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Fibromyalgia is a chronic pain syndrome characterized by central sensitization. A novel protocol based on slowly repeated evoked pain (SREP) appears to be a useful marker of pain sensitization in fibromyalgia patients. Whether SREP enhances diagnostic accuracy beyond key clinical symptoms that characterize fibromyalgia has not been examined.
Learn More >Past studies have shown that pain memories are often inaccurate, a phenomenon known as mnemonic pain bias. Pain memories are thought to play an important role on how future pain is felt. Recent evidence from our laboratory suggests that individuals who exaggerate past pain display increased superior temporal gyrus (STG) and parahippocampal gyrus (PHG) activity during the encoding of experimental painful stimulations, suggesting that these brain structures play an important role in pain memories.
Learn More >The United States is in the midst of an opioid overdose epidemic, with a significant portion of the burden associated with prescription opioids. In response, the CDC released a Guideline for Prescribing Opioids for Chronic Pain, which promotes access to treatment for opioid use disorder. Decades of research have linked childhood adversity to negative health and risk behavior outcomes, including substance misuse. Our present study builds upon this work to examine the relationship between adverse childhood experiences (ACEs) and prescription opioid misuse. We compiled data from the Behavioral Risk Factor Surveillance System implemented by Montana and Florida in 2010 and 2011, respectively. Logistic regressions (run in 2017) tested the associations between ACEs and subsequent prescription pain medicine/opioid misuse outcomes in adulthood. ACEs were prevalent, with 62.7% of respondents in Montana and 50% in Florida reporting at least one ACE. The presence of ACEs was positively associated with prescription opioid misuse across both samples. Respondents reporting three or more ACEs had increased odds of taking opioids more than prescribed, without a prescription, and for the feeling they cause. Our results support a strong link between ACEs and prescription opioid misuse. Opportunities to prevent opioid misuse start with assuring safe, stable, nurturing relationships and environments in childhood and across the lifespan to prevent ACEs from occurring, and intervening appropriately when they do occur. Substance use prevention programs for adolescents, appropriate pain management and opioid prescribing protocols, and treatments for opioid use disorder can address ACEs by enhancing treatment safety and effectiveness and can reduce the intergenerational continuity of early adversity.
Learn More >Complex regional pain syndrome (CRPS) is a debilitating chronic pain disorder typically in the upper or lower limbs. Whilst CRPS usually develops from a peripheral event, it is likely maintained by central nervous system changes. Indeed CRPS is reported to be associated with sensorimotor cortex changes, or functional 'reorganisation', as well as deficits such as poor tactile acuity. Whilst the mechanisms underpinning cortical reorganisation in CRPS are unknown, some have hypothesised that it involves disinhibition, i.e. a reduction in gamma-Aminobutyric acid (GABA) activity. In this study we addressed this hypothesis by using edited magnetic resonance spectroscopy (MRS) to determine sensorimotor GABA and glutamate concentrations in 16 humans with CRPS and 30 matched controls and the relationship of these concentrations with tactile acuity. We found that individuals with upper limb CRPS displayed reduced tactile acuity in the painful hand compared with the non-painful hand and pain-free controls. Despite this acuity deficit, CRPS was not associated with altered GABA or glutamate concentrations within the sensorimotor cortex on either the side that represents the affected or unaffected hand. Furthermore, there was no significant relationship between sensorimotor GABA or glutamate concentrations and tactile acuity in CRPS or control subjects. Although our sample was small, these data suggest that CRPS is not associated with altered total sensorimotor GABA or glutamate concentrations. Whilst these results are at odds with the sensorimotor cortex disinhibition hypothesis, it is possible that GABAergic mechanisms other than total GABA concentration may contribute to such disinhibition. Complex regional pain syndrome is a debilitating chronic pain disorder that usually affects the limbs. It is associated with altered sensorimotor cortex function including reorganisation and reduced tactile acuity, which are thought to result from reduced on-going inhibition. However, we found that this pain condition is not associated with reduced on-going sensorimotor inhibition in the form of gamma-Aminobutyric acid concentration, the major inhibitory neurotransmitter in the brain. These findings strongly suggest that changes in sensorimotor function in individuals with complex regional pain syndrome are explained by factors other than neurotransmitter concentration.
Learn More >Investigate the potential role of (mu-opioid receptor) and (catechol-O-methyltransferase enzyme) polymorphisms in postoperative acute, chronic and experimental thermal pain. A secondary analysis of 125 adult cardiac surgery patients that were randomized between fentanyl and remifentanil during surgery and genotyped. Patients in the fentanyl group with the high-pain sensitivity haplotype required less postoperative morphine compared with the average-pain sensitivity haplotype (19.4 [16.5; 23.0] vs 34.6 [26.2; 41.4]; p = 0.00768), but not to the low-pain sensitivity group (30.1 [19.1; 37.7]; p = 0.13). No association was found between haplotype and other pain outcomes or polymorphisms and the different pain modalities. haplotype appears to explain part of the variability in acute postoperative pain in adult cardiac surgery patients.
Learn More >Methadone is a long-acting opioid that has been reported to reduce postoperative pain scores and analgesic requirements and may attenuate development of chronic postsurgical pain. The aim of this secondary analysis of two previous trials was to follow up with patients who had received a single intraoperative dose of either methadone or traditional opioids for complex spine or cardiac surgical procedures.
Learn More >Pruritus is a major symptom of atopic dermatitis (AD) and is transmitted by a subpopulation of non-myelinated C-type free nerve endings in the epidermis and upper dermis. Stimulation of these nerve terminals is affected by histamine, neurotrophins and physical factors. Eosinophils of patients with AD are a source of neurotrophins, including brain-derived neurotrophic factor (BDNF), levels of which correlate with disease severity.
Learn More >The Canadian Guideline for Safe and Effective Use of Opioids for Chronic Non-Cancer Pain (COG) was developed in response to increasing rates of opioid-related hospital visits and deaths in Canada, and uncertain benefits of opioids for chronic non-cancer pain (CNCP). Following publication, we developed a list of evaluable outcomes to assess the impact of this guideline on practice and patient outcomes.
Learn More >Pain sensitization contributes to the complex osteoarthritis (OA) pain experience. The relation between hand OA imaging features and clinically assessed pain sensitization is largely unexplored. We aimed to examine the association of structural and inflammatory features of hand OA with local pressure pain thresholds in the Nor-Hand study.
Learn More >Crohn's disease is a chronic inflammatory disorder of the gastrointestinal tract associated with abdominal pain and diarrhea. Pain caused by Crohn's disease likely involves neurogenic inflammation which seems to involve the ion channel transient receptor potential ankyrin 1 (TRPA1). Since the promoter methylation of TRPA1 was shown to influence pain sensitivity, we asked if the expression of TRPA1 is dysregulated in patients suffering from Crohn's disease. The methylation rates of CpG dinucleotides in the TRPA1 promoter region were determined from DNA derived from whole blood samples of Crohn patients and healthy participants. Quantitative sensory testing was used to examine pain sensitivities.
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