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Pain-related cues are evolutionarily primed to capture attention, although evidence of attentional biases towards pain-related information is mixed in healthy individuals. The present study explores whether healthy individuals show significantly different eye-movement behaviours when viewing real-world pain-related scenes compared to neutral scenes. The effect of manipulating via written information the threat value of the pain-related scenes on eye-movement behaviours was also assessed.
Learn More >Vulvodynia is a remarkably prevalent chronic pain condition of unknown etiology. An increase in numbers of vulvar mast cells often accompanies a clinical diagnosis of vulvodynia and a history of allergies amplifies the risk of developing this condition. We previously showed that repeated exposures to oxazolone dissolved in ethanol on the labiar skin of mice led to persistent genital sensitivity to pressure and a sustained increase in labiar mast cells. Here we sensitized female mice to the hapten dinitrofluorobenzene (DNFB) dissolved in saline on their flanks, and subsequently challenged them with the same hapten or saline vehicle alone for ten consecutive days either on labiar skin or in the vaginal canal. We evaluated tactile ano-genital sensitivity, and tissue inflammation at serial timepoints. DNFB-challenged mice developed significant, persistent tactile sensitivity. Allergic sites showed mast cell accumulation, infiltration of resident memory CD8CD103 T cells, early, localized increases in eosinophils and neutrophils, and sustained elevation of serum Immunoglobulin E (IgE). Therapeutic intra-vaginal administration of Δ-tetrahydrocannabinol (THC) reduced mast cell accumulation and tactile sensitivity. Mast cell-targeted therapeutic strategies may therefore provide new ways to manage and treat vulvar pain potentially instigated by repeated allergenic exposures.
Learn More >Quantitative sensory testing (QST) is a formal variant of a time-honoured clinical examination technique in neurology, the sensory examination. Prototypical QST profiles have been found in human surrogate models of peripheral sensitization, central sensitization, and deafferentation. Probabilistic sorting of individual patients to any combination of these profiles has been developed, and there is emerging evidence for the predictive value of such sensory profiles for treatment efficacy. This way, QST aids in diagnostics of individual patients and may help guide their care in the future. Deficits in "dynamic" QST have been proposed as predictors of chronic pain (impaired descending inhibition and delayed recovery from central sensitization). Several psychological factors had previously been found to be predictors of pain chronicity (catastrophizing, self-efficacy, and neuroticism). The relative importance of psychological vs sensory testing predictors has not been evaluated. It is likely that both will have differential roles in clinical practice.
Learn More >This paper overviews available literature addressing behavioral and psychological aspects of cluster headache. Behavioral correlates of sleep and drug use are explored, as are the psychological correlates pertaining to psychopathology and cognitive functioning. We conclude with a review of the few investigations addressing adjunctive behavioral treatments for cluster headache, and provide suggestions for possible ways to enhance effects of behavioral interventions for this painful and difficult to treat headache disorder.
Learn More >Conditioned Pain Modulation (CPM) and Manipulation Induced Analgesia (MIA) may activate similar neurophysiological mechanisms to mediate their analgesic effects. This study assessed the association between CPM and MIA responses in people with lateral epicondylalgia (LE).
Learn More >Medication overuse headache (MOH) is the most prevalent chronic headache disorder with a prevalence between 1-2% worldwide. The disease has been acknowledged for almost 30 years, yet experts still disagree on how best to treat MOH. By performing a search in PubMed on the terms "medication overuse headache", "analgesics abuse headache", "rebound headache", "drug induced headache", and "headache AND drug misuse" limited to human studies published in English between January 1 2004 and November 1 2017, we aimed to evaluate current literature concerning predictors of treatment outcome, inpatient and outpatient treatment programs, initial versus latent administration of prophylactic medications, and to review the effect of prophylactic medications. Selection criteria were prospective, comparative or controlled trials on treatment of MOH in persons of at least 18 years of age. Several studies evaluated risk factors to predict the outcome of MOH treatment, but many studies were underpowered. Psychiatric comorbidity, high dependence score and overuse of barbiturates, benzodiazepines and opioids predicted a poorer outcome of withdrawal therapy. Patients with these risk factors benefit from inpatient treatment, whereas patients without risk factors benefit equally from in and outpatient treatment. Some medications for migraine prophylactics have shown better effect on MOH compared with placebo, but not when combined with withdrawal. We conclude that detoxification programs are of great importance in MOH treatment. Latent administration of prophylactic medications reduces the number of patients needing prophylactic medication. Individualizing treatment according to the predictors of outcome may improve treatment outcome and thus reduce work-related and treatment-related costs. This article is protected by copyright. All rights reserved.
Learn More >The monosynaptic stretch reflex (MSR) plays an important role in feedback control of movement and posture, but can also lead to unstable oscillations associated with tremor and clonus, especially when increased with spinal cord injury (SCI). To control the MSR and clonus after SCI we examined how serotonin regulates the MSR in the sacrocaudal spinal cord of rats with and without a chronic spinal transection. In chronic spinal rats, numerous 5-HT receptor agonists, including zolmitriptan, methylergonovine and 5-HT, inhibited the MSR with a potency highly correlated to their binding affinity to 5-HT1D receptors and not other 5-HT receptors. Selective 5-HT1D receptor antagonists blocked this agonist induced inhibition, though antagonists alone had no action, indicating a lack of endogenous or constitutive receptor activity. In normal uninjured rats, the MSR was likewise inhibited by 5-HT, but at much higher doses, indicating a supersensitivity after SCI. This supersensitivity resulted from the loss of the serotonin transporter SERT with spinal transection, since normal and injured rats were equally sensitive to 5-HT after blocking SERT, or to agonists not transported by SERT (zolmitriptan). Immunolabelling revealed that the 5-HT1D receptor was confined to superficial lamina of the dorsal horn, colocalized with CGRP positive C fibres, and eliminated by dorsal rhizotomy. 5-HT1D receptor labelling was not found on large proprioceptive afferents or alpha-motoneurons of the MSR. Thus, serotonergic inhibition of the MSR must act indirectly by modulating C fibre activity, opening up new possibilities for modulating reflex function and clonus via pain related pathways.
Learn More >We hypothesized that patients with characteristics of centralized pain (fibromyalgia (FM)-like phenotype) would be less likely to respond to radiofrequency ablation (RFA), which may explain some of the failures of this peripherally directed therapy.
Learn More >In this article, I review the concept of personalized pain management and consider how brain imaging and quantitative sensory testing can be used to derive biomarkers of chronic pain treatment outcome. I review how different modalities of brain imaging can be used to acquire information about brain structure and function and how this information can be linked to individual measures of pain.
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