Pain
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Cannabinoids have previously been shown to possess analgesic properties in a model of visceral hyperalgesia in which the neurotrophin, nerve growth factor (NGF), plays a pivotal role. The purpose of this study was to investigate the antihyperalgesic effects of two cannabinoids in NGF-evoked visceral hyperalgesia in order to test the hypothesis that endocannabinoids may modulate the NGF-driven elements of inflammatory hyperalgesia. Intra-vesical installation of NGF replicates many features of visceral hyperalgesia, including a bladder hyper-reflexia and increased expression of the immediate early gene c fos in the spinal cord. ⋯ However, neither CB1 nor CB2 receptor antagonists altered the action of anandamide. PEA-induced reduction in Fos expression was abrogated by SR144528. These data add to the growing evidence of a therapeutic potential for cannabinoids, and support the hypothesis that the endogenous cannabinoid system modulates the NGF-mediated components of inflammatory processes.
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The effects of intrathecal (i.t.) administration of prostaglandin E2 (PGE2) and prostaglandin F2 (PGF2) on behavioral and spinal neuronal responses to mechanical and thermal stimuli were examined in rats. i.t. Administration of either PGE2 (1-100 nmol) or PGF2 (1-100 nmol) produced a robust, dose-dependent mechanical hyperalgesia, but only a weak thermal hyperalgesia and touch-evoked allodynia. Spinal administration of either PGE2 (100 pmol-100 nmol) or PGF2 (1-100 nmol) produced dose-dependent increases in responses of nociceptive specific (NS) neurons to mechanical stimuli, but only modest increases in wide dynamic range (WDR) neurons to mechanical stimuli. ⋯ Both PGE2 and PGF2 produced increases in background discharges of WDR and NS neurons, although this effect was most consistently observed with WDR neurons and PGE2. These behavioral and electrophysiological data suggest that mechanical hyperalgesia induced by spinal administration of PGE2 and PGF2 is mediated mainly by changes in NS neurons. The weak thermal hyperalgesia may reflect changes in WDR neurons.
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The purpose of this study was to assess the hypothesis that pain and depression negatively impact the cognitive functioning of individuals with rheumatoid arthritis (RA). One hundred twenty-one community-dwelling RA patients (ages 34-84) completed a battery of cognitive tasks and multiple measures of pain and depression. Structural equation modeling techniques were used to assess the relative contributions of pain, depression, and age to cognitive performance. ⋯ That is, when depression was entered into the analyses, the previously significant effects of pain on cognition were no longer found. Interestingly, depression still mediated the pain-cognition relationship even after controlling for age. These findings suggest the importance of both pain and depression for understanding cognitive function in RA and may have important implications for treating this disease.
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Cross-sectional studies have consistently shown a relationship between chronic widespread pain, the clinical hallmark of fibromyalgia, and psychological distress. These studies cannot distinguish the direction of any causal relationship. Recent population based studies have reported that such pain is predictive of future distress. ⋯ Chronic widespread pain was associated with increased levels of psychological distress at follow up. However, a more rigorous analysis indicated that the association between baseline pain status with future distress was explained by concomitant features of chronic pain rather than pain per se. These findings indicate that it is those persons with chronic widespread pain in the presence of other physical and psychosocial factors who will become distressed.
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Case Reports
Epidural spinal cord stimulation for the treatment of painful legs and moving toes syndrome.
A case of 51-year-old male with painful legs and moving toes syndrome was successfully treated with epidural spinal cord stimulation. He was previously treated with varieties of medication, epidural block, transcutaneous nerve stimulation, lumbar sympathetic block, with no or only a transient effect. Epidural spinal cord stimulation was applied by means of percutaneously inserted epidural electrodes connected to a percutaneous extension for 2-week test stimulation period and later to a permanent device (ITREL). Pain and involuntary movement were relieved almost completely during the stimulation and the effect was still evident 6 months later.