Caroline Helwick

October 15, 2013

NEW ORLEANS, Louisiana — Despite self-reports of recovery after concussion, 40% of college football players still had statistically significant impairments on postconcussion cognitive testing, a study from Columbia University has found.

Subtle postconcussion cognitive impairment is under-recognized yet easily identifiable by neuropsychiatric testing, said Tanzid Shams, MD, a pediatric neurologist at Tufts Medical Center, Boston, Massachusetts. Dr. Shams conducted the research while at Columbia University, New York, New York. He now runs a sports concussion program at Tufts.

"Of 70 athletes with concussions who reported a resolution of symptoms, 28 still had deficits on neuropsychological testing — a decline in the Z-score of more than 0.5, which was statistically significant," Dr. Shams told Medscape Medical News.

Meaningful objective thresholds for cognitive impairment after a sports concussion have not been established, even though computer-based neuropsychological testing is becoming the standard of care in many sports settings. In this study, Dr. Shams and colleagues sought to identify differences in cognitive function based on computerized neuropsychological testing among Columbia University football players before and after a first concussion. Their ultimate goal is to identify objective, numeric criteria that can be used as benchmarks for concussion severity and return-to-play guidelines.

They presented their findings here at the American Neurological Association (ANA) 2013 Annual Meeting.

Postconcussion Z-Scores

The researchers reviewed data on 436 Columbia University incoming football players from 2000 to 2011. Baseline data included the Headminder Concussion Resolution Index (CRI) neuropsychological assessment. The CRI was repeated after any concussion, at least 24 hours after injury, and then after the athlete reported a resolution in symptoms. The CRI uses tests such as symbol search, digit symbol, and trail-making to analyze memory and reaction time and to create a Z-score for each test and a composite Z-score of overall cognitive performance.

Of the 436 football players, 148 (34%) reported a history of concussions, which averaged 1.7 per player for a total of 258 for the group. After entry into the Columbia football program, 70 concussions were identified over the course of 11 football seasons.

"We identified 70 concussions among 436 athletes, and despite subjective reports of recovery, at their lowest scores nearly 40% of these concussed players had statistically significant, and likely clinically significant, impairment, which was identified on cognitive testing," Dr. Shams said.

The median time to return to play was 12 days for players with no history of concussion and 10 days for players with a history of concussion.

We think it's remarkable that 40% of athletes who say they are 'fine' still have neuropsychological deficits on testing. Dr. Tanzid Shams

The first postconcussion composite Z-scores (an average of 9 separate assessments) significantly declined from baseline (P < 0.001). Twenty-eight of the 70 (39%) declined at least 0.5 unit. Overall, 10% of concussed players did not return to sport. Of the athletes with the largest decline in cognitive test score, 24% did not return to sport.

"We think the way these data were collected is very important. If an athlete says he is still having headaches or balance problems, and he tests poorly, that tells you very little. But in this case, athletes reported resolution of symptoms but the deficits were still there," Dr. Shams said.

"The goal of our study was to identify objective criteria for returning athletes to play. The American Academy of Neurology and other groups are putting out guidelines, but these are still dependent on clinical assessment," he said. "Our goal was to come up with objective numeric criteria that show the extent of the decline in neuropsychological testing and to determine whether a decline of 0.5 in the Z-score, or 25% from baseline, or one standard deviation, is significant," he said.

If a trend is identified and confirmed in a larger population, objective criteria could be incorporated into the return-to-play guidelines.

"Meaningful Study"

Mark Goldberg, MD, the Linda and Mitch Hart Distinguished Chair in Neurology at the University of Texas Southwestern Medical Center, Dallas, told Medscape Medical News that this study could represent a real advance in how concussions are evaluated and athletes are managed.

"We are very interested in understanding how we should manage concussions, which are a common problem and one for which we do not have a standardized assessment. The problem is that researchers have not asked a question that is meaningful. A lot of work in this field just examines players who say they are not okay, and then the testing just confirms that. That is not very helpful," Dr. Goldberg pointed out.

"What I love about this study is that it asks the right question," he said. "It is much more useful to be able to make an assessment in cases where you are not sure. It identifies players who need special attention."

Dr. Shams and Dr. Goldberg have disclosed no relevant financial relationships.

American Neurological Association (ANA) 2013 Annual Meeting. Abstract #M902. Presented October 14, 2013.


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