In most cases, traditional MRI scans of people who sustain a concussion look like normal, healthy brains – something that puzzles the medical profession.
Now a new study, co-authored by a Brigham Young University professor, shows where there may be a problem. Using a different technique for analyzing MRI scans, the researchers captured images indicating apparent swelling in the networks connecting the two sides of the brain. The finding provides brain researchers with specific direction in their efforts to understand what happens to the estimated 1.4 million people in the United States each year who sustain a brain injury.
The study, which appears in the March 18 issue of the journal Neurology, is co-authored by BYU psychology professor Erin Bigler and colleagues at Baylor College of Medicine. The lead author, Baylor professor Elisabeth Wilde, is a former BYU student who worked in Bigler’s lab.
“Most concussions are relatively benign and most people recover – and recover quickly – but not all do,” said Bigler. “In this case we now have a technology telling us that something isn’t right in this part of the brain at least in the first few days following a head injury. We need now to have long-term studies see if this relates to any lasting problems.”
Recent studies have linked multiple concussions to higher risk of memory loss and other conditions, such as depression. Some of the leading causes of concussions are automobile accidents and sports injuries, making them a major concern for teenagers. According to the Centers for Disease Control, the two most at-risk age groups are children 0 to 4 years old and teenagers 15 to 19 years old.
Concussion is also the number one neurological injury in soldiers in Iraq and Afghanistan.
In Bigler and Wilde’s study, the researchers analyzed scans of 10 teenagers who had sustained a concussion between one and six days prior. A control group of 10 uninjured teens of similar age and gender distribution was also analyzed.
As expected, traditional MRI imaging did not detect any differences between the two groups. The researchers then applied a second technique called “diffusion tensor imaging,” or DTI, which establishes the direction of water flow through the fiber tracts that connect the two halves of the brain, a region called the corpus callosum.
This technique revealed differences in how the corpus callosum appeared for the injured group compared to the uninjured control group. The researchers believe these findings are evidence of injury to the corpus callosum, suggesting that the concussions had caused edema or swelling in these fiber tracts, disrupting their normal ability to transmit messages in the brain.
The researchers also looked at severity of concussion symptoms, such as persistent headaches, having trouble concentrating or remembering things, and feeling sad, tired or irritable. Their analysis found that the patients with the worst symptoms showed the most substantial differences in the images.
“These MRI findings related to the symptoms they experienced, which takes us an important step further in understanding how concussions disrupt normal brain function and how injury to the corpus callosum may participate in this,” Bigler said.
In a previous study, the researchers found similar evidence of injury to the corpus callosum by applying the technique to scans of children who had sustained more serious brain trauma.
To describe what happens in the brain when the head is struck, Bigler holds his two fists together to represent the two halves of the brain, which are connected across the middle by the corpus callosum.
“A blow to the head causes movements that place stresses and strains on the fiber tracts between the two halves of the brain that make up the corpus callosum, disrupting the physical and functional connections between the two halves,” Bigler said.
Bigler and his collaborators plan a number of follow-up studies, such as looking at how the brain recovers when a concussion causes these detectable differences in the corpus callosum. They also plan to look at many other brain regions to see if concussions affect other areas in addition to the corpus callosum.
Writer: David Luker