Tag Archives: gender
A study of concussion patients using diffusion tensor imaging (DTI) found that males took longer to recover after concussion than females did. Results of the study, which show that DTI can be used as a bias-free way to predict concussion outcome, are published online in the journal Radiology.
Each year, more than 17 million Americans suffer a mild traumatic brain injury (mTBI), more commonly known as a concussion, of which approximately 15 percent suffer persistent symptoms beyond three months.
Assessing outcomes and recovery time after concussion can be very subjective. Typically, physicians must rely on patient cooperation to assess injury severity.
“MRI and CT brain images of concussion patients are often normal,” said Saeed Fakhran, M.D., assistant professor of neuroradiology at the University of Pittsburgh School of Medicine. “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.”
Saeed Fakhran, M.D.
DTI is an advanced form of MRI that allows researchers to assess microscopic changes in the brain’s white matter. The brain’s white matter is composed of millions of nerve fibers called axons that act like communication cables connecting various regions of the brain. DTI produces a measurement, called fractional anisotropy (FA), of the movement of water molecules along axons. In healthy white matter, the direction of water movement is fairly uniform and measures high in FA. When water movement is more random, FA values decrease. Abnormally low FA is associated with cognitive impairment in patients with brain injuries.
The research team examined the medical records and imaging results of 69 patients diagnosed with mTBI between 2006 and 2013, including 47 males and 22 females, and 21 controls consisting of 10 males and 11 females (median age of males: 17; median age of females: 16). Of the 47 males with mTBI, 32 (68 percent) were injured while playing a sport, as were 10 of the 22 females (45 percent).
All patients underwent the same evaluation, including a computerized neurocognitive test and DTI of the brain. The DTI scans of the mTBI patients revealed abnormalities within the uncinate fasciculi (UF), a white matter tract that connects the frontal and temporal lobes of the brain. Although its exact role is controversial, the UF tract is believed to allow temporal lobe-based memory associations to modify behavior though interactions with another area of the brain.
The DTI scans revealed that compared to the female mTBI patients, the male mTBI patients had significantly decreased UF FA values.
“In the future, we would like to look at the issue of gender and concussions more in depth to determine who does better and why,” Dr. Fakhran said.
A statistical analysis of the data revealed that UF FA value was a stronger predictor of recovery time than initial symptom severity based on neurocognitive testing. The most substantial risk factor for a recovery time longer than three months was decreased UF FA. Male gender also directly correlated with increased recovery time.
“The potential of DTI and UF FA to predict outcome after concussion has great clinical impact,” Dr. Fakhran said. “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.”
The average time to symptom recovery for all concussion patients was 54 days. However, compared to the female patients who recovered in an average of 26.3 days, recovery was significantly longer for the male patients (an average of 66.9 days), irrespective of initial symptom severity.
“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,” Dr. Fakhran said.
He said results of the study indicate a potential role for UF FA values in triaging concussion patients in the future.
“There’s prognostic value in DTI for both children participating in sports as well as for professional athletes,” he said. “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.”
Much has been printed suggesting the existence of gender-related differences in athletes’ responses to sports-related concussions, including differences in concussion incidence, symptoms reported, and scores on neurocognitive tests before and after injury.
Nevertheless, findings have not been unanimous, and no guidelines regarding gender-specific strategies for prevention or treatment of sports-related concussions have been developed.
Researchers at Vanderbilt University, the University of Albany, and ImPACT Applications, Inc., set out to review symptoms and neurocognitive findings in male and female high-school soccer players to see if they could verify such discrepancies. The researchers were unable to do so. Full details of their results can be found in “Response to acute concussive injury in soccer players: is gender a modifying factor? Clinical article,” by Scott Zuckerman, MD, and colleagues, published online in the Journal of Neurosurgery: Pediatrics (http://thejns.org/doi/full/10.3171/2012.8.PEDS12139).
When asked why the researchers decided to study whether gender is a modifying factor in soccer-related concussions, Dr. Zuckerman stated, “The number of females playing sports has exponentially increased in recent decades, as has the controversy regarding concussion management in males versus females. Our aim was to identify gender differences in neurocognitive testing in a highly regulated, homogeneous population, controlling for several possible modifying factors such as the number of prior concussions and the sport. Prior studies utilized mixed groups of high school and collegiate athletes, without controlling for several potential confounders. Dr. Solomon and Dr. Sills are experts in their field, and with their guidance, we thought this would be a relevant question to answer.”
The authors examined information on symptoms and neurocognitive scores contained in databases covering athletes in central Tennessee and western Pennsylvania who had sustained concussions during soccer competitions. The researchers selected 40 male and 40 female patients who were matched, as closely as possible, for age, medical/psychiatric history, years of education, lack of special education assistance, history of psychiatric treatment, number of prior concussions, timing of pre- and post-concussion testing, and sport (all engaged in soccer). The matching process was undertaken to bypass any unforeseen confounders to observe male-female differences in neurocognitive-dependent variables. In each case, the researchers were able to collect data on baseline and post-concussion symptoms and neurocognitive scores that had been obtained using ImPACT (Immediate Post-concussion Assessment and Cognitive Testing), a commercially available software program used to evaluate sports-related concussions.
Based on the results of several earlier studies on gender-related differences in sports-related concussions, the authors tested the following four hypotheses: 1) female soccer players would report more symptoms at baseline and after a concussion; 2) female players would have better baseline verbal memory scores; 3) male players would have better baseline visual memory scores; and 4) female players would have higher levels of neurocognitive impairments immediately following a concussion.
To test these hypotheses, the researchers examined baseline and post-concussion scores of verbal memory, visual memory, visual-motor speed, reaction time, and impulse control, as well as the total number of symptoms that were reported. Using statistical analyses, the authors were unable to verify their first three hypotheses. The only significant gender-related difference that they could identify was that female soccer players reported a greater number of symptoms post-concussion. When asked if the findings were surprising, Dr. Zuckerman commented: “We were somewhat surprised and were not sure what to expect in such a tightly controlled population. Our hypothesis was that females would experience greater levels of acute, post-concussive neurocognitive impairment than males, fitting with what most of the prior literature says, but we found virtually no difference between males and females.”
With a look toward the future, Dr. Zuckerman added that, “It seems that there are different types of concussions that occur in different sports, possibly based on mechanism of injury and equipment. This study would be equally interesting to perform in a sport where headgear is routinely used, such as hockey.”
The authors clearly lay out the results of their investigation, note differences between methods used in their study and those used in earlier investigations, and discuss the implications of their negative findings for a broader discussion of gender as a modifying factor in sports-related concussions.