Effects of subconcussive head impacts on concussion symptoms, clinical reaction time, and oculomotor function in men's lacrosse players

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University of Delaware
Context: To clinicians, researchers, and athletes alike, the recent evidence suggesting the detrimental effects of subconcussive head impacts (SCHI) in collision sport athletes is alarming. The sport of lacrosse like football, ice hockey, and soccer, has a high-risk for sport-related concussions (SRC). However, there is paucity in research examining male lacrosse players despite the high risk for SRC and the opportunity for repeated SCHI to the helmet during competition. Unlike American football, unique to the sport of lacrosse is the fact that they are often asked to play games with minimal rest periods in between which provides for a chance to study SCHI in this population during a truncated week of competition. Objective: The primary goal of this study was to examine if SCHI had an effect on concussion-related symptoms, clinical reaction time, and oculomotor function in men's lacrosse players (MLAX) in a shortened time frame between two regularly scheduled games (Wednesday and Saturday). Design: Two-group pretest-posttest design. Setting: Quiet, climate-controlled research laboratory. Patients or Other Participants: Subjects consisted of 18 men's (height=181.3±6.6cm, mass=86.3±6.4kg, age=20.6±1.3yrs.) and 13 women's (height=168.6±6.0cm, mass=61.3±4.6kg, age=19.7±1.1yrs.) lacrosse players from an NCAA Division-I institution. The non-helmeted female lacrosse players (WLAX) were chosen to serve as controls. MLAX consisted of selected individuals who were expected to see a considerable amount of playing time in games. Interventions: Each subject was tested on 3 separate occasions (baseline [BASE], post-game 1 [POST], and prior to game 2 [PRIOR]). Games 1 and 2 were separated by 2 days. Testing included a concussion symptom checklist (SXC), clinical reaction time (CRTA), and the King-Devick (K-D Test(TM)) test of oculomotor function. Main Outcome Measures: SCHI were counted using videotape replays of all lacrosse games. The total number of symptoms was determined at each test session. The 3 CRT trials (time in msec.) were averaged. The KD test yielded both a total time (sec.) to completion score and total number of errors committed. Analysis of covariance statistical techniques was used to determine if differences existed between BASE and POST, as well as BASE and PRIOR across all dependent measures between MLAX and WLAX. Results: The SCHI ranged from 0-4 for MLAX and 0-3 for WLAX. In both groups across BASE to POST and BASE to PRIOR comparisons for all dependent variables (SXC, CRTA, KD time, and KD error) none were found to be statistically significant at p=0.05. CRTA BASE to PRIOR was trending towards significance with F=3.812 and p=0.061. Conclusions: Interestingly the number of SCHI in the MLAX group was well below what we had anticipated, and quite different from their helmeted counterparts in ice hockey and football. It was somewhat alarming to learn that 7 of the 13 WLAX experienced SCHI to their un-helmeted head during competition. Despite the aggressive and full-collision nature of the MLAX game, our study has determined that there are no detrimental effects on several measures of concussion following the small number of SCHI during competitive games.