Quantification of postural control deficits in patients with recent concussion: An inertial-sensor based approach.

BACKGROUND The aim of this study was to quantify postural control ability in a group with concussion compared with a healthy control group. METHOD Fifteen concussion patients (4 females, 11 males) and a group of fifteen age- and sex-matched controls were recruited. Participants were tested during the performance of the three stance variants (bilateral, tandem and unilateral) of the balance error scoring system standing on a force place, while wearing an inertial measurement unit placed at the posterior aspect of the sacrum. FINDINGS The area of postural sway was computed using the force-plate and the '95% ellipsoid volume of sway' was computed from the accelerometer data. Concussed patients exhibited increased sway area (1513mm2 [95% CI: 935 to 2091mm2] vs 646mm2 [95% CI: 519 to 772mm2]; p=0.02) and sway volume (9.46m3s-6 [95% CI: 8.02 to 19.94m3s-6] vs 2.68m3s-6 [95% CI: 1.81 to 3.55m3s-6]; p=0.01) in the bilateral stance position of the balance error scoring system. The sway volume metric also had excellent accuracy in identifying task 'errors' (tandem stance: 91% accuracy [95% CI: 85-96%], p<0.001; unilateral stance: 91% accuracy [95% CI: 86-96%], p<0.001). INTERPRETATION Individuals with concussion display increased postural sway during bilateral stance. The sway volume that was calculated from the accelerometer data not only differentiated a group with concussion from a healthy control group, but successfully identified when task errors had occurred. This may be of value in the development of a pitch-side assessment system for concussion.