Abstract
Objective: The purpose of this study was to determine if exercise-induced vision dysfunction (reduced performance and/or symptom exacerbation on a post-exercise King-Devick (KD) test) in adolescents early after sport-related concussion was associated with increased risk of persistent post-concussive symptoms (PPCS, recovery>28 days). By using the King-Devick (KD) test after exercise rather than at rest, we hypothesized that concussed adolescents with exercise-induced vision dysfunction would be more likely to develop PPCS.
Design: Secondary analysis of data from a multi-center randomized clinical trial comparing KD test performance before and after the Buffalo Concussion Treadmill Test in adolescents within 10 days of concussion who were randomized to aerobic exercise or placebo stretching program.
Setting: Three university-associated sports medicine clinical programs.
Participants: 99 adolescents with sport-related concussion (Exercise Group: n=50, 15.3±1 y/o, 60% M, 22% with PPCS; Stretching Group: n=49, 15.9±1 y/o, 65% M, 35% with PPCS) tested a mean of 6±2 days from injury.
Independent Variable: KD performed immediately before and 2 minutes after Buffalo Concussion Treadmill Test.
Main Outcome Measure: Persistent Post-Concussion Symptoms
Results: Adolescents with exercise-induced vision dysfunction developed PPCS at a significantly greater rate when compared with adolescents without exercise-induced vision dysfunction (71% vs 34%, p<0.001). Exercise-induced vision dysfunction corresponded to a relative risk of 2.11 for developing PPCS.
Conclusion: Adolescents with exercise-induced vision dysfunction had a greater relative risk of developing PPCS compared to those without.
Summary Points:
- Adolescent athletes identified with exercise-induced vision dysfunction within 10 days of sport-related concussion had a greater than 2-fold risk of developing PPCS than adolescents with the normal learning effect on repeat KD testing.