A Parametric Study of Age-Related Factors Affecting Intracranial Responses under Impact Loading Using a Human Head/Brain FE Model

The high frequency of fatal head injuries in elderly people in traffic accidents is one of the important issues in Japan. One of the causes may be vulnerability of the aged brain. While a human head/brain FE model is a useful tool to investigate head injury mechanism, there has not been such a model considering the structural and qualitative changes of the brain caused by aging. The objective of this study was to clarify the influence of intracranial changes on intracranial responses relating to brain injuries, which could be the basic knowledge to develop a head/brain model capable of representing injury mechanisms of the aged brain. The influence of eight factors representing structural and material features on intracranial response was parametrically studied using a human head/brain FE model. Furthermore, influence of the impact direction was studied swapping the axis in the model along which the acceleration pulses were applied. The following results were found: 1) PAC (Pia-Arachnoid Complex) layer volume and stiffness of bridging vein (BV) had a strong influence on elongation of BV, 2) stiffness of the brain strongly influenced dilatational damage measure (DDM) and 3) stiffness of the brain and PAC layer volume had a strong influence on cumulative strain damage measure (CSDM).