Mechanism of traumatic brain injury at distant locations after exposure to blast waves: Preliminary results from animal and phantom experiments

Purpose Primary blast-induced traumatic brain injury (bTBI) is the least understood of the four phases of blast injury. Distant injury induced by the blast wave, on the opposite side from the wave entry, is not well understood. This study investigated the mechanism of distant injury in bTBI. Materials and Methods Eight 8-week-old male Sprague-Dawley rats were divided into two groups: group 1 served as the control group and did not receive any shock wave (SW) exposure; group 2 was exposed to SWs (12.5 ± 2.5 MPa). Propagation of SWs within a brain phantom was evaluated by visualization, pressure measurement, and numerical simulation. Results Intracerebral hemorrhage near the ignition site and elongation of the distant nucleus were observed, despite no apparent damage between the two locations in the animal experiment. Visualization, pressure measurement, and numerical simulation indicated the presence of complex wave dynamics accompanying a sudden increase in pressure, followed by negative pressure in the phantom experiment. Conclusion A local increase in pressure above the threshold caused by interference of reflection and rarefaction waves in the vicinity of the brain-skull surface may cause distant injury in bTBI.