Smith Kyle D, Chen Tao, Gan Rong Z
School of Aerospace and Mechanical Engineering, University of Oklahoma, 865 Asp Avenue, Norman, OK 73019.
Mil Med. 2020 Jan 7;185(Suppl 1):248-255. doi: 10.1093/milmed/usz309.
The peripheral auditory system and various structures within the central auditory system are vulnerable to blast injuries, and even blast overpressure is at relatively mild traumatic brain injury (TBI) level. However, the extent of hearing loss in relation to blast number and time course of post-blast is not well understood. This study reports the progressive hearing damage measured in chinchillas after multiple blast exposures at mild TBI levels (103-138 kPa or 15-20 psi).
Sixteen animals (two controls) were exposed to two blasts and three blasts, respectively, in two groups with both ears plugged with foam earplugs to prevent the eardrum from rupturing. Auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) were measured in pre- and post-blasts. Immunohistochemical study of chinchilla brains were performed at the end of experiment.
Results show that the ABR threshold and DPOAE level shifts in 2-blast animals were recovered after 7 days. In 3-blast animals, the ABR and DPOAE shifts remained at 26 and 23 dB, respectively after 14 days. Variation of auditory cortex damage between 2-blast and 3-blast was also observed in immunofluorescence images.
This study demonstrates that the number of blasts causing mild TBI critically affects hearing damage.
外周听觉系统以及中枢听觉系统内的各种结构易受爆炸伤影响，甚至爆炸超压处于相对轻度的创伤性脑损伤（TBI）水平。然而，关于听力损失程度与爆炸次数及爆炸后时间进程之间的关系，目前尚不清楚。本研究报告了在轻度TBI水平（103 - 138kPa或15 - 20psi）下多次爆炸暴露后，对龙猫进行测量得到的渐进性听力损伤情况。
16只动物（2只为对照）分为两组，分别接受两次爆炸和三次爆炸暴露，双耳均插入泡沫耳塞以防止鼓膜破裂。在爆炸前后测量听觉脑干反应（ABR）和畸变产物耳声发射（DPOAE）。实验结束时对龙猫大脑进行免疫组织化学研究。
结果显示，接受两次爆炸暴露的动物，其ABR阈值和DPOAE水平变化在7天后恢复。在接受三次爆炸暴露的动物中，14天后ABR和DPOAE变化分别仍为26dB和23dB。在免疫荧光图像中也观察到两次爆炸和三次爆炸组之间听觉皮层损伤的差异。
本研究表明，导致轻度TBI的爆炸次数对听力损伤有至关重要的影响。
