European journal of pain : EJP
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Comparative Study
A comparison of the relationship between depression, perceived disability, and physical performance in persons with chronic pain.
This study examined the relationships between self-report of depressive symptoms, perceived disability, and physical performance among 267 persons with chronic pain. Prior research has reported a relationship between depression and disability using self-report measures. However, self-report instruments may be prone to biases associated with depression as depressed persons with pain may have an exaggerated negative view of their level of function. ⋯ The magnitude of the relationships between depression and self-report and functional activity were similar, suggesting that a self-report bias associated with depression is not responsible for an observed relationship between depression and disability. Physiologic effort partially mediated the relationship between depression and physical performance. The findings further highlight the importance of depression in the experience of chronic pain.
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The mechanism underlying discogenic low-back pain is unclear. It is difficult to explain this type of pain by the segmental innervation theory because the groin area is innervated by the genitofemoral or ilioinguinal nerves, which are the terminal branches of the L1 or L2 spinal nerves. Recently, some studies have indicated that sympathetic trunks are closely related to discogenic low-back pain. ⋯ We demonstrated that FG-labeled SP-ir neurons in L2 DRGs decreased when FG was applied to the ventral or dorsal portions of L5-6 discs. The results indicated that the L2 ramus communicans played an important role in the afferent pathway of both the ventral and dorsal portions of the L5-6 disc. Nociceptive information from the L5-6 disc may be transmitted mainly by L2 DRG neurons through the L2 ramus communicans.
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Mice lacking the serotonin-transporter (5-HTT-/- mice) develop reduced thermal hyperalgesia after nerve injury, concomitant with reduced serotonin (5-HT) levels in nervous tissue. Here we investigated pain behaviour in 5-HTT-/- mice compared to their wild type littermates after hind paw inflammation induced by complete Freund's adjuvant (CFA). We used standard tests for pain behaviour, high performance liquid chromatography for measurement of 5-HT, and immunohistochemistry of hind paw skin tissue and L5 dorsal root ganglia (DRG) to measure local inflammation and nerve injury. ⋯ Accordingly, a higher number of injured DRG neurons was identified by activating transcription factor 3 (ATF3) staining in 5-HTT-/- mice after CFA. We conclude that the phenotype of 5-HTT-/- mice leads to reduced inflammatory pain due to reduced tissue 5-HT levels and to greater peripheral nerve injury after inflammation. Human variants of the 5-HTT genotypes might be part of the factors determining the extent of nerve injury and hyperalgesia in inflammation.
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Randomized Controlled Trial
Effects of simultaneous dual-site TENS stimulation on experimental pain.
Transcutaneous electrical nerve stimulation (TENS) is commonly used for pain relief. However, little robust research exists regarding the combination of parameters required to provide effective doses. This study investigated the hypoalgesic effects of different parameter combinations, applied simultaneously at two sites (segmental and extrasegmental), on pressure pain threshold (PPT) in pain-free humans. ⋯ Those groups using high-intensity stimulation at the segmental stimulation sites showed significantly greater hypoalgesia than placebo (p < 0.025 in each case). The largest hypoalgesic effect was for simultaneous high-intensity stimulation at segmental and extrasegmental sites, using different frequencies. These results reaffirm that high-intensity stimulation (regardless of frequency) is of fundamental importance in effective dosage.
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Randomized Controlled Trial
A randomized controlled trial of exposure in vivo for patients with spinal pain reporting fear of work-related activities.
Pain-related fear is related to disability in persistent pain conditions. Exposure treatment has been reported to be of great benefit in replicated single case experiments. ⋯ Compared to a group receiving usual treatment and waiting for exposure, the exposure in vivo group demonstrated a significantly larger improvement on function. Overall exposure had moderate effects on function, fear and pain intensity. We conclude that exposure may be important in treatment, but is not recommended as a "stand alone" adjunct to usual treatment.