On the clinical side, Ford studied 13 subjects who suffered mild TBI after IEDs exploded near them. Some were stunned, most lost consciousness at least briefly, and most cannot hold a job, he said.
The research partners hope to recruit more patients, especially military veterans, who were exposed to blasts that did not penetrate the skin and who suffered a loss of consciousness, Ford says. Candidates must have no other history of significant blunt traumas.
A battery of tests measured the subjects' memory, language and intelligence. These results were correlated with changes in functional magnetic resonance imaging (fMRI) from the patients. The 3-D fMRI studies can detect and map networks in the brain used for processes like movement, vision and attention. By comparing this data with those of a control group, Ford identified a subgroup of networks displaying abnormal brain activity in the patients. These results were then compared with energy deposition maps predicted by the computer simulations.
The research showed that certain regions of patients' brains are hyperactive, perhaps because they are compensating for adjacent, damaged areas of the brain that were hit with high energy from the blasts. The hyperactive regions are those that experienced the least shear and tensile energies, according to the computer simulations, which can be used to predict where the hyperactivity will likely occur, they say.
The studies also showed problems with how the patients used visual information, which corresponded to their complaints about having difficulty with attention spans, Ford said.
"This is our way to validate what the simulation shows with the clinical reality," he said.
Once Taylor and Ford determine exactly how and where the wave energy deposited in the brain gives rise to injuries, they can provide thresholds of stress and energy levels that cause TBI for consideration by helmet designers, Taylor said.
"I want us to be able to understand the physical mechanisms that lead to TBI. It would also be useful if we could make the connection between blast loading and blunt impact trauma," Taylor said. "Once we understand that we can be more comprehensive in how we protect both our warfighters and athletes against these sorts of injuries."
Source: DOE/Sandia National Laboratories