European journal of pain : EJP
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Many patients with multiple sclerosis (MS) develop central neuropathic pain (CP). In the present study somatosensory abnormalities have been analysed in detail in 62 patients with MS and CP (42 women, 20 men; mean age 52 years) and in a control group of 10 women and 6 men (mean age 47 years) with MS and sensory symptoms, but without pain. Assessment included clinical testing and quantitative methods (QST) for the measurement of perception thresholds for touch, vibration, and temperatures. ⋯ Comparisons between painful and non-painful regions showed both the absolute threshold values and the index values to be significantly more abnormal, in the CP regions, for warmth (p<0.001), cold (p<0.05), difference limen (innoxious warmth and cold, p<0.01), cold pain (p<0.01) and heat pain/cold pain combined (p<0.001). Also the comparisons between regions with central pain and regions with sensory symptoms in the controls showed significantly more abnormal thresholds in the CP patients for warmth (p<0.05), cold (p<0.01), difference limen (innoxious warmth and cold, p<0.01) and heat pain/cold pain combined (p<0.001). The results support the general hypothesis that only patients who have lesions affecting the spinothalamo-cortical pathways run the risk of developing central pain.
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In our previous studies, psychological stress was shown to enhance operant escape responding of male and female rats. The stressors that produced hyperalgesia were physical restraint and social defeat. Nociceptive input also elicits stress reactions, generating the prediction that pain would facilitate pain under certain circumstances. ⋯ Similarly, escape from cold (10 degrees C) was enhanced when preceded by escapable 44.5 degrees C stimulation. Thus, prior nociceptive stimulation enhanced escape from aversive thermal stimulation. Facilitation of pain by a preceding pain experience is consistent with stress-induced hyperalgesia and contrasts with other models of pain inhibition by concurrent nociceptive stimulation.
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Traditionally, pain is divided into two main groups: nociceptive pain due to an excess of nociception and neuropathic pain associated with an injury or dysfunction of the central or peripheral nervous system. The French neuropathic pain group has developed a specific questionnaire, the DN4, to help clinicians in the differential diagnosis of neuropathic and non-neuropathic pain. In order to allow this questionnaire to be used in international studies, it has been translated and linguistically validated into Dutch, German, Greek and Hungarian, using a well-established procedure. ⋯ The DN4 items were linguistically validated in each of the target languages, thus providing the means for standardising the diagnosis of neuropathic pain and pooling the data collected during clinical research in the different countries involved.
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Orofacial pain disorders are frequent in the general population and their pharmacological treatment is not always adequately resolved. Cannabinoids have demonstrated their analgesic effect in several pain conditions, both in animal models and in clinical situations. The aim of the present study was to evaluate the cannabinoid-mediated antinociception in two inflammatory models of orofacial pain (orofacial and temporomandibular joint (TMJ) formalin test) and to compare it with a spinal inflammatory model (paw formalin test). ⋯ Morphine displayed a dose-dependent reduction of acute and inflammatory pain in all three models, whereas indomethacin and ketamine only attenuated inflammatory pain at the highest tested doses. These results indicate that the cannabinoid-induced antinociception in the orofacial region is mediated by activation of CB1 cannabinoid receptor. Moreover WIN was as effective as morphine and more effective than indomethacin and ketamine, in oral inflammatory pain.
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The impact of pain beliefs on coping and adjustment is well established. However, less is known about how beliefs unrelated to pain might impact upon this experience. In particular, just world beliefs could impact upon and be influenced by chronic pain, given that pain is not experienced in a vacuum but instead is experienced in a social context where justice issues are potentially salient. ⋯ When interaction terms relating to personal and general just world beliefs were entered simultaneously into regression analyses, the personal just world belief did not predict psychological distress. However, pain intensity positively predicted psychological distress at low but not high levels of the general just world belief, while disability predicted psychological distress at low and high levels of this belief. This suggests that a strong general just world belief has implications for psychological well-being in chronic pain, and as such this belief may occupy a potential coping function in this context.