Overground and Virtual Reality Gait Speed Are Associated With Atypical Symptom Reporting in Active Duty Service Members With a History of Mild to Moderate Traumatic Brain Injury.

OBJECTIVE: Physical therapy following traumatic brain injury (TBI) can be negatively impacted by psychological symptoms, atypical symptom reporting, and response bias. We examined rates of Symptom Validity Test (SVT) failure in active duty military service members with a history of mild-moderate TBI and its impact on gait speed. SETTING: Intensive Outpatient Program at the National Intrepid Center of Excellence at Walter Reed National Military Medical Center. PARTICIPANTS: Participants were 84 active duty service members with a history of mild-moderate TBI classified as SVT pass ( n = 49) or SVT fail ( n = 35). DESIGN: Retrospective study. MAIN MEASURES: Overground preferred and fast walking speed as well as Computer Assisted Rehabilitation Environment (CAREN) gait speed were recorded. Participants completed the Neurobehavioral Symptom Inventory and the Validity-10 was used to assign patients into the SVT pass and SVT fail groups. Gait speed metrics were compared across these groups and test operating characteristics were calculated. RESULTS: Approximately 42% of the sample was classified into the SVT fail group. All 3 gait speed measures were significantly slower in the SVT fail group than in the SVT pass group ( P s < .001, d s = 0.60-0.80). Gait speed cutoffs for screeners or indicators of atypical reporting were identified. CONCLUSIONS: The potential for response bias is a critical area for the clinician to consider when conducting physical therapy evaluations. Participants in the SVT fail group had slower walking speed on all 3 measures assessed. Several useful cutoffs were identified to serve as screeners or indicators of SVT failure, though these preliminary findings have limitations and need to be replicated.

Examining the Relationship Between Conventional Outcomes and Immersive Balance Task Performance in Service Members With Mild Traumatic Brain Injury.

INTRODUCTION: Mild traumatic brain injury (mTBI) is associated with significant financial cost and reduced military readiness and impacts quality of life for active duty service members (SMs). Post-concussive symptoms can include vestibular impairments, such as chronic dizziness and postural instability, which can be compounded by psychological comorbidities like PTSD. Comprehensive vestibular evaluations are required to assess symptoms and guide clinical decision-making. At the National Intrepid Center of Excellence (NICoE), in addition to traditional vestibular assessments, clinicians can also leverage virtual environments (VEs) in the Computer-Assisted Rehabilitation Environment (CAREN) to further evaluate balance. The objective of this study was to examine the relationship between conventional outcomes and VE performance on immersive balance tasks in the CAREN, determine whether VE performance could predict conventional outcomes, and explore the impact of PTSD. MATERIALS AND METHODS: This retrospective analysis included 112 SMs from the NICoE Intensive Outpatient Program who provided informed consent for their clinical data to be used for research purposes. All had a history of mTBI, underwent vestibular evaluations, and completed immersive balance tasks on the CAREN. Conventional outcomes included the Sensory Organization Test (SOT), Functional Gait Assessment (FGA), Activities Balance Confidence (ABC) Scale, and Dizziness Handicap Inventory (DHI). The PTSD Checklist-Military Version was added to account for behavioral symptoms. Computer-Assisted Rehabilitation Environment outcomes included total time to complete the Balance Cubes VE, with the platform static (BC-Static) and with random platform motion (BC-PM) as well as composite scores for the Shark Hunt VE, with (SH-Recall) and without a recall task (SH-Standard). Statistical analyses included independent t-tests to determine group differences, Pearson's correlations to examine relationships between conventional outcomes and VE performance, and binary logistic regressions to determine if VE performance predicted conventional outcomes based on clinically relevant cutoffs. RESULTS: SMs who took less time to complete BC-Static had better overall balance, indicated by higher ABC, SOT, and FGA scores (P <.001). Those with greater self-reported dizziness, higher DHI scores, took longer to complete BC-Static (P < .05). FGA and SOT, objective gait and balance, were similarly correlated to BC-PM performance (P <.001). SMs with higher SOT scores, better balance, also tended to have higher SH-Standard scores (P <.1). SMs, who were above normative SOT, FGA, and ABC cutoffs, completed BC-Static significantly faster than those below (P <.05). This remained true for BC-PM but was only significant for SOT (P = .004). Performance on BC-Static, BC-PM, and SH-Standard was significant predictors of SOT score. For SMs with comorbid mTBI and PTSD, increased functional disability was observed in conventional outcomes and diminished VE performance was noted. CONCLUSION: Objective balance and gait, SOT and FGA, demonstrated the strongest relationships to immersive VE performance in the CAREN. Our findings suggest that these immersive balance tasks may be effective as an adjunct assessment to examine balance. Future work will focus on moving these VEs from the CAREN to a portable system, which could be more readily utilized in a variety of clinical settings, increasing accessibility.