European journal of pain : EJP
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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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Loss of spinal inhibitory mechanisms is thought to contribute to the pathophysiology of abnormal pain states, including neuropathic pain. By using an evoked spinal field potential technique, the hypothesis was tested here that decreased spinal GABAergic control underlies poor response to morphine (MOR) that often accompanies neuropathic pain. Therefore, field potentials evoked by electrical peripheral nerve stimulation during spinal superfusion with MOR were recorded in rats rendered neuropathic by a spinal nerve ligation (SNL) procedure, and compared to responses recorded in naïve rats. ⋯ Two-way analysis of variance revealed no interaction of MOR with either CGP354348 (p = 0.42) or BIC (p = 0.14). Evidence is presented here that injury to the primary afferent system results in significant changes in the ability of spinal MOR to depress field potentials evoked by peripheral input. However, the present findings do not support a pathogenic role for decreased GABAergic inhibition in such changes.
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Early identification and intervention with those that run the risk of developing long-term disability would offer a great opportunity for reducing costs and personal suffering associated with long-term work absenteeism. The Orebro Musculoskeletal Pain Screening Questionnaire (OMPSQ) has been used and validated in several studies for participants with mainly acute pain problems. The aim of this study was to validate the OMPSQ for patients with non-acute pain problems (e.g. 1-6 months sick leave) and compare to other relevant questionnaires. ⋯ The results demonstrate that psychosocial factors as measured by OMPSQ are related to work disability and perceived health even 3 years after treatment for patients with non-acute pain problems. The OMSPQ was a good predictor of outcome.
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Randomized Controlled Trial Comparative Study
Millimetre wave therapy for pain relief after total knee arthroplasty: a randomised controlled trial.
Millimetre wave therapy (MWT) is a promising complementary method for pain relief, however rigorous investigations of its effectiveness are needed. The purpose of this study was to examine if MWT can reduce opioid requirement compared to sham procedure applied for relief of acute pain in patients after total knee arthroplasty (TKA). Eighty patients undergoing TKA were randomly assigned to receive MWT or sham procedure. ⋯ Secondary outcome measures were also comparable in both groups. The majority of patients in both groups believed they had received true MWT and wanted to repeat it in future. Millimetre waves applied to surfaces of surgical wounds did not reduce opioid requirement compared to the sham procedure after TKA.