Investigation of blast-induced cerebrospinal fluid cavitation: Insights from a simplified head surrogate

Abstract

Blast induced traumatic brain injury (bTBI) has been a prevalent injury in recent conflicts. Post-mortem studies have shown damage in the brain tissue close to the cerebrospinal fluid (CSF) in bTBI cases compared to non-blast TBI cases. CSF cavitation is a potential mechanism for this brain/CSF interface injury. In this study, our aim was to explore the possibility and mechanism of blast induced CSF cavitation. We first developed a one-dimensional simplified human head surrogate and exposed it to nonlethal blast waves using a shock tube. High-speed videography and pressure sensors data showed the formation and collapse of cavitation in the CSF simulant. Then, we explored the mechanism of the cavitation using a finite element model of the head surrogate. We found that the pressure waves transmitting through the skull (outer wave) and tissue simulants (inner wave) are responsible for the generation and collapse of the cavitation bubbles, respectively. Next, we used this insight to explore the possibility of CSF cavitation in the human head using a detailed finite element model. The simulations verified the role of the inner and outer waves in the generation and collapse of cavitation. Our results suggested that CSF cavitation is likely to happen in the human head under blast loading. Finally, we studied the CSF cavitation in head surrogate models with different lengths. The results showed that the head length significantly affected the CSF cavitation, indicating the potential drawback of using small animals to study bTBI in human head. Our findings can improve our understanding of the brain/CSF interface injury after blast exposure and inform the design of protection systems and animal tests.