Biology and therapy of fibromyalgia. Genetic aspects of fibromyalgia syndrome

Effectiveness of balneotherapy in reducing pain, disability, and depression in patients with Fibromyalgia syndrome: a systematic review with meta-analysis

Balneotherapy, using heated natural mineral waters at 36-38 °C, presents a comprehensive treatment approach for Fibromyalgia Syndrome (FMS). This study aims to assess the effect of balneotherapy in reducing pain intensity, disability, and depression in patients with FMS. We want to assess this effect at just four time-points: immediately at the end of the therapy, and at 1, 3, and 6 months of follow-up. Following PRISMA guidelines, we conducted an aggregate data meta-analysis, registered in PROSPERO CRD42023478206, searching PubMed Medline, Science Direct, CINAHL Complete, Scopus, and Web of Science until August 2023 for relevant randomized controlled trials (RCTs) that assess the effect of balneotherapy on pain intensity, disability, and depression in FMS patients. Methodological quality was assessed using the Cochrane methodology, and the pooled effect was calculated using Cohen's standardized mean difference (SMD) and its 95% confidence interval (95% CI) in a random-effects model. Sixteen RCTs were included in the meta-analysis. Balneotherapy is effective in reducing pain intensity (SMD - 1.67; 95% CI -2.18 to -1.16), disability (SMD - 1.1; 95% CI -1.46 to -0.7), and depression (SMD - 0.51; 95% CI -0.93 to -0.9) at the end of the intervention. This effect was maintained at 1, 3, and 6 months for pain intensity and disability. Balneotherapy improves both pain intensity and disability in patients with FMS, providing evidence that its positive effects are sustained for up to 6 months of follow-up. Nevertheless, it is important to note that the improvement in depression varies across different temporal phases.

Frequency of idiopathic intracranial hypertension with ultrasound in patients with fibromyalgia: Relation with function, central sensitization, and neuropathic pain

OBJECTIVE

The purpose of this study was to evaluate the prevalence of idiopathic intracranial hypertension (IIH) in fibromyalgia (FMS) patients by utilizing ultrasound to measure the optic nerve sheath diameter (ONSD), a marker of elevated intracranial pressure and also to investigate the relationship with function, fatigue, quality of life (QOL), central sensitization (CS) and neuropathic pain.

METHODS

The study encompassed 80 female FMS patients and 75 healthy controls. Ultrasound was employed to measure the average ONSD in both groups. Conditions potentially elevating intracranial pressure were ruled out following neurological assessments. Pain (via visual analog scale, VAS), function (revised Fibromyalgia Impact Questionnaire, r-FIQ), QOL (Short Form-36, SF-36), fatigue (fatigue severity scale, FACIT), CS (Central Sensitization Scale), and neuropathic pain (Douleur Neuropathique-4) were evaluated.

RESULTS

The average ONSD was significantly higher in the patient group than the control group. Patients with ONSD >5.5 mm consistent with IIH were categorized as Group 1 (n = 54, 67.5%), while those with a diameter of 5.5 mm and below-formed Group 2. VAS pain (p = .033) and FIQ-R scores (p = .033) were significantly higher in Group 1 than Group 2. Headache was found more common in Group 1.

CONCLUSION

This study unveils a substantial occurrence (67.5%) of IIH in FMS patients, suggesting shared pathophysiological mechanisms contributing to symptoms like fatigue, headache, and cognitive dysfunction. Additionally, these findings implicate heightened functional impairment, CS, headache, and fatigue in FMS patients with IIH.

Neurophysiological and Psychosocial Mechanisms of Fibromyalgia: A Comprehensive Review and Call for An Integrative Model

Research into the neurobiological and psychosocial mechanisms involved in fibromyalgia has progressed remarkably in recent years. Despite this, current accounts of fibromyalgia fail to capture the complex, dynamic, and mutual crosstalk between neurophysiological and psychosocial domains. We conducted a comprehensive review of the existing literature in order to: a) synthesize current knowledge on fibromyalgia; b) explore and highlight multi-level links and pathways between different systems; and c) build bridges connecting disparate perspectives. An extensive panel of international experts in neurophysiological and psychosocial aspects of fibromyalgia discussed the collected evidence and progressively refined and conceptualized its interpretation. This work constitutes an essential step towards the development of a model capable of integrating the main factors implicated in fibromyalgia into a single, unified construct which appears indispensable to foster the understanding, assessment, and intervention for fibromyalgia.

Psychoeducation for Fibromyalgia Syndrome: A Systematic Review of Emotional, Clinical and Functional Related-Outcomes

Fibromyalgia Syndrome (FMS) is a chronic condition of widespread pain accompanied by several symptoms such as stiffness, fatigue, sleep problems, depression, anxiety, and cognitive deficits. To date, there is no specific treatment for FMS. The European League Against Rheumatism, and the majority of the international recommendations for managing FMS, has claimed psychoeducational intervention as the first step in FMS treatment for adequate symptoms management. However, scientific studies in this regard are scarce, diverse, and with contradictory findings. Results integration from analogous studies could provide a clear presentation of the real clinical value of psychoeducation in FMS. Therefore, the current systematic review aims at exploring the effect of psychoeducation on emotional, clinical, and functional symptoms of FMS patients and encourages researchers towards psychoeducation's procedure optimization and systematization. The systematic review was conducted according to the guidelines of the Cochrane Collaboration and PRISMA statements. The selected articles were evaluated using the Cochrane risk of bias (ROB) assessment tool. The selected articles were extracted from PubMed, Scopus, and Web of Science databases. The literature search identified 11 studies eligible for the systematic review. The ROB evaluation revealed that 2 of the 11 studies showed a low quality, the other 2 had a moderate quality, and the remaining 7 studies exhibited a high quality. Results showed that psychoeducation is generally included as an important first therapeutic step in multicomponent treatments for FMS. Moreover, psychoeducation generally seems to be quite beneficial in reducing emotional (i.e., number of days feeling emotionally well, general anxiety, depression levels, etc.) and clinical symptoms (levels of fatigue, morning stiffness, pain intensity, etc.), as well as increasing functional status (i.e., general physical function, morning fatigue, stiffness, etc.). Despite that psychoeducation´s clinical benefits are highlighted, there is scarce amount of research on psychoeducation beyond its usefulness as part of multicomponent treatments.

Prevalence of Fibromyalgia Syndrome in Active-Duty Military Personnel

OBJECTIVE

Previous research with civilian populations has found strong associations between fibromyalgia (FM) and posttraumatic stress disorder (PTSD). We undertook this study to investigate the prevalence of FM in military service members with and without PTSD.

METHODS

Participants were active duty military personnel recruited into either an epidemiologic cohort study of service members before a military deployment or 1 of 3 PTSD treatment trials. Instruments used to document FM and PTSD included the PTSD Checklist-Stressor-Specific Version, the PTSD Symptom Scale-Interview, and the 2012 American College of Rheumatology FM questionnaire.

RESULTS

Across the 4 studies, 4,376 subjects completed surveys. The prevalence of FM was 2.9% in the predeployment cohort, and the prevalence was significantly higher in individuals with PTSD (10.8%) compared with those without PTSD (0.8%). In the treatment trials, all of the participants met criteria for PTSD before starting treatment, and the prevalence of FM was 39.7%.

CONCLUSION

The prevalence of FM in active duty service members preparing to deploy is similar to that reported for the general population of the US but is higher than expected for a predominantly male cohort. Furthermore, the prevalence of FM was significantly higher in service members with comorbid PTSD and was highest among those seeking treatment for PTSD. Further investigation is needed to determine the factors linking PTSD and FM.

Relationship Between Vitamin D Receptor Gene BsmI Polymorphism and Fibromyalgia Syndrome

Purpose

Vitamin D receptor (VDR) has been proposed as a possible marker for fibromyalgia syndrome (FMS). The purpose of this study is to characterize the expression pattern of BsmI polymorphism (rs1544410) in the VDR gene in women with FMS and the genotype-phenotype association.

Methods

A total of 105 FMS patients and 105 controls were included in this study. VDR gene BsmI polymorphism was assessed by polymerase chain reaction (PCR) and restriction fragment length polymerase (RFLP) method.

Results

There was no significant difference in the frequency distribution of both genotypes and alleles for VDR gene BsmI polymorphism between FMS patients and controls (p>0.05). The frequencies of BB, Bb, and bb in the VDR gene BsmI polymorphism were 19%, 43%, and 37% in patients, while in controls were 22.9%, 55.2%, and 21.9%. However, we did not find any significant association between the clinical symptoms of this disease and VDR BsmI genotypes among FMS patients (p>0.05).

Conclusions

The relationship between the VDR gene BsmI polymorphism and FMS could not be determined in this study. However, further studies with a larger sample size may be required to show a relation between the VDR gene BsmI polymorphism and FMS.

Effectiveness of Pain Neuroscience Education in Patients with Fibromyalgia: A Systematic Review and Meta-Analysis

PURPOSE

To assess the effects of pain neuroscience education (PNE) on patients with fibromyalgia (FM) in terms of pain intensity, fibromyalgia impact, anxiety, and pain catastrophizing.

METHODS

A systematic review and meta-analysis of randomized controlled trials was conducted. Standardized mean differences (SMDs) and 95% confidence intervals (CIs) were calculated with RStudio software for relevant outcomes and were pooled in a meta-analysis using the random effects model.

RESULTS

A total of 8 studies were included. The meta-analysis showed statistically significant differences in the pain intensity with a moderate clinical effect in 7 studies in the post-intervention assessment (SMD:-0.76; 95% CI:-1.33- -0.19; p < 0.05) with evidence of significant heterogeneity (p < 0.05, I2=92%) but not in fibromyalgia impact, anxiety, and pain catastrophizing (p > 0.05). Regarding the follow-up assessment, only the fibromyalgia impact showed significant improvements with a very small clinical effect in 9 studies (SMD:-0.44; 95% CI:-0.73- -0.14; p < 0.05) with evidence of significant heterogeneity (p < 0.05, I2 = 80%). Applying a sensitivity analysis with the PNE face-to-face interventions, the meta-analysis showed a significant decrease of pain intensity with a moderate clinical effect at post-intervention and follow-up without evidence of significant heterogeneity (p < 0.05, I2=10%).

CONCLUSIONS

There is low quality evidence that in patients with FM, PNE can decrease the pain intensity post-intervention and also the fibromyalgia impact in the follow-up. However, it appears that PNE showed no effect on anxiety and pain catastrophizing.

UNRAVELING THE CLINICO-GENETIC ASSOCIATION OF CATECHOL-O-METHYLTRANSFERASE-RS4680 G>A GENE POLYMORPHISM IN WOMEN WITH FIBROMYALGIA SYNDROME

OBJECTIVE

The aim: To determine the clinical and the genetic association of the COMT rs4680 SNP in women with FMS.

PATIENTS AND METHODS

Materials and methods: Extracted DNA from peripheral blood samples were utilized as template for the PCR and RFLP analysis.

RESULTS

Results: A significant difference was found in the distribution of the COMT genotype between FMS patients and controls (P<0.05). The frequency of GG, AG, AA genotypes were 12%, 72%, 21% in FMS patients and 32%, 62%, 11% in controls. The clinical features of FMS reveal that FIQR and the severity of pain measured by VAS were significantly associated with the COMT rs4680 SNP (P=0.042; P=0.016). The co-dominant model for GG verse v. AG genotype (P=0.004) and AG v. AA genotype (P=0.002) has shown to be high risk for FMS. An increased risk of FMS in the dominant model for (AG+AA) v. GG genotype (P=0.001) and no significant difference was found between (GG+AG) v. AA genotype (P=0.08) in the recessive model. The result indicated that A allele considerably increase the risk of FMS (P=0.004) in comparison to the G allele.

CONCLUSION

Conclusions: AA genotype and A allele of the COMT rs4680 SNP were significantly associated with severity in FMS patients and also plays a significant role in the clinical manifestation of this disease.

Evaluation of ApaI and FokI polymorphism of VDR gene and functional characterization in patients with fibromyalgia

Abstract Introduction: Fibromyalgia (FM) is a syndrome of unknown origin characterized by several symptoms, and although its pathogenesis has not been completely elucidated, it seems to be related to inflammatory path-ways and neurochemical changes in the brain. Objective: To evaluate the association between BsmI, ApaI and FokI polymorphisms of the vitamin D receptor (VDR) gene, their polymorphisms, and clinical variables in women with and without FM. Methods: This is a case-control study composed of a group of 53 women with FM and another with 40 women without the disease. The McGill Pain Questionnaire, Fibromyalgia Impact Questionnaire, Pain Visual Analogue Scale and the sit-up test were applied. Real-time PCR was performed to analyze the ApaI and FokI polymorphism. Results: There was a statistical association between race, comorbidity and FM, where 78.4% of the individuals were white and had FM (p < 0.002) and 96.1% had some comorbidity (p < 0.001). Seventy-six point five percent (76.5%) of patients with FM underperformed in the sit-up test (p < 0.001). There was also an association between the genotypic and allele frequencies of the VDR and FM gene Apal and FokI polymorphisms (p < 0.001). In the VDR gene ApaI polymorphism, the CC genotype exhibited a higher frequency in women with FM, the C allele for the Apal polymorphism was 3.33 times more likely, and the FokI polymorphism was 10.9 times more likely to develop FM (p < 0,0001). Conclusion: Women with C allele for ApaI polymorphism are 3.33 times more likely to have FM (95%CI = 1.58-7.02; p = 0.0024), and in FokI polymorphism, the prevalence of T allele is 10.9 times greater (95% CI = 4.76-25.38; p < 0.0001). No significant associations were found in relation to BsmI polymorphism and frequency alleles (p = 0.062 and p = 0.078, respectively).

Attention-deficit hyperactivity disorder symptoms and quality of life in female patients with fibromyalgia

Background/aim

The present study aimed to determine the association between attention-deficit hyperactivity disorder (ADHD) symptoms severity, fibromyalgia (FM) severity, and QoL.

Materials and methods

While the FM group consisted of 113 (74%) patients, the control group consisted of 40 (26%) individuals. FM symptom severity, ADHD symptom severity, and QoL were evaluated using the fibromyalgia impact questionnaire (FIQ), adult ADHD self-report scale (ASRS), and World Health Organization quality of life scale-brief version (WHOQOL-BREF), respectively.

Results

It was found that the FM group had significantly higher scores on the ASRS than the control group (p < 0.05). There was a significant difference in FIQ scores and three WHOQOL-BREF domain scores between the FM alone and comorbid FM/high probability of ADHD groups (p < 0.05). We found a negative correlation between ASRS total scores and all other scale scores (except for the social relationships domain score of the WHOQOL-BREF) and a positive correlation between ASRS total scores and FIQ scores in FM patients. ADHD scores would mediate the relationship between depression severity and QoL.

Conclusions

Our findings indicated that the presence of ADHD symptoms was related to greater FM symptom severity and poorer QoL. Also, ADHD scores would mediate the relationship between depression severity and QoL.

The challenge of differentiating fibromyalgia from small-fiber neuropathy in clinical practice

Fibromyalgia and small fibre neuropathy are two diseases leading to chronic widespread pain, and it is difficult to differentiate them in order to provide appropriate care. In this review, we will describe the pathophysiological and clinical differences between fibromyalgia and small fibre neuropathy. In fibromyalgia, pain is increased by dysregulation of central pain processing while small fibre neuropathy pain is related to loss or dysfunction of intraepidermal small nerve fibres. Higher pain intensity; stabbing pain and paraesthesia; allodynia; dry eyes/mouth; changed pattern or sweating on body; skin colour alterations/modifications; reduced hair/nail growth on lower extremities; warm or cold hypoesthesia could be more common in small fibre neuropathy whereas headache or temporo-mandibular disorder point toward fibromyalgia. Length-dependent distribution of pain is common in small fibre neuropathy but can also affect the whole body. Anxiety or depression are common in these two diseases, but post-traumatic stress disorder and physical or sexual abuse in childhood or adulthood suggest fibromyalgia. Inflammatory disease or musculoskeletal disease is frequently reported with fibromyalgia whereas metabolic disorders (especially diabetes mellitus), neurotoxic exposure, Sjogren's syndrome, sarcoidosis, HIV are the main diseases associated with small fibre neuropathy. Skin biopsy, quantitative sensory testing, laser evoked potentials, confocal corneal microscopy or electrochemical skin conductance can help to discriminate between fibromyalgia and small fibre neuropathy.

Fear of pain moderates the relationship between self-reported fatigue and methionine allele of catechol-O-methyltransferase gene in patients with fibromyalgia

Previous research has shown a consistent association among genetic factors, psychological symptoms and pain associated with fibromyalgia. However, how these symptoms interact to moderate genetic factors in fibromyalgia has rarely been studied to date. The present research investigates whether psychological symptoms can moderate the effects of catechol-O-methyltransferase on pain and fatigue. A total of 108 women diagnosed with fibromyalgia and 77 healthy control participants took part in the study. Pain, fatigue, and psychological symptoms (anxiety, depression, pain catastrophizing, fear of pain and fear of movement) were measured by self-report questionnaires. Two types of statistical analyses were performed; the first was undertaken to explore the influences of COMT genotypes on clinical symptoms by comparing patients with fibromyalgia and healthy controls. In the second analysis, moderation analyses to explore the role of psychological symptoms as potential factors that moderate the relationship between pain/fatigue and COMT genotypes were performed. The main results indicated that patients carrying the Met/Met genotype reported significantly higher levels of fatigue than heterozygote carriers (i.e., Met/Val genotype) and higher levels of fatigue, but not significantly different, than Val homozygote carriers. Among patients with fibromyalgia carrying methionine alleles (i.e., Met/Met + Met/Val carriers), only those who scored high on medical fear of pain, experienced an intensified feeling of fatigue. Thus, the present research suggests that fear of pain, as a psychological symptom frequently described in fibromyalgia may act as a moderating factor in the relationship between the Met allele of the COMT gene and the increase or decrease in self-reported fatigue. Although further research with wider patient samples is needed to confirm the present findings, these results point out that the use of psychological interventions focused on affective symptomatology might be a useful tool to reduce the severity of fibromyalgia.

Polymorphisms of brain-derived neurotrophic factor genes are associated with anxiety and body mass index in fibromyalgia syndrome patients

Objective

Fibromyalgia syndrome has been associated with familial clusters although the specific genetic predisposition is not clear. Accordingly, studies concerning genetic factors associated with this disease are important. Brain-derived neurotrophic factor (BDNF) has been shown to play a role in patients with fibromyalgia syndrome, particularly in mediating manifestations of pain and mood-related symptoms. Research on genetic factors, including genetic variations or single nucleotide polymorphisms, especially related to BDNF in fibromyalgia is very limited. Therefore, this study was aiming at determining the association of polymorphisms of BDNF, particularly rs2049046 (A>T) and rs7124442 (A>G), with body mass index (BMI) and mood-related symptoms in FMS.

Results

In fibromyalgia syndrome cases, BDNF polymorphisms were associated with body mass index and anxiety score, specifically rs7124442 (A>G) (Fisher’s exact test χ²; p < 0.05; odds ratio (OR): 1.02) and rs2049046 (A>T) (Fisher’s exact test χ²; p < 0.05; OR: 0.55), respectively. Additionally, patients with fibromyalgia syndrome who have AA (95% CI (8.71, 11.63)) and AT (95% CI (9.32, 11.74)) alleles of rs2049046 showed higher score of anxiety compared to patients with TT (95% CI (3.98, 8.20) allele (ANOVA test; p < 0.01). These results suggest that BDNF polymorphisms (rs7124442 and rs2049046) are associated with body mass index and anxiety symptoms in patients with fibromyalgia syndrome.

Screening for Adult ADHD in Patients with Fibromyalgia Syndrome

Objective

Fibromyalgia syndrome (FMS) is a common chronic pain disorder associated with altered activity of neurotransmitters involved in pain sensitivity such as dopamine, serotonin, and noradrenaline. FMS may significantly impact an individual's functioning due to the presence of chronic pain, fatigue, and cognitive impairment. Dyscognition may be more disabling than the chronic pain but is mostly under-recognized. This study aimed to assess the potential co-occurrence of FMS and adult attention deficit hyperactivity disorder (ADHD), a chronic neurodevelopmental disorder also associated with impaired cognition and dopaminergic function.

Methods

In a cross-sectional observational study, 123 previously confirmed FMS patients were screened for adult ADHD using the World Health Organization Adult ADHD Self Report scale v1.1. The Revised Fibromyalgia Impact Questionnaire (FIQ-R) was used to assess the impact of FMS. Cognitive assessment was based on self-report in accordance with the 2011 modified American College of Rheumatology criteria and the FIQ-R, respectively.

Results

Of the 123 participants, 44.72% (N = 55) screened positive for adult ADHD. Participants with both FMS and a positive adult ADHD screening test scored higher on the FIQ-R score (64.74, SD = 17.66, vs 54.10, SD = 17.10). Self-reported cognitive impairment was rated higher in the combined group (odds ratio = 10.61, 95% confidence interval; 3.77-29.86, P < 0.01).

Conclusions

These results indicate that the co-occurrence of adult ADHD in FMS may be highly prevalent and may also significantly impact the morbidity of FMS. Patients with FMS should be assessed for the presence of adult ADHD.

Obstructive sleep apnea co-morbidity in patients with fibromyalgia: a single-center retrospective analysis and literature review

Background: Fibromyalgia (FM) is a chronic medical condition characterized by widespread pain, sleep disturbance, and cognitive dysfunction. Sleep disorders are thought to play a prominent role in the etiology and symptomatic management of FM, specifically obstructive sleep apnea (OSA). In order to provide collaborative care, we need a better understanding of any overlapping presentation of FM and OSA. We conducted a site-wide review of patients from 2012-2016 to identify FM patients diagnosed with OSA. Methods: Charts were reviewed in patients aged 18 and above from 2012-2016 using ICD codes from a clinical data repository. Intersection of patients with a diagnosis of FM and OSA in clinics of psychiatry, sleep, rheumatology, and other outpatient clinics was compared. Polysomnography order patterns for FM patients were investigated. Results: Co-morbidity was highest in the sleep clinic (85.8%) compared to psychiatry (42.0%), rheumatology (18.7%), and other outpatient clinics (3.6%) (p<0.001). In the rheumatology and other outpatient clinics, 93.5% and 96% of patients respectively, had no polysomnography ordered. Pairwise comparison of co-morbidity in clinics: sleep vs psychiatry, sleep vs rheumatology, sleep vs other clinics, psychiatry vs rheumatology, psychiatry vs other clinics, and rheumatology vs other clinics were statistically significant after applying a Sidak adjustment to the p-values (all p<0.001). Conclusion: Our analysis suggests that there could be a correlation between FM and OSA, and referral to sleep studies is recommended in the management of patients with FM. The varying prevalence of FM patients with co-morbid OSA in sleep clinics when compared to other outpatient clinics suggests a discrepancy in the identification of FM patients with OSA. When properly screened, OSA co-morbidity has the potential to be higher in other outpatient clinics.

Associations Between Bone Mass in Women With Fibromyalgia and Widespread Pressure Pain Hypersensitivity, Tenderness, Perceived Pain Level, and Disability

This study aimed to evaluate the impact of fibromyalgia syndrome (FMS) on bone mass assessed by calcaneal quantitative ultrasound (QUS) in pre- and postmenopausal women and determine whether there are associations between bone status and pressure pain thresholds (PPTs), tender point counts (TPCs), self-reported global pain, or disease severity. Ninety-five women with a diagnosis of FMS and 108 healthy controls matched on menopause status were included in this cross-sectional study. PPT and TPC were measured by algometry pressure. Self-reported global pain and disease severity were evaluated by Visual Analogue Scale and Fibromyalgia Impact Questionnaire, respectively. Bone mass was assessed with calcaneus QUS. Broadband ultrasound attenuation (BUA; dB/MHz) and speed of sound (SOS; m/s) were significantly lower in the FMS patients compared with controls ( p = .027 and p = .003, respectively). Linear regression analysis revealed that all PPTs were significantly associated with the BUA parameter after adjustments for body mass index (BMI), menopause status, and physical activity in women with FMS ( p < .05). TPC was also significantly associated with BUA after adjustments for covariables (β = .241, 95% confidence interval [0.333, 3.754], p = .020). No significant differences were found between any QUS measurements and global pain or disease severity. Calcaneal BUA and SOS values were lower in women with FMS compared to healthy controls, and decreased pain thresholds and higher TPCs were associated with lower calcaneal BUA values. Low pain thresholds might be independent predictors for low bone mass in FMS women.

Psychological impact of fibromyalgia: current perspectives

Fibromyalgia syndrome (FMS) is a chronic disorder characterized by widespread and persistent musculoskeletal pain and other frequent symptoms such as fatigue, insomnia, morning stiffness, cognitive impairment, depression, and anxiety. FMS is also accompanied by different comorbidities like irritable bowel syndrome and chronic fatigue syndrome. Although some factors like negative events, stressful environments, or physical/emotional traumas may act as predisposing conditions, the etiology of FMS remains unknown. There is evidence of a high prevalence of psychiatric comorbidities in FMS (especially depression, anxiety, borderline personality, obsessive-compulsive personality, and post-traumatic stress disorder), which are associated with a worse clinical profile. There is also evidence of high levels of negative affect, neuroticism, perfectionism, stress, anger, and alexithymia in FMS patients. High harm avoidance together with high self-transcendence, low cooperativeness, and low self-directedness have been reported as temperament and character features in FMS patients, respectively. Additionally, FMS patients tend to have a negative self-image and body image perception, as well as low self-esteem and perceived self-efficacy. FMS reduces functioning in physical, psychological, and social spheres, and also has a negative impact on cognitive performance, personal relationships (including sexuality and parenting), work, and activities of daily life. In some cases, FMS patients show suicidal ideation, suicide attempts, and consummated suicide. FMS patients perceive the illness as a stigmatized and invisible disorder, and this negative perception hinders their ability to adapt to the disease. Psychological interventions may constitute a beneficial complement to pharmacological treatments in order to improve clinical symptoms and reduce the impact of FMS on health-related quality of life.

The effect of cryotherapy on fibromyalgia: a randomised clinical trial carried out in a cryosauna cabin

Evidence of symptomatic treatment for fibromyalgia (FM) is very low. Whole body cryotherapy (WBC) modulates different neurotransmitters, which might have a role in pain alleviation and could exert an effect on FM. Our aim was to evaluate the efficacy of WBC for the control of pain and impact of disease in FM. For this we run an open, randomized, crossover trial of Cryosense TCT™ cabin vs rest. Patients with FM according to ACR criteria were recruited consecutively from general practices. Trial endpoints were change (∆) in pain after 2 and 4 weeks, measured by a visual analogue scale (VAS), ∆ burden of disease, evaluated by the Fibromyalgia Impact Questionnaire (FIQ), and severity of FM, measured by the Combined Index of Severity of Fibromyalgia (ICAF). Within group differences, sequence and period effects were tested with Student's t or Mann-Whitney U tests. Multiple linear regression models were used to adjust effect by baseline differences between groups. Sixty patients were included in the trial. A period effect was noted, with residual effect of WBC; therefore, only results from the first sequence were analysed. ∆VAS pain, ∆FIQ and ∆ICAF scores were significantly larger in the WBC group after the first period (3.0 vs 0.3 in ∆VAS pain; 32.1 vs 0.4 in ∆FIQ; 13.7 vs 0.07 in ∆ICAF; all p < 0.001), and were confirmed after adjustment. In conclusion, WBC with a Cryosense TCT cabin may be a useful adjuvant therapy for FM; further studies on long-term effect and compared to other physical therapies are warranted.Trial registration NCT03425903.

Assessment of medical practitioners' knowledge of fibromyalgia in Saudi Arabia

Background:

Fibromyalgia (FM), a relatively common disease, is difficult to diagnose owing to its subjective symptoms and poor knowledge among medical practitioners. The purpose of this study was to assess the knowledge regarding FM among medical practitioners in Saudi Arabia and the need for educational programs at the undergraduate level.

Subjects and Methods:

An online survey was administered to physicians, nurses, and technologist/technicians in different regions of the country. Responses were obtained from 104 medical practitioners. Knowledge regarding FM including clinical symptoms, diagnosis, and treatment was assessed.

Results:

Only 26% of the respondents reported that FM was part of their undergraduate curriculum, and only 8.7% attended educational programs about FM. (Approximately 50% of the medical practitioners either referred FM patients to unrelated specialty or did not know whom to refer these patients to). Only 33.7% of the respondents were familiar with the diagnostic criteria. Physiotherapy (69.4%) and pharmacological treatment (63.9%) were predominantly reported as the appropriate treatment.

Conclusions:

Knowledge regarding FM among medical practitioners in Saudi Arabia is poor. Further education at the undergraduate level is needed to improve knowledge and avoid delays in diagnosis and treatment.

New insights into the genetics of fibromyalgia

Although debate on the concept of fibromyalgia (FM) has been vigorous ever since the classification criteria were first published, FM is now better understood and has become recognized as a disorder. Recently, FM has come to be considered a major health problem, affecting 1% to 5% of the general population. As familial aggregations have been observed among some FM patients, genetic research on FM is logical. In fact, genome-wide association studies and linkage analysis, and studies on candidate genes, have uncovered associations between certain genetic factors and FM. Genetic susceptibility is now considered to influence the etiology of FM. At the same time, novel genetic techniques, such as microRNA analysis, have been used in attempts to improve our understanding of the genetic predisposition to FM. In this article, we review recent advances in, and continuing challenges to, the identification of genes contributing to the development of, and symptom severity in, FM.

Association between low bone mineral density and fibromyalgia: a meta-analysis

We aimed to evaluate the relationship between bone mineral density (BMD) and fibromyalgia (FM). Meta-analyses were performed comparing BMD in FM patients and healthy controls, and in FM patients in subgroups based on ethnicity, BMD site, age, sex, and measurement method. Twelve studies including 695 FM patients and 784 controls were selected. Meta-analysis by ethnicity revealed a significantly lower BMD in the FM group in Caucasian populations [standardized mean difference (SMD) = -0.144, 95% CI = -0.271-(-0.017), p = 0.026], but not in Turkish populations. Subgroup analysis by BMD site showed that BMD was significantly lower in the FM group than in the control group in the lumbar spine [SMD = -0.588 (medium), 95% CI = -1.142-(-0.033), p = 0.038], but not in the femur neck and hip. Stratification by measurement method revealed a significantly lower BMD in the FM group by dual X-ray absorptiometry and dual-photon absorptiometry [SMD = -0.531 (medium), 95% CI = -1.040-(-0.023), p = 0.041; SMD = -0.315 (small), 95% CI = -0.544-(-0.085), p = 0.007, respectively], but not by quantitative ultrasound, but not by quantitative ultrasound. Subgroup analysis by sex, menopause status, and age revealed a significantly lower BMD in the female FM group [SMD = -0.588 (medium), 95% CI = -1.142-(-0.033), p = 0.038], but not in the pre-menopausal group and the group greater than mean age 50 years old. Our meta-analysis demonstrated that BMD was significantly lower in FM patients in Caucasian and female populations.

Elevated basal serum tryptase identifies a multisystem disorder associated with increased TPSAB1 copy number

Elevated basal serum tryptase levels are present in 4-6% of the general population, but the cause and relevance of such increases are unknown. Previously, we described subjects with dominantly inherited elevated basal serum tryptase levels associated with multisystem complaints including cutaneous flushing and pruritus, dysautonomia, functional gastrointestinal symptoms, chronic pain, and connective tissue abnormalities, including joint hypermobility. Here we report the identification of germline duplications and triplications in the TPSAB1 gene encoding α-tryptase that segregate with inherited increases in basal serum tryptase levels in 35 families presenting with associated multisystem complaints. Individuals harboring alleles encoding three copies of α-tryptase had higher basal serum levels of tryptase and were more symptomatic than those with alleles encoding two copies, suggesting a gene-dose effect. Further, we found in two additional cohorts (172 individuals) that elevated basal serum tryptase levels were exclusively associated with duplication of α-tryptase-encoding sequence in TPSAB1, and affected individuals reported symptom complexes seen in our initial familial cohort. Thus, our findings link duplications in TPSAB1 with irritable bowel syndrome, cutaneous complaints, connective tissue abnormalities, and dysautonomia.

Relationship between FokI polymorphism in the vitamin D receptor gene and fibromyalgia syndrome

AIM

The aim of this study was to evaluate the vitamin D receptor (VDR) gene FokI polymorphism frequencies distribution in subjects with fibromyalgia syndrome (FMS) compared to healthy controls.

METHOD

Using a case-control design, 100 female patients, who were diagnosed with FMS according to the American College of Rheumatology criteria and 100 healthy female subjects were enrolled in this study. FokI polymorphisms of the VDR gene were analyzed by restriction fragment length polymorphisms (RFLP) in both groups.

RESULTS

No significant differences in the frequencies distribution of both genotype and alleles of the FokI polymorphism in the VDR gene were observed between the two groups.

CONCLUSION

The relationship between VDR gene FokI polymorphism and FMS, particularly in Turkish women, could not be determined in this study. However, further studies with larger patient numbers may be needed to prove a relation between VDR gene polymorphism and FMS.

Clinical utility, safety, and efficacy of pregabalin in the treatment of fibromyalgia

Fibromyalgia is a chronic debilitating medical syndrome with limited therapeutic options. Pregabalin, an anticonvulsant and α-2-Δ subunit receptor ligand, is one of the anchor drugs approved by the US Food and Drug Administration for the treatment of fibromyalgia. The drug has shown clinically meaningful benefits across multiple symptom domains of fibromyalgia. Efficacy of pregabalin in fibromyalgia pain has been evaluated in at least five high-quality randomized trials, two long-term extension studies, a meta-analysis, a Cochrane database systematic review, and several post hoc analyses. These studies also hint towards a meaningful benefit on sleep, functioning, quality of life, and work productivity. Side effects of pregabalin, although common, are mild to moderate in intensity. They are noted early during therapy, improve or disappear with dose reduction, and are not usually life- or organ threatening. In most patients, tolerance develops to the most common side effects, dizziness, and somnolence, with time. With close clinical monitoring at initiation or dose titration, pregabalin can be effectively used in primary care setting. Pregabalin is cost saving with long-term use and its cost-effectiveness profile is comparable, if not better, to that of other drugs used in fibromyalgia. In the present era of limited therapeutic options, pregabalin undoubtedly retains its role as one of cardinal drugs used in the treatment of fibromyalgia. This review intends to discuss the clinical utility of pregabalin in the management of fibromyalgia with a focus on efficacy, safety, and cost-effectiveness.

Musculoskeletal pain is associated with restless legs syndrome in young adults

BACKGROUND

In recent years, there is considerable evidence of a relationship between the sensorimotor disorder restless legs syndrome (RLS) and pain disorders, including migraine and fibromyalgia. An association between multi-site pain and RLS has been reported in adult women. In the current study, we explored the association between musculoskeletal (MSK) pain and RLS in a large cohort of young adults.

METHODS

Twenty two year olds (n = 1072), followed since birth of part of the Western Australian Pregnancy Cohort (Raine) Study, provided data on MSK pain (duration, severity, frequency, number of pain sites). RLS was considered present when 4 diagnostic criteria recommended by the International Restless Legs Syndrome Study Group were met (urge to move, dysaesthesia, relief by movement, worsening symptoms during the evening/night) and participants had these symptoms at least 5 times per month. Associations between MSK pain and RLS were analyzed by multivariable logistic regression with bias-corrected bootstrapped confidence intervals, with final models adjusted for sex, psychological distress and sleep quality.

RESULTS

The prevalence of RLS was 3.0 % and MSK pain was reported by 37.4 % of the participants. In multivariable logistic regression models, strong associations were found between RLS-diagnosis and long duration (three months or more) of MSK pain (odds ratio 3.6, 95 % confidence interval 1.4-9.2) and reporting three or more pain sites (4.9, 1.6-14.6).

CONCLUSIONS

Different dimensions of MSK pain were associated with RLS in young adults, suggestive of shared pathophysiological mechanisms. Overlap between these conditions requires more clinical and research attention.

Food intake assessment and quality of life in women with fibromyalgia

OBJECTIVE

To compare the food intake of women with and without fibromyalgia and verify if the food intake of patients with fibromyalgia interferes with the pain and quality of life.

METHODS

Study participants were women with fibromyalgia (FM) seen in Fibromyalgia Outpatient Clinic, Hospital das Clínicas/UFPR and a control group (CT) with healthy women. Data collection was conducted from March to October 2012. For the assessment of food intake we used the Food Registration and the analyzed items were total calories, carbohydrates, proteins, lipids, vitamins (A, C, B12, D and E) and minerals (folate, selenium, zinc, iron, calcium and magnesium). The software used was Avanutri Online(®). To evaluate the quality of life, the Fibromyalgia Impact Questionnaire (FIQ) and pain threshold were used.

RESULTS

43 patients with FM and 44 healthy women were evaluated. CT group showed a mean consumption of nutrients greater than FM group except for iron. However, only caloric intake, carbohydrates, proteins and lipids in grams and percentage of lipids, vitamin A, E, B12, folate, selenium and calcium were statistically significant. In FM group, there was a negative correlation between vitamin E and FIQ and a positive correlation between percentage of protein and pain threshold.

CONCLUSION

Women with FM showed a lower qualitative and quantitative intake in comparison with CT group. Only vitamin E correlated with quality of life and percentage of protein in the diet with sensation of pain.

Exploring Genetic Susceptibility to Fibromyalgia

Fibromyalgia (FM) affects 1% to 5% of the population, and approximately 90% of the affected individuals are women. FM patients experience impaired quality of life and the disorder places a considerable economic burden on the medical care system. With the recognition of FM as a major health problem, many recent studies have evaluated the pathophysiology of FM. Although the etiology of FM remains unknown, it is thought to involve some combination of genetic susceptibility and environmental exposure that triggers further alterations in gene expression. Because FM shows marked familial aggregation, most previous research has focused on genetic predisposition to FM and has revealed associations between genetic factors and the development of FM, including specific gene polymorphisms involved in the serotonergic, dopaminergic, and catecholaminergic pathways. The aim of this review was to discuss the current evidence regarding genetic factors that may play a role in the development and symptom severity of FM.

Meta-analysis reveals a lack of association between a common catechol-O-methyltransferase (COMT) polymorphism val¹⁵⁸met and fibromyalgia

This study is to evaluate the association between the catechol-O-methyltransferase (COMT) gene val(158)met polymorphism and FM risk. We performed a meta-analysis of 8 case-control studies that included 589 FM cases and 527 case-free controls. We assessed the strength of the association, using odds ratios (ORs) with 95% confidence intervals (CIs). Overall, this meta-analysis showed that the COMT gene val(158)met polymorphism was not associated with FM risk in all genetic models, i.e., allele (met vs. val: OR=1.46, 95% CI=0.80-2.66, P heterpgeneity<0.001), homozygous (met/met vs. val/val: OR=1.72, 95% CI=0.61-4.87, P heterpgeneity<0.001), heterozygous (val/met vs. val/val: OR=1.25, 95% CI=0.82-1.92, P heterpgeneity=0.050), recessive (met/met vs. val/val+val/met: OR=1.52, 95% CI=0.60-3.86, P heterpgeneity<0.001) and dominant model (met/met+val/met vs. val/val: OR=1.52, 95% CI=0.80-2.90, P heterpgeneity<0.001). Similarly, there were no significant associations in the subgroup analyses by ethnicity and HWE. No publication bias was found in the present study. This meta-analysis suggests that the COMT gene val(158)met polymorphism is not associated with FM risk. Further large and well-designed studies are needed to confirm this association.

An insight into the gastrointestinal component of fibromyalgia: clinical manifestations and potential underlying mechanisms

Fibromyalgia syndrome is characterized by chronic generalized pain accompanied by a broad symptomatologic spectrum. Besides chronic fatigue, sleep disturbances, headaches and cognitive dysfunction that are extensively described in the literature, a considerable proportion of patients with fibromyalgia experience gastrointestinal symptoms that are commonly overlooked in the studies that are not specifically dedicated to evaluate these manifestations. Nevertheless, various attempts were undertaken to explore the gastrointestinal dimension of fibromyalgia. Several studies have demonstrated an elevated comorbidity of irritable bowel syndrome (IBS) among patients with fibromyalgia. Other studies have investigated the frequency of presentation of gastrointestinal symptoms in fibromyalgia in a nonspecific approach describing several gastrointestinal complaints frequently reported by these patients such as abdominal pain, dyspepsia and bowel changes, among others. Several underlying mechanisms that require further investigation could serve as potential explanatory hypotheses for the appearance of such manifestations. These include sensitivity to dietary constituents such as gluten, lactose or FODMAPs or alterations in the brain-gut axis as a result of small intestinal bacterial overgrowth or subclinical enteric infections such as giardiasis. The gastrointestinal component of fibromyalgia constitutes a relevant element of the multidisciplinary pathophysiologic mechanisms underlying fibromyalgia that need to be unveiled, as this would contribute to the adequate designation of relevant treatment alternatives corresponding to these manifestations.

Association between the COMT Val158Met polymorphism and fibromyalgia susceptibility and fibromyalgia impact questionnaire score: a meta-analysis

The aim of this study was to explore whether the catechol-O-methyltransferase (COMT) Val158Met polymorphism is associated with susceptibility to fibromyalgia and fibromyalgia impact questionnaire (FIQ) score in fibromyalgia patients. We conducted a meta-analysis of the associations of the COMT Val158Met polymorphism with fibromyalgia risk as well as FIQ score in fibromyalgia patients. A total of 993 fibromyalgia patients and 778 controls from 10 studies on the COMT Val158Met polymorphism and 538 fibromyalgia patients from 5 studies on the COMT Val158Met polymorphism and FIQ score were included in this meta-analysis. The meta-analysis revealed an association between fibromyalgia and the COMT Met/Met + Val/Met genotype in all study subjects (odds ratio (OR) 1.635, 95 % confidence interval (CI) 1.029-2.597, p = 0.037). However, stratification by ethnicity indicated no association between the Met/Met + Val/Met genotype and fibromyalgia in the European and Turkish populations (OR 1.202, 95 % CI 0.876-1.649, p = 0.255; OR 2.132, 95 % CI 0.764-5.949, p = 0.148, respectively). Analysis using other genetic models showed no association between the COMT Val158Met polymorphism and fibromyalgia. The meta-analysis also revealed that the FIQ score was significantly higher in individuals with the COMT Met/Met genotype than in those with the Val/Val genotype [weighted mean difference (WMD) = 14.39, 95 % CI 3.316-25.48, p = 0.011] and the Val/Met genotype (WMD = 5.108, 95 % CI 2.212-4.891, p = 0.021). This meta-analysis identified an association between fibromyalgia risk and the COMT Val158Met polymorphism as well as the FIQ score in fibromyalgia patients.

Synaptosomal-associated protein 25 (Snap-25) gene polymorphism frequency in fibromyalgia syndrome and relationship with clinical symptoms

Background

SNAP-25 protein is contributory to plasma membrane and synaptic vesicle fusions that are critical points in neurotransmission. SNAP-25 gene is associated with behavioral symptoms, personality and psychological disorders. In addition, SNAP-25 protein can be related to different neurotransmitter functions due to its association with vesicle membrane transition and fusion. This is important because neurologic, cognitive, and psychologic disorders in fibromyalgia syndrome (FMS) can be related to this function. This relationship may be enlightening for etiopathogenesis of FMS and treatment approaches. We aimed to study a SNAP-25 gene polymorphism, which is related to many psychiatric diseases, and FMS association in this prospective study.

Methods

We included 71 patients who were diagnosed according to new criteria and 57 matched healthy women in this study. Both groups were evaluated regarding age, height, weight, BMI, education level, marital and occupational status. A new diagnosis of FMS was made from criteria scoring, SF-36, Beck depression scale, and VAS that were applied to the patient group. SNAP-25 gene polymorphism and disease activity score correlations were compared.

Results

Mean age was 38±5,196 and 38.12±4.939 in patient and control groups, respectively (p=0.542). No significant difference was found between groups regarding age, height, weight, BMI, education level, marital or occupational status (p > 0.05). Ddel T/C genotype was significantly higher in the patient group (p = 0.009). MnlI gene polymorphism did not show a correlation with any score whereas a significant correlation was found between Ddel T/C genotype and Beck depression scale and VAS score (p < 0.05).

Conclusion

FMS etiopathogenesis is not clearly known. Numerous neurologic, cognitive and psychological disorders were found during studies looking at cause. Our study showed increased SNAP-25 Ddel T/C genotype in FMS patients compared to the control group, which is related to behavioral symptoms, personality and psychological disorders in FMS patients.

2012 Canadian Guidelines for the diagnosis and management of fibromyalgia syndrome: executive summary

BACKGROUND

Recent neurophysiological evidence attests to the validity of fibromyalgia (FM), a chronic pain condition that affects >2% of the population.

OBJECTIVES

To present the evidence-based guidelines for the diagnosis, management and patient trajectory of individuals with FM.

METHODS

A needs assessment following consultation with diverse health care professionals identified questions pertinent to various aspects of FM. A literature search identified the evidence available to address these questions; evidence was graded according to the standards of the Oxford Centre for Evidence-Based Medicine. Drafted recommendations were appraised by an advisory panel to reflect meaningful clinical practice.

RESULTS

The present recommendations incorporate the new clinical concepts of FM as a clinical construct without any defining physical abnormality or biological marker, characterized by fluctuating, diffuse body pain and the frequent symptoms of sleep disturbance, fatigue, mood and cognitive changes. In the absence of a defining cause or cure, treatment objectives should be patient-tailored and symptom-based, aimed at reducing global complaints and enhancing function. Healthy lifestyle practices with active patient participation in health care forms the cornerstone of care. Multimodal management may include nonpharmacological and pharmacological strategies, although it must be acknowledged that pharmacological treatments provide only modest benefit. Maintenance of function and retention in the workforce is encouraged.

CONCLUSIONS

The new Canadian guidelines for the treatment of FM should provide health professionals with confidence in the complete care of these patients and improve clinical outcomes.

The impact of thyroid autoimmunity on arterial stiffness in postmenopausal patients with fibromyalgia

OBJECTIVE

The exact mechanism of arterial stiffness in fibromyalgia (FM) remains unclear. The present study aimed to evaluate the association between thyroid function and markers of arterial function in postmenopausal FM patients.

METHODS

This study included 163 postmenopausal FM patients without any known cardiovascular diseases and within a normal reference range of thyroid-stimulating hormone (TSH) level. Clinical parameters including the Fibromyalgia Impact Questionnaire (FIQ), the pain visual analogical scale (VAS) and tender point counts were measured. Vascular function was assessed by brachial-ankle pulse wave velocity (baPWV) and flow-mediated dilation (FMD). We evaluated the associations between arterial markers and serum TSH, free thyroxin, as well as serum thyroidperoxidase autoantibody (TPO Ab).

RESULTS

Patients with a high baPWV (≥ 1490 cm/s) showed more positive TPO Ab (65% vs. 10%, P = 0.006) than those with a normal baPWV. Additionally, the baPWV values of patients with positive TPO Ab were significantly different from those with negative TPO Ab. Age, FIQ and TPO Ab were significantly correlated with baPWV and FMD (all P < 0.05). Multiple linear regression analysis revealed that the only significant predictors of baPWV were age, FIQ and the presence of TPO Ab after adjustment for traditional risk factors. A significant association was also found between FMD and positive TPO Ab.

CONCLUSION

Age, functional status and presence of TPO Ab were significantly associated with increased arterial stiffness in postmenopausal FM patients. Given the combined thyroid autoimmunity in FM patients, a re-evaluation of the effects on the vasculature may be necessary.

An intricate relationship between pain and depression: clinical correlates, coactivation factors and therapeutic targets

INTRODUCTION

An apparent clinical relationship between pain and depression has long been recognized, which makes an enormous impact on the individual health care. At present, the practical implication of such overlapping symptomatology between pain and depression is not clear, but the prevalence estimates for depression are substantially inflated among patients with chronic pain and vice versa. This interaction has been labeled as the depression-pain syndrome or depression-pain dyad.

AREAS COVERED

This article discusses the neurobiological substrates and neuroanatomical pathways involved in pain-depression dyad along with newer therapeutic targets.

EXPERT OPINION

Several key themes emerged from our review of the relationship between depression and pain. First, the diagnosis of depression in pain or vice versa is particularly challenging, and the development of better diagnostic framework that involves both pain and depression is particularly required. Secondly, the entwined relationship between pain and depression supports the possibility of common coactivating factors that results in their neurophysiological overlap. A broad understanding of the role played by the central nervous system (CNS) in the processing of pain and depression may eventually lead to the introduction of triple reuptake inhibitors, agomelatine, vilazodone and ketamine with novel mechanism of action, hence appear to be of promising potential for pain with depression.

Excessive peptidergic sensory innervation of cutaneous arteriole-venule shunts (AVS) in the palmar glabrous skin of fibromyalgia patients: implications for widespread deep tissue pain and fatigue

OBJECTIVE

To determine if peripheral neuropathology exists among the innervation of cutaneous arterioles and arteriole-venule shunts (AVS) in fibromyalgia (FM) patients.

SETTING

Cutaneous arterioles and AVS receive a convergence of vasoconstrictive sympathetic innervation, and vasodilatory small-fiber sensory innervation. Given our previous findings of peripheral pathologies in chronic pain conditions, we hypothesized that this vascular location may be a potential site of pathology and/or serotonergic and norepinephrine reuptake inhibitors (SNRI) drug action.

SUBJECTS

Twenty-four female FM patients and nine female healthy control subjects were enrolled for study, with 14 additional female control subjects included from previous studies. AVS were identified in hypothenar skin biopsies from 18/24 FM patient and 14/23 control subjects.

METHODS

Multimolecular immunocytochemistry to assess different types of cutaneous innervation in 3 mm skin biopsies from glabrous hypothenar and trapezius regions.

RESULTS

AVS had significantly increased innervation among FM patients. The excessive innervation consisted of a greater proportion of vasodilatory sensory fibers, compared with vasoconstrictive sympathetic fibers. In contrast, sensory and sympathetic innervation to arterioles remained normal. Importantly, the sensory fibers express α2C receptors, indicating that the sympathetic innervation exerts an inhibitory modulation of sensory activity.

CONCLUSIONS

The excessive sensory innervation to the glabrous skin AVS is a likely source of severe pain and tenderness in the hands of FM patients. Importantly, glabrous AVS regulate blood flow to the skin in humans for thermoregulation and to other tissues such as skeletal muscle during periods of increased metabolic demand. Therefore, blood flow dysregulation as a result of excessive innervation to AVS would likely contribute to the widespread deep pain and fatigue of FM. SNRI compounds may provide partial therapeutic benefit by enhancing the impact of sympathetically mediated inhibitory modulation of the excess sensory innervation.

Chronic widespread pain: from peripheral to central evolution

Chronic pain can be classified as localised, regional or widespread, and its high prevalence in the general population seems to increase with age. The majority of cases present with musculoskeletal pain. The conditions associated with chronic widespread pain (CWP) are highly burdensome as their characteristic symptoms may include multifocal pain, fatigue, insomnia, memory difficulties and a higher rate of concomitant mood disorders. After many years of debate, it is still unclear whether CWP (central sensitisation) is an entirely explainable neurotransmitter-related process or is partially or totally due to individual cognitive experiences and evaluations. The two models (neurochemical and biopsychosocial) also affect our ability to find therapeutic answers.

Central pain mechanisms in chronic pain states--maybe it is all in their head

Mechanisms underlying chronic pain differ from those underlying acute pain. In chronic pain states, central nervous system (CNS) factors appear to play particularly prominent roles. In the absence of anatomical causes of persistent pain, medical sub-specialities have historically applied wide-ranging labels (e.g., fibromyalgia (FM), irritable bowel syndrome, interstitial cystitis and somatisation) for what now is emerging as a single common set of CNS processes. The hallmark of these 'centrally driven' pain conditions is a diffuse hyperalgesic state identifiable using experimental sensory testing, and corroborated by functional neuroimaging. The characteristic symptoms of these central pain conditions include multifocal pain, fatigue, insomnia, memory difficulties and a higher rate of co-morbid mood disorders. In contrast to acute and peripheral pain states that are responsive to non-steroidal anti-inflammatory drugs (NSAIDs) and opioids, central pain conditions respond best to CNS neuromodulating agents, such as serotonin-norepinephrine reuptake inhibitors (SNRIs) and anticonvulsants.