Maurer J, Hinni M, Beck A, Mann W
Ear, Nose, and Throat Department, University of Mainz Medical School, Germany.
Otolaryngol Head Neck Surg. 1995 Mar;112(3):369-74. doi: 10.1016/S0194-59989570269-5.
Transitory evoked otoacoustic emissions are normal phenomena observed in most persons with hearing levels greater than 35 dB. Further, masking of the contralateral ear produces amplitude reductions in the transitory evoked otoacoustic emissions. We have undertaken a study of transitory evoked otoacoustic emissions in 20 patients with acoustic neuroma. All patients were assessed for transitory evoked otoacoustic emissions bilaterally, with and without contralateral masking with white band noise at 40, 50, and 60 dB. We found that transitory evoked otoacoustic emissions were present in 30% of ears with tumor and that the presence of transitory evoked otoacoustic emissions is associated with improved preoperative hearing levels, but that tumor size is not associated with the presence or absence of transitory evoked otoacoustic emissions. The amplitude of transitory evoked otoacoustic emissions from ears with tumor, when present, is decreased when compared with normal ears of normal patients. Further, with contralateral masking little of the amplitude reduction observed in normal patients is observed in the ears with acoustic neuroma. However, with masking of the contralateral ear, the ear without tumor demonstrated significantly greater amplitude reductions than normal ears from normal patients (p = 0.0006). Pertinent anatomy and possible explanations for these findings are discussed.
瞬态诱发耳声发射是在大多数听力水平大于35分贝的人身上观察到的正常现象。此外，对侧耳的掩蔽会使瞬态诱发耳声发射的幅度降低。我们对20例听神经瘤患者的瞬态诱发耳声发射进行了研究。所有患者均接受双侧瞬态诱发耳声发射评估，分别在有和没有用40、50和60分贝的白噪声对侧耳进行掩蔽的情况下进行。我们发现，30%有肿瘤的耳朵存在瞬态诱发耳声发射，且瞬态诱发耳声发射的存在与术前听力水平的改善有关，但肿瘤大小与瞬态诱发耳声发射的有无无关。与正常患者的正常耳朵相比，有肿瘤的耳朵的瞬态诱发耳声发射幅度（如果存在）会降低。此外，在听神经瘤患者的耳朵中，与正常患者相比，对侧耳掩蔽时观察到的幅度降低很少。然而，对侧耳掩蔽时，没有肿瘤的耳朵的幅度降低比正常患者的正常耳朵显著更大（p = 0.0006）。本文讨论了相关解剖结构以及对这些发现的可能解释。
