闭合性颅脑损伤后大鼠BAEP及脑损伤的动态变化

Dynamic Observation of Brainstem Auditory Evoked Potential and Pathological Changes of the Brain after Closed Brain Injuries in Rats.

目的观察大鼠闭合性弥漫性颅脑损伤后脑干听觉诱发电位(BAEP)的动态改变及脑组织病理学变化,探讨BAEP在颅脑损伤后评估听觉功能障碍的价值。方法使用自制弹簧式小型生物打击机打击大鼠颅顶部,制造闭合性弥漫性轻型颅脑损伤模型。观察对照组以及伤后15min和1,3,6,12h及1,2,4,7,10,14,21d等时间点大鼠脑组织病理学改变,干/湿法检测脑组织含水量。分别于伤前、伤后各时间点以50Hz刺激率记录大鼠BAEP,对其结果进行比较。结果损伤后15min,BAEP的Ⅰ～Ⅴ、Ⅲ～ⅤIPL即较损伤前延长(P<0.05),至6～12h,Ⅲ、ⅤPL较损伤前延长。损伤后1～2d,Ⅲ、ⅤPL和Ⅰ～Ⅲ、Ⅰ～Ⅴ、Ⅲ～ⅤIPL均较损伤前显著延长(P<0.001),14d后BAEP逐渐恢复正常。伤后15min脑组织含水量开始升高,伤后1d达高峰,持续至4d后逐渐下降,至10d后降至正常水平。结论BAEP可作为闭合性弥漫性轻型颅脑损伤后听觉功能障碍的客观评价指标。

Objective To investigate the dynamic experiences of pathological changes in brain and the injured role of brainstem auditory evoked potential （BAEP） after closed Mild Traumatic Brain Injury （MTBI） in rat. Methods A closed diffuse brain injury model was successfully produced in rat by hit the parietal bone with a spring-droved steel stick. The auditory brainstem response evoked by click at 50Hz stimulating frequency were recorded at pre-trauma, 15 min and 1,3,6,12hand 1,2,4,7,10,14,21 d after brain injury. The pathological changes of brain were observed under light microscope and the brain edema was detected by wet weight/dry weight rations. Results The Ⅰ-Ⅴ, Ⅲ- Ⅴ of BAEP wave inter peak latency （IPL） in MTBI group increased immediately in 15 minutes after injury. The Ⅲ, Ⅴ wave peak latency （PL） and Ⅰ-Ⅴ, Ⅲ-Ⅴ wave IPL became longer than the pre-trauma level in 6, 12h post-injury （P〈0.05）. The 11, Ⅴ wave PL and Ⅰ-Ⅲ, Ⅰ-Ⅴ, Ⅲ-Ⅴ wave IPL became longer than the pre-trauma level in 1, 2d after injury（P〈0.001）, the BAEP retuned to normal level in 14d after brain injury. At 15 minutes after injury, the water content in brain increased and met its peak in 1 d, decreased gradually in 4d, then decreased slowly and returned to normal level in 10d after injury. Conclusion The regular changes of BAEP could be an objective tool for evaluating hearing dysfunction after closed mild diffuse traumatic brain injury.