Heading Off Trauma

The U.S. Department of Defense estimates that over the past decade, nearly 200,000 U.S. service members affected by bomb blasts have experienced traumatic brain injury (TBI) ranging from concussion to long-term brain damage and death. Yet very little is known about how blast waves disrupt brain tissue.

To address that uncertainty, Raul ­Radovitzky, an associate professor of aeronautics and astronautics, is developing computer models to simulate explosions and their effects on the brain. He and his colleagues recently used the models to test the usefulness of adding a face shield made of transparent polycarbonate to the standard-issue helmet worn by most U.S. ground troops.

As the researchers reported in the Proceedings of the National Academy of Sciences, the models reveal that the shield could impede direct transmission of blast waves to the face, the main pathway through which waves from an explosion reach the brain.

The models are unprecedentedly precise in their ability to integrate the anatomical features of the head, such as the skull and sinuses, with the physical characteristics of stress waves transmitted by a blast. Radovitzky says researchers can also use the models to examine the effects of stress waves that originate from impacts other than explosions, such as football tackles or car accidents, making it easier to study TBI among civilians as well as soldiers. In an effort to encourage TBI-related research, Radovitzky has released the computer code used to create the models. (Request it by e-mailing tbi-modeling@mit.edu.)

“These are extremely unique and complex models that may have a huge impact on our ability to predict what type of protective gear to place on our warriors,” says Joseph Rosen, a professor of surgery at the Dartmouth-Hitchcock Medical Center, who chaired a Department of Defense science panel that analyzed the effects of blast injuries on wounded soldiers. While researchers can put instruments inside helmets to measure how blasts affect the helmets, “what is ultimately important is the impact of the blast on the face, skull, and brain,” he says.

Laurence Young, a professor of astronautics and of health sciences and technology, is leading another MIT effort to reduce TBI. He and his grad students are redesigning the foam liner inside military helmets to provide better protection from blast waves. Their research suggests that fluids such as glycerin, or granular materials like tiny glass beads, can be inserted into channels in the foam to deflect some of the blast energy. The group is currently running blast experiments at Purdue University to finalize a working prototype of its design.