Brain images taken from hundreds of soldiers diagnosed with mild traumatic brain injuries suggest that methods for diagnosing concussions are inadequate in detecting damage. The results, part of the largest-ever imaging study of traumatic brain injury in the military, provide evidence that even brain injuries commonly classified as mild may lead to long-lasting damage.
Researchers at Walter Reed National Military Medical Center observed abnormalities in the white matter—the part of the brain responsible for transmitting signals between different regions—of more than half the participants, most of whom had been diagnosed with at least one concussion. Gerard Riedy, a neuroradiologist at Walter Reed who led the research, says the large number of abnormalities seen in this study was surprising, and it undermines the conventional wisdom that a person with mild traumatic brain injury should have normal brain images.
More than 300,000 U.S. service members have been diagnosed with traumatic brain injury since 2000, often the result of blast-related trauma. Using imaging to detect damage could help doctors determine the most appropriate treatment. Often in concussion cases neither a CT scan nor an MRI reveals any signs of brain damage. And the clinical tools available for assessing the injury, which include a patient’s history, evaluations of cognitive skills like memory and attention, and tests of certain motor skills, require a large degree of subjective interpretation, says Riedy. Further, those assessments can be muddled by other conditions like post-traumatic stress disorder, which can cause many of the same symptoms.
Riedy and his colleagues used an advanced form of MRI to look for abnormalities in the “wiring of the brain,” and they found them in nearly 52 percent of the more than 800 soldiers who participated in the study. The medical significance of the findings is not yet fully understood, but they are definitely abnormal, says Riedy. “Something has happened to that section of the brain, and the body has come in and tried to repair it, and it leaves a little scar.”
The group has also collected data from the same soldiers using other imaging techniques: one that can reveal disruptions in the way that white-matter fibers, or axons, are organized, and another that evaluates brain functionality by measuring blood flow to given regions. “We see abnormalities on those also,” says Riedy.