应用40Hz听觉事件相关电位和听觉脑干诱发电位客观评定听阈的研究

目的探讨40Hz听觉事件相关电位(40Hz AERP)与听觉脑干诱发电位(ABR)联合应用在法医学上的意义。方法 纯音测听结果可信86耳,分为听力正常组62耳,听力障碍组24耳。40Hz AERP用短纯音,刺激频率0.5kHz、1kHz、2kHz、4kHz。20耳进行自然睡眠及清醒两种状态下反应阈测定。ABR用短声(Click)。结果 86耳40Hz AERP引出率为97.67％,ABR为95.35％。听力正常组及听力障碍组40Hz AERP反应阈均较纯音测听气导主观听阈高,在不同的频率二者差值不同,两组差值的均值无显著性差异。四个频率40Hz AERP和ABR反应阈与主观听阈回归方程的r,前者分别为0.90、0.89、0.78、0.79,后者分别为0.54、0.58、0.60、0.83。自然睡眠状态Pa-Na波的波幅明显降低,反应阈值提高。用听力障碍组反应阈代入四个回归方程,预估值与实测值接近,差值小于20dB。结论 40Hz AERP可以客观反映言语频率范围(0.5～2kHz)的听觉状况,ABR可以客观评定高频范围的听阈;通过回归方程可以用40Hz AERP和ABR反应阈客观评定听力状况;联合应用40Hz AERP和ABR可以提高客观评定听阈的准确性。

The forensic medicine study of objective auditory function by 40Hz auditory event - related potential and auditory brainstem induced response

Objective It has been explored whether characteristic frequency may be recorded by 40Hz event - related potential (40Hz AERP) , and auditus of high frequency by auditory brainstem response (ABR). In the present study, the application of 40Hz AERP in combination with ABR was conducted for evaluation of auditus. Methods Credible 86 ears as proved by audiometory were divided into control group (62ears) and auditory abnormali group (24ears). 40Hz AEPP was evoked with short pure tone at frequencies of 0. 5kHz, 1kHz, 2kHz and 4kHz. In control group, 20 of 62 ears received threshold test under natural sleeping and waking, conditions respectively. ABR was evoked with click sound. Results 40Hz AERP were elicited in 97. 6% of the 86 ears and ABR 95. 35%. Response threshold evaluated by 40Hz AEPP was higher than subjective auditory threshold as tested by audiometry in both groups. The threshold value differs with given different frequencies. No signification difference was found between the average value differences in either groups. Correlation Coefficients of regression equations regarding 40Hz AERP response threshold and subjective auditory threshold tested by audiometry were 0. 90, 0. 89, 0. 78 and 0. 79, whereas those of ABR were 0. 54, 0. 58, 0. 60 and 0. 83. The results showed that Pa - Na wave swing in 16ears under sleep dramatically lowered and the value of response threshold elevated. When the response threshold were fed into the four equations, the average value of subjective auditory threshold was similar to the estimated one, and the differences of estimated value and tested one were mostly lower then 20dB. Conclusion 40Hz AERP could be used for evaluation response threshold of vocal frequency (0. 5 ~ 2kHz) , ABR for evaluation of response threshold of higher frequency objectively; Hearing condition could be evaluated by use of 40 Hz AERP and ABR response threshold calculation by regression equation. More accurate and objective auditory threshold could be ob- tained with 40Hz AERP in combination with ABR.