Articles: neuralgia.
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Neuropathic pain is a common complication of treatment with the anti-neoplastic drug paclitaxel. Animal studies suggest neuroinflammation and transient receptor potential channels TRPA1 and TRPV4 are involved in the pathogenesis of pain in this condition. However, how neuroinflammation and TRPA1 and TRPV4 are linked to cause pain in paclitaxel-treated animals is not known. ⋯ These results suggest that paclitaxel activation of TLR-4 to cause release of TNF-α from satellite glial cells increases the expression of TRPA1 and TRPV4 in DRG neurons to cause neuropathic pain.
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Increased apoptotic changes in the spinal cord may be responsible for the development of chronic constriction injury (CCI)-induced neuropathic pain. We previously reported the beneficial effect of hyperbaric oxygen (HBO) in the treatment of CCI-induced neuropathic pain. In this study, we tested our hypotheses that HBO may achieve its beneficial effect by inhibiting CCI-induced proapoptosis gene expression and apoptosis in the spinal cord. ⋯ Overly expressed proapoptosis genes, and subsequent increase in spinal apoptotic cells, seem to contribute to the development of CCI-induced neuropathic pain. The inhibitory role of HBO on spinal proapoptosis genes and apoptotic changes may contribute to its beneficial effect on CCI-induced neuropathic pain.
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To determine if medical marijuana provides pain relief for patients with chronic noncancer pain (CNCP) and to determine the therapeutic dose, adverse effects, and specific indications. ⋯ There is evidence for the use of low-dose medical marijuana in refractory neuropathic pain in conjunction with traditional analgesics. However, trials were limited by short duration, variability in dosing and strength of delta-9-tetrahydrocannabinol, and lack of functional outcomes. Although well tolerated in the short term, the long-term effects of psychoactive and neurocognitive effects of medical marijuana remain unknown. Generalizing the use of medical marijuana to all CNCP conditions does not appear to be supported by existing evidence. Clinicians should exercise caution when prescribing medical marijuana for patients, especially in those with nonneuropathic CNCP.
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Review
Neuropathic pain screening questionnaires have limited measurement properties. A systematic review.
The Douleur Neuropathique 4 (DN4), ID Pain, Leeds Assessment of Neuropathic Symptoms and Signs (LANSS), PainDETECT, and Neuropathic Pain Questionnaire have been recommended as screening questionnaires for neuropathic pain. This systematic review aimed to evaluate the measurement properties (eg, criterion validity and reliability) of these questionnaires. ⋯ Overall, the DN4 and Neuropathic Pain Questionnaire were most suitable for clinical use. These screening questionnaires should not replace a thorough clinical assessment.
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Randomized Controlled Trial
A More Pessimistic Life Orientation Is Associated With Experimental Inducibility of a Neuropathy-like Pain Pattern in Healthy Individuals.
The clinical pattern of neuropathic pain, diagnosed using the quantitative sensory testing (QST) battery (German Research Network on Neuropathic Pain), could be partly mimicked in healthy volunteers after topical capsaicin application. However, similar to clinical neuropathic pain that develops in only a subgroup of patients who have a neurologic lesion, this attempt to mimick a neuropathic pain pattern succeeded only in a small fraction (18%) of healthy individuals. In the present assessment, we pursued the hypothesis that the inducible subgroup differed from the other healthy participants with respect to their psychological phenotype. Therefore, in an observational study, participants were assessed using a comprehensive set of psychological variables comprising general psychological and pain-related cognitive-emotional mechanisms. The sum scores of the questionnaires were significantly linearly correlated with each other. Principal component analysis indicated that a major source of variance (46%) could be attributed to dispositional optimism examined via the Life Orientation Test (LOT). The LOT score significantly differed between the groups of participants, either those in whom a neuropathy-like pattern of pain assessed via QST could be partly (50-60% of the 11 QST parameters) induced (n = 20) or not (n = 90; P = .0375). It emerged again as the main selection criterion in a classification and regression tree predicting a participant's group assignment (inducible neuropathy-like QST pattern versus noninducible neuropathy-like QST pattern) at a cross-validated accuracy of 95.5 ± 2.1%. Thus, the few participants in a random sample of healthy volunteers who, after topical capsaicin application, partly resemble (to a degree of about 60%) the clinical pattern of neuropathic pain in the QST test battery, are preselectable on the basis of psychological factors, with a particular emphasis on pessimistic life attitudes. ⋯ In a small fraction of 18% of healthy volunteers, topical capsaicin application resulted in a neuropathy-like pattern in 50 to 60% of the components of a clinical test battery. These individuals displayed a more pessimistic life attitude as assessed by means of the LOT.