Weak Middle-Ear-Muscle Reflex in Humans with Noise-Induced Tinnitus and Normal Hearing May Reflect Cochlear Synaptopathy.
Weak Middle-Ear-Muscle Reflex in Humans with Noise-Induced Tinnitus and Normal Hearing May Reflect Cochlear Synaptopathy.
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DOI：
10.1523/eneuro.0363-17.2017
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发表时间：
2017-11
期刊：
影响因子：
3.4
通讯作者：
Oxenham AJ
中科院分区：
文献类型：
--
作者：
Wojtczak M;Beim JA;Oxenham AJ
慢性耳鸣是一种常见的听力障碍，但目前还没有成功的治疗方法或客观的诊断测试。本研究的目的是调查耳鸣的存在和中耳肌反射（MEMR）的强度之间的关系，在人类正常和接近正常的听力。咔哒声被用作测试刺激，以获得反射激活对耳道声压的影响的宽带测量。该反射是使用对侧宽带噪声引起的。结果表明，与无耳鸣对照组相比，噪声引起的连续性耳鸣和正常或接近正常的听力阈值的个体的反射强度显着降低。由于耳鸣组的反射强度增长较浅，两组之间的差异随着激发物水平的增加而增加。耳鸣对中耳肌反射强度的影响在男性和女性之间没有显着差异。较弱的反射不能解释耳鸣和对照组之间的听力阈值差异。我们在人类中的发现与噪声暴露动物中中耳肌肉反射减少的发现之间的相似性表明，临床听力正常的个体中噪声引起的耳鸣可能是耳蜗突触病的结果，耳蜗内毛细胞（IHC）和耳蜗神经（AN）纤维之间的突触连接丧失，被称为隐性听力损失。
Chronic tinnitus is a prevalent hearing disorder, and yet no successful treatments or objective diagnostic tests are currently available. The aim of this study was to investigate the relationship between the presence of tinnitus and the strength of the middle-ear-muscle reflex (MEMR) in humans with normal and near-normal hearing. Clicks were used as test stimuli to obtain a wideband measure of the effect of reflex activation on ear-canal sound pressure. The reflex was elicited using a contralateral broadband noise. The results show that the reflex strength is significantly reduced in individuals with noise-induced continuous tinnitus and normal or near-normal audiometric thresholds compared with no-tinnitus controls. Due to a shallower growth of the reflex strength in the tinnitus group, the difference between the two groups increased with increasing elicitor level. No significant difference in the effect of tinnitus on the strength of the middle-ear muscle reflex was found between males and females. The weaker reflex could not be accounted for by differences in audiometric hearing thresholds between the tinnitus and control groups. Similarity between our findings in humans and the findings of a reduced middle-ear muscle reflex in noise-exposed animals suggests that noise-induced tinnitus in individuals with clinically normal hearing may be a consequence of cochlear synaptopathy, a loss of synaptic connections between inner hair cells (IHCs) in the cochlea and auditory-nerve (AN) fibers that has been termed hidden hearing loss.