WAR'S NEW WOUNDS
A Shock Wave of Brain Injuries
"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.