Lütkenhöner Bernd, Basel Türker
ENT Clinic, Münster University Hospital, Münster, Germany.
BMC Ear Nose Throat Disord. 2014 Nov 24;14:12. doi: 10.1186/1472-6815-14-12. eCollection 2014.
Recent advances in magnetic resonance imaging make it possible to visualize the presumed pathophysiologic correlate of Menière's disease: endolymphatic hydrops. As traditional diagnostic tests can provide only indirect evidence, they are hardly competitive in this respect and need to be rethought. This is done here for the glycerol test.
The data of a previous retrospective analysis of the glycerol test in patients with suspected Menière's disease are reinterpreted using a simple model. The mean threshold reduction (MTR) in the frequency range from 125 to 1500 Hz (calculated from audiograms obtained immediately before and four hours after the glycerol intake) is used as the test statistic. The proposed model explains the frequency distribution of the observed MTR by the convolution of a Gaussian probability density function (representing measurement errors) with a template representing the frequency distribution of the true MTR. The latter is defined in terms of two adjustable parameters. After fitting the model to the data, the performance of the test is evaluated using receiver operating characteristic (ROC) analysis.
The cumulative frequency distribution of the observed MTR can be explained almost perfectly by the model. According to the ROC analysis performed, the capability of the currently used audiometric procedure to detect a glycerol-induced threshold reduction corresponds to a diagnostic test of rather high accuracy (area under the ROC curve greater than 0.9). Simulations show that methodological improvements could further enhance the performance.
Owing to their ability to reveal functional aspects without an obvious morphological correlate, traditional test for Menière's disease could be decisive for defining the stage of the disease. A distinctive feature of the glycerol test is that it is capable of determining, with high accuracy, whether the pathophysiologic condition of the inner ear is partially reversible. Prospectively, this could help to estimate the chances of specific therapies.
磁共振成像的最新进展使得可视化梅尼埃病假定的病理生理关联——内淋巴积水成为可能。由于传统诊断测试只能提供间接证据，在这方面它们几乎没有竞争力，需要重新思考。本文针对甘油试验进行了此项工作。
使用一个简单模型重新解释先前对疑似梅尼埃病患者甘油试验的回顾性分析数据。将125至1500赫兹频率范围内的平均阈值降低（MTR）（根据摄入甘油前及摄入后4小时获得的听力图计算）用作检验统计量。所提出的模型通过将高斯概率密度函数（代表测量误差）与代表真实MTR频率分布的模板进行卷积来解释观察到的MTR的频率分布。后者由两个可调参数定义。在将模型拟合到数据后，使用受试者工作特征（ROC）分析评估该测试的性能。
观察到的MTR的累积频率分布几乎可以由该模型完美解释。根据所进行的ROC分析，当前使用的听力测定程序检测甘油诱导的阈值降低的能力相当于一项具有相当高准确性的诊断测试（ROC曲线下面积大于0.9）。模拟表明，方法学上的改进可以进一步提高性能。
由于传统的梅尼埃病测试能够揭示功能方面而无明显的形态学关联，因此对于确定疾病阶段可能具有决定性作用。甘油试验的一个显著特点是它能够高精度地确定内耳的病理生理状况是否部分可逆。前瞻性地看，这有助于评估特定治疗的可能性。
