Non-impact, blast-induced mild TBI and PTSD: concepts and caveats.

PRIMARY OBJECTIVE A volumetric blood surge (rapid physical movement/displacement of blood) is hypothesized to cause the non-impact, mild TBI and battlefield PTSD induced by a blast over-pressure wave. RESEARCH DESIGN Systematic review of the literature. METHODS AND PROCEDURES Articles relating to the fields of blast injury, brain injury and relevant disorders were searched between the years 1968-2010 for keywords such as 'brain injury', 'post-traumatic stress disorder' and 'blast pressure wave'. Articles found through journal and Internet databases were cross-referenced. MAIN OUTCOMES AND RESULTS The blood surge, which is driven by elevated overall pressure in the ventral body cavity after exposure of the torso to blast wave, may move through blood vessels to the low-pressure cranial cavity from the high-pressure ventral body cavity. It dramatically increases cerebral perfusion pressure and causes damage to both tiny cerebral blood vessels and the BBB. CONCLUSIONS Three factors may be critical to the induction of blast-induced brain injuries: (1) the difference in pressure between the ventral body cavity and cranial cavity; (2) blood that acts as a transmission medium to propagate a pressure wave to the brain; and (3) the vulnerability of cerebral blood vessels and the BBB to a sudden fluctuation in perfusion pressure.