急进高原轻-中度闭合性颅脑损伤后在不同海拔下伤情变化的观察

目的观察急进高原地区轻-中度闭合性颅脑损伤(mmCHI)急性期转运至不同海拔高度下的伤情变化。 方法平原饲养的健康雄性SD大鼠称基础体质量，模拟海拔6.0 km持续低压、低氧处理24 h后再次称质量，采用气动式撞击装置制作mmCHI模型，观察大鼠致伤后生命体征变化并进行神经功能缺损评分（NSS），随机分为不同海拔高度组（6.0、4.5、3.0 km）进行观察，并分别对相应海拔高度下大鼠在mmCHI后6、12、24 h的NSS评分、体质量、脑含水量、脑含水量与体质量的比值及颅脑MRI检查。 结果急进高原mmCHI大鼠在致伤后6 h各海拔高度组NSS评分减少值明显低于伤后12、24 h评分减少值（P<0.05）；伤后快速下降至3.0 km组大鼠体质量下降最少，与伤后滞留于6.0 km及下降至4.5 km组比较，差异具有显著统计学意义（P<0.05）；伤后脑含水量各组比较差异无统计学意义；伤后下降至4.5 km大鼠的脑含水量占体质量的百分比最低，与其他2组比较差异具有显著统计学意义（P<0.05）；动态MRI定量检测分析结果显示伤后下降至4.5 km大鼠的胼胝体水肿及脑室扩张程度明显低于其他海拔高度（P<0.05）。 结论极高海拔环境下mmCHI后早期、阶梯式转运至低海拔地区可减轻继发性颅脑损伤。高原颅脑损伤后早期MRI检查可对预后判断及临床诊治有指导意义。

Injury changes in mild-to-moderate closed head impact injury at different altitudes after acute high altitude exposure

ObjectiveTo explore the pathophysiological changes in mild-to-moderate closed head impact (mmCHI) injury at different altitudes after acute high altitude exposure. MethodsThe basal body weight of Male Sprague-Dawley rats grown in plain environment was recorded and was remeasured after undergoing simulated 6000 m altitude of continuous low pressure and hypoxia for 24 h. Pneumatic impact device was used to afflict mmCHI injury. The changes in vital signs of injured rats were observed and neurological severity score (NSS) was obtained. The group was then further divided and observed at different altitudes (6000, 4500, 3000 m). The NSS of rats at 6, 12 and 24 h after mmCHI were recorded respectively at corresponding altitudes, together with their body weight, brain magnetic resonance imaging (MRI), brain water content changes and brain water content to body weight ratio. ResultsThe reduction of NSS score at 6 h after mmCHI was significantly lower than at 12 h and 24 h after injury, the difference was statistically significant (P<0.05). After mmCHI, minimal weight loss was observed among animal group rapidly descending to 3000 m. However, significant difference was found when compared to rat groups that remained at 6000 m and those descending to 4500 m altitude (P<0.05). There was no significant difference in brain water content between the groups after injury; Compared to together two groups the ratio of the brain water content to the body weight (BWC/BW) is the lowest in animal groups which descended from 6000 m to 4500 m. The difference was statistically significant when compared to other two groups (P<0.05). The results of dynamic MRI quantitative analysis showed that the degree of corpus callosum swelling and dilation of ventricles in 4.5 km group after mmCHI were significantly lower than those at other altitudes (P<0.05). ConclusionTranslocated as early as possible, and fast step-by-step descension to lower altitudes can relieve secondary brain injury after extreme high altitude mmCHI. The examination of MRI may have reference to determine prognosis and clinical in altitude mmCHI.