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Detecting Concussion in Boxers and Mixed Martial Arts Fighters
Abstract & Commentary
By Wendy S. Vargas, MD, and Steven Weinstein, MD. Dr. Vargas is Pediatric Neurology Fellow, and Dr. Weinstein is Director of the Pediatric Comprehensive Epilepsy Program, Weill Cornell Medical College. Dr. Vargas and Dr. Weinstein do not report any financial relationships relevant to this field of study.
Synopsis: The King-Devick test, if validated in future studies, has the potential of becoming a standard sideline method for identifying athletes who have sustained a brain injury.
Source: Galetta KM, et al. The King-Devick test as a determinant of concussion in boxers and MMA fighters. Neurology 2011;76:1456-1462.
Head impact among boxers and mixed martial arts (MMA) fighters is common. At the ringside, distinguishing incidental blows from those producing brain dysfunction is important in protecting the athletes from receiving a second significant head injury, avoiding the second impact syndrome, and potentially, preventing the long-term consequences of brain trauma. To be useful, the test must be easy and quick to administer, be reliable in identifying dysfunction, have test-retest reliability, and be predictive of future outcome.
The King-Devick (K-D) test has been proposed as a means for ringside assessment of neurologic function. It measures the speed of rapid number naming, and assesses eye movements, attention, and language. A series of single-digit numbers are read aloud from left to right on three test cards. The test is well adapted for use at the ringside, since it takes less than 2 minutes to administer. Reliability in identifying abnormalities was established in this study by comparison to a more comprehensive exam, the Military Acute Concussion Evaluation (MACE). Test-retest reliability was measured by testing each boxer twice, within 15 minutes prior to the sparring session, by the same examiners.
Boxers were amateurs recruited by their gym manager and participated in a 3-round sparring session. MMA fighters participated during a sanctioned MMA event. Data were collected for a total of 39 participants 27 boxers and 12 MMA fighters. Eight of the 39 participants (7 boxers and 1 MMA fighter) sustained head trauma during their respective events. Head trauma was defined as overt blows to the head with or without loss of consciousness; observation was made by an independent physician with prior ringside experience and expertise in boxing and MMA, and the K-D test was administered independently by another individual who was, for the most part, blinded to the clinical status.
Post-fight K-D scores were significantly worse for those with head trauma during the match, particularly for those having loss of consciousness. The post-fight K-D scores correlated well with post-fight MACE scores. Worsening of K-D scores by > 5 seconds was noted only among participants with head trauma. High levels of test-retest reliability were observed.
This is one of the first studies of its kind to attempt to identify and validate a rapid sideline screening test for the detection of concussion in athletes of contact sports. Given the massive media attention over sports-related concussion, and considering that our current guidelines for concussion management are not evidence-based, it is important that studies of this sort merit attention, validation, and replication. It is clear that a quick and practical objective sideline determination of neurological dysfunction after head impact is necessary. A significant strength of this study is the high degree of test-retest reliability for the K-D test. Worsening of K-D score by more than 5 seconds was a characteristic noted only among those participants with head trauma, suggesting this objective change as a threshold for further exploration as one criterion for removing an athlete from further play.
A major limitation of the study is that it does not relate the findings to near- or long-term outcomes, nor is it correlated to other symptoms of concussion. It does not address when it is safe to return the athlete to play. It should be noted that one of the study authors owns stock in the K-D testing company, and has a patent pending on the very test this study is attempting to validate. Nevertheless, the current data suggest that the K-D test is a practical sideline tool that is both accurate and reliable in detecting significant head trauma in athletes. If further studies can validate these preliminary findings, the K-D test will be a strong candidate as a rapid sideline screening test for concussion.