Subramaniam M, Henderson D, Spongr V
Department of Communicative Disorders and Sciences, State University of New York, Buffalo.
Ear Hear. 1994 Aug;15(4):299-309. doi: 10.1097/00003446-199408000-00004.
Distortion-product otoacoustic emissions (DPOAEs) are gaining popularity as indicators of the status of the cochlea. The efficacy of DPOAEs as indicators of changes in thresholds and the status of outer hair cells (OHCs) were examined using an animal model. Monaural chinchillas were exposed to an octave band noise (OBN) centered at 0.5 kHz at 95 dB SPL for 6 hr/day for 10 days. DPOAEs and evoked potential thresholds were recorded before, during, and after the exposures. The animals were sacrificed 5 days after the last exposure, and the status of OHCs was assessed using scanning electron microscopy. Results indicate that both evoked potential thresholds and DPOAEs effectively track the temporary changes associated with interrupted noise exposures. However, DPOAEs often recovered to their baseline even when there was a threshold shift of > 25 dB. Furthermore, at 5 days postexposure, both evoked potential thresholds and DPOAEs were normal despite considerable OHC pathology. The findings suggest that normal DPOAEs may not guarantee normal cochlear status and, therefore, results of DPOAE measurements should be interpreted cautiously.
畸变产物耳声发射（DPOAEs）作为耳蜗状态的指标正越来越受到关注。本研究使用动物模型，考察了DPOAEs作为阈值变化和外毛细胞（OHCs）状态指标的有效性。将单耳的毛丝鼠暴露于中心频率为0.5 kHz、声压级为95 dB SPL的倍频程带噪声（OBN）中，每天暴露6小时，持续10天。在暴露前、暴露期间和暴露后记录DPOAEs和诱发电位阈值。在最后一次暴露后5天处死动物，使用扫描电子显微镜评估OHCs的状态。结果表明，诱发电位阈值和DPOAEs均能有效追踪与间歇性噪声暴露相关的暂时性变化。然而，即使阈值偏移>25 dB，DPOAEs通常仍能恢复到基线水平。此外，暴露后5天时，尽管OHCs存在相当程度的病变，但诱发电位阈值和DPOAEs均正常。这些发现表明，DPOAEs正常并不一定保证耳蜗状态正常，因此，对DPOAE测量结果的解释应谨慎。
