Finite Element Modeling Approaches for Predicting Injury in an Experimental Model of Severe Diffuse Axonal Injury

Traumatic brain injury finite element analyses have evolved from crude geometric representations of the skull and brain system into sophisticated models which take into account distinct anatomical features. However, two distinct finite element modeling approaches have evolved to account for the relative motion that occurs between the skull and cerebral cortex during traumatic brain injury. The first and most common approach assumes that the relative motion can be estimated by representing the cerebrospinal fluid inside the subarachnoid space as a low shear modulus, virtually incompressible solid. The second approach assumes that the relative motion can be approximated by defining a frictional interface between the cerebral cortex and dura mater.

This study presents data from an experimental model of traumatic brain injury coupled with finite element analyses to evaluate the modeling approach's ability to predict specific forms of traumatic brain injury. Axial plane rotational accelerations produced prolonged traumatic coma in the miniature pig, axonal injury throughout regions of the white matter, and macroscopic hemorrhagic cortical contusions. Results from two-dimensional finite element analyses of the miniature pig showed that the manner in which the modeling approach accounts for the relative motions that occurs between the skull and cerebral cortex can dramatically influence the outcome of an analysis. Specifically, this study which compared the numerical response of two different finite element modeling approaches with animal injury data from four animal experiments, clearly demonstrated that the modeling approach which represented the relative motion between the skull and cerebral cortex as a frictional interface best predicted the resulting injury pattern in a fifth axial plane animal experiment.