Chronic impairments of static postural stability associated with history of concussion.

Postural stability deficits are commonly observed in cases of concussion. However, the objective duration in which impairments of standing postural stability remain following a concussion is often inconclusive. The present study was conducted to determine if prior history of concussion is associated with deficits in postural stability beyond the clinical determination of recovery. It was hypothesized that concussion history would be associated with decreases in static stability compared to individuals that have never sustained a concussion. Fifty-four healthy adults were recruited based on whether they reported sustaining one or more prior concussions (n = 27) or no history of concussion (n = 27). Participants were instructed to stand on a force platform to track center-of-pressure (CoP) during standing for thirty seconds under four conditions based on stance and number of tasks: (1) bipedal, single-task, (2) bipedal, dual-task, (3) unipedal, single-task, and (4) unipedal, dual-task. Results revealed that individuals with a history of concussion demonstrate significantly reduced postural stability under dual-task conditions as evidenced by increases in average displacements and elliptical area of postural sway as well as reductions in CoP sample entropy. However, there were no significant differences in CoP displacement or elliptical area between groups under single task conditions. Overall, these findings indicate that concussion is associated with impairments of maintaining standing postural stability that remain evident approximately 7 years following clinical resolution of the initial injury. The exacerbation of these impairments under dual-task conditions indicate that concussion can result in a reduced capacity to allocate proper attention resources to multiple concurrent objectives.