MRI revealed reduced global and regional brain volume one year after mild traumatic brain injury (MTBI), according to a study published online March 12 in Radiology.
MTBI accounts for 85 percent of the estimated 1.5 million TBIs annually in the U.S. Studies show that 10 to 20 percent of MTBI patients continue to experience neurological and psychological symptoms more than one year following trauma. Brain atrophy has long been known to occur after moderate and severe head trauma, but less is known about the lasting effects of a single concussion.
Yongxia Zhou, PhD, from the department of radiology at New York University (NYU) School of Medicine in New York City, and colleagues enrolled 28 MTBI patients with posttraumatic symptoms after injury and 22 matched control subjects in the study. Nineteen of the 28 MTBI patients were followed for up to one year.
All participants underwent 3T MRI, neurocognitive testing and assessments for anxiety, depression and fatigue.
“The average BSI [boundary shift integral] in patients with MTBI from the time of initial assessment to one-year follow-up showed a loss of 7.6 cm3, larger than two times the changes seen in control subjects (3.7 cm3),” wrote Zhou and colleagues.
Patients with MTBI showed reduced gray matter (GM) and white matter (WM) volumes at one year. WM atrophy affected the anterior cingulate WM bilaterally and the congulate gyrus isthmus WM. GM atrophy affected the right precuneus. “These changes are greater than those we would normally expect to see after one year in a control population,” Zhou et al wrote.
The anterior cingulate has been implicated in mood disorders, including depression, and the precuneal region has many different connections to areas of the brain responsible for executive function. Changes in rostral anterior cingulate WM correlated significantly with scores on tests of verbal memory, learning and encoding as well as attention.
The study may be prone to selection bias due to follow-up focus on relatively more symptomatic individuals, according to the researchers.
"This study confirms what we have long suspected," Yvonne W. Lui, MD, neuroradiology section chief at NYU Langone School of Medicine, said in a press release. "After MTBI, there is true structural injury to the brain, even though we don't see much on routine clinical imaging. This means that patients who are symptomatic in the long-term after a concussion may have a biologic underpinning of their symptoms."