听神经瘤致聋机理——14例(16耳)听神经瘤病人听力测试结果分析

目的 :探讨听神经瘤听力损失的病理生理机制。方法 :对 14例 (16耳 )听神经瘤患者行纯音听阈、阻抗、听性脑干反应 (ABR)、诱发耳声发射测试 (EOAE)及 CT和 (或 ) MRI扫描。 EOAE能引出的 4耳还检测其传出抑制功能 ,ABR不能检测且 EOAE不能引出的重度聋 (听力损失大于 80 d B)有 5耳行鼓岬刺激试验 (PST)。结果 :16耳听神经瘤中2耳 (12 .5 0 % )听力损失源于神经性损害 ;6耳 (37.5 0 % )蜗性损害 ;8耳 (5 0 % )蜗 -神经性损害。能引出 EOAE的 4耳均有传出功能障碍。结论 :EOAE可评价听神经瘤的耳蜗功能状态 ;ABR结合 PST能分析听神经瘤的蜗后神经功能。听神经瘤的听觉病理可同时或单独发生于听外周的耳蜗水平、第 对颅神经 (传入神经 )水平和橄榄核耳蜗传出神经水平。

Auditory tests in 14 patients(16 ears)with acoustic neuroma

Objective:To investigate the relationship between hearing loss and acoustic neuroma(AN),the tests of pure tone audiometry,acoustic emissions impedance audiometry,audiometry brainstem response(ABR)and evoked otoacoustic emissions(EOAE)wee measured in 14 patients (16 ears)from March 1999 to December 2000.Methods:Fourteen patients (16 ears)with acoustic neuroma (8 males and 6 females,ranging in age from 21 to 72 years old)were diagnosed by CT or MRI scaning,and final confirmed by surgery and pathology.In the auditory tests ,efferent suppression test was curried out only in 4 ears with recordable emissions,promontory stimulation test (PST)was examined only in 5 ears with severe or profound deafness (hearing loss≥80dB SPL)who have no both measurable ABR and recordable EOAE.Results:It was found that 2 ears (12.5%,2/16)of the AN ears showed neural impairment,6 ears (37.5%,6/16)were cochlear impairment and 8 ears (50.0%,8/16)were cochlear-retrocochlear impairment.All of 4 tumors ears with EOAE emission have a disorders of efferent function.Conclusion:EOAE test had significant value for evaluation of the status of cochlear function (at the level of outer hair cells)in AN patients.The retrocochlear auditory nerve function of AN patients were evaluated by the tests of ABR combined PST which showed significant value.Results showed that the hearing impairment of AN have different levels of the peripheral auditory system according to auditory tests,including cochlear,eighth cranial nerve and efferent nerve level at the same or independently.