John Curtin School of Medical Research, The Australian National University, Canberra, ACT 2601, Australia.
Institute of Physiology and Pathology of Hearing, ul. Mochnackiego 10, 02-042 Warsaw, Poland.
Medicina (Kaunas). 2023 Jun 22;59(7):1187. doi: 10.3390/medicina59071187.
: This narrative review of the literature explores the effect of body temperature on hearing. In particular, its focus is on extended high frequency (EHF) hearing-the range beyond the standard audiometric limit of 8 kHz. Such high frequencies are the first to be affected by noise-induced hearing loss, and so monitoring them can provide an early warning sign of incipient damage. : This review builds on a personal literature database of 216 references covering the general topic of EHF hearing; the procedure was to then identify papers related to whole-body or cochlear cooling. A starting point was the paper by Munjal et al. who in 2013 reported changes of up to 15-30 dB in the EHF thresholds of subjects who had undergone cardiopulmonary bypass (CBP) surgery, which typically involves mild to moderate hypothermia-cooling of the blood-to reduce cellular oxygen demand and minimise tissue damage. : Reviewing the surrounding literature, we find that although CBP surgery by itself can impair hearing thresholds, lower body and cochlear temperatures in general provide neuroprotective effects. A connection between hearing loss and CBP surgery has been periodically documented, but the mechanism behind it has yet to be conclusively identified. : The observations reviewed here tend to confirm the otoprotective effects of cooling. We consider that the high sensitivity of EHF thresholds to temperature is a major factor that has not been sufficiently recognised, although it has important implications for otological research and practice. Two important inferences are that, first, monitoring EHF thresholds might have considerable value in audiology, and, second, that lowering temperature of the cochlea during cochlear implantation might provide substantially better hearing preservation, as some researchers have already suggested.
这篇文献综述探讨了体温对听力的影响。特别是，它关注的是扩展高频（EHF）听力——超出标准听力极限 8 kHz 的范围。如此高的频率是最早受到噪声性听力损失影响的频率，因此监测它们可以提供早期损伤的预警信号。
这篇综述建立在我个人的 216 篇涵盖 EHF 听力一般主题的文献数据库之上；然后，识别与全身或耳蜗冷却相关的论文。起点是 Munjal 等人在 2013 年发表的论文，他们报告说，接受心肺旁路（CBP）手术的受试者的 EHF 阈值发生了高达 15-30 dB 的变化，CBP 手术通常涉及轻度至中度低温——冷却血液以降低细胞氧需求并最大程度地减少组织损伤。
回顾周围的文献，我们发现尽管 CBP 手术本身可能会损害听力阈值，但一般来说，较低的体温和耳蜗温度提供神经保护作用。听力损失与 CBP 手术之间的联系已被定期记录，但背后的机制尚未得到明确确定。
这里综述的观察结果倾向于证实冷却的听力保护作用。我们认为，EHF 阈值对温度的高度敏感性是一个尚未得到充分认识的主要因素，尽管它对耳科学研究和实践具有重要意义。两个重要的推论是，首先，监测 EHF 阈值在听力学中可能具有相当大的价值，其次，耳蜗植入期间降低耳蜗温度可能会提供更好的听力保护，正如一些研究人员已经提出的那样。
