Neuroendocrine perturbations in fibromyalgia and chronic fatigue syndrome

Endocrine Aspects of Pain Pathophysiology: Focus on Adipose Tissue

BACKGROUND

Multiple factors, including neurobiological, hormonal, psychological, and social/cultural norms, influence the manner in which individuals experience pain. Adipose tissue, once considered solely an energy storage site, has been recognized as a significant endocrine organ that produces and releases a range of hormones and cytokines. In recent years, research has highlighted the role of adipose tissue and its endocrine factors in the pathophysiology of pain.

SUMMARY

This narrative review aimed to provide a comprehensive overview of the current knowledge on the endocrine aspects of pain pathophysiology, with a specific focus on adipose tissue. We examine the role of adipokines released by adipose tissue, such as leptin, adiponectin, resistin, visfatin, asprosin in pain perception and response. We also explore the clinical implications of these findings, including the potential for personalized pain management based on endocrine factors and adipose tissue.

KEY MESSAGES

Overall, given this background, this review intended to highlight the importance of understanding the endocrine aspects of pain pathophysiology, particularly focusing on the role of adipose tissue, in the development of chronic pain and adipokines. Better understanding the role of adipokines in pain modulation might have therapeutic implications by providing novel targets for addressing underlying mechanism rather than directly focusing on symptoms for chronic pain, particularly in obese individuals.

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.

Fibromyalgia and Depression in Women: An 1H-NMR Metabolomic Study

Fibromyalgia is a chronic and systemic syndrome characterized by muscle, bone, and joint pain. It is a gender-specific condition with a 9:1 incidence ratio between women and men. Fibromyalgia is frequently associated with psychic disorders affecting the cognitive and emotional spheres. In the reported work, we compared 31 female fibromyalgia patients to 31 female healthy controls. They were analyzed for biochemical clinical parameters, for autoimmune markers, and were subjected to 1H-NMR metabolomics analysis. To identify a correlation between the metabolomic profile and the psychic condition, a subset of 19 fibromyalgia patients was subjected to HAM-A and HAM-D Hamilton depression tests. Multivariate statistical analysis showed the dysmetabolism of several metabolites involved in energy balance that are associated with systemic inflammatory conditions. The severity of depression worsens dysmetabolic conditions; conversely, glycine and glutamate, known for their critical role as neuromodulators, appear to be potential biomarkers of fibromyalgia and are associated with different severity depression conditions.

Theory: Treatments for Prolonged ICU Patients May Provide New Therapeutic Avenues for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

We here provide an overview of treatment trials for prolonged intensive care unit (ICU) patients and theorize about their relevance for potential treatment of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Specifically, these treatment trials generally target: (a) the correction of suppressed endocrine axes, notably through a "reactivation" of the pituitary gland's pulsatile secretion of tropic hormones, or (b) the interruption of the "vicious circle" between inflammation, oxidative and nitrosative stress (O&NS), and low thyroid hormone function. There are significant parallels in the treatment trials for prolonged critical illness and ME/CFS; this is consistent with the hypothesis of an overlap in the mechanisms that prevent recovery in both conditions. Early successes in the simultaneous reactivation of pulsatile pituitary secretions in ICU patients-and the resulting positive metabolic effects-could indicate an avenue for treating ME/CFS. The therapeutic effects of thyroid hormones-including in mitigating O&NS and inflammation and in stimulating the adreno-cortical axis-also merit further studies. Collaborative research projects should further investigate the lessons from treatment trials for prolonged critical illness for solving ME/CFS.

Enabling personal recovery from fibromyalgia - theoretical rationale, content and meaning of a person-centred, recovery-oriented programme

Background

Fibromyalgia (FM) is a contested, chronic widespread pain syndrome on which recommended therapies have short-lasting, moderate effects. Nevertheless, some patients become symptom-free, and their recovery experiences inspired us to develop a patient-centred recovery-oriented programme (PROP) delivered in a group format. Presently, we describe the theoretical rationale, purpose and content of the PROP, and its meanings for clinicians and patients.

Methods

A multidisciplinary clinical team, a leader of a rehabilitation unit, and two researchers coproduced the PROP. Five full-day seminars were arranged to bridge research and clinical experiences. Qualitative studies about patients’ illness and recovery experiences and questions by researchers facilitated reflections on clinical experiences. The meaning of the PROP was examined using focus group and individual interviews with patients and clinicians immediately after completing the course and after 1–1.5 years.

Results

The biopsychosocial model displays the research evidence across biological, mental and social impacts of FM, justifying that life stress can be an illness-maintaining factor in FM. The content addresses enabling patients to heal their own life and self by modifying life stress. Patients engage in making sense of the relationship between FM, themselves, and life through exploring, discovering and creating appropriate solutions for their daily social life. The PROP reduced uncertainties and brought a positive attitude and hope to the groups. After 1 year, patients are still engaged in recovery work, experience more good days, and maintain hope for further recovery. By sharing and reflecting on clinical experiences, a unified clinical team was established that continues to develop their competency.

Conclusion

To our knowledge, the PROP is the first programme for patients with FM that results from a process of coproducing knowledge, is based on explicit theoretical rationale, and facilitates a personal experiential recovery process. PROP is found to be meaningful and to work by patients and clinicians.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-021-06295-6.

Hypothesis: Mechanisms That Prevent Recovery in Prolonged ICU Patients Also Underlie Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

Here the hypothesis is advanced that maladaptive mechanisms that prevent recovery in some intensive care unit (ICU) patients may also underlie Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Specifically, these mechanisms are: (a) suppression of the pituitary gland's pulsatile secretion of tropic hormones, and (b) a "vicious circle" between inflammation, oxidative and nitrosative stress (O&NS), and low thyroid hormone function. This hypothesis should be investigated through collaborative research projects.

Rebuilding a tolerable life: narratives of women recovered from fibromyalgia

Introduction: Fibromyalgia syndrome (FMS) is a chronic musculoskeletal pain and fatigue condition. Despite extensive research, there is currently no known therapy leading to a cure for FMS. Although studies have reported that some patients can regain their health, little is known about their personal process of becoming well.Objevtive: This study aimed to explore women's narratives about the process of recovering from FMS.Methods: The empirical material consists of qualitative interviews of eight Norwegian women who all have previously had, but do not have FMS any more. Inspired by a narrative approach we analyzed their experiences of becoming better with a focus on recovery as a meaning-making process.Results: The findings revealed a recovery process consisting of two intertwined narratives that are mutually nurturing each other. The first narrative telling moments of prompting changes refers to events during the recovery process where women understood themselves and their suffering in new ways and thereby enabled them to act in new ways or take further action. The second narrative a mundane process of rebuilding a tolerable daily life refers to a lasting, mundane everyday process of exploration how they initially should act to avoid becoming worse and, later, to promote improvement.Conclusion: Our findings show how the women explain their recovery in terms of overcoming fear of movement, making sense of their symptoms and becoming more active in everyday life. The close analysis reveals a recovery narrative portraying a complex and ambiguous process consisting of small dramas about the efforts trying to rebuild a meaningful life.

Hypothalamic-Pituitary-Adrenal Axis Responses in Women with Endometriosis-Related Chronic Pelvic Pain

Some chronic pain conditions and comorbidities suppress the hypothalamic-pituitary-adrenal (HPA) axis and response to dynamic testing. We measured HPA axis responses to corticotropin-releasing hormone (CRH) administration in relation to chronic pelvic pain and endometriosis. In a cross-sectional study of women (n = 54) with endometriosis-associated chronic pelvic pain (n = 22), chronic pelvic pain alone (n = 12), or healthy volunteers (n = 20), adrenocorticotropic-releasing hormone (ACTH) and cortisol levels were measured at 0, 15, 30, and 45 min after intravenous ovine CRH administration. ACTH and cortisol delta (peak-baseline) and area under the curve (AUC) were compared by study group and assessed for association with race and menstrual and non-menstrual pain severity. HPA axis responses did not differ among the racially diverse groups or in those with pain compared with healthy volunteers. However, when stratified by race, ACTH delta (129.9 ± 130.7 vs. 52.5 ± 66.0 pg/mL; p = 0.003), ACTH AUC (4813 ± 4707 vs. 2290 ± 2900 min*pg/mL; p = 0.013), and cortisol delta (26.3 ± 21.5 vs. 13.2 ± 9.7 μg/mL; p = 0.005) were significantly higher in black (n = 10) than predominately white (non-black) subjects (n = 44; 39/44 white). In analyses among primarily white (non-black) women, greater menstrual pain severity was associated with blunted ACTH delta (p = 0.015) and cortisol delta (p = 0.023), and greater non-menstrual pain severity with blunted cortisol delta (p = 0.017). Neuroendocrine abnormalities in women with chronic pelvic pain may differ by pain manifestations and may vary by race. The higher HPA axis response in black women merits investigation in pelvic pain studies stratified by race. In white (non-black) women experiencing pain, a blunted response was related to pain severity suggesting pain affects women independently of endometriosis lesions.

Exposure to Cold Unmasks Potential Biomarkers of Fibromyalgia Syndrome Reflecting Insufficient Sympathetic Responses to Stress

OBJECTIVES

Fibromyalgia syndrome (FMS) is a chronically painful condition whose symptoms are widely reported to be exacerbated by stress. We hypothesized that female patients with FMS differ from pain-free female controls in their sympathetic responses, a fact that may unmask important biomarkers and factors that contribute to the etiology of FMS.

MATERIALS AND METHODS

In a pilot study, blood pressure (BP), skin temperature, thermogenic activity, circulating glucose, and pain sensitivity of 13 individuals with FMS and 11 controls at room temperature (24°C) were compared with that after exposure to cold (19°C).

RESULTS

When measured at 24°C, BP, skin temperature, blood glucose, and brown adipose tissue (BAT) activity, measured using F-fluorodeoxyglucose positron-emission tomography/computed tomography, did not differ between controls and individuals with FMS. However, after cold exposure (19°C), BP and BAT activity increased in controls but not in individuals with FMS; skin temperature on the calf and arm decreased in controls more than in individiuals with FMS; and circulating glucose was lower in individiuals with FMS than in controls. Pain sensitivity did not change during the testing interval in response to cold.

DISCUSSION

The convergence of the effect of cold on 4 relatively simple measures of thermogenic, cardiovascular, and metabolic activity, each regulated by sympathetic activity, strongly indicate that individuals with FMS have impaired sympathetic responses to stress that are observable and highly significant even when measured in extraordinarily small sample populations. If insufficient sympathetic responses to stress are linked to FMS, stress may unmask and maximize these potential clinical biomarkers of FMS and be related to its etiology.

Review of overlap between thermoregulation and pain modulation in fibromyalgia

Fibromyalgia (FM) syndrome is characterized by widespread pain that is exacerbated by cold and stress but relieved by warmth. We review the points along thermal and pain pathways where temperature may influence pain. We also present evidence addressing the possibility that brown adipose tissue activity is linked to the pain of FM given that cold initiates thermogenesis in brown adipose tissue through adrenergic activity, whereas warmth suspends thermogenesis. Although females have a higher incidence of FM and more resting thermogenesis, they are less able to recruit brown adipose tissue in response to chronic stress than males. In addition, conditions that are frequently comorbid with FM compromise brown adipose activity making it less responsive to sympathetic stimulation. This results in lower body temperatures, lower metabolic rates, and lower circulating cortisol/corticosterone in response to stress--characteristics of FM. In the periphery, sympathetic nerves to brown adipose also project to surrounding tissues, including tender points characterizing FM. As a result, the musculoskeletal hyperalgesia associated with conditions such as FM may result from referred pain in the adjacent muscle and skin.

Assessing Cognitive and Psychomotor Performance in Patients with Fibromyalgia Syndrome

Introduction

Patients with fibromyalgia syndrome (FMS) generally present with chronic widespread pain, accompanied by a range of additional and non-specific symptoms, such as fatigue, disturbed sleep, and cognitive dysfunction, which tend to increase with overall severity. Previous studies have shown moderate cognitive impairment in patients with FMS, but there are few valid data explicitly assessing the relevance of these findings to everyday functions, such as driving ability. Therefore, we studied patients with FMS to assess the impact of FMS on tests that predict driving ability.

Methods

Female patients with FMS were prospectively compared to a historical control group of healthy volunteers. The test battery comprised assessments of visual orientation, concentration, attention, vigilance, motor coordination, performance under stress, and reaction time.

Results

A total of 43 patients were matched to 129 controls. The results indicated that the patients’ psychomotor and cognitive performances were significantly non-inferior when compared to healthy controls (with 0.05% alcohol), with the exception of motor coordination. Patients and healthy controls showed an age-related decline in test performance. Correlations were smaller in patients and reversed for vigilance which was linked to a greater FMS symptom load in younger patients.

Conclusion

The results of the present study demonstrate that, in general, the driving ability of patients with FMS was not inferior to that of healthy volunteers based on a standardized computer-based test battery. However, variables, such as younger age, depression, anxiety, fatigue, pain, and poor motor coordination, likely contribute to the subjective perception of cognitive dysfunction in FMS.

Electronic supplementary material

The online version of this article (doi:10.1007/s40122-014-0028-0) contains supplementary material, which is available to authorized users.

The physiologic effects of pain on the endocrine system

Severe pain has profound physiologic effects on the endocrine system. Serum hormone abnormalities may result and these serve as biomarkers for the presence of severe pain and the need to replace hormones to achieve pain control. Initially severe pain causes a hyperarousal of the hypothalamic-pituitary-adrenal system which results in elevated serum hormone levels such as adrenocorticotropin, cortisol, and pregnenolone. If the severe pain does not abate, however, the system cannot maintain its normal hormone production and serum levels of some hormones may drop below normal range. Some hormones are so critical to pain control that a deficiency may enhance pain and retard healing.

Cortisol and inflammatory processes in ovarian cancer patients following primary treatment: relationships with depression, fatigue, and disability

Elevations in the pro-inflammatory cytokine interleukin-6 (IL-6) and alterations in the anti-inflammatory hormone cortisol have been reported in a variety of cancers. IL-6 has prognostic significance in ovarian cancer and cortisol has been associated with fatigue, disability, and vegetative depression in ovarian cancer patients prior to surgery. Ovarian cancer patients undergoing primary treatment completed psychological self-report measures and collected salivary cortisol and plasma IL-6 prior to surgery, at 6 months, and at 1 year. Patients included in this study had completed chemotherapy and had no evidence of disease recurrence. At 6 months, patients showed significant reductions in nocturnal cortisol secretion, plasma IL-6, and a more normalized diurnal cortisol rhythm, changes that were maintained at 1 year. The reductions in IL-6 and nocturnal cortisol were associated with declines in self-reported fatigue, vegetative depression, and disability. These findings suggest that primary treatment for ovarian cancer reduces the inflammatory response. Moreover, patients who have not developed recurrent disease by 1 year appear to maintain more normalized levels of cortisol and IL-6. Improvement in fatigue and vegetative depression is associated with the normalization of IL-6 and cortisol, a pattern which may be relevant for improvements in overall quality of life for ovarian cancer patients.

Acute psychosocial stress-mediated changes in the expression and methylation of perforin in chronic fatigue syndrome

Perforin (PRF1) is essential for immune surveillance and studies report decreased perforin in chronic fatigue syndrome (CFS), an illness potentially associated with stress and/or infection. We hypothesize that stress can influence regulation of PRF1 expression, and that this regulation will differ between CFS and non-fatigued (NF) controls. We used the Trier Social Stress Test (TSST) as a standardized acute psychosocial stress, and evaluated its effect on PRF1 expression and methylation in CFS (n = 34) compared with NF (n = 47) participants. During the TSST, natural killer (NK) cells increased significantly in both CFS (P = <0.0001) and NF subjects (P = <0.0001). Unlike previous reports, there was no significant difference in PRF1 expression at baseline or during TSST between CFS and NF. However, whole blood PRF1 expression increased 1.6 fold during the TSST in both CFS (P = 0.0003) and NF (P = <0.0001). Further, the peak response immediately following the TSST was lower in CFS compared with NF (P = 0.04). In addition, at 1.5 hours post TSST, PRF1 expression was elevated in CFS compared with NF (whole blood, P = 0.06; PBMC, P = 0.02). Methylation of seven CpG sites in the methylation sensitive region of the PRF1 promoter ranged from 38%–79% with no significant differences between CFS and NF. Although, the average baseline methylation of all seven CpG sites did not differ between CFS and NF groups, it showed a significant negative correlation with PRF1 expression at all TSST time points in both CFS (r = −0.56, P = <0.0001) and NF (r = −0.38, P = <0.0001). Among participants with high average methylation (≥65%), PRF1 expression was significantly lower in CFS than NF subjects immediately following TSST. These findings suggest methylation could be an important epigenetic determinant of inter-individual differences in PRF1 expression and that the differences in PRF1 expression and methylation between CFS and NF in the acute stress response require further investigation.

Glucocorticoid regulation of inflammation and its functional correlates: from HPA axis to glucocorticoid receptor dysfunction

Enhanced susceptibility to inflammatory and autoimmune disease can be related to impairments in HPA axis activity and associated hypocortisolism, or to glucocorticoid resistance resulting from impairments in local factors affecting glucocorticoid availability and function, including the glucocorticoid receptor (GR). The enhanced inflammation and hypercortisolism that typically characterize stress-related illnesses, such as depression, metabolic syndrome, cardiovascular disease, or osteoporosis, may also be related to increased glucocorticoid resistance. This review focuses on impaired GR function as a molecular mechanism of glucocorticoid resistance. Both genetic and environmental factors can contribute to impaired GR function. The evidence that glucocorticoid resistance can be environmentally induced has important implications for management of stress-related inflammatory illnesses and underscores the importance of prevention and management of chronic stress. The simultaneous assessment of neural, endocrine, and immune biomarkers through various noninvasive methods will also be discussed.

Stress exacerbates endometriosis manifestations and inflammatory parameters in an animal model

Women with endometriosis have significant emotional distress; however, the contribution of stress to the pathophysiology of this disease is unclear. We used a rat model of endometriosis to examine the effects of stress on the development of this condition and its influence on inflammatory parameters. Female Sprague-Dawley rats were subjected to swim stress for 10 consecutive days prior to the surgical induction of endometriosis by suturing uterine horn implants next to the intestinal mesentery (endo-stress). Sham-stress animals had sutures only, and an endo-no stress group was not subjected to the stress protocol. At the time of sacrifice on day 60, endometriotic vesicles were measured and colons assessed for macroscopic and microscopic damage. Colonic tissue and peritoneal fluid were collected for inflammatory cell analysis. Endometriosis, regardless of stress, produced a decrease in central corticotropin-releasing factor immunoreactivity, specifically in the CA3 subregion of the hippocampus. Prior exposure to stress increased both the number and severity of vesicles found in animals with endometriosis. Stress also increased colonic inflammation, motility, myeloperoxidase levels, and numbers of mast cells. In summary, prior stress may contribute to the development and severity of endometriosis in this animal model through mechanisms involving cell recruitment (eg, mast cells), release of inflammatory mediators, and deregulation of hypothalamic-pituitary axis responses in the hippocampus.

Mechanisms of aluminum adjuvant toxicity and autoimmunity in pediatric populations

Immune challenges during early development, including those vaccine-induced, can lead to permanent detrimental alterations of the brain and immune function. Experimental evidence also shows that simultaneous administration of as little as two to three immune adjuvants can overcome genetic resistance to autoimmunity. In some developed countries, by the time children are 4 to 6 years old, they will have received a total of 126 antigenic compounds along with high amounts of aluminum (Al) adjuvants through routine vaccinations. According to the US Food and Drug Administration, safety assessments for vaccines have often not included appropriate toxicity studies because vaccines have not been viewed as inherently toxic. Taken together, these observations raise plausible concerns about the overall safety of current childhood vaccination programs. When assessing adjuvant toxicity in children, several key points ought to be considered: (i) infants and children should not be viewed as “small adults” with regard to toxicological risk as their unique physiology makes them much more vulnerable to toxic insults; (ii) in adult humans Al vaccine adjuvants have been linked to a variety of serious autoimmune and inflammatory conditions (i.e., “ASIA”), yet children are regularly exposed to much higher amounts of Al from vaccines than adults; (iii) it is often assumed that peripheral immune responses do not affect brain function. However, it is now clearly established that there is a bidirectional neuro-immune cross-talk that plays crucial roles in immunoregulation as well as brain function. In turn, perturbations of the neuro-immune axis have been demonstrated in many autoimmune diseases encompassed in “ASIA” and are thought to be driven by a hyperactive immune response; and (iv) the same components of the neuro-immune axis that play key roles in brain development and immune function are heavily targeted by Al adjuvants. In summary, research evidence shows that increasing concerns about current vaccination practices may indeed be warranted. Because children may be most at risk of vaccine-induced complications, a rigorous evaluation of the vaccine-related adverse health impacts in the pediatric population is urgently needed.

Restless legs syndrome and conditions associated with metabolic dysregulation, sympathoadrenal dysfunction, and cardiovascular disease risk: a systematic review

Restless legs syndrome (RLS) is a distressing sleep and sensorimotor disorder that affects a large percentage of adults in the western industrialized world and is associated with profound reductions in quality of life. However, the etiology of RLS remains incompletely understood. Enhanced understanding regarding both the antecedents and sequelae of RLS could shed new light on the pathogenesis of RLS. Evidence from an emerging body of literature suggests associations between RLS and diabetes, hypertension, obesity, and related conditions linked to sympathetic activation and metabolic dysregulation, raising the possibility that these factors may likewise play a significant role in the development and progression of RLS, and could help explain the recently documented associations between RLS and subsequent cardiovascular disease. However, the relation between RLS and these chronic conditions has received relatively little attention to date, although potential implications for the pathogenesis and treatment of RLS could be considerable. In this paper, we systematically review the recently published literature regarding the association of RLS to cardiovascular disease and related risk factors characterized by sympathoadrenal and metabolic dysregulation, discuss potential underlying mechanisms, and outline some possible directions for future research.

The effect of repeated restraint stress in pain-related behavior induced by nucleus pulposus applied on the nerve root in rats

INTRODUCTION

Chronic pain has an impact on psychological and social factors. It is known that stress influences physiological and behavioral changes and affects several neurotransmitter and hormonal systems. It is also known that corticosterone is increased by stress. The role of chronic stress in sciatica in lumbar disc herniation (LDH) in rats has not been investigated. The aim of this study was to investigate the effect of the restraint stress (RS) on pain-related behavior induced by application of nucleus pulposus (NP) in rats.

MATERIALS AND METHODS

Adult female Sprague-Dawley rats were divided into six experimental groups (naive group; naive + RS; sham group; sham + RS; autologous nucleus pulposus [NP] applied on the left L5 nerve root [NP group]; and NP + RS group). Von Frey tests were used to test pain-related behavior. Concentrations of plasma corticosterone were measured to assess changes in levels of endogenous corticosterone caused by RS. Expression of ATF-3 in the left L5 DRG was examined by immunohistochemical analyses in each group.

RESULTS

Mechanical withdrawal thresholds of the NP and NP + RS groups were significantly decreased after surgery compared with the naive group. Although the thresholds in the NP group recovered after 28 days, the thresholds in the NP + RS group were significantly decreased during the 42 days after surgery. RS increased the concentration of plasma corticosterone at 21 and 42 days after surgery. In the NP and the NP + RS groups, the expression of ATF-3 was significantly increased at 7 days after surgery. The expression of ATF-3 was sustained for 21 days by RS.

CONCLUSION

Concentrations of plasma corticosterone were increased in three groups that underwent RS. The pain-related behavior persisted for the long term in the LDH model. The expression of ATF-3 in DRG neurons increased for 21 days by RS. These results suggest that RS plays a role in the chronicity of pain-related behavior in the LDH rats.

Biological mechanisms related to the effectiveness of guided imagery for chronic pain

Specific aims of this pilot study were to (a) determine the effect of a guided imagery (GI) intervention over an 8-week period on pain and pain disability in a sample of persons with chronic noncancer pain (CNCP) and (b) analyze the mediating effects of neuroendocrine and neuroimmune functioning on the effectiveness of GI on outcome variables. A simple interrupted time-series design (12-week period) was used. GI was introduced at Week 4 and used daily by 25 participants for the remaining 8 weeks. Measures of pain and pain disability were obtained at the beginning of the study period and at six repeated 2-week intervals. Measures of hypothalamic-pituitary-adrenal (HPA) axis activation (plasma cortisol), immune-mediated analgesia (lymphocyte subset counts and proliferation), and immune-mediated hyperalgesia (interleukin-1β) were obtained at the beginning of the study and at Week 11. Usual pain levels were lower after the introduction of GI at Week 4 (Wilks' λ = 52.31; df = 2, 22; p = .000). Pain disability levels were lower after the introduction of GI at Week 4 (Wilks' λ = 5.98; df = 6, 18; p = .001). Correlation coefficients between change scores of dependent variables and mediating variables were not significant. GI was effective in reducing pain intensity and pain disability over an 8-week period; however, the results did not support the expected effects of decreased HPA axis activation, improved immune-mediated analgesia, and reduced immune-mediated hyperalgesia in mediating these outcomes. These findings may be related to procedural and theoretical issues and limitations related to the study design.

The pathophysiology, diagnosis and treatment of fibromyalgia

Research in fibromyalgia has increased understanding of the possible genetic and environmental factors that could be involved in the etiology of fibromyalgia. There is now substantial evidence for augmentation of central pain processing in fibromyalgia. Because the clinical presentation of fibromyalgia is heterogeneous, treatment recommendations must be individualized for each patient. The rapid growth of trials in fibromyalgia in recent years has resulted in new evidence-based approaches to pharmacological and nonpharmacological treatment.

Pharmacological treatment of fibromyalgia syndrome: new developments

Fibromyalgia is a chronic pain disorder characterized by widespread pain, stiffness, insomnia, fatigue and distress. Several randomized controlled trials (RCTs) have shown moderate effectiveness of pharmacological therapies for fibromyalgia pain. Evidence from these trials suggests that pharmacological therapy can not only improve pain but also fatigue, function and well-being in patients with fibromyalgia. Duloxetine and milnacipran, two highly selective serotonin-norepinephrine (noradrenaline) reuptake inhibitors, and the alpha(2)delta agonist pregabalin have been approved by the US FDA for the treatment of fibromyalgia symptoms. In general, about half of all treated patients seem to experience a 30% reduction of symptoms, suggesting that many patients with fibromyalgia will require additional therapies. Thus, other forms of treatment, including exercise, cognitive behavioural therapies and self-management strategies, may be necessary to achieve satisfactory treatment outcomes. Despite promising results of pilot trials, RCTs with dopamine receptor agonists and sodium channel antagonists have so far been disappointing for patients with fibromyalgia. However, new pharmacological approaches for the treatment of fibromyalgia pain and insomnia using sodium oxybate appear to be promising.

Infection, vaccination, and autoantibodies in chronic fatigue syndrome, cause or coincidence?

Chronic fatigue syndrome (CFS) is a heterogeneous syndrome of unknown etiology and physiopathology. CFS patients complain about disabling fatigue, depression, difficulty with memory, and concomitant skeletal and muscular pain. Interestingly enough, there is certain overlap between CFS symptoms, autoimmune rheumatic disease, and infectious diseases. Certain neuroendocrine-immune abnormalities have also been described, and autoantibodies commonly described in some autoimmune diseases have been found in CFS patients as well. An increasing number of autoantibodies, mainly directed against other nuclear cell components, have been illustrated. Likewise, an association between some infectious agents, antibody production, and later CFS onset has been reported. Similarly, vaccination is depicted as playing an important role in CFS onset. Recently, a case report pointed toward a causal association between silicone breast linkage, hepatitis B virus vaccination, and CFS onset in a previous healthy woman. Such findings suggest that there is a likely deregulation of the immune system influenced by specific agents (infections, vaccination, and products, such as silicone). Evidence suggests that CFS is a complex disease in which several risk factors might interact to cause its full expression. Thus, although different alterations have been found in CFS patients, undoubtedly the main feature is central nervous system involvement with immunological alterations. Therefore, a new term neuro-psycho-immunology must be quoted. New studies based on this concept are needed in order to investigate syndromes, such as CFS, in which immunological alterations are thought to be associated with concomitant psychological and health disturbances.

Risk factors for fibromyalgia: the role of violence against women

The objectives of the study were to analyse the association between fibromyalgia (FM) and violence against women and to explore the association between FM and sociodemographic factors, social support and psychological distress. A case-control study was conducted in a Spanish hospital. Cases were women diagnosed with FM, with no signs of any other type of inflammatory rheumatic disorder, who were seen at the Rheumatology Department of the hospital. Controls were women not diagnosed with FM who were seen at the Ear, Nose and Throat Department of the same hospital. A self-administered anonymous questionnaire was used to gather data on sociodemographic characteristics, violence, social support and psychological distress. Uni-, bi- and multivariate logistic regression analyses were conducted; 287 cases and 287 controls were recruited. The multivariate analysis showed that the probability of presenting FM increased with age (odds ratios (OR) = 1.06; CI95% = 1.03-1.09); that employed women and housewives were more likely to have the syndrome than unemployed women or students (OR = 4.97; CI95% = 1.45-17.02, and OR = 3.47; CI95% = 0.98-12.22, respectively); that the lower the educational level, the higher the probability of having FM; and that psychological distress was positively associated with the syndrome (OR = 4.62; CI95% = 2.68-7.97). Although abuse was more prevalent in cases than in controls, the differences were not statistically significant. However, frequency of abuse was positively and significantly correlated with FM. Although the aetiology of FM is still uncertain, it seems that certain psychosocial factors may be associated with the syndrome. Therefore, an interdisciplinary approach to the treatment of patients affected with this syndrome should be considered.

Fibromyalgia: A Review of Its Pathophysiology and Drug Treatment

The objective of this article is to review the literature related to the pathophysiology of fibromyalgia and the drug therapy used to treat this disease. Fibromyalgia, the second most frequently diagnosed rheumatological disorder, has complex interrelated pathologies that must be addressed to achieve effective symptom control. Central and peripheral sensitization along with neurotransmitter abnormalities play a major role in defining the symptoms associated with this disease. Drug therapy must be multifaceted because no single drug addresses all pathologies. Drug and nondrug therapies showing strong-to-moderate effectiveness should be used to obtain the most benefit.

Stress induces a switch of intracellular signaling in sensory neurons in a model of generalized pain

Stress dramatically exacerbates pain in diseases such as fibromyalgia and rheumatoid arthritis, but the underlying mechanisms are unknown. We tested the hypothesis that stress causes generalized hyperalgesia by enhancing pronociceptive effects of immune mediators. Rats exposed to nonhabituating sound stress exhibited no change in mechanical nociceptive threshold, but showed a marked increase in hyperalgesia evoked by local injections of prostaglandin E(2) or epinephrine. This enhancement, which developed more than a week after exposure to stress, required concerted action of glucocorticoids and catecholamines at receptors located in the periphery on sensory afferents. The altered response to pronociceptive mediators involved a switch in coupling of their receptors from predominantly stimulatory to inhibitory G-proteins (G(s) to G(i)), and for prostaglandin E(2), emergence of novel dependence on protein kinase C epsilon. Thus, an important mechanism in generalized pain syndromes may be stress-induced coactivation of the hypothalamo-pituitary-adrenal and sympathoadrenal axes, causing a long-lasting alteration in intracellular signaling pathways, enabling normally innocuous levels of immune mediators to produce chronic hyperalgesia.

Psychophysical and neurochemical abnormalities of pain processing in fibromyalgia

Fibromyalgia pain is frequent in the general population, but its pathogenesis is only partially understood. Patients with fibromyalgia lack consistent tissue abnormalities but display features of hyperalgesia (increased sensitivity to painful stimuli) and allodynia (lowered pain threshold). Many recent fibromyalgia studies have demonstrated central nervous system (CNS) pain processing abnormalities, including abnormal temporal summation of pain. In the CNS, persistent nociceptive input from peripheral tissues can lead to neuroplastic changes resulting in central sensitization and pain. This mechanism appears to represent a hallmark of fibromyalgia and many other chronic pain syndromes, including irritable bowel syndrome, temporomandibular disorder, migraine, and low back pain. Importantly, after central sensitization has been established, only minimal peripheral input is required for the maintenance of the chronic pain state. Additional factors, including pain-related negative affect and poor sleep have been shown to significantly contribute to clinical fibromyalgia pain. Better understanding of these mechanisms and their relationship to central sensitization and clinical pain will provide new approaches for the prevention and treatment of fibromyalgia and other chronic pain syndromes.

Possible use of repeated cold stress for reducing fatigue in chronic fatigue syndrome: a hypothesis

BACKGROUND

Physiological fatigue can be defined as a reduction in the force output and/or energy-generating capacity of skeletal muscle after exertion, which may manifest itself as an inability to continue exercise or usual activities at the same intensity. A typical example of a fatigue-related disorder is chronic fatigue syndrome (CFS), a disabling condition of unknown etiology and with uncertain therapeutic options. Recent advances in elucidating pathophysiology of this disorder revealed hypofunction of the hypothalamic-pituitary-adrenal axis and that fatigue in CFS patients appears to be associated with reduced motor neurotransmission in the central nervous system (CNS) and to a smaller extent with increased fatigability of skeletal muscle. There is also some limited evidence that CFS patients may have excessive serotonergic activity in the brain and low opioid tone.

PRESENTATION OF THE HYPOTHESIS

This work hypothesizes that repeated cold stress may reduce fatigue in CFS because brief exposure to cold may transiently reverse some physiological changes associated with this illness. For example, exposure to cold can activate components of the reticular activating system such as raphe nuclei and locus ceruleus, which can result in activation of behavior and increased capacity of the CNS to recruit motoneurons. Cold stress has also been shown to reduce the level of serotonin in most regions of the brain (except brainstem), which would be consistent with reduced fatigue according to animal models of exercise-related fatigue. Finally, exposure to cold increases metabolic rate and transiently activates the hypothalamic-pituitary-adrenal axis as evidenced by a temporary increase in the plasma levels of adrenocorticotropic hormone, beta-endorphin and a modest increase in cortisol. The increased opioid tone and high metabolic rate could diminish fatigue by reducing muscle pain and accelerating recovery of fatigued muscle, respectively.

TESTING THE HYPOTHESIS

To test the hypothesis, a treatment is proposed that consists of adapted cold showers (20 degrees Celsius, 3 minutes, preceded by a 5-minute gradual adaptation to make the procedure more comfortable) used twice daily.

IMPLICATIONS OF THE HYPOTHESIS

If testing supports the proposed hypothesis, this could advance our understanding of the mechanisms of fatigue in CFS.

Violence, stress, and somatic syndromes

Syndromes characterized by pain, fatigue, mood disorder, cognitive dysfunction, and sleep disturbance have been referred to as stress-related somatic disorders by virtue of the observation that onset and exacerbation of symptoms occur with stress. These syndromes include but are not limited to fibromyalgia, chronic fatigue syndrome, temporomandibular disorder, and irritable bowel syndrome. As with most chronic illnesses, genetic susceptibility and lifetime environmental exposures play a role in creating vulnerability to disease. Cumulative lifetime stress has been associated with a number of physiologic changes in the brain and body that reflect dysregulated hormonal and autonomic activity. Exposure to the stressor of violence is likely to create a state of vulnerability for the stress-related somatic syndromes and also to contribute to symptom expression and severity. Understanding the relationship between violence, stress, and somatic syndromes will help in clarifying the consequences of violence exposure to long-term health and health-related quality of life.

Functional somatic syndrome: how it could be relevant to rheumatologists

Functional somatic syndrome (FSS) is defined as a group of related syndromes characterized more by symptoms, suffering, and disability than by structural or functional abnormality. The diagnostic criteria and/or symptoms of FSS often overlap, and co-morbidity is commonly found among the diseases of FSS. For example, patients with irritable bowel syndrome often suffer from chronic pain, and a high percentage of co-morbidity can be found with fibromyalgia. Accumulating evidence indicates the presence of visceral and somatic hyperalgesia in FSS as a common feature, and the central sensitization mechanism has been suggested to play an important role in the pathophysiology of FSS. In the present article, the authors introduce the concept of FSS focusing on its possible relevance to rheumatology in terms of pain perception. A possible implication of mast cells and proteinase-activated receptor-2 (PAR-2) in FSS is also reviewed.

Fibromyalgia: diagnosis, pathogenesis, and treatment

Fibromyalgia is characterized by chronic widespread pain and the presence of tender points, often accompanied by several non-specific symptoms, such as fatigue, depressive mood, and sleep disturbances. The apparent overlap between fibromyalgia and other syndromes, such as chronic fatigue and irritable bowel, is not sufficient cause to consider all these syndromes as manifestations of a single syndrome. Fibromyalgia is a multifaceted problem. Central afferent pain amplification and perhaps also impaired descending pain inhibition are supposed to underlie widespread pain. Neuroendocrine perturbations, sleep disturbances, health beliefs, mood disorder, and physical deconditioning play a role in the modulation and perseverance of pain and other symptoms. It is extremely difficult to mitigate chronic generalized pain and to deal with other symptoms in fibromyalgia. A uniform intervention strategy is missing. Essential in the tailored management of fibromyalgia are an enhancement of functional capacities and quality of life, and the symptomatic treatment of individual symptoms such as pain, distress, and sleep disturbances. Rather than analysing monotherapy per se, the objective in future evaluations should be to try to find the combined pharmacological or non-pharmacological treatment of choice for specific subgroups of patients.

Growth Hormone Perturbations in Fibromyalgia: A Review

OBJECTIVE

Fibromyalgia (FM) is a syndrome characterized by chronic widespread pain, fatigue, disrupted sleep, depression, and physical deconditioning. In this article, we review the literature on the normal activity of the hypothalamic-pituitary-growth hormone-insulin-like growth factor-1 (HP-GH-IGF-1) axis and its perturbations in FM subjects.

METHODS

Studies included in this review were accessed through an English language search of Cochrane Collaboration Reviews. Keyword MeSH terms included "fibromyalgia," "growth hormone" (GH), or "insulin-like growth factor-1" (IGF-1).

RESULTS

Twenty-six studies enrolling 2006 subjects were reviewed. Overall, low levels of IGF-1 were found in a subgroup of subjects. Growth hormone stimulation tests often revealed a suboptimal response, which did not always correlate with IGF-1 levels. No consistent defects in pituitary function were found. Of the 3 randomized placebo controlled studies, only 9 months of daily injectable recombinant GH reduced FM symptoms and normalized IGF-1.

CONCLUSIONS

These studies suggest that pituitary function is normal in FM and that reported changes in the HP-GH-IGF-1 axis are most likely hypothalamic in origin. The therapeutic efficacy of supplemental GH therapy in FM requires further study before any solid recommendations can be made.

Fibromyalgia and Overlapping Disorders: The Unifying Concept of Central Sensitivity Syndromes

OBJECTIVES

To discuss fibromyalgia syndrome (FMS) and overlapping conditions, eg, irritable bowel syndrome, headaches, and chronic fatigue syndrome, within the concept of central sensitivity syndromes (CSS).

METHODS

A critical overview of the literature and incorporation of the author's own views.

RESULTS

The concept of CSS seems viable. It is based on mutual associations among the CSS conditions as well as the evidence for central sensitization (CS) among several CSS members. However, such evidence is weak or not available in other members at this time, requiring further studies. The biology of CSS is based on neuroendocrine aberrations, including CS, that interact with psychosocial factors to cause a number of symptoms.

CONCLUSIONS

CSS is an important new concept that embraces the biopsychosocial model of disease. Further critical studies are warranted to fully test this concept. However, it seems to have important significance for new directions for research and patient care involving physician and patient education. Each patient, irrespective of diagnosis, should be treated as an individual considering both the biological and psychosocial contributions to his or her symptoms and suffering.

Novel pharmacotherapy for fibromyalgia

Fibromyalgia is a common disorder that is characterized by chronic widespread pain, tenderness to light palpation, fatigue and sleep disturbances. The present lack of a well-accepted model of the disorder has hampered progress towards adequate treatment. A review of potential models to explain the pathophysiology underlying its primary symptom (i.e., chronic widespread pain) lends insight on the therapeutic potential of novel therapies. Following this, a mechanistic evaluation of those medications that are under consideration for the treatment of the disorder is offered. Adequate treatment will be likely to involve the identification of biologic subgroups within the greater fibromyalgia construct. Key insights from basic research are the basis for increased optimism for effective relief among patients and clinicians.

Normal cerebrospinal fluid levels of hypocretin-1 (orexin A) in patients with fibromyalgia syndrome

BACKGROUND

The hypothalamic neuropeptide hypocretin (orexin) modulates sleep-wake, feeding and endocrine functions. Cerebrospinal fluid (CSF) hypocretin-1 (Hcrt-1) concentrations are low in patients with narcolepsy-cataplexy, a sleep disorder characterized by hypersomnolence and rapid eye movement (REM) sleep abnormalities.

METHODS

We determined CSF Hcrt-1 concentrations of patients with the fibromyalgia syndrome (FMS), a condition characterized by fatigue, insomnia and in some cases daytime hypersomnolence.

RESULTS

Basal CSF levels of Hcrt-1 in FMS did not differ from those in healthy normal controls.

CONCLUSIONS

These findings suggest that abnormally low Hcrt-1 is not a likely cause of fatigue in FMS.

Is further evaluation for growth hormone (GH) deficiency necessary in fibromyalgia patients with low serum insulin-like growth factor (IGF)-I levels?

OBJECTIVE

Fibromyalgia (FM) is characterized by diffuse pain, fatigue, and sleep disturbances; symptoms that resemble the adult growth hormone (GH) deficiency syndrome. Many FM patients have low serum GH levels, with a hypothesized aetiology of dysregulated GH/insulin-like growth factor (IGF)-I axis. The aim of this study was to assess the GH reserve in FM patients with low serum IGF-I levels using the GH-releasing hormone (GHRH)-arginine test.

DESIGN

We retrospectively reviewed the GHRH-arginine data of 77 FM patients with low serum IGF-I levels referred to our tertiary unit over a 4-year period.

RESULTS

Of the 77 FM patients, 13 patients (17%) failed the GHRH-arginine test. Further evaluation with pituitary imaging revealed normal pituitary glands (n=7), coincident microadenomas (n=4), empty sella (n=1) and pituitary cyst (n=1), and relevant medical histories such as previous head injury (n=4), Sheehan's syndrome (n=1), and whiplash injury (n=1). In contrast, the remaining 64 patients (83%) that responded to the GHRH-arginine test demonstrated higher peak GH levels compared to age and BMI-matched controls (n=24).

CONCLUSION

Our data shows that a subpopulation of FM patients with low serum IGF-I levels will fail the GHRH-arginine test. We, thus, recommend that the GH reserve of these patients should be evaluated further, as GH replacement may potentially improve the symptomatology of those with true GH deficiency. Additionally, the increased GH response rates to GHRH-arginine stimulation in the majority of FM patients with low serum IGF-I levels further supports the hypothesis of a dysregulated GH/IGF-I axis in the pathophysiology of FM.

Cytokines and the immune–neuroendocrine network: What did we learn from infection and autoimmunity?

The initial view of the neuroendocrine-immune communication as the brake of immune activation is changing. Recent evidence suggests that the optimization of the body's overall response to infection could be actually the role of the immune-endocrine network. In gradually more complex organisms, the multiplicity of host-pathogen interfaces forced the development of efficient and protective responses. Molecules such as cytokines and Toll-like receptors (TLRs) are distributed both in the periphery and in the brain to participate in a coordinated adaptive function. When sustained release of inflammatory mediators occurs, as in autoimmune diseases, undesirable pathological consequences become evident with different manifestations and outcomes. Clearly, organisms are not well adapted to that disregulated condition yet, suggesting that additional partners within neuroendocrine-immune interactions might emerge from the evolutionary road.