Variability In Pain Sensitivity Research Articles

The role of diurnal variation in development of musculoskeletal pain during prolonged standing

BackgroundResearch suggests mechanical changes occur to the body over the course of the day including shrinking of the intervertebral disc height which can increase rotational stiffness and rigidity of the spinal column. Further, pain sensitivity has been observed to fluctuate throughout the day, suggesting variations in pain sensitivity. Previous work has identified biomechanical and neuromuscular features related to the development of musculoskeletal pain during prolonged standing; however, many protocols have not controlled for time of day. Research questionDoes the time of day (i.e., diurnal variation) have an effect on the common neuromuscular and biomechanical variables characterizing the development of standing musculoskeletal pain in a two-hour prolonged standing protocol? MethodsA convenience sample of 20 healthy young adults (10 female and 10 male) completed two 2-hour prolonged standing bouts (8:00 a.m. and 8:00 p.m.) on separate days. Visual analogue scales were used to measure pain perception of the low back, legs, and feet throughout each protocol. Neuromuscular control was measured using surface EMG on muscles of the trunk and lower extremities. Postural sway was captured using measures of joint range of motion, and the analysis of center of pressure trajectory data using a force plate. ResultsDiurnal variation was observed to influence the development of musculoskeletal pain. Specifically, pain perception was found to be increased in the evenings as more participants were classified as pain developers in the PM sessions, and mean leg and foot pain perceptions were higher in the evening. Reduced postural sway patterns, and elevated co-contraction indices were found to be associated with the development of pain. SignificanceThese results suggest that future research assessing standing-pain protocols should control for time of day. Additionally, further research is warranted to explore the mechanistic causes of the development of standing pain.

Bridging the genetic gulf: a deep dive into neurotransmission, pharmacogenomics, and genetic variations for optimal pain management

Pain embodies a complex sensory experience influenced by a medley of biological, psychological, and genetic. Pain perception can be classed into four main categories: nociceptive pain, neuropathic pain, acute pain, and chronic pain. Genetic polymorphisms, which are basically genetic variations in DNA sequences, have a part to play in the neurotransmission pathways associated with pain perception and the ultimate effectiveness of pain management interventions. Learning about the effects of genetics on neurotransmission in pain management offers a fresh viewpoint on individual variations in pain sensitivity, response to treatment, and the development of personalised approaches to pain management. A closer look at the relationship between genetic polymorphisms and neurotransmission provides a better understanding deep down at the genetic level. These chemical messengers, neurotransmitters, help pass signals between nerve cells; they are essential for pain processing and modulation. Differences in genetic makeup in neurotransmitter-related genes could change how these genes express, function, and regulate, thus changing how humans perceive pain and respond to pain management interventions. The conjunction of neurotransmission and pharmacogenomics forms a unique convergence, composing a narrative that discloses the percipient influence of individual genetic differences on neural communication and responses to pharmaceuticals. These genetic variations elaborately construct the molecular architecture supervising neurotransmitter release, receptor interactions, and enzymatic processes within the nervous system. In this review, the convergence of neurotransmission, pharmacogenomics, and genetic variations illuminates a pivotal realm in healthcare. Genetic variations intricately influence neurotransmission pathways, moulding individual responses to pharmacological interventions. This intersection not only underscores the complexity of human biology but also holds the promise of personalised healthcare solutions. Recognising subtle genetic variations in neurotransmission and pharmacogenomics opens the door to precision medicine, tailoring treatments to individual genetic codes and revolutionising our approach to medical care.

Cultural variability in pain perception: A review of cross-cultural studies

Pain perception is a complex phenomenon influenced by biological, psychological, and socio-cultural factors. This review presents a review of cross-cultural studies investigating the cultural variability in pain perception. Understanding how different cultures experience and express pain is crucial for providing effective healthcare interventions and improving patient outcomes. Cross-cultural research reveals significant variations in pain perception across different cultural groups. Cultural beliefs, values, and practices shape individuals' interpretation and expression of pain. Studies have shown that cultural norms dictate whether individuals express pain openly or suppress it, impacting their willingness to seek medical help and their response to pain management strategies. Furthermore, cultural differences in pain expression extend to non-verbal cues and pain-related behaviors. For instance, some cultures may perceive stoicism as a virtue, leading individuals to underreport their pain levels, while others may encourage vocal expressions of pain. These cultural nuances influence healthcare professionals' interpretation of patients' pain experiences and may lead to disparities in pain assessment and treatment. Moreover, cultural factors interact with biological mechanisms to modulate pain perception. Genetic predispositions and physiological differences contribute to variations in pain sensitivity among different ethnic groups. However, cultural factors such as coping mechanisms, social support networks, and cultural rituals also play a significant role in shaping individuals' pain experiences. The impact of culture on pain perception extends beyond individual differences to influence healthcare systems and policies. Cultural competency training for healthcare providers is essential to address disparities in pain management and ensure culturally sensitive care. Additionally, integrating cultural factors into pain assessment tools and treatment protocols can improve the accuracy of pain assessment and enhance patient care outcomes. Cultural variability significantly influences pain perception, expression, and management. Cross-cultural studies provide valuable insights into the complex interplay between culture, biology, and socio-cultural factors in shaping individuals' experiences of pain. Recognizing and addressing cultural differences in pain perception is essential for delivering equitable and effective healthcare services worldwide.

Multimodal covarying brain patterns mediate genetic and psychological contributions to individual differences in pain sensitivity.

Individuals vary significantly in their pain sensitivity, with contributions from the brain, genes, and psychological factors. However, a multidimensional model integrating these factors is lacking due to their complex interactions. To address this, we measured pain sensitivity (ie, pain threshold and pain tolerance) using the cold pressor test, collected magnetic resonance imaging (MRI) data and genetic data, and evaluated psychological factors (ie, pain catastrophizing, pain-related fear, and pain-related anxiety) from 450 healthy participants with both sexes (160 male, 290 female). Using multimodal MRI fusion methods, we identified 2 pairs of covarying structural and functional brain patterns associated with pain threshold and tolerance, respectively. These patterns primarily involved regions related to self-awareness, sensory-discriminative, cognitive-evaluative, motion preparation and execution, and emotional aspects of pain. Notably, pain catastrophizing was negatively correlated with pain tolerance, and this relationship was mediated by the multimodal covarying brain patterns in male participants only. Furthermore, we identified an association between the single-nucleotide polymorphism rs4141964 within the fatty acid amide hydrolase gene and pain threshold, mediated by the identified multimodal covarying brain patterns across all participants. In summary, we suggested a model that integrates the brain, genes, and psychological factors to elucidate their role in shaping interindividual variations in pain sensitivity, highlighting the important contribution of the multimodal covarying brain patterns as important biological mediators in the associations between genes/psychological factors and pain sensitivity.

The overgeneralization of pain-related fear in individuals with higher pain sensitivity: A behavioral and event-related potential study

Fear generalization contributes to the development and maintenance of pain. Pain sensitivity has been proposed to predict the strength of fear responses to aversive stimuli. However, whether individual variation in pain sensitivity affects pain-related fear generalization and its underlying cognitive processing remains unclear. To address this gap, we recorded behavioral and event-related potential (ERP) data among 22 high pain sensitivity (HPS) and 22 low pain sensitivity (LPS) healthy adults when exposed to a fear generalization paradigm. The behavioral results indicate that the HPS group displayed higher unconditioned stimulus expectancy and greater fear, arousal, and anxiety ratings to conditioned stimulus and generalization stimulus than the LPS group (all p values < 0.05). The ERP results showed that the HPS group exhibited a larger late positive potential evoked by GS2, GS3 and CS- (all p < 0.005) but a smaller N1 evoked by all CS and GSs (all p values < 0.05) relative to the LPS group. These findings suggest that individuals with a high level of pain sensitivity allocate more attention resources to pain-related threatening stimuli, which contributes to an overgeneralization of pain-related fear.

Painful Cutaneous Laser Stimulation for Temporal Summation of Pain Assessment

Variability in pain sensitivity arises not only from the differences in peripheral sensory receptors but also from the differences in central nervous system (CNS) pain inhibition and facilitation mechanisms. Temporal summation of pain (TSP) is an experimental protocol commonly used in human studies of pain facilitation but is susceptible to confounding when elicited with the skin-contact thermode, which adds the responses of touch-related Aβ low-threshold mechanoreceptors to nociceptive receptors. In the present study, we evaluate an alternative method involving the use of a contactless cutaneous laser for TSP assessment. We show that repetitive laser stimulations with a one second inter-stimulus interval evoked reliable TSP responses in a significant proportion of healthy subjects (N = 36). Female subjects (N = 18) reported greater TSP responses than male subjects confirming earlier studies of sex differences in central nociceptive excitability. Furthermore, repetitive laser stimulations during TSP induction elicited increased time-frequency electroencephalography (EEG) responses. The present study demonstrates that repetitive laser stimulation may be an alternative to skin-contact methods for TSP assessment in patients and healthy controls. PerspectiveTemporal summation of pain (TSP) is an experimental protocol commonly used in human studies of pain facilitation. We show that contactless cutaneous laser stimulation is a reliable alternative to the skin contact approaches during TSP assessment.

Characteristics and Outcomes of Patients Receiving Physical Therapy for Low Back Pain with a Nociplastic Pain Presentation: A Secondary Analysis.

Individuals with low back pain (LBP) may be classified based on mechanistic descriptors, such as a nociplastic pain presentation (NPP). The purpose of this secondary analysis was to examine the frequency and characteristics of patients with a NPP referred to physical therapy with LBP. Additionally, we characterized patients with LBP meeting the criteria for NPP by demographic, clinical, psychological, and pain sensitivity variables. Finally, we examined short- and long-term clinical outcomes in patients with a NPP compared to those without a NPP. Patients referred to physical therapy for LBP completed the Patient Self-report Survey for the Assessment of Fibromyalgia. Participants were categorized as "LBP with NPP" or "LBP without NPP" based on the threshold established in this measure. A rank sum test examined for differences in pain-related psychological factors and pressure-pain threshold between groups. Next, a Friedman test examined if LBP intensity and disability trajectories differed by groups at one and six months after initiation of physical therapy. 22.2% of patients referred to physical therapy for LBP met the criteria for a NPP. Patients with a NPP reported significantly greater disability, pain catastrophizing, depression, anxiety, and somatization compared to individuals without a NPP (p < 0.05). Pressure-pain threshold did not differ between groups (p > 0.05). Individuals with LBP with a NPP demonstrated nonsignificant, small to medium reductions in pain and disability at one and six months. Individuals experiencing LBP without a NPP demonstrated significant reductions in pain and disability in the short- and long term. Patients with LBP with a NPP displayed greater negative pain-related psychological factors but similar pain sensitivity compared to LBP without NPP.

A52 SEX DIFFERENCES IN POST-INFLAMMATORY VISCERAL PAIN IN A MOUSE MODEL OF INFLAMMATORY BOWEL DISEASE (IBD)

Abstract Background Inflammatory bowel diseases (IBD) are chronic inflammatory disorders of the gastrointestinal tract. Despite achieving endoscopic remission, up to 50% of IBD patients continue to experience chronic abdominal pain, with female patients displaying an increased prevalence. The reason underlying these differences in pain perception is unknown, but the influence of sex hormones represents an important biological source for variability in pain sensitivity. To date, few studies have examined sex differences in chronic visceral pain in IBD. Purpose Examine sex-specific differences in post-inflammatory chronic visceral pain in IBD. Method We used the post-inflammatory DSS mouse model of chronic visceral pain. Ovariectomy was performed to study the effects of estrogen deficiency; sham surgery was performed as a control. Male, cycling female and ovariectomized female mice were given 2.5% DSS for five days and allowed to recover for 5 weeks. Somatic pain was evaluated using the hot plate and von Frey hair tests. Visceral pain was evaluated using the visceral motor reflex (VMR) to colorectal distension five weeks after DSS treatment. Visceral and somatic pain testing in cycling females was performed in diestrus. Result(s) Male, cycling female and ovariectomized female mice given DSS initially lost weight when compared to controls (p&amp;lt;0.0001). Cycling females displayed significantly decreased colitis severity when compared to males [Disease Activity Index at Day 12: 1.41 ± 0.41 cycling females, n=12; 4.41 ± 0.31 males, n=12; p&amp;lt;0.001] but increased severity compared to ovariectomized females [Disease Activity Index at Day 12: 2.0 ± 0.41 ovariectomized females, n=13; 4.77 ± 0.6 cycling females, n=13, p=0.0005]. Increased visceral hypersensitivity was seen in post-inflammatory cycling females compared to post-inflammatory males [VMR at 60mmHg, post-inflammatory cycling females 0.10 ± 0.016, n=10; post-inflammatory males 0.07 ± 0.007, n=10; p=0.032] and post-inflammatory ovariectomized females [VMR at 60mmHg, post-inflammatory sham females 0.072 ± 0.005, n=8; post-inflammatory ovariectomized females 0.047 ± 0.005, n=8; p=0.019]. Thermal hyperalgesia and mechanical allodynia were similar across all groups. Conclusion(s) These data suggest that estrogen plays an important role in the severity of colitis severity and post-inflammatory visceral pain. Understanding sex-specific differences in post-inflammatory visceral pain in IBD may allow us to define novel therapeutic approaches for IBD patients. Disclosure of Interest None Declared

VARIABILIDAD DE LOS GENES PDYN Y OPRK1 EN CUATRO POBLACIONES ARGENTINAS Y SU ASOCIACIÓN CON VARIABLES CLÍNICAS RELACIONADAS AL DOLOR AGUDO POST-QUIRÚRGICO

Several population studies showed an association between variation in pain sensitivity and genetic polymorphisms located in Prodynorphin (PDYN) and Kappa Opioid Receptor (OPRK1) human genes. We analysed polymorphisms of these two genes to characterise their variation in Argentinian populations, as well as to evaluate their association with acute pain sensitivity. We studied 11 genetic markers in individuals from four locations in Argentina (Ciudad Autónoma de Buenos Aires, La Plata, Resistencia, and Misión Nueva Pompeya), calculated the population parameters, and evaluated the possible association among pain sensitivity, clinical, and genetic variables through a Generalised Estimating Equation model. High linkage disequilibrium was observed in the four populations for both genes, and significant differences were found among frequencies of Argentinian populations and those from other continents reported in the 1000 Genomes Project. Four PDYN gene polymorphisms from 3´ untranslated region and exon 4 showed association with acute pain sensitivity. One genotype of each of these polymorphisms was associated with a higher pain sensitivity, probably related with the activation of the N-methyl-D-aspartate (NMDA) receptors. We found a strong association with acute pain for the following clinical variables: 1) time after surgery, 2) intravenous klosidol supplied every 8 h, and 3) type of incision. Our results highlight the importance of a regional study of genetic variants which influence pain sensitivity and analgesic response. Key words: human populations, pain sensitivity, acute pain, genetic polymorphisms, genetic structure

Effect of Exercises on Central and Endocrine System for Pain Modulation in Primary Dysmenorrhea.

Dysmenorrhea is the term for describing complex menstrual flow and painful spasmodic cramps during menstruation, and pain without any pathology is considered Primary Dysmenorrhea (PD). It is the most frequent ailment among women of all ages and races. The pain is dull and throbbing in character and occurs in the lower back and abdomen. Symptoms commonly appear 6 to 12 months after menarche, with the most significant incidence in the late teen and early twenties. Physical exercise is nearly a new non-medical intervention to relieve PD associated pain. Aerobics, stretching and Resistive exercises for 8-12 weeks, either supervised or unsupervised, relieves pain. Exercises are believed to cause hormonal changes in the uterine lining, which reduces PD symptoms. Researchers have presumed different pain-relieving methods, ranging from non-opioids to opioids to hormonal for variations in pain sensitivity. Exercise-induced analgesia provides the central pathway as the primary mechanism for pain reduction while, another way to reducing pain in PD may be a hormonal interaction. The hormonal changes causing exercise-induced pain modulation during the menstruation cycle is not clearly understood and the interaction and activation of all the central and endocrine components, which is a complex mechanism, is also not explained clearly. This study briefly reviews the physiological mechanism of Exercise-induced analgesia and its potent roles in controlling the pathogenesis of PD for pain relief.

Does human serotonin-1A receptor polymorphism (rs6295) code for pain and associated symptoms in fibromyalgia syndrome?

Genetic predisposition may play an important role in the development of fibromyalgia syndrome (FMS). Serotonin is known to be involved in pain modulation and serotonin-1A receptor plays a considerable role in determining the central 5-HT tone. Consequently, variation in 5-HT1A receptor gene (HTR1A) may be responsible for inter-individual variability in pain sensitivity and other clinical symptoms of FMS. Therefore, the objectives of this research work were to study the gene polymorphism of 5-HTR1A gene and to explore the correlation between rs6295 genotype (-1019C/G HTR1A) and duration of pain, pain intensity and pain related depression and anxiety, if any, in FMS. 5-HTR1A genotype for the C(-1019)G polymorphism was typed in 62 patients with FMS and 42 healthy subjects. Present pain intensity, components of pain and pain related depression and anxiety were assessed using the numerical pain rating scale, McGill pain questionnaire and Hamilton depression and anxiety rating scale respectively. 5-HTR1A gene was represented by three different genotypes, homozygous C/C, heterozygous C/G and homozygous G/G. Analysis of the 5-HTR1A gene showed a frequency of 58%, 31% and 11% for the C/C, C/G and G/G genotypes, respectively in FMS group. This proportion was 69%, 23% and 8% in healthy subjects. No significant correlation was observed between 5-HTR1A gene polymorphism and pain and related symptoms in FMS patients. To the best of our knowledge this is the first study which investigated the correlation between the 5-HTR1A gene polymorphism and pain intensity, the affective component of pain, pain related depression and anxiety in FMS.

Individual Variation in Pain Sensitivity and Implicit Negative Bias Toward Pain.

Although previous studies have shown the linkage between pain sensitivity and pain-related cognitions, this study investigated whether individual variation in pain sensitivity is related to implicit negative bias toward pain. Two groups of participants with low (LPS) or high (HPS) pain sensitivity (LPS group: n = 33; HPS group: n = 31) were recruited based on their scores on pain sensitivity questionnaires. This categorization was later confirmed via pain ratings to electrical stimulations. Implicit negative bias toward pain was assessed using the Implicit Association Test (IAT) involving target (pain and nonpain) and attribute (negative and neutral-affect) concept words. Behavioral and event-related potential responses for congruent and incongruent pairings during the IAT were compared between the LPS and HPS groups. Relative to the LPS group, participants in the HPS group exhibited greater D-score (Cohen's d = 0.364, p = .004). Event-related potential results showed that, although P3 amplitudes to congruent and incongruent pairings differed significantly for the HPS group (Cohen's d = 0.757, p < .001), this difference was not observed for the LPS group (Cohen's d = 0.089, p = .29). Mediation analysis further revealed that the IAT effect on P3 responses accounted for 17.58% of the association between pain sensitivity and D-score (confidence interval = [0.009-0.051]). Individual variation in pain sensitivity relates to implicit negative bias. This linkage is partially accounted for by the electrophysiological response that has been related to cognitive process of stimulus evaluation and categorization. Pain treatment might benefit from techniques designed to alter implicit bias.

Preoperative Pressure Pain Threshold Is Associated With Postoperative Pain in Short-Stay Anorectal Surgery: A Prospective Observational Study.

BACKGROUND:Postoperative pain management is key for patient satisfaction. Pressure pain threshold (PPT) has been studied in some surgical cohorts but has not been studied in relationship to acute postoperative pain in short-stay patients undergoing anorectal surgery. We hypothesized that preoperative finger PPT measurements can identify respective patients with higher postoperative pain. Aiming to understand the relationship with subjective postoperative pain perception, we tested the hypotheses that preoperative PPT is associated with postoperative Visual Analog Scale (VAS) pain scores and correlates with postoperative analgesic consumption in short-stay patients undergoing anorectal surgery.METHODS:We prospectively assessed preoperative PPT in a cohort undergoing anorectal surgery, known as a moderately to severely painful procedure. Linear mixed-effects models were used to assess the relationship with postoperative VAS pain scores at 1 and 3 days as well as 4 weeks postoperatively. Logistic regression was used to study the relationship with additional postoperative analgesic consumption.RESULTS:We studied 128 patients and found that preoperative PPT is significantly associated with postoperative pain (P value for interaction = .025). Logistic regression modeling additionally revealed an association between the preoperative PPT and the need for additional postoperative analgesics, with odds of requiring additional analgesia decreasing by about 10% for each 1-point increase in PPT (odds ratio [OR] = 0.90; 95% confidence interval [CI], 00.81–0.98; P = .012).CONCLUSIONS:Preoperative finger PPT is associated with postoperative pain and might help identify patients who are at risk of developing more severe postoperative pain on anorectal surgery. Especially in ambulatory and short-stay settings, this approach can help to address patients’ high variability in pain sensitivity to facilitate appropriate postoperative analgesia, timely discharge, and prevent readmission.

Genetic mapping in Diversity Outbred mice identifies a Trpa1 variant influencing late-phase formalin response.

Identification of genetic variants that influence susceptibility to pain is key to identifying molecular mechanisms and targets for effective and safe therapeutic alternatives to opioids. To identify genes and variants associated with persistent pain, we measured late-phase response to formalin injection in 275 male and female Diversity Outbred mice genotyped for over 70,000 single nucleotide polymorphisms. One quantitative trait locus reached genome-wide significance on chromosome 1 with a support interval of 3.1 Mb. This locus, Nociq4 (nociceptive sensitivity quantitative trait locus 4; MGI: 5661503), harbors the well-known pain gene Trpa1 (transient receptor potential cation channel, subfamily A, member 1). Trpa1 is a cation channel known to play an important role in acute and chronic pain in both humans and mice. Analysis of Diversity Outbred founder strain allele effects revealed a significant effect of the CAST/EiJ allele at Trpa1, with CAST/EiJ carrier mice showing an early, but not late, response to formalin relative to carriers of the 7 other inbred founder alleles (A/J, C57BL/6J, 129S1/SvImJ, NOD/ShiLtJ, NZO/HlLtJ, PWK/PhJ, and WSB/EiJ). We characterized possible functional consequences of sequence variants in Trpa1 by assessing channel conductance, TRPA1-TRPV1 interactions, and isoform expression. The phenotypic differences observed in CAST/EiJ relative to C57BL/6J carriers were best explained by Trpa1 isoform expression differences, implicating a splice junction variant as the causal functional variant. This study demonstrates the utility of advanced, high-precision genetic mapping populations in resolving specific molecular mechanisms of variation in pain sensitivity.

Catechol-O-Methyltransferase Val158Met Polymorphism Is Associated with Anxiety, Depression, and Widespread Pressure Pain Sensitivity in Women with Chronic, but Not Episodic, Migraine.

To analyze the association between the rs4680 catechol-O-methyltransferase Val158Met polymorphism and to determine the association of this polymorphism with clinical, psychological, and pain sensitivity variables in women with episodic or chronic migraine. Fifty women with episodic migraine, 50 with chronic migraine, and 50 matched healthy women participated. After amplifying the Val158Met polymorphism by polymerase chain reaction, we assessed genotype frequencies and allele distributions. Participants were classified according to the Val158Met polymorphism genotype into Val/Val, Val/Met, or Met/Met. A headache diary was used for collecting migraine pain features. Disability was assessed with the Migraine Disability Assessment Scale, trait/state anxiety levels with the State-Trait Anxiety Inventory, and depression/anxiety with the Hospital Anxiety and Depression Scale. Pressure pain thresholds (PPTs) were bilaterally assessed over the temporalis, the upper trapezius, the second metacarpal, and the tibialis anterior. The distribution of the rs4680 Val158Met genotype was not significantly different between women with and without migraine (P = 0.157). No differences in migraine features were found to be dependent on the Val158Met genotype. Women with the Met/Met genotype showed higher migraine-related disability than those with the Val/Val or Val/Met genotype in both migraine groups (P < 0.01). Women with chronic, but not episodic, migraine with the Met/Met genotype exhibited higher depressive and anxiety levels and lower PPTs than those with the Val/Val or Val/Met genotype. The Val158Met rs4680 polymorphism does not appear to be involved in predisposition to suffer from migraine; however, this genetic factor may be involved in the phenotypic expression of chronic migraine, as anxiety, depression, and widespread pressure pain sensitivity were greater in those women with chronic, but not episodic, migraine with the Met/Met genotype.

The Molecular Approach in Pain Management and Improve Aesthetics Modules

In this review we discussed the developments in pain research and defined how the area is building on this progress to understand how pain is recorded. We likewise speculated on how these insights could lead to even more effective and specific analgesics. Methods: Results: Pain has been defined as an unpleasant sensory and emotional experience associated with actual or potential damage, or described in terms of such damage. It is primarily a protective mechanism designed to avoid tissue damage, is very subjective in nature with wide interpatient variability in pain sensitivity, and has been described as “a conscious experience to which the outside observer is not privy”. Despite the widespread prevalence of pain, it is inadequately managed due to a lack of appropriate formal physician training that is coupled with concerns regarding the addictive liabilities of the opioids, a global phenomenon described as “opiophobia”. On the other hand, patients may tolerate pain to an extent that can prevent effective treatment and result in long-term nerve damage that is frequently irreversible. Keywords: molecular approach, pain management, aesthetics modules. language controlled studies assessing molecular approach in pain management and improve aesthetics modules published to 2018. Our search was limited to only Human subject with English language. Computerized databases were searched for English- Moreover, references of identified studies were manually searched for more relevant articles.

Individual Variation in Pain Sensitivity and Conditioned Pain Modulation in Acute Low Back Pain: Effect of Stimulus Type, Sleep, and Psychological and Lifestyle Factors

Generalized hyperalgesia and impaired pain modulation are reported in chronic low back pain (LBP). Few studies have tested whether these features are present in the acute phase. This study aimed to test for differences in pain presentation in early-acute LBP and evaluate the potential contribution of other factors to variation in sensitivity. Individuals within 2 weeks of onset of acute LBP (n = 126) and pain-free controls (n = 74) completed questionnaires related to their pain, disability, behavior, and psychological status before undergoing conditioned pain modulation (CPM) and pain threshold (heat, cold, and pressure) testing at the back and forearm/thumb. LBP participants were more sensitive to heat and cold at both sites and pressure at the back than controls, without differences in CPM. Only those with high-pain (numeric rating scale ≥4) were more sensitive to heat at the forearm and pressure at the back. Four subgroups with distinct features were identified: “high sensitivity,” “low CPM efficacy,” “high sensitivity/low CPM efficacy,” and “low sensitivity/high CPM efficacy.” Various factors such as sleep and alcohol were associated with each pain measure. Results provide evidence for generalized hyperalgesia in many, but not all, individuals during acute LBP, with variation accounted for by several factors. Specific pain phenotypes provide candidate features to test in longitudinal studies of LBP outcome. PerspectiveSensory changes indicative of increased/decreased central processing of pain and nociceptive input presented differently between individuals with acute LBP and were related to factors such as sleep and alcohol. This may underlie variation in outcome and suggest potential for early identification of individuals with poor long-term outcome.

Conditioned Pain Modulation and Pressure Pain Sensitivity in the Adult Danish General Population: The DanFunD Study.

Data from this large population-based study provide new insight into the gender and age variation in pain sensitivity and CPM response. Decreased CPM potency and increased pain sensitivity in female participants were found, emphasizing the need to improve the understanding of its clinical consequences.

Variation in pressure pain threshold correlates with rheumatoid arthritis disease activity, not with the inflammatory parameters

Background Pain is a chief symptom of rheumatoid arthritis (RA) indicating the disease flare. Variation in pain sensitivity with inflammatory load may assist in measuring the disease activity. Tender joint counts, one of the currently used pain measures, is more a measure of active joints rather than the pain. Although visual analogue scale (VAS) reflects the perception of pain, it does not indicate the true change in the pain. Aim To evaluate whether pressure pain threshold (PPT) represents disease activity by comparing it with DAS-28 and inflammatory markers like ESR and CRP. Materials and methods Twenty freshly diagnosed female RA subjects were recruited after careful exclusion of patients with fibromyalgia (FM). They were assessed for tender joint count, swollen joint count, visual analogue scale (pain/general health), ESR, and CRP during their three consecutive follow-up of six week intervals. PPT was measured using digital algometer at three pairs of joint areas (metacarpophalangeals, wrists and most inflamed joint) and at three FM tender point sites (sub-occipital, mid-trapezius and buttocks). Arithmetic mean of all areas (average PPT) and average PPT of FM points were calculated. The data was analyzed using Pearson correlation co-efficient, Deming regression analysis and correlation of change. Results Average PPT and PPT of most inflamed joint have moderate to large correlation with DAS-ESR and DAS-CRP. In contrast, small to trivial correlation with ESR and CRP was noted. Similar results were seen for FM tender point sites. Conclusion PPT at inflamed as well as at FM sites correlates significantly with DAS-ESR and DAS-CRP. It does not correlate independently with changes in inflammatory parameters ESR and CRP. PPT in conjuncture with DAS could be useful in routine clinical practice to measure the pain as well disease activity, in RA patients .

Association of μ-opioid receptor gene polymorphism (A118G) with variations in fentanyl analgesia consumption after total abdominal hysterectomy in female Egyptian patients

Opioid analgesics are widely used for the treatment of moderate to severe pain. However, the analgesic efficacy of opioids is well known to vary widely among individuals, making it difficult to predict optimal pain management for each patient. The current clinical study was designed to investigate the association of the A118G single nucleotide polymorphism of the μ-opioid receptor gene with the individual variation in pain sensitivity and fentanyl consumption with patient-controlled analgesia (PCA) in 60 adult female Egyptian patients after total abdominal hysterectomy. All patients received general anesthesia according to the same protocol. During the first 24 h after surgery, pain was assessed using a visual analogue scale. In addition, total amount of fentanyl consumption, sedation score, and any other side effects of opioids were recorded; the A118G single nucleotide polymorphism of the μ-opioid receptor gene was detected by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Our main finding was that in Egyptian gynecological patients, subjects homozygous for the 118G allele needed more fentanyl (488.5 ± 23.91 μg) for 24-h postoperative analgesia than 118A homozygotes (359.82 ± 19.63 μg) and heterozygotes (400± 8.99 μg) (P = 0.001). There was no association of G or A allele and opioid side effects. This study may provide support for the potential use of genetic data in predicting patient’s individual fentanyl doses for adequate postoperative pain control.