頻譜差聲反射檢查與聲阻鼓室圖對於偵測中耳積液之比較

Comparison of Spectral Gradient Acoustic Reflectometry and Tympanometry for Detection of Middle Ear Effusion

1999年8月至2000年10月間，於台大醫院耳鼻喉部因診斷為中耳積液而接受中耳通氣管置入或鼓膜切開手術的患者，共計95名186耳，其中男性63名，女性32名，年齡分佈從1歲6個月到19歲7個月，平均年齡6歲6個月，於手術直前均施行頻譜差聲反射檢查（spectral gradient acoustic reflectometry, SG-AR）和聲阻鼓室圖檢查（tympanogram）。依頻譜差聲反射檢查結果將受檢耳分為頻譜差角（spectral gradient angle） >95°、70～95°、60～69°、49〜59°和<49°等5組，手術時證實有中耳積液比率分別為4%、50%、100%、100%、100%，在小於6歲與6～20歲組間並無明顯差異。聲阻鼓室圖A、C1、C2，B1、B2型各組手術時證實有中耳積液的比率分別為0%、57%、74%、77%、96%。本研究結果顯示頻譜差聲反射檢查的確較聲阻鼓室圖對於偵測中耳積液有著較佳的效度。若以通常採用的鼓室圖呈現B或C2型為診斷中耳積液的標準，則鼓室圖檢查的靈敏度為96%、特異度38%；頻譜差聲反射檢查若以頻譜差角<70°作為診斷中耳積液的標準，則在不明顯降低診斷中耳積液的靈敏度（92%）下，可大大提高此種檢查診斷中耳積液的特異度至100%，如此可以避免非必要的鼓膜切開手術。我們的經驗建議施行頻譜差聲反射檢查時，測量時受測耳的位置應較低，且改變探頭位置與方向並多次測量，則能提升頻譜差聲反射檢查的效度。

Spectral gradient acoustic reflectometry (SG-AR) and tympanometry in diagnosing middle ear effusion (MEE) were validated. From Aug 1,1999 to Oct 1, 2000, myringotomy under microscopy with or without ventilating tube insertion was performed in 186 ears of 95 patients under the diagnosis of middle ear effusion. Tympanometry and SG-AR were examined for all ears one day before myringotomy. The results showed that, the incidence of MEE for type A, C1, C2, B1, and B2 tympanograms were 0%, 57%, 74%, 77%, 96%, respectively. Corresponding values for SG-AR level 1 to 5 were 4%, 50%, 100%, 100% and 100%, respectively, The results demonstrated that tympanometry, when validated by myringotomy finding under microscopy, detected MEE with 96% sensitivity, and 38% specificity when type B and C2 were considered as evidence of MEE. Corresponding values for SG-AR were 92% and 100% when a cut-off of a 70-degree spectral gradient angle was used. The present results were somewhat different from those of earlier studies and demonstraled that the test efficacy and ease of use of SG-AR was better than tympanometry for detecting MEE. It is our exprience that the test efficacy of SG-AR would be increased if we keep the tested ears at a lower position ami make the multiple measurements by changing the position and direction of the probe tip of the instrument while performing examination with SG-AR.