Saturday, July 23, 2011

Mechanisms of the special neurologic destruction caused by blast injuries

This is absolutely thrilling:
"Bioengineers identify the cellular mechanisms of traumatic brain injury; New hope for treatment of TBI in veterans wounded by explosions"

These scientists discovered the answers to two frustrating questions that have been blocking effective treatment of blast-related head injuries (TBI, or Traumatic Brain Injuries.)

1. What happens to the brain's axons? Why do the vital communication-arms of the brain's nerve cells just disappear?

2. Why does TBI from explosions cause the brain's blood vessels to shut down and turn themselves off, even though the the injury doesn't seem that bad?

The horrific health cost to our soldiers on active duty has included being blasted by explosives. These cause profound and persistent brain injuries that seem too severe for the amount of shock experienced by the brain.

1. The axons are part of an interlocked structure that's woven together by cells and intracellular "glues." This structure is shaken apart by explosive shock. Axons have to release their connections and shrink, retreating into the body of the cell. This destroys the physical functional structure of the brain. The person instantly loses memories and processing power, as well as a pervasive host of brain tasks.

2. The vessels undergo a mechanical stretch caused by the explosive force pushing through the gelatinous mass of the brain, and then, as a result of that stretch, they become super-sensitive to the chemical messenger that tells them to snap shut and then stop acting like vessels at all.
Normally, #2 only happens in the case of severe hemorrhagic (that is, bleeding) stroke. However, we now know that it also happens in blast injuries that otherwise cause less apparent damage.
Clinical note: Blast injuries to the brain are uniquely insidious. They cause diffuse injury that's invisibly disabling and incredibly hard to manage, let alone recover from significantly. Behavioral issues and so forth are mechanically and chemically imposed on the soldier's brain; they are not wilful choices on the soldier's part.

A lot of fundamental retraining has to be done, because emotional, cognitive and social skills have to be significantly rebuilt and rewired. The wiring that the soldier has built on since childhood has been torn up on duty.

Thanks to our present understanding of neuroplasticity, there's hope and a path to develop, but it takes time. On top of psychological trauma and the damage that causes to the amygdala and sometimes the hippocampus, it's a hell of a lot for any layperson to grasp, let alone try to handle.

One of the truly thrilling things about these findings is the discovery of a process that keeps the axons from pulling back in the first place. At present, it works in a Petrie dish if given within 10 minutes of injury; hard to see how that could work in combat.

If it could be formulated to be used in a person, it would still have to be administered extremely fast. Maybe send each soldier out with an inhaler of the stuff? Or a nose spray? A 50-cent bottle apiece to save millions in treatment, lost wages, cost of care, incidental costs on the family, for each injured soldier. Seems like a bargain!

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