A critical review of experimental analyses performed on animals, post-mortem human subjects, and substitutes to explore primary blast-induced Traumatic Brain Injuries

Abstract

Although blast-induced Traumatic Brain Injury (bTBI) has become a signature wound of conflict, its cause is not yet fully understood. Regarding primary blast injuries, i.e., those caused by the propagation of shock waves in the body, four direct and two indirect injury mechanisms have been mainly proposed in the literature. Since numerous authors have exposed instrumented animals, Post-Mortem Human Subjects (PMHS), and head substitutes to blast conditions, the aim of this review is to classify them in terms of threat, instrumentation, and investigated mechanisms. In the first part, data are collected from 6 studies on PMHS, 1 on primates, 11 on rodents, and 6 on swine for comparison purposes. Peak amplitudes of reflected pressures, intracranial pressures and cranial strains are extracted and analyzed to establish trends. Despite the small number of comparable studies, several similarities can be highlighted. Indeed, the analyses revealed a dose-response effect for most measurements. The results also depend on the orientation of the subject (forward, backward, and sideways) for the PMHS, primates, and swine. The second goal of this review is to evaluate the behavior of substitutes developed to replace PMHS experiments. Shell strains and internal pressures are thus collected on 19 geometric and anthropomorphic substitutes to assess whether they faithfully represent a human head. The results showed that these substitutes are for the most part not properly designed and therefore cannot yet reliably replace PMHS experimental data.

Twenty Years of Blast-Induced Neurotrauma: Current State of Knowledge

“…Rather, it is a broad overview of the present state of knowledge in each subdomain. For a few subdomains, review articles 51 , 52 , 89 , 100 , 146 , 168 , 212 , 213 are already available in the literature. Nonetheless, we have extensively gone through the literature in each subdomain.…”

Design of a simplified cranial substitute with a modal behavior close to that of a human skull

“…Several metrics of interest were collected such as the time of wave arrival, the first peak values of the internal pressures and the shell strains, as well as the extreme values. Results showed that internal pressures and shell strains are related; however, only timedomain analyses were performed in those mentioned studies (Elster et al, 2023). Since the time history of quasi-ideal blast waves could be approximated by pulse signals with broad frequency spectra, it would be interesting to analyze blast related results in the frequency domain as well.…”