Rapid Number Reading Test Offers Possible Flag for Mild TBI: Is it Ready for Use in the Field?
ARTICLE IN BRIEF
Investigators report that the King-Devick is an accurate and reliable method for identifying athletes with head trauma, and may be a strong candidate for quickly assessing concussion at sports events.
A two-minute test used to assess reading errors could also prove to be a fast and reliable screening method for detecting concussion in athletes at the sidelines of sporting events, investigators suggested in a Neurology paper first published online on Feb. 2.
The researchers recruited boxers and mixed martial arts competitors to spar and be assessed before and after their bouts with the King-Devick (K-D) test, which involves reading rapidly a series of single digits presented left to right on printed cards. One practice card precedes three test cards and instructions are standardized.
The University of Pennsylvania investigators found the test was easier to use and more reliable than others currently used on sports sidelines. But experts not involved with the study cautioned that the K-D test, which is being marketed on the Internet, is not yet ready for use in the field. [The study investigators have no financial interests in the company that markets the test.]
Laura J. Balcer, MD, said that her colleagues had used the K-D test to diagnose reading disorders in children, and thought it could be useful for detecting head trauma. “The visual system is widely involved in brain function, and eye movement changes are a marker for worse outcome” in concussion, said Dr. Balcer, professor of neurology at the Hospital of the University of Pennsylvania.
“We started with a cohort where head injury is obvious,” said Dr. Balcer in a telephone interview with Neurology Today. In the study bouts, a ringside physician with expertise in these sports inferred head trauma based on blows to the head or loss of consciousness. There were no imaging studies. Examiners were not told who had sustained a blow to the head or loss of consciousness.
Thirty-nine boxers and mixed martial arts practitioners were recruited by their gym managers to participate in three rounds of sparring, for a total of nine minutes. Standard headgear and gloves were used. Testing was carried out twice: 15 minutes before the fighting session for the boxers as well as on the day prior to the martial arts event, and once again after the session was over for both boxers and martial arts fighters.
Post-bout K-D scores were significantly higher (worse) for eight fighters who had head trauma during the match compared with 31 who showed no signs of head trauma. The four fighters who lost consciousness showed the greatest worsening in K-D scores from prefight to post-fight. A distinguishing characteristic for fighters with head trauma was a worsening of K-D scores by five seconds or more.
As a comparison, the researchers also administered a more comprehensive test for traumatic brain injury called the Military Acute Concussion Evaluation (MACE), which takes about 15 to 20 minutes to administer and involves three components: a cognitive history, memory and orientation testing, and a neurological screening. Boxers who sustained head trauma during their fight were given the MACE test immediately after the sparring session followed by the K-D test. All of the mixed martial artists were given the MACE test after their bouts.
The K-D scores seemed to be consistent with the MACE results. Failure on the MACE test (with scores less than 25 out of a maximum of 30 points) was associated with worse post-fight K-D scores and with greater worsening of K-D scores from pre- to post-bouts.
Inter-rater agreement was good, Dr. Balcer said. Reliability for K-D measurements pre- and post-fight was also excellent among participants who did not have head trauma during their match (95% CI, 0.87–1.0). This finding suggests that K-D measurements are stable over the short term in the absence of intervening concussion.
Ongoing studies at the University of Pennsylvania will be establishing norms for the K-D test in college athletes. “We need to move forward with prospective studies that examine the validity of the screens being used to diagnose concussion,” said another study author Steven L. Galetta, MD, Ruth Wagner Van Meter and J. Ray Van Meter Professor of Neurology and chief of the Neuro-Ophthalmology Division at the University of Pennsylvania School of Medicine.
“This test does examine a brain function that is consistent with the injury of concussion,” said Jeffrey S. Kutcher, MD, assistant professor of neurology at the University of Michigan-Ann Arbor, and director of the Michigan Neurosport Program. “With the test measuring a disruption of the ability to track visually, it makes sense that the K-D test would be applied to concussion,” he said. However, he added: “Given the lack of a ‘gold standard’ clinical test for diagnosing concussion, we must be very careful when these tools are applied in the clinical setting.”
“I want to be very clear,” said Dr. Kutcher, who is co-chair of the AAN Section on Sports Neurology. “None of these tests should be used to make a diagnosis of concussion or as a sole determinant of when it is safe to return to play.”
“This paper hints that the K-D test may be clinically useful but only within the narrowly defined parameters of this study,” he continued, “with a pre-test followed very closely in time by the post-injury test. In the practical setting, baseline testing is done pre-season, weeks or months before an injury occurs. This study does not speak to the usefulness of the K-D test in most sports injury scenarios.”
Dr. Kutcher said he would also like to have a test account for the possible influence of factors such as exertion and dehydration after sustained play, as well as motivation and distractibility. “For those reasons I don't think this test is ready for widespread clinical use.”
William P. Meehan III, MD, director of the Sports Concussion Clinic in the Division of Sports Medicine at Children's Hospital in Boston, said that he tests his athletes during circumstances as similar as possible as when they would be sustaining an injury, to include dehydration and fatigue. “I would have done (the pre-test) after one sparring session with no head blows, or during a workout,” he commented about the study.
Dr. Meehan noted that the available computerized assessments for concussion are sensitive, if more time-consuming, and can tell if an athlete is trying to “throw” the test by purposefully scoring low, in order to avoid a later concussion red flag. “Can they detect that with the K-D?” he asked, adding that someone could possibly go slowly on purpose.
He noted that the report does not look at concussion specifically. “We usually don't call a blow to the head a concussion,” he said, “although there may be some subtle cognitive effects even with this, as their test suggests.”
“I look forward to the results from the larger cohort that the investigators are testing,” Dr. Meehan said. “I think their results are promising as a brief sideline assessment,” he concluded.
Dr. Kutcher noted that the K-D test is being marketed on the Internet (see kingdevicktest.com). “I ran across this,” he said, “and was disappointed to see the test being sold commercially with so little data to support its use.”
“When it comes to preventing concussions,” Dr. Kutcher said, “the most important advice we can give is to use proper technique, to play with the proper equipment and play by the rules. Concussions will happen,” he said. “Recognize when they do, and allow for adequate recovery before returning to play.”
“There are simple steps we can take,” Dr. Kutcher said, “education is the key, and neurologists must continue to be more involved in the conversation.”