Quantitative evaluation of myelinated nerve fibres and hair cells in cochleae of humans with age-related high-tone hearing loss
Quantitative evaluation of myelinated nerve fibres and hair cells in cochleae of humans with age-related high-tone hearing loss
复制标题
DOI：
10.1016/0378-5955(95)00158-1
复制
发表时间：
1995-11-01
期刊：
影响因子：
2.8
通讯作者：
SchrottFischer, A
中科院分区：
文献类型：
--
作者：
Felder, E;SchrottFischer, A
在这项研究中，来自8个个体的9个人颞骨在死后1-3小时内通过外淋巴灌注用Karnovsky溶液固定，并使用“块表面法”（Spoendlin和Brun，1974; Spoendlin和Schrott，1987）和“显微解剖法”（Johnsson和Hawkins，1967）进行检查。7人的听力图显示为典型的感觉神经性老年性聋的高频听力损失。对骨螺旋板中的内毛细胞（MHC）和外毛细胞（OHC）以及有髓神经纤维进行计数，以将听力曲线与毛细胞和神经纤维密度相关联。“块-表面”法可以精确地计数毛细胞和有髓神经纤维，同时最大限度地保留耳蜗结构。耳蜗最显著的变化不是预期的毛细胞损失，而是沿着沿着整个耳蜗长度的螺旋板中的神经纤维明显损失。这种神经纤维的损失被发现与年龄有关。与听力正常的中年人相比，60岁以上的人耳蜗中的听力下降高达30-40%。在2例病例中，只有13%的纤维保留在耳蜗的某些区域。毛细胞计数显示减少约80%的OHCs，主要是在耳蜗的顶端部分，和只有很少的差异，与一组听力正常的中年人相比，IHC的数量，我们得出结论，既不损失的毛细胞，也不主要退化的神经纤维单独可以完全解释高音损失。毛细胞或神经元在细胞水平上的损伤可能会导致阈值升高。
In this study 9 human temporal bones from 8 individuals were fixed with Karnovsky solution by perilymphatic perfusion within 1-3 h after death and examined using the 'block-surface method' (Spoendlin and Brun, 1974; Spoendlin and Schrott, 1987) and the 'micro-dissection method' (Johnsson and Hawkins, 1967). The audiogram of 7 individuals showed high-tone hearing loss, typical for sensory-neural presbycusis. The inner (IHC) and outer hair cells (OHC) and the myelinated nerve fibers in the osseous spiral lamina were counted to correlate audiometric curves with hair-cell and nerve-fiber densities. The 'block-surface' method allows accurate hair-cell and myelinated nerve-fiber enumeration with maximal preservation of cochlear structures.The most significant change in the cochlea was not the expected loss of hair cells but an evident loss of nerve fibres in the spiral lamina along the entire length of the cochlea. This loss of nerve fibres was found to be age-related. Reductions up to 30-40% in comparison to normal-hearing middle-aged persons were found in cochleae from persons older than 60 years. In 2 cases only 13% of the fibres remained in some regions of the cochlea. The hair-cell counts showed a reduction of approximately 80% of the OHCs, mainly in the apical parts of the cochlea, and only little differences in the number of IHCs as compared with a group of normal-hearing middle-aged persons.We conclude that neither loss of hair cells nor primary degeneration of nerve fibres alone can fully explain the high-tone loss. Probably injuries of hair cells or neuronal elements at the cellular level can cause threshold elevation.