Timing of Concussion Diagnosis Is Related to Head Impact Exposure Prior to Injury

Concussions are commonly undiagnosed in an athletic environment because the post-injury signs and symptoms may be mild, masked by the subject, or unrecognized. This study compares measures of head impact frequency, location and kinematic response prior to cases of immediate and delayed concussion diagnosis

Head Impact Exposure Sustained by Football Players on Days of Diagnosed Concussion

This study compares the frequency and severity of head impacts sustained by football players on days with and without diagnosed concussion and to identify the sensitivity and specificity of single impact severity measures to diagnosed injury

Timing of Concussion Diagnosis Is Related to Head Impact Exposure Prior to Injury

PURPOSE: Concussions are commonly undiagnosed in an athletic environment because the post-injury signs and symptoms may be mild, masked by the subject, or unrecognized. This study compares measures of head impact frequency, location and kinematic response prior to cases of immediate and delayed concussion diagnosis. METHODS: Football players from eight collegiate and six high school teams wore instrumented helmets during play (n=1,208), of which ninety-five were diagnosed with concussion (105 total cases). Acceleration data recorded by the instrumented helmets was reduced to five kinematic metrics: peak linear and rotational acceleration, GSI, HIC(15), and change in head velocity (Δv). Additionally, each impact was assigned to one of four general location regions (Front, Back, Side, and Top), and the number of impacts sustained prior to injury was calculated over two time periods (one and seven days). RESULTS: All head kinematic measures associated with injury, except peak rotational acceleration (p = 0.284), were significantly higher for cases of immediate diagnosis than delayed diagnosis (p<0.05). Players with delayed diagnosis sustained a significantly higher number of head impacts on the day of injury (32.9 ±24.9; p < 0.001) and within seven days of injury (69.7 ±43.3; p = 0.006) than players with immediate diagnosis (16.5 ±15.1 and 50.2 ±43.6). Impacts associated with concussion occurred most frequently to the Front of the head (46%) followed by the Top (25%), Side (16%), and Back (13%) with the number of impacts by location independent of temporal diagnosis (χ(2)(3) = 4.72; p = 0.19). CONCLUSIONS: Concussions diagnosed immediately after an impact event are associated with the highest kinematic measures, while those characterized by delayed diagnosis are preceded by a higher number of impacts