Pain Inhibition and Facilitation in Recurrent Low Back Pain

Study Overview
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Brief Summary
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This study evaluates psychophysical measures of pain inhibition and facilitation, along with cortical responses to different sensory stimuli, in patients with recurrent low back pain and matched healthy individuals.

Detailed Description
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Pain inhibitory and facilitatory mechanisms have been suggested to play a role in the development of persistent low back pain; however, there is still debate on when changes in these mechanisms occur. Similarly, evoked cortical responses can reflect neuroplastic changes in pain processing regions, which are also thought to play a role in the transition to persistent pain, but there is also debate on when these neuroplastic changes develop relative to low back pain. Therefore, this study will use patients with an intermediary clinical pain state, recurrent low back pain, and matched healthy control participants, to investigate within and between subject differences in pain inhibitory, facilitatory and neuroplastic mechanisms.

Official Title
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Pro-Nociceptive and Anti-Nociceptive Mechanisms Across an Episode of Recurrent Low Back Pain

Conditions
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Recurrent Low Back Pain, Healthy

Participation Criteria
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Eligibility Criteria
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Inclusion: Healthy men and women Aged 18-60 years No previous back pain OR >1 previous episode of low back pain in past 12 months No current back pain OR Pain in the region posteriorly between the inferior border of the 12th rib and the lower gluteal fold (low back pain) at time of recruitment lasting >24 hours Able to speak, read and understand English Exclusion: Pregnancy First episode of low back pain Low back pain associated with menstruation Chronic low back pain (continuous pain episode for >3 months) Currently seeking active treatment for low back pain Red flags symptoms 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 or other medication which may affect the trial Lack of ability to cooperate Recent history of acute pain particularly in the lower limbs (unless related to LBP) Abnormally disrupted sleep in 24 hours preceding experiment

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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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Recurrent Low Back Pain Patients<br>Participants experiencing a current episode of their recurrent non-specific low back pain at the time of recruitment. | |
| Healthy Volunteers<br>Participants matched in age and gender to one of the recurrent low back pain patients, with no significant past low back pain, chronic pain or other relevant medical disorders. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Conditioned Pain Modulation | Pressure pain threshold (kPa) as test stimulus before compared to during a pressure conditioning stimulus on the lower leg | Day 0 vs. Day 28 | 
| Temporal Summation of Pain | Pain rating (VAS) change over a series of 10 repeated mechanical stimuli | Day 0 vs. Day 28 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pressure Pain Thresholds | Threshold of pain detection (kPa) with handheld algometry over the low back and distant sites | Day 0 vs. Day 28 | 
| Thermal Pain Thresholds | Hot and cold pain detection thresholds (degrees) | Day 0 vs. Day 28 | 
| Two Point Discrimination | The smallest distance (mm) for which two separate points can be distinguished over the low back | Day 0 vs. Day 28 | 
| Proprioceptive Weighting | Center of pressure displacement during 1-minute of quiet standing | Day 0 vs. Day 28 | 
| Sensory Evoked Potentials | EEG signals recorded in response to laser and electrical stimuli applied to the back | Day 0 vs. Day 28 |