Untangling the Effect of Head Acceleration on Brain Responses to Blast Waves

Abstract

Multiple injury-causing mechanisms, such as wave propagation, skull flexure, cavitation, and head acceleration, have been proposed to explain blast-induced traumatic brain injury (bTBI). An accurate, quantitative description of the individual contribution of each of these mechanisms may be necessary to develop preventive strategies against bTBI. However, to date, despite numerous experimental and computational studies of bTBI, this question remains elusive. In this study, using a two-dimensional (2D) rat head model, we quantified the contribution of head acceleration to the biomechanical response of brain tissues when exposed to blast waves in a shock tube. We compared brain pressure at the coup, middle, and contre-coup regions between a 2D rat head model capable of simulating all mechanisms (i.e., the all-effects model) and an acceleration-only model. From our simulations, we determined that head acceleration contributed 36-45% of the maximum brain pressure at the coup region, had a negligible effect on the pressure at the middle region, and was responsible for the low pressure at the contre-coup region. Our findings also demonstrate that the current practice of measuring rat brain pressures close to the center of the brain would record only two-thirds of the maximum pressure observed at the coup region. Therefore, to accurately capture the effects of acceleration in experiments, we recommend placing a pressure sensor near the coup region, especially when investigating the acceleration mechanism using different experimental setups.

Primary blast waves induced brain dynamics influenced by head orientations

“…Although the maximum reflected pressure occurred at the eye socket in the front-on case, the relatively small area interacted with the blast wave resulted in minimal ICP in this case. The computational work by Mao et al [17] demonstrated a similar trend in the rat brain, i.e., higher pressure for a lateral blast loading compared to a frontal one. However, the experimental work by Chavko et al [10] showed that rats experienced higher brain pressure in the frontal loading compared to that in the side-on one.…”

A 3-D Rat Brain Model for Blast-Wave Exposure: Effects of Brain Vasculature and Material Properties

“…We developed a 3-D FE model of a partial shock tube, similar to previous models,13,19,20 with a square cross-section of 0.20 m in width and 1.25 m in length (Fig. 1c).…”

Viscoelastic computational modeling of the human head‐neck system: Eigenfrequencies and time‐dependent analysis

“…In addition, extension to large deformations under visco‐hyperelastic constitutive laws, frequency dependent material properties, and multiscale approaches will then allow to investigate a wider range of frequencies, as well as the biomechanics of impact and traumatic brain injury phenomena, edema and deep subdural hematoma, and glioblastoma tumor growth . In this perspective, the high heterogeneity of the material model and the complexity of the geometry domain do not allow an easy prediction of the maximum displacement locations; however, the numerical study highlights measurable differences in the different regions.…”

“…In the last decades, advances in constitutive and computational tools of soft tissue biomechanicss allowed to address head bone conduction and its characteristic frequencies . Recently, advanced modeling tools have been specifically developed for skull sound‐wave measurement, head‐neck modal analysis, computational models for head injury validation, computer‐based atlas models, and brain biomechanical characterization …”