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Chronic itch remains a highly prevalent disorder with limited treatment options. Most chronic itch diseases are thought to be driven by both the nervous and immune systems, but the fundamental molecular and cellular interactions that trigger the development of itch and the acute-to-chronic itch transition remain unknown. Here, we show that skin-infiltrating neutrophils are key initiators of itch in atopic dermatitis, the most prevalent chronic itch disorder. Neutrophil depletion significantly attenuated itch-evoked scratching in a mouse model of atopic dermatitis. Neutrophils were also required for several key hallmarks of chronic itch, including skin hyperinnervation, enhanced expression of itch signaling molecules, and upregulation of inflammatory cytokines, activity-induced genes, and markers of neuropathic itch. Finally, we demonstrate that neutrophils are required for induction of CXCL10, a ligand of the CXCR3 receptor that promotes itch via activation of sensory neurons, and we find that that CXCR3 antagonism attenuates chronic itch.
Learn More >Rapid conduction of nerve impulses is critical in life and relies on action potential (AP) leaps through the nodes of Ranvier (NRs) along myelinated nerves. While NRs are the only sites where APs can be regenerated during nerve conduction on myelinated nerves, ion channel mechanisms underlying the regeneration and conduction of APs at mammalian NRs remain incompletely understood. Here, we show that TREK-1 and TRAAK, the thermosensitive and mechanosensitive two-pore-domain potassium (K2P) channels, are clustered at NRs of rat trigeminal Aβ-afferent nerves with a density over 3,000-fold higher than that on their somas. These K2P channels, but not voltage-gated K channels as in other parts of nerves, are required for rapid AP repolarization at the NRs. Furthermore, these channels permit high-speed and high-frequency AP conduction along the myelinated afferent nerves, and loss of function of these channels at NRs retards nerve conduction and impairs sensory behavioral responses in animals.
Learn More >Fibromyalgia (FM) is a prevalent syndrome, characterised by chronic widespread pain, fatigue, and impaired sleep, that is challenging to diagnose and difficult to treat. The microbiomes of 77 women with FM and that of 79 control participants were compared using 16S rRNA gene amplification and whole-genome sequencing. When comparing FM patients with unrelated controls using differential abundance analysis, significant differences were revealed in several bacterial taxa. Variance in the composition of the microbiomes was explained by FM-related variables more than by any other innate or environmental variable and correlated with clinical indices of FM. In line with observed alteration in butyrate-metabolising species, targeted serum metabolite analysis verified differences in the serum levels of butyrate and propionate in FM patients. Using machine-learning algorithms, the microbiome composition alone allowed for the classification of patients and controls (receiver operating characteristic area under the curve 87.8%). To the best of our knowledge, this is the first demonstration of gut microbiome alteration in nonvisceral pain. This observation paves the way for further studies, elucidating the pathophysiology of FM, developing diagnostic aids and possibly allowing for new treatment modalities to be explored.
Learn More >Oxaliplatin is a cornerstone chemotherapeutic used in the treatment of colorectal cancer, the third leading cause of death in Western countries. Most side effects of this platinum-containing drug are adequately managed in the clinic, although acute and long-term neurotoxicity still severely compromises the quality of life of patients treated with oxaliplatin.We have previously demonstrated that therapeutically relevant concentrations/doses of oxaliplatin lead to a reduction in intracellular pH in mouse dorsal root ganglia neurons in vitro and in vivo and that this alteration sensitizes TRPA1 and TRPV1 channels, which most likely mediate the allodynia associated with treatment. In the present manuscript, we show that oxaliplatin leads to a reduction of intracellular pH by forming adducts with neuronal haemoglobin, which acts in this setting as a proton buffer. Furthermore, we show that FDA-approved drugs that inhibit carbonic anhydrase (an enzyme that is linked to haemoglobin in intracellular pH homeostasis), i.e. topiramate and acetazolamide, revert (i) oxaliplatin-induced cytosolic acidification and TRPA1 and TRPV1 modulation in dorsal root ganglia neurons in culture, (ii) oxaliplatin-induced cytosolic acidification of dorsal root ganglia of treated animals, and (iii) oxaliplatin-induced acute cold allodynia in mice while not affecting OHP-induced cytotoxicity on cancer cells.Our data would therefore suggest that reversal of oxaliplatin-induced cytosolic acidification is a viable strategy to minimize acute oxaliplatin-induced symptoms.
Learn More >The tendency to select threatening over benign interpretations of ambiguous bodily sensations and cues characterises young people with chronic pain. However, previous studies disagree over whether these biases extend to non-bodily harm situations such as social evaluation. Understanding the content of these biases is crucial to the development of pain management strategies seeking to modify such biases. Two hundred and forty-three young people aged 16-19 years completed an expanded version of the Adolescent Interpretation of Bodily Threat task. Using a factor-analytic approach, we removed items that did not consistently associate with bodily harm or social evaluation. Next, we examined whether the variance underlying negative and benign interpretations of bodily harm and social evaluation situations were best represented as a common factor (i.e., one-factor model), two distinct factors (i.e., two-factor model), or one common and two distinct factors (i.e., two-factor bi-factor model) in all adolescents. We then compared youth with and without persistent and impairing pain on factor scores derived from the best-fitting model. While negative interpretations of bodily harm and social evaluation situations emerged as distinct factors, benign interpretations across situations were best captured by a common factor and two situation-specific factors (i.e., bifactor model). Group comparisons showed that young people with moderate-to-high pain interference were more likely to endorse negative interpretations across all situations, and less likely to manifest a general benign interpretational style, than youth without interfering pain although some of these group differences were explained by co-occurring anxiety and depressive symptoms. Replication of these findings is needed.
Learn More >The nitric-oxide donor nitroglycerin (NTG) administration induces a facilitation of nociceptive pathways in episodic migraine. This study aims to test the hypothesis that induced spinal sensitization could be more pronounced in patients affected by high frequency migraine (HF-MIG) respect to low frequency migraine (LF-MIG).We enrolled 28 patients with LF-MIG (1-5 migraine days/month), 19 patients with HF-MIG (6-14 migraine days/month) and 21 healthy controls (HC). Spinal sensitization was evaluated with the neurophysiological recording of the temporal summation threshold (TST) of the nociceptive withdrawal reflex at the lower limb. TST was recorded at baseline and 30, 60 and 120 minutes after NTG administration (0.9 mg sublingual).Spinal sensitization was detected in LF-MIG at 60 (p=0.010) and 120 minutes (p=0.001) and in HF-MIG at 30 (p=0.008), 60 (p=0.001) and 120 minutes (p=0.001) after NTG administration. TST did not change in HC (p=0.899). Moreover, TST reduction was more pronounced in HF-MIG respect to LF-MIG (p=0.002).The percentage of patients who developed a migraine-like headache after NTG was comparable in the two migraine groups (LF-MIG: 53.6%, HF-MIG: 52.6%, p=0.284), while no subjects in HC group developed a delayed-specific headache. Notably, the latency of headache onset was significantly shorter in the HF-MIG group when compared to the LF-MIG group (p=0.015).Our data demonstrate a direct relationship between migraine frequency and both neurophysiological and clinical parameters, to suggest an increasing derangement of the nociceptive system control as the disease progresses, probably as a result of the interaction of genetic and environmental factors.
Learn More >Diabetic peripheral neuropathy (DPN) is a common complication of both type 1 and 2 diabetes. It is a leading cause of lower-limb amputation and disabling neuropathic pain. Amputations in patients with diabetes have a devastating effect on quality of life and are associated with an alarmingly low life expectancy (on average only 2 years from the amputation). Amputation also places a substantial financial burden on health-care systems and society in general. With the introduction of national diabetes eye screening programmes, the prevalence of blindness in working-age adults is falling. This is not the case, however, with diabetes related amputations. In this Review, we appraise innovative point-of-care devices that enable the early diagnosis of DPN and assess the evidence for early risk factor-based management strategies to reduce the incidence and slow the progression of DPN. We also propose a framework for screening and early multifactorial interventions as the best prospect for preventing or halting DPN and its devastating sequelae.
Learn More >Neurogenic inflammation, mediated by the activation of primary neurons, is thought to be an important factor in migraine pathophysiology. Programmed cell death ligand-1 (PD-L1) can suppress the immune response through the Programmed cell death-1 receptor. However, the role of PD-L1/PD-1 in migraine remains unclear. In this study we evaluated the expression and role of PD-L1/PD-1 in the trigeminal ganglia in an animal model of acute migraine.
Learn More >An estimated 2.5-3.1% of people with episodic migraine develop chronic migraine in a year. Several risk factors are associated with an increased risk for this transformation. We conducted a systematic review and meta-analysis to provide quantitative and qualitative data on predictors of this transformation.
Learn More >To evaluate differences in how mothers and fathers perceive and respond to their adolescents' chronic pain before and after The Comfort Ability Program (CAP), a 1-day cognitive-behavioral intervention, and to compare outcomes between mother-father dyads and mothers who attended the intervention alone.
Learn More >Despite the availability of measures for assessing physical, psychological, and health impact in children with chronic pain, there are not established guidelines for interpretation of children's pain outcomes following psychological treatment. The purpose of this topical review is to discuss clinical significance as a neglected area of consideration in pediatric chronic pain assessment and to make recommendations on how the field can move toward benchmarking on core outcome domains.
Learn More >Opioid overdose is the leading cause of injury-related death in the United States. Several studies have shown that surgeons overprescribe opioids, and guidelines for appropriate opioid prescribing are available. Concern about patient-reported satisfaction scores may be a barrier to surgeons adopting guideline-directed prescribing.
Learn More >Concerns about the adequacy of pain management among older adults are increasing, particularly with restrictions on opioid prescribing.
Learn More >Intranasal lidocaine has been shown to be effective in treating patients with acute migraines; however, its efficacy is still controversial. In this study, we intend to assess the efficacy and safety of intranasal lidocaine compared with a placebo or an active comparator for the treatment of migraines.
Learn More >A striking and debilitating property of the nervous system is that damage to this tissue can cause chronic intractable pain, which persists long after resolution of the initial insult. This neuropathic form of pain can arise from trauma to peripheral nerves, the spinal cord, or brain. It can also result from neuropathies associated with disease states such as diabetes, human immunodeficiency virus/AIDS, herpes, multiple sclerosis, cancer, and chemotherapy. Regardless of the origin, treatments for neuropathic pain remain inadequate. This continues to drive research into the underlying mechanisms. While the literature shows that dysfunction in numerous loci throughout the CNS can contribute to chronic pain, the spinal cord and in particular inhibitory signalling in this region have remained major research areas. This review focuses on local spinal inhibition provided by dorsal horn interneurons, and how such inhibition is disrupted during the development and maintenance of neuropathic pain.
Learn More >To investigate the temporal changes of circadian rhythmicity in relation to the disease course in patients with cluster headache.
Learn More >The Fc gamma receptor I (FcγRI; CD64) is the high-affinity receptor of the immunoglobulin G protein (IgG). It is usually expressed in immune cells and has recently been identified to distribute in the nervous system and play critical roles in various neurological disorders. Presently, the impacts of FcγRI in neuropathic pain was largely unknown. Here, we aimed to investigate the impacts of FcγRI in neuropathic pain through pain-related neurobehavioral studies and underlying mechanisms by biochemical methods in animal and cell models. Specifically, we first utilized the chronic constriction injury (CCI) rat model that displayed neuropathic pain related symptoms and signs, including thermal hyperalgesia and mechanical allodynia. These neurobehavioral defects were significantly attenuated by the anti-FcγRI antibody, which was associated with reduced levels of neuropeptide substance P, C, and TNF-α. Furthermore, we validated our animal findings using the embryonically neural crest-originated PC12 cell model. We found that stimulation of the IgG immune complex led to increased levels of FcγRI and inflammatory mediators, which were attenuated by the anti-FcγRI antibody in these cells. Collectively, our results from animal and cell-based studies suggest that FcγRI is a critical player for peripheral nerve injury-induced neuropathic pain by mediating pain-related immunological events, which therefore may provide a new therapeutic target for protection against chronic pain.
Learn More >Diabetes mellitus is becoming increasingly common worldwide. As this occurs, there will be an increase in the prevalence of known comorbidities from this disorder of glucose metabolism. One of the most disabling adverse comorbidities is diabetic neuropathy. The most common neuropathic manifestation is distal symmetric polyneuropathy, which can lead to sensory disturbances, including diminished protective sense, making patients prone to foot injuries. However, focal, multifocal, and autonomic neuropathies are also common. Diabetic nerve pain and Charcot osteoarthropathy are advanced neuropathic conditions that portend a severe deterioration in quality of life. To combat these symptoms, along with glycemic control and establishment of health care systems to educate and support patients with the complexities of diabetes, there are pharmacologic remedies to ameliorate the neurologic symptoms. Several guidelines and review boards generally recommend the use of tricyclic antidepressants, serotonin/norepinephrine-reuptake inhibitors, α-2-delta ligands, and anticonvulsants as medications to improve painful diabetic neuropathy and quality of life.
Learn More >Animal models reveal that deafferenting forelimb injuries precipitate reorganization in both contralateral and ipsilateral somatosensory cortices. The functional significance and duration of these effects are unknown, and it is unclear whether they also occur in injured humans. We delivered cutaneous stimulation during functional magnetic resonance imaging (fMRI) to map the sensory cortical representation of the intact hand and lower face in a group of chronic, unilateral, upper extremity amputees (N = 19) and healthy matched controls (N = 29). Amputees exhibited greater activity than controls within the deafferented former sensory hand territory (S1f) during stimulation of the intact hand, but not of the lower face. Despite this cortical reorganization, amputees did not differ from controls in tactile acuity on their intact hands. S1f responses during hand stimulation were unrelated to tactile acuity, pain, prosthesis usage, or time since amputation. These effects appeared specific to the deafferented somatosensory modality, as fMRI visual mapping paradigm failed to detect any differences between groups. We conclude that S1f becomes responsive to cutaneous stimulation of the intact hand of amputees, and that this modality-specific reorganizational change persists for many years, if not indefinitely. The functional relevance of these changes, if any, remains unknown.
Learn More >Post-traumatic headache (PTH) is associated with considerable disability and reduced health-related quality of life. Despite the very high prevalence of PTH, there are no evidence-based guidelines for PTH treatment. Thus, we found it timely to provide a systematic review of the current literature on acute and preventive pharmacological treatment of PTH using PubMed and Embase databases.
Learn More >The goal of this narrative review was to give an up-to-date overview of the peripheral and central neurostimulation methods that can be used to treat chronic pain. Special focus has been given to three pain conditions: neuropathic pain, nociplastic pain and primary headaches. Both non-invasive and invasive techniques are briefly presented together with their pain relief potentials. For non-invasive stimulation techniques, data concerning transcutaneous electrical nerve stimulation (TENS), transcranial direct current stimulation (tDCS), repetitive transcranial magnetic stimulation (rTMS), remote electrical neuromodulation (REN) and vagus nerve stimulation (VNS) are provided. Concerning invasive stimulation techniques, occipital nerve stimulation (ONS), vagus nerve stimulation (VNS), epidural motor cortex stimulation (EMCS), spinal cord stimulation (SCS) and deep brain stimulation (DBS) are presented. The action mode of all these techniques is only partly understood but can be very different from one technique to the other. Patients' selection is still a challenge. Recent consensus-based guidelines for clinical practice are presented when available. The development of closed-loop devices could be of interest in the future, although the clinical benefit over open loop is not proven yet.
Learn More >Serotonin norepinephrine reuptake inhibitors (SNRIs) are commonly co-prescribed with opioids for chronic pain. The purpose of this study was to describe pain and mood response to venlafaxine among older adults with chronic low back pain (CLBP) and depression relative to opioid exposure.
Learn More >Persistent idiopathic facial pain (PIFP) is a subtype of painful cranial neuropathies and other facial pains. The involvement of neuropathic mechanisms in PIFP, however, remains controversial. Using the Douleur Neuropathique 4 (DN4) questionnaire, the present study examined neuropathic characteristics in patients with PIFP.
Learn More >Fatty-acid amide hydrolase (FAAH) is an intracellular serine hydrolase that catalyzes the cleavage of endogenous fatty-acid amides, including the endocannabinoid anandamide (AEA). We previously reported that the peripherally restricted FAAH inhibitor URB937, which selectively increases AEA levels outside the central nervous system, reduces hyperalgesia and c-Fos expression in the trigeminal nucleus caudalis (TNC) and the locus coeruleus in an animal model of migraine based on nitroglycerin (NTG) administration.
Learn More >The thalamus is a key region for the transmission of nociceptive information in the central modulation of pain and has been studied in the setting of numerous chronic pain conditions. Brain-derived neurotrophic factor (BDNF) is considered an important modulator for mediating nociceptive pathways in chronic pain. The present study aimed to investigate whether there was thalamus-related abnormal functional connectivity or relevant serum BDNF level alterations during periovulation in long-term primary dysmenorrhea (PDM). Thalamic subregions were defined according to the Human Brainnetome Atlas. Functional connectivity analyses were performed in 36 patients in the periovulatory phase and 29 age-, education-, and gender-matched healthy controls. Serum BDNF levels were evaluated by enzyme-linked immunosorbent assay and a significantly higher BDNF level was detected in PDM patients. Compared with HCs, PDM patients had abnormal functional connectivity of thalamic-subregions, mainly involving with prefrontal cortex, sensorimotor cortex, and temporal cortex. In addition, the functional connectivity of thalamic-subregions showed significant interactive effect correlated with serum BDNF level between PDM and HCs. It has been suggested that there were maladaptive or adoptive alteration associated with chronic menstrual pain even without the ongoing menstrual pain. BDNF might play a role in the development and chronicity of central nervous system dysfunction. These findings provided more accurate information about the involvement of the thalamus in the pathophysiology of PDM.
Learn More >Current patient-reported outcome measures for itch are limited and may not capture its full impact on health-related quality of life (HRQOL). We sought to develop, calibrate and validate banks of questions assessing the HRQOL impact of itch as part of Patient-Reported Outcomes Measurement Information System® (PROMIS®). A systematic process of literature review, content-expert review, qualitative research, testing in a sample of 600 adults, classical test theory methods, and item response theory (IRT) analyses were applied. Exploratory and confirmatory factor analyses were followed by item response theory (IRT) model and item fit analyses. Four itch-related item banks were developed: (1) general concerns, (2) mood and sleep, (3) clothing and physical activity, and (4) scratching behavior. IRT and expert content review narrowed the item banks to 25, 18, 15 and 5 items, respectively. Validity of the item banks was supported by good convergent and discriminant validity with itch intensity, internal consistency and no significant floor or ceiling effects. In conclusion, the PROMIS Itch Questionnaire (PIQ) banks have excellent measurement properties and efficiently and comprehensively assess the burden of itch.
Learn More >Chronic pain is a major health problem, affecting 10-30% of the population in developed countries. While chronic pain is defined as "a persistent complaint of pain lasting for more than the usual period for recovery," recently accumulated lines of evidence based on human brain imaging have revealed that chronic pain is not simply a sustained state of nociception, but rather an allostatic state established through gradually progressing plastic changes in the central nervous system. To visualize the brain activity associated with spontaneously occurring pain during the shift from acute to chronic pain under anesthetic-free conditions, we used manganese-enhanced magnetic resonance imaging (MEMRI) with a 9.4-T scanner to visualize neural activity-dependent accumulation of manganese in the brains of mice with hind paw inflammation. Time-differential analysis between 2- and 6-h after formalin injection to the left hind paw revealed a significantly increased MEMRI signal in various brain areas, including the right insular cortex, right nucleus accumbens, right globus pallidus, bilateral caudate putamen, right primary/secondary somatosensory cortex, bilateral thalamus, right amygdala, bilateral substantial nigra, and left ventral tegmental area. To analyze the role of the right amygdala in these post-formalin MEMRI signals, we repeatedly inhibited right amygdala neurons during this 2-6-h period using the "designer receptors exclusively activated by designer drugs" (DREADD) technique. Pharmacological activation of inhibitory DREADDs expressed in the right amygdala significantly attenuated MEMRI signals in the bilateral infralimbic cortex, bilateral nucleus accumbens, bilateral caudate putamen, right globus pallidus, bilateral ventral tegmental area, and bilateral substantia nigra, suggesting that the inflammatory pain-associated activation of these structures depends on the activity of the right amygdala and DREADD-expressing adjacent structures. In summary, the combined use of DREADD and MEMRI is a promising approach for revealing regions associated with spontaneous pain-associated brain activities and their causal relationships.
Learn More >Presynaptic Ca2.2 channels control calcium entry that triggers neurotransmitter release at both central and peripheral synapses. The Cacna1b gene encodes the α1-pore forming subunit of Ca2.2 channels. Distinct subsets of splice variants of Ca2.2 derived from cell-specific alternative splicing of the Cacna1b pre-mRNA are expressed in specific subpopulations of neurons. Four cell-specific sites of alternative splicing in Cacna1b that alter Ca2.2 channel function have been described in detail: three cassette exons (e18a, e24a, and e31a) and a pair of mutually exclusive exons (e37a/e37b). Cacna1b mRNAs containing e37a are highly enriched in a subpopulation of nociceptors where they influence nociception and morphine analgesia. E37a-Cacna1b mRNAs are also expressed in brain, but their cell-specific expression in this part of the nervous system, their functional consequences in central synapses and their role on complex behavior have not been studied. In this report, we show that e37a-Cacna1b mRNAs are expressed in excitatory projection neurons where Ca2.2 channels are known to influence transmitter release at excitatory inputs from entorhinal cortex (EC) to dentate gyrus (DG). By comparing behaviors of WT mice to those that only express e37b-Ca2.2 channels, we found evidence that e37a-Ca2.2 enhances behavioral responses to aversive stimuli. Our results suggest that alternative splicing of Cacna1b e37a influences excitatory transmitter release and couples to complex behaviors.
Learn More >There is often dissociation between inflammatory activity and abdominal pain in children with inflammatory bowel disease (IBD), suggesting other factors may play a role in the pain experience.
Learn More >Opioids are commonly used to provide analgesia for cancer pain, and functional opioid receptors have been identified on natural killer (NK) cells, the lymphocytes responsible for surveillance and elimination of cancer cells. Opioids also bind to other lymphocyte receptors, such as Toll-like receptor (TLR)-4. Here, we characterized the effects of morphine on primary human NK cell cytotoxicity and mediator release, which occur through classical opioid receptor or TLR4 signaling.
Learn More >Stasis dermatitis (SD) is a common disease in the elderly population, with pruritus being one of the bothersome symptoms. However, there are few therapeutic modalities available for SD-associated itch because little is known about its pathophysiological mechanism. Therefore, we sought to investigate the mediators of itch in SD using an immunofluorescence study on patient lesions focusing on IL-31. Ex vivo stimulation studies using murine peritoneal macrophages were also used to elucidate the pathological mechanisms of IL-31 generation. In SD lesions, dermal infiltrating IL-31(+) cells were increased in number compared to healthy controls, and the majority of IL-31(+) cells were CD68(+) macrophages. The presence of itch in SD was significantly associated with the amount of CD68(+)/IL-31(+) macrophages and CD68(+)/CD163(+) M2 macrophages. The number of CD68(+)/IL-31(+) macrophages was correlated with the number of dermal CCR4(+) Th2 cells, IL-17(+) cells, basophils, substance P(+) cells, and dermal deposition of periostin and hemosiderin. Furthermore, murine peritoneal macrophages expressed an M2 marker arginase-1 and generated IL-31 when stimulated with a combination of substance P, periostin, and red blood cell lysate (representing hemosiderin). IL-31 from macrophages may play a role in itch in SD.
Learn More >To determine preliminary outcomes of a treatment for refractory pediatric migraine that integrates outpatient dihydroergotamine (DHE) infusion with interdisciplinary adjunctive care.
Learn More >This study sought to determine if pre- to post-treatment changes in pain-related activity patterns (i.e., overdoing, avoidance, and pacing) were associated with pre- to post-treatment changes in function (i.e., pain interference, psychological function, and physical function) in patients with fibromyalgia syndrome who participated in either an operant learning- or an energy conservation-based training in activity management.
Learn More >Neurobiological mechanisms can be involved in early programming of pain sensitization. We aimed to investigate the association between early-life pain experience and pre-adolescence spinal pain. We conducted a study of 29,861 pre-adolescents (age 11-14) from the Danish National Birth Cohort. As indicators of early-life pain, we used infantile colic and recurrent otitis media, reported by mothers when their children were 6 and 18 months. Self-reported spinal pain (neck, middle back, and/or low back pain) was obtained in the 11-year follow-up, classified according to severity. Associations between early-life pain and spinal pain in pre-adolescents were estimated using multinomial logistic regression models. To account for sample selection, inverse probability weighting was applied. Children experiencing pain in early life were more likely to report severe spinal pain in pre-adolescence. The association appeared stronger with exposure to two pain exposures (relative risk ratio, 1.31; 95% CI, 1.02-1.68) rather than one (relative risk ratio, 1.14; 95% CI, 1.05-1.24). We observed similar results when using headache and abdominal pain as outcome measures, underpinning a potential neurobiological or psychosocial link in programming of pain sensitization.Conclusion: Experience of early-life pain is seemingly associated with spinal pain in pre-adolescence. The study highlights that early-life painful experiences can influence programming future pain responses. What is Known: • Spinal pain in pre-adolescents is common, causes marked discomfort and impairment in everyday life, and may be an important predictor of spinal pain later in life. • Neurobiological mechanisms have been suggested as involved in early programming of pain sensitization. What is New: • Pain exposure in early postnatal life in terms of infantile colic and recurrent otitis media is associated with spinal pain in pre-adolescence; thus, experience of such painful conditions in the early postnatal period may seemingly influence programming of future pain sensation.
Learn More >Patients with chronic pelvic pain (CPP) may have pain refractory to conventional pain management strategies. Neuromodulation could provide relief of pain.
Learn More >To investigate a proposed cognitively-mediated pathway whereby pain contributes to gait impairments by acting as a distractor in community-living older adults.
Learn More >To evaluate the effect of a prospective opioid reduction intervention after radical prostatectomy (based on a surgery-specific guideline and education) on post-discharge opioid prescribing, use, disposal, and need for additional opioid mediation.
Learn More >The study aims were 1) to investigate the direction of mutual inhibitory pathways on itch intensity by utilizing conditioned pain modulation paradigms for pain and itch attenuation and 2) to explore whether itch severity is affected by the individual pain sensitivity profile, as well as pain scores reported during the tests and the past week.
Learn More >Prostate cancer and prostatitis are both significant health concerns. A large number of studies have established that the occurrence of the two is closely related. However, the most common prostatitis, type III chronic prostatitis/chronic pelvic pain syndromes (CP/CPPS), is reported to not correlate with the occurrence of prostate cancer. Although the etiology of CP/CPPS is unknown, it may be related to the autoimmune mechanism favored by most studies. Manipulating the immune system and targeting tumor microenvironment are promising new methods for the treatment of prostate cancer. Therefore, this review focuses on the immune cells and cytokines of CP/CPPS and prostate cancer from the perspective of biological immunology and immune microenvironment. We discuss T-regulatory (Treg) and T helper 17 (Th17) cells dysfunction, the abnormal regulation of T helper 1(Th1) and T helper 2 (Th2) cells, macrophages and their related cytokines as key activators in CP/CPPS. In addition, we discuss the roles of Treg and Th17 cells, Th1 and Th2 cells, and related cytokines in modulating prostate cancer progression. This review highlights the concept that immune cells and cytokines provide a research strategy for the etiology of CP/CPPS and offer potentially promising targets for the treatment of prostate cancer.
Learn More >To evaluate previous results from a questionnaire-based study, we studied objective neuropathy measures to determine sex differences in the prevalence of neuropathy and neuropathic pain in longstanding type 1 diabetes. Despite better neuropathy measures in females compared to males, we confirmed a trend towards higher neuropathic pain in females.
Learn More >Tibial fracture is associated with inflammatory reaction leading to severe pain syndrome. Bradykinin receptor activation is involved in inflammatory reactions, but has never been investigated in fracture pain.
Learn More >The STarT Back Screening Tool (SBT) identifies patients with low back pain (LBP) at risk of a worse prognosis of persistent disabling back pain, and thereby facilitates triage to appropriate treatment level. However, the SBT does not consider the pain distribution, which is a known predictor of chronic widespread pain (CWP). The aim of this study was to determine if screening by the SBT and screening of multisite chronic widespread pain (MS-CWP) could identity individuals with a worse prognosis. A secondary aim was to analyze self-reported health in individuals with and without LBP, in relation to the combination of these two screening tools.
Learn More >Trunk muscle dysfunction is often regarded as a key feature of non-specific chronic low back pain (NSCLBP) despite being poorly understood and variable with increases, decreases and no change in muscle activity reported. Differences in thoraco-lumbar kinematics have been observed in motor control impairment NSCLBP subgroups (Flexion Pattern, Active Extension Pattern) during static postures and dynamic activities. However, potential differences in muscle activity during functional tasks has not been established in these subgroups to date.
Learn More >The pathogenesis of medication overuse headache (MOH) involves hyperexcitability of cortical and trigeminal neurons. Derangement of the brainstem modulating system, especially raphe nuclei may contribute to this hyperexcitability. The present study aimed to investigate the involvement of the nucleus raphe magnus (NRM) in the development of cortical and trigeminal hyperexcitability in a rat model of MOH.
Learn More >Persistent opioid use following total joint replacement (TJR) surgery is common; however, the association between pre-surgical opioid use and surgery type has not been established. The objective of this study was to determine the association between pre-surgery opioid use and persistent post-surgery opioid use in TJR patients compared to other elective surgical patients.
Learn More >Allodynia in Menstrually Related Migraine: Score Assessment by Allodynia Symptom Checklist (ASC-12).
The aim of this study was to compare the allodynia score in headache attacks related and not related to menstruation in women diagnosed with menstrually related migraine without aura.
Learn More >Cochrane is an international non-profit organization established in 1993 to produce and disseminate high quality and unbiased systematic reviews of evidence on health care interventions. At the forefront of systematic review methodology, Cochrane is generally accepted to be among the most carefully prepared and rigorous sources of systematic review evidence. There are numerous Cochrane reviews on nonpharmacologic interventions for pain and multiple Cochrane reviews evaluating acupuncture therapy in pain conditions. But how complete and up to date are those reviews relative to other rigorous systematic reviews with meta-analyses of acupuncture therapy for pain published in the literature? In this 'snapshot' overview, we found 22 relevant Cochrane reviews, some concluding that acupuncture therapy is probably useful for treating specific pain conditions. However, many of the conditions for which acupuncture is most commonly used are either not represented in Cochrane reviews or the existing Cochrane reviews are seriously outdated and do not reflect current evidence. This creates confusion with the risks of adverse effects and addiction liability associated with pain medications, the prevalence of chronic pain, the ongoing opioid epidemic and the need for evidence-based options for pain as part of comprehensive pain care. Clinicians and patients want clarification on safe and effective options to treat pain. Issues involving reviewed trials' inadequate use of sham comparators, of acupuncture as a complex intervention with interactive components and a shift in research focus from efficacy trials to real-world pragmatic trials are discussed in relation to updating Cochrane reviews of acupuncture therapy for pain.
Learn More >The pathophysiological mechanisms of migraine transformation are debated. Modifications of plasma oxidative stress biomarkers have been described in chronic migraine. OnabotulintoxinA (BoNT/A) treatment, approved for chronic migraine prophylaxis, possibly reduces pain neurotransmitters release and oxidative stress products. Aims of our study were to investigate differences in the levels of selected plasmatic oxidative stress biomarkers (Advanced Oxidation Protein Products (AOPP), Ferric Reducing Antioxidant Power (FRAP), Thiolic Groups (SH)) comparing chronic migraineurs (CM) and healthy controls (HC). We also explored possible clinical and biochemical modifications in the CM group after six months of treatment with BoNT/A. At the baseline, we found higher values of AOPP ( < 0.001), and lower values of SH ( < 0.001) and FRAP ( = 0.005) in the CM group. At the six-month follow-up we found a reduction of AOPP ( < 0.001) and an increase of FRAP ( < 0.001) and SH ( = 0.023) within the CM group. BoNT/A treatment improved migraine symptoms in the CM group. We confirmed previous reports of imbalanced antioxidant mechanisms in chronic migraine showing lower antioxidant capacities in patients than controls. BoNT/A improved the levels of plasma oxidative stress biomarkers and confirmed its role as an effective prophylactic treatment for CM. Other studies should investigate the potential antioxidant properties of BoNT/A treatment.
Learn More >One-size-fits-all interventions reduce chronic low back pain (CLBP) a small amount. An individualised intervention called cognitive functional therapy (CFT) was superior for CLBP compared with manual therapy and exercise in one randomised controlled trial (RCT). However, systematic reviews show group interventions are as effective as one-to-one interventions for musculoskeletal pain. This RCT investigated whether a physiotherapist-delivered individualised intervention (CFT) was more effective than physiotherapist-delivered group-based exercise and education for individuals with CLBP.
Learn More >Brain structure and function were reported to be altered in migraine. Importantly our earlier results showed that white matter diffusion abnormalities and resting state functional activity were affected differently in the two subtypes of the disease, migraine with and without aura. Resting fluctuation of the BOLD signal in the white matter was reported recently. The question arising whether the white matter activity, that is strongly coupled with gray matter activity is also perturbed differentially in the two subtypes of the disease and if so, is it related to the microstructural alterations of the white matter. Resting state fMRI, 60 directional DTI images and high-resolution T1 images were obtained from 51 migraine patients and 32 healthy volunteers. The images were pre-processed and the white matter was extracted. Independent component analysis was performed to obtain white matter functional networks. The differential expression of the white matter functional networks in the two subtypes of the disease was investigated with dual-regression approach. The Fourier spectrum of the resting fMRI fluctuations were compared between groups. Voxel-wise correlation was calculated between the resting state functional activity fluctuations and white matter microstructural measures. Three white matter networks were identified that were expressed differently in migraine with and without aura. Migraineurs with aura showed increased functional connectivity and amplitude of BOLD fluctuation. Fractional anisotropy and radial diffusivity showed strong correlation with the expression of the frontal white matter network in patients with aura. Our study is the first to describe changes in white matter resting state functional activity in migraine with aura, showing correlation with the underlying microstructure. Functional and structural differences between disease subtypes suggest at least partially different pathomechanism, which may necessitate handling of these subtypes as separate entities in further studies.
Learn More >Atopic dermatitis (AD) is a highly pruritic chronic inflammatory skin disorder. Ruxolitinib, a selective inhibitor of Janus kinase (JAK)-1 and JAK2, potently suppresses cytokine signaling involved in AD pathogenesis.
Learn More >Complex regional pain syndrome (CRPS) is related to microcirculation impairment caused by tissue hypoxia and peripheral cytokine overproduction in the affected human limb and chronic post-ischemic pain (CPIP) is considered as an animal model for this intractable disease. Previous studies suggest that the pathogenesis of CPIP involves the hypoxia inducible factor-1α (HIF-1α) and an exaggerated regional inflammatory and free radical response. The inhibition of HIF-1α is known to relieve CPIP. So, propofol, as a free radical scavenger, is very likely to be beneficial in terms of relieving CPIP.
Learn More >Fibromyalgia (FM) is a prevalent and highly disabling chronic pain syndrome. However, differences among patients regarding how pain impacts on daily life are remarkable. The main aim of this study was to identify clinical and pain-related cognitive variables characterizing patients reporting high adaptability despite experiencing severe chronic pain.
Learn More >Meniere's disease (MD) is a chronic condition affecting the inner ear whose precise etiology is currently unknown. We propose the hypothesis that MD is a migraine-related phenomenon which may have implications for future treatment options for both diseases. The association between MD and migraine is both an epidemiological and a mechanistic one, with up to 51% of individuals with MD experiencing migraine compared to 12% in the general population. The presence of endolymphatic hydrops in those with MD may be the factor that unites the two conditions, as hydropic inner ears have an impaired ability to maintain homeostasis. Migraine headaches are theorized to cause aura and symptoms via spreading cortical depression that ultimately results in substance P release, alterations in blood flow, and neurogenic inflammation. Chronically hydropic inner ears are less able to auto-regulate against the changes induced by active migraine attacks and may ultimately manifest as MD. This same vulnerability to derangements in homeostasis may also explain the common triggering factors of both MD attacks and migraine headaches, including stress, weather, and diet. Similarly, it may explain the efficacy of common treatments for both diseases: current migraine treatments such as anti-hypertensives and anti-convulsants have shown promise in managing MD. Though the etiology of both MD and migraine is likely multifactorial, further exploration of the association between the two conditions may illuminate how to best manage them in the future. MD is likely a manifestation of cochleovestibular migraine, which occurs as a result of migraine related changes in both the cochlea and vestibule.
Learn More >Clinical studies have shown that schizophrenia is accompanied by hypoalgesia. Accordingly, we have previously reported that a chronic schizophrenia-related rat substrain (Wisket) showed decreased acute heat pain sensitivity. The aim of the present study was to determine the mechanical pain sensitivity and the effects of opioid ligands in a chronic osteoarthritic pain model generated using Wisket rats. Our previous molecular biological studies indicated that the impairment in opioid and cannabinoid receptor functions observed in these animals did not explain their altered pain sensitivity. Therefore, we aimed to investigate another endogenous antinociceptive system, i.e., the oxytocinergic system (which is also implicated in schizophrenia) via the determination the brain-region specific oxytocin receptor mRNA expression in Wisket rats. Osteoarthritis was induced in male adult control Wistar rats without any interventions and in Wisket rats after juvenile social isolation and ketamine treatment. The degree of allodynia and the effects of systemic morphine or intrathecal endomorphin-1 administration were determined. Furthermore, the expression of the oxytocin receptor mRNA was assessed in different brain structures (prefrontal cortex, striatum, diencephalon, brainstem, and olfactory bulb). A lower degree of allodynia was observed in the Wisket group compared with control animals 1 and 2 weeks after the induction of osteoarthritis, which was accompanied by a comparable degree of edema. Systemically or intrathecally applied opioids caused similar time-response curves in both groups, with apparently shorter effects in Wisket animals. The expression of the oxytocin receptor mRNA was lower in most of the brain regions (with the exception of the diencephalon) investigated in Wisket rats vs. the control animals. In summary, both acute and chronic hypoalgesia (as nonspecific symptoms in patients with schizophrenia) can be simulated in Wisket animals as endophenotypes despite the impairment of the endogenous antinociceptive systems evaluated. Thus, this model might be an appropriate tool for further investigation of the molecular basis of altered pain perception in schizophrenia.
Learn More >Medication Overuse Headache (MOH) is a prevalent and disabling disorder resulting from the overuse of analgesic drugs, triptans or other acute headache medications. In previous proteomic studies, several proteins have been found at high concentrations in the urine of MOH patients and in the serum of rats with neuropathic pain. The aim of this study was to compare the serum levels of lipocalin-type Prostaglandin D2 synthase (L-PGDS), Vitamin D-binding protein (VDBP), apolipoprotein E (APOE) and apolipoprotein A1 (APOA1) in MOH patients and healthy individuals, further exploring their relationship with cutaneous pain thresholds (CPTs) in the territories innervated by the trigeminal nerve.
Learn More >Tail amputation by tail docking or as an extreme consequence of tail biting in commercial pig production potentially has serious implications for animal welfare. Tail amputation causes peripheral nerve injury that might be associated with lasting chronic pain. The aim of this study was to investigate the short- and long-term effects of tail amputation in pigs on caudal DRG gene expression at different stages of development, particularly in relation to genes associated with nociception and pain. Microarrays were used to analyse whole DRG transcriptomes from tail amputated and sham-treated pigs 1, 8, and 16 weeks following tail treatment at either 3 or 63 days of age (8 pigs/treatment/age/time after treatment; = 96). Tail amputation induced marked changes in gene expression (up and down) compared to sham-treated intact controls for all treatment ages and time points after tail treatment. Sustained changes in gene expression in tail amputated pigs were still evident 4 months after tail injury. Gene correlation network analysis revealed two co-expression clusters associated with amputation: Cluster A (759 down-regulated) and Cluster B (273 up-regulated) genes. Gene ontology (GO) enrichment analysis identified 124 genes in Cluster A and 61 genes in Cluster B associated with both "inflammatory pain" and "neuropathic pain." In Cluster A, gene family members of ion channels e.g., voltage-gated potassium channels (VGPC) and receptors e.g., GABA receptors, were significantly down-regulated compared to shams, both of which are linked to increased peripheral nerve excitability after axotomy. Up-regulated gene families in Cluster B were linked to transcriptional regulation, inflammation, tissue remodeling, and regulatory neuropeptide activity. These findings, demonstrate that tail amputation causes sustained transcriptomic expression changes in caudal DRG cells involved in inflammatory and neuropathic pain pathways.
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