Knowles Brooklynn M, MacGillivray Samantha R, Newman James A, Dennison Christopher R
Biomedical Instrumentation Lab, University of Alberta, Edmonton, AB, Canada; Department of Mechanical Engineering, University of Alberta, Edmonton, AB, Canada.
Department of Mechanical Engineering, University of Alberta, Edmonton, AB, Canada.
J Biomech. 2017 Jul 5;59:59-70. doi: 10.1016/j.jbiomech.2017.05.016. Epub 2017 May 23.
Acute subdural hematoma due to a bridging vein rupture is a devastating but rare injury. There has to date been no satisfactory biomechanical explanation for this infrequent but costly injury. We surmise that it may be associated with multiple head impacts. Though numerical models have been used to estimate vein strains in single impact events, none to date have examined the influence on localized brain strain of rapidly consecutive impacts. Using the Simulated Injury Monitor, we investigated the hypothesis that such double impacts can increase strain beyond that created by any single impact. Input to our parametric study comprised hypothetical biphasic rotational head accelerations producing a maximum angular velocity of 40rad./s. In each of 19 simulations, two identical angular inputs are applied at right angles to each other but with time separations varying from 0 to 40ms. For these double impacts, it has been generally found that strain in the region of the bridging veins is different, than what would be associated with any corresponding single impact. In some cases, the effect is to actually reduce the tissue strain. In others, the strain in the region of the bridging veins is increased markedly. The mechanistic explanation for the strain increase is that the tissue strain from the first impact has not diminished fully when strain from the second impact is initiated. Rapidly consecutive impacts could be a potential mechanism leading to vein rupture that warrants further investigation.
桥静脉破裂导致的急性硬膜下血肿是一种严重但罕见的损伤。迄今为止，对于这种不常见但代价高昂的损伤，尚无令人满意的生物力学解释。我们推测它可能与多次头部撞击有关。尽管数值模型已被用于估计单次撞击事件中的静脉应变，但迄今为止，尚无研究探讨快速连续撞击对局部脑应变的影响。我们使用模拟损伤监测器，研究了这样一种假设，即这种双重撞击会使应变增加到超过任何单次撞击所产生的应变。我们参数研究的输入包括假设的双相旋转头部加速度，其产生的最大角速度为40rad./s。在19次模拟中的每一次模拟中，两个相同的角输入相互垂直施加，但时间间隔从0到40毫秒不等。对于这些双重撞击，一般发现桥静脉区域的应变与任何相应单次撞击所产生的应变不同。在某些情况下，其效果实际上是降低组织应变。在其他情况下，桥静脉区域的应变会显著增加。应变增加的机理解释是，当第二次撞击产生的应变开始时，第一次撞击产生的组织应变尚未完全消退。快速连续撞击可能是导致静脉破裂的一种潜在机制，值得进一步研究。
