BASIC AND CLINICAL RESEARCH ON MECHANISMS OF TINNITUS IN ACOUSTIC

为了阐明听神经瘤耳鸣的发病机制，我们研究了瞬态诱发耳声发射（TEOAEs），它反映了与外毛细胞主动运动特性有关的耳蜗微力学。包括外毛细胞在内的耳蜗传出神经系统的功能障碍被认为是耳鸣的发病机制之一。本文对95例听神经瘤患者和50例梅尼埃病患者进行了TEOAE检测，以探讨耳蜗性和耳蜗后性听力障碍患者的听力水平与TEOAE的关系。能获得TEOAE的听神经瘤患者的平均听力水平为28.4（±）SY。梅尼埃病组为28.3 ± 0.5dB。[）12.5dB。虽然有3例听神经瘤患者的听力损失超过60dB，但TEP（TEOAE参数之一）与健侧相比仍有恶化。从这些结果中，我们得出结论， ...更多信息 认为几乎所有听神经瘤患者都有耳蜗受累。因此，正常的TEOAEs在伴有中重度听力障碍的听神经瘤患者中并不常见。本文对85例单侧听神经瘤行中颅窝入路或扩大中颅窝入路Ⅲ型保听手术的患者，分析了手术前后耳鸣的发生情况。其中成功保留听力者37例，听力损失者48例。听力保留组与听力损失组耳鸣改善或加重的差异无统计学意义。听神经瘤患者对耳鸣性质的主观表现多种多样，因此，对耳鸣预后的推测被认为是困难的，但两例听神经瘤患者的耳鸣大多是轻微的，对他们的生活质量没有那么痛苦。少

In order to clarity the mechanisms of tinnitus in acoustic neuroma, we investigated the transient evoked otoacoustic emissions (TEOAEs) which reflect the cochlear micromechanics related to the active motile property of outer hair cells. Dysfunctions of the cochlear efferent nervous system including the outer hair cells have been postulated as one of the mechanisms of tinnitus. We recorded TEOAEs in 95 acoustic neuroma patients and 50 Meniere's disease patients as controls in order to clarify the relationship between the hearing level and TEOAEs in cochlear and retrocochlear hearing impairments. Mean hearing level of the acoustic neuroma patients whose TEOAEs could be obtained was 28.4(]SY.+-。[)14.6dB and that of the Meniere's disease patients was 28.3(]SY.+-。[)12.5dB.Although there were 3 acoustic neuroma patients with TEOAE in spite of hearing impairment over 60 dB,deterioration in TEP (one of the TEOAE parameter) was found compaing with healthy side ear. From these results, we conclu … More ded that there must be an affection to the cochlea in almost all acoustic neuroma patients. Thus, the normal TEOAEs seem to be uncommon in the acoustic neuroma patients with mederate or severe hearing impairment.We also conducted the study on the nature of tinnitus in acoustic neuroma. A series of 85 patients who had undergone hearing-preserved operation (the middle cranial fossa approach or the extended middle cranial fossa approach type III) of a unilateral acoustic neuroma was analyzed about pre and postoperative tinnitus. They consisted of 37 successful hearing-preserved cases and 48 hearing-loss cases. Obvious differences between hearing-preserved cases and hearing-loss cases were not found about improvement or worse of their tinnitus. Subjective expressions of tinnitus nature among acoustic neuroma patients were various, therefore, it was thought that a speculation about prognosis of tinnitus will be difficult, but tinnitus of acoustic neuroma patients in both cases was mostly mild and not so painful for their quality of life. Less