European journal of pain : EJP
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Glutamate may be released from muscle nociceptors and thereby contribute to mechanisms underlying acute and chronic muscle pain. In vivo concentration of glutamate during muscle pain has not previously been studied in either animals or humans. In the present study, we aimed to study the in vivo concentration of glutamate before, during and after acute pain of trapezius muscle in humans using the microdialysis technique. ⋯ Muscle blood flow increased significantly over time in response to infusion of chemical mixture and placebo (p = 0.001). However, we found no difference in changes in muscle blood flow between chemical mixture and placebo (p > 0.05). In conclusion, the present study demonstrates no signs of increased release of glutamate from myofascial nociceptors during and after acute experimentally induced muscle pain and tenderness.
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This study was designed to assess the impact of a refractory angina programme on the health related quality of life for patients with chronic refractory angina (CRA) one year following enrolment. ⋯ Implementation of the national refractory angina guidelines in a prospective study of 69 consecutive CRA patients significantly improved health related quality of life status at one year.
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It is well known that the response to painful stimuli varies between individuals and this could be consequence of individual differences to pain sensitivity that may be related to genetic factors. Catechol-O-methyltransferase (COMT) is one of the enzymes that metabolize catecholamine neurotransmitters. Differences in the activity of COMT influence the functions of these neurotransmitters. ⋯ To elucidate the possible role of COMT polymorphism in the susceptibility to neuropathic pain, we have performed a case-control study in a Spanish population. Analysis of the (Val158Met) COMT polymorphism was performed by PCR amplification and DNA digestion with restriction enzymes. Our study concludes that functional Val158Met polymorphism of COMT gene is not associated to increased susceptibility to neuropathic pain.
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Comparative Study
Effects of pulsed versus conventional radiofrequency current on rabbit dorsal root ganglion morphology.
Lesioning using radiofrequency (RF) current has been increasingly used in clinical practice for the treatment of pain syndromes. Although formation of heat causing "thermocoagulation" of the nervous tissues is thought to be responsible of the clinical outcome, a more recent modality of RF application named pulsed radiofrequency (PRF) delivers the RF current without producing destructive levels of heat. In our study, we compared the effects of conventional RF (CRF) and PRF on rabbit dorsal root ganglion (DRG) morphology, including also control and sham operated groups. ⋯ The myelinated and unmyelinated nerve fibers were of normal morphology in all groups. Our results suggest that PRF application is less destructive of cellular morphology than CRF at clinically used "doses". Before making certain judgements, more experimental and clinical studies should be planned.
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Randomized Controlled Trial Clinical Trial
The causal status of pain catastrophizing: an experimental test with healthy participants.
In the current study we report findings on the effects of experimentally induced catastrophizing about pain on expected pain, experienced pain and escape/avoidance behavior during a cold pressor task in a sample of healthy participants. It was hypothesized that increasing the level of catastrophizing would result in a higher level of expected pain, a higher level of experienced pain, and a shorter duration of ice-water immersion. ⋯ The results demonstrated that despite the successful attempt to induce catastrophizing, this neither significantly affected expected pain, experienced pain, and duration of ice-water immersion, nor were these relations moderated by the pre-experimental level of catastrophizing. Although the level of catastrophizing was successfully manipulated, more similar experiments are necessary in order to give a more definite answer on the possible causal status of pain catastrophizing.