Brain compensates after traumatic injury, evidence shows

"This finding could lead to strategies for preventing and repairing the damage that accompanies traumatic brain injury," said Michael Lipton, M.D., Ph.D., who led the study and is associate director of the Gruss Magnetic Resonance Research Center at Einstein and medical director of MRI services at Montefiore, the University Hospital and academic medical center for Einstein.

Each year, 1.7 million people in the U.S., sustain traumatic brain injuries (TBI), according to the Centers for Disease Control and Prevention. Concussions and other mild TBIs (or mTBIs) account for at least 75 percent of these injuries. Following a concussion, some patients experience a brief loss of consciousness. Other symptoms include headache, dizziness, memory loss, attention deficit, depression and anxiety. Some of these conditions may persist for months or even years in as many as 30 percent of patients.

The Einstein study involved 17 patients brought to the emergency department at Montefiore and Jacobi Medical Centers and diagnosed with mTBI. Within two weeks of their injuries, the patients underwent diffusion tensor imaging (DTI), which "sees" the movement of water molecules within and along axons, the nerve fibers that constitute the brain's white matter. DTI allows researchers to measure the uniformity of water movement (called fractional anisotropy or FA) throughout the brain. Areas of low FA indicate axonal injury while areas of abnormally high FA indicate changes in the brain.

"In a traumatic brain injury, it's not one specific area that is affected but multiple areas of the brain which are interconnected by axons," said Dr. Lipton, who is also associate professor of radiology, of psychiatry and behavioral sciences, and in the Dominick P. Purpura Department of Neuroscience at Einstein. "Abnormally low FA within white matter has been correlated with cognitive impairment in concussion patients. We believe that high FA is evidence not of axonal injury, but of brain changes that are occurring in response to the trauma."

One year after their brain injury, the patients completed two standard questionnaires to assess their post-concussion symptoms and evaluate their health status and quality of life. "Most TBI studies assess cognitive function, but it is not at all clear if and how well such measures assess real-life functioning," said Dr. Lipton. "Our questionnaires asked about post-concussion symptoms and how those symptoms affected patients' health and quality of life."

Comparing the DTI data to the patient questionnaires, the researchers found that the presence of abnormally high FA predicted fewer post-concussion symptoms and better functioning. The results suggest that the brain may be actively compensating for its injuries in patients who exhibit areas of high FA on DTI.

"These results could lead to better treatment for concussion if we can find ways to enhance the brain's compensatory mechanisms." Dr. Lipton said.

Dr. Lipton's Einstein and Montefiore coauthors are Sara B. Rosenbaum, B.A., Namhee Kim, Ph.D., Ph.D., Craig A. Branch, Ph.D., Richard B. Lipton, M.D., and Molly E. Zimmerman, Ph.D.