Mechanisms of chronic pain in inflammatory rheumatism: the role of descending modulation.

ABSTRACT: Persistent pain despite satisfactory disease treatment is frequent in rheumatoid arthritis (RA) and spondyloarthritis (Spa) and may result from specific changes in central pain processing. We assessed these mechanisms further by systematically comparing thermal pain thresholds and conditioned pain modulation (CPM) between patients with active RA or Spa and healthy controls. We included 50 patients with RA and 50 patients with Spa and 100 age-matched and sex-matched controls. Heat and cold pain thresholds (HPT-CPT) were measured on the dominant forearm, and CPM was assessed by applying conditioning stimuli (immersion in a cold-water bath) to one foot and the nondominant hand in 2 successive randomized sequences. Descending pain modulation was assessed as the difference in HPTs (in °C) before and after conditioning. Larger HPT differences (ie, a larger CPM effect) reflected more efficient descending inhibition. Potential associations between changes in CPM and clinical data, including disease activity, pain intensity, and psychological and functional variables, were systematically assessed. Heat pain threshold and cold pain threshold were similar in patients and controls. The mean CPM effect was significantly weaker in patients than that in controls for conditioning applied to either the foot (0.25°C ±2.57 vs 2.79°C ±2.31; P < 0.001) or the nondominant hand (0.57°C ±2.74 vs 2.68°C ±2.12; P < 0.001). The smaller CPM effect in patients was correlated with average pain intensity, but not with disease activity or other clinical characteristics, suggesting a significant pathophysiological role for changes in endogenous pain modulation in the mechanisms of chronic pain associated with inflammatory rheumatism.

Patient Reported Outcome Measures in Chronic Neuropathic Pain Clinical Trials - A Systematic Literature Review.

In neuropathic pain clinical trials, the patient's perspective is often insufficiently reflected focusing mainly on pain intensity. Comparability of outcome assessment is limited due to heterogenous patient reported outcome measures (PROMs). The MEDLINE, CENTRAL, and Embase databases and reference lists of published meta-analyses were searched. Randomized controlled studies assessing treatment efficacy of drugs for chronic neuropathic pain were included. PROMs were assigned to recommended IMMPACT/NeuPSIG domains: pain intensity, pain other aspects, physical functioning, emotional functioning, global improvement and satisfaction, adverse events, participant disposition. Domains and PROMs were compared regarding the publication year and methodological quality of the studies. Within the 251 included studies 200 PROMs were used with 27 being recommended by IMMPACT/NeuPSIG. The number of domains was higher in high/moderate quality studies. The (sub-) domains 'physical functioning', 'global improvement and satisfaction', and 'neuropathic pain quality' were assessed more frequently in high/moderate quality studies and those published after 2011. Recent studies and those of better quality more often used the recommended PROMs. Although neuropathic assessment via PROMs has improved, there is still a high heterogeneity. A standardized core set of outcome domains and should be defined to improve neuropathic pain treatment and to achieve better comparability of clinical trials. Perspective: This systematic literature review assesses the use of patient reported outcome measures (PROMs) in chronic neuropathic pain. The results show that there is still a high heterogeneity, highlighting the need for a standardized core set of outcome domains and PROMs to improve comparability of clinical trials and neuropathic pain treatment.

"FastSchool": A single session of an interprofessional pain management program for chronic pain patients inspired by cognitive behavioral therapy.

OBJECTIVES: Multidisciplinary approaches to treating chronic pain have been proven effective. Currently, chronic pain patients face lengthy waitlists in pain medicine departments. To overcome this problem, we developed the "FastSchool" program to educate patients about pain management and treatment. In this study, we evaluated the benefit of a "FastSchool" session on pain and catastrophizing in chronic pain patients. METHODS: Included patients had chronic non-cancer pain, no more than 2 visits to a pain medicine department. Patients attended a single 3-hour session, conducted by an interprofessional team. Four topics were addressed: chronic pain mechanisms, pharmacological therapies, physical activity, and the management of analgesics. Patients completed questionnaires at baseline and at 3 months post-session to assess pain interference, pain intensity, and catastrophizing. RESULTS: The study population included 88 patients; 71 completed the follow-up questionnaires. Pain interference (p = 0.002), average pain intensity (p = 0.013), and catastrophizing (p < 0.001) decreased 3 months after FastSchool. At M3, 35 % of patients felt their pain had improved based on the Patient Global Impression of Change. CONCLUSION: FastSchool, an innovative short-term educational program inspired by cognitive behavioral therapy, showed positive results in reducing pain impact. PRACTICE IMPLICATIONS: Implementation of FastSchool in pain medicine departments would reduce waitlist times for non-pharmacological treatment.

Osteopathic medicine for fibromyalgia: a sham-controlled randomized clinical trial.

BACKGROUND: Patients with fibromyalgia (FM) frequently resort to osteopathic or chiropractic treatment, despite very weak supporting evidence. We aimed to assess the efficacy of osteopathic manipulation in FM in a properly controlled and powered randomized clinical trial. METHODS: Patients were randomized to osteopathic or sham treatment. Treatment was administered by experienced physical medicine physicians, and consisted of six sessions per patient, over 6 weeks. Treatment credibility and expectancy were repeatedly evaluated. Patients completed standardized questionnaires at baseline, during treatment, and at 6, 12, 24, and 52 weeks after randomization. The primary outcome was pain intensity (100-mm visual analog scale) during the treatment period. Secondary outcomes included fatigue, functioning, and health-related quality of life. We performed primarily intention-to-treat analyses adjusted for credibility, using multiple imputation for missing data. RESULTS: In total, 101 patients (94% women) were included. Osteopathic treatment did not significantly decrease pain relative to sham treatment (mean difference during treatment: -2.2 mm; 95% confidence interval, -9.1 to 4.6 mm). No significant differences were observed for secondary outcomes. No serious adverse events were observed, despite a likely rebound in pain and altered functioning at week 12 in patients treated by osteopathy. Patient expectancy was predictive of pain during treatment, with a decrease of 12.9 mm (4.4-21.5 mm) per 10 points on the 0-30 scale. Treatment credibility and expectancy were also predictive of several secondary outcomes. CONCLUSION: Osteopathy conferred no benefit over sham treatment for pain, fatigue, functioning, and quality of life in patients with FM. These findings do not support the use of osteopathy to treat these patients. More attention should be paid to the expectancy of patients in FM management.

Quality of life and impact of pain in women treated with aromatase inhibitors for breast cancer. A multicenter cohort study.

Women with hormone-dependent breast cancer are treated with aromatase inhibitors (AI) to slow disease progression by decreasing estrogen levels. However, AI have adverse effects, including pain, with potentially serious impact on quality of life (QOL) and treatment compliance. We evaluated quality of life during the first year of AI treatment, focusing particularly on the impact of pain. In a multicenter cohort study of 135 women with early-stage breast cancer, free of pain at the initiation of AI treatment, quality of life (by the EORTC QLQ-BR23), somatic and psychic symptoms, psychological characters, temperament and coping strategies were assessed at baseline and at each follow-up visit (1, 3, 6 and 12 months). The impact of treatment-induced pain on quality of life during follow-up was determined with repeated-measures regression models. These models were constructed to assess the effects of pain and pain type on quality of life during follow-up, taking into account predictors associated with quality of life at baseline. Prior ganglion resection, taxane treatment and chemotherapy, a high amplification score on the pain catastrophizing scale, and a high harm avoidance score on the personality questionnaire were associated with a significantly lower baseline QOL. Fifty-seven percent of women developed pain of five different types: upper or lower limb joint pain, diffuse pain, neuropathic pain, tendon pain and mixed pain. A significant decrease in QOL was noted in the women with pain, particularly for body image, sexual functioning and future perspectives. Moreover, the impact of pain on QOL depended on the type of pain experienced. In conclusion, women treated with aromatase inhibitors display changes in quality of life and the degree of change in quality of life depends mostly on the type of pain experienced. Oncologists and patients should be aware of painful adverse effects of AI and encouraged to provide or receive earlier and more appropriate management of these effects.

Napping reverses increased pain sensitivity due to sleep restriction.

STUDY OBJECTIVE: To investigate pain sensitivity after sleep restriction and the restorative effect of napping. DESIGN: A strictly controlled randomized crossover study with continuous polysomnography monitoring was performed. SETTING: Laboratory-based study. PARTICIPANTS: 11 healthy male volunteers. INTERVENTIONS: Volunteers attended two three-day sessions: "sleep restriction" alone and "sleep restriction and nap". Each session involved a baseline night of normal sleep, a night of sleep deprivation and a night of free recovery sleep. Participants were allowed to sleep only from 02:00 to 04:00 during the sleep deprivation night. During the "sleep restriction and nap" session, volunteers took two 30-minute naps, one in the morning and one in the afternoon. MEASUREMENTS AND RESULTS: Quantitative sensory testing was performed with heat, cold and pressure, at 10:00 and 16:00, on three areas: the supraspinatus, lower back and thigh. After sleep restriction, quantitative sensory testing revealed differential changes in pain stimuli thresholds, but not in thermal threshold detection: lower back heat pain threshold decreased, pressure pain threshold increased in the supraspinatus area and no change was observed for the thigh. Napping restored responses to heat pain stimuli in the lower back and to pressure stimuli in the supraspinatus area. CONCLUSIONS: Sleep restriction induces different types of hypersensitivity to pain stimuli in different body areas, consistent with multilevel mechanisms, these changes being reversed by napping. The napping restorative effect on pain thresholds result principally from effects on pain mechanisms, since it was independent of vigilance status.

Classification of and risk factors for estrogen deprivation pain syndromes related to aromatase inhibitor treatments in women with breast cancer: a prospective multicenter cohort study.

UNLABELLED: Aromatase inhibitors (AIs) are the first-line treatment in women with breast cancer for total estrogen depletion. Half the treated women may develop pain, and this condition may therefore be seen as a clinical model of pain related to estrogen deprivation. In this prospective multicenter study, we classified AI-related pain syndromes and identified their predictors. A 1-year, prospective, multicenter cohort study, with 6 visits, was carried out on 135 women with early-stage breast cancer and no pain at the start of AI treatment. At initial assessment, we investigated clinical (demographic and psychosocial, cancer characteristics and treatment, sleep, quality of life), biological (sex hormones, vitamin D, bone biomarkers, oxidative stress, immunologic and inflammatory markers), environmental, and genetic (polymorphism for pain mechanisms) risk factors for pain. During 1 year of follow-up, 77 women (57%) developed pain, leading to AI discontinuation in 12 cases. Five pain syndromes were identified: joint pain (36%), diffuse pain (22%), tendinitis (22%), neuropathic pain (9%), and mixed pain (11%), which are mostly persistent (57%), with diffuse and joint pains the most intense. Risk factors for the development of pain included higher levels of anxiety and impaired quality of life at the initial assessment, whereas cancer characteristics, genetic background, inflammation, and immunologic and hormonal status at baseline were not significant predictors. PERSPECTIVE: This article presents a classification of AI-related pain syndromes induced by estrogen deprivation that were previously described as arthralgia, but not as neuropathic, diffuse, and mixed pain. This estrogen deprivation-related condition represents a clinical model of pain, and our study identified mostly psychological risk factors for pain development.

The double nucleation model for sickle cell haemoglobin polymerization: full integration and comparison with experimental data.

Sickle cell haemoglobin (HbS) polymerization reduces erythrocyte deformability, causing deleterous vaso-occlusions. The double-nucleation model states that polymers grow from HbS aggregates, the nuclei, (i) in solution (homogeneous nucleation), (ii) onto existing polymers (heterogeneous nucleation). When linearized at initial HbS concentration, this model predicts early polymerization and its characteristic delay-time (Ferrone et al. J Mol Biol 183(4):591-610, 611-631, 1985). Addressing its relevance for describing complete polymerization, we constructed the full, non-linearized model (Simulink), The MathWorks). Here, we compare the simulated outputs to experimental progress curves (n = 6-8 different [HbS], 3-6 mM range, from Ferrone's group). Within 10% from start, average root mean square (rms) deviation between simulated and experimental curves is 0.04 +/- 0.01 (25 degrees C, n = 8; mean +/- standard error). Conversely, for complete progress curves, averaged rms is 0.48 +/- 0.04. This figure is improved to 0.13 +/- 0.01 by adjusting heterogeneous pathway parameters (p < 0.01): the nucleus stability (sigma(2) micro( cc ): + 40%), and the fraction of polymer surface available for nucleation (phi), from 5e(-7), (3 mM) to 13 (6 mM). Similar results are obtained at 37 degrees C. We conclude that the physico-chemical description of heterogeneous nucleation warrants refinements in order to capture the whole HbS polymerization process.