ASSESSMENT OF DIRECTIONAL HEARING ABILITY IN PATIENTS WITH CEREBROVASCULAR DISORDER

• Published in: Journal of The Showa Medical Association Vol. 49; no. 6; pp. 573 - 581
• Main Author: AKAIKE Hiroshi
• Format: Journal Article
• Language: English
• Published: 昭和大学学士会 1989; The Showa University Society
• Subjects: directional hearing ability; retro cochleal deafness; self-recording method; 両耳間時間差; 方向感; 脳血管障害; 自記法変法
• ISSN: 0037-4342; 2185-0976
• DOI: 10.14930/jsma1939.49.573

Directional hearing ability test is one of the essential methods in diagnosing retrocochlear deafness. A new directional hearing ability test apparatus, Model TD-01, has been used to test patients with unilateral hemicerebrum disorder due to cerebrovascular disorders such as cerebral hemorrhage and cerebral infarction. Testing was by a self-recording method, which is a modification of the manipulatory technique of a previous self-recording method, plus a conventional manual method and another self-recording method. This new apparatus produces time differences at random from a minimum of 2μsec to a maximum of 2 msec, without distortion, from an optional sound source. Compared with the conventional self-recording method, more precise judgement is now possible by the modified method we have devised to simplify the manipulation by the patient. The subjects were patients with hemiplegia in whom the disordered sites were distinguished by CT, etc., and whose symptoms were evident. For testing, they were divided into 27 cases for stage I and 27 for stage II . For comparison, a similar test was performed concurrently on normal subjects. The result: revealed significant differences between the left hemiplegia group, and the normal subjects, The self-recording method and the modified method were closely correlated in the left hemiplegia group, but not in the right hemiplegia group. From the results, the modifiec self-recording method was found to be more useful for judgement of derectional hearing ability in the hemiplegia patients tested, and the superior ability of the right hemicerebrurc to determine hearing direction was suggested by the larger number of cases in the left hemiplegia group in whom directional hearing ability was deteriorated. 音の方向感検査は, 中枢性難聴を診断する上での重要な一方法である.そこで, 脳出血, 脳梗塞などの脳血管障害による一側大脳半球障害者を対象に, 新しい方向感検査装置TD-01を用いて方向感検査を行った.検査方法には, 従来行われている手動法, 自記法に加え, 自記法の手法を変更した自記法変法を用いて行った.本器は, 任意の音源について無ひずみのまま最小2μsecより最大2msecまでの時間差を任意に作り出すことができ, 時間差は2, μsec単位で増減することができる.被検者のスイッチ操作によって, 音像の移動方向が瞬時に反転するとともに, 両耳間時間差の軌跡が自動的に記録される.すなわち, 本機器により動的な方向感検査が可能である.われわれが考案した自記法変法は, 従来の自記法に比較して患者側の操作を単純化することにより, より正確な判定が可能になった.対象は症状のはっきりした片麻痺患者で第1期27例, 第2期27例に分けて検査を行った.同時に, 正常人に同様の検査を行い比較を行った.評価法としては, グラフにおける振幅の平均値と標準偏差値をもって方向感の指標とした.結果は, 正常人に比較して左片麻痺群で有意差を認め, 右片麻痺群とは有意差を認めなかった.また, 自記法と自記法変法との相関をみると, 左片麻痺群ではやや高い相関を認めたが, 右片麻痺群では相関を認めなかった.以上より, 対象とした片麻痺症例の方向感機能の判定には自記法変法が非常に有用であり, 左片麻痺群に方向感の悪化する例が多いことにより, 方向感の右大脳半球優位性が示唆された.