European journal of pain : EJP
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Endothelins (ETs) contribute to the sensory changes seen in animals models of inflammatory, cancer and diabetic neuropathic pain, but little is known about their nociceptive role following peripheral nerve injury. The current study evaluated mechanisms by which ETs can drive changes in nociceptive responses to thermal stimulation of the hind paw of rats induced by unilateral lumbar L5/L6 spinal nerve ligation (SNL) injury. SNL sensitizes rats to acetone-evoked cooling of and radiant heat application (Hargreaves test) to the ipsilateral hind paw (throughout 3-40 and 9-40 days after surgery, respectively). ⋯ SNL enhanced the [Ca(+2)](i) increases induced by ET-1 (100 nM) in neurons from L5/L6 (injured) and L4 (intact) cultured dorsal root ganglion, but did not change the responses of non-neuronal cells. Furthermore, Western blot analysis revealed that SNL increased ET(A) and ET(B) receptor protein expression in spinal nerves. Thus, SNL induces marked hind paw hypersensitivity to thermal stimulation in part via up-regulation of peripheral sensory nerve pronociceptive ET(A) and ET(B) receptor-operated mechanisms.
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Chronic headache is one of the most prominent symptoms among subjects with traumatic head injury (THI). Despite the relatively high prevalence of chronic post-traumatic headache (CPTHA) and its enormous effect on the already poor quality of life of subjects with THI, its mechanisms has not been studied in depth. ⋯ The sensory profile of subjects with CPTHA suggests that CPTHA may be a form of central pain. The cranial mechanical hyperalgesia may originate from peripheral tissue damage accompanying the THI. Psychological factors may contribute to the development, and maintenance of CPTHA in susceptible individuals.
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Randomized Controlled Trial
Catastrophizing moderates the effect of exposure in vivo for back pain patients with pain-related fear.
This investigation was an initial attempt to explore psychological factors that might help or hinder the effect of exposure in vivo for patients with musculoskeletal pain and pain-related fear. The study was based on data from a randomized-controlled trial for patients with non-specific spinal pain (Linton et al., 2008). First, catastrophizing, anxiety, and depression were studied as possible treatment moderators. ⋯ Next, patients were divided into high change participants and low change participants based on their improvement in disability after treatment in order to investigate the change in psychological variables during treatment. Descriptive data indicated that high change participants had large improvements across treatment on depression, anxiety, catastrophizing, and fear-avoidance beliefs whereas low change participants virtually did not change at all on these variables across treatment. These findings denote that catastrophizing is a moderator of treatment outcome in exposure whereas several psychological variables might be important for the treatment process.
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Why traumatic injuries to the peripheral nervous system infrequently result in neuropathic pain is still unknown. The aim of this study was to examine the somatosensory system in patients with traumatic peripheral nerve injury with and without pain to try to unravel possible links to mechanisms underlying development and maintenance of pain. Eighteen patients with spontaneous ongoing pain and 16 patients without pain after unilateral partial peripheral traumatic nerve injury were studied. ⋯ There were no side differences in stimulus-response functions using painful heat stimuli in any of the groups. In addition, no significant difference could be demonstrated in any sensory modality comparing side-to-side differences between the two groups. In conclusion, increased pain sensitivity to cold and pressure was found on the injured side in pain patients, pointing to hyperexcitability in the pain system, a finding not verified by a more challenging analysis of side-to-side differences between patients with and without pain.
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Accurate assessment of adolescent chronic pain is critical to guiding treatment decisions. Given the multifaceted role of the parents in their children's lives, parents, and patients often each provide reports of adolescents' pain-related functioning. In order to make sense of these data, clinicians should be aware of patterns of discordance in perspectives. ⋯ Analyses suggested that high pain and being older predicted greater concordance in ratings. Findings suggest that mothers and adolescents tended to have greater concordance for more observable and shared disability (e.g., physical disability, family functioning) and greater discordance for internal experiences (e.g., pain-specific anxiety, depression). Awareness of these patterns of concordance and discordance should help clinicians in interpreting mothers' proxy-reports and adolescents' self-reports of chronic pain-related functioning.