Effects of Virtual Walking on Chronic Pain and Psychological Distress for Individuals With Severe Mobility Impairment

Background: Severe mobility impairment (SMI) negatively impacts lifespan and quality of life, especially through chronic pain and emotional issues such as depressive symptoms. Researchers have developed treatments including pharmacological interventions, physical activities, complementary and alternative medicine, and psychological treatment to treat chronic pain and emotional issues. However, these approaches have limitations. Virtual walking interventions utilize arm-swing locomotion to create the illusion of walking, allowing individuals to experience walking in virtual natural scenes. These interventions have shown feasibility and preliminary effects on mood and pain reduction in people with spinal cord injury. However, prior work varies in locomotion design (e.g., passive observing, trigger-based, or arm-swing), dosage (session length and total dose), and a few studies incorporate objective biomarkers like EEG to test neurological mechanisms.

Thus, this study aims to examine the effects of virtual walking on chronic pain and psychological distress and to explore the neurological mechanisms of virtual walking using the resting-state and task-based EEG.

Design:

This study will be a single-blind, two-arm, parallel-group pilot randomized controlled trial (RCT).

Participants and Subgroup Stratification:

Forty-eight participants experiencing chronic pain will be recruited from the Hong Kong Polytechnic University. At baseline, all recruited participants will be screened for neuropathic pain using the Douleur Neuropathique 4 Questions (DN4) questionnaire. Participants who score ≥4 will be classified into a neuropathic pain subgroup. To facilitate mechanism-based subgroup analysis in the EEG data processing, only participants in this specific subgroup will undergo an additional Quantitative Sensory Testing (QST, Medoc) at baseline. Besides, another healthy control group will be added to provide a normative reference for exploratory mechanistic analyses.

Interventions:

Participants will be randomly assigned to one of two arms:

• Virtual walking group: Participants will engage in an arm-swing virtual walking intervention. This consists of a 13-minute session daily for 10 days.
• Control group: Participants will receive a time-matched passive video observing control, watching walking videos for 13 minutes daily for 10 days.

Instruments: Validated questionnaires, 64-channel EEG, and HRV monitoring.

Qualitative Evaluation:

Following the completion of the intervention, qualitative semi-structured interviews will be conducted with participants to explore their perceived effects, strengths, and limitations of the intervention.

Inclusion criteria

• People with SMI (the operational definition of SMI is inability to walk 4 meters in less than 10 seconds, or self-, proxy-, or medical record reported inability to walk across a small room, or dependence on a walking aid during walking for more than 6 months (Pahor et al., 2014));
• At least 6 months post-injury and in stable status;
• Persistent chronic pain (more than 3 months) with a reported Numerical Pain Rating Scale ≥ 4 (Villiger et al., 2017);
• Had no changes in their pain medication regimen in the past month;
• Able to communicate in Cantonese and to provide informed consent.

Exclusion criteria

• Have severe cognitive impairment (a score < 6 on the Abbreviated Mental Test (Chu et al., 1995));
• Had a history of moderate to severe brain injury;
• Have neurological disorders which affect brain function (i.e., stroke, Alzheimer's, Parkinson's, epilepsy) that may confound EEG measures;
• Have a severe psychiatric disorder (schizophrenia or major depression);
• Have an upper limb condition influencing the use of VR (e.g., arthritis or upper limb amputation).