European journal of pain : EJP
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This study examined the relative capacity of Adelta- and C-fibers to encode non-painful and painful brief CO(2) laser stimuli by comparing the effects of Adelta/C-fiber activation versus C-fiber activation alone. In nine normal subjects, brief CO(2) laser pulses of four different intensities (range 5.8-10.6mJ/mm(2)) were delivered at random on the first intermetacarpal zone of the dorsum of the hand. A-fiber pressure block of the superficial radial nerve was performed to fully isolate the activity of C-fibers. ⋯ Median RT increased from 492 to 1355ms. The late LEPs, attributed to the activation of Adelta-fibers, disappeared and ultra-late LEPs were recorded at Cz with a positivity peaking around 800ms. Collectively, these observations lead to the conclusion that Adelta-fibers are the main peripheral mediators for the perception of brief CO(2) laser stimuli and that they provide more sensory information than C-fibers.
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Randomized Controlled Trial Clinical Trial
Prophylactic tolperisone for post-exercise muscle soreness causes reduced isometric force--a double-blind randomized crossover control study.
The role of tolperisone hydrochloride, a centrally acting muscle relaxant in relieving painful muscle spasm is recently being discussed. The present study hypothesizes that the prophylactic use of tolperisone hydrochloride may effectively relieve post-exercise muscle soreness, based on the spasm theory of exercise pain. Twenty male volunteers, aged 25.2 +/- 0.82 years (mean +/- SEM) participated in 10 sessions in which they received oral treatment with placebo or the centrally acting muscle relaxant tolperisone hydrochloride (150 mg) three times daily for 8 days, in randomized crossover double-blind design. ⋯ The EMG RMS amplitude was also reduced immediately after the exercise, but was increased at 24 and 48 h. Isometric force was reduced immediately after the exercise as compared to days 1, 6, and the 24 and 48 h post-exercise assessments with a greater reduction following the tolperisone hydrochloride treatment and the reduction was more in tolperisone group as compared to the placebo group. The results suggest, that the prophylactic intake of tolperisone hydrochloride provides no relief to pain in course of post-exercise muscle soreness but results in reduction in isometric force.
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We investigated the literature of randomised placebo-controlled trials to find out if transcutaneous electrical nerve stimulation (TENS) or acupuncture-like transcutaneous electrical nerve stimulation (ALTENS) can reduce analgesic consumption after surgery. ⋯ TENS, administered with a strong, subnoxious intensity at an adequate frequency in the wound area, can significantly reduce analgesic consumption for postoperative pain.
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The effects of the S enantiomer of RB101, a complete inhibitor of enkephalin-catabolizing enzymes, alone or in combination with a functional NMDA receptor antagonist, (+)-HA966 were studied on the spinal c-Fos protein expression in the carrageenan model of inflammatory nociception. One hour 30min after intraplantar carrageenan in awake rats, c-Fos immunoreactive (c-Fos-IR) nuclei were preferentially located in the laminae I-II and V-VI of the spinal dorsal horn, i.e., spinal areas containing numerous neurons responding exclusively, or not, to peripheral nociceptive stimuli. RB101(S) (5, 10, 20 and 40mg/kg i.v.) dose-dependently reduced the total number of carrageenan-evoked c-Fos-IR nuclei (r=0.63, P<0.01), with 49+/-3% reduction (P<0.001) for the highest dose. ⋯ These effects were partially reversed by naloxone. These results provide evidence for the potent effects of combination of RB101(S) and (+)-HA966. Considering the absence of major opioid side effects of RB101(S) and the marked increase of its antinociceptive effects by NMDA receptor antagonist, this type of drug combination could have beneficial therapeutical application.
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Attentional bias in patients with chronic pain was investigated using the emotional Stroop task with personalized pain words. A group of 20 chronic pain patients with 20 matched controls participated in the experiment. Before administration of the emotional Stroop patients were asked to select the five best descriptors of their pain from a list of 19 sensory pain descriptors. ⋯ Results showed a weak Stroop interference effect with slower reaction times to pain words in the patient group, but they did not differ significantly from the controls. Both groups were slower on the threat words and displayed the classical Stroop interference effect for color words. The overall pattern of results are in line with previous Stroop studies on pain patients showing weak support for the attentional bias hypothesis.