The journal of pain : official journal of the American Pain Society
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Genetic variations in the catecholaminergic and serotonergic pathways may contribute to the development and severity of persistent breast pain. However, investigations of these associations are limited. The purpose of this study was to evaluate for associations between breast pain phenotypes and single nucleotide polymorphisms among 15 genes involved in catecholaminergic and serotonergic neurotransmission. ⋯ Polymorphisms in 3 genes were associated with membership in the moderate pain class: 5-hydroxytryptamine receptor 2A (HTR2A) rs2296972, SLC6A2 rs17841327, and SLC6A3 rs403636. Polymorphisms in 3 genes were associated with membership in the severe pain class: COMT HPS haplotype, SLC family 6 member 2-noradrenaline transporter (SLC6A2) HapD01, and SLC family 6 member 3-noradrenaline transporter (SLC6A3) rs464049. The identification of these associations suggest possible underlying mechanisms that play a role in the development and severity of persistent breast pain.
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Randomized Controlled Trial
Ultrasound-Guided Application of Percutaneous Electrolysis as an Adjunct to Exercise and Manual Therapy for Subacromial Pain Syndrome: A Randomized Clinical Trial.
This randomized clinical trial compared the effects of adding ultrasound (US)-guided percutaneouselectrolysis into a program consisting of manual therapy and exercise on pain, shoulder-related disability, function, and pressure sensitivity in subacromial pain syndrome. Fifty patients with subacromial pain syndrome were randomized into manual therapy and exercise or percutaneous electrolysis group. All patients received the same manual therapy and exercise program, 1 session per week for 5 consecutive weeks. ⋯ The current clinical trial found that the inclusion of US-guided percutaneous electrolysis in combination with manual therapy and exercise resulted in no significant differences for related disability (DASH) compared with the application of manual therapy and exercise alone in patients with subacromial pain syndrome. Nevertheless, differences were reported for some secondary outcomes such as shoulder pain and function (SPADI). Whether these effects are reliable should be addressed in future studies.
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Clinical evidence suggests that vitamin C (Vit C) may protect against the development of complex regional pain syndrome (CRPS) after fracture or surgery. Tibia fracture followed by 4 weeks of cast immobilization (fracture/cast) in rats results in nociceptive, vascular, and bone changes resembling clinical CRPS. In this study, fracture/cast rats were treated with the oxidative stress inhibitors Vit C, N-acetyl cysteine, or 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl to examine their effects on CRPS-related nociceptive and vascular changes. ⋯ Treatments with Vit C and N-acetyl cysteine reduced the oxidative stress markers malondialdehyde in the skin, muscle, and sciatic nerve, and lactate in the gastrocnemius muscle of the fracture/cast limb. Furthermore, Vit C treatment inhibited the post-fracture upregulation of substance P and calcitonin gene-related peptide in the sciatic nerve and the increased expression of the pain-related inflammatory mediators, including interleukin (IL)-6, and nerve growth factor in the skin and IL-1β, and IL-6 in the muscle of the post-fracture/cast limb. These data suggest that oxidative stress may contribute to the nociceptive features of the rat CRPS model.
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Opioid misuse is regularly associated with disrupted functioning in those with chronic pain. Less work has examined whether alcohol misuse may also interfere with functioning. This study examined frequency of opioid and alcohol misuse in 131 individuals (61.1% female) prescribed opioids for the treatment of chronic pain. ⋯ No differences were indicated between the latter 2 groups. Overall, the observed frequency of opioid misuse was somewhat higher in comparison to previous work (approximately 1 out of every 3 participants), and misuse of both alcohol and opioids was common (approximately 1 out of every 5 participants). While these data are preliminary, they do suggest that issues of substance misuse in those with chronic pain extends beyond opioids alone.
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Morphine is a potent opioid analgesic used to alleviate moderate or severe pain, but the development of drug tolerance and dependence limits its use in pain management. Previous studies showed that cannabinoid type 2 (CB2) receptor ligands may modulate opioid effects. However, there is no report of the effect of CB2 receptor agonist on acute morphine tolerance and physical dependence. ⋯ Pretreatment with 3mg/kg AM1241 decreased the chronic morphine-induced Iba1 expression in spinal cord. Coadministration of AM1241 (3 mg/kg) reduced the production of interleukin-1β, tumor necrosis factor-α, and interleukin-6 induced by long-term and acute morphine treatment. Our findings suggest that the coadministration of the CB2 receptor agonist and morphine could increase morphine antinociception and reduce morphine tolerance and physical dependence in mice.