Soldiers with traumatic brain injury caused by a blast may have abnormalities in the white matter of their brain — an important brain cell communication center — that cannot be seen on ordinary brain scans, U.S. researchers said Wednesday.
They said it is not yet clear whether the hidden injuries affect brain function or play a role in traumatic stress injuries.
Using an imaging technique called diffusion tensor imaging, researchers at Washington University of St. Louis studied 63 injured soldiers who had been evacuated to the Landstuhl Regional Medical Center in Germany from Iraq and Afghanistan after being exposed to different types of blasts.
They found abnormalities in 18 out 63 patients diagnosed with mild traumatic brain injury from blasts, but not among 21 control subjects who were injured in other ways.
The areas highlighted in the study have not been seen in other studies using the same imaging technology in civilians with brain injuries, suggesting there may be something different that occurs in blast injuries.
"This is the first (study) to offer evidence that there may be a unique consequence from the blast itself," Christine Mac Donald of Washington University, whose study appears in the New England Journal of Medicine, said in a telephone interview.
Mac Donald lived at the Landstuhl base for 5-1/2 months, working closely with military personnel there.
She said the abnormalities they found were in regions of the orbitofrontal cortex, an area involved in emotional regulation and reward-based behaviors, and the cerebellum, an area linked to coordination, movement, organization and planning.
Whether they suggest significant damage to the brain's white matter is not yet clear, nor is it clear if this damage alters important functions like attention, memory, emotional regulation, balance and coordination, Mac Donald said.
And the study did not show whether there is a link between these injuries and post-traumatic stress disorder.
"Our ongoing studies will hopefully start to answer some of these questions," she said in a statement.
Some 320,000 military personnel from wars in Iraq and Afghanistan have suffered traumatic brain injury, which are most often classified as mild brain injuries or concussions.
"We call these injuries 'mild', but in reality they sometimes can have serious consequences," Dr. David Brody of Washington University said in a statement.
Brody and Mac Donald say the findings need to be validated, but they hope the study might lead to new ways to diagnose changes in brain structure that may be occurring in patients with blast-related injuries.
"Our hope is that these advanced MRI-based methods will one day help make more accurate diagnoses, assist with triage and allow treatment interventions to start early for people with traumatic brain injuries," he said.