The goal of this single-subject design is to evaluate an intervention combining neuromodulation, virtual reality, and muscle vibration to reduce neuropathic pain in individuals following a spinal cord injury. The investigators aim to quantify the effects of the intervention on the intensity and characteristics of neuropathic pain, as well as its impact on daily functioning in individuals undergoing SCI rehabilitation. Additionally, the investigators seek to gain a better understanding of participants' experiences with the intervention by exploring effects not captured by standardized questionnaires, and by examining the role and meaning of the intervention in their management and experience of pain. Finally, the investigators aim to assess the feasibility and clinical relevance of implementing this intervention in a rehabilitation setting. All participants living with neuropathic pain following a spinal cord injury will take part in ten intervention sessions. They will also be invited to complete standardized questionnaires and participate in a semi-structured interview. In addition, their clinicians will be invited to participate in a focus group.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
TREATMENT
Masking
NONE
Enrollment
10
tDCS will be delivered over the primary motor cortex (M1) to maximize the analgesic effect. The cathode will be positioned over the suborbital region, and the anode over M1 (position C3 or C4 of the international 10-20 system). A 2 mA direct current will be applied. Participants will observe, through virtual reality goggles (HTC Vive), an avatar walking from a first-person perspective, synchronized with the vibration pattern. Twelve vibrators will be placed transversely and bilaterally over the tendons of the main flexors and extensors of the lower limbs. The pattern used to trigger the vibrators is based on the natural sequence of gait movement. Muscle vibration induces a perception of movement in the direction of muscle elongation. The target frequency of the vibrators will be 80 Hz. The session will begin with 5 minutes of tDCS alone, and then for the last 15minutes the investigators will combine tDCS, virtual reality and muscle vibration.
Pain intensity
Pain intensity will be measured with Numeric rating scale, an 11-point scale to measure pain intensity, ranging from 0 (no pain) to 10 (worst possible pain). In the case of pain after spinal cord injury, the minimum clinically significant change would be around 1.8 points. Test-retest reliability ranged from 0.63 to 0.92, with intra- and inter-rater reliability of 0.84-0.98
Time frame: Phase A (baseline): once daily from Day 1 to Day 7 Phase B (intervention): before and after each session, 2-3 sessions per week, for up to 4 weeks (10 sessions total). Phase C (follow up): at 1 month and 4 months after the end of the intervention.
Pain interference
The investigators extracted the interference section containing 3 items from the "international spinal cord injury pain basic data set data collection form - Version 3.0" in order to measure pain interference on daily activities, mood and sleep over the last 7 days. For each self-administered question, interference is measured on a scale from 0 (no interference) to 10 (maximum interference). The total score ranges from 0 to 30, a higher score means a greater pain interference.This questionnaire has been validated in people after spinal cord injury.
Time frame: Phase A (baseline): Day 1 and Day 7. Phase B (intervention): after session 5 (week 2) and session 10 (week 4). (10 sessions total, 2-3 per week, for up to 4 weeks) Phase C (follow up) : at 1 month and 4 months after the end of the intervention.
Pain characteristics
Pain characteristics measured with PainDETECT. A tool initially developed to detect neuropathic components in people with chronic pain in the lumbar region. This questionnaire is increasingly used for other conditions, including post-spinal cord injury, helping to establish an individualized pain profile. It is also used in brain imaging studies. There are 9 items, 7 on sensory characteristics and 2 on temporal and spatial characteristics. It is scored from 0 to 38. A total of 19 or more indicates a high probability of having a neuropathic component.
Time frame: Phase A (baseline): Day 1 and Day 7. Phase B (intervention): after session 5 (week 2) and session 10 (week 4). (10 sessions total, 2-3 per week, for up to 4 weeks) Phase C (follow up): at 1 month and 4 months after the end of the intervention.
Participant satisfaction rating for the Intervention
The research team developed a questionnaire to assess overall satisfaction with the intervention, as well as satisfaction with the timing, frequency, duration, content, and format of the sessions. There are 9 items, the satisfaction related to each item is scored on a scale 0 (not at all satisfied) to 10 (extremely satisfied). The total score ranges from 0 to 90, a higher score means a greater satisfaction of the participant regarding the intervention.
Time frame: At the 10th (final) session (during phase B), in Week 4, assuming 10 sessions are conducted at a frequency of 2-3 per week.
Qualitative themes from semi-structured interviews on perceived effects, embodiment, feasibility, and personal impact of the intervention in the participant with neuropathic pain after a spinal cord injury (SCI)
Semi-structured interviews will be conducted with participants with neuropathic pain after a SCI. Each interview will last approximately 60 minutes and will follow a guide developed to structure the discussion. Thematic areas will include rehabilitation needs, overall experience with the intervention, perceived effects, embodiment, feasibility, suggestions regarding both positive and negative aspects, and for improving the intervention (for example in terms of effects or feasibility). How the intervention contributes to individuals' self-perception and interpretation of their pain experience will be also investigated. These interviews will be audio-recorded.
Time frame: At the 10th (final) session (phase B), in week 4, assuming 10 sessions are conducted at a frequency of 2-3 per week
Qualitative themes identified through focus groups with clinicians on the perceived role, implementation, and impact of the intervention
Focus group will be conducted with clinicians. Each interview will last approximately 90 minutes and will follow a guide developed to structure the discussion. Thematic areas will include the role of the intervention in patient care, clinical relevance, necessary changes and tools kit for implementation, perceived changes observed in patients, as well as both positive and negative aspects.
Time frame: 3 to 6months after the end of the intervention
Intervention sessions adherence rate
Adherence to intervention sessions will be collected. It will be calculated as a percentage: the number of sessions completed divided by the number of sessions planned, multiplied by 100. The total score ranges from 0% to 100%, with higher scores indicating greater adherence to the sessions.
Time frame: At the end of phase B, in week 4, assuming 10 sessions are conducted at a frequency of 2-3 per week
Rate of submission of baseline questionnaires
The rate of submission of the evaluation questionnaires will be collected. It will be calculated as a percentage: the number of questionnaires completed divided by the number of questionnaires expected (phase A), multiplied by 100. The total score ranges from 0% to 100%, with higher scores indicating greater adherence to the questionnaire.
Time frame: When the participant has completed phase A. In phase A, the protocole includes 7 times of evaluation Day 1 to Day 7.
Recruitment rate
The investigators will calculate the recruitment rate as the percentage of participants who actually enrolled in the study out of the total number of potential participants who were approached and expressed interest,multiplied by 100. The total score ranges from 0% to 100%, with higher scores indicating greater recruitment rate.
Time frame: At the end of the project, after all participants have been recruited (in 2 years).
participants' perception of walking during the session
After each intervention session, the investigators will ask participants to rate their perception of walking during the intervention stimulation using a numeric rating scale between 0 "The perception was not at all a perception of gait motion" and 10 "The perception was definitely a perception of gait motion". If the score is below 5/10, open-ended questions such as "What did you feel during the sessions?" and "How would you describe your sensations?" to explore whether participants experienced a perception of walking, and to rate how strong that perception was on a scale from 0 to 10.
Time frame: During phase B (intervention): after each intervention session, 2-3 sessions per week, for up to 4 weeks (10 sessions total)
The session duration with the technologies (both installation and treatment)
The total session duration, including the time required for installation and the actual treatment using the technologies, will be documented. Based on preliminary trials with partner patients, investigators expect an average duration of 40 minutes (20 minutes for installation and 20 minutes for treatment). Any deviations from this expected duration, including delays, will be documented and used to assess the feasibility of the project.
Time frame: During phase B (intervention): for each session, 2-3 sessions per week, for up to 4 weeks (10 sessions total)
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