Over 17 million Americans suffer a mild traumatic brain injury each year, 15 percent of which suffer from symptoms that persist after three months. A recent study published in the journal Radiology has revealed that men have a significantly longer road to recovery following a concussion compared to women. This research was made possible thanks to the help of diffusion tensor imaging (DTI), a popular magnetic resonance imaging (MRI) technique used to diagnose neurological conditions.
"MRI and CT brain images of concussion patients are often normal," assistant professor of neuroradiology at the University of Pittsburgh School of Medicine, Dr. Saeed Fakhran, said in a statement. "Diffusion tensor imaging is the first imaging technique that shows abnormalities associated with concussion, because it is able to see white matter tracts at a microscopic level."
Fakhran and his colleagues investigated the medical records of 69 patients who suffered a mild traumatic brain injury between 2006 and 2013. Records included brain imaging results of 47 males (average age of 17) and 22 females (average age of 16). Each patient received computerized neurocognitive test and DTI of the brain. DTI brain scans revealed abnormalities within the uncinate fasciculi (UF), a tract of white matter that connects the brain’s frontal and temporal lobes. The unit of measurement produced by DTI is known as fractional anisotropy (FA).
Sixty-eight percent of the male patients suffered their concussion while playing a sport, compared to 45 percent of the female patients. Patients were at a higher risk for a recovery time that lasted longer than three months as their UF FA values decreased. Male patients’ UF FA values were significantly lower than females. The average recovery time for female patients who suffered a concussion was marked at 26.3 days, compared to male patients who took an average of 66.9 days to recover.
"There's prognostic value in DTI for both children participating in sports as well as for professional athletes," Fakhran added. "Lower FA values in the uncinate fasciculi could offer a metric for evaluating the severity of mild traumatic brain injuries and predicting clinical outcome. We're not at the point where DTI can provide individual prognoses yet, but that's the hope and goal."
DTI is considered an advanced form of MRI used to examine microscopic changes in the brain’s white matter. Nerve fibers found in white matter known as axons act like communication centers that connect areas of the brain. FA values measure the movement of water molecules along these axons. When water movement is less random and measures high FA values it is considered healthy white matter. As water movement becomes random and FA values decrease, a concussion patient is more likely to suffer from cognitive impairment.
"Male gender and UF FA values are independent risk factors for persistent post-concussion symptoms after three months and stronger predictors of time to recovery than initial symptom severity or neurocognitive test results,” Fakhran added. “The potential of DTI and UF FA to predict outcome after concussion has great clinical impact. Currently, we are heavily reliant on patient reporting, and patients may have ulterior motives, such as wanting to get back to play. But you can't trick an MR scanner."
Source: Yaeger K, Collins M, Alhilali L, Fakhran S. Sex Differences in White Matter Abnormalities after Mild Traumatic Brain Injury: Localization and Correlation with Outcome. Radiology. 2014.