Pain
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Clinical Trial
Characterization of chronic pain and somatosensory function in spinal cord injury subjects.
The pathophysiology of the chronic pain following spinal cord injury (SCI) is unclear. In order to study it's underlying mechanism we characterized the neurological profile of SCI subjects with (SCIP) and without (SCINP) chronic pain. Characterization comprised of thermal threshold testing for warmth, cold and heat pain and tactile sensibility testing of touch, graphesthesia and identification of speed of movement of touch stimuli on the skin. ⋯ However, STT lesion is not a sufficient condition since it could also be found in SCINP. The abnormal evoked pain seen in SCIP is probably due to neuronal hyperexcitability in these subjects. The fact that apparently identical sensory impairments manifest as chronic pain and hyperexcitability in one subject but not in another implies that either genetic predisposition or subtle differences in the nature of spinal injury determine the emergence of chronic pain following SCI.
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Suicidal ideation among individuals suffering from chronically painful conditions has not been widely studied, although rates of completed suicide are believed to be elevated in this population relative to the general population. The psychiatric literature on suicide documents the importance of controlling for the severity of depression when studying factors associated with suicidal ideation, attempts, or completion. The present study examined the relationships between suicidal ideation and the experience of pain, pain-related disability, and pain coping efforts among a sample of individuals experiencing chronically painful conditions. ⋯ Depression, not suicidal status, consistently predicted level of functioning. The prevalence of suicidal intent was comparable to rates observed in other studies and relatively low. When individuals with chronic pain report suicidal intent, it is imperative that measures preventing self-harm be implemented immediately and the patient's depression be treated aggressively.
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Although the administration of opioids is the most effective treatment for pain, their efficacy is limited by the development of tolerance. The midbrain periaqueductal gray matter (PAG) participates in opioid analgesia and tolerance. Microinjection of morphine into PAG produces antinociception, probably through neurons in the rostral ventromedial medulla (RVM), namely through the activation of off-cells, which inhibit nociception, and the inhibition of on-cells, which facilitate nociception. ⋯ In contrast to saline-pretreated rats, PAG microinjection of morphine in tolerant animals did not change the baseline activity of off- or on-cells, did not prevent the off-cell pause or the on-cell activation upon tail heating, and did not lengthen the tail flick latency. However, microinjection of kainic acid into the PAG (1) caused off-cells to become continuously active and on-cells to become silent, and (2) prevented the tail flick, i.e. exactly what morphine did before tolerance developed. These results demonstrate a correspondence between neuronal and behavioral measures of tolerance to PAG opioid administration, and suggest that tolerance is mediated by a change in opioid-sensitive neurons within the PAG.
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Nerve growth factor (NGF) regulates the nociceptive properties including sensitivity to capsaicin of a subset of dorsal root ganglion neurons, which express the high-affinity NGF receptor, trkA. Capsaicin sensitivity co-localizes with the expression of a cloned capsaicin receptor, vanilloid receptor type 1 (VR-1), which displays properties similar to the native capsaicin response. ⋯ NGF treatment increased both VR-1 mRNA expression and capsaicin evoked release of CGRP. These effects were inhibited by treatment with the trkA inhibitor k252a.
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Randomized Controlled Trial Clinical Trial
A blind, randomized, controlled trial of cognitive-behavioural intervention for patients with recent onset rheumatoid arthritis: preventing psychological and physical morbidity.
This study examined the efficacy of a cognitive and behavioural intervention (CBT) for patients with recent onset, seropositive rheumatoid arthritis. Fifty-three participants with a diagnosis of classical or definite rheumatoid arthritis, who were seropositive and had less than 2 years of disease history were recruited into the trial. All participants received routine medical management during the study, although half were randomly allocated to receive an adjunctive psychological intervention. ⋯ At outcome but not follow-up, the CBT group also showed reduction in C-reactive protein levels. However, the CBT group did show significant improvement in joint involvement at 6-month follow-up compared with the Standard group, indicating physical improvements above those achieved with standard care. These results indicate that cognitive-behavioural intervention offered as an adjunct to standard clinical management early in the course of RA is efficacious in producing reductions in both psychological and physical morbidity