A portable virtual reality balance device to assess mild traumatic brain injury symptoms A pilot validation study

Mild traumatic brain injury (mTBI) following a head impact or blast exposure can cause diffuse injury to the brain, which can affect sensorimotor, cognitive, and emotional processes. Among the most common sensorimotor symptoms of mTBI is balance impairment. A commonly used assessments of balance following mTBI is the sensory organization test (SOT). This test has shown that postural deficits following head injury may be due to visual-vestibular processing issues, but it is less sensitive to unremitting symptoms that do not spontaneously resolve within a week. Our current project involves demonstrating validity and reliability of a novel low-cost, portable virtual reality-based balance screening device that employs established principles of sensorimotor reweighting and visual-vestibular integration. The goal is to determine if it can replace existing tools that are either prohibitively expensive or lack reliability or sensitivity. Methods: Healthy adults with no known musculoskeletal or neurological injury (n=27; 17 males, 10 females; 22.1 +/- 3.9 years) were tested to establish healthy norms. Individuals with mTBI (n=8; 4 males, 4 females; 20.0 +/- 1.7 years) were compared to the healthy norms. The new VR-based balance assessment system consists of a Wii balance board (WBB), a large screen television, and a custom-designed software user interface used to collect and process data. Subjects performed six upright postural tasks (three visual conditions either standing directly on the WBB or on foam placed on the WBB). Subjects viewed a virtual reality scene displayed on a 60" television. The three visual conditions were Static Scene, Dark Scene, and Dynamic Scene (Roll at 60 deg/s). The WBB recorded COP at 100Hz for 30 sec. Dependent variables included COP velocity, root mean square, and sway area. Subjects also performed the sensory organization test (SOT), which can be used as criterion-measures for intraclass correlations with the new device. Results: Preliminary data on healthy subjects validates effectiveness of the device to reduce postural stability as sensory input reliability and availability decreases. Additionally, our results reveal that individuals with mTBI have significantly worse balance scores on the new VR-device (p<0.001). This highlights its sensitivity to balance disturbance even if when testing a small sample. Comparison of the new device to SOT shows good criterion validity with ROC curves revealing sensitivity/specificity equal or higher than the SOT. COP sway area, velocity, and standard deviation of medial-lateral and anterior-posterior sway were all sensitive dependent variables. In conclusion, this study helps demonstrate that our new VR-based assessment tool is a valid measure fur detecting balance related changes in neurologically impaired individuals and can potentially replace much more expensive equipment. Using postural control as an outcome measure of brain injury may help improve identification of individuals with sub-acute symptoms which may he used to guide rehabilitation and clinical decision making.