A sophisticated imaging technique has revealed signs of brain injury in soldiers injured in explosions. The injuries, which don’t show up with standard imaging techniques, may help explain why some soldiers suffer long-term problems after such injuries.
Brain injuries caused by blasts from improvised explosive devices, rocket-propellant grenades, or land mines in Iraq and Afghanistan are a major concern for the U.S. military. An estimated 10 to 20 percent of all deployed troops have experienced mild traumatic brain injuries as a result of such blasts. And although these injuries are linked to long-term psychological and mental problems, medical experts lack the means to detect any resulting physical damage.
A study by researchers at the Washington University School of Medicine in St. Louis and the U.S. military found that damage to the brain can be detected using an advanced form of magnetic resonance imaging (MRI) called diffusion tensor imaging (DTI). This technique tracks the movement of water molecules through the brain, providing a detailed picture of the brain’s white matter—the neural wiring that connects cells. Damage to this tissue has long been associated with mild traumatic brain injury.
The researchers studied 63 soldiers who were diagnosed with traumatic brain injury after being injured in explosions in Iraq and Afghanistan. The diagnosis was based on such symptoms as loss of consciousness, confusion, and headaches. Standard imaging methods, including MRI and CT, did not show any brain injury in most cases. The researchers studied the soldiers within 90 days of admission to the Landstuhl Regional Medical Center in Germany, and again six to 12 months later.
In the study, conducted from 2008 to 2009 and published June 2 in the New England Journal of Medicine, the researchers found that 18 of the 63 subjects diagnosed with traumatic brain injury had abnormalities in the white matter in two or more regions of the brain. A further 20 subjects had abnormalities in one area, and 25 had none. The abnormalities were also consistent with computer simulations of the likely effect of explosions on the brain.
“The significance of the new study is that it contains data across time,” says David Moore, a professor of neurology at Tulane University School of Medicine in Louisiana and the former deputy director of the Defense and Veterans Brain Injury Center in Washington, D.C. “A year later, the DTI findings showed there were still abnormalities in the brain’s white matter, suggesting that this type of injury can have long-lasting effects.”