The journal of pain : official journal of the American Pain Society
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This study describes further development of the Multidimensional Pain Readiness to Change Questionnaire (MPRCQ2), a measure of readiness to adopt a variety of pain management and coping strategies commonly taught in multidisciplinary treatment programs. Clinical samples were recruited from a Fibromyalgia Day Program (n = 139) and an Arthritis Day Program (n = 51) as well as 2 survey samples with pain resulting from either a spinal cord injury (n = 127) or an amputation (n = 120). The results indicate preliminary support for the reliability and validity of the MPRCQ2. The MPRCQ2 may be helpful in future research investigating the relationship between readiness to change pain-related coping and adoption of coping behaviors and adjustment to chronic pain. ⋯ This study describes the development of a revised version of the MPRCQ, the MPRCQ2, in 4 patient samples. The results support the reliability and validity of the MPRCQ2 in individuals with fibromyalgia syndrome, arthritis, acquired amputation, and spinal cord injury and improve on some aspects of the instrument.
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Neuropathic pain is a major clinical problem, and several animal models have been developed to investigate its mechanisms and its treatment. In this report, the role of the rostral ventromedial medulla (RVM) in the early events of the chronic constriction injury (CCI) model was investigated in behavioral and electrophysiological experiments. Placing the 4 CCI ligatures around the sciatic nerve induced large discharges and residual ongoing activity in spinal nociceptive neurons. Two weeks after CCI ligation, the rats showed behavioral hyperalgesia and allodynia as well as increased ongoing activity and responsiveness of spinal nociceptive neurons to innocuous and noxious stimuli. Blockade of excitatory synapses in the RVM by a kynurenate microinjection (2 nmol in 0.5 muL) 5 minutes before placement of the sciatic ligatures had no immediate effect on spinal neuronal activity but largely prevented the activation of spinal neurons. In kynurenate microinjected rats, behavioral hyperalgesia and allodynia developed slowly and incompletely, which corresponded with an incompletely developed hyperexcitability of spinal neurons. To the best of our knowledge, these results show for the first time that the initial response to nerve damage requires facilitation from the RVM. ⋯ The present and previous findings indicate that descending facilitation from brainstem nuclei critically contributes to the spinal hyperexcitability that underlies neuropathic pain. The present results indicate that this contribution begins at the very moment the nerve is damaged and should be prevented and treated accordingly.
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Allodynia means that innocuous tactile stimulation is felt as pain. Accordingly, cerebral activations during allodynia or touch should markedly differ. The aim of this study was to investigate whether the imagination of allodynia affects brain processing of touch in healthy subjects. Seventeen healthy subjects divided into 2 subgroups were investigated: The first group (n = 7) was familiar with allodynia, based on previous pain studies, whereas the second group (n = 10) had never knowingly experienced allodynia. Using functional magnetic resonance imaging, 2 experimental conditions were investigated. In one condition the subjects were simply touched at their left hand, whereas during the other condition they were asked to imagine pain (allodynia) during tactile stimulation of the right hand and to estimate the imagined pain on a numeric rating scale. Data processing and analysis were performed with the use of SPM5. The group analysis of all subjects revealed that tactile stimulation activated contralateral somatosensory cortices (S1 [primary] and S2 [secondary]), but the imagination of allodynia led to an additional activation of anterior cingulate cortex and bilateral activation of S2, insular cortex, and prefrontal cortices. Subgroup analysis using rating-weighted predictors revealed activation of the contralateral thalamus, anterior cingulate cortex, and amygdala and a bilateral activation of S1, S2, and insular cortex and prefrontal cortices in allodynia-experienced subjects. In contrast, allodynia-inexperienced subjects only activated contralateral S1 and bilateral S2. Just the imagination that touch is painful is able to partly activate the central pain system, but only when the subject has previous experience of this. According to our results, the medial pain system is involved in the encoding of imagined allodynia. ⋯ This article reports that pain experience is able to alter central processing of sensory stimuli. Pain knowledge appears to be able to shift "normal" tactile processing to a different quality, resulting in modified brain activity. Therefore, our study may contribute to the current understanding of human pain and will promote future research on this field.
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The nonmedical use of prescription opioids (POs), and related harmful consequences, has increased in many populations in recent years in North America. Existing survey data are typically limited to descriptive prevalence statistics, and fail to examine important determinants or circumstances (including motives) of nonmedical PO use. We advocate that such analytical queries should become integral elements in future surveys. Developing the needed survey items, however, requires conceptual thoughtfulness and rigor, especially given POs' potential for both therapeutic (eg, analgesic) effects and abuse. These considerations are concretely relevant for possible "self-medicating" nonmedical usage of POs as well as with regards to varying definitions of "pain." Furthermore, we support the harmonization of survey items on nonmedical PO use to allow for cross-national comparisons, yet also call for cross-cultural examinations into the determinants of the currently vastly discrepant medical and nonmedical PO use rates across Western countries. ⋯ We support Zacny and Lichtor's call for systematic examination of motives presented by individuals engaging in nonmedical prescription opioid use. Such motives could relate to factors instrinsic or extrinsic to the user, yet their understanding is crucial for the devising of evidence-based interventions.
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Randomized Controlled Trial Clinical Trial
A randomized, placebo-controlled, crossover trial of cannabis cigarettes in neuropathic pain.
The Food and Drug Administration (FDA), Substance Abuse and Mental Health Services Administration (SAMHSA), and the National Institute for Drug Abuse (NIDA) report that no sound scientific studies support the medicinal use of cannabis. Despite this lack of scientific validation, many patients routinely use "medical marijuana," and in many cases this use is for pain related to nerve injury. We conducted a double-blinded, placebo-controlled, crossover study evaluating the analgesic efficacy of smoking cannabis for neuropathic pain. Thirty-eight patients with central and peripheral neuropathic pain underwent a standardized procedure for smoking either high-dose (7%), low-dose (3.5%), or placebo cannabis. In addition to the primary outcome of pain intensity, secondary outcome measures included evoked pain using heat-pain threshold, sensitivity to light touch, psychoactive side effects, and neuropsychological performance. A mixed linear model demonstrated an analgesic response to smoking cannabis. No effect on evoked pain was seen. Psychoactive effects were minimal and well-tolerated, with some acute cognitive effects, particularly with memory, at higher doses. ⋯ This study adds to a growing body of evidence that cannabis may be effective at ameliorating neuropathic pain, and may be an alternative for patients who do not respond to, or cannot tolerate, other drugs. However, the use of marijuana as medicine may be limited by its method of administration (smoking) and modest acute cognitive effects, particularly at higher doses.