脳血管障害患者における音の方向覚障害の経時変化

Natural course of the disturbance of sound localization in stroke patients

要旨：脳血管障害患者における音の方向覚障害の経時変化はこれまで知られていないので，われわれの結果を報告する．

　脳血管障害左片麻痺患者14名，右片麻痺患者6名を対象に，入院時と入院後平均2.5ヵ月時の2回，音方向覚検査を行った．ヘッドホン音像定位システムを使用し，患者前方で30°間隔の7方向からランダムに音を提示し，提示方向と回答方向との絶対的ずれを集計した．左片麻痺患者群の左聴野で絶対的ずれの小さくなる傾向があったものの，左片麻痺患者群，右片麻痺患者群いずれにおいても有意な経時変化は認められなかった．

　今回の患者は入院時の絶対的ずれが総じて軽度であったため，有意な経時変化が得られなかった可能性が考えられた．

　The natural course of the disturbance in localizing sound in stroke patients has not been reported. This study included 20 stroke patients who were admitted to our hospital (left hemiplegia, 14 ; right hemiplegia, 6). The ability of sound localization was tested in each patient using a headphone and sound space processor system during the admission and at a mean of 2.5 months after the admission. Sounds were randomly presented from 7 directions in the 180-degree frontal area of the subject at intervals of 30 degrees. Following each sound, the subject indicated the direction from which he/she thought the sound came. The mean absolute error between the presented and answered directions was calculated for each patient.

　The mean absolute error of sound localization at admission, and that at 2.5 months after the admission among the patients with left hemiplegia and among those with right hemiplegia, did not significantly differ. However, in the patients with left hemiplegia, the mean absolute error to sounds presented in the left auditory field was lower at 2.5 months after the admission in comparision with that at admission, although the difference was not statistically significant.

　The lack of a significant improvement in sound localization in these stroke patients may be due to the fact that none of these stroke patients had severe disturbance of sound localization on admission.