How do explosive blasts cause a TBI?
- Blasts from various forms of improvised explosive devices (IEDs) are a common cause of combat-related injury in the military and were the most common cause of combat-related concussions during Operation Enduring Freedom and Operation Iraqi Freedom
- There are four different mechanisms through which a blast can cause injury:
- Primary injury: Atmospheric over-pressure followed by under-pressure or vacuum
- Secondary injury: Objects placed in motion (shrapnel) by the blast hitting the service member
- Tertiary injury: Service member being thrown by the blast and hitting their head against the ground, a wall, or other solid surface
- Quaternary injury: Other injuries from the blast such as burns and crush injuries
- For passengers in vehicles hit by a blast, such as an IED, it’s common to sustain both a primary and tertiary injury
Does a blast cause different brain injuries than blunt trauma?
- There currently is no evidence to suggest significant differences between blast and blunt injury:
- MRI imaging studies, such as diffusion tensor imaging, don’t indicate microstructural differences
- No cognitive differences have been identified between blunt and blast induced concussions
How should TBI from a blast injury be treated?
- Since most evidence suggests that blast and blunt TBI are very similar, there’s no difference in the treatment
- All service members who sustain a concussion following a blast are thought to have injury not only from the blast, but also from blunt trauma