Table 1 Overview of Study Design, Population, Health Outcomes, and Feasibility of Virtual Walking Interventions

(Eick et al.²⁰); USA;

Pilot experiment;

I: n = 3,

C: n = 5;

Rehabilitation Clinic

Paraplegia/Able-bodied;

I: 29.0 (3.6),

C: 31.6 (7.8);

Wheelchair

NR

• Cerebral blood flow (fMRI): During VW process, an activation in the bilateral somatosensory cortex and paracentral lobule in paraplegia patient^a

Recruitment: NR;

Adherence: 100%;

Satisfaction: NR;

Drop-out: 0

(Mollà-Casanova et al.¹); Spain

Pilot randomized control trial;

I: n = 6,

C: n = 6;

Hospital

Incomplete spinal cord injury;

Total: 52.0 (14.7);

Wheelchair

• Neuropathic Pain (Brief Pain Inventory): After intervention, no significant change in pain severity and interference in both groups;

• Physical Function: 1) Muscle Strength: After intervention, improvements in tibialis anterior mean strength^a (95%CI = −56.29 to −2.02, Cohen’s d = −0.51) and maximum strength in intervention group^a (95%CI = −60.67 to −2.90, Cohen’s d = −0.18). 2) Walking Performance: After intervention, walking speed improved^a (95%CI = 0.90 to 6.00, Cohen’s d = 0.52) in the 10-Meter Walk Test, walking ability improved^a (95%CI = −2.51 to −0.159, Cohen’s d = 0.13) in the Walking Index for Spinal Cord Injury in intervention group

NR

Recruitment: 80%

Adherence: All participants completed 80% of intervention;

Satisfaction: 91.67% of participants would be willing to undergo the intervention again;

Drop-out: 0

(Özkul et al.²³); Turkey

Randomized control crossover trial;

I1: n = 12,

I2: n = 12;

Hospital

Spinal cord injury;

Total: 32.3 (13.0);

Wheelchair

• Neuropathic pain: 1) Pain severity (Visual Analog Scale): After intervention, daily post-treatment pain intensity decreased by 19.8–26.8%^a in both groups, no significant changes in minimal, maximal, and average pain intensity in the intervention group. 2) Pain quality (Numerical Pain Scale): In the intervention group, sharpness (95%CI = 0.13 to 0.95, Cohen’s d = 0.16), hotness (95% CI = 0.01 to 0.83, Cohen’s d = 0.18), unpleasantness (95% CI = 0.02 to 1.23, Cohen’s d = 0.18), and depth (95% CI = 0.01 to 0.83, Cohen’s d = 0.17) improved^a. 3) Pain interference (Brief Pain Inventory): After intervention, improvement in pain on “ability to get around”^a (95%CI = 0.04 to 0.12, Cohen’s d = 0.18)

NR

Recruitment: NR

Satisfaction: NR

Adherence: NR;

Drop-out: 7.69%

(Gustin et al.¹⁷) USA

One group pre-post study;

I: n = 7;

Home

Spinal cord injury;

I: 45.1 (15.4);

Wheelchair

• Neuropathic pain: 1) Pain intensity: Average pain reduced post-intervention in Visual Analog Scale (Cohen’s d = 0.50) and Numerical Rating Scale^a (Cohen’s d = 0.46). 2) Pain-Related Disability (Pain Disability Index): No significant change. 3) Pain interference (Numerical Rating Scale) and severity (Numerical Pain Scale): Marginal decrease in pain interference and severity (p = 0.053, 0.052)

• Thalamic γ-aminobutyric-acid (Magnetic resonance spectroscopy): Decreased after intervention^a (ES = −0.72), but this change was not significant related to pain intensity

Recruitment: NR;

Satisfaction: NR;

Adherence: NR;

Drop-out: 0

(Jordan et al.²¹); USA

One group pre-post study;

Study 1: n = 35;

Lit room

Spinal cord injury;

I: 47.5 (9.4);

Wheelchair

• Neuropathic Pain (10 Numeric Rating Scale): 1) Decrease in at-level pain in VW condition compared with virtual wheeling condition^a. 2) No significant interaction was found between treatment and pain location

NR

Recruitment: NR;

Satisfaction: NR;

Adherence: All;

Drop-out: 0

(Landmann et al.²²); Switzerland

Feasibility study;

I: n = 4;

Paraplegia center

Spinal cord injury;

Total: 41.5 (15.7);

Wheelchair

• Neuropathic Pain: 1) Pain severity (Visual Analog Scale): 1 had a 31 mm reduction, while 3 experienced mild increases (1−7 mm). 2) Grade of chronification of pain (Mainz Pain Staging System): Decreased (2/3−0). 3) Pain intensity (Graded Chronic Pain Scale): 2 not change, 1 increased to grade 3 and 1 decreased to grade 3;

•Psychosocial (Depression, Anxiety, and Stress Scale): 1) Anxiety: Reduction (n = 1). 2) Depression: Clinical reduction (n = 1). 3) Stress: Reduction (n = 1);

•Catastrophic thinking (Pain Catastrophizing Scale): Decreased (n = 3);

•General well-being (Spinal Cord Injury Quality of Life Basic Data Set): No significant change

NR

Recruitment: NR;

Satisfaction: Moderate satisfaction (64–93.5)/100 score;

Adherence: All;

Drop-out: 0

(López-Carballo et al. 2018); Spain¹⁴

One group pre-post study;

I: n = 23;

Hospital

Lower limb neuropathic pain;

I: 48.17 (14.1);

Walk

• Neuropathic Pain (Visual Analog Scale): 69.5% of participants improved in average global pain post-treatment^a (Cohen’s d = 0.27)

NR

Recruitment: NR;

Satisfaction: NR;

Adherence: NR;

Drop-out: NR

Controlled experimental study;

I1: n = 14,

I2: n = 14;

Lower limb neuropathic pain;

I1: 53.14 (14.3),

I2: 52.57 (16.3)

• Neuropathic Pain (Brief Pain Inventory): Improvement in both computer and mirror + projector group post-treatment^a (Cohen’s d = 0.64, 0.47, respectively)

NR

(Richardson et al.²⁴); USA

Randomized control trial;

I: n = 30,

C: n = 29;

Lit room

Spinal cord injury;

I: 47.3 (12.0),

C: 43.0 (11.8);

Walk

• Neuropathic Pain: 1) Numerical Rating Scale: Decreased in VW group^a, no significant difference between-group. 2) Numerical Pain Scale: Pain symptoms reduced in cold, deep and skin sensitivity in VW compared to control^a (Cohen’s d = 0.97, 0.98, 0.98, respectively)

•Pain unpleasantness (Numerical Pain Scale): Reduction in VW compared to virtual wheeling group^a (Cohen’s d = 0.99)

NR

Recruitment:98.3%;

Adherence: 100%;

Satisfaction: NR;

Drop-out: 0

(Roosink et al.²⁵); Canada

One group pre-post study;

I: n = 9;

NR

Spinal cord injury;

I: 53.0 (13.9);

Wheelchair: 6, walk: 3

• Pain intensity: No significant change

NR

Recruitment: NR;

Adherence: NR;

Satisfaction: Positive interaction with the avatar;

Drop-out: NR

(Soler et al.²); Spain

Controlled experimental study;

I: n = 65,

C: n = 65;

Hospital

Spinal cord injury;

I: 49.0 (14.9),

C: 48.0 (14.6);

Wheelchair

• Neuropathic Pain (Neuropathic Pain Symptom Inventory): 1) Improvement in VW group compared to control group post-treatment^a (Cohen’s d = 0.20). 2) Improvements in pain types: burning (Cohen’s d = 0.20), squeezing (Cohen’s d = 0.14), electric shocks (Cohen’s d = 0.22), stabbing (Cohen’s d = 0.20), pain from touch (Cohen’s d = 0.18), pins and needles (Cohen’s d = 0.08), and tingling (Cohen’s d = 0.22) in tDCS+VW group^a

•Depression (Patient Health Questionnaire-9): Improved in tDSC+VW group post-treatment^a (Cohen’s d = 0.30)

NR

Recruitment: 83.33%;

Adherence: 97.69%;

Satisfaction: NR;

Drop-out: 2.31%

(Trost et al.¹⁶); Australia

Controlled experimental study;

I: n = 17,

C: n = 10;

Home

Spinal cord injury;

Total: 42.5 (12.4);

Wheelchair

• Neuropathic Pain: Reduction in pain intensity (Numerical Rating Scale), neuropathic pain (Numerical Pain Scale) and pain-related activity interference (Numerical Rating Scale) in interaction group post-intervention^a (Cohen’s d = 0.31, 0.34, 0.18, respectively)

•Mood and affect (Positive and Negative Affect Schedule): Improved in interactive groups post-treatment^a (Cohen’s d = −0.16);

•Depression (Patient Health Questionnaire-9): Decreased in both groups^a (Cohen’s d = 0.13, 0.10, respectively)

NR

Recruitment: NR;

Adherence and Satisfaction: Not report difficulty completing the virtual reality protocol;

Drop-out: NR

(Villiger et al.²⁶); Switzerland

One group pre-post study;

I: n = 12;

Home

Incomplete spinal cord injury;

I: 60.0 (10.2);

Wheelchair

• Physical Function: 1) Lower limb muscle strength (Lower Extremity Motor Score): Improved post-intervention^a. 2) Balance (Berg Balance Scale): Improved post-intervention^a. 3) Functional mobility (Timed Up and Go): Improved post-intervention, maintained at follow-up^a. 4) No significant effects on walking speed/distance (10 m walking test) and mobility (Walking Index for Spinal Cord Injury II) post-treatment

NR

Recruitment: NR;

Satisfaction: NR;

Acceptance: Training was well accepted by the patients;

Drop-out: NR

(Yilmaz et al.²⁷); Turkey

Randomized control trial;

I: n = 23,

C: n = 23;

Physiotherapy Clinic

Non-specific lower back pain;

I: 42.3 (10.9),

C: 52.8 (11.5);

Walk

• Pain (Visual Analog Scale): Decreased in VW group compared to control group post-treatment^a (Cohen’s d = 0.28);

•Physical Function: 1) Functional mobility (Timed-up and go Test, 6-Minute Walk Test): Improved in VW group compared to control group post-treatment^a (Cohen’s d = 0.77, 0.72, respectively). 2) Balance (Single leg balance test): No significant difference between-group;

• Fear of movement (TAMPA Kinesiophobia Scale): Decreased in VW compared to control group post-treatment^a (Cohen’s d = 0.82);

• Health-related quality of life (Nottingham Health Profile): No significant difference between-group

NR

Recruitment: 85.19%;

Acceptance: NR;

Satisfaction: NR;

Drop-out: 4.35%