Fibromyalgia Patients Research Articles

Prevalence and Characteristics of Fibromyalgia in Patients with Foot and Ankle Pain: The Experience of an Academic Podiatry Clinic

Background and Objectives: Research about the prevalence of fibromyalgia in podiatric patients is limited, with data suggesting potentially higher estimates and greater foot impairment in patients with fibromyalgia compared to healthy individuals. The aim of our study is to assess the prevalence of fibromyalgia in the podiatric healthcare setting and to research the characteristics of fibromyalgia patients with foot or ankle disorders. Materials and Methods: Consecutive patients visiting the academic podiatry clinic at the University of Bologna IRCCS Rizzoli Orthopaedic Institute between 11 January and 31 March 2021 were enrolled. Results: Of the 151 patients included, 21 met the fibromyalgia survey diagnostic criteria, accounting for a prevalence of 13.9% (95% CI 8.8-20.5). As part of the podiatric assessment, the Foot Function Index (FFI) was used to calculate the impact of foot and ankle problems. Moreover, patients with fibromyalgia were asked to complete the fibromyalgia impact questionnaire (FIQ). Fibromyalgia patients had significantly worse total FFI scores (63.4 ± 23.0% vs. 53.2 ± 20.3%, p = 0.038) and there was a significant linear correlation between the FFI and the FIQ (r = 0.72, p < 0.001). Conclusions: The prevalence of fibromyalgia in the academic podiatry clinic being 13.9% confirms that, in the healthcare setting, the disease can be more frequent than in the general population. Furthermore, our findings suggest a strong correlation between foot impairment and the impact of fibromyalgia.

Fibromiyaljili Hastalarda D Vitamin Düzeylerinin Değerlendirilmesi ve Fonksiyonel Durum ile İlişkisi

Aim: Fibromyalgia syndrome is a common musculoskeletal disorder, characterized by chronic&#x0D; widespread pain, multiple tender points, joint stiffness, and systemic symptoms without any underlying&#x0D; organic disease. The initial aim of the present study was to determine the vitamin D levels in patients&#x0D; with fibromyalgia and compare these values to those found in healthy subjects. Then, correlations&#x0D; between functional status, clinical severity of the disease, and vitamin D levels were assessed.&#x0D; Material and Methods: This case-control study included 137 female fibromyalgia patients and 109&#x0D; healthy female counterparts. The severity of pain was assessed by a visual analogue scale and the&#x0D; functional impact was evaluated through the Fibromyalgia Impact Questionnaire in the patient group.&#x0D; Vitamin D levels were compared between groups, and the correlation between vitamin D levels and&#x0D; questionnaire scores was determined.&#x0D; Results: Vitamin D and parathormone levels did not differ significantly between groups (p=0.858,&#x0D; p=0.790 respectively). The mean Fibromyalgia Impact Questionnaire scores and the medians for the&#x0D; visual analogue scale did not differ significantly among vitamin D deficient, insufficient, and sufficient&#x0D; patients (p=0.548 , p=0.952 respectively). In addition, no significant correlation between vitamin D&#x0D; levels and the Fibromyalgia Impact Questionnaire score was found(Spearman’s rho=0.056, p=0.513).&#x0D; Conclusion: This study did not show any significant differences between the vitamin D levels of&#x0D; fibromyalgia patients and those of healthy subjects. Further, in fibromyalgia patients, there was no&#x0D; correlation between vitamin D levels and functional status or disease severity

Effects of Walking as Physical Exercise on Functional Limitation through Pain in Patients with Fibromyalgia-How Does Catastrophic Thinking Contribute?

Background: Aerobic exercise has a beneficial impact on physical and mental health. However, patients with fibromyalgia do not always report perceiving these improvements. Objective: The aim of this study was to examine whether catastrophic thinking moderated the effects of perceived pain severity once an active and regular lifestyle had been established on functional limitation in chronic pain patients, in particular in fibromyalgia patients. Methods: The sample consisted of a total of 491 women with fibromyalgia diagnosed according to the criteria of the American College of Rheumatology. Participants completed an ad-hoc item about lifestyle related to walking pattern, the Brief Pain Inventory, the Pain Catastrophization Scale, and the Fibromyalgia Impact Questionnaire-Revised. To examine the relationship between the variables, a moderate mediation analysis was performed through the macro PROCESS (model 14). Results: The relationship between the performance of the recommended walking pattern and functional limitation was mediated by the severity of pain (B = −5.19, SE = 1.59, t = −3.25, 95% CI = [−4.06, −0.28], p < 0.001). Furthermore, it was found that the mediating effect of pain severity was moderated by catastrophic thinking (Index = −0.014, SE = 0.007, 95% CI [0.002, 0.030]). Conclusions: The positive effect of walking on functionality through the reduction of pain levels is favored when patients present low catastrophizing, which affects the relevance of including interventions focused on the reduction of catastrophizing in the prescription of physical exercise in patients with fibromyalgia as the treatment of choice.

Determining the PASS cut-off points for the FIQR, FASmod and PSD in patients with fibromyalgia: a registry-based study.

To determine the cut-off values of Patient Acceptable Symptom State (PASS) for the revised Fibromyalgia Impact Questionnaire (FIQR), the modified Fibromyalgia Assessment Scale (FASmod), and the Polysymptomatic Distress scale (PSD) and to determine the predictors of PASS in patients with fibromyalgia (FM). FM patients belonging to the Italian Fibromyalgia Registry (IFR) completed the FIQR, the FASmod and the PSD. The PASS was assessed using a dichotomous answer. The cut-off values were obtained through the receiver operating characteristic curve (ROC) analyses. A multivariate logistic regression analysis was performed to determine predictors of achieving the PASS. 5545 women (93.7%) and 369 males (6.3%) were included in the study. The 27.8% of patients reported an acceptable symptom state. Patients in PASS differed in all patient-reported outcome measures (p <0.001). The FIQR PASS threshold was ≤58 (area under the ROC curve [AUC] = 0.819). The FASmod PASS threshold was ≤23 (AUC = 0.805) and the PSD PASS threshold was ≤16 (AUC = 0.773). In the pairwise AUC comparison, the discriminatory power of the FIQR PASS outperforms both FASmod PASS (p = 0.0124) and PSD PASS (p <0.0001). Multivariate logistic analysis showed that FIQR items related to memory and pain were the only predictors of PASS. The FIQR, FASmod, and PSD PASS cut-off points for FM patients have never been determined before. This study provides additional information to facilitate interpretation of the severity assessment scales in daily practice and clinical research related to FM patients.

Effect of Psychodrama on Fibromyalgia Patients’ Pain Levels, Quality of Life, and Skills of Expressing Emotions

Effect of Psychodrama on Fibromyalgia Patients’ Pain Levels, Quality of Life, and Skills of Expressing Emotions

Blood transcriptome and machine learning identified the crosstalk between COVID-19 and fibromyalgia: a preliminary study.

The COVID-19 pandemic caused by SARS-CoV-2 has seriously threatened the human health. Growing evidence shows that COVID-19 patients who recovery will persist with symptoms of fibromyalgia (FM). However, the common molecular mechanism between COVID-19 and FM remains unclear. We obtained blood transcriptome data of COVID-19 (GSE177477) and FM (GSE67311) patients from GEO database, respectively. Subsequently, we applied Limma, GSEA, Wikipathway, KEGG, GO, and machine learning analysis to confirm the common pathogenesis between COVID-19 and FM, and screened key genes for the diagnosis of COVID-19 related FM. A total of 2505 differentially expressed genes (DEGs) were identified in the FM dataset. Functional enrichment analysis revealed that the occurrence of FM was intimately associated with viral infection. Moreover, WGCNA analysis identified 243 genes firmly associated with the pathological process of COVID-19. Subsequently, 50 common genes were screened between COVID-19 and FM, and functional enrichment analysis of these common genes primarily involved in immunerelated pathways. Among these common genes, 3 key genes were recognised by machine learning for the diagnosis of COVID-19 related FM. We also developed a diagnostic nomogram to predict the risk of FM occurrence which showed excellent predictive performance. Finally, we found that these 3 key genes were closely relevant to immune cells and screened potential drugs that interacted with the key genes. Our study revealed the bridge role of immune dysregulation between COVID-19 and fibromyalgia, and screened underlying biomarkers to provide new clues for further clinical research.

Psychological and attitudinal assessment of patients with Fibromyalgia undergoing antalgic management: a short report

Objectives: Fibromyalgia (FM) is a widespread condition that is difficult to manage medically. Often algologists are faced with patients who are poorly compliant with pharmacological treatment or with concomitant mood problems. There are treatments tailored to temperament and character patterns. In this study using the division into pain persistence and pain avoidance patterns, a stratification was hypothesized to facilitate its medical management using self-administered questionnaires. Methods: We screened the population consisting of FM patients to four different questionnaires, namely the Temperament and Character Inventory (TCI), Hospital Anxiety and Depression Scale, Short form 36 and the INTERMED- Self Assessment. Results: A total of thirty-two patients were enrolled. The analyzed population showed preponderant pain avoidance characteristics (90.7%). The persistence pattern proved to be present in only 9.3% of the population. The FM patients examined also reported an incidence of anxiety disorder of 71.9% and depressive disorder of 75%. Conclusion: Dividing the population with FM into patterns yielded uniform results. This justifies a multidisciplinary approach in these FM patients. The high incidence of anxiety and depression from the test results is an outcome that suggests the adoption of the HADS tool in the antalgic evaluation of FM patients.

Predicting Adherence to Walking from Anxiety, Depression, Disease Impact, Catastrophizing, and Cognitive Fusion in Patients with Fibromyalgia: Does Pain Severity Matter?

This study analyzed whether the contribution of several factors associated with walking adherence in fibromyalgia (FM) patients varies across pain severity levels. Participants were 228 women with FM (mean age 57 years; SD = 8.49). Bivariate analyses replicated the expected association between predictors (FM impact, anxiety, depression, catastrophizing, and cognitive fusion) and poorer adherence to walking. Multivariate analyses showed a negative contribution of FM impact, catastrophizing, and depression on walking adherence after controlling for pain levels (all p < 0.01). A moderation effect of pain severity in the relationship between predictors and adherence to walking was only found for cognitive fusion (B = -0.01, t = -2.02, p = 0.040). Specifically, cognitive fusion only contributed to poor walking adherence at moderate and severe pain levels, but not when pain was mild. The contribution of the remaining predictors was not moderated by pain levels, which means that they contributed to walking adherence irrespective of the pain severity of the patient. Pain severity did not contribute to walking adherence when controlling for the predictors. Clinical implications are discussed from the perspective of personalized interventions and preferable target interventions when attempting to increase adherence to walking in this population.

Efficiency of pain inhibition and facilitation of fibromyalgia patients is not different from healthy controls: Relevance of sensitivity-adjusted test stimuli.

Pain is a dynamic phenomenon dependent on the balance of endogenous excitatory and inhibitory systems, which can be characterized by quantitative sensory testing. Many previous studies of pain modulatory capacity of patients with fibromyalgia syndrome (FM) have reported decreased pain inhibition or increased pain facilitation. This is the first study to assess pain modulation, including conditioned pain modulation (CPM) and temporal pain summation, in the same healthy control (HC) and FM participants. Only sensitivity-adjusted stimuli were utilized for testing of conditioned pain modulation (CPM) and temporal pain summation in 23 FM patients and 28 HC. All subjects received sensitivity-adjusted ramp-hold (sRH) during testing of pain facilitation (temporal summation) and pain inhibition (CPM). CPM efficacy was evaluated with test stimuli applied either concurrently or after application of the conditioning stimulus. Finally, the effects of CPM on pressure pain thresholds were tested. FM subjects required significantly less intense test and conditioning stimuli than HC participants to achieve standardized pain ratings of 50 ± 10 numerical rating scale (NRS) (p = 0.03). Using such stimuli, FM subjects' temporal pain summation and CPM efficacy was not significantly different from HC (all p > 0.05), suggesting similar pain facilitation and inhibition. Furthermore, the CPM efficacy of FM and HC participants was similar regardless of whether the test stimuli were applied during or after the conditioning stimulus (p > 0.05). Similar to previous studies, FM participants demonstrated hyperalgesia to heat, cold, and mechanical stimuli. However, using only sensitivity-adjusted stimuli during CPM and temporal summation testing, FM patients demonstrated similarly effective pain inhibition and facilitation than HC, suggesting that their pain modulation is not abnormal.

Analysis of clinical and psychological characteristics in 250 patients with fibromyalgia

To analyze the clinical and psychological characteristics of fibromyalgia (FM), so as to further understand and improve the capability of identifying FM. The clinical data of 250 FM patients diagnosed in the outpatient clinic of the Department of Rheumatology, the First Medical Center, Chinese PLA General Hospital, from December 2019 to September 2021, were collected and analyzed. The patients aged 40 (31.0, 52.3) years, including 188 female patients (75.2%) and 62 male patients (24.8%). There was a statistically significant difference in age comparison between female [42.5 (33.0,54.0) years] and male patients [32.5 (27.8,43.5) years] (P<0.001). The score of pain degree was 6 (4, 8), and [7 (5, 8)] of female patients was higher than [6 (4, 7)] of the male patients (P=0.040). The widespread pain index (WPI) was 13 (10,15). The regions with high pain incidence were left shoulder girdle (87.2%, 218/250), right shoulder girdle (86.8%, 217/250), upper back (86.4%, 216/250), neck (79.6%, 199/250) and lower back (77.6%, 194/250) and etc. The incidence of chest pain in female patients (55.3%, 104/188) was lower than that in male patients (75.8%, 47/62) (P=0.004). The symptom severity scale (SSS) score was 8 (7-10). 74.6% (185/248) suffered from anxiety and 77.5% (193/249) suffered from depression in 249 patients. Female patients were more common in FM patients than male patients, the median age of female patients was older than that of male patients, and the median score of pain severity of female patients was higher than male patients. Shoulders girdle, upper back, neck and lower back were the most frequently reported pain regions, and the incidence of chest pain in female patients was lower than that in male patients. The incidence of major non-painful symptoms was high and the proportion with anxiety or depression was high. The above clinical features are very helpful for early diagnosis of FM.

Whole-Body Cryostimulation in Fibromyalgia

<h3>Research Objectives</h3> to determine whether the addition of Whole-Body Cryostimulation (WBC) to a rehabilitation program is able to induce a greater reduction of pain, depressive symptoms, disease impact and improvement in function and sleep quality in female patients with fibromyalgia (FM) as compared to matched controls undergoing only a rehabilitation program. <h3>Design</h3> Randomized controlled trial. <h3>Setting</h3> Participants were recruited consecutively from the in-patients of the Rehabilitation Unit in our hospital. <h3>Participants</h3> We selected 45 patients with: i) age between 18 and 65 years; ii) FM diagnosed by a rheumatologist according to American College of Rheumatology criteria; iii) FM diagnosed for more than one year. 25 patients were randomly allocated to the WBC group and 20 patients to the control group. <h3>Interventions</h3> Daily 45-min physiotherapy and 45-min standard supervised adapted physical activity sessions for an average length of hospital stay of 26 days. Patients allocated to the WBC group received additional ten 2-minute WBC sessions at a temperature of -110°. <h3>Main Outcome Measures</h3> Pain severity (VAS 0-10); Disease impact (Fibromyalgia Impact Questionnaire); Depressive symptomatology(BDI-II25); Sleep quality (VAS 0-10); 6-min walking test (meters) were measured before (T0) and after the completion of the rehabilitation program (T1). <h3>Results</h3> No significant differences between groups at T0 in terms of age, BMI, pain duration, number of pain medications, and scores on questionnaires were observed. Both groups reported positive changes in all outcomes at T1. The between-group comparison showed a statistically larger magnitude of changes in the WBC group at T1, specifically, in pain severity, disease impact, sleep quality, and depressive symptoms. Statistically significant improvements in 6MWT were observed at T1 in both groups. The between-group comparison at T1 did not show significant differences, but longer distances walked were evident in the WBC group. <h3>Conclusions</h3> Our preliminary results suggest that WBC could represent an effective add-on treatment for improving pain, disease impact, sleep quality, and depressive symptoms in FM patients. Larger studies are needed to confirm our results. <h3>Author(s) Disclosures</h3> Nothing to disclose.

Analysis of RNFL and GCL in patients with multiple sclerosis and fibromyalgia

AbstractPurpose: To evaluate the differences in RNFL and GCL between patients with relapsing–remitting multiple sclerosis (RR‐MS), fibromyalgia (FM) and healthy controls, as well as their correlation with disease time and severity.Methods: 94 eyes of RR‐MS patients, 55 eyes of FM patients and 90 eyes of healthy controls were evaluated using the Spectralis OCT Posterior Pole protocol (64‐cell array grid). The thicknesses of both layers were compared for each of the 64 cells between the three groups, the correlation of each layer with the time of the disease was studied, as well as with the EDSS in the case of RR‐MS and with the questionnaires FIQ and EQ‐5D in the case of FM.Results: We observed a significant thinning (p &lt; 0.05) of the GCL in both pathologies compared to healthy subjects, being the damage significantly greater in RR‐MS. Regarding the RNFL, a significant thinning was observed in the RR‐EM but not in the FM. On the other hand, GCL was correlated with the time of evolution in RR‐MS patients, but not in those with FM, and was significantly correlated with a greater impact of FM (FIQ and EQ‐5D), but not with the EDSS in the case of RR‐MS. In addition, it is in the GCL where a high concentration of cells (&gt;50%) which a greater ability to discriminate between healthy and pathological subjects (AUC &gt; 0.5) was found.Conclusions: The GCL damage in FM patients, similar to that in RR‐MS patients, suggests that there is an underlying neurodegenerative process in this pathology. In the absence of other biomarkers, OCT could be postulated as a potential biomarker in FM, since GCL shows significant thinning and correlates with the impact of this disease on quality of life.

Pulsed Laser Acupuncture in the Treatment of Pain and Heart Rate Variability in Fibromyalgia Patients: A Pilot Randomized Clinical Trial.

Introduction: Laser acupuncture (LA) is a medically approved treatment for chronic pain, especially fibromyalgia. It is widely known that all pain is related to autonomic modulation, which may influence heart rate variability (HRV). There are robust studies in the literature on the effect of LA with continuous frequency on musculoskeletal pain and autonomic modulation. However, little is known about the effect of pulsed frequency on fibromyalgia. Therefore, this study aimed to evaluate whether an individualized intervention protocol applying pulsed LA would provide benefits related to pain symptoms and cardiac autonomic modulation in patients with fibromyalgia. Methods: In this pilot randomized clinical controlled trial, the sample consisted of women with fibromyalgia between the ages of 40 and 80, randomized into two groups: a control group (CG; n=10) and an experimental group (EG; n=10). EG received the intervention twice per week for 3 weeks. Statistical analysis was conducted by delta (difference between post-intervention and pre-intervention) and the Shapiro-Wilk test (normality). For comparison between the groups, the Mann-Whitney test was used. Results: The results showed a significant reduction in pain intensity as reported via the pain numerical scale (PNS; P=0.00), generalized pain index (GPI; P=0.00), and symptom severity scale (SSS; P=0.00). There was no significant difference in any HRV variable (P>0.05). Conclusion: Pulsed LA, when applied in an individualized protocol, can reduce pain intensity, as reported on the PNS, GPI, and SSS. However, no therapeutic effect was observed for HRV.

Can Exercise Affect the Pain Characteristics in Patients with Fibromyalgia? A Randomized Controlled Trial.

Exercise is often recommended for fibromyalgia. The aim of this study was to investigate the possible influence and change in the pain characteristics of fibromyalgia patients when breathing exercises were added to their exercise program. A total of 106 patients were included and randomly divided into two groups. Τhe first group of patients followed a program of active exercises up to the limits of pain, lasting 30 min with a repetition of two times a week. Patients of the second group followed the same program with the addition of diaphragmatic breaths when they reached the pain limit. The patients completed three questionnaires: the Fibromyalgia Rapid Screening Tool (FiRST), the Brief Pain Inventory (BPI), and the Pain Quality Assessment Scale (PQAS)-once at the beginning, once again after three weeks of exercise, and again 3 months since the beginning of the program. Independent t-tests for the mean total change scores in pain scales demonstrated that for the second group there was a greater improvement in all pain scales, except for the PQAS Deep Pain subscale (p = 0.38). In conclusion, both groups showed significant improvement in all characteristics of the pain scales; however, the improvement of the second group was significantly higher.

Fibromyalgia Pathophysiology.

This article examines the biological, genetic, and environmental aspects of fibromyalgia that may have an impact on its pathogenesis. Symptoms of fibromyalgia may be related to aberrations in the endogenous inhibition of pain as well as changes in the central processing of sensory input. Genetic research has revealed familial aggregation of fibromyalgia and other related disorders like major depressive disorder. Dysfunctional pain processing may also be influenced by exposure to physical or psychological stressors, abnormal biologic reactions in the autonomic nervous system, and neuroendocrine responses. With more research the pathophysiology of fibromyalgia will be better understood, leading to more logical and focused treatment options for fibromyalgia patients.

Identification of Resting-State Network Functional Connectivity and Brain Structural Signatures in Fibromyalgia Using a Machine Learning Approach.

Abnormal resting-state functional connectivity (rs-FC) and brain structure have emerged as pathological hallmarks of fibromyalgia (FM). This study investigated and compared the accuracy of network rs-FC and brain structural features in identifying FM with a machine learning (ML) approach. Twenty-six FM patients and thirty healthy controls were recruited. Clinical presentation was measured by questionnaires. After MRI acquisitions, network rs-FC z-score and network-based gray matter volume matrices were exacted and preprocessed. The performance of feature selection and classification methods was measured. Correlation analyses between predictive features in final models and clinical data were performed. The combination of the recursive feature elimination (RFE) selection method and support vector machine (rs-FC data) or logistic regression (structural data), after permutation importance feature selection, showed high performance in distinguishing FM patients from pain-free controls, in which the rs-FC ML model outperformed the structural ML model (accuracy: 0.91 vs. 0.86, AUC: 0.93 vs. 0.88). The combined rs-FC and structural ML model showed the best performance (accuracy: 0.95, AUC: 0.95). Additionally, several rs-FC features in the final ML model correlated with FM's clinical data. In conclusion, ML models based on rs-FC and brain structural MRI features could effectively differentiate FM patients from pain-free subjects.

Fibromyalgia and nonfibromyalgia chronic pain: Differences in psychological characteristics and treatment outcomes.

The aim of this study was to explore differential psychological profiles among patients with chronic pain with and without fibromyalgia, and to determine the results of the cognitive behavioral therapy (CBT) for pain. Thirty patients with chronic pain and 60 patients with fibromyalgia were referred to 10 weekly sessions of CBT in a general hospital and were evaluated in pain-related variables, psychopathological symptoms, coping strategies, resilience, and quality of life. The program was implemented in specific groups for patients with fibromyalgia and nonfibromyalgia chronic pain. After the intervention, patients with fibromyalgia showed higher levels of psychopathology, rated their health status as poorer, and presented larger amplification of symptoms, higher levels of somatization, a more ruminating style of thinking and greater distress. Patients without fibromyalgia achieved better therapeutic results in both pain intensity (d=0.39 vs. d=0.12) and psychopathological distress (d=0.77 vs. d=0.11) compared to patients with fibromyalgia. Therefore, differential profiles and limited therapeutic results in fibromyalgia patients suggest the need to outline differentiated treatments and include other therapeutic strategies.

Effect of Single Session of Anodal M1 Transcranial Direct Current Stimulation-TDCS-On Cortical Hemodynamic Activity: A Pilot Study in Fibromyalgia.

Transcranial direct current stimulation (TDCS) on the primary motor cortex (M1) has been reported to be effective in fibromyalgia (FM). Our previous works have shown hypometabolism of motor networks in FM using Functional Near Infrared Spectroscopy (fNIRS), which could contribute to pain symptoms. To investigate if a single Transcranial Direct Current Stimulation (TDCS) session can restore the reduced metabolism expected in FM patients, we compared metabolic activity in FM patients and controls during a finger-tapping task in basal condition, sham condition, and under anodal TDCS on M1. During the finger tapping task, a continuous wave 20 channel fNIRS system was placed across the bilateral central-frontal areas in 22 healthy controls and 54 FM patients. Subjects were randomly assigned to real TDCS or sham stimulation. The finger-tapping slowness did not change after real and sham stimulation. After real TDCS stimulation, FM patients showed an increased activation of cortical motor regions (t-statistic = -2.5246, p-value = 0.0125 for the stimulated hemisphere and t-statistic = -4.6638, p-value = 0.0001 for the non-stimulated hemisphere). The basal differences between FM and controls reverted after real TDCS, while this effect was not observed for sham stimulation. A single TDCS session of the cortical motor network seemed able to restore basic cortical hypometabolism in FM patients. Further studies could clarify the long-term effect of M1 stimulation on cortical metabolism, and its relevance in pain processing and clinical features.

Spinal dopaminergic D1 and D5 receptors contribute to reserpine-induced fibromyalgia-like pain in rats

Fibromyalgia is a complex pain syndrome without a precise etiology. Reduced monoamines levels in serum and cerebrospinal fluid in fibromyalgia patients has been reported and could lead to a dysfunction of descending pain modulatory system producing the painful syndrome. This study evaluated the role of D1-like dopamine receptors in the reserpine-induced fibromyalgia-like pain model in female Wistar rats. Reserpine-treated animals were intrathecally injected with different dopamine receptors agonists and antagonists, and small interfering RNAs (siRNAs) against D1 and D5 receptor subtypes. Withdrawal and muscle pressure thresholds were assessed with von Frey filaments and the Randall-Selitto test, respectively. Expression of D1-like receptors in lumbar spinal cord and dorsal root ganglion was determined using real time polymerase chain reaction (qPCR). Reserpine induced tactile allodynia and muscle hyperalgesia. Intrathecal dopamine and D1-like receptor agonist SKF-38393 induced nociceptive hypersensitivity in naïve rats, whilst this effect was prevented by the D1-like receptor antagonist SCH-23390. Moreover, SCH-23390 induced a sex-dependent antiallodynic effect in reserpine-treated rats. Furthermore, transient silencing of D1 and D5 receptors significantly reduced reserpine-induced hypersensitivity in female rats. Reserpine slightly increased mRNA D5 receptor expression in dorsal spinal cord, but not in DRG. This work provides new insights about the involvement of the spinal dopaminergic D1/D5 receptors in reserpine-induced hypersensitivity in rats.

Relations between short-term memory and the within-subject variability of experimental pain intensity reports: Results from healthy and Fibromyalgia patients.

While factors contributing to between-subjects differences in pain have been studied extensively, factors contributing to the within-subjects variability of pain reports are yet unexplored. The aim of this investigation was to assess possible associations between short-term memory and the within-subjects variability of pain reports in healthy and chronic pain patients. Healthy participants were recruited at the University of Haifa, Israel, and Fibromyalgia patients were recruited at a rheumatology department in a central hospital in Lisbon, Portugal. Following consent, both cohorts underwent the same procedures, including the digit-span test, assessing short-term memory, and the FAST procedure, assessing within-subject variability of pain intensity reports in response to experimental pain. One-hundred twenty-one healthy volunteers and 29 Fibromyalgia patients completed the study. While a significant correlation was found between the within-subjects variability and the total score of the short-term memory task (Spearman's r = 0.394, P = 0.046) in the Fibromyalgia group, a marginal correlation emerged in the healthy cohort (r = 0.174, P = 0.056). A possible interpretation of these results is that in the patients' group, at least some of the within-subjects variability of pain intensity reports might be due to error measurement derived by poorer short-term memory, rather than true fluctuations in perception.