ALTERATIONS IN VISUAL PROCESSING AND ITS IMPACT ON UPRIGHT POSTURAL STABILITY IN ATHLETES FOLLOWING SPORT-RELATED CONCUSSION

Athletes are at risk of sustaining a concussion in all sports and at all competitive levels which may lead to balance impairments. Balance results from the integration of visual, vestibular, and somatosensory information. The underlying pathophysiology for balance impairments is not well understood and visuo-motor processing impairments and how these impairments contribute to balance in concussed athletes has not been reported. Objectives: (1) to investigate the influence of visual perturbation on upright postural stability and balance in athletes who have recently suffered a sports-related concussion, (2) to establish the test-retest reliability of a simple visuo-motor processing task. Design: A longitudinal, cohort design. Setting: University research laboratory. Subjects: Fourteen interscholastic, club, and intercollegiate athletes (8 males, 6 females, age 17.21±2.97 years, height 176.43±12.73cm, mass 75.55±22.76kg) participated. Seven subjects with acute concussions (injury) were matched to seven control subjects. Intervention(s): All subjects completed a simple visuo-motor processing task (SVMP), Sensory Organization Test (SOT), and modified Clinical Test of Sensory Interaction in Balance (mCTSIB). Each subject’s balance was tested under two visual testing conditions: (1) standard testing methods with normal visual fields, and (2) visual distraction through optical flow motion using a computer-generated optical flow pattern. Testing was done 24-48 hours and ten days following injury. The order of the testing was counterbalanced (standard protocol or visual distraction) and day of testing. Main Outcome Measures: Reaction time, accuracy, number of errors on SVMP; composite equilibrium score, sensory system preference on SOT; and mean center of gravity sway velocity on mCTSIB. Results: Significant impairments were noted on day 1 of testingcompared to day 10 for SVMP reaction time (day 1=496.18±52.82ms, day 10=439.01±20.62ms, F=4.72, p=0.01), and SOT composite equilibrium score standard (day 1=73.14±5.73, day 10=83.57±2.15, F=7.60, p\u3c0.001). Conclusion: Physiological changes occur immediately following concussions that affect the visual system, more specifically, visuo-motor processing. The SVMP task provides unique information about visuo-motor processing following a concussion that is not currently being assessed. Visuo-motor processing is correlated with upright balance and should be evaluated following a sports-related concussion