Blast Injuries and the Brain

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Blast Injuries and the Brain

A traumatic brain injury caused by an explosion or blast can be more complex compared with a TBI from other causes, like from a car crash or sports injury. In fact, explosive devices can produce multi-trauma injuries in an individual rarely seen outside combat.

According to the Defense and Veterans Brain Injury Center (DVBIC) more than 50 percent of injuries sustained during the conflicts in Iraq and Afghanistan are the result of explosives including bombs, grenades, land mines, mortar/artillery shells, and improvised explosive devices, or IEDs. Since 2006, blasts have been the most common cause of injury among American soldiers treated at Walter Reed Army Medical Center.

What is a blast wave?

A blast injury feels like being hit by a wave and then being pulled back into the ocean — all in intensely rapid succession (Jeffrey Barth, PhD). More scientifically, blast injuries result from the complex pressure wave generated by an explosion, an instantaneous rise in atmospheric pressure that is much higher than normal for humans to withstand. This is called a blast over-pressurization wave (CDC, Mass Casualties).

Mechanisms of blast injuries

There are four basic mechanisms of blast injuries. They are classified as primary, secondary, tertiary, and quarternary.

  • Primary blast injury is the explosion itself, which is an atmospheric pressure that hits the individual and pushes on all of the organs of the body. The blast over-pressurization wave, generated by the explosion, travels at a high velocity and is affected by the surrounding environment; for example, the effects of the blast wave may be increased in a closed environment such as a vehicle. Air-filled organs such as the ear, lung, and gastrointestinal tract as well as organs surrounded by fluid-filled cavities such as the brain and spinal cord are especially susceptible to primary blast injury (Elsayed, 1997; Mayorga, 1997). The over-pressurization wave dissipates quickly, causing the greatest risk of injury to those closest to the explosion.
  • Secondary blast injury is the result of energized fragments flying through the air; these fragments may cause penetrating brain injury.
  • Tertiary blast injury may occur when the individual is thrown from the blast into a solid object such as an adjacent wall or even a steering wheel. These types of injuries are associated with acceleration/deceleration forces and blunt force trauma to the brain similar to that observed following high-speed motor vehicle accidents.
  • Quaternary blast injury can occur in the presence of severe blast-related trauma resulting from significant blood loss associated with traumatic amputations or even from inhalation of toxic gases resulting from the explosion (DVBIC).

One or all of these mechanisms of blast injuries can occur simultaneously and can often cause multi-trauma injuries. Injuries can range from a brain injury and lung perforation to a lost limb or a contusion of the eye (CDC).

Symptoms

Difficulties experienced as a result of a brain blast injury can include a range of physical, emotional, cognitive, and behavioral symptoms. Many of these symptoms often occur along with other conditions such as depression or PTSD (DVBIC).

Research

The effects of blast injuries on the brain are still being studied; there is still a great deal to learn about the short- and long-term effects. In an effort to step up preventative measures, the military has implemented new policies such as screening all service members who have been at risk of a concussion — blast-related or not — and making mandatory a detailed evaluation for soldiers who have sustained three concussions before being released back to combat.

DVBIC, for one, has been involved in the validation of several important diagnostic tests for better identifying the blast effects on the brain. These include the use of advanced neuroimaging techniques, such as Diffuse Tensor-weighted Imaging (DTI) and advanced technologies for measuring the function of the brain as the individual works on specific tasks, a technique known as Magnetoencephalography (MEG) (DVBIC).

Proteins are also being studied as biomarkers that would allow combat medics at the point of injury to take a simple prick of the injured person’s finger with an instrument similar to that used by a diabetic to check blood sugar. If positive, the combat medic would know that the proteins associated with concussion or TBI were present in that person’s body. Having a simple blood test like this would be useful not only for the military but for civilians as well (Newsweek).

Sources

  • Barth, Jeffrey, PhD. Director, Brain Injury and Sports Concussion Institute, University of Virginia School of Medicine.
  • Bast, Andrew (November 7, 2010). ‘We Just Don’t Know,” Newsweek.
  • CDC Mass Casualties: Explosions and Blast Injuries: A Primer for Clinicians (2006).
  • Coupland, C. R. M., & Meddings, D. R. (1999). Mortality associated with use of weapons in armed conflicts, wartime atrocities, and civilian mass shootings: literature review. British Medical Journal, 319, 410-412.
  • Defense and Veterans Brain Injury Center website. http://dvbic.dcoe.mil/
  • Elsayed, N. M. (1997). Toxicology of blast overpressure. Toxicology, 121, 1-15.
  • Ippolitio, Charles J. (2007). Battlefield tbi: blast and aftermath. Applied Neurology, Vol. 3, No. 8.
  • Mayorga, M. A. (1997). The pathology of primary blast overpressure injury. Toxicology, 121, 17-28.
Posted on BrainLine December 13, 2010.

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Comments (3)

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I was a tank crewman in Nam, my first tour. We hit(what later was identified as probably a 175mm, unexploded Artillery Shell) a Mine and I was blown out of our tank turret. Another crewman told me later that I came out of the turret like a champagne cork, went up about 10’ and landed on the Armored back deck. I came down on the back of my head and neck, then my torso hit. I was in and out of consciousness and remember my eyes opening to see a ring of faces looking down at me and the Infantry medic leaned over and quietly told me to hold on, a stretcher was coming and I was going to be ok. Then I remember being on a stretcher, being handed down from my tank to guys on the ground. My next memory is being on the ground with my Infantry medic buddie and PltSgt. Salsman kneeling next to me and talking softly to me, but don’t remember what was said. I was dusted off to 93rd Evac, close to Saigon, maybe Bien Hoa. 93rd Evac medics put my Stretcher on a wheeled table and ran me into the hospital where I answered a Dr.’s questions, then wheeled into x-ray. I told them I was getting very nauseous and was given something to take. For the next four days I had an IV in each arm, still having dizzy spells and falling when I stood up and tried to walk. During my first exam the Dr. pressed right below my right side ribs and it hurt pretty bad and my final exam the pressure sensitive area still hurt!
Addendum: approx 30yrs later I was given a ratings exam by a VA Dr as he smoked a cigarette the entire exam. He pressed the sensitive area of my stomach, it still hurt and I told him what happened in Nam. He quickly let me know that that area couldn’t possibly be sensitive after so long, had to have been, or still was an ulcer. I told him that I’ve never had an ulcer, nor any symptoms of having one. He wrote there was nothing wrong with me, as a long cigarette ash fell off the cigarette, down the front of his white coat. As I took the paperwork he told me not to try that shit again, because he had written it up and would testify against me if I took it to court. I have never thought about litigation either then, or now. Don’t know what his problem was. I’ve started having dizzy spells and falling since 2004. I’m rated 100% with PTSD and died one time while I was in the hospital, but the Dr couldn’t tell me what caused me to die, then come back. This probably doesn’t make much sense, nor qualify for TBI treatment, but wanted to remind people about how the VA treated Nam vets from day one.

I was with the 1/92 Arty in the Central Highlands in '68-'69. The unit was in Vietnam from March 67 until October 71. During that time we fired 508,653 155mm howitzer rounds from a short-barreled M114A1 piece that had been brought back into service because it was the heaviest artillery piece that was transportable by air. Often our rate of fire would exceed 6 rounds per minute. The result of those multiple muzzle blasts is now being demonstrated in the declining brain function of many of our members. As a member of the S1 Section I experienced much less trauma than the firing batteries, but there was that one incident that most certainly caused the most damage: I was under a pair of 175s in a bunker on my first night in the unit when they cut loose at 2 AM. The concussive blast from the guns firing Zone 2 depressed me into the bunk and threw me up into the air, and on to the floor of the bunker as it rattled around in the bunker. As I was new in country, I expected to be a little disoriented the next day, but it seemed I was more so than usual. Throughout my tour I was exposed to more muzzle blasts, but none as powerful as that one. I was forward of the muzzles of the two pieces, and about 15' below them. My hearing was the first symptom I recognized, and has never recovered, but now I have numerous other conditions. My unit, as a whole, has been researching this injury, and I'm now in touch with US Senator Michael Bennet and his staff regarding having blast overpressure injuries declared battlefield injuries and compensated back to the time they occurred. At the time that first incident occured I believe I had a small stroke in the balance center of the brain - unusual in its location - and my brain in an MRI looks like its had white paint splattered all over it. Several of my mates have been diagnosed with brain tumors that the VA linked to blast overpressure, and cognitive decline in some is evident. Sure, we're all older now, and that happens, but to see a unified group such as ours slipping down the same slope simultaneously is more than a coincidence. SkyGunner, if you read this, please contact me via my private email - g.haydon@iaellc.com so that I can add your story to my evidence stack. The misdiagnosis of "shell shock", and the likely misdiagnosis of a multitude of cases of PTSD (many symptoms overlap with Post-Concussive Syndrome) needs to be addressed. We have been swept under the rug for too long, and I may finally have an opportunity to present this nationally. Your help would be much appreciated. There is a great Venn Diagram that shows the overlap and symptoms of both PTSD and PCS. I have few of the PTSD symptoms, and almost all of the PCS symptoms. PCS needs to be recognized and compensated.

It seems to me that a concussion changes a persons personality for a lifetime. If you take a radio and drop it so that the wires are crossed it will not be the same radio; even if you rewire it. When the brain cells reattach there are mistakes that are fundamental to a persons personality. When a cut on your arm heals there will be a scar as there will be on a brain. Brain concussions are the most insidious wound you can suffer because you can not become the same person when this happens. You yourself will not be able recognize the fact that you are different. It is my opinion that even the so called mild brain injury is damaging to one's personality traits.