The signature wound of the conflicts in Iraq and Afghanistan is traumatic brain injury, which often involves injury from blast explosives. When a person is exposed to blast, he may not only endure a brain injury, but there is also a good chance that the body may also be injured from penetrating metal objects.
Metal that enters one part of the body can translocate over time to another part of the body. Typically, the blood-brain barrier (a web of brain cells that protect the brain from most substances) will prevent metal from being transported from one part of the body into the brain. However, when a brain has been injured, the blood-brain barrier is sometimes disrupted and weakened, allowing these foreign substances into the brain.
A recent animal study confirmed that a metal object from one part of the body can translocate into the brain after brain injury, further exacerbating the brain injury. Additionally, metal in the body can further weaken the blood-brain barrier over time. In the experiment, the translocation occurred within one month of the original injury. Co-occurring brain injury and injury to the body from penetrating metal should therefore be given special consideration.
Kallnich JF & Kasper CE. Do metals that translocate to the brain exacerbate traumatic brain injury? Medical Hypotheses. (May 2014).