To meet the need for relevant regional central nervous system (CNS) tissue properties, the authors measured the material response of two regions of the CNS: the brainstem and the cerebrum. Specifically, adult porcine tissue was subjected to high loading rate mechanical deformation using a custom designed oscillatory shear device. Complex shear moduli were calculated over a range of frequencies (20-200 Hz) at two engineering strain amplitudes (2.5%, and 5.0%). For 2.5% strain, the magnitude of the storage modulus was significantly greater (about 20%) for the brainstem than the cerebrum, while the loss modulus showed no regional dependence. As a result, the complex modulus, G, showed no statistical difference between regions for 2.5% strain. For 5.0% strain, both components of the complex modulus of the brainstem were greater than those of the cerebrum (about 80%). At this strain, the regional difference in G was statistically evident. The modulus calculations at the higher strain magnitude should be incorporated into current anatomically detailed finite element models (FEM's). These region-specific differences provide essential information for enhancing the understanding of traumatic brain injury mechanisms. (A)
Samenvatting