Enhancing Inhibition With tDCS in Low Back Pain

Study Overview
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Brief Summary
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This cross-over study intends to use consecutive days of active versus sham transcranial direct current stimulation (tDCS) to enhance descending inhibition and look at resulting clinical effects in people with low back pain.

Official Title
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Enhancing Inhibition With tDCS in Low Back Pain

Conditions
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Low Back Pain

Intervention / Treatment
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* Device: High-Definition Transcranial Direct Current Stimulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Otherwise healthy men and women Aged 18-60 years Continuous pain (>3days pain/week) episode lasting at least 3 months, sufficient to limit daily activities Pain in the region posteriorly between the inferior border of the 12th rib and the lower gluteal fold (low back pain) at the time of recruitment Able to speak, read and understand English Exclusion Criteria: Pregnancy Low back pain associated with menstruation Currently seeking active treatment for low back pain Red flags symptoms (i.e. fever, malaise, progressive neurologic deficit, significant trauma, prolonged corticosteroid use or osteoporosis, pain worst at night, urinary or faecal incontinence, or unintended weight loss) Drug addiction defined as the use of cannabis, opioids or other drugs Current or previous neurologic, musculoskeletal, mental, or other illnesses which may affect the trial Current or previous chronic or recurrent pain condition other than low back pain Current regular use of analgesic medication or other medication which may affect the trial Lack of ability to cooperate

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Active tDCS<br>30s ramp to 2mA with 20 minute session of active High-Definition Transcranial Direct Current Stimulation at 2mA | Device: High-Definition Transcranial Direct Current Stimulation<br>* Device uses an array of electrodes over the scalp, in contact via gel, to provide a weak electrical current.<br>|
| Placebo Comparator: Sham tDCS<br>30s ramp to 2mA with High-Definition Transcranial Direct Current Stimulation, then device stops stimulating for 20 minutes | Device: High-Definition Transcranial Direct Current Stimulation<br>* Device uses an array of electrodes over the scalp, in contact via gel, to provide a weak electrical current.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Conditioned Pain Modulation | Change in cuff pain threshold with contralateral cuff conditioning stimulus | Day 0 (Pre) to Day 3 (Post) in each stimulation phase | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Temporal Summation of Pain | Change in pain intensity ratings (i.e. on an electronic Visual Analogue Scale from 0=no pain to 10=worst pain imaginable) across series of 10 x 1s cuff stimuli at 0.5Hz (scores are normalized to first rating by subtraction and grouped into 3 epochs of 3 inflations with higher change scores indicating higher summation/facilitation) | Day 1 (Pre) to Day 3 (Post) in each stimulation phase | 
| Pressure Pain Thresholds | Handheld algometry over the extensor carpi radialis, upper trapezius, lower back and gastrocnemius muscles | Day 1 (Pre) to Day 3 (Post) in each stimulation phase | 
| Pain Intensity | Visual Analogue Scale from 0=no pain to 10=worst pain imaginable currently at rest and with worst movement, as well as maximum in past week | Day 0 (Pre) to Day 3 (Post) and 2 weeks post for each stimulation phase | 
| Pain Unpleasantness | Visual Analogue Scale from 0=not unpleasant at all to 10=most unpleasant sensation imaginable currently at rest and with worst movement, as well as maximum in past week | Day 0 (Pre) to Day 3 (Post) and 2 weeks post for each stimulation phase | 
| Pain Area | Total number of pixels coloured on an electronic body chart (Navigate Pain) | Day 0 (Pre) to Day 3 (Post) and 2 weeks post for each stimulation phase | 
| Roland-Morris Disability Questionnaire | Measures back-related disability for 24 statements of potentially afflicted tasks with dichotomous responses. Minimum 0 to maximum 24 with higher scores indicating worse disability. | Day 0 (Pre) to Day 3 (Post) and 2 weeks post for each stimulation phase | 
| Back Performance Scale | 5 Task scale rated as per performance as a functional measure of back-related disability (each task is rated on a 4 point Likert scale 0-3 and summed to give total), scored from 0-15 with higher scores indicating more pain and dysfunction during task performance. Here will be used to characterize functional disability. | Day 0 (Pre) to Day 3 (Post) and 2 weeks post for each stimulation phase |