Sports-related concussion has received increasing attention as a cause of short- and long-term neurologic symptoms among athletes. The King-Devick K-D test is based on measurement of the speed of rapid number naming reading aloud single-digit numbers from 3 test cards , and captures impairment of eye movements, attention, language, and other correlates of suboptimal brain function. We investigated the K-D test as a potential rapid sideline screening for concussion in a cohort of boxers and mixed martial arts fighters. The K-D test was administered prefight and postfight. Differences in postfight K-D scores and changes in scores from prefight to postfight were compared for athletes with head trauma during the fight vs those without.
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Sports-related concussion has received increasing attention as a cause of short- and long-term neurologic symptoms among athletes. The King-Devick K-D test is based on measurement of the speed of rapid number naming reading aloud single-digit numbers from 3 test cards , and captures impairment of eye movements, attention, language, and other correlates of suboptimal brain function. We investigated the K-D test as a potential rapid sideline screening for concussion in a cohort of boxers and mixed martial arts fighters.
The K-D test was administered prefight and postfight. Differences in postfight K-D scores and changes in scores from prefight to postfight were compared for athletes with head trauma during the fight vs those without. Those with loss of consciousness showed the greatest worsening from prefight to postfight. High levels of test-retest reliability were observed intraclass correlation coefficient 0. The K-D test is an accurate and reliable method for identifying athletes with head trauma, and is a strong candidate rapid sideline screening test for concussion.
Sports-related concussion has received increasing attention in the lay press, but has been a topic of interest in the medical literature for nearly a decade.
Since detecting early signs of concussion can improve outcomes, 8 — 20 there is a need for a rapid screening test to assess athletes who may have had a concussion. The King-Devick K-D test is based on measurement of the speed of rapid number naming. We investigated the K-D test as a potential rapid sideline screening for concussion in a cohort of boxers and mixed martial arts MMA fighters.
We determined if athletes with head trauma and loss of consciousness during matches differed in terms of their postfight K-D time scores or with regard to changes in scores from prefight to postfight. For this cross-sectional study, boxers and MMA fighters were recruited and enrolled prior to sparring sessions and matches conducted in the Boston, MA, area. Boxers were amateurs recruited by their gym manager and invited to participate in 3-round sparring sessions.
Standard and routine headgear and sparring-grade boxing gloves were worn. Written informed consent was obtained from all participants and principles outlined in the Declaration of Helsinki were followed. The K-D test is based on measurement of the speed of rapid number naming.
Standardized instructions are used, and the test requires less than 2 minutes to administer. The K-D test includes one practice demonstration card and 3 test cards, as shown in figure 1.
To perform the K-D test, participants were asked to read the numbers on each card from left to right as quickly as possible but without making any errors.
The sum of the 3 test card time scores constituted the summary score for the entire test, the K-D time score. Numbers of errors made in reading the test cards were recorded. To perform the K-D test, participants are asked to read the numbers on each card from left to right as quickly as possible but without making any errors. Following completion of the demonstration card upper left , subjects are then asked to read each of the 3 test cards in the same manner.
The times required to complete each card are recorded in seconds using a stopwatch. The sum of the 3 test card time scores constitutes the summary score for the entire test, the K-D time score. Numbers of errors made in reading the test cards are also recorded; misspeaks on numbers are recorded as errors only if the subject does not immediately correct the mistake before going on to the next number. This test consists of 3 components, including a cognitive history, memory and orientation testing, and a neurologic screening.
This test requires 15—20 minutes. A total MACE score less than 25 is considered to represent clinically relevant neurocognitive impairment and require further evaluation for brain injury. All boxers were tested at ringside immediately before a 3-round sparring session. Corrections were made for near vision as needed. Boxers were given standardized instructions for the K-D test. For purposes of determining test-retest reliability of precompetition K-D scores, all boxers were tested twice within a minute period before their sparring session by the same examiners.
After the individual 9-minute sparring sessions, each boxer was retested once using the K-D test. Boxers who sustained head trauma during their fight were given the MACE test immediately after the sparring session followed by the K-D test. Among boxers, the MACE test was given only to those with head trauma. Fighters were tested on the day before the MMA event at the time of their weigh-ins.
Protocols for K-D testing were the same as those used for the boxers described above. Postfight testing was delayed by 30 to 60 minutes for 3 fighters due to nonhead injuries. MACE testing in this group was performed for all fighters in the cohort.
Statistical analyses were performed using Stata Given the common endpoints of head trauma and LOC, and their uniform definitions for both the boxers and MMA fighters, data were analyzed based on the combined study cohort.
Differences in postfight K-D time scores and changes in scores from prefight to postfight were compared for participants with head trauma during the fight vs those without using the Wilcoxon rank sum test with exact variances. Among participants with head trauma, those with vs without LOC were compared similarly. Test-retest reliability was estimated for 2 prefight K-D test measurements by the intraclass correlation coefficient ICC ; ICCs were also used to examine agreement between prefight and postfight scores among participants without head trauma.
With the exception of one participant, all fighters and boxers were men. Prefight K-D scores were similar across groups, with slightly lower mean time scores noted for the second prefight testing session table 2. Postfight K-D time scores were significantly higher worse for participants who had head trauma during the match The median change in scores from prefight to postfight for participants who did not have head trauma was a 1.
Participants with LOC also had the greatest worsening of scores from prefight to postfight, with a median increase of The numbers of errors were very few, with one participant making 2 errors and another one error on postfight testing. However, both of the participants who made errors were boxers who had head trauma.
This observation likely reflects learning effects for the K-D test. The postfight K-D score distributions showed some overlap between the groups with and without head trauma figure 2. However, there was no overlap in the distribution of changes in scores from prefight to postfight, with a substantial gap between the worst change in the no head trauma group and the best change in the head trauma group.
As demonstrated in table 1 , the lower limit of the range of worsening of K-D time scores for participants with head trauma was 5.
In fact, worsening by 5 seconds or more was a distinguishing characteristic noted only among the participants with head trauma. The lines in the box represent the medians, and boxes delineate the interquartile range 25th—75th percentiles.
Whiskers represent the range of observations minus outliers no outlier values in this sample. Results of this study demonstrate that the K-D test is an accurate and reliable method for identifying athletes with head trauma, and is a strong candidate as a rapid sideline screening test for concussion.
High degrees of test-retest reliability were noted for the K-D test in this study. Postfight time scores in this cohort of boxers and MMA fighters were greater worse postfight for participants who had head trauma during their match.
Changes in scores from prefight to postfight also reflected this pattern and showed more separation between those with and without head trauma than the postfight scores alone. Worsening by 5 seconds or more was a distinguishing characteristic noted only among the participants with head trauma, suggesting that this threshold may be a useful cutoff for exploration in future studies as a criterion for having an athlete stop play pending medical evaluation for concussion.
Closed head injury, even in mild form, is a leading cause of both short-term and long-term cognitive impairment among athletes, particularly for those in contact sports such as football, boxing, soccer, rugby, and hockey. The recognition and management of concussion in athletes can be difficult for a number of reasons. Symptoms of mild concussion are typically quite subtle and may go unnoticed or overlooked by the athlete, team medical staff, or coaches.
Thus, while structural neuroimaging techniques are insensitive to the effects of concussion, more advanced fMRI techniques have been able to document damage and to examine the window of metabolic brain vulnerability during which a second concussion could be even more dangerous. To the extent that the K-D test captures saccadic eye movements among other important elements of rapid number naming, these data suggest that this quick screening test will be helpful in identifying athletes with signs of concussion.
Impaired eye movement function, particularly for those reflecting subcortical pathways, correlated well with severity of postconcussive symptoms and with limitation of activities of daily living. In another study, early eye movement function at 1 week was shown to predict development of postconcussion syndrome.
While the manifestations of postconcussion syndrome are best captured by extensive testing batteries such as ImPACT, 37 and may be influenced by intellectual ability or depression, tests of rapid number naming such as K-D represent an objective measure.
Because the K-D test captures many aspects of function, including subcortical subconscious pathways that extend beyond eye movements, this test may help coaches and trainers with game decisions regarding removal of a player who may have been concussed. Since our study cohort consisted of boxers and MMA fighters, head trauma that occurred was observable and overt. In other sports such as football, closed head injury and concussion could occur in the context of plays involving many individuals, and head trauma may not be as readily detected.
Worsening of K-D scores in this setting might be helpful for determining if a meaningful head blow has taken place.
Another important aspect of evaluating a potential screening test is the correlation of scores with an established battery of tests that measure the construct under study.
Ongoing large-scale longitudinal studies of collegiate athletes are examining the relation of K-D test scores and changes in scores over the course of a season with ImPACT and other formal cognitive testing.
Correlations between postfight MACE scores as a continuous variable and K-D scores were also strong, thus providing preliminary evidence that K-D test scores reflect more global aspects of cognitive function in the setting of acute mild closed head injury and concussion.
In order for the K-D test to be used effectively over time and to be administered by different testers, such as athletic trainers, the interrater and test-retest reliability of this measure must be assessed. Results of our study show that K-D test time scores have a high degree of test-retest reliability, with ICCs of 0. Reliability for K-D measurements prefight vs postfight was also excellent among participants who did not have head trauma during their match ICC 0.
This finding suggests that K-D measurements are stable over the short term in the absence of intervening concussion. The relatively uncommon occurrence of head trauma in our boxing cohort must be viewed in context of the fact that sparring sessions, rather than actual boxing matches, were assessed in this study. Boxers are at high risk for concussion and for more long-term manifestations of CTE, formerly termed dementia pugilistica. The K-D test, based on measurement of the speed of rapid number naming, can capture impairment of eye movements, attention, language, and other areas that correlate with suboptimal brain function.
Data from this investigation demonstrate that the K-D test is an accurate and reliable method for identifying athletes with head trauma.
The K-D test represents a strong candidate rapid sideline screening test for concussion, and has particular relevance to contact sports including football, soccer, hockey, MMA, and boxing. Prospective studies of collegiate athletes that are ongoing at the University of Pennsylvania will establish large-scale K-D test norms and expected ranges of precompetition scores for this age group, and will further investigate the capacity for K-D scores to capture closed head injury and concussion.
Editorial, page Statistical analysis was conducted by Dr. Balcer and Dr. Galetta, J. Barrett, Dr. Allen, Dr. Madda, Dr. Delicato, Dr.
King Devick Test
Quickly recognize impaired eye movements on the sidelines with King-Devick Test in association with Mayo Clinic. The King-Devick Test is a two-minute rapid number naming assessment in which an in individual quickly reads aloud single digit numbers and evaluates impairments of eye movements, attention and language function Concussion, The King-Devick test of rapid number naming for concussion detection: meta-analysis and systematic review of the literature, Peer-reviewed research has shown that adding a vision-based performance measure to cognitive and balance testing enhances the detection capabilities of current sideline concussion assessment Journal of Neuro-Ophthalmology, Adding Vision to Concussion Testing: A Prospective Study of Sideline Testing in Youth and Collegiate Athletes Any worsening of King-Devick Test from baseline indicated a five-times greater likelihood of concussion Concussion, The King-Devick test of rapid number naming for concussion detection: meta-analysis and systematic review of the literature, Some off-label uses of devices described in the peer-reviewed scientific research have not been cleared by FDA. Contact Us Here.
The King-Devick test as a determinant of head trauma and concussion in boxers and MMA fighters
Although the King-Devick K-D test has been used frequently in assessing sports related concussion early after injury, its characteristics over time after injury and in patients with prolonged persistent symptoms are unknown. The purpose of this paper was to: evaluate the ability of the K-D Test to distinguish patients seen early after concussion from those with symptoms persisting more than 3 months compared to controls, assess changes in the K-D test times over time after concussion, and determine the relationship of K-D times to the Stroop Color and Word Test scores. We performed cross-sectional comparisons of patients with recent concussive brain injury acute group and those with symptoms persisting more than 3 months to healthy controls on the K-D test, the Sports Concussion Assessment Tool 3 SCAT3 , and the Stroop Color and Word Test. Longitudinal comparisons of the acute group over time within the first month after injury were also made. K-D times at the second visit for the acute group were similar to those of controls While SCAT3 scores improved over time in the acute group, the K-D scores did not change between the first and second visit