Konrádsson K S, Carlborg B, Grenner J, Tjernström O
Department of Otolaryngology-Head and Neck Surgery, University Hospital, Lund, Sweden.
Laryngoscope. 1999 Jan;109(1):59-64. doi: 10.1097/00005537-199901000-00013.
To elucidate the effects of hypobaric pressure on cochlear hydrodynamics in patents with well-defined Meniere's disease.
Sixteen patients were consecutively selected. Elevated hearing threshold levels and pathological transtympanal electrocochleography (tt-ECOG) were confirmed at the day of trial. The patients were exposed to repeated episodes of hypobaric pressure in a pressure chamber. The rate (20 daPa/s) and magnitude (-285 daPa) of chamber pressure change were low. The induced tympanic overpressure (+185 daPa) was continuously monitored and any tympanic equilibration was avoided.
The results of Bekesy and speech audiometry as well as tt-ECOG performed immediately before and after exposure were compared. The importance of chamber pressure change, number of hypobaric episodes, duration of exposure, and the induced relative tympanic overpressure was tested.
It is shown that the relative tympanic overpressure is the most important factor to affect the cochlear hydrodynamics. Higher relative overpressure was associated with improvement of hearing threshold levels, while the ECOG results tended to improve with lower induced tympanic overpressure.
The importance of tympanic overpressure shown in this study is in agreement with previous findings from hypobaric animal experiments. The inverse relation of psychoacoustic and ECOG tests suggests that the two methods evaluate different parameters, perhaps contributing differently to the physiology of hearing.
阐明低压对明确诊断为梅尼埃病患者耳蜗流体动力学的影响。
连续选取16例患者。在试验当天确认听力阈值升高及病理性经鼓膜电耳蜗图（tt-ECOG）异常。患者在压力舱中反复暴露于低压环境。舱内压力变化速率（20 daPa/s）和幅度（-285 daPa）较低。持续监测诱发的鼓膜超压（+185 daPa），避免鼓膜平衡。
比较暴露前后立即进行的贝凯西听力计测试和言语听力测试结果以及tt-ECOG结果。测试舱内压力变化、低压暴露次数、暴露持续时间和诱发的相对鼓膜超压的重要性。
结果表明，相对鼓膜超压是影响耳蜗流体动力学的最重要因素。较高的相对超压与听力阈值水平的改善相关，而ECOG结果在较低的诱发鼓膜超压时趋于改善。
本研究显示的鼓膜超压的重要性与先前低压动物实验的结果一致。心理声学测试和ECOG测试的反向关系表明，这两种方法评估的是不同参数，可能对听力生理学的贡献也不同。
