Deciphering Today’s Signature War Injury

Science Progress

December 2, 2008 – The wars in Iraq and Afghanistan brought the American military some unpleasant surprises, prominent among them the vicious effectiveness of cheap, small armaments such as mines, roadside bombs, and rocket-propelled grenades. But the soldiers, commanders, and strategists in Iraq and Afghanistan are not the only ones struggling to adapt.

Across the nation, in hospitals, clinics, and doctor’s offices both military and civilian, health care providers are facing unprecedented challenges in dealing with these weapons’ results. Among the most puzzling is a set of injuries widely considered a medical “signature” of this conflict, and one that raises clinical and scientific questions thus far unanswered.

This is the combination of traumatic brain injury and post-traumatic stress disorder. TBI is a force to the head that damages the brain and impairs its function, with the extent and kind of harm depending on the exact location and scope of the injury. PTSD is a terrifying and often disabling anxiety disorder caused by the experience of violent trauma.

Any blast powerful enough to cause TBI is also powerful enough to cause PTSD, so a high—though unknown—percentage of the many exposed to blasts suffer from both. The scientific literature finds that “anywhere form 20% to 60%” of blast victims have PTSD, says Maxine Krengel, PhD, clinical neuropsychologist at the Department of Veterans Affairs Poly Trauma Network Site in Boston. “It’s huge.” The circumstances of the “event itself” indicate TBI, Krengel says. For example, “did the somebody have a loss of consciousness? If so, for how long?” At least mild TBI is therefore also very common.
Many Questions

A major clinical challenge is that the symptoms of the two conditions overlap—although the conditions are very different in their natures—making diagnosis often “very, very tricky,” Krengel says. TBI causes physiological damage to brain tissue that can result in cognitive deficits and reduced emotional control, among many other problems. PTSD is a learned connection between a traumatic event and a set of responses, which can include nightmares, flashbacks, and constant anxiety and can lead sufferers to alcohol, drugs, and even suicide. But the two conditions share many markers, including sleep disruption, irritability, personality changes, difficulty concentrating and remembering, depression, and more.

To add to the complication, the presence of one condition can interfere with the treatment of the other. And to make things even more uncertain, the type and extent of the brain damage caused by the compression wave of a blast appears to differ considerably from the injuries that form the basis of current scientific understanding of TBI.

“Most of the TBI research has been done in survivors of either motor vehicle accidents or sports injuries—a quarterback [who] gets knocked unconscious” or a driver who hits his head against the steering wheel, says Matthew Friedman, MD, PhD, Executive Director of the National Center on PTSD and professor of psychiatry at Dartmouth medical school. “But the real question that a lot of people are raising is, given the tremendous impact of an explosion, can it really compare to the impact of even a 350 pound defensive end knocking you to the ground? Even though that’s pretty bad, is it anything to compare to a bomb blowing up your Humvee and killing the person sitting beside you?”

Beyond a difference in strength of the impact, Krengel adds, the percussive wave of an explosion acts differently on tissue than an ordinary blow. “The blast impacts the air-filled cavities in the body, every air-filled cavity,” she says. “It’s different in different areas and also depending on how close you are to the blast.”

What is known about the impact of blasts on the brain essentially comes from animal models. “But in the animal literature there is a difference in what the connectivity looks like”—in other words, how the brain’s parts work together—”in blast injury versus traumatic brain injury, that we are typically used to seeing,” Krengel says.

“And then the second piece is that so many of these people have had more than one blast injury,” Friedman continues. So the crucial but as yet unresolved scientific question, he says, is “How generalizable is the sports injury or motor vehicle accident to what is coming into Walter Reed or VA hospitals these days?”
Figuring Out How to Help

The point is not just to study the problems with more science, but to find the best ways of helping suffering human beings, Friedman and Krengel emphasize. “We have two fabulous treatments for PTSD,” says Friedman. “These are evidence-based treatments and…vigorous review recently by the Institute of Medicine has verified their effectiveness.” One treatment, cognitive behavioral therapy, uses systematic, Socratic challenges to thinking about the traumatic experience to help patients restructure their thinking. The other, exposure therapy, breaks the Pavlovian connection between the event and the response with guided confrontation with the troubling memories. Beyond that, several medications help control the symptoms, though they do not resolve the basic issues. If medication is used alone, the symptoms return when treatment ends. Successful psychotherapy, however, permanently frees people from the terrors of PTSD. Which type of psychotherapy works better in a given case depends on the individual, but, Friedman says, in tests of otherwise normal individuals, both overall “perform extremely well and equally well.”

There are no drugs approved for TBI, although some appear to provide some benefit. They are not, however, the same drugs useful for PTSD.

But blast victims very often also have some degree of TBI, and depending where and how it damaged the brain, TBI can reduce the effectiveness of either or both of the two best PTSD treatments. Cognitive damage can impair the intellectual resources needed for cognitive behavioral therapy. The loss of emotional inhibition caused by brain injury can make a person unable to tolerate the emotional stress involved in exposure therapy. Mild TBI very often resolves over time, potentially allowing psychotherapy to work, but clinicians do not consider waiting a sound option because, as Friedman says, “six months is a long time to suffer.”

An additional potential complication is that a damaged brain may not tolerate medications very well. There are no drugs approved for TBI, although some appear to provide some benefit. They are not, however, the same drugs useful for PTSD.

A number of studies and proposals are underway, many of them sponsored by the VA or the Department of Defense, Krengel says, noting that, “The VA system is developing treatment modules or manuals to treat the pain issues, the PTSD, the depression.” Whether sufficient resources have been devoted to studying these conditions is a matter of opinion. But, Friedman notes, “It’s probably going to be a few years until we have definitive data. What I can tell you is that we understand the challenge and research is ongoing.”

Until the big questions get answered, “the challenge is to figure out what to do for these folks. We have some good stuff on PTSD, other [work] on TBI. The question is how applicable, how useful is it going to be for this more complicated situation. Can we utilize what works in the less-complicated cases and how much are we going to have to improvise?” At present, clinicians are improvising ad hoc modifications to treatments to make them more usable by individuals with impairments, while waiting for research to provide more answers.
Is It Enough?

Beyond these questions of basic knowledge and treatment are large issues of access to appropriate care. Although the VA maintains a number of specialized polytrauma centers in various parts of the country for dealing with complicated cases, for an unknown but undoubtedly large number of veterans distances can be large and waiting times long. People with mild TBI and PTSD can be “quite ambulatory and they’re going to walk into primary care clinics, psychiatric clinics” throughout the nation, Friedman says. They often show up with vague symptoms such as headaches or sleep disturbances. Many providers lack even the understanding of the conditions found in more specialized facilities. That’s why, he says, primary care doctors and mental health providers across the country need to be educated about these conditions and told that “anyone who has been in uniform should be asked about the different kinds of exposures they’ve had.”

For now, though, untold numbers of service members and veterans who have experienced blasts are suffering, often without knowing why. And PTSD can strike months or years after a traumatic experience. “You might be in a blast and you have to immediately go back to your job,” Krengel says. “You can sort of keep it together while you’re busy, busy, busy, but after you’re home for a while, people say, ‘Wait, I’m not functioning the way I should be.'”

The experience of a blast may therefore be a time bomb that goes off long after the traumatic event. Unless and until researchers and clinicians answer the crucial questions and effective care is readily available from military, veteran, and civilian providers, it should surprise no one that many who served in today’s wars continue to feel their effects long after the conflicts end.

Washington, D.C. science journalist Beryl Lieff Benderly contributes the monthly “Taken for Granted” column on labor force and early career issues to the website of Science magazine and articles to other major magazines and websites.

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