Davis Bob, Qiu Wei, Hamernik Roger P
Auditory Research Laboratory, Plattsburgh State University of New York, 107 Beaumont Hall, 101 Broad St., Plattsburgh, NY, 12901, USA.
Hear Res. 2004 Jan;187(1-2):12-24. doi: 10.1016/s0378-5955(03)00339-3.
Distortion product otoacoustic emissions (DPOAE), permanent threshold shifts (PTS) and outer hair cell (OHC) losses were analyzed in a population of 187 noise-exposed chinchillas to determine the predictive accuracy (sensitivity and specificity) of the DPOAE for PTS and OHC loss. Auditory evoked potentials (AEP) recorded from the inferior colliculus of the brainstem were used to estimate hearing thresholds and surface preparation histology was used to determine sensory cell loss. The overlapping cumulative distributions and high variability in emission responses for both PTS and OHC loss made it difficult to predict AEP threshold and OHC loss from DPOAE level measurements alone. Using a strict criterion (i.e. emissions better than the 5th percentile of the preexposure DPOAE level, and PTS< or = 5 dB or OHC loss< or = 5%), it was found that the postexposure DPOAE level could be used with reasonable confidence to determine if the status of peripheral auditory system was either normal (i.e. PTS< or = 5 dB) or abnormal (PTS>30 dB or OHC loss>40%). However, the high variability of individual DPOAE responses resulted in a broad region of 'uncertainty' (i.e. 5<PTS< or = 30 dB and 5%<OHC loss< or = 40%) making it difficult in the chinchilla model to use the postexposure DPOAE level with confidence to predict in individual subjects the amount of PTS or OHC loss. Our results also indicate that significant reductions in the amplitude of the DPOAE are related primarily to a systematic loss of OHCs, and that a postexposure DPOAE level< or = 10 dB SPL, obtained with a low frequency primary level of 65 dB SPL, represents a criterion value which can serve as an indication of significant OHC loss (> or = 50%) or PTS (> or = 35 dB) in noise-exposed chinchillas. Based on an exponential regression analysis of individual subjects, correlations were higher for PTS/DPOAE than for OHC loss/DPOAE.
在187只暴露于噪声的毛丝鼠群体中，分析了畸变产物耳声发射（DPOAE）、永久性阈移（PTS）和外毛细胞（OHC）损失，以确定DPOAE对PTS和OHC损失的预测准确性（敏感性和特异性）。从脑干下丘记录的听觉诱发电位（AEP）用于估计听力阈值，表面制备组织学用于确定感觉细胞损失。PTS和OHC损失的发射反应重叠的累积分布和高变异性使得仅根据DPOAE水平测量来预测AEP阈值和OHC损失变得困难。使用严格的标准（即发射优于暴露前DPOAE水平的第5百分位数，且PTS≤5 dB或OHC损失≤5%），发现暴露后DPOAE水平可用于合理确定外周听觉系统的状态是正常（即PTS≤5 dB）还是异常（PTS>30 dB或OHC损失>40%）。然而，个体DPOAE反应的高变异性导致了一个广泛的“不确定”区域（即5<PTS≤30 dB且5%<OHC损失≤40%），这使得在毛丝鼠模型中难以自信地使用暴露后DPOAE水平来预测个体受试者的PTS或OHC损失量。我们的结果还表明，DPOAE幅度的显著降低主要与OHC的系统性损失有关，并且在低频初级水平为65 dB SPL时获得的暴露后DPOAE水平≤10 dB SPL代表一个标准值，可作为暴露于噪声的毛丝鼠中显著OHC损失（≥50%）或PTS（≥35 dB）的指标。基于对个体受试者的指数回归分析，PTS/DPOAE的相关性高于OHC损失/DPOAE的相关性。
