Delayed Brain Damage
Blast Injuries and veteran brain damage is gaining attention as the war in Iraq continues. Here is an article that addresses how the brain is injured in explosion events and how the brain may actually become increasing damaged as the trauma continues.
Blasts cause delayed brain trauma
Improvised explosive devices have killed at least 1,600 soldiers in Iraq since the United States invaded in 2003. Thanks to high-tech body armor, new helmets, and better resuscitation techniques, many more soldiers now survive blasts. But this has revealed a new problem: Blast exposure, especially repeated exposure, can cause brain damage so subtle that soldiers may not realize they've been wounded. Ibolja Cernak, director of the Biomedicine Business Area at the Applied Physics Laboratory, says that these mild brain injuries can lead to gradual neurodegeneration, similar to Alzheimer's disease.
Most experts acknowledge that explosions can injure the brain even when there is no direct blow to the head. The prevailing argument has been that waves of compressed air emanating from the blast shake the skull with enough force to strain or stretch the brain, not unlike what happens in a bad car crash. "It's like a turbo-charged whiplash," says Ross Bullock, a professor in the Department of Neurological Surgery at the University of Miami.
But Cernak's research suggests a different mechanism. She posits that energy from the explosion compresses the abdomen and chest, generating oscillating waves in large blood vessels such as the aorta. These waves, she says, then carry that energy, at the speed of sound in water, to the brain, where it induces slight physiological changes in brain structures — for instance, slowing a cell's metabolism or altering the permeability of its membrane — that can lead to delayed neuronal cell death. The effects can cascade over time. Symptoms such as balance problems and impaired speech may manifest months or years after the blast. Cernak calls this syndrome blast-induced neuro-trauma (BINT).
"If what she's saying is true," says Jeff Bazarian, a brain injury expert at the University of Rochester Medical Center in New York, "then how the brain gets injured by a blast is very different than how it gets injured in a car accident." Not everyone is convinced that Cernak is right, but if she is, her hypothesis has implications for body armor design. Armor currently used in the field contains hard plates that could, according to Cernak's hypothesis, concentrate the power of a blast and make neurological damage worse.
Cernak began her career at the Military Medical Academy in Belgrade. During the fighting that followed the collapse of Yugoslavia in the late 1980s, she was one of the first to study the neurological effects of blast injuries, sometimes collecting blood samples on the battlefield minutes after an explosion. Today most of her research takes place in the lab, where she replicates blast pressure waves using a shock tube, and studies their effect on rodents.
"I've been fighting since 1990 with the military medical community to convince them that BINT exists," Cernak says. "It is still a fight, but finally this problem is getting acknowledged." —Cassandra Willyard, A&S '07 (MA)
