Circadian rhythms of women with fibromyalgia

Melatonin as preemptive analgesic for intraoperative pain

Several anti-inflammatory and analgesic drugs have been used to reduce pain and discomfort during periodontal surgeries. This study evaluates the efficacy of using melatonin and ketorolac for pain prevention during open-flap debridement surgery. This prospective randomized controlled trial was performed in patients who presented with chronic periodontitis after non-surgical periodontal therapy, requiring flap surgery. Group 1: Flap surgery following non-surgical periodontal therapy after one month with no oral administration of analgesic. Group 2: Flap surgery following non-surgical periodontal therapy after one month with oral administration of Ketorolac 400mg one hour prior to the surgery. Group 3: Flap surgery following non-surgical periodontal therapy after one month with oral administration of 2 mg Melatonin one hour prior to the surgery. VAS and FLACC score along with blood pressure, SPO2 and heart rate. Statistical analysis was done using SPSS software. The intragroup comparisons (control-test drug) demonstrated that melatonin and ketorolac showed positive preemptive effect which compared to the control with mean differences significantly different from zero. However, when melatonin and ketorolac were compared there was no significant difference in postoperative pain among patients. The adoption of a preemptive medication protocol using either melatonin or ketorolac may be considered effective for pain and discomfort prevention during and post open-flap debridement surgeries. Melatonin showed similar effect to gold standard ketorolac in terms of its preemptive analgesic effect additional to having anti-inflammatory effect. Further studies are required to standardize the protocol for using melatonin as preemptive analgesic for dental surgical procedures.

A theoretical framework to improve the construct for chronic pain disorders using fibromyalgia as an example

Fibromyalgia (FM) is a frequent, complex condition of chronic musculoskeletal pain with no evidence for biological correlates. For this reason, despite many efforts from the medical community, its construct still appears ill defined. Promising candidate biomarkers are critically reviewed. A research agenda is proposed for developing a clearer construct of FM. The ideal theoretical framework is one of overcoming the illness–disease dichotomy and considering reciprocal interactions between biology and behaviour. This approach may foster research in other fields of pain medicine and of medicine in general.

Salivary cortisol is associated with cognitive changes in patients with fibromyalgia

Fibromyalgia (FM) is a stress-related chronic pain disorder with common cognitive complaints. This study characterized cognitive dysfunction in patients with FM and explored whether these changes are linked to altered cortisol levels. Consecutive 44 patients with FM and 48 healthy controls were enrolled for the assessments of subjective and objective cognitive functions and diurnal levels of salivary cortisol (sampled at awakening, 30 min after awakening, 3 pm, and bedtime). All measurements were compared between the groups and evaluated for clinical correlation. The FM group had more subjective cognitive complaints and performed poorer in objective cognitive testing in memory (delayed recall in Chinese Version Verbal Learning Test and Taylor Complex Figure Test), language (Boston Naming Test), and executive domains (Wisconsin Card Sorting Test) after adjustments for education. The diurnal cortisol levels of patients with FM tended to be lower, especially at 30 min after awakening and bedtime. Moreover, moderate positive correlations existed between the Chinese Version Verbal Learning Test, Boston Naming Test and the morning cortisol levels within the FM group. We suggested the altered cognitive function in FM may be linked to stress maladaptation. Future studies are warranted to elucidate whether stress management improves cognitive performance in patients with FM.

Activity rhythms and clinical correlates in fibromyalgia

The primary aim of this study was to evaluate activity rhythms in fibromyalgia syndrome (FMS) and their association with FMS-related symptoms. We hypothesized that stronger and more consistent activity rhythms would be associated with reduced symptom severity and presentation in FMS. Two hundred ninety-two patients with FMS (mean age = 45.1 ± 11.1; 272 women) provided a 7-day actigraphy recording and responses to questionnaires addressing degree of pain, fatigue, mood, and physical impairment. Using a simple cosine model, we extracted Amplitude (activity range), Phi (time at maximum), Mesor (mean activity), and their variabilities (across days) from each participant's actigraphy. The clinical and actigraphic measures were operationally independent. There was a significant canonical relationship between activity rhythm parameters and clinical FMS measures (r = 0.376, R = 0.14, P < 0.001). The set of Mesor, Amplitude, and Phi activity parameters remained associated with clinical measures when controlled statistically for both demographics and activity variability (P < 0.001). Each activity parameter provided unique discrimination of the clinical set by multivariate test (P = 0.003, 0.018, and 0.007 for Amplitude, Phi, and Mesor, respectively). These results revealed that better pain, fatigue, mood, physical impairment, and sleep outcomes were associated with higher activity range and more rhythmicity (Amplitude), increased mean activity (Mesor), and with earlier timing of peak activity (Phi). Exploratory analyses revealed significantly worse sleep for individuals with low Amplitude and more delayed Phi.

A narrative review on the difficulties associated with fibromyalgia diagnosis

Fibromyalgia presents a clinical enigma as its pathophysiology is not well understood and its symptoms are nonspecific and overlap with many disorders, making its diagnosis a challenge for clinicians and researchers. Efforts have been made to develop a set of diagnostic criteria for this disorder. However, these criteria rely heavily on expert clinician opinion and produce a large heterogeneity within the diagnosed population. With no present specific technique reflecting the underlying pathophysiology of fibromyalgia, a definitive diagnosis of fibromyalgia remains elusive. This review discusses some problems and challenges associated with fibromyalgia diagnosis and presents some novel findings on the pathophysiological nature of fibromyalgia.

The Functional and Clinical Significance of the 24-Hour Rhythm of Circulating Glucocorticoids

Adrenal glucocorticoids are major modulators of multiple functions, including energy metabolism, stress responses, immunity, and cognition. The endogenous secretion of glucocorticoids is normally characterized by a prominent and robust circadian (around 24 hours) oscillation, with a daily peak around the time of the habitual sleep-wake transition and minimal levels in the evening and early part of the night. It has long been recognized that this 24-hour rhythm partly reflects the activity of a master circadian pacemaker located in the suprachiasmatic nucleus of the hypothalamus. In the past decade, secondary circadian clocks based on the same molecular machinery as the central master pacemaker were found in other brain areas as well as in most peripheral tissues, including the adrenal glands. Evidence is rapidly accumulating to indicate that misalignment between central and peripheral clocks has a host of adverse effects. The robust rhythm in circulating glucocorticoid levels has been recognized as a major internal synchronizer of the circadian system. The present review examines the scientific foundation of these novel advances and their implications for health and disease prevention and treatment.

Pain control by melatonin: Physiological and pharmacological effects

Pain and anxiety are the most common neurological responses to many harmful or noxious stimuli and their management clinically is often challenging. Many of the frequently used morphine-based drugs, non-steroid anti-inflammatory drugs and acetaminophen, while efficient for treating pain, lead to patients suffering from several unwanted side effects. Melatonin, produced from the pineal body is a hormone of darkness, is involved in the control of circadian rhythms, and exerts a number of pharmacological effects. Melatonin mediates its actions through MT1/MT2 melatonin receptors on the cell membrane and also through RZR/ROR nuclear orphan receptors. Chronic pain syndromes are often associated with the desynchronization of circadian and biological rhythms, which also cause disturbances in the sleep-wake cycle. Melatonin-mediated analgesic effects seem to involve β-endorphins, GABA receptor, opioid receptors and the nitric oxide-arginine pathway. The effectiveness of melatonin as an analgesic and anxiolytic agent has been demonstrated in various animal models of pain and this led to the use of melatonin clinically in different pathological conditions and also in patients undergoing surgery. Melatonin was found to be effective in many of these cases as an anxiolytic and analgesic agent, indicating its clinical application.

Circadian variations in clinical symptoms and concentrations of inflammatory cytokines, melatonin, and cortisol in polymyalgia rheumatica before and during prednisolone treatment: a controlled, observational, clinical experimental study

BACKGROUND

In contrast to rheumatoid arthritis (RA), no systematic investigation of diurnal variation has been carried out in polymyalgia rheumatica (PMR). The aim of the study was to provide the often-requested documentation of the 24-h time course of clinical symptoms in PMR and relate them to concentrations during the day of melatonin, inflammatory cytokines, and cortisol. Furthermore, the effects of 14 days of prednisolone treatment were studied.

METHODS

Ten glucocorticoid-naive patients newly diagnosed with PMR and seven non-PMR control subjects were studied for 24 h before treatment and during the 14th day of treatment with 20 mg/day of prednisolone. Global pain and generalized muscle stiffness were monitored by using visual analogue scales, and blood was drawn repeatedly.

RESULTS

In untreated patients, pain and stiffness peaked in the early morning, showing a plateau between 04:00 and 08:00, and then declined to a nadir at 16:00 (2P < 0.05). Plasma concentrations of interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)-α, IL-1β, and IL-4 varied with time in both groups (2P < 0.05) and peaked between 04:00 and 08:00. Furthermore, except for IL-1β, concentrations of these cytokines and of IL-10 were higher throughout the 24-h observation period in patients than in control subjects (2P < 0.05). Also, melatonin and cortisol were consistently higher in patients (2P < 0.05) and varied with time (2P < 0.05), peaking around 02:00 and 08:00, respectively. In patients, prednisolone abolished symptoms, normalized C-reactive protein, and reduced melatonin, IL-6, IL-8, and TNF-α concentrations (2P < 0.05), while IL-10 increased between 10:00 and 14:00.

CONCLUSIONS

In PMR, key symptoms show diurnal variation. Furthermore, in PMR, concentrations of melatonin, several pro- and anti-inflammatory cytokines, and cortisol are increased throughout the day and show diurnal variation, as also seen in healthy subjects. The time courses and the inhibitory effects of prednisolone indicate that in PMR, as proposed for RA, melatonin stimulates cytokine production, which in turn accounts at least partly for the symptoms. Furthermore, overall, cortisol may downregulate cytokine production and symptoms. Stimulation of IL-10 secretion may participate in the anti-inflammatory effects of prednisolone. These findings support use of chronotherapy in PMR and encourage study of circadian variations in other inflammatory autoimmune diseases.

Melatonin in Chronic Pain Syndromes

Melatonin is a neurohormone secreted by epiphysis and extrapineal structures. It performs several functions including chronobiotic, antioxidant, oncostatic, immune modulating, normothermal, and anxiolytic functions. Melatonin affects the cardiovascular system and gastrointestinal tract, participates in reproduction and metabolism, and body mass regulation. Moreover, recent studies have demonstrated melatonin efficacy in relation to pain syndromes. The present paper reviews the studies on melatonin use in fibromyalgia, headaches, irritable bowel syndrome, chronic back pain, and rheumatoid arthritis. The paper discusses the possible mechanisms of melatonin analgesic properties. On one hand, circadian rhythms normalization results in sleep improvement, which is inevitably disordered in chronic pain syndromes, and activation of melatonin adaptive capabilities. On the other hand, there is evidence of melatonin-independent analgesic effect involving melatonin receptors and several neurotransmitter systems.

Thalamic mechanisms underlying alpha-delta sleep with implications for fibromyalgia

Alpha-delta sleep is the abnormal intrusion of alpha activity (8- to 13-Hz oscillations) into the delta activity (1- to 4-Hz oscillations) that defines slow-wave sleep. Alpha-delta sleep is especially prevalent in fibromyalgia patients, and there is evidence suggesting that the irregularities in the sleep of these patients may cause the muscle and tissue pain that characterizes the disorder. We constructed a biophysically realistic mathematical model of alpha-delta sleep. Imaging studies in fibromyalgia patients suggesting altered levels of activity in the thalamus motivated a thalamic model as the source of alpha activity. Since sodium oxybate helps to alleviate the symptoms of fibromyalgia and reduces the amount of alpha-delta sleep in fibromyalgia patients, we examined how changes in the molecular targets of sodium oxybate affected alpha-delta activity in our circuit. Our model shows how alterations in GABAB currents and two thalamic currents, Ih (a hyperpolarization-activated current) and a potassium leak current, transform a circuit that normally produces delta oscillations into one that produces alpha-delta activity. Our findings suggest that drugs that reduce Ih conductances and/or increase potassium conductances, without necessarily increasing GABAB conductances, might be sufficient to restore delta sleep. Furthermore, they suggest that delta sleep might be restored by drugs that preferentially target these currents in the thalamus; such drugs might have fewer side effects than drugs that act systemically.

Quantifying Pituitary-Adrenal Dynamics and Deconvolution of Concurrent Cortisol and Adrenocorticotropic Hormone Data by Compressed Sensing

Pulsatile release of cortisol from the adrenal glands is governed by pulsatile release of adrenocorticotropic hormone (ACTH) from the anterior pituitary. In return, cortisol has a negative feedback effect on ACTH release. Simultaneous recording of ACTH and cortisol is not typical, and determining the number, timing, and amplitudes of pulsatile events from simultaneously recorded data is challenging because of several factors: 1) stimulator ACTH pulse activity, 2) kinematics of ACTH and cortisol, 3) the sampling interval, and 4) the measurement error. We model ACTH and cortisol secretion simultaneously using a linear differential equations model with Gaussian errors and sparse pulsatile events as inputs to the model. We propose a novel framework for recovering pulses and parameters underlying the interactions between ACTH and cortisol. We recover the timing and amplitudes of pulses using compressed sensing and employ generalized cross validation for determining the number of pulses. We analyze serum ACTH and cortisol levels sampled at 10-min intervals over 24 h from ten healthy women. We recover physiologically plausible timing and amplitudes for these pulses and model the feedback effect of cortisol. We recover 15 to 18 pulses over 24 h, which is highly consistent with the results of another cortisol data analysis approach. Modeling the interactions between ACTH and cortisol allows for accurate quantification of pulsatile events, and normal and pathological states. This could lay the basis for a more physiologically-based approach for administering cortisol therapeutically. The proposed approach can be adapted to deconvolve other pairs of hormones with similar interactions.

Biological time series analysis using a context free language: applicability to pulsatile hormone data

We present a novel approach for analyzing biological time-series data using a context-free language (CFL) representation that allows the extraction and quantification of important features from the time-series. This representation results in Hierarchically AdaPtive (HAP) analysis, a suite of multiple complementary techniques that enable rapid analysis of data and does not require the user to set parameters. HAP analysis generates hierarchically organized parameter distributions that allow multi-scale components of the time-series to be quantified and includes a data analysis pipeline that applies recursive analyses to generate hierarchically organized results that extend traditional outcome measures such as pharmacokinetics and inter-pulse interval. Pulsicons, a novel text-based time-series representation also derived from the CFL approach, are introduced as an objective qualitative comparison nomenclature. We apply HAP to the analysis of 24 hours of frequently sampled pulsatile cortisol hormone data, which has known analysis challenges, from 14 healthy women. HAP analysis generated results in seconds and produced dozens of figures for each participant. The results quantify the observed qualitative features of cortisol data as a series of pulse clusters, each consisting of one or more embedded pulses, and identify two ultradian phenotypes in this dataset. HAP analysis is designed to be robust to individual differences and to missing data and may be applied to other pulsatile hormones. Future work can extend HAP analysis to other time-series data types, including oscillatory and other periodic physiological signals.

Reduced hypothalamic-pituitary-adrenal axis activity in chronic multi-site musculoskeletal pain: partly masked by depressive and anxiety disorders

BACKGROUND

Studies on hypothalamic-pituitary-adrenal axis (HPA-axis) function amongst patients with chronic pain show equivocal results and well-controlled cohort studies are rare in this field. The goal of our study was to examine whether HPA-axis dysfunction is associated with the presence and the severity of chronic multi-site musculoskeletal pain.

METHODS

Data are from the Netherlands Study of Depression and Anxiety including 1125 subjects with and without lifetime depressive and anxiety disorders. The Chronic Pain Grade questionnaire was used to determine the presence and severity of chronic multi-site musculoskeletal pain. Subjects were categorized into a chronic multi-site musculoskeletal pain group (n = 471) and a control group (n = 654). Salivary cortisol samples were collected to assess HPA-axis function (awakening level, 1-h awakening response, evening level, diurnal slope and post-dexamethasone level).

RESULTS

In comparison with the control group, subjects with chronic multi-site musculoskeletal pain showed significantly lower cortisol level at awakening, lower evening level and a blunted diurnal slope. Lower cortisol level at awakening and a blunted diurnal slope appeared to be restricted to those without depressive and/or anxiety disorders, who also showed a lower 1-h awakening response.

CONCLUSIONS

Our results suggest hypocortisolemia in chronic multi-site musculoskeletal pain. However, if chronic pain is accompanied by a depressive or anxiety disorder, typically related to hypercortisolemia, the association between cortisol levels and chronic multi-site musculoskeletal pain appears to be partly masked. Future studies should take psychopathology into account when examining HPA-axis function in chronic pain.

Deconvolution of serum cortisol levels by using compressed sensing

The pulsatile release of cortisol from the adrenal glands is controlled by a hierarchical system that involves corticotropin releasing hormone (CRH) from the hypothalamus, adrenocorticotropin hormone (ACTH) from the pituitary, and cortisol from the adrenal glands. Determining the number, timing, and amplitude of the cortisol secretory events and recovering the infusion and clearance rates from serial measurements of serum cortisol levels is a challenging problem. Despite many years of work on this problem, a complete satisfactory solution has been elusive. We formulate this question as a non-convex optimization problem, and solve it using a coordinate descent algorithm that has a principled combination of (i) compressed sensing for recovering the amplitude and timing of the secretory events, and (ii) generalized cross validation for choosing the regularization parameter. Using only the observed serum cortisol levels, we model cortisol secretion from the adrenal glands using a second-order linear differential equation with pulsatile inputs that represent cortisol pulses released in response to pulses of ACTH. Using our algorithm and the assumption that the number of pulses is between 15 to 22 pulses over 24 hours, we successfully deconvolve both simulated datasets and actual 24-hr serum cortisol datasets sampled every 10 minutes from 10 healthy women. Assuming a one-minute resolution for the secretory events, we obtain physiologically plausible timings and amplitudes of each cortisol secretory event with R² above 0.92. Identification of the amplitude and timing of pulsatile hormone release allows (i) quantifying of normal and abnormal secretion patterns towards the goal of understanding pathological neuroendocrine states, and (ii) potentially designing optimal approaches for treating hormonal disorders.

Urinary albumin, protein excretion and circadian blood pressure in patients with fibromyalgia

Recent evidence suggests that patients with fibromyalgia (FM) have increased oxidative stress, inflammation, endothelial dysfunction and autonomic dysfunction. These factors are also shown to be responsible for increased urinary albumin and protein excretion and deranged circadian blood pressure (BP). However, no study has examined the 24-h urinary albumin excretion (UAE), 24-h urinary protein excretion (UPE) and 24-h ambulatory BP measurements in FM patients. The sociodemographic, laboratory parameters, depressive symptoms, sleep problems and 24-h ambulatory BPs were measured for all patients. Diagnosis of FM was based on the criteria for the classification of FM by the American College of Rheumatology. After diagnosis of FM, these patients underwent to complete the Fibromyalgia Impact Questionnaire (FIQ). In total, 30 patients with FM and 61 patients without FM were included. Among FM patients, the average number of tender points was 13.1 ± 1.57 and the mean FIQ score was 57.9 ± 8.86. The number of tender points did not show any correlation with office and ambulatory BPs. There were also no correlations between the number of tender points, UPE and UAE. The stepwise linear regression did not show any relation between UPE and FM. However, 24-h UAE was independently correlated with office systolic BP (P 0.008) and the presence of FM (P 0.045). The logistic regression analysis revealed no association between FM and non-dipping status. We suggest that circadian blood pressure and UPE are not independently associated with FM. However, UAE was related with the presence of FM. Studies are needed to confirm our findings and to highlight pathophysiologic mechanisms.

Circadian rhythm of serum cortisol in female patients with fibromyalgia syndrome

Fibromyalgia syndrome (FMS) patients have disturbed sleep patterns which may lead to altered circadian rhythm in serum cortisol secretion. The aim of this study was to assess circadian changes, if any, in serum cortisol levels in female patients with FMS. Cortisol levels were estimated every 6 h during 24 h period; in 40 female patients satisfying ACR criteria for FMS (Age 36.4 ± 9.9), and 40 healthy females without FMS (Age 33.8 ± 11.1). A significant difference in the night time serum cortisol level was observed among the patients and control groups (patients, 12.9 ± 9.7 controls 5.8 ± 3.0; p < 0.01). However, no significant difference was found in serum cortisol levels in patients and control groups in the morning (patients, 28.4 ± 13.2 controls, 27.6 ± 14.5; p > 0.05), afternoon (patients, 14.4 ± 5.6 controls, 14.0 ± 6.6; p > 0.05) and evening hours (patients, 10.9 ± 5.8 controls, 8.9 ± 3.6; p > 0.05). It could be concluded that there is an abnormality in circadian secretion of cortisol in female FMS patients.

Fibromyalgia syndrome and chronotype: late chronotypes are more affected

Sleep has strong links to the symptomology of fibromyalgia syndrome (FMS), a diffuse musculoskeletal pain disorder. Information about the involvement of the circadian clock is, however, sparse. In this study, 1548 individuals with FMS completed an online survey containing questions on demographics, stimulant consumption, sleep quality, well-being and subjective pain, chronotype (assessed by the Munich ChronoType Questionnaire, MCTQ), and FMS impact. Chronotype (expressed as the mid-sleep-point on free days, corrected for sleep deficit on workdays, MSF(sc)) significantly correlated with stress-ratings, so-called "memory failures in everyday life," fatigue, FMS impact, and depression but not with anxiety. When chronotypes were categorized into 3 groups (early, intermediate, late), significant group differences were found for sum scores of perceived stress, memory failures in everyday life, fatigue, FMS impact, and depression but not anxiety, with late chronotypes being more affected than early chronotypes. Sleepiness ratings were highest in early chronotypes. Challenges of sleep quality and subjective pain were significantly increased in both early and late chronotypes. The results show that according to their reports, late chronotypes are more affected by fibromyalgia.

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.

[Etiology and pathophysiology of fibromyalgia syndrome and chronic widespread pain]

OBJECTIVE

To write a systematic review on the etiology and pathophysiology of the fibromyalgia syndrome (FMS) and of chronic widespread pain (CWP).

METHODS

An interdisciplinary level-3 guideline (i.e. systematic literature search and assessment, logic analysis, formal consensus procedure) for the diagnosis and therapy of FMS was created in cooperation with 10 medical and psychological societies and 2 patient self-help organizations. A literature search was performed covering all available review articles on the etiology and pathophysiology of FMS and CWP using the Cochrane Collaboration Reviews (1993-12/2006), Medline (1980-2006), PsychInfo (1966-12/2006), and Scopus (1980-12/2006). For the assignment of evidence classes the system of the Oxford Centre for Evidence-Based Medicine was applied. Consensus was achieved by a multi-step nominal group procedure.

RESULTS

FMS aggregates in families (evidence level 2c). Physical and psychological stress at the workplace are risk factors for the development of CWP and FMS. Affective disorders are risk factors for the development and maintenance of FMS. Operant learning mechanisms and sensitization are risk factors for the chronification of FMS (evidence levels 2b). Several factors are associated with the pathophysiology of FMS, but the causal relationship is unclear. This includes alterations of central pain pathways, hyporeactivity of the hypothalamus-pituitary-adrenal axis, increased systemic pro-inflammatory and reduced anti-inflammatory cytokine profiles and disturbances in the dopaminergic and serotonergic systems.

CONCLUSIONS

FMS is the common final product of various etiological factors and pathophysiological mechanisms.

Melatonin therapy in fibromyalgia

Fibromyalgia (FM) is a painful syndrome that is more common in women than in men. Whether FM has an organic basis or whether it is psychosomatic is debated. Of the numerous treatments that have been tried, rarely have any been completely effective in relieving the pain of FM. Preliminary evidence indicates that melatonin, a molecule that is endogenously produced and is available as an over-the-counter supplement, may be effective in treating the pain associated with this syndrome. Although melatonin is commonly known as a sleep aid (sleep/wake problems are common in FM sufferers), it has a variety of other beneficial effects that may account for its potential benefits in the treatment of FM.

Fibromyalgia: the gastrointestinal link

Patients with fibromyalgia (FM) frequently have gastrointestinal symptoms and signs. This article critically reviews the available literature and concludes the following: evidence that inflammatory bowel disease is associated with FM is contradictory, but should be looked for in patients taking concomitant steroids; patients diagnosed with celiac disease often have a history of FM or irritable bowel syndrome (IBS) that may or may not be present; reflux, nonulcer dyspepsia, and noncardiac chest pain are common in FM patients; medications used to manage pain, inflammation, and gastrointestinal complaints confound the management of FM; and IBS affects smooth muscles and the parasympathetic nervous system, while FM patients have complaints of striated muscles and dysfunction of the sympathetic nervous system. Of those patients with FM, 30% to 70% have concurrent IBS. Small intestinal bacterial overgrowth is associated with hyperalgesia and IBS-like complaints, is common in FM, and responds transiently to antimicrobial therapy.

Neuroendocrine abnormalities in fibromyalgia

Fibromyalgia is a disorder of unknown etiology characterized by chronic, widespread musculoskeletal pain and symptoms such as fatigue, poor sleep, gastrointestinal complaints, and psychologic problems that are similar to those experienced by patients with hormone deficiencies. This review summarizes the available data on the neuroendocrine function in fibromyalgia, including data on hormone secretion, circadian phase, and autonomic nervous system function. Studies suggest that there may be lower activity of a number of hypothalamic-pituitary-peripheral gland axes and altered autonomic nervous system function in patients with fibromyalgia. These reductions in activity are mild to moderate and do not result from alterations in circadian rhythms. The reduced hormonal and autonomic responses appear to reflect an impairment in the hypothalamic or central nervous system response to stimuli rather than a primary defect at the level of the pituitary gland or the peripheral glands. A combination of multiple, mild impaired responses may lead to more profound physiologic and clinical consequences as compared with a defect in only one system, and could contribute to the symptoms of fibromyalgia.