Initial Concussion Presentation Does Not Predict Gait Initiation Performance

Abstract

Many concussion grading systems utilize the presence of loss of consciousness (LOC) and/or post-traumatic amnesia (PTA) as hallmarks of injury severity. However, evidence supporting this inclusion criteria is limited. Previous investigations have studied long term outcome, however initial postural control has not been studied. Gait initiation (GI) is a sensitive postural control measure in a wide range of individuals with central neurophysiological deficits. PURPOSE: To determine the influence of LOC/PTA on GI performance in subjects within 24 hours post-concussion. METHODS: 25 subjects (19.6 ± 1.6 years old, 1.76 ± 0.16m, 78.4 ± 27.9kg) were divided into 2 groups; those who experienced (n=9) or did not experience (n=16) LOC/PTA. Presence of LOC/PTA was documented by the athletic trainer who initially treated the injury. All subjects performed 5 trials of GI on the day following the concussion. GI was performed utilizing three forceplates (AMTI, Watertown, MA) and kinetic data was sampled at 1,000 Hz. Dependent variables included the posterior and lateral displacement of the center of pressure (COP) during the anticipatory postural phase (S1) of GI as well as initial step length and velocity and were compared using a one-way ANOVA. RESULTS: There were no differences between LOC/PTA and no LOC/PTA groups for age, height, or weight, but the LOC/PTA group had a history of significantly more concussions (1.9 ± 1.5 and 0.6 ± 1.3 respectively, p = 0.03). There were no differences between the LOC/PTA and no LOC/PTA groups in the S1 COP displacement in either the posterior (2.3 ± 1.8cm and 2.5 ± 2.1cm respectively, P = 0.76) or lateral (2.9 ± 1.5cm and 2.9 ± 2.3cm respectively, P = 0.94) directions. Additionally, no differences were noted in initial step length (0.56 ± 0.12m and 0.63 ± 0.06m respectively, P = 0.07) or initial step velocity (0.56 ± 0.22m/s and 0.66 ± 0.12m/s respectively, P = 0.13). CONCLUSION: Previous studies have identified no differences in overall outcome between subjects who suffer LOC or PTA, however this is the first report to suggest that there are no differences in postural control within 24 hours post concussion. While on-field presentation certainly influences acute care, this finding supports previous reports indicating an apparent lack of residual impairments as a result of LOC or PTA at the time of injury.