Brain/skull relative displacement magnitude due to blunt head impact: new experimental data and model
Brain/skull relative displacement magnitude due to blunt head impact: new experimental data and model
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DOI：
10.4271/99sc22
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发表时间：
1999-10
影响因子：
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通讯作者：
A. S. Al-Bsharat;W. Hardy;King H. Yang;T. Khalil;S. Tashman;A. King
中科院分区：
文献类型：
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作者：
A. S. Al-Bsharat;W. Hardy;King H. Yang;T. Khalil;S. Tashman;A. King
脑和颅骨之间的相对运动可以解释许多类型的脑损伤，例如由于桥静脉破裂和脑挫伤引起的脑内血肿。然而，还没有实验方法来测量这种运动的大小。因此，分析工具预测的大脑和头骨之间的相对运动从未得到验证。在本研究中，将不透射线标记物放置在颅骨中，并将中性密度标记物放置在大脑中枕顶和颞顶区域的两个垂直柱中。双平面高速X射线系统用于跟踪这些标记的运动。由于目前在高速摄像机上记录X射线图像的技术有限，只能获得低速（<4米/秒）撞击的数据。一个以前开发的有限元模型的大脑模拟钝头碰撞被用来研究的可行性，使用这个模型，以获得相同幅度的相对位移的实验获得。该模型模拟头皮、三层颅骨、硬脑膜、大脑镰、小脑幕、软脑膜、脑脊液（CSF）、静脉窦、脑室、大脑（灰质和白色物质）、小脑、脑干和小脑旁桥静脉。模型的任何组件结构之间不允许滑动，并且使用具有低剪切模量的固体单元层来模拟CSF。然而，这种方法无法预测大脑和颅骨之间超过1 mm的相对运动。在这项研究中，模型进行了修改。虽然CSF仍然是一层具有低剪切模量的材料，但引入滑动界面来模拟CSF和软质之间的相互作用。随着这种变化的发生，模型预测与从尸体实验中获得的脑位移数据相对应。新模型预测的相对颅骨/脑位移-时间历程与实验结果吻合良好。该模型还在更高的冲击速度下运行，以获得颅内压以及位移历史。该模型预测的碰撞/对冲压力和接触力的计算结果与Nahum等人发表的实验数据进行了比较。模拟结果再现了Gurdjian和利斯纳提出的平移加速度损伤机制（碰撞/对冲）。
Relative motion between the brain and skull may explain many types of brain injury such as intracerebral hematomas due to bridging veins rupture and cerebral contusions. However, no experimental methods have been developed to measure the magnitude of this motion. Consequently, relative motion between the brain and skull predicted by analytical tools has never been validated. In this study, radio opaque markers were placed in the skull and neutral density markers were placed in the brain in two vertical columns in the occipitoparietal and temporoparietal regions. A bi-planar high-speed x-ray system was used to track the motion of these markers. Due to limitations in current technology to record the x-ray image on high-speed video cameras, only low speed (<4m/s) impact data were available. A previously developed finite element model of the brain simulating blunt head impact was used to study the feasibility of using this model to obtain relative displacement of the same magnitude as that obtained experimentally. The model simulated the scalp, three-layered skull, dura, falx, tentorium, pia, cerebral spinal fluid (CSF), venous sinuses, ventricles, cerebrum (gray and white matter), cerebellum, brain stem, and parasagittal bridging veins. No sliding was allowed between any component structures of the model, and a layer of solid elements with low shear modulus was used to model the CSF. However, this approach was not able to predict relative motions over 1 mm between the brain and skull. In this study, the model was modified. Although the CSF remained as a layer of material with a low shear modulus, a sliding interface was introduced to simulate the interaction between the CSF and pia matter. With this change in place, the model predictions corresponded with brain displacement data obtained from cadaveric experiments. The relative skull/brain displacement-time histories predicted by the new model agreed well with those obtained experimentally. The model was also run at higher impact speeds to obtain intracranial pressure as well as displacement histories. The computed coup/contrecoup pressures and contact forces predicted by the model compared favorably with the experimental data published by Nahum et al. Simulation results reproduced the translational acceleration injury mechanism (coup/contrecoup) proposed by Gurdjian and Lissner.