这里，我们使用小鼠内耳的耳蜗功能测定和共聚焦成像表明，导致适度但完全可逆的阈值升高的声学过度暴露使耳蜗感觉细胞保持完整，但会导致传入神经末梢急性丧失和耳蜗神经延迟变性。结果表明，噪声引起的耳部损伤具有渐进性后果，其范围比传统阈值测试所揭示的要广泛得多。这种原发性神经变性会增加在嘈杂环境中听力的困难，并可能导致耳鸣、听觉过敏以及其他通常与内耳损伤相关的感知异常。
