Fetterman B L
Shea Ear Clinic, Memphis, Tennessee, USA.
Laryngoscope. 2001 Jun;111(6):946-54. doi: 10.1097/00005537-200106000-00004.
Because endolymphatic hydrops causes cochlear malfunction, and both otoacoustic emissions and cochlear microphonics measure specific cochlear activities, some insight into the pathology of Meniere's disease might be gained by using these two test modalities. Specifically, the involvement of cochlear outer hair cells in patients with endolymphatic hydrops may be detected. Furthermore, it is hoped that these two tests might help determine which regions of the cochlea are affected by endolymphatic hydrops, as well as where along the auditory pathway abnormalities are present.
Data were gathered prospectively on patients presenting to a private, tertiary referral otology/neurotology practice.
From February 1999 to April 2000, clinical information was collected on patients presenting with vertigo, hearing loss (HL), sudden HL, fluctuant HL, aural fullness, and/or tinnitus. Data included demographics, diagnosis, pure-tone and speech audiometry, tympanometry, summating potential, action potential, cochlear microphonic, and distortion-product otoacoustic emissions. Descriptive statistics were calculated, and relationships between distortion-product otoacoustic emissions and cochlear microphonics in patients with hydrops (defined as summating potential to action potential ratio > or =0.40) and without hydrops were analyzed.
Distortion-product otoacoustic emissions were present more often and had larger amplitudes at the lower frequencies. No differences were found in the presence of distortion-product otoacoustic emissions across the frequencies for the two groups, but larger mean amplitudes were found for hydropic ears at 7966 Hz. As hearing levels worsened, both hydropic and nonhydropic ears were less likely to have emissions present; however, 18% of hydropic ears had emissions unexpectedly present when the pure-tone thresholds were > or =50 dB. The cochlear microphonic from the hydrops group tended to be smaller, but this was not statistically significant. Analysis of variance showed a small negative correlation between summating potential to action potential ratio and level of emission at 1968 Hz in hydropic ears; otherwise, there was no relationship between the ratio and emissions. The only statistically significant finding when analyzing the relationship between cochlear microphonic and otoacoustic emission was a small positive correlation between level of microphonic and level of emission at 1406 Hz in hydropic ears. No significant relationships were found between hearing thresholds and emissions or microphonics.
Even though both distortion-product otoacoustic emissions (DPOAEs) and cochlear microphonics (CMs) measure specific cochlear activities, they were not found to be useful for differentiating patients with hydrops from those without. In some patients, however, unexpected distortion-product otoacoustic emissions were present. This may represent localizing information about which regions of the cochlea are being affected by hydrops in these patients. Also, a small positive correlation between the CM and the DPOAE at 1406 Hz was detected in the hydrops group, which may represent the effects of endolymphatic hydrops on the outer hair cell. Future investigations involving hydropic patients with unexpected DPOAEs and studies looking for more DPOAE and CM correlations at frequencies surrounding 1406 Hz are being planned.
由于内淋巴积水会导致耳蜗功能障碍，而耳声发射和耳蜗微音电位均能测量特定的耳蜗活动，因此使用这两种检测方式可能有助于深入了解梅尼埃病的病理情况。具体而言，或许可以检测出内淋巴积水患者耳蜗外毛细胞的受累情况。此外，期望这两种检测能够帮助确定耳蜗的哪些区域受到内淋巴积水的影响，以及听觉通路中哪些部位存在异常。
前瞻性收集前往一家私立三级转诊耳科/神经耳科诊所就诊患者的数据。
1999年2月至2000年4月，收集了患有眩晕、听力损失（HL）、突发性HL、波动性HL、耳胀满感和/或耳鸣患者的临床信息。数据包括人口统计学资料、诊断、纯音及言语听力测定、鼓室图、总和电位、动作电位、耳蜗微音电位以及畸变产物耳声发射。计算描述性统计量，并分析积水患者（定义为总和电位与动作电位比值≥0.40）和无积水患者畸变产物耳声发射与耳蜗微音电位之间的关系。
畸变产物耳声发射在低频时更常出现且幅度更大。两组在各频率上畸变产物耳声发射的出现情况无差异，但积水耳在7966Hz时平均幅度更大。随着听力水平变差，积水耳和非积水耳出现耳声发射的可能性均降低；然而，当纯音阈值≥50dB时，18%的积水耳意外出现耳声发射。积水组的耳蜗微音电位往往较小，但无统计学意义。方差分析显示，积水耳中总和电位与动作电位比值与1968Hz时耳声发射水平呈小的负相关；否则，该比值与耳声发射之间无关联。分析耳蜗微音电位与耳声发射关系时，唯一具有统计学意义的发现是积水耳中1406Hz时微音电位水平与耳声发射水平呈小的正相关。听力阈值与耳声发射或微音电位之间未发现显著关联。
尽管畸变产物耳声发射（DPOAE）和耳蜗微音电位（CM）均能测量特定的耳蜗活动，但它们并未被发现有助于区分积水患者与非积水患者。然而，在一些患者中意外出现了畸变产物耳声发射。这可能代表了关于这些患者耳蜗哪些区域受积水影响的定位信息。此外，在积水组中检测到1406Hz时CM与DPOAE之间存在小的正相关，这可能代表内淋巴积水对外毛细胞的影响。正在计划对有意外DPOAE的积水患者进行进一步研究，以及寻找1406Hz周围频率更多DPOAE与CM相关性的研究。
