April 29, 2014

PHILADELPHIA — A simple vision test performed on the sidelines can improve the identification of concussion in sports players who have experienced a head injury, a new study suggests.

"The visual pathways are commonly affected in concussion," said author Laura Balcer, MD, New York University School of Medicine. "Adding a vision-based test to evaluate athletes on the sidelines may allow us to better detect more athletes with concussion more quickly. This is particularly important since not all athletes reliably report their symptoms of concussion, including any vision problems."

Coauthor James Clugston, MD, team physician, University of Florida Athletic Department, Gainesville, explained to Medscape Medical News, "We have been doing standard tests based on balance symptoms and cognition tasks but we are not altogether sure that we are picking up subtle concussion injuries with these. So we have started using this vision test to see if we can improve detection rates.

"Sometimes, the athlete does not know they are concussed or they may hide symptoms so as to get back into the game quickly, so we are looking for a test to pick up concussions like this that may not have been identified before."

The study was presented here at the American Academy of Neurology (AAN) 66th Annual Meeting.

100% Detection With Combination

The King-Devick test involves the reading of a series of numbers from index cards or an iPad screen, and it takes about 1 minute. This is done at the start of the season as the baseline assessment. After injury the same set of tests are conducted — often on the side of the pitch — and if the time taken is longer than at baseline, then concussion is diagnosed. The test would be repeated every day until the baseline time was reached.

Dr. Clugston noted that there was not a set reduction in score that was classified as concussion; rather, anything less than baseline should raise concern. "After exercise, scores will usually be the same as or faster than baseline. Any slowing in the time taken to complete the tests was the definition of concussion used in this study."

For the study, baseline data for 217 athletes aged 18 to 22 years playing on the University of Florida men's football, women's soccer, and women's lacrosse teams were collected. These included scores on the King-Devick vision test, along with the standard tests currently used: the Standardized Assessment of Concussion (SAC) and Balance Error Scoring System (BESS). The Post-Concussion Scale (PCS) was also used to assess symptom reporting. These tests were performed again after head injury, and analyses examined changes in scores from baseline to postinjury.

Results showed that among 30 athletes with first concussion during their athletic season, 79% showed worsening of time scores in the King-Devick vision test. In contrast, the SAC test identified 52% of concussions and the BESS test picked up 70%. Combining the King-Devick vision test and SAC captured 89% of concussions, and using all 3 tests identified 100%.

In addition, symptom severity scores on the PCS worsened from baseline with increases in King-Devick scores; among specific symptoms, light and noise sensitivities were particularly well correlated with worsening performance on the vision test. Baseline scores for the ImPACT testing visual motor speed subscore were also worse for athletes who required longer times to complete the King-Devick test at baseline.

"I do think this is enough to recommend this vision test be used routinely," Dr. Clugston commented. "This test is less subjective than some of the other tests used currently. An assessment of balance is always very subjective, and cognition tests can be too. But the vision test just involves reading numbers from a screen as fast you can. It is very simple and less easily manipulated by the athlete. But it is best used in combination with the standard tests."

In a second paper presented here, some of the same researchers, with first author Priya Dhawan, MD, used King-Devick testing preseason, postseason, and immediately following suspected concussion in 141 high school hockey players. All were assessed before and after the season with a computerized cognitive assessment test (Axon Sports).

Additional testing was performed in a subgroup of nonconcussed athletes before and after a game to determine the effect of fatigue and subconcussive hits on King-Devick scores.

Of the 141 players tested, 20 reported head injury. All of these players had immediate postconcussion King-Devick times greater than 5 seconds from baseline (average, 7.3 seconds) and all but 2 had worse postseason scores (46.4 seconds vs 52.4 seconds; P < .05 Wilcoxon signed-rank test).

Eleven nonconcussed players had worse postseason times from baseline (37.6 vs 43.8 seconds). One hundred ten players saw minimal improvement postseason (43.9 vs 42.1 seconds; P < .05) and 51 nonconcussed players assessed before and after a game revealed no significant time change (43.4 v. 42.0 seconds postgame; P < .05).

King-Devick testing accurately identifies real-time, symptomatic concussion in adolescents, the researchers concluded. Scores in concussed players may remain abnormal over time, they note. In addition, the test may detect asymptomatic concussion.

"Athletes should undergo pre- and postseason K-D testing, with additional evaluation real-time to inform the assessment of suspected concussion," Dr. Dhawan and colleagues conclude.

The study was supported by the National Institutes of Health.

American Academy of Neurology (AAN) 66th Annual Meeting. Abstracts S19.006, S11.0031977.


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