Introduction
Sport concussions have become a large area of study for physicians, athletic trainers, and other medical professionals in the past couple decades due to the increased popularity and participation in youth, high school, collegiate, professional, and recreational sports. The Center for Disease Control and Prevention (CDC) report that approximately 38 million children and 170 million adults participate in organized sports or physical activity each year (CDC, 2007).
A concussion or mild traumatic brain injury (TBI) is an acceleration-deceleration injury that occurs to the head causing an alteration in mental status. The Consensus Statement on Concussion in Sport defines a concussion as a “complex pathophysiological process affecting the brain, produced by traumatic biomechanical forces” (McCrory, Meeuwisse, Johnston, Dvorak, Aubrey, Molloy, & Cantu, 2008). A person with a concussion may exhibit: headache, nausea, vomiting, dizziness, balance problems, fatigue, difficulty sleeping, drowsiness, light sensitivity, noise sensitivity, blurred vision, and memory difficulty (McCrea, Guskiewicz, Marshall, Barr, Randolph, Cantu, Onate & Yang, 2003)
One of the main ways a clinician can assess a concussion is by evaluating balance and postural stability deficits. Literature has revealed that the areas of the brain affected most as a result of a mild head injury are responsible for equilibrium (Guskeiwicz, Riemann, Perrin, & Nashner, 1997). The most commonly used postural stability test in athletics is the Balance Error Scoring System (BESS). The BESS is an excellent test when assessing an athletes’ balance on the sidelines during a practice or game after a suspected concussion. However, various researchers and medical professionals believe that the BESS is subjective in nature and does not provide much objective findings that may detect the subtle postural stability deficiencies post-concussion. The present study was interested in examining and comparing the subjective findings from the BESS to the more objective findings of the Biodex Balance System (BBS). The objective of the BBS is to quantitatively determine a subjects’ sway, which will define the ability to maintain a stable vertical posture while on a stationary platform (Biodex Medical Systems, Inc., 2011).
Therefore, the purpose of this study was to validate the Biodex Balance System as an objective and reliable tool for concussion assessment. A second purpose of this study was to determine the relationship of the traditional BESS scores and the OSI while performing the BESS on the BBS. Specifically, the researcher aimed to answer the following questions:
(1) What is the test-retest reliability of the BESS on the BBS?
(2) What is the relationship between the BESS error scores and the OSI scores on the BBS?
Methods
Thirty healthy male and female subjects participated in this investigation. Each subject performed three separate trials of the BESS protocol on the BBS. Each trial was at least ten days apart to decrease the likelihood of a learning curve. The participants were video recorded from the front view at a 45-degree angle for optimal visual examination for detecting errors. An error was described as any deviation from the stance. The highest score for each stance is 10 errors; therefore the maximum score that can be given for the entire BESS protocol is 60. A qualified scorer evaluated all subjects on a later date, which allowed for repeated and precise scoring. Along with counting the errors, the overall sway index (OSI) was recorded on the BBS. Upon completion of the third testing session, results were analyzed to determine the test-retest reliability of the BESS on the BBS and determine if any significance was found between the BESS error scores and the OSI scores.
Results
Pearson correlation analyses demonstrated there were moderate significant correlations between OSI 1 to OSI 2 (r = 0.589**), OSI 2 to OSI 3 (r = 0.648**), and OSI 1 to OSI 3 (r = 0.690**) at the p = .01 level. Significant correlations between BESS 1 to BESS 2 (r = 0.716**), BESS 2 to BESS 3 (r = 0.709**), and BESS 1 to BESS 3 (r = 0.900**). No significant correlation was found between BESS 1 to OSI 1 (r = 0.342), low to moderate significant correlation between BESS 2 to OSI 2 (r = 0.412* significant at p = .05 level) and moderate significant correlation between BESS 3 to OSI 3 (r = 0.603** significant at the p = .01 level)
Conclusions
Our results revealed that the BESS showed much better correlations than did the BBS. However, we feel that the results found in the present study are inconclusive and further research is needed to determine if the BBS is a reliable tool for detecting postural stability deficits following a concussion. From the results found in this study it seems as if the BESS should continue to be utilized as the `gold standard’ when evaluating the balance of concussed athletes, however, clinicians should be wary of the possible practice affects associated with the BESS test.