Assessment of LTP-like Pain Amplification in Chronic Low Back Pain Patients

Study Overview
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Brief Summary
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The present study is aimed to assess the LTP-like pain amplification in chronic low back pain patients to explore the central and peripheral effect for pain LTP.

Detailed Description
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This study is a cross-sectional study. Two groups, including low back pain group and healthy subjects group will be arranged in this study. 50 subjects will be recruited in each group, The healthy subjects were matched for sex and age in relation to the low back pain group. Conditioning electrical stimulation (100 Hz, repeated 5 times with 10 s intervals, 500 impulses) using circular pin electrodes will be used in both groups to induce LTP-like pain amplification. The pain intensity changes to pinprick and light touch stimuli will be compared between two groups.

Official Title
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Assessment of Long-term Potentiation (LTP)-Like Pain Amplification in Chronic Low Back Pain Patients

Conditions
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Low Back Pain

Intervention / Treatment
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* Other: Chronic low back pain patients
* Other: Subjects without chronic low back pain


Participation Criteria
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Eligibility Criteria
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Chronic low back pain patients Inclusion Criteria: Age 21-80 years old. People must have experienced low back pain for at least 3 months and have reported a minimal pain level of 30 (pain threshold) on the 0-100 pain numerical rating scale (NRS) in the last 7 days. Exclusion Criteria: Age below 21 or over 80 years old. Patients were excluded if they had taken pain medications on the day of the assessment or if they had serious spinal pathologies, such as fractures, tumors or inflammatory diseases, such as ankylosing spondylitis, nerve root compromise confirmed by clinical neurological tests or severe cardiorespiratory diseases. Those who were pregnant, patients with cancer and those with a cardiac pacemaker were also excluded. Healthy volunteers. Inclusion Criteria: Age 21-80 years old. These participants must not have presented episodes of low back pain for more than 7 days in the last 12 months. Exclusion Criteria: Age below 21 or over 80 years old. These participants have presented episodes of low back pain for more than 7 days in the last 12 months.

Ages Eligible for Study
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Minimum Age: 20 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 |
| --- | --- |
| Chronic low back pain patients<br>People must have experienced low back pain for at least 3 months and have reported a minimal pain level of 30 (pain threshold) on the 0-100 pain numerical rating scale (NRS) in the last 7 days. | Other: Chronic low back pain patients<br>* People must have experienced low back pain for at least 3 months and have reported a minimal pain level of 30 (pain threshold) on the 0-100 pain numerical rating scale (NRS) in the last 7 days.<br>|
| Subjects without chronic low back pain<br>Participants must not have presented episodes of low back pain for more than 7 days in the last 12 months. | Other: Subjects without chronic low back pain<br>* These participants must not have presented episodes of low back pain for more than 7 days in the last 12 months.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change of pain intensity to pinprick stimuli | Mechanical pinprick-evoked perception was assessed by three weighted pinprick stimulators which were randomly applied in the area adjacent to the conditioned site. The subjects indicated the perceived intensity on the same visual analogue scale(VAS). | The pinprick sensation will be measured three times before and six times after the conditioning electrical stimulation with 10 minutes interval throughout the experiment (90 minutes). | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Perception Features of conditioning electrical stimulation (CES) | The subjects were asked to rate continuously the magnitude of pain induced by the 100 Hz CES using a hand-held visual analogue scale (VAS) device. These VAS ratings were sampled by a computer. The VAS ranges from 0(no sensation) to 100 (most imaginable pain) where 30 means pain threshold. | All subjects will rate the pain ratings during the 50 seconds stimulation. | 
| Change of pain intensity to light-stroking stimuli | A cotton swab was used for light stroking stimuli ( 100mN) for assessing the tactile perception around the conditioned site. | The light-touch sensation will be measured three times before and six times after the conditioning electrical stimulation with 10 minutes interval throughout the experiment (90 minutes). | 
| Change of pain intensity to single electrical stimulation (SES) | A single rectangular 1 ms constant-current electrical stimulation was applied as a homotopic electrical test stimulus using the same conditioning electrode placed at the conditioned site. | The pain ratings to SES will be measured three times before and six times after the conditioning electrical stimulation with 10 minutes interval throughout the experiment (90 minutes). | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Low back pain, Long-term potentiation, Hyperalgesia, Allodynia