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Published on: February 19, 2017
Correlation of King-Devick Test and Helmet Impact Exposures Over a Youth Football Season
Jennifer R Maynard1,2, Jeffrey P Nadwodny3, Irvin S Haak4
1Department of Orthopedics, Division of Sports Medicine, Mayo Clinic, Jacksonville, Florida.
Background:
The cumulative effect of repetitive subconcussive head impacts on neurocognitive function during youth contact sports remains largely unknown. There is a paucity of literature evaluating cumulative helmet forces over a season and their correlation with preseason and postseason cognitive performance tasks such as the King-Devick test (KDT).
Hypothesis:
Higher helmet forces recorded throughout a 10-week, 10-game youth football season would correlate with slower performance on postseason KDT.
Study Design:
Prospective cohort study.
Level Of Evidence:
Level 3.
Methods:
A cohort of 58 youth football players (ages 9-13 years) underwent pre- and postseason KDT. Players wore SpeedFlex helmets (Riddell) fitted with InSite Impact Response System helmet accelerometers (Riddell) which recorded impacts of ≥15g. Head impacts were tallied over a season and assigned a score of 1, 2, or 3 based on magnitude of g forces. Suspected concussions were correlated with KDT times and recorded instances of head impact. Pre- and postseason KDT scores were compared.
Results:
During the season, 2013 head impacts were recorded. Median (range) total cumulative force score was 24 (5-476); 6 players sustained head impacts concerning for concussion, and 4 were clinically diagnosed with concussions. Overall, postseason KDT times improved compared with preseason, with a median (range) change of -4.8 seconds (-7.6, -1.1). Analysis showed no correlation between changes in KDT time and total cumulative force score over the season.
Conclusion:
KDT times in youth football players did not change significantly based on head impact exposure over a single youth football season; most players' KDT times improved from preseason to postseason.
Clinical Relevance:
Although our study did not show significant cognitive impact as measured by KDT over a single youth football season, the long-term effects of concussion on the immature brain and how it can impact cognitive development remains largely unknown and should be an area of ongoing study.
