低频旋转乳突振动对正常志愿者听力的影响

摘要

Objective To evaluate the safety of a newly designed rotatory low-frequency mastoid vibration system with respect to the auditory system. Methods Twelve normal volunteers without vertigo were enrolled in the study, including 10 males and 2 females, aged from 23 to 25 years. The vibrator was placed on the right mastoid process with assistance of a special holder. The vibration lasted for 30 minutes. Pure-tone audiometry was performed on both sides before and at 30 minutes, 1 week, and 1 year after exposure to the rotatory low-frequency vibrations. Thresholds at different frequencies at various times post-vibration exposure were compared to the thresholds before exposure using the Wilcoxon signed rank test. Results At 30 minutes after vibration exposure, there was a significant improvement in bone conduction hearing threshold at 0.25, 0.5 and 1 kHz (3, 5 and 3 dB threshold decrease respectively) in ears that had been exposed to the vibration (p<0.05). At 7 days after vibra⁃tion exposure, a significant decrease in the air-conduction threshold in the contralateral ear at 0.25 kHz and 0.5 kHz was record⁃ed (p<0.05). At 1 year after exposure, there were controversial changes in the exposed ear, showing a 6 dB decrease at 0.25 and 0.5 kHz (p<0.05) and a 10 dB increase at 8 kHz (p<0.01) in air conduction threshold, but a increase at 0.25, 0.5 and 1 kHz in bone-conduction threshold (8, 3 or 4 dB respectively) (p<0.01 or 0.05, Wilcoxon test). There appeared to be air conduction hear⁃ing loss at 4 and 8 kHz (7 and 10 dB threshold increase respectively) and bone conduction loss at 0.25 through 4 kHz (7, 6, 6, 8 and 8 dB threshold increase at each tested frequency respectively) in the contralateral ear. Conclusion There is no clear pattern in the small hearing threshold change shortly after exposure to rotatory low frequency mastoid vibration. The changes seen at 1 year after exposure are not consistent with typical vibration-induced hearing threshold change. Therefore, the rotatory low-fre⁃quency mastoid vibration system for vertigo therapy is safe to the auditory system.%目的：我们设计了一种新颖的治疗眩晕低频旋转乳突振动设备，本研究是为了评估该设备对听觉系统的安全性。方法选12名无眩晕主诉的志愿者，男性10例，女性2例，年龄23-25岁。将低频振动投放于右侧乳突，分别于振动前、振动后0.5小时、7天、和1年行纯音听阈检测，分析比较双耳的不同频率气、骨导阈值的变化。结果受试者双耳在低频振动后0.5小时的，右耳（暴露耳）在0.25、0.5、1.0 kHz骨导听阈分别降低了3、5、3 dB，有显著性差异（p＜0.05），气导阈移无显著性差异；振动后7天，左耳（对照耳）在0.25、0.5 kHz气导听阈分别提高了3、2 dB，有显著性差异（p＜0.05）；振动后1年右耳在0.25、0.5、8kHz气导听阈分别降低了6、6、9 dB，在0.25、0.5、1 kHz骨导听阈分别升高了7、3、4 dB，均有显著性差异（p＜0.05），左耳在2、4、8 kHz气导听阈分别提高了6、6、10 dB，在0.25、0.5、1、2、4kHz骨导听阈分别升高了7、6、6、8、8 dB，均有显著性差异（p＜0.05）。结论振动后0.5小时及7天的听阈变化无规律，且数值小，无临床意义；1年后的左耳听阈升高6-10 dB，右耳低频气导听阈降低，低频骨导听阈提高，不符合振动引起的特异性改变，因此，该治疗眩晕的低频乳突振动设备对听觉系统是安全的。