Department of Otolaryngology-Head and Neck Surgery, University of Toronto, Toronto, Ontario, Canada.
Laryngoscope. 2011 Jan;121(1):202-13. doi: 10.1002/lary.21078.
OBJECTIVES/HYPOTHESIS: Otoacoustic emissions (OAE) can be suppressed with activation of the medial olivocochlear neural pathway by stimulation of the contralateral ear. The primary objective of this study was to assess the feasibility of using olivocochlear mediated OAE suppression to test neonatal hearing with a novel device that detects changes in distortion product (DP)OAE level with high temporal resolution. The secondary objective was to investigate whether temporal parameters of the response can be determined with this technique and used in the assessment of neonates at risk of auditory neuropathy spectrum disorder (ANSD).
Prospective translational study of novel hearing assessment technique.
There were 46 neonates tested in a clinic or neonatal intensive care unit (NICU). DPOAE were recorded in real time with narrow band pass digital filtering (1 ms temporal resolution) during presentation of an intermittent contralateral broadband noise stimulus. Magnitude and latency of the contralateral suppression response were compared with hearing outcome (auditory brainstem response screen and clinical follow-up) and risk factors for hearing loss, particularly hyperbilirubinemia as a risk factor for ANSD.
: Contralateral suppression was identified in all of 38 neonates with detectable DPOAE and normal hearing, most reliably at f(2) = 4.4 kHz (average values = 1 dB suppression from DP level of 14 dB SPL using 0.55 s contralateral stimulus at 50 dB SPL). Sensorineural hearing loss was identified in three cases (6.5%) and ANSD in five cases (11% of all neonates tested). Contralateral suppression was absent in two of the ANSD cases (one associated with cochlear nerve aplasia, the other with hyperbilirubinemia) and present in three. The median latency for onset of contralateral suppression was 60 ms and offset latency 83 ms. The latency for offset of suppression was longer in neonates who required treatment for hyperbilirubinemia at 123 ms (P = .02, Mann-Whitney rank sum test). Latency measurements were determined with high intraobserver reliability (Pearson product moment correlation coefficient > 0.96).
Contralateral suppression of real-time DPOAE can reliably be identified in neonates. This is likely a manifestation of olivocochlear activity, although middle ear muscle reflexes might contribute to suppression in some circumstances. The technique provides a feasible objective test of hearing in neonates that can be applied in the NICU setting without sedation. The presence of a response indicates detection of sound by the contralateral ear and effective brainstem transmission of neural signals, therefore providing a more sensitive test of hearing than OAE alone. The high temporal resolution of the technique allows measurement of latency of the response. These benefits help to identify neonates at risk of ANSD and have the potential to provide prognostic information that will assist in the management of this unpredictable disorder. Further development of the technique is indicated with regard to determination of hearing threshold, frequency specific testing, and automation of response detection.
目的/假设：耳声发射（OAE）可以通过刺激对侧耳朵来抑制内侧橄榄耳蜗神经通路的激活。本研究的主要目的是评估使用橄榄耳蜗介导的 OAE 抑制来测试新生儿听力的可行性，该技术使用新设备以高时间分辨率检测失真产物（DP）OAE 水平的变化。次要目的是研究是否可以使用这种技术确定响应的时间参数，并用于评估有听觉神经病谱系障碍（ANSD）风险的新生儿。
新型听力评估技术的前瞻性转化研究。
在诊所或新生儿重症监护病房（NICU）中对 46 名新生儿进行了测试。在呈现间歇性对侧宽带噪声刺激时，使用窄带通数字滤波（1ms 时间分辨率）实时记录 DPOAE。将对侧抑制反应的幅度和潜伏期与听力结果（听觉脑干反应筛查和临床随访）以及听力损失的危险因素（特别是胆红素升高作为 ANSD 的危险因素）进行比较。
在所有 38 名具有可检测 DPOAE 和正常听力的新生儿中均识别出对侧抑制，在 f（2）=4.4kHz 时最可靠（使用 0.55s 对侧刺激，50dBSPL 时 DP 水平为 14dBSPL，平均抑制值为 1dB）。在 3 例（6.5%）中发现感音神经性听力损失，在 5 例（所有接受测试的新生儿的 11%）中发现 ANSD。在 2 例 ANSD 病例中（1 例与耳蜗神经发育不全有关，另 1 例与高胆红素血症有关）不存在对侧抑制，在 3 例中存在对侧抑制。对侧抑制开始的潜伏期中位数为 60ms，抑制结束的潜伏期为 83ms。需要治疗高胆红素血症的新生儿的抑制结束潜伏期较长，为 123ms（P=0.02，曼-惠特尼秩和检验）。潜伏期测量具有很高的观察者内可靠性（皮尔逊积矩相关系数>0.96）。
在新生儿中可靠地识别实时 DPOAE 的对侧抑制。这可能是橄榄耳蜗活动的表现，尽管在某些情况下中耳肌反射可能会对抑制产生贡献。该技术提供了一种可行的新生儿听力客观测试方法，可在无镇静的情况下在 NICU 环境中应用。反应的存在表明对侧耳朵检测到声音，并且神经信号在脑干中有效传输，因此比单独的 OAE 提供更敏感的听力测试。该技术的高时间分辨率允许测量响应的潜伏期。这些优点有助于识别有 ANSD 风险的新生儿，并有可能提供有助于管理这种不可预测疾病的预后信息。需要进一步开发该技术，以确定听力阈值、频率特异性测试和反应检测的自动化。
