Department of Mechanical, Aerospace and Structural Engineering, St Louis, MO 63130, USA.
J R Soc Interface. 2010 Dec 6;7(53):1677-88. doi: 10.1098/rsif.2010.0210. Epub 2010 May 26.
This study describes the measurement of fields of relative displacement between the brain and the skull in vivo by tagged magnetic resonance imaging and digital image analysis. Motion of the brain relative to the skull occurs during normal activity, but if the head undergoes high accelerations, the resulting large and rapid deformation of neuronal and axonal tissue can lead to long-term disability or death. Mathematical modelling and computer simulation of acceleration-induced traumatic brain injury promise to illuminate the mechanisms of axonal and neuronal pathology, but numerical studies require knowledge of boundary conditions at the brain-skull interface, material properties and experimental data for validation. The current study provides a dense set of displacement measurements in the human brain during mild frontal skull impact constrained to the sagittal plane. Although head motion is dominated by translation, these data show that the brain rotates relative to the skull. For these mild events, characterized by linear decelerations near 1.5g (g = 9.81 m s⁻²) and angular accelerations of 120-140 rad s⁻², relative brain-skull displacements of 2-3 mm are typical; regions of smaller displacements reflect the tethering effects of brain-skull connections. Strain fields exhibit significant areas with maximal principal strains of 5 per cent or greater. These displacement and strain fields illuminate the skull-brain boundary conditions, and can be used to validate simulations of brain biomechanics.
本研究通过带标记的磁共振成像和数字图像分析，描述了活体大脑和颅骨之间相对位移场的测量。大脑相对于颅骨的运动发生在正常活动中，但如果头部受到高加速度的影响，神经元和轴突组织的大而快速变形会导致长期残疾或死亡。加速性创伤性脑损伤的数学建模和计算机模拟有望阐明轴突和神经元病理学的机制，但数值研究需要了解大脑-颅骨界面的边界条件、材料特性和实验数据进行验证。本研究在约束在矢状面内的轻度额骨冲击下，提供了人类大脑中密集的位移测量值。尽管头部运动主要是平移，但这些数据表明大脑相对于颅骨旋转。对于这些轻度事件，其特征是接近 1.5g（g = 9.81 m s⁻²）的线性减速和 120-140 rad s⁻²的角加速度，典型的相对脑-颅骨位移为 2-3 毫米；较小位移的区域反映了脑-颅骨连接的束缚效应。应变场显示出具有 5%或更大最大主应变的显著区域。这些位移和应变场阐明了颅骨-脑边界条件，并可用于验证脑生物力学的模拟。
