The journal of pain : official journal of the American Pain Society
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Review Meta Analysis
Conditioned pain modulation and temporal summation of pain in patients with traumatic and non-specific neck pain: a systematic review and meta-analysis.
In patients with neck pain, it is unclear whether pain inhibition and facilitation endogenous pain mechanisms are altered. This systematic review and meta-analysis aimed to improve their understanding by assessing conditioned pain modulation (CPM) and temporal summation of pain (TSP) in patients with neck pain associated with whiplash-associated disorders (WAD) or of a nonspecific neck pain (NSNP) nature compared to pain-free controls. Very low certainty evidence suggests: impaired CPM when assessed remotely in chronic WAD patients (n = 7, 230 patients and 204 controls, standardized mean differences (SMD) = -.47 [-.89 to -.04]; P = .04) but not locally (n = 6, 155 patients and 150 controls; SMD = -.34 [-.68 to .01]; P = .05), impaired CPM in chronic NSNP patients when assessed locally (n = 5, 223 patients and 162 controls; SMD = -.55 [-1.04 to -.06]; P = .04) but not remotely (n = 3, 72 patients and 66 controls; SMD = -.33 [-.92 to .25]; P = .13), TSP not facilitated in either chronic WAD (local TSP: n = 4, 90 patients and 87 controls; SMD = .68 [-.62 to 1.99]) (remote TSP: n = 8, 254 patients and 214 controls; SMD = .18 [-.12 to .48]) or chronic NSNP (local TSP: n = 2, 139 patients and 92 controls; SMD = .21 [-1.00 to 1.41]), (remote TSP: n = 3; 91 patients and 352 controls; SMD = .60 [-1.33 to 2.52]). ⋯ PERSPECTIVE: This review and meta-analysis present the current evidence on CPM and TSP in patients with WAD and NSNP. Standardization of measurement methodology is needed to draw clear conclusions. Subsequently, future studies should investigate the clinical relevance of these measurements as prognostic variables or predictors of treatment success.
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Meta Analysis
Characterisation of common genetic variants in P2RX7 and their contribution to chronic pain conditions.
The adenosine triphosphate (ATP)-gated channel P2X7 is encoded by a gene enriched for common nonsynonymous variants. Many of these variants have functional cellular effects, and some have been implicated in chronic pain. In this study, we first systematically characterized all 17 common nonsynonymous variants using whole-cell patch clamp electrophysiology. ⋯ Cumulative allele count analysis did not provide additional insights. In conclusion, our results go beyond reproducing association for rs7958311 with chronic pain and suggest that its unique combination of gain-of-function in channel and loss-of-function in pore activity may explain why it is likely the only common P2RX7 variant with contribution to chronic pain. PERSPECTIVE: This study characterizes all common P2RX7 variants using cellular assays and statistical association analyses with chronic pain, with Markov state modeling of the most robustly associated variant.
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Randomized Controlled Trial
Efficacy of home-based transcranial direct current stimulation over the primary motor cortex and dorsolateral prefrontal cortex in the disability due to pain in fibromyalgia: A factorial sham-randomized clinical study.
This randomized, double-blind, controlled clinical trial compared the effectiveness of home-based-(HB) active transcranial direct current stimulation (a-tDCS) over the left dorsolateral prefrontal cortex (l-DLPFC) or primary motor cortex (M1) with their respective sham-(s)-tDCS to determine whether a-tDCS would be more effective than s-tDCS in reducing pain and improving disability due to pain. The study included 102 patients with fibromyalgia aged 30 to 65 years old randomly assigned to 1 of 4 tDCS groups using a ratio of 2:1:2:1. The groups included l-DLPFC (a-tDCS, n = 34) and (s-tDCS, n = 17), or tDCS on the M1 (a-tDCS, n = 34) or (s-tDCS, n = 17). ⋯ PERSPECTIVE: These findings provide important insights: (1) HB-tDCS has effectively reduced pain scores and improved disability due to fibromyalgia. (2) The study provides evidence that HB-a-tDCS is a viable and effective therapeutic approach. (3) HB-a-tDCS over M1 improved the function of the descending pain inhibitory system and increased the heat pain threshold. Finally, our findings also emphasize that brain-derived neurotrophic factor, as an index of neuroplasticity, may serve as a valuable marker associated with changes in clinical pain measures. TRIAL REGISTRATION: Number NCT03843203.
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We aim to present the first psychometric evaluation of the Performance-related Pain Among Musicians questionnaire (PPAM), the first questionnaire specifically designed to evaluate performance-related pain among musicians with different musical backgrounds, based on a multicenter validation study. The psychometric evaluation was performed in a validation sample of 458 musicians, at baseline and after seven days. We assessed the applicability, reliability, internal consistency, construct validity, and factor structure of the PPAM. ⋯ It will allow the development of more robust studies on pain and disability among musicians, comparative studies between different subgroups of musicians and the evaluation of predictive factors of pain development. PERSPECTIVE: This article presents the psychometric properties of the first questionnaire to evaluate pain among musicians (in general), the "Performance-related Pain among Musicians Questionnaire" (PPAM). This valid and reliable tool, composed by three constructs (pain intensity, interference in general activities, and interference in performance), will improve the pain assessment among musicians.
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This prospective cohort study investigates the prognosis of patients with neuropathic low back-related leg pain consulting in UK primary care. Data from 511 patients were collected using standardised baseline clinical examinations (including magnetic resonance imaging scan findings), self-report questionnaires at baseline, 4 months, 12 months, and 3 years. Cases of possible neuropathic pain (NP) and persistent-NP were identified using either of 2 definitions: 1) clinical diagnosis of sciatica, 2) self-report version of leeds assessment for neurological symptoms and signs (s-LANSS). ⋯ PERSPECTIVE: This study provides evidence that neuropathic back-related leg pain in patients consulting in primary care is not always persistent. Patients with persistent neuropathic pain had worse outcomes than those without. Neither leg pain intensity, pain self-efficacy nor MRI scan findings predicted cases of persistent neuropathic pain in this patient population.