95 - Comparing Performance on a Vestibular Virtual Environment Task that Involves Upper Extremity Reaching While Walking

Abstract Text:

Background:
Of the 453,919 traumatic brain injuries among service members reported since 2000, 82.3% were classified as mild traumatic brain injury (mTBI). Vestibular impairments are common after mTBI and can be associated with dizziness and postural instability. These symptoms can significantly affect quality of life and ability to return to duty. Vestibular Physical Therapy (VPT) is often recommended to address persistent postconcussive vestibular symptoms. VPT aims to decrease symptoms, increase functional tolerance, and improve quality of life. Use of virtual reality (VR) technologies in VPT have shown improved rehabilitation outcomes. At the National Intrepid Center of Excellence (NICoE) and the Naval Health Research Center (NHRC), the Computer Assisted Rehabilitation Environment (CAREN) system has been utilized in VPT. Although there are several benefits to the CAREN, its widespread use is limited due to its size and cost, as well as the need for an engineer to run and maintain the system. With recent advancements in head-mounted display (HMD) technologies, alternatives to the CAREN are possible. An augmented reality (AR-HMD) is mobile and relatively inexpensive. In AR, virtual elements are displayed over the real-world environment, so visual cues are still accessible to the user. The aim of this study is to determine how performance on a vestibular virtual environment (VE) task, carried out while walking, differs between a mobile AR-HMD system and the CAREN.

Methods:
Participants were recruited from San Diego, CA (NHRC) and Bethesda, MD (NICoE/Walter Reed National Military Medical Center). All were either active duty or retired service members between 18 and 55 years old, with normal or corrected vision, not significantly affected by motion sickness, and without musculoskeletal injuries that would affect gait. Participants were categorized into two groups: those with a history of a mTBI and those without a history of mTBI (control; CON). All participants completed Soccer Balls, a VE that requires the participant to reach with either hand to ‘hit’ the target ball, while walking at their preferred walking speed in three conditions: standard (STAN), static Stroop (SS), and dynamic Stroop (DS). STAN required the participant to try to ‘hit’ Soccer Balls as they approached from different locations in the virtual space. SS and DS required the participant to first scan the virtual space to find a color word with an incongruent text color, then select the matching colored ball from the four presented. The ball quartet was either directly in front of the participant (SS) or traveled towards the participant (DS). Performance, as measured by task accuracy (%), gait speed (m/s), cadence (strides/s), and stride length normalized to the participants’ height, was compared between systems using paired t tests (α=0.05).


Results:
There were 7 CON and 3 mTBI participants included in this preliminary analysis (total N =10). Average walking speed (N=10) was 0.98±0.08 m/s for both the CAREN and AR-HMD systems with similar walking speeds observed for both the CON (0.97±0.19m/s) and mTBI (1.00±0.0m/s) groups. Accuracy during the STAN condition was lower using the AR-HMD than the CAREN system (p=0.0021). No significant differences for any other condition were observed in accuracy, stride length, or cadence.

Conclusions:
Preliminary analyses indicate participant performance with the AR-HMD was not significantly different from the CAREN when completing a vestibular virtual environment task that involves reaching while walking with only lower accuracy during the STAN condition. Additional analyses will be conducted to examine any differences between participant groups and user experience feedback. We hope to expand on these results in our upcoming VPT pilot study.

Disclaimer: I am a military service member or employee of the U.S. Government. This work was prepared as part of my official duties. Title 17, U.S.C. §105 provides that copyright protection under this title is not available for any work of the U.S. Government. This work was supported by the Congressionally Directed Medical Research Program PH/TBI Research Program under work unit no. N1801 (FY16; Award#: CDMRPL-17-0-PT160118). The views expressed in this work are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense, nor the U.S. Government.

Keywords: Vestibular Physical Therapy, Rehabilitation, Gait, Virtual Reality, Augmented Reality