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.
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.
Study Type
OBSERVATIONAL
Enrollment
50
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.
These participants must not have presented episodes of low back pain for more than 7 days in the last 12 months.
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).
Time frame: 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).
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.
Time frame: 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.
Time frame: 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.
Time frame: 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).
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