Fran Lowry

November 26, 2012

CHICAGO, Illinois — Patients with mild traumatic brain injury who demonstrate abnormally high fractional anisotropy (FA) on diffusion tensor imaging (DTI) have fewer postconcussion symptoms and a better quality of life after their injury than do patients with low FA, according to research presented here at the Radiological Society of North America 98th Scientific Assembly and Annual Meeting.

The finding comes from a large ongoing study of people with mild traumatic brain injury that has shown that low FA on DTI indicates more pathology after concussion, said lead author Michael Lipton, MD, PhD, from the Gruss Magnetic Resonance Research Center at the Albert Einstein College of Medicine, and medical director of magnetic resonance imaging (MRI) at the Montefiore Medical Center, the Bronx, New York.

Dr. Michael Lipton

DTI is a special MRI technique that measures the flow of water molecules within and along axons in the brain's white matter. Low FA indicates relatively disorganized movement of water molecules; high FA indicates more organized movement of water molecules, he explained.

"Low FA has been shown to be associated with worse outcomes after concussion, but...we found that the higher the FA, the greater the likelihood of having fewer postconcussion symptoms and a better health-related quality of life a year after the injury," Dr. Lipton told Medscape Medical News.

Dr. Lipton and his team set out to measure health-related quality of life and postconcussion symptoms 1 year after mild traumatic brain injury in 17 patients who had presented to their emergency department.

Most injuries were a result of assault or motor vehicle accidents.

DTI was performed twice: within 2 weeks of the injury and a year later. Patients completed 2 standard questionnaires to assess their postconcussion symptoms and evaluate their quality of life.

The researchers found that patients who had abnormally high FA had fewer postconcussion symptoms and better health-related quality of life than those with low FA, as shown by better mobility control (P = .024) and psychological functioning (P = .007).

"Right now, we don't know what this means. We don't have the mechanism nailed down, but the hypothesis we are putting forward to explain this is that the increase in FA may represent a compensatory change in the brain, or neuroplasticity," Dr. Lipton explained.

Compensatory Brain Changes

Often, when there is a loss of function due to trauma, stroke, or other disorders, the brain compensates by forming new networks or connections between neurons, Dr. Lipton said.

 
The injured brain is compensating in some way. Dr. Michael Lipton
 

"The high FA may represent this type of neuroplasticity. The way I conceptualize this is if you are driving to work one morning and the bridge you have to go over has collapsed, you have to devise another route to get around the problem. If that route is set up correctly, you might be able to get to your destination reasonably efficiently. The abnormally high FA that we found in some of these patients might mean that the injured brain is compensating in some way," he said.

These findings, which Dr. Lipton stressed are preliminary and need to be confirmed, could open the door to a different approach to the treatment of mild traumatic brain injury.

"Treatment of traumatic brain injury has been and continues to be largely focused on healing and fixing the injury. What we are showing here is that a lot of what determines the outcome might also be dependent on this compensatory component. So treatment could evolve and, rather than solely focusing on trying to repair the damage, improving outcomes might involve developing new drugs to enhance this compensatory response," he said.

 
This could potentially be a game changer in terms of the way we conceptualize the treatment of traumatic brain injury. Dr. Michael Lipton
 

"This could potentially be a game changer in terms of the way we conceptualize the treatment of traumatic brain injury," he added.

Medscape Medical News invited Max Wintermark, MD, chief of neuroradiology at the University of Virginia in Charlottesville, to comment on this study.

Dr. Wintermark described the study results as "promising," and said that DTI could potentially be used as a biomarker to monitor patients after traumatic brain injury and to guide their rehabilitation.

"There are a lot of factors that influence the rehabilitation of patients after brain injury. It would be extremely helpful for physicians to have some kind of measurement to help them know if what they are doing is helping the patient," he said.

Currently, we have to "wait 1 year to see if what we are doing is actually working; if it is not, we have basically wasted a year. Having a marker that would quickly tell us if we are on the right track would allow us to tailor our rehabilitation program to the patient," he added.

Dr. Lipton and Dr. Wintermark have disclosed no relevant financial relationships.

Radiological Society of North America (RSNA) 98th Scientific Assembly and Annual Meeting: Abstract SSC11-03. Presented November 26, 2012.

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