Articles: neuropathic-pain.
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As an indirect approach to relate previously identified sensory phenotypes of patients suffering from peripheral neuropathic pain to underlying mechanisms, we used a published sorting algorithm to estimate the prevalence of denervation, peripheral and central sensitization in 657 healthy subjects undergoing experimental models of nerve block (NB) (compression block and topical lidocaine), primary hyperalgesia (PH) (sunburn and topical capsaicin), or secondary hyperalgesia (intradermal capsaicin and electrical high-frequency stimulation), and in 902 patients suffering from neuropathic pain. Some of the data have been previously published. Randomized split-half analysis verified a good concordance with a priori mechanistic sensory profile assignment in the training (79%, Cohen κ = 0.54, n = 265) and the test set (81%, Cohen κ = 0.56, n = 279). ⋯ Topical menthol was the only model with significant cold hyperalgesia. Sorting of the 902 patients into these mechanistic phenotypes led to a similar distribution as the original heuristic clustering (65% identity, Cohen κ = 0.44), but the denervation phenotype was more frequent than in heuristic clustering. These data suggest that sorting according to human surrogate models may be useful for mechanism-based stratification of neuropathic pain patients for future clinical trials, as encouraged by the European Medicines Agency.
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Chronic abdominal pain is occasionally due to entrapped intercostal nerve endings (ACNES, abdominal cutaneous nerve entrapment syndrome). If abdominal wall infiltration using an anesthetic agent is unsuccessful, a neurectomy may be considered. Pulsed radiofrequency (PRF) is a relatively new treatment option for various chronic pain syndromes. Evidence regarding a beneficial effect of this minimally invasive technique in ACNES is lacking. The aim was to assess the effectiveness of PRF treatment in ACNES patients. ⋯ PRF is temporarily effective in half of patients with ACNES. PRF is safe and may be favored in neuropathic pain syndromes as nerve tissue destruction is possibly limited. A randomized controlled trial determining the potential additional role of PRF in the treatment strategy for ACNES is underway.
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Persistent mild traumatic brain injury related headache (MTBI-HA) represents a neuropathic pain state. This study tested the hypothesis that repetitive transcranial magnetic stimulation (rTMS) at the left prefrontal cortex can alleviate MTBI-HA and associated neuropsychological dysfunctions. ⋯ A short-course rTMS at the left DLPFC can alleviate MTBI-HA symptoms and provide a transient mood enhancing benefit. Further studies are required to establish a clinical protocol balancing both treatment efficacy and patient compliance.
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Complex regional pain syndrome (CRPS) is a complex pain disorder that can emerge after limb trauma or a lesion in the peripheral nervous system. Typical features include continuing pain, sensory, vasomotor, sudomotor, motor, and trophic changes as well as edema. These signs provide the basis of CRPS diagnosis. ⋯ We identified 11 distinct etiological triggers, which cover more than 99% of the study participants. We developed a weighted score on the basis of the most decisive data, which achieved a sensitivity of .869 and a specificity of .829, compared with .819 and .679 for the Budapest criteria. The weighted diagnostic criteria may help to better aid in distinguishing CRPS from other pain disorders.
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Vincristine is a commonly used chemotherapeutic drug that can produce painful peripheral neuropathy. The chemokine (C-X-C motif) ligand 1 (CXCL1) and its receptor chemokine (C-X-C motif) receptor 2 (CXCR2) may mediate the resolution of this inflammation. In this study, we investigated whether and how CXCL1 contributes to vincristine-induced pain and the underlying mechanisms of levo-corydalmine (l-CDL, a tetrahydroprotoberberine). ⋯ In primary neurons, l-CDL indirectly reduced an increase in CXCR2 by astrocyte-conditioned medium but did not act directly on the CXCR2 site. Taken together, our data first demonstrate that an NFκB-dependent CXCL1/CXCR2 signaling pathway is involved in vincristine-induced neuropathic pain. In addition, the present findings suggest that l-CDL likely attenuates this inflammation through down-regulation of this signaling pathway.