Concussion in athletes was detected with greater accuracy when a simple vision test was added to other established tests in a prospective study of 217 members of the men’s football, women’s soccer, and women’s lacrosse teams at the University of Florida.
All concussive cases were correctly identified when the King-Devick (K-D) test was used in conjunction with the Balance Error Scoring System (BESS), which is part of the Sports Concussion Assessment Tool 3 (SCAT3), Dr. Laura Balcer and her associates reported Feb. 26 in an abstract released in advance of the annual meeting of the American Academy of Neurology in Philadelphia.
Furthermore, differences between baseline assessments and postinjury assessment showed that the K-D test identified a higher percentage of athletes with worsened scores than did the Standardized Assessment of Concussion (SAC) test (79% vs. 52%).
Using the K-D and SAC tests together also was better than using either of the tests alone, with 89% of concussions identified.
In a statement issued by the AAN, Dr. Balcer of the departments of population health and neurology at New York University noted that "the visual pathways are commonly affected in concussion. [And] 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."
The findings add to previous work by Dr. Balcer and her colleagues in a similarly sized cohort of athletes from the University of Pennsylvania varsity football, sprint football, and women’s and men’s soccer and basketball teams (J. Neurol. Sci. 2011;309:34-9), and lend further support for the use of the K-D test as a rapid screening tool to assess players’ concussion during sporting events.
Up to 3.8 million sports-related concussive injuries have been estimated to occur in the United States each year, with diagnosis based on a variety of symptoms and signs that may include headache, unsteadiness, confusion, or behavior that is out of character for the individual concerned. It is important to be able to assess head injuries quickly, as concussion may be a result of a more serious neurological injury that needs emergency hospital treatment.
Unlike other tests for concussion that ideally need to be administered by a medical professional, anyone can administer the K-D test. This, together with the fact it takes less than 1 minute to complete, makes it ideal to use on the sidelines as an objective means of whether a concussive injury warrants more urgent attention.
The K-D test was developed in 1976 and assesses saccade, or the quick, simultaneous movement of both eyes in the same direction, as well as subjects’ language and level of concentration. It involves subjects’ quickly reading aloud a series of single-digit numbers shown to them on three test cards of increasing complexity. Subjects read the test cards from left to right and a stopwatch is used to record the time it takes them to complete each one. A time score is then obtained as the sum of all three test card times.
For the present study, the University of Florida sports teams administered several tests for concussion at the beginning of their seasons and again if concussion was suspected during the season. Thirty athletes experienced a first concussion during their athletic season.
The researchers found that worsening symptom severity scores obtained using the Post-Concussion Scale correlated strongly with increasing time to complete the K-D test (P less than .001).
"Among specific symptoms, light and noise sensitivities were particularly well correlated with K-D worsening," Dr. Balcer and her colleagues wrote in their abstract.
Furthermore, athletes who took longer to complete the K-D test at baseline had worse baseline score for visual motor speed assessed using the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) scale, which was conducted as part of routine clinical practice for concussion management but not diagnoses.
"The implications are that adding a vision-based test to sideline concussion assessment enables us to have a group of tests – a composite – that, when used together, can potentially help identify athletes with concussion," Dr. Balcer commented in an interview.
"A group of tests also helps add to clinical diagnosis of concussion immediately post injury by testing the brain’s many pathways that can be affected, including vision, cognition, and balance," she said.
"While no one test or group of tests can substitute for the fact that concussion is a clinical diagnosis, based on the judgment of the health care provider, trainer, parent, or athlete, having quick sideline tools that can be easily administered by laypeople adds an important element to how we identify concussions among youth athletes," Dr. Balcer observed. Young athletes are a particular group for which athletic trainers and physicians are not usually available on the sidelines.