title: Walking in fully immersive virtual environments: an evaluation of potential adverse effects in older adults and individuals with Parkinson's disease.
abstract: BACKGROUND
  Virtual reality (VR) has recently been explored as a tool for neurorehabilitation to enable individuals with Parkinson's disease (PD) to practice challenging skills in a safe environment. Current technological advances have enabled the use of affordable, fully immersive head-mounted displays (HMDs) for potential therapeutic applications. However, while previous studies have used HMDs in individuals with PD, these were only used for short bouts of walking. Clinical applications of VR for gait training would likely involve an extended exposure to the virtual environment, which has the potential to cause individuals with PD to experience simulator-related adverse effects due to their age or pathology. Thus, our objective was to evaluate the safety of using an HMD for longer bouts of walking in fully immersive VR for older adults and individuals with PD.
  
  
  METHODS
  Thirty-three participants (11 healthy young, 11 healthy older adults, and 11 individuals with PD) were recruited for this study. Participants walked for 20 min while viewing a virtual city scene through an HMD (Oculus Rift DK2). Safety was evaluated using the mini-BESTest, measures of center of pressure (CoP) excursion, and questionnaires addressing symptoms of simulator sickness (SSQ) and measures of stress and arousal.
  
  
  RESULTS
  Most participants successfully completed all trials without any discomfort. There were no significant changes for any of our groups in symptoms of simulator sickness or measures of static and dynamic balance after exposure to the virtual environment. Surprisingly, measures of stress decreased in all groups while the PD group also increased the level of arousal after exposure.
  
  
  CONCLUSIONS
  Older adults and individuals with PD were able to successfully use immersive VR during walking without adverse effects. This provides systematic evidence supporting the safety of immersive VR for gait training in these populations.
authors.affiliation: Division of Biokinesiology and Physical Therapy, University of Southern California, 1540 E. Alcazar St, CHP 155, Los Angeles, CA, 90033, USA.
authors.forename: Aram
authors.initials: A
authors.lastname: Kim
authors.affiliation: Division of Biokinesiology and Physical Therapy, University of Southern California, 1540 E. Alcazar St, CHP 155, Los Angeles, CA, 90033, USA.
authors.forename: Nora
authors.initials: N
authors.lastname: Darakjian
authors.affiliation: Division of Biokinesiology and Physical Therapy, University of Southern California, 1540 E. Alcazar St, CHP 155, Los Angeles, CA, 90033, USA. jmfinley@usc.edu.
authors.forename: James M
authors.initials: JM
authors.lastname: Finley
mesh_terms: D000328:Adult; D005081:Exercise Therapy / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000534:rehabilitation*; D011795:Surveys and Questionnaires; D063367:Virtual Reality Exposure Therapy / Q000295:instrumentation; D016138:Walking
keywords: Gait; Head-mounted display; Parkinson’s disease; Simulator sickness; Virtual reality