Why Is the Mystery of Blast Force Brain Injury So Tough to Solve?

"Healing Our Soldiers," the cover story of the February issue of National Geographic, is a searching inquiry into blast-induced traumatic brain injury—the signature injury suffered by American veterans of the Iraq and Afghanistan campaigns.

Known as shell shock in World War I, the devastating malady leaves victims with symptoms that range from sleep disorders to problems with memory and cognition. Many of the symptoms of blast-related brain trauma resemble those of post-traumatic stress disorder (PTSD), complicating diagnosis.

Though a definitive means of diagnosing and treating these injuries remains elusive, medical researchers are pursuing various theories about how blast force, particularly that caused by improvised explosive devices (IEDs), results in brain damage—in hopes of a breakthrough in understanding and, consequently, treatment.

Story author Caroline Alexander has just finished a 20-city radio tour that addressed issues raised by the article. From her home in New England, she explains her interest in the subject, responds to questions raised by the radio audience, and shares advice with veterans who worry that they may be suffering from the syndrome.

Tell us what inspired you to write about this subject in the first place.

From as far back as 2005, I was reading about and researching shell shock in World War I. This condition was originally believed to be the result of brain "commotion" caused by proximity to exploding shells—in other words, a physical injury.

But as the war progressed, it was remarked that many afflicted soldiers didn't appear to have been close to shells, nor were they visibly wounded. Shell shock was re-characterized as a "neurasthenic" condition, which is essentially a "nervous" condition.

I was steeped in research from this era when reports started coming out in the media about a problematic condition afflicting soldiers in Iraq. The symptoms were those of PTSD—but it seemed like something else was also going on and was somehow associated with exposure to IEDs.

I felt I was reading literature from a century before, and became very interested in this condition called TBI, or traumatic brain injury—the shell shock of our era.

By 2009, blast-induced TBI was starting to be understood as a distinct condition directly related to exposure to explosive force, and I felt it was time to jump in.

Now that the story has come out, what strikes you most about the reaction to it? TBI has been in the news a lot; are people aware of the condition?

What's most striking, even shocking, to me is the degree of confusion that still exists about so important a subject. You have to remember, blast-induced neurotrauma only came into focus around 2008-09.

That means that soldiers deployed in the early years of the campaign in Iraq generally weren't even aware they needed to keep track of the blast events they experienced. If you survived an IED attack and didn't appear to be injured, you didn't necessarily take it seriously. Symptoms appearing later weren't associated with a deployment that was long ago and far away.

I think of my brother-in-law. I wrote in the story that he took his life. He was an explosives expert and had sustained several IED attacks in Iraq. Ron was never diagnosed with TBI. None of us made a connection with blast force. Only in hindsight have I come to believe he was a combat casualty.

Did you find widespread concern among the soldiers and veterans you spoke with that, unwittingly, they might be candidates for diagnosis of blast-related brain injury?

In one radio interview, a caller asked if there was a safe standoff distance for exposure to blast. For example, ordnance handlers are instructed as to established safety thresholds, typically measured in pounds of pressure per square inch, or psi, unleashed by an explosion.

So exposure to five psi will rupture your eardrums, fifteen psi will damage your lungs, and so forth. The astonishing thing is that the brain isn't even mentioned on these conventional lists. So the caller was asking if I knew what pressure threshold was damaging to the brain—and I wondered if he was asking because he'd been exposed to blast. And the blunt truth is, no one knows.

We only know that it's a lot lower threshold than used to be imagined. There's a lot of evidence that repetitive exposure to relatively low-level blast is damaging—possibly lower than the five psi that damages eardrums. So I think that where there's so much un-clarity, there's got to be a certain degree of fear. The blast tests I described in the story are part of the effort to understand what might be safe.

What advice can you give veterans who are concerned they might have sustained blast injury? And what resources are available?

A broad range of symptoms is associated with blast-induced neurotrauma—sleeplessness, dizziness, memory problems, cognition problems, mood changes. And the first thing to note is there are many reasons you might have those symptoms, including extreme stress, PTSD—maybe even just transitioning back to civilian life.

The most diagnostic symptoms of blast-related TBI are persistent headaches, persistent ringing in the ears, and sensitivity to light. Those symptoms aren't typical of, say, PTSD, and if they're combined with a history of exposure to blast, they should be checked out.

Since much about blast-related TBI is unique to military experience—exposure to multiple blast events, for example—not all civilian doctors may be up to speed on the subject. I'd therefore suggest going to your VA center. These are generally well informed now—they'll know how to conduct an examination and advise.

Other resources for information include:

Defense and Veterans Brain Injury Center

Make The Connection: Shared experiences and support for Veterans

National Intrepid Center of Excellence

In the story you describe some promising medical advances, from diagnostic techniques to a better understanding of exactly how blast injures the brain. Can you give any updates?

There's so much we don't know about both blast and the brain. But very advanced, sophisticated types of brain scans have succeeded in locating abnormalities in the brains of living veterans diagnosed with blast-related TBI. The studies are small, but this is hugely promising.

There are also studies that examine brain function by tracking the brain's metabolism of glucose. And I think that it's possible that this year may see a breakthrough in understanding, at last, the mechanics of just how blast injures the brain. All this would put us on the path toward treatments.

Another point is that by subjecting veterans of the recent campaigns to such intense medical scrutiny, a great deal else has been discovered.

For instance, researchers at the VA Puget Sound in Washington State are investigating how factors of everyday life during deployment may be damaging: working in extreme heat in Iraq, extreme dehydration, extreme prolonged stress and hypervigilance, exposure to toxic fumes from burn pits, prolonged sleep deprivation. These all take a physical toll that's only starting to be measured.

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