Background: Concussion management practices are important for athlete safety. Baseline testing provides a benchmark to which post-injury assessments are compared. Yet few neurophysical concussion assessment studies have examined learned response. The Balance Error Scoring System (BESS) measures postural stability through 6 conditions by counting the errors committed during each condition. In a study examining the performance of high school-aged athletes on the BESS, the learned response extinguished in 3 weeks. However, this phenomenon has not been studied in the college-aged population.
Hypothesis: College-aged adults performing the BESS will have a learned response at 1 and 2 weeks but would have no change from baseline at or after 3 weeks, as found previously in high school-aged subjects.
Study design: Randomized controlled clinical trial.
Methods: Three groups of college-aged adults ages 18 to 26 years were tested using the BESS at scheduled intervals. Each subject was randomly assigned into 1 of 3 groups to determine learned response at weeks 1, 2, and 4. Changes in pretest and posttest BESS scores were compared using the paired t test for each group at week 4 and other intervals. Differences among groups were compared using analysis of variance for means or the chi-square test for proportions.
Results: After 4 weeks, participants exhibited a mean (95% confidence interval) change from pretest baseline of -2.30 (-4.75, 0.16) in the control group (P = 0.065), -3.13 (-4.84, -1.41) in Group 1 (P = 0.001), and -2.57 (-5.28, 0.15) in Group 2 (P = 0.063). There were no statistically significant differences between the 3 groups for week 4 BESS score (P = 0.291) or changes from baseline to week 4 BESS scores (P = 0.868). Overall, participant score changes from baseline to the 4-week follow-up still showed a statistically significant or close to significant reduction across the 3 groups, indicating the learned response did not extinguish after 4 weeks.
Conclusion: Repeated BESS testing results in a learned effect in college-aged adults did not extinguish after 4 weeks. These results question the ability of the BESS to assess an athlete's balance deficits following a concussion.
Clinical relevance: Given learned response did not extinguish in this sample and the BESS has a minimal detectable change/reliable change index of 7 or greater, the effectiveness of the BESS to assess balance may be limited.
Keywords: concussion; learned behavior; practice effect; traumatic brain injury.