A Shock Wave of Brain Injuries

By Ronald Glasser
Sunday, April 8, 2007

"We can save you. But you might not be what you were."

Neurosurgeon, Combat Support Hospital, Balad, Iraq

This is the new physics of war. Three 155mm shells, linked together and combined with 100 pounds of Semtex plastic explosive, covered by canisters of butane or barrels of gasoline, can upend a 70-ton tank, destroy a Humvee or blow an engine block through the hood of a truck. Those deadly ingredients form the signature weapon of the war in Iraq: improvised explosive devices, known by anybody who watches the news as IEDs.

Some of the impact of these roadside bombs is brutally clear: Troops are maimed by projectiles, poisoned by clouds of bacteria-laced debris and burned by post-blast flames. But the IEDs have added a new dimension to battlefield injuries: wounds and even deaths among troops who have no external signs of trauma but whose brains have been severely damaged. Iraq has brought back one of the worst afflictions of World War I trench warfare: shell shock. The brain of a soldier exposed to a roadside bomb is shocked, truly.

About 1,800 U.S. troops, according to the Department of Veterans Affairs, are now suffering from traumatic brain injuries (TBIs) caused by penetrating wounds. But neurologists worry that hundreds of thousands more -- at least 30 percent of the troops who've engaged in active combat for four months or longer in Iraq and Afghanistan -- are at risk of potentially disabling neurological disorders from the blast waves of IEDs and mortars, all without suffering a scratch.

For the first time, the U.S. military is treating more head injuries than chest or abdominal wounds, and it is ill-equipped to do so. According to a July 2005 estimate from Walter Reed Army Medical Center, two-thirds of all soldiers wounded in Iraq who don't immediately return to duty have traumatic brain injuries.

Here's why IEDS carry such hidden danger. The detonation of any powerful explosive generates a blast wave of high pressure that spreads out at 1,600 feet per second from the point of explosion and travels hundreds of yards. The lethal blast wave is a two-part assault that rattles the brain against the skull. The initial shock wave of very high pressure is followed closely by the "secondary wind": a huge volume of displaced air flooding back into the area, again under high pressure. No helmet or armor can defend against such a massive wave front.

It is these sudden and extreme differences in pressures -- routinely 1,000 times greater than atmospheric pressure -- that lead to significant neurological injury. Blast waves cause severe concussions, resulting in loss of consciousness and obvious neurological deficits such as blindness, deafness and mental retardation. Blast waves causing TBIs can leave a 19-year-old private who could easily run a six-minute mile unable to stand or even to think.

Another problem is that these blast-related brain injuries differ from other severe head traumas, and the complexity of treating returning troops with "closed-head" injuries is taxing an already overburdened military health-care system. There is not a neurosurgeon who works in a trauma unit anywhere in the United States who doesn't know what to do when an ambulance brings in a biker who has suffered a severe head injury in a highway accident. The standard care involves using calcium channel blockers to protect damaged nerve cells against further injury, intravenous diuretics to control brain swelling and, if the swelling becomes too great, removal of the top of the skull to allow the brain to swell without increasing neurological damage. This is what surgeons did in the case of ABC News anchor Bob Woodruff, who suffered severe brain injuries from an IED blast in Baghdad last year.

All this works with the common types of severe head injuries, but it does not work with brains damaged by shock waves. Despite the usual interventions and treatments, the majority of blast-injury patients who have neurological damage do not fully recover. There is a growing understanding within the neurosurgical community that blast injuries are different from those caused by penetrating or skull-fracture trauma. It is thought that shock waves damage the brain at a microscopic, sub-cellular level. That's why surgeons who are quite capable of reconstructing the skull of a motorcycle crash victim -- something for which they have been well trained -- struggle to come up with treatment and rehabilitation techniques for the explosion-damaged brains of troops.

"TBIs from Iraq are different," said P. Steven Macedo, a neurologist and former doctor at the Veterans Administration. Concussions from motorcycle accidents injure the brain by stretching or tearing it, he noted. But in Iraq, something else is going on. "When the sound wave moves through the brain, it seems to cause little gas bubbles to form," he said. "When they pop, it leaves a cavity. So you are littering people's brains with these little holes."

Almost as daunting as treating TBI is the volume of such injuries coming out of Iraq. Macedo cited the estimates, gleaned at seminars with VA doctors, that as many as one-third of all combat forces are at risk of TBI. Military physicians have learned that significant neurological injuries should be suspected in any troops exposed to a blast, even if they were far from the explosion. Indeed, soldiers walking away from IED blasts have discovered that they often suffer from memory loss, short attention spans, muddled reasoning, headaches, confusion, anxiety, depression and irritability.

What's baffling is the Pentagon's failure to work with Congress to provide a steady stream of funding for research on TBIs. Meanwhile, the high-profile firings of top commanders at Walter Reed have shed light on the woefully inadequate treatment for troops. In these circumstances, soldiers face a struggle to get the long-term rehabilitation necessary for a TBI. At Walter Reed, Macedo said, doctors have chosen to medicate most TBI patients, even though cognitive rehabilitation, including brain teasers and memory exercises, seems to hold the most promise for dealing with the disorder.

Oddly enough, having more military patients than can be adequately treated is, in terms of warfare, a gruesome kind of success. These are the war injured who once would have been the war dead. And it is the unexpected number of casualties who in a previous medical era would have been fatalities that has sunk the outpatient clinics at Walter Reed and left those in the VA system lost and adrift.

In Iraq and Afghanistan, the ratio of wounded service members to fatalities is 16 to 1, if the definition of "wounded" is anyone evacuated from a combat zone. During the Vietnam War, according to the VA, the ratio was 2.6 to 1. U.S. troops no longer die from the kind of injuries that killed many thousands in Vietnam. The majority of combat deaths there occurred right where the soldier was hit. If you were going to die, you were dead before there was any need of a medevac chopper. If you'd had an arm or leg blown off, the chances were that you had also suffered a penetrating chest or abdominal wound and would bleed to death waiting to be taken to the nearest surgical hospital.

But if the bleeding could be staunched and you were still breathing when the medics got to you, the odds on survival were in your favor. The military medicine practiced in Vietnam wasn't so different from what World War II medics practiced: Stop the bleeding and hope for the best until the helicopter shows up.

It wasn't until October 1993, when a U.S. combat assault team rappelled down from a helicopter into a 72-hour gunfight in the streets of Mogadishu, Somalia, that the notion of military medicine changed from basic life support to intensive care. In that siege situation, medics had no choice but to care for a growing number of wounded on their own, because evacuation was impossible. But without clear intensive-care procedures, they ran out of medications and fluids to treat the most severely injured.

In the civilian world, trauma medicine had progressed throughout the 1970s and '80s, well past the simple expedients of tourniquet, plasma and keeping an airway open. Mogadishu forced the military to abandon the last of its medical practices from Vietnam. It was time to teach the medics a new trade.

Pentagon officials increased the training period for a 91W, or combat medic, from 10 to 16 weeks. Medics now trained on patient simulators that would "bleed to death" if blood loss was not stopped or "suffocate" if chest tubes weren't correctly placed or a tracheotomy wasn't performed within three minutes. Medics learned the new intensive-care theory of "hypotensive resuscitation," in which intravenous fluids are given only in minimal amounts solely to keep the heart pumping, as opposed to the old Vietnam method of keeping blood pressure elevated, which only added to blood loss. Medics today use better-designed tourniquets and hemostatic bandages -- dressings that act to stop bleeding for better hemorrhage control. They administer the latest non-opiate painkillers, which, unlike morphine and Demerol, do not slow breathing. This is the first war in which troops are very unlikely to die if they're still alive when a medic arrives.

Another large part of the 16-to-1 wounded-to-fatality ratio has to do with advances in body armor. Today's body armor is dramatically effective in preventing fatal wounds of the chest and upper abdomen. There is not an orthopedic or general surgeon in Iraq or Afghanistan who hasn't been astonished the first time a trooper with two missing limbs and a traumatic brain injury is carried off in a chopper and the surgeon removing the armor cannot find a scratch from the chin to the groin.

But the unseen damage can be long-lasting. Most of the families of our wounded that I have interviewed months, if not years, after the injury say the same thing: "Someone should have told us that with these closed-head injuries, things would not really get all that much better."

Now in its fifth year, the Iraq conflict is not a war of death for U.S. troops nearly so much as it is a war of disabilities. The symbol of this battle is not the cemetery but the orthopedic ward and the neurosurgical unit. The men and women inside those units have come home alive but missing arms and legs, many unable to see or hear or remember who they were before being hit by a roadside bomb. Survival clearly represents as much of a revolution in military medicine as does the dominance of the suicide bomber and the roadside bomb in the age of "shock and awe." But now both the medical profession and the country are left to play a terrible game of catch-up.

Ronald Glasser is a pediatric nephrologist and the author of " Wounded: Vietnam to Iraq," published last year. From 1968 to 1970, he was deployed at the U.S. Army Hospital at Camp Zama, Japan, treating U.S. soldiers wounded in Vietnam.

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