The Mediating Role of Pain Cognitions and Pain Sensitivity in the Treatment Effect of Perioperative Pain Neuroscience Education in People Undergoing Surgery for Lumbar Radiculopathy.

Though perioperative pain neuroscience education (PPNE) positively influences patients' surgical outcomes, little is known about the mechanisms behind this treatment's success. Therefore, this study aims to evaluate the potential mediating role of pain cognitions and pain sensitivity in the treatment effect of PPNE on postoperative quality of life in people undergoing surgery for lumbar radiculopathy. This secondary analysis uses data from 120 participants of a randomized controlled trial who were randomized to receive either PPNE or perioperative biomedical education before undergoing surgery for lumbar radiculopathy. Quality of life was assessed 1-year postsurgery using the short form 36-item health survey (SF36) physical and mental component scores. Potential mediators included pain cognitions (ie, kinesiophobia, pain catastrophizing, and hypervigilance) and pain sensitivity (ie, endogenous nociceptive modulation), assessed 6 weeks postsurgery. Mediation models were constructed using structural equation modeling, and 95% confidence intervals (CIs) were calculated using 10,000 bootstrap samples. Analyses show a significant total effect for PPNE (estimate = .464, 95% CI [.105, .825]) and a significant indirect effect via pain catastrophizing on the SF36 physical component (estimate = .124, 95% CI [.001, .293]). No mediating effect was found through the remaining pain cognitions or pain sensitivity measures. Also, no potential mediators were identified for the treatment effect of PPNE on the SF36 mental component. Our findings suggest that pain catastrophizing mediates the treatment effect of PPNE on physical health-related quality of life in people undergoing surgery for lumbar radiculopathy. PERSPECTIVE: This secondary analysis identified pain catastrophizing as a mediator for PPNE in people undergoing surgery for lumbar radiculopathy. More so, its findings indicate that this educational intervention can enhance the postoperative physical health-related quality of life of these patients by addressing their catastrophizing thoughts. TRIAL REGISTRATION: Clinicaltrials.gov (NCT02630732).

Influence of Preoperative Pain, Cognitions, and Quantitative Sensory Testing Measures on the Effects of Perioperative Pain Neuroscience Education for People Receiving Surgery for Lumbar Radiculopathy: Secondary Analysis of a Randomized Controlled Trial.

OBJECTIVE: To explore whether preoperative pain intensity, pain cognitions, and quantitative sensory measures influence the established effectiveness of perioperative pain neuroscience education (PPNE) on health-related quality of life at 1 year after surgery for lumbar radiculopathy. DESIGN: Secondary analysis of a triple-blinded randomized controlled trial. METHODS: Participants (n = 90) were Dutch-speaking adults (18-65 years) who were scheduled for surgery for lumbar radiculopathy in 3 Belgian hospitals. They were randomized (1:1) to receive PPNE (n = 41) or perioperative biomedical education (n = 49). Linear mixed models were built for health-related quality of life (ie, SF-6D utility values, Physical and Mental Component of the 36-item Short Form Health Survey) using the following independent variables: therapy, time, and preoperative scores for back and leg pain intensity, pain catastrophizing, kinesiophobia, hypervigilance, and quantitative sensory measures. RESULTS: The impact of PPNE on SF-6D utility values over time was influenced by kinesiophobia (F = 3.30, P = .02) and leg pain intensity (F = 3.48, P = .02). Regardless of the intervention, back pain intensity negatively influenced SF-6D values over time (F = 3.99, P = .009). The Physical Component scores were negatively impacted by back pain intensity (F = 9.08, P = .003) and were influenced over time by leg pain intensity (F = 2.87, P = .04). The Mental Component scores were negatively impacted by back pain intensity (F = 6.64, P = .01) and pain catastrophizing (F = 5.42, P = .02), as well as hypervigilance (F = 3.16, P = .03) and leg pain intensity (F = 3.12, P = .03) over time. CONCLUSION: PPNE may be more effective than perioperative biomedical education in improving postoperative health utility values in patients who reported higher kinesiophobia and leg pain intensity before surgery for lumbar radiculopathy. J Orthop Sports Phys Ther 2024;54(4):1-10. Epub 8 January 2024. doi:10.2519/jospt.2024.12051.

Effect of perioperative pain neuroscience education in people undergoing surgery for lumbar radiculopathy: a multicentre randomised controlled trial.

BACKGROUND: Perioperative education should be improved to decrease unfavourable outcomes after lumbar surgery. This trial aimed to compare effectiveness in terms of pain, quality of life, pain cognition, surgical experience, healthcare use, work resumption, and cost-effectiveness of perioperative pain neuroscience education (PPNE) vs traditional biomedical education (perioperative biomedical education [PBE]) in people undergoing surgery for lumbar radiculopathy. METHODS: In this multicentre RCT (ClinicalTrials.gov: NCT02630732), patients undergoing surgery for lumbar radiculopathy in three Belgian hospitals were randomised to receive PPNE or PBE. Both groups received one preoperative and one postoperative one-to-one education session and a booklet (balanced interventions), with an essentially different content (PPNE: biopsychosocial; PBE: biomedical). Pain was the primary outcome (Visual Analogue Scales+quantitative sensory testing). Assessments were at 3 days, 6 weeks, and 6 and 12 months after surgery. RESULTS: Between March 2016 and April 2020, participants were randomly assigned to PPNE (n=58) or PBE (n=62). At 12 months, PPNE did not lead to significantly better pain outcomes, but it did result in more favourable 36-item Short Form Health Survey physical component (additional increase: 46.94; 95% confidence interval [CI]: 14.16-79.73; medium effect), Tampa Scale of Kinesiophobia (additional decrease: 3.15; 95% CI: 0.25-6.04; small effect), and Pain Catastrophising Scale (additional decrease: 6.18; 95% CI: 1.97-10.39; medium effect) scores. Females of the PPNE group showed higher probability for work resumption (95% vs 60% in the PBE group). PPNE was cost-effective compared with PBE (incremental costs: €-2732; incremental quality-adjusted life years: 0.012). CONCLUSIONS: Perioperative pain neuroscience education showed superior clinical and cost-effectiveness than perioperative biomedical education in people undergoing surgery for lumbar radiculopathy. CLINICAL TRIAL REGISTRATION: NCT02630732.

Exploring Associations between Healthcare Use and Demographics, Pain and Pain Cognitions in People Scheduled for Surgery for Lumbar Radiculopathy: A Cross-Sectional Study.

This cross-sectional study explored associations between demographics, pain intensity and cognitions on the one hand and healthcare use (HCU) on the other hand in people undergoing surgery for lumbar radiculopathy. HCU during the 2 months preceding surgery was evaluated using a retrospective questionnaire. Demographics included sex, age and level of education and equivalent income. Back and leg pain intensity were evaluated using a visual analogue scale. Pain cognitions were assessed with the Tampa scale of kinesiophobia, the pain catastrophizing scale and the pain vigilance and awareness questionnaire. The sample comprised 120 participants (52% males; 49 years (Quartile (Q)1-Q3: 37.3-57.43)). The number of visits to the general practitioner was associated with sex (incidence rate ratio (IRR) for males = 0.811; p = 0.050), pain catastrophizing (IRR = 1.010; p = 0.041), pain magnification (IRR = 1.058; p = 0.004) and leg pain intensity (IRR = 1.004; p = 0.038). The number of neurosurgeon visits was associated with level of education (IRR moderate education = 1.518; p = 0.016 (reference: low education)). Receiving zero physiotherapy visits was associated with higher back pain intensity (Beta = 0.018; p = 0.028). Highest level of analgesics used was associated with sex (IRR for males = 0.502; p = 0.047) and leg pain (IRR = 1.014; p = 0.034). Only the association between general practitioner visits and pain magnification remained significant in multivariable analyses (IRR = 1.061; p = 0.033). The results suggest a rather indirect relationship between HCU and demographics, pain intensity and cognitions, involving a potential interplay between several patient- and healthcare system-related factors.

Experimental Pain Measurements Do Not Relate to Pain Intensity and Pain Cognitions in People Scheduled for Surgery for Lumbar Radiculopathy.

OBJECTIVE: The present cross-sectional study aims to unravel associations of pain intensity and cognitions with quantitative sensory testing in people scheduled for surgery for lumbar radiculopathy. Additionally, insight will be provided into the presence of dysfunctional nociceptive processing and maladaptive pain cognitions in this population. DESIGN: Cross-sectional study. SETTING: Data from three hospitals in Belgium. SUBJECTS: The final sample comprised 120 participants with lumbar radiculopathy scheduled for surgery, included between March 2016 and April 2019. METHODS: Self-reported pain intensity was assessed on a visual analog scale, and pain cognitions were assessed with self-reported questionnaires (Pain Catastrophizing Scale, Tampa Scale for Kinesiophobia, and Pain Vigilance and Awareness Questionnaire). Quantitative sensory testing (detection thresholds, pain thresholds, temporal summation, and conditioned pain modulation) was evaluated, as well. RESULTS: Evidence was found for the presence of an impaired inhibitory response to nociceptive stimuli and maladaptive pain cognitions in this population. Kinesiophobia was found to be present to a maladaptive degree in the majority of the patients (n = 106 [88%]). Significant, but weak, associations between electrical pain thresholds at the sural nerves and leg pain intensity (sural nerve symptomatic side: r = -0.23; P = 0.01; non-symptomatic side: r = -0.22; P = 0.02) and kinesiophobia levels (sural nerve non-symptomatic side: r = -0.26; P = 0.006) were identified. CONCLUSIONS: Electrical detection thresholds and correlates for endogenous nociceptive facilitation and inhibition were not found to be related to any of the pain cognitions or to pain intensity in people scheduled to undergo surgery for lumbar radiculopathy.

The Predictive Value of Fear Avoidance Beliefs for Outcomes Following Surgery for Lumbar Degenerative Disease: A Systematic Review and Best Evidence Synthesis.

BACKGROUND: Currently, evidence regarding fear avoidance beliefs as potential predictors for lumbar surgery outcomes seems insufficient and strong conclusions are not yet available. OBJECTIVE: This systematic review aimed to evaluate the predictive value of preoperative fear avoidance beliefs for postoperative pain intensity, functional status, and health-related quality of life following surgery for lumbar degenerative disease. STUDY DESIGN: Systematic review and best evidence synthesis. METHODS: An extensive search was performed in PubMed/Medline, EMBASE, PsycINFO, CINAHL and the Cochrane library for articles published up until October 2021. Two independent reviewers performed the screening, data extraction, and quality assessment, with a third independent reviewer consulting to resolve any disagreement. Observational studies that included patients undergoing surgery for lumbar degenerative disease, as well as evaluated fear avoidance beliefs (i.e., pain-related fear, pain catastrophizing, pain anxiety) in relation to a surgical outcome measure (i.e., pain intensity, functional status and health-related quality of life) were included in the review. The CHARMS- and QUIPS-tools were used for data extraction and quality assessment, respectively. A best evidence synthesis was performed resulting in conclusions regarding strong, moderate, conflicting, and limited levels of evidence. RESULTS: A total of 24 studies (n = 17,881) were included in this review. Following best evidence synthesis, 3 included studies reported no significant predictive value of preoperative pain-related fear for postoperative pain intensity resulting in moderate evidence for this relationship. Moderate evidence was also found indicating no significant predictive value of preoperative pain-related fear for postoperative functional status, as 6 out of 8 relevant studies reported this result. Only one study reported on the predictive value of preoperative pain catastrophizing for postoperative health-related quality of life, resulting in limited evidence for the absence of this predictive relationship. All other relationships were found to have conflicting evidence. LIMITATIONS: To evaluate surgical outcome, only patient-reported outcome measures as used by spine registries were included. Thus, our findings cannot be extrapolated to all surgery outcomes following lumbar degenerative disease and should only be interpreted in relation to postoperative pain intensity, functional status, or health-related quality of life. CONCLUSION: Best evidence synthesis showed moderate evidence indicating that preoperative pain-related fear is not a significant predictor for postoperative pain and function following surgery for lumbar degenerative disease. Additionally, limited evidence was found for a lack of predictive value of preoperative pain catastrophizing for postoperative health-related quality of life. As current evidence regarding the predictive value of preoperative fear avoidance beliefs following such a surgery is mixed, further research is required before more definitive conclusions can be made.

Diet/Nutrition: Ready to Transition from a Cancer Recurrence/Prevention Strategy to a Chronic Pain Management Modality for Cancer Survivors?

Evidence for the relationship between chronic pain and nutrition is mounting, and chronic pain following cancer is gaining recognition as a significant area for improving health care in the cancer survivorship population. This review explains why nutrition should be considered to be an important component in chronic pain management in cancer survivors by exploring relevant evidence from the literature and how to translate this knowledge into clinical practice. This review was built on relevant evidence from both human and pre-clinical studies identified in PubMed, Web of Science and Embase databases. Given the relationship between chronic pain, inflammation, and metabolism found in the literature, it is advised to look for a strategic dietary intervention in cancer survivors. Dietary interventions may result in weight loss, a healthy body weight, good diet quality, systemic inflammation, and immune system regulations, and a healthy gut microbiota environment, all of which may alter the pain-related pathways and mechanisms. In addition to being a cancer recurrence or prevention strategy, nutrition may become a chronic pain management modality for cancer survivors. Although additional research is needed before implementing nutrition as an evidence-based management modality for chronic pain in cancer survivors, it is already critical to counsel and inform this patient population about the importance of a healthy diet based on the data available so far.

Diet can exert both analgesic and pronociceptive effects in acute and chronic pain models: a systematic review of preclinical studies.

BACKGROUND: Although diet is an essential aspect of human health, the link between diet and pain is still not well understood. Preclinical animal research provides information to understand underlying mechanisms that allow identifying the needs for human research. OBJECTIVES: This study aims to give a systematic overview of the current evidence from preclinical studies regarding the analgesic and pronociceptive effects of various diets in non-neuropathic, non-cancer, or non-visceral acute and chronic pain models. STUDY DESIGN: A systematic Review. SETTING: This study examined studies that investigate the analgesic and pronociceptive effects of various diets in non-neuropathic, non-cancer, or non-visceral acute and chronic pain models. METHODS: This review was conducted following the PRISMA guidelines and was registered in PROSPERO with the registration number CRD42019133473. The certainty of evidence was examined by a modified GRADE approach. RESULTS: After the screening process twenty-four eligible papers were included in this review. Nineteen studies examined acute pain, nine studies chronic inflammatory pain, and four studies assessed both acute and chronic pain models. LIMITATIONS: Due to the heterogeneity of the included studies, a meta-analysis was not included in this study. CONCLUSIONS: In animal models, excessive saturated, monounsaturated or omega-6 polyunsaturated fat ingestion and diets rich in fats and carbohydrates can decrease pain sensitivity in acute nociceptive pain, whereas it can induce mechanical allodynia and heat hyperalgesia in chronic inflammatory pain. Additionally, diets rich in anti-inflammatory ingredients, as well as a calorie-restricted diet can promote recovery from primary mechanical allodynia and heat hyperalgesia in chronic inflammatory pain.

Health-related quality of life deviations from population norms in patients with lumbar radiculopathy: associations with pain, pain cognitions, and endogenous nociceptive modulation.

PURPOSE: The primary goal of this study was to compare the health-related quality of life (HRQoL) of people with lumbar radiculopathy to age- and sex-adjusted population norms. Additionally, it aimed to explore the associations between the HRQoL difference scores and measures related to pain cognitions, pain intensity, and endogenous nociceptive modulation. METHODS: Using answers from the Short Form 36-item Health Survey and UK population norms, SF-6D difference scores were calculated. A one-sample t test was used to assess the SF-6D difference scores. Univariate and multivariate regression analyses were used to assess the associations between SF-6D difference scores and pain intensity [Visual Analogue Scale (VAS) for back and leg pain], pain cognitions [Pain Catastrophizing Scale (PCS), Tampa Scale for Kinesiophobia (TSK), Pain Vigilance and Awareness Questionnaire (PVAQ)], and correlates for endogenous nociceptive modulation using quantitative sensory testing. RESULTS: One hundred and twenty people with lumbar radiculopathy scheduled for surgery were included in this study. The mean SF-6D difference score of - 0.26 [SD = 0.09] was found to be significantly less than 0 [95%CI: - 0.27 to - 0.24]. Univariate analyses showed a significant influence from PCS, TSK, and PVAQ on the SF-6D difference scores. The final multivariate regression model included PCS and PVAQ, with only PCS maintaining a statistically significant regression coefficient [b = - 0.002; 95% CI: - 0.004 to - 0.001]. CONCLUSION: People diagnosed with lumbar radiculopathy report significantly lower HRQoL scores when compared with age- and sex-adjusted UK norm values. Even though all examined pain cognitions were found to have a significant association, pain catastrophizing showed the most significant relation to the SF-6D difference scores. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier No. NCT02630732. Date of registration: November 25, 2015.

Nutrition/Dietary Supplements and Chronic Pain in Patients with Cancer and Survivors of Cancer: A Systematic Review and Research Agenda.

BACKGROUND: Chronic pain is one of the most often seen, but often undertreated, sequelae in survivors of cancer. Also, this population often shows significant nutritional deficiencies, which can affect quality of life, general health status, and even risk of relapse. Given the influence of nutrition on brain plasticity and function, which in turn is associated with chronic pain in the population with cancer, it becomes relevant to focus on the association between pain and nutritional aspects in this population. OBJECTIVE: To identify relevant evidence regarding nutrition and chronic pain in patients with cancer/survivors of cancer. STUDY DESIGN: Systematic review. METHODS: PubMed, Embase, and Web of Science were systematically searched for interventional and experimental studies that included patients with cancer /survivors of cancer with chronic pain, a nutrition-related observation/examination, and a pain-related outcome. Studies that complied with the inclusion and exclusion criteria were screened for methodological quality and risk of bias by using the Qualsyst (standard quality assessment criteria for evaluating primary research) tool. RESULTS: The 2 included studies entailed uncontrolled trials which examined different nutritional supplements usage in various patients with cancer (breast, gastrointestinal and gynecological  cancers). One study evaluated the effects of vitamin C, but did not report a change in pain outcomes. The other study, looking at the nutritional supplements glucosamine and chondroitin, found an improvement in pain after 12- and 24 weeks. LIMITATIONS: The limitations to the generalization of these results include the insufficient amount of eligible studies and diversity in therapeutic interventions and participant groups. CONCLUSION: The association between nutrition and chronic pain in patients with cancer /survivors of cancer is not well documented. The available studies are uncontrolled, and are therefore limited to draw firm conclusions. Additional research is highly needed, and a research agenda is proposed within this paper.

Influence of Baseline Kinesiophobia Levels on Treatment Outcome in People With Chronic Spinal Pain.

BACKGROUND: Pain neuroscience education (PNE) combined with cognition-targeted exercises is an effective treatment for people with chronic spinal pain (CSP). However, it is unclear why some patients benefit more from this treatment. We expect that patients with more pronounced maladaptive pain cognitions, such as kinesiophobia, might show poorer treatment responses. OBJECTIVE: The objective of this study was to assess the influence of baseline kinesiophobia levels on the treatment outcomes of PNE combined with cognition-targeted exercises in people with CSP. This study was a secondary analysis of a multicenter, double-blind, randomized controlled trial. METHODS: Outcome measures included a numeric rating scale for pain (NRS), the Pain Disability Index (PDI), quality of life (Medical Outcomes Study 36-Item Health Survey [SF-36]), Pain Catastrophizing Scale (PCS), and Pain Vigilance and Awareness Questionnaire (PVAQ). Regression models were built using treatment (PNE plus cognition-targeted exercises or neck/back school plus general exercises), baseline scores on the Tampa Scale for Kinesiophobia (TSK), and time (in months) as independent variables. RESULTS: A significant 3-way interaction effect was found for the models of PDI, PCS, PVAQ, and the SF-36 mental domain, with estimates of -0.01, -0.01, -0.01, and 0.07, respectively. A significant effect of baseline TSK scores was found for the physical domain of the SF-36 (estimate = -3.16). For the NRS, no significant effect of baseline TSK scores was found. CONCLUSION: Our findings indicate that PNE plus cognition-targeted exercises can successfully decrease the unfavorable influence of pretreatment kinesiophobia on disability, mental health, pain catastrophizing, and hypervigilance over time in people with CSP. Nevertheless, higher scores in pretreatment kinesiophobia might still be a key factor for the lack of improvement in pain catastrophizing and hypervigilance following treatment. Regardless of the followed treatment program, pretreatment kinesiophobia was also shown to significantly influence physical health in people with CSP. IMPACT: This study provides novel insight into the unfavorable influence of kinesiophobia on treatment outcomes in people with CSP, and how PNE plus cognition-targeted exercises can limit this impact. Because this is one of the first studies to research possible predictors of this experimental treatment, its findings motivate further exploration of other possible influencing factors for treatment success of PNE plus cognition-targeted exercises. LAY SUMMARY: People with chronic spinal pain and high levels of fear of movement were found to have worse treatment outcomes compared to people with low levels of fear of movement. However, our experimental treatment, which includes pain neuroscience education combined with exercise therapy that reintroduces specific movements patients might fear, can decrease this negative influence of fear of movement in these patients.

Electroencephalography During Nociceptive Stimulation in Chronic Pain Patients: A Systematic Review.

BACKGROUND: With its high temporal resolution, electroencephalography (EEG), a technique that records electrical activity of cortical neuronal cells, is a potentially suitable technique to investigate human somatosensory processing. By using EEG, the processing of (nociceptive) stimuli can be investigated, along with the functionality of the nociceptive pathway. Therefore, it can be applied in chronic pain patients to objectify whether changes have occurred in nociceptive processing. Typically, so-called event-related potential (ERP) recordings are used, where EEG signals are recorded in response to specific stimuli and characterized by latency and amplitude. OBJECTIVE: To summarize whether differences in somatosensory processing occur between chronic pain patients and healthy controls, measured with ERPs, and determine whether this response is related to the subjective pain intensity. DESIGN: Systematic review. SETTING AND METHODS: PubMed, Web of Science, and Embase were consulted, and 18 case-control studies were finally included. SUBJECTS: The chronic pain patients suffered from tension-type headache, back pain, migraine, fibromyalgia, carpal tunnel syndrome, prostatitis, or complex regional pain syndrome. RESULTS: Chronic neuropathic pain patients showed increased latencies of the N2 and P2 components, along with a decreased amplitude of the N2-P2 complex, which was also obtained in FM patients with small fiber dysfunction. The latter also showed a decreased amplitude of the N2-P3 and N1-P1 complex. For the other chronic pain patients, the latencies and the amplitudes of the ERP components did not seem to differ from healthy controls. One paper indicated that the N2-P3 peak-to-peak amplitude correlates with the subjective experience of the stimulus. CONCLUSIONS: Differences in ERPs with healthy controls can mostly be found in chronic pain populations that suffer from neuropathic pain or where fiber dysfunction is present. In chronic pain populations with other etiological mechanisms, limited differences were found or agreed upon across studies.

Nutritional intervention in chronic pain: an innovative way of targeting central nervous system sensitization?

INTRODUCTION: Few treatment programs for chronic pain nowadays take a dietary pattern or adipose status into account. AREAS COVERED: An important role of neuroinflammation in chronic pain is now well established, at least in part due to increased central nervous system glial activation. Based on preclinical studies, it is postulated that the interaction between nutrition and central sensitization is mediated via bidirectional gut-brain interactions. This model of diet-induced neuroinflammation and consequent central sensitization generates a rationale for developing innovative treatments for patients with chronic pain. Methods: An umbrella approach to cover the authors' expert opinion within an evidence-based viewpoint. EXPERT OPINION: A low-saturated fat and low-added sugar dietary pattern potentially decreases oxidative stress, preventing Toll-like receptor activation and subsequent glial activation. A low-saturated fat and low-added sugar diet might also prevent afferent vagal nerve fibers sensing the pro-inflammatory mediators that come along with a high-(saturated) fat or energy-dense dietary pattern, thereby preventing them to signal peripheral inflammatory status to the brain. In addition, the gut microbiota produces polyamines, which hold the capacity to excite N-methyl-D-aspartate receptors, an essential component of the central nervous system sensitization. Hence, a diet reducing polyamine production by the gut microbiota requires exploration as a therapeutic target for cancer-related and non-cancer chronic pain.

Processing of Laser-Evoked Potentials in Patients with Chronic Whiplash-Associated Disorders, Chronic Fatigue Syndrome, and Healthy Controls: A Case-Control Study.

OBJECTIVE: Laser-evoked potentials (LEPs) are among the reliable neurophysiological tools to investigate patients with neuropathic pain, as they can provide an objective account of the functional status of thermo-nociceptive pathways. The goal of this study was to explore the functioning of the nociceptive afferent pathways by examining LEPs in patients with chronic whiplash-associated disorders (cWAD), patients with chronic fatigue syndrome (CFS), and healthy controls (HCs). DESIGN: Case-control study. SETTING: A single medical center in Belgium. SUBJECTS: The LEPs of 21 patients with cWAD, 19 patients with CFS, and 18 HCs were analyzed in this study. METHODS: All participants received brief nociceptive CO2 laser stimuli applied to the dorsum of the left hand and left foot while brain activity was recorded with a 32-channel electroencephalogram (EEG). LEP signals and transient power modulations were compared between patient groups and HCs. RESULTS: No between-group differences were found for stimulus intensity, which was supraliminal for Aδ fibers. The amplitudes and latencies of LEP wave components N1, N2, and P2 in patients with cWAD and CFS were statistically similar to those of HCs. There were no significant differences between the time-frequency maps of EEG oscillation amplitude between HCs and both patient populations. CONCLUSIONS: EEG responses of heat-sensitive Aδ fibers in patients with cWAD and CFS revealed no significant differences from the responses of HCs. These findings thus do not support a state of generalized central nervous system hyperexcitability in those patients.

Do Nutritional Factors Interact with Chronic Musculoskeletal Pain? A Systematic Review.

Dietary patterns may play an important role in musculoskeletal well-being. However, the link between dietary patterns, the components of patients' diet, and chronic musculoskeletal pain remains unclear. Therefore, the purpose of this review was to systematically review the literature on the link between dietary patterns, the components of patients' diet and chronic musculoskeletal pain. This review was conducted following the "Preferred Reporting Items for Systematic reviews and Meta-Analyses" (PRISMA) guidelines and was registered in PROSPERO with the registration number CRD42018110782. PubMed, Web of Science, and Embase online databases were searched. After screening titles and abstracts of 20,316 articles and full texts of 347 articles, 12 eligible articles were included in this review, consisting of nine experimental and three observational studies. Seven out of nine experimental studies reported a pain-relieving effect of dietary changes. Additionally, protein, fat, and sugar intake were found to be associated with pain intensity and pain threshold. In conclusion, plant-based diets might have pain relieving effects on chronic musculoskeletal pain. Patients with chronic rheumatoid arthritis pain can show inadequate intake of calcium, folate, zinc, magnesium, and vitamin B6, whilst patients with fibromyalgia can show a lower intake of carbohydrates, proteins, lipids, vitamin A-E-K, folate, selenium, and zinc. Chronic pain severity also shows a positive relation with fat and sugar intake in osteoarthritis, and pain threshold shows a positive association with protein intake in fibromyalgia.

The influence of nociceptive and neuropathic pain states on the processing of acute electrical nociceptive stimulation: A dynamic causal modeling study.

INTRODUCTION: Despite the worldwide increase in prevalence of chronic pain and the subsequent scientific interest, researchers studying the brain and brain mechanisms in pain patients have not yet clearly identified the exact underlying mechanisms. Quantifying the neuronal interactions in electrophysiological data could help us gain insight into the complexity of chronic pain. Therefore, the aim of this study is to examine how different underlying pain states affect the processing of nociceptive information. METHODS: Twenty healthy participants, 20 patients with non-neuropathic low back-related leg pain and 20 patients with neuropathic failed back surgery syndrome received nociceptive electrical stimulation at the right sural nerve with simultaneous electroencephalographic recordings. Dynamic Causal Modeling (DCM) was used to infer hidden neuronal states within a Bayesian framework. RESULTS: Pain intensity ratings and stimulus intensity of the nociceptive stimuli did not differ between groups. Compared to healthy participants, both patient groups had the same winning DCM model, with an additional forward and backward connection between the somatosensory cortex and right dorsolateral prefrontal cortex. DISCUSSION: The additional neuronal connection with the prefrontal cortex as seen in both pain patient groups could be a reflection of the higher attention towards pain in pain patients and might be explained by the higher levels of pain catastrophizing in these patients. CONCLUSION: In contrast to the similar pain intensity ratings of an acute nociceptive electrical stimulus between pain patients and healthy participants, the brain is processing these stimuli in a different way.

Chronic Musculoskeletal Pain and Nutrition: Where Are We and Where Are We Heading?

Nutrition is one of the most important lifestyle factors related to chronic diseases such as cancer, diabetes, and cardiovascular diseases. Additionally, poor diet is also considered a predicting, perpetuating, or underlying factor in chronic musculoskeletal pain. This narrative review provides an overview of current knowledge on the relationship between nutrition and chronic musculoskeletal pain (ie, inflammation, obesity, homeostatic balance, and central sensitization as underlying mechanisms). This review also identifies how dietary intake assessments and nutritional behavior interventions for chronic musculoskeletal pain can be used in clinical practice and identifies areas in need of additional research. Based on the available literature, dietary behavior and quality could have an impact on chronic musculoskeletal pain conditions, but the direction of this impact is unclear. There is a need for additional human nutrition studies that focus on specific musculoskeletal pain conditions and underlying pathologies.

Electrical (Pain) Thresholds and Conditioned Pain Modulation in Patients with Low Back-Related Leg Pain and Patients with Failed Back Surgery Syndrome: A Cross-Sectional Pilot Study.

OBJECTIVE: When evaluating sensory dysfunctions and pain mechanisms in patients with low back pain (LBP), a specific subgroup of patients with radicular symptoms is often excluded. Comparative studies that evaluate sensory sensitivity in patients with a dominant nociceptive and neuropathic pain component are rarely performed. Therefore, the goal of this study was to examine differences in electrical thresholds and conditioned pain modulation (CPM) between patients with low back-related leg pain (LBRLP) and patients with failed back surgery syndrome (FBSS). DESIGN: Cross-sectional study. SETTING: University Hospital Brussels. SUBJECTS: Twenty-one patients with LBRLP and 21 patients with FBSS were included. METHODS: Electrical detection thresholds (EDTs), electrical pain thresholds (EPTs), and CPM were evaluated on the symptomatic and nonsymptomatic sides. Within- and between-group differences were evaluated for all parameters. RESULTS: No between-group differences were found for EDT and EPT at both sides. On the nonsymptomatic side, a significantly lower CPM effect was found in the FBSS group (P = 0.04). The only significant within-group difference was an increased EDT at the symptomatic side in patients with FBSS (P = 0.01). CONCLUSIONS: LBP patients with a primary neuropathic pain component revealed altered detection sensitivity at the symptomatic side, without severe indications for altered nociceptive processing, compared with LBP patients without a dominant neuropathic pain component. Endogenous modulation is functioning in LBP patients, although it is possible that it might only be functioning partially in patients with a dominant neuropathic pain component.

Lifestyle and Chronic Pain across the Lifespan: An Inconvenient Truth?

Chronic pain has a tremendous personal and socioeconomic impact and remains difficult to treat. Therefore, it is important to provide an update on the current understanding regarding lifestyle factors in people with chronic pain across the lifespan. Lifestyle factors such as physical (in)activity, sedentary behavior, stress, poor sleep, unhealthy diet, and smoking are associated with chronic pain severity and sustainment. This applies to all age categories, that is, chronic pain across the lifespan. Yet current treatment options often do not or only partly address the many lifestyle factors associated with chronic pain or attempt to address them in a standard format rather than providing an individually tailored multimodal lifestyle intervention. The evidence regarding lifestyle factors is available in adults, but limited in children and older adults having chronic pain, providing important avenues for future research. In conclusion, it is proposed that treatment approaches for people with chronic pain should address all relevant lifestyle factors concomitantly in an individually-tailored multimodal intervention. Ultimately, this should lead to improved outcomes and decrease the psychological and socioeconomic burden of chronic pain. Level of Evidence: IV.

A Modern Pain Neuroscience Approach in Patients Undergoing Surgery for Lumbar Radiculopathy: A Clinical Perspective.

Around 20% of patients undergoing surgery for lumbar radiculopathy develop chronic pain after surgery, leading to high socioeconomic burden. Current perioperative interventions, including education and rehabilitation, are not always effective in preventing prolonged or chronic postoperative pain and disability. Here, a shift in educational intervention from a biomedical towards a biopsychosocial approach for people scheduled for lumbar surgery is proposed. Pain neuroscience education (PNE) is a biopsychosocial approach that aims to decrease the threat value of pain by reconceptualizing pain and increasing the patient's knowledge about pain. This paper provides a clinical perspective for the provision of perioperative PNE, specifically developed for patients undergoing surgery for lumbar radiculopathy. Besides the general goals of PNE, perioperative PNE aims to prepare the patient for postsurgical pain and how to cope with it.