Traumatic brain injury: An investigation into shearwaves interference effects

Abstract

Traumatic brain injury (TBI) is one of the leading causes of long-term disability in both industrialised and developing countries around the world. It results in impaired and structural damage to the brain, caused by the application of external mechanical forces to the head. This chapter aims to investigate the effect of shear wave interference as a key mechanism to TBI, by identifying localised regions of the brain exhibiting high strains in a comprehensive finite element (FE) head model. We improved a magnetic resonance imaging (MRI) voxel-based mesh model of the head by introducing key meningeal membranes (dura mater, falx cerebri and tentorium cerebelli). We used this model to identify regions of interest through modal analysis and investigate the shear wave interference mechanism by transient modal dynamic analysis (TMDA) and the traditional explicit direct integration method (EDIM) under frontal impact loading scenarios. TMDA is a novel procedure for 3D head models and allows investigation into the influence of individual deformation modes on the overall system response. Results show that falx cerebri and tentorium cerebelli play pivotal roles in the interference process, with some brain regions exhibiting amplification of strains 10-20 ms after impact. These strains are seen to be higher than those at the coup and counter-coup sites.