European journal of pain : EJP
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Clinical Trial Controlled Clinical Trial
Peripheral effects of needle stimulation (acupuncture) on skin and muscle blood flow in fibromyalgia.
Acupuncture has become a widely used treatment modality in various musculoskeletal pain conditions. Acupuncture is also shown to enhance blood flow and recovery in surgical flaps. The mechanisms behind the effect on blood flow were suggested to rely on vasoactive substances, such as calcitonin gene-related peptide, released from nociceptors by the needle stimulation. ⋯ The results of the present study were partly similar to those earlier found at a corresponding site in healthy female subjects, i.e., deep muscle stimulation resulted in larger increase in skin blood flow (mean (SE)): 62.4% (13.0) and muscle blood flow: 93.1% (18.6), compared to baseline, than did subcutaneous insertion (mean (SE) skin blood flow increase: 26.4% (6.2); muscle blood flow increase: 46.1% (10.2)). However, in FM patients subcutaneous needle insertion was followed by a significant increase in both skin and muscle blood flow, in contrast to findings in healthy subjects where no significant blood flow increase was found following the subcutaneous needling. The different results of subcutaneous needling between the groups (skin blood flow: p=0.008; muscle blood flow: p=0.027) may be related to a greater sensitivity to pain and other somatosensory input in FM.
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Cutting spinal nerves just distal to the dorsal root ganglion (DRG) triggers, with rapid onset, massive spontaneous ectopic discharge in axotomized afferent A-neurons, and at the same time induces tactile allodynia in the partially denervated hindlimb. We show that secondary transection of the dorsal root (rhizotomy) of the axotomized DRG, or suppression of the ectopia with topically applied local anesthetics, eliminates or attenuates the allodynia. ⋯ These observations support the hypothesis that ectopic firing in DRG A-neurons induces central sensitization which leads to tactile allodynia. The question of how activity in afferent A-neurons, which are not normally nociceptive, might induce allodynia is discussed in light of the current literature.
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The usefulness of the verbal pain rating scale (VRS) included in the Short Form 36 (SF-36) in identifying characteristics of long-term pain conditions, was analyzed using data from the 1994 Danish Health and Morbidity Survey. Based on the rating of pain intensity during a 4-week recall period the respondents were categorized into three groups: a high pain group (HPG) consisting of persons reporting moderate to severe pain (VRS 4-6), a low pain group (LPG) who rated their pain as very mild or mild (VRS 2-3), and a control group (CG) with no pain (VRS 1). The investigated sample comprised 3992 persons (HPG=563 persons, LPG=1714, and CG=1715 persons). ⋯ Mean numbers of in-hospital days were 1.60, 0.80, and 0.43 for the HPG, LPG, and CG, respectively. Our study suggest that one-dimensional pain intensity scoring using a simple VRS-scoring is useful as a screening instrument for identifying persons suffering from pain of a more complex nature. High intensity scores on a pain intensity scale should indicate to the investigator that she/he might be facing a person whose pain complaints and behavior are not only based on a pure biological background, but in whom also severe psychological and social problems might be present.
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Although cannabinoids have anti-hyperalgesic effects in animal models of nerve injury, there are currently very few prospective trials of the efficacy of cannabinoids in neuropathic pain in humans. This open label prospective study investigated the safety, tolerability and analgesic benefit of oral Delta-9-tetrahydrocannabinol (THC) titrated to a maximal dosage of 25 mg/day in 8 consecutive patients with chronic refractory neuropathic pain. Spontaneous ongoing and paroxysmal pain, allodynia and paresthesias were assessed. ⋯ Seven patients suffered from side effects necessitating premature arrest of the drug in 5 of them. THC (mean dosage: 16.6+/-6.5 mg/day) did not induce any significant effects on ongoing and paroxysmal pain, allodynia, quality of life, anxiety/depression scores and functional impact of pain. These results do not support an overall benefit of THC in pain and quality of life in patients with refractory neuropathic pain.
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Clinical Trial
Children's ratings of the intensity and unpleasantness of post-operative pain using facial expression scales.
This study explored whether global unidimensional self-report pain scales based on facial expression help children separately estimate the sensory and affective magnitude of post-operative pain. Ninety paediatric elective surgery patients (in two age groups: 5-9 and 10-15 years) used each of four scales to estimate pain intensity and pain affect during the first 2 days after surgery. The four scales were: Faces Pain Scale (FPS), Facial Affective Scale (FAS), and the Coloured Analogue Scale (CAS) (one for intensity and one for unpleasantness). ⋯ No systematic age effects were observed. It was concluded that the FPS and the FAS may partly measure different aspects of the postoperative pain experience in children, although shared instrument variance may obscure true estimates of covariation in ratings of intensity and affective magnitude. The clinical relevance of the present results remains to be determined.