Maikos Jason T, Elias Ragi A I, Shreiber David I
Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey.
J Neurotrauma. 2008 Jan;25(1):38-51. doi: 10.1089/neu.2007.0348.
The dura mater is the outermost and most substantial meningial layer of central nervous system (CNS) tissue that acts as a protective membrane for the brain and spinal cord. In animal models of traumatic brain injury and spinal cord injury, mechanical insults are often delivered directly to the dura to injure the underlying tissue. As such, including a description of the mechanical properties of dura mater is critical for biomechanical analyses of these models. We have characterized the mechanical response of dura mater from the rat brain and spinal cord in uniaxial tension. Testing was performed at low (0.0014 sec(-1)) and high (19.42 sec(-1)) strain rates. Both rat cranial dura and spinal dura demonstrated non-linear stress-strain responses characteristic of collagenous soft tissues. The non-linear increase in stress lagged in the spinal dura compared to the cranial dura. The slow rate data was fit to a one-term Ogden hyperelastic constitutive law, and significant differences were observed for the stiffness, G, and the parameter, alpha, which nominally introduces non-linearity. High strain rate stress-relaxation tests were performed to 10% strain, which was held for 10 sec. The relaxation was fit to a four-term Prony series exponential decay. Cranial dura and spinal dura demonstrated similar overall relaxation, but significant differences were identified in the distribution of the relaxation over the Prony series parameters, which demonstrated that cranial dura tended to relax faster. Polarized light microscopy revealed that the structural entities of spinal dura were aligned in the axial direction, whereas cranial dura did not demonstrate a preferential alignment. This was confirmed qualitatively with Masson's Tri-chrome and Verhoeff's Van Gieson staining for collagen and elastin, which also indicated greater elastin content for the spinal dura than for the cranial dura.
硬脑膜是中枢神经系统（CNS）组织最外层且最厚实的脑膜层，对脑和脊髓起到保护膜的作用。在创伤性脑损伤和脊髓损伤的动物模型中，机械损伤常常直接作用于硬脑膜以损伤其下方的组织。因此，描述硬脑膜的力学特性对于这些模型的生物力学分析至关重要。我们已经对大鼠脑和脊髓的硬脑膜在单轴拉伸下的力学响应进行了表征。测试在低（0.0014秒-1）和高（19.42秒-1）应变率下进行。大鼠的颅硬脑膜和脊髓硬脑膜均表现出胶原性软组织特有的非线性应力-应变响应。与颅硬脑膜相比，脊髓硬脑膜中应力的非线性增加出现滞后。慢速数据拟合为单参数奥格登超弹性本构定律，在刚度G和名义上引入非线性的参数α方面观察到显著差异。进行了高达10%应变的高应变率应力松弛测试，并保持10秒。松弛过程拟合为四参数普龙级数指数衰减。颅硬脑膜和脊髓硬脑膜表现出相似的总体松弛，但在普龙级数参数上的松弛分布存在显著差异，这表明颅硬脑膜倾向于更快松弛。偏振光显微镜显示脊髓硬脑膜的结构实体沿轴向排列，而颅硬脑膜未表现出优先排列。用针对胶原蛋白和弹性蛋白的马松三色染色法和韦尔霍夫-范吉森染色法进行的定性确认也表明，脊髓硬脑膜中的弹性蛋白含量高于颅硬脑膜。
