高頻聽力損失兒童的腦幹聽性反應與穩定狀態聽性誘發反應聽力閾值的比較

Comparison of Hearing Thresholds Assessed with Auditory Brainstem Response and Steady-State Evoked Potentials in a Group of Children with High Tone Hearing Loss

目前聽力障礙的程度是以言語頻率500Hz，1000Hz，2000Hz等三個純音聽力閾值的平均來表示，稱為平均純音聽力閾值(pure-tone threshold average, PTA) ，但並未包括4000Hz等高頻純音閾值。本研究在於以高頻聽力損失為主的病人中，比較腦幹聽性反應與穩定狀態聽性誘發反應等兩種客觀性檢查的聽力閾值與行為純音聽力檢查的聽力閾值之關係，並欲藉此得出在判定聽力為障礙時何者為較佳的客觀性生理聽力檢查。自民國89年5月至民國90年12月間，有17名高頻聽力損失為主的小孩，比共34耳。比較腦幹聽性反應閾值與純音聽力檢查的平均純音聽力閾值(PTA)，兩者的平均差是43.80± 8.60分貝(n=29)；而穩定狀態聽性誘發反應平均閾值與純音聽力檢查的平均純音聽力閾值(PTA)得平均差是15.80 ± 3.88分貝（n=34)。對純音聽力檢查的高頻(2000Hz～4000Hz)平均聽力閾值而言，其與腦幹聽性反應閾值的平均差是15.90±5.23分貝（n = 29)；而與穩定狀態聽性誘發反應的高頻(2000Hz～4000Hz)平均閾值的平均差是14.00±3.95分貝(n=31)。本研究結果顯示，雖然在高頻聽力損失的病人中，腦幹聽性反應閾值與穩定狀態聽性誘發反應，皆能有效反映出2000Hz至4000Hz的純音聽力閾值，但對於用來判定聽力障礙的基準500Hz〜2000Hz平均純音聽力閾值(PTA)而言，穩定狀態聽性誘發反應的平均閾值比腦幹聽性反應閾值更接近此值，有統計上的顯著意義(p<0.05)，因此，在需要用客親性生理聽力檢查來判定高頻聽力損失的聽力障礙程度時，穩定狀態聽性誘發反應檢查是較佳的。

Verification of pure tone audiometry is the mainstay in compensation assessment for varied degrees of hearing loss and medical-legal evaluation. Currently, calculating pure-tone threshold average (PTA) of 500Hz~2000Hz from pure-tone audiometry was used as the gold standard in evaluating hearing handicap. The purpose of this study is to compare the hearing thresholds assessed with auditory brainstem response(ABR), steady-state evoked potentials(SSEP)and pure tone audiometry in a group of children with high tone hearing loss. Seventeen children with high tone hearing loss were selected to receive ABR, SSEP and pure-tone audiometry. The mean difference between ABR thresholds and PTA was 43.80±8.60dB(n=29). The mean difference between SSEP average thresholds(500~2000Hz) and PTA was 15.80±3.88dB(n=31). The mean difference between ABR thresholds and average hearing thresholds of high tone(2000~4000Hz)of pure-tone audiometry was 15.90±5.23dB(n=29). The mean difference between average hearing thresholds of high tone(2000~4000Hz) of SSEP and pure-tone audiometry was 14.00±3.95dB(n=31). We found that ABR thresholds can only predict PTA(2000Hz~4000Hz)hearing level, but not 500Hz~2000Hz hearing level. In addition, there was strong linear correlation between pure tone audiometry and SSEP in every frequency. The present result shows SSEP was more effective in assessing the PTA of behavioral pure-tone audiometry than ABR(p<0.05). The result implied that SSEP is a better objective physiological hearing test for estimating the severity of high tone hearing loss.