Quantitative sensory testing in migraine patients must be phase-specific
No abstract available (Source: Pain)
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Correspondence Source Type: research

Long-term changes in biopsychosocial characteristics related to temporomandibular disorder: findings from the OPPERA study
Painful temporomandibular disorders (TMDs) are both consequence and cause of change in multiple clinical, psychosocial, and biological factors. Although longitudinal studies have identified antecedent biopsychosocial factors that increase risk of the TMD onset and persistence, little is known about long-term change in those factors after TMD develops or remits. During a 7.6-year median follow-up period, we measured change in psychosocial characteristics, pain sensitivity, cardiovascular indicators of autonomic function, and clinical jaw function among 189 participants whose baseline chronic TMD status either persisted or r...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Prevalence of chronic pain with or without neuropathic characteristics in France using the capture–recapture method: a population-based study
This study sought to provide up-to-date estimates of the prevalence of people experiencing CP ± neuropathic characteristics in France using the capture–recapture method. In 2013 to 2015, 3 data sources were used: the French prescription drug database (D-list), the national hospital discharge database (H-list), and the French pain center database (P-list). Patients aged 18 years and older treated with analgesic drugs for ≥6 months (D-list) or with a diagnosis of CP ± neuropathic characteristics (H- and P-lists) were included. Two successive capture–recapture analyses were conducted, with log-lin...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Inflammation induces Epac-protein kinase C alpha and epsilon signaling in TRPV1-mediated hyperalgesia
The exchange proteins activated by cAMP (Epacs) have been shown to play important roles in producing inflammation-induced nociception. Transient receptor potential vanilloid type 1 (TRPV1) is a major receptor processing thermal and chemosensitive nociceptive information. The role of Epacs in modulating the activity of TRPV1 has yet to be determined. Studying the effect of complete Freund adjuvant (CFA)-induced inflammation on capsaicin-activated TRPV1 nociceptive responses in dorsal root ganglia (DRG), we found that CFA produced a large increase in capsaicin-induced responses. The increase was inhibited by Epac1 and Epac2 ...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Quantifying visual allodynia across migraine subtypes: the Leiden Visual Sensitivity Scale
Enhanced sensitivity to light (photophobia) and patterns is common in migraine and can be regarded as visual allodynia. We aimed to develop and validate a questionnaire to easily quantify sensitivity to light and patterns in large populations, and to assess and compare visual allodynia across different migraine subtypes and states. We developed the Leiden Visual Sensitivity Scale (L-VISS), a 9-item scale (score range 0-36 points), based on literature and patient interviews, and examined its construct validity. Furthermore, we assessed ictal and interictal visual sensitivity in episodic migraine with (n = 67) and without (n...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Contextual influences in decoding pain expressions: effects of patient age, informational priming, and observer characteristics
We aimed to examine the effects of contextual factors (ie, observers' training background and priming texts) on decoding facial pain expressions of younger and older adults. A total of 165 participants (82 nursing students and 83 nonhealth professionals) were randomly assigned to one of 3 priming conditions: (1) information about the possibility of secondary gain (misuse); (2) information about the frequency and undertreatment of pain in the older adult (undertreatment); or (3) neutral information (control). Subsequently, participants viewed 8 videos of older adults and 8 videos of younger adults undergoing a discomforting...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Isolated nociceptors reveal multiple specializations for generating irregular ongoing activity associated with ongoing pain
Ongoing pain has been linked to ongoing activity (OA) in human C-fiber nociceptors, but rodent models of pain-related OA have concentrated on allodynia rather than ongoing pain, and on OA generated in non-nociceptive Aβ fibers rather than C-fiber nociceptors. Little is known about how ongoing pain or nociceptor OA is generated. To define neurophysiological alterations underlying nociceptor OA, we have used isolated dorsal root ganglion neurons that continue to generate OA after removal from animals displaying ongoing pain. We subclassify OA as either spontaneous activity generated solely by alterations intrinsic to th...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Neuropathic pain clinical trials: factors associated with decreases in estimated drug efficacy
This study is a secondary analysis of data from a previous published NeuPSIG systematic review and meta-analysis, updated to include studies published up till March 2017. We included double-blind, randomized, placebo-controlled trials examining the effect of drugs for which we had made strong or weak recommendations for use in neuropathic pain in the previously published review. As the primary outcome, we used an aggregated number needed to treat for 50% pain reduction (alternatively 30% pain reduction or moderate pain relief). Analyses involved 128 trials. Number needed to treat values increased from around 2 to 4 in tria...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Aδ and not C fibers mediate thermal hyperalgesia to short laser stimuli after burn injury in man
It remains unclear which nerve fibers are responsible for mediating hyperalgesia after skin injury. Here, we examined the role of Aδ and C fibers in inflammatory hyperalgesia after a first-degree burn injury. A CO2 laser delivered ultrafast short constant-temperature heat pulses to the upper part of the lower leg to stimulate selectively the relatively fast-conducting thinly myelinated Aδ and the slowly conducting unmyelinated C fibers. Participants were asked to respond as fast as possible whenever they detected a thermal stimulus. Thresholds and reaction times to selective Aδ and C fiber activations wer...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Electrophysiological characterisation of central sensitisation in canine spontaneous osteoarthritis
In man, central sensitisation (CS) contributes to the pain of osteoarthritis (OA). Dogs with spontaneous OA may also exhibit CS. Electrophysiological reflex measurements are more objective than behavioural assessments and can be used to evaluate CS in preclinical and clinical studies. It was hypothesised that dogs suffering from OA would exhibit electrophysiological characteristics indicative of CS, associated with reduced diffuse noxious inhibitory controls (DNICs). One hundred and seventeen client-owned dogs were recruited to the study. Hind limb nociceptive withdrawal reflex thresholds, stimulus response, and temporal s...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Peripherally administered calcitonin gene–related peptide induces spontaneous pain in mice: implications for migraine
In this study, we report that peripherally administered CGRP can act in a light-independent manner to produce spontaneous pain in mice that is manifested as a facial grimace. As an objective validation of the orbital tightening action unit of the grimace response, we developed a squint assay using a video-based measurement of the eyelid fissure, which confirmed a significant squint response after CGRP injection, both in complete darkness and very bright light. These indicators of discomfort were completely blocked by preadministration of a monoclonal anti-CGRP–blocking antibody. However, the nonsteroidal anti-inflamm...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Complex regional pain syndrome: intradermal injection of phenylephrine evokes pain and hyperalgesia in a subgroup of patients with upregulated α1-adrenoceptors on dermal nerves
The aim of this study was to determine whether upregulated cutaneous expression of α1-adrenoceptors (α1-AR) is a source of pain in patients with complex regional pain syndrome (CRPS). Immunohistochemistry was used to identify α1-AR on nerve fibres and other targets in the affected and contralateral skin of 90 patients, and in skin samples from 38 pain-free controls. The distribution of α1-AR was compared between patients and controls, and among subgroups of patients defined by CRPS duration, limb temperature asymmetry, and diagnostic subtype (CRPS I vs CRPS II). In addition, α1-AR expression w...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Anti–nerve growth factor does not change physical activity in normal young or aging mice but does increase activity in mice with skeletal pain
Anti–nerve growth factor (anti-NGF) therapy has shown significant promise in attenuating several types of skeletal pain. However, whether anti-NGF therapy changes the level of physical activity in individuals with or without skeletal pain is largely unknown. Here, automated day/night activity boxes monitored the effects of anti-NGF treatment on physical activity in normal young (3 months old) and aging (18-23 months old) mice and mice with bone fracture pain. Although aging mice were clearly less active and showed loss of bone mass compared with young mice, anti-NGF treatment had no effect on any measure of day/night...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Analgesic effects of a novel pH-dependent μ-opioid receptor agonist in models of neuropathic and abdominal pain
Recently, (±)-N-(3-fluoro-1-phenethylpiperidine-4-yl)-N-phenyl propionamide (NFEPP), a newly designed μ-opioid receptor (MOR) agonist with a low pKa, has been shown to produce injury-restricted analgesia in models of inflammatory and postoperative pain, without exhibiting typical opioid side effects. Here, we investigated MOR binding of NFEPP in brain and dorsal root ganglia, pH in injured tissues, and the analgesic efficacy of NFEPP compared with fentanyl in a chronic constriction injury model of neuropathic pain, and in the acetic acid–induced abdominal writhing assay in rats. Binding experiments revealed...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Dynamic pain connectome functional connectivity and oscillations reflect multiple sclerosis pain
Pain is a prevalent and debilitating symptom of multiple sclerosis (MS); yet, the mechanisms underlying this pain are unknown. Previous studies have found that the functional relationships between the salience network (SN), specifically the right temporoparietal junction a SN node, and other components of the dynamic pain connectome (default mode network [DMN], ascending and descending pathways) are abnormal in many chronic pain conditions. Here, we use resting-state functional magnetic resonance imaging and measures of static and dynamic functional connectivity (sFC and dFC), and regional BOLD variability to test the hypo...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Lionfish venom elicits pain predominantly through the activation of nonpeptidergic nociceptors
In this study, we provide the first characterization of the pain and inflammation caused by lionfish venom and examine the mechanisms through which it causes pain using a combination of in vivo and in vitro approaches including behavioral, physiological, calcium imaging, and electrophysiological testing. Intraplantar injections of the venom produce a significant increase in pain behavior, as well as a marked increase in mechanical sensitivity for up to 24 hours after injection. The algogenic substance(s) are heat-labile peptides that cause neurogenic inflammation at the site of injection and induction of Fos and microglia ...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Evaluation of composite responder outcomes of pain intensity and physical function in neuropathic pain clinical trials: an ACTTION individual patient data analysis
Integrating information on physical function and pain intensity into a composite measure may provide a useful method for assessing treatment efficacy in clinical trials of chronic pain. Accordingly, we evaluated composite outcomes in trials of duloxetine, gabapentin, and pregabalin. Data on 2287 patients in 9 trials for painful diabetic peripheral neuropathy (DPN) and 1513 patients in 6 trials for postherpetic neuralgia (PHN) were analyzed. All trials assessed pain intensity on a 0 to 10 numeric rating scale and physical function with the 10-item subscale of the Short Form-36, ranging 0 to 100 with higher scores indicating...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Estimating relative efficacy in acute postoperative pain: network meta-analysis is consistent with indirect comparison to placebo alone
Network meta-analysis uses direct comparisons of interventions within randomized controlled trials and indirect comparisons across them. Network meta-analysis uses more data than a series of direct comparisons with placebo, and theoretically should produce more reliable results. We used a Cochrane overview review of acute postoperative pain trials and other systematic reviews to provide data to test this hypothesis. Some 261 trials published between 1966 and 2016 included 39,753 patients examining 52 active drug and dose combinations (27,726 given active drug and 12,027 placebo), in any type of surgery (72% dental). Most t...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Efficacy of adding interoceptive exposure to intensive interdisciplinary treatment for adolescents with chronic pain: a randomized controlled trial
In conclusion, the results suggest that IE is not particularly effective for all the pediatric chronic pain patients, but the patients with high fear of pain before treatment and with abdominal pain strongly benefit from this intervention. (Source: Pain)
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Low- and high-threshold primary afferent inputs to spinal lamina III antenna-type neurons
The dorsal horn of the spinal cord (laminae I-VI) processes diverse modalities of nociceptive and nonnociceptive sensory information. Antenna-type neurons with cell bodies located in lamina III and large dendritic trees extending from the superficial lamina I to deep lamina IV are best shaped for the integration of a wide variety of inputs arising from primary afferent fibers and intrinsic spinal circuitries. Although the somatodendritic morphology, the hallmark of antenna neurons, has been well studied, little is still known about the axon structure and basic physiological properties of these cells. Here, we did whole-cel...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Chronic itch impairs mood and HPA axis function in mice: modulation by CRFR1 antagonist
Chronic itch is clinically correlated with the development of mood disorders such as anxiety and depression. Nonetheless, whether this relevance exists in rodents is unknown, and evidence demonstrating chronic itch can affect mood is lacking. The aim of this study is to characterize the affective consequences of chronic itch, and explore potential mechanisms and interventional strategy. We subjected mice to chronic itch by repetitive cutaneous treatment with acetone and diethylether followed by water (AEW) that models “dry skin.” After 3 to 4 weeks AEW treatment, the mice developed behavioral phenotypes of anxi...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Location-specific responses to nociceptive input support the purposeful nature of motor adaptation to pain
This study addressed this question using high-density electromyography (EMG) to study regional redistribution of muscle activation within the vasti muscles and changes in knee extension force direction in response to noxious stimulation applied to muscular and nonmuscular tissues around the knee. Fourteen participants performed a low-force knee extension contraction at baseline, during, and after pain induced in 4 locations (infrapatellar fat pad, vastus lateralis, distal vastus medialis, or proximal vastus medialis). The knee extension force direction was estimated from a 3-dimensional load cell positioned just above the ...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Influence of neuropathic pain on nicotinic acetylcholine receptor plasticity and behavioral responses to nicotine in rats
Tobacco smoking is particularly evident in individuals experiencing chronic pain. This complex relationship is poorly understood at both molecular and behavioral levels. Here, we describe experiments aimed at understanding whether a chronic pain state induces neuroadaptations into the brain or peripheral nerves that involve nicotinic acetylcholine receptors (nAChRs) and whether these neuroadaptations directly lead to increased vulnerability to nicotine addiction or to the development of coping strategies to relieve pain symptoms. We found that ligation of the rat L5 spinal nerve led to a dramatic downregulation in the mRNA...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Involvement of lysophosphatidic acid–induced astrocyte activation underlying the maintenance of partial sciatic nerve injury–induced neuropathic pain
We have previously demonstrated that lysophosphatidic acid (LPA) plays key roles in the initial mechanisms for neuropathic pain (NeuP) development. Here, we examined whether LPA receptor mechanisms and LPA production are related to the glial activation at a late stage after partial sciatic nerve ligation (pSNL) by use of microglial inhibitor, Mac1-saporin or astrocyte inhibitor, and L-α-aminoadipate (L-AA). Although single intrathecal injection of LPA1/3 antagonist, Ki-16425 did not affect the pain threshold at day 7 after the spinal cord injury, repeated treatments of each compound gradually reversed the basal pain ...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Do post-traumatic pain and post-traumatic stress symptomatology mutually maintain each other? A systematic review of cross-lagged studies
In conclusion, the findings suggest an entangled, but not necessarily mutually maintaining relationship between pain and PTSD symptomatology. However, major variations in findings and methodologies complicated synthesis, prompting careful interpretation and heightening the likelihood that future high-quality studies will change these conclusions. (Source: Pain)
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Systematic Review and Meta-Analysis Source Type: research

Twenty-five years of pain education research—what have we learned? Findings from a comprehensive scoping review of research into pre-registration pain education for health professionals
This article reports on a synthesis of pain education research that has been conducted in this period of health professionals' training. A scoping review framework by Arksey and O'Malley was used to guide a search of medical and education databases for records that have examined or evaluated pain education. Fifty-six reports were identified representing 16 professions across 29 countries, published between 1992 and 2017. A descriptive account of the reports is provided, which includes a timeline, geography, methods of evaluating, and main purpose of the research. A narrative synthesis was undertaken to summarise and explai...
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Narrative Review Source Type: research

Depression in chronic pain: might opioids be responsible?
No abstract available (Source: Pain)
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Topical Review Source Type: research

Conceptual complexity of gender and its relevance to pain
No abstract available (Source: Pain)
Source: Pain - October 25, 2018 Category: Anesthesiology Tags: Topical Review Source Type: research

What do clinicians consider when assessing chronic low back pain? A content analysis of multidisciplinary pain centre team assessments of functioning, disability, and health
This study sought to map the content of MPC clinical assessments to the ICF to: (1) identify and compare the content of clinical MDT assessments using a cross-disciplinary framework and (2) examine the content validity of the LBP-CS. A qualitative examination of MPC team clinical assessments of chronic low back pain was undertaken. Multidisciplinary team (pain medicine, psychiatry, nursing, physiotherapy, occupational therapy, and psychology) assessments were audio-recorded and transcribed. Concepts were extracted from transcripts using a meaning condensation procedure and then linked to the ICF. Across 7 MDT assessments, ...
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Clinical Note Source Type: research

Inhibition of the Ubc9 E2 SUMO-conjugating enzyme–CRMP2 interaction decreases NaV1.7 currents and reverses experimental neuropathic pain
We previously reported that destruction of the small ubiquitin-like modifier (SUMO) modification site in the axonal collapsin response mediator protein 2 (CRMP2) was sufficient to selectively decrease trafficking of the voltage-gated sodium channel NaV1.7 and reverse neuropathic pain. Here, we further interrogate the biophysical nature of the interaction between CRMP2 and the SUMOylation machinery, and test the hypothesis that a rationally designed CRMP2 SUMOylation motif (CSM) peptide can interrupt E2 SUMO-conjugating enzyme Ubc9-dependent modification of CRMP2 leading to a similar suppression of NaV1.7 currents. Microsca...
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Long-term pain relief in canine osteoarthritis by a single intra-articular injection of resiniferatoxin, a potent TRPV1 agonist
We report on a peripheral interventional approach that uses intra-articular injection of the ultrapotent TRPV1 agonist resiniferatoxin (RTX) to produce a selective long-term chemoinactivation of nociceptive primary afferent nerve endings for pain control in naturally occurring canine osteoarthritis. A single injection of 10 µg of RTX, produced suppression of pain, improvement in gait, weight bearing, and improvement in the dog's activities of daily living lasting 4 months or longer. Two to 3 years after the injection, there are no alterations to suggest that removal of inflammatory pain caused accelerated joint degen...
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Changes in pain intensity after discontinuation of long-term opioid therapy for chronic noncancer pain
The objective of this study was to characterize pain intensity after opioid discontinuation over 12 months. This retrospective U.S. Department of Veterans Affairs (VA) administrative data study identified N = 551 patients nationally who discontinued LTOT. Data over 24 months (12 months before and after discontinuation) were abstracted from VA administrative records. Random-effects regression analyses examined changes in 0 to 10 pain numeric rating scale scores over time, whereas growth mixture models delineated pain trajectory subgroups. Mean estimated pain at the time of opioid discontinuation was 4.9. Changes in pain aft...
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Patterns of recovery from pain after cesarean delivery
We know very little about the change in pain in the first 2 months after surgery. To address this gap, we studied 530 women scheduled for elective cesarean delivery who completed daily pain diaries for 2 months after surgery through text messaging. Over 82% of subjects missed fewer than 10 diary entries and were included in the analysis. Completers were more likely to be Caucasian, nonsmokers, and with fewer previous pregnancies than noncompleters. Daily worst pain intensity ratings for the previous 24 hours were fit to a log(time) function and allowed to change to a different function up to 3 times according to a Bayesian...
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Multivariate pattern classification of brain white matter connectivity predicts classic trigeminal neuralgia
This study demonstrates that machine-learning algorithms can detect characteristic patterns of structural alterations in TN and highlights the role of structural brain imaging for identification of neuroanatomical features associated with neuropathic pain disorders. (Source: Pain)
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Mixed-methods development of a new patient-reported outcome instrument for chronic low back pain: part 2—The Patient Assessment for Low Back Pain–Impacts (PAL-I)
We describe qualitative and quantitative development and preliminary validation of the Patient Assessment for Low Back Pain–Impacts (PAL-I), a patient-reported outcome measure for use in chronic low back pain (cLBP) clinical trials. Concept elicitation and cognitive interviews (qualitative methods) were used to identify and refine symptom concepts. Classical test theory and Rasch measurement theory (quantitative methods) were used to evaluate item-level and scale-level performance of the PAL-I using an iterative approach between qualitative and quantitative methods. Patients with cLBP participated in concept elicitat...
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Dynamic sodium imaging at ultra-high field reveals progression in a preclinical migraine model
Under the hypothesis that increased extracellular sodium induces sustained neuronal excitability with the onset and progression of migraine, this study evaluates dynamic in vivo 23Na fluxes in the brain of a preclinical rodent analogue of migraine. Ultra-high field 23Na magnetic resonance imaging (MRI) at 21.1 T has demonstrated potential to quantify sodium concentrations with good spatial and temporal resolution after the onset of central sensitization. Sprague-Dawley male rats with implanted intraperitoneal lines were studied by MRI before and after an in situ injection of 10 mg/kg of nitroglycerin (NTG) vs vehicle and s...
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Racial differences in opioid prescribing for children in the United States
We examined racial and ethnic differences in outpatient analgesic prescribing using nationally representative data from 113,929 children from the Medical Expenditure Panel Survey. We also examined whether patient–provider race and ethnic concordance was associated with opioid prescription. White children were more commonly prescribed opioids as compared to minorities (3.0% vs 0.9%-1.7%), except for Native American children who had similar rates of opioid prescription (2.6%) as white children. Minorities were more likely to receive nonopioid analgesics than white children (2.0%-5.7% vs 1.3%). Although most white child...
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Cultural influences on parental responses to children's pain
There is a scarcity of work examining the relationship between culture and pain-related caregiver behaviors. Moreover, no pediatric pain studies have examined the relationship between caregiver cultural values and pain-related caregiver behaviors nor discern if this process is mediated by caregiver parenting styles and moderated by ecosocial context. Based on cross-cultural developmental theories, this study hypothesized that ecosocial context would moderate the relationship between cultural values, parenting styles, and pain-related caregiver behaviors; and that parenting styles mediate the effect of cultural values on pa...
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Color-selective photophobia in ictal vs interictal migraineurs and in healthy controls
This study aimed at determining whether these findings are phase-dependent–namely, manifested exclusively during migraine (ictally) but not in its absence (interictally), or condition-dependent—ie, expressed uniquely in migraineurs but not in healthy controls. To determine whether the color preference of migraine-type photophobia is phase- or condition-dependent, we compared the effects of each color of light in each intensity between migraineurs during and in-between attacks and healthy controls. During the ictal and interictal phases, the proportion of migraineurs reporting changes in headache severity when e...
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Dermal nerve fibre and mast cell density, and proximity of mast cells to nerve fibres in the skin of patients with complex regional pain syndrome
An interaction between cutaneous nerves and mast cells may contribute to pain in complex regional pain syndrome (CRPS). To explore this, we investigated the density of dermal nerve fibres, and the density and proximity of mast cells to nerve fibres, in skin biopsies obtained from the affected and unaffected limbs of 57 patients with CRPS and 28 site-matched healthy controls. The percentage of the dermis stained by the pan-neuronal marker protein gene-product 9.5 was lower in the affected limb of patients than in controls (0.12 ± 0.01% vs 0.22 ± 0.04%, P (Source: Pain)
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Pain processing in the human brainstem and spinal cord before, during, and after the application of noxious heat stimuli
Descending regulation of spinal cord responses to nociceptive signaling has a strong influence on pain perception. Previous studies using functional magnetic resonance imaging (fMRI) have indicated that in addition to reactive responses to nociceptive signals, there is a continuous component to regulation, and that it may vary with differences in pain sensitivity. We hypothesize that this continuous regulation component occurs routinely in fMRI studies before noxious stimulation, as well as during, and after stimulation. This hypothesis was tested by analyzing data from 59 healthy participants in 4 previous fMRI studies in...
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Sensory sensitivity and symptom severity represent unique dimensions of chronic pain: a MAPP Research Network study
Chronic overlapping pain conditions (COPCs) are characterized by aberrant central nervous system processing of pain. This “centralized pain” phenotype has been described using a large and diverse set of symptom domains, including the spatial distribution of pain, pain intensity, fatigue, mood imbalances, cognitive dysfunction, altered somatic sensations, and hypersensitivity to external stimuli. Here, we used 3 cohorts, including patients with urologic chronic pelvic pain syndrome, a mixed pain cohort with other COPCs, and healthy individuals (total n = 1039) from the Multidisciplinary Approach to the Study of ...
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Psychophysical and vasomotor evidence for interdependency of TRPA1 and TRPV1-evoked nociceptive responses in human skin: an experimental study
The TRPA1 and TRPV1 receptors are important pharmaceutical targets for antipruritic and analgesic therapy. Obtaining further knowledge on their roles and interrelationship in humans is therefore crucial. Preclinical results are contradictory concerning coexpression and functional interdependency of TRPV1 and TRPA1, but no human evidence exists. This human experimental study investigated whether functional responses from the subpopulation of TRPA1+ nociceptors could be evoked after defunctionalization of TRPV1+ nociceptors by cutaneous application of high-concentration capsaicin. Two quadratic areas on each forearm were ran...
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Trigeminal ganglion transcriptome analysis in 2 rat models of medication-overuse headache reveals coherent and widespread induction of pronociceptive gene expression patterns
We report that both drug treatments change trigeminal ganglion gene expression to a similar extend. Of note, qualitative transcriptomic analysis shows that eletriptan and indomethacin prompt nearly identical, increased expression of genes coding for proteins involved in migraine pathogenesis and central pain sensitization such as neuropeptides, their cognate receptors, prostanoid, and nitric oxide–synthesizing enzymes, as well as TRP channels. These genes, however, were not affected in thoracic dorsal root ganglia. Of note, lowering of orofacial nociceptive thresholds, as well as forepaw hyperalgesia occurred in both...
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Pressure-induced referred pain areas are more expansive in individuals with a recovered fracture
This study compared the extent of pain referral in individuals recovered from a musculoskeletal trauma and healthy controls. Twenty pain-free participants recovered from a shoulder fracture and 20 age-/sex-matched controls participated in 2 experimental sessions (day-0 and day-1) separated by 24 hours. On both days, pressure pain thresholds were measured bilaterally at infraspinatus, supraspinatus, trapezius, and gastrocnemius muscles. Referred pain towards the shoulder region was induced by a 60-second pressure stimulation (pressure pain threshold + 20%) at the infraspinatus muscle and recorded on an electronic body chart...
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Research Paper Source Type: research

Should thoracic paravertebral blocks be used to prevent chronic postsurgical pain after breast cancer surgery? A systematic analysis of evidence in light of IMMPACT recommendations
The role of thoracic paravertebral block (PVB) in preventing chronic postsurgical pain (CPSP) after breast cancer surgery (BCS) has gained interest, but existing evidence is conflicting, and its methodological quality is unclear. This meta-analysis evaluates efficacy of PVB, compared with Control group, in preventing CPSP after BCS, in light of the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) recommendations. Electronic databases were searched for randomized trials comparing PVB with Control group for CPSP prevention after BCS. Eligible trials were assessed for adherence to IMMPACT r...
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Systematic Reviews and Meta-Analyses Source Type: research

Cannabis and cannabinoids for the treatment of people with chronic noncancer pain conditions: a systematic review and meta-analysis of controlled and observational studies
This review examines evidence for the effectiveness of cannabinoids in chronic noncancer pain (CNCP) and addresses gaps in the literature by: considering differences in outcomes based on cannabinoid type and specific CNCP condition; including all study designs; and following IMMPACT guidelines. MEDLINE, Embase, PsycINFO, CENTRAL, and clinicaltrials.gov were searched in July 2017. Analyses were conducted using Revman 5.3 and Stata 15.0. A total of 91 publications containing 104 studies were eligible (n = 9958 participants), including 47 randomised controlled trials (RCTs) and 57 observational studies. Forty-eight studies ex...
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Systematic Reviews and Meta-Analyses Source Type: research

Does the word “placebo” evoke a placebo response?
No abstract available (Source: Pain)
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Topical Review Source Type: research

Chronic pain in survivors of childhood cancer: a developmental model of pain across the cancer trajectory
No abstract available (Source: Pain)
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Topical Review Source Type: research

Targeting toll-like receptor-4 (TLR4)—an emerging therapeutic target for persistent pain states
Toll-like receptors (TLRs) are a family of pattern recognition receptors that initiate signaling in innate and adaptive immune pathways. The highly conserved family of transmembrane proteins comprises an extracellular domain that recognizes exogenous and endogenous danger molecules and an ectodomain that activates downstream pathways in response. Recent studies suggest that continuous activation or dysregulation of TLR signaling may contribute to chronic disease states. The receptor is located not only on inflammatory cells (meningeal and peripheral macrophages) but on neuraxial glia (microglia and astrocytes), Schwann cel...
Source: Pain - October 1, 2018 Category: Anesthesiology Tags: Comprehensive Review Source Type: research