A mouse model of blast injury to brain: initial pathological, neuropathological, and behavioral characterization.

The increased use of explosives in recent wars has increased the number of veterans with blast injuries. Of particular interest is blast injury to the brain, and a key question is whether the primary overpressure wave of the blast is injurious or whether brain injury from blast is mostly due to secondary and tertiary effects. Using a shock tube generating shock waves comparable to open-field blast waves, we explored the effects of blast on parenchymatous organs of mice with emphasis on the brain. The main injuries in nonbrain organs were hemorrhages in the lung interstitium and alveolar spaces and hemorrhagic infarcts in liver, spleen, and kidney. Neuropathological and behavioral outcomes of blast were studied at mild blast intensity, that is, 68 ± 8 kPag (9.9 ± 1.2 psig) static pressure, 103 kPag (14.9 psig) total pressure and 183 ± 14 kPag (26.5 ± 2.1 psig) membrane rupture pressure. Under these conditions, we observed multifocal axonal injury, primarily in the cerebellum/brainstem, the corticospinal system, and the optic tract. We also found prolonged behavioral and motor abnormalities, including deficits in social recognition and spatial memory and in motor coordination. Shielding of the torso ameliorated axonal injury and behavioral deficits. These findings indicate that long CNS axon tracts are particularly vulnerable to the effects of blast, even at mild intensities that match the exposure of most veterans in recent wars. Prevention of some of these neurological effects by torso shielding may generate new ideas as to how to protect military and civilian populations in blast scenarios.