Psychophysiological responses in patients with fibromyalgia syndrome

The relationship between metacognition, anger, and pain intensity among fibromyalgia patients: a serial mediation model

Fibromyalgia is a burdensome pain causing patients a very negative emotional state that can worsen their clinical profile, perceived disability, and treatment outcomes. In particular, anger can negatively affect pain and patient adjustment to the disease. Recent studies suggest that metacognitions and anger rumination can negatively affect anger, which in turn can amplify the intensity of pain. This study aims to investigate whether anger rumination and state anger serially mediate the relationship between metacognitions and the intensity of pain. The study included 446 subjects who: declared having received a fibromyalgia diagnosis by a rheumatologist/pain physician; completed measures of metacognitions, anger rumination, state-anger, and pain intensity. The serial mediation analysis was conducted using Hayes' PROCESS macro (Model 6). Negative beliefs about worry and beliefs about the need to control thoughts indirectly influenced the intensity of pain through two significant mediating pathways: state-anger and anger rumination to state-anger. Cognitive self-consciousness affected pain intensity directly (β = .11, p < .05) and indirectly through two significant mediating pathways: state-anger and anger rumination to state-anger. This study highlights the role of serial mediation of anger rumination and state-anger in the relationship between metacognitions and pain intensity in the field of fibromyalgia. Our work introduces new targets for anger management interventions for patients with fibromyalgia. Such interventions could be effectively addressed with a metacognitive approach considering its specific focus on dysfunctional metacognitive beliefs and repetitive negative thinking.

The autonomic and nociceptive response to acute experimental stress is impaired in people with knee osteoarthritis: A preliminary study

Objective

Alterations in autonomic function are evident in some chronic pain conditions but have not been thoroughly examined in people with osteoarthritis (OA). The study aimed to examine resting autonomic nervous system (ANS) function in people with knee OA, and the response of the autonomic and nociceptive systems to acute stress.

Methods

A preliminary cross-sectional study was undertaken involving people with knee OA (n = 14), fibromyalgia (n = 13), and pain-free controls (n = 15). The sympathetic and parasympathetic components of the ANS were assessed through measures of pre-ejection period (PEP), skin conductance level (SCL), and high frequency heart rate variability (HF HRV). The nociceptive system was assessed through pain ratings associated with a tonic heat pain stimulus. In separate sessions, ANS and heat pain measures were assessed at rest and in response to nociceptive and mental arithmetic stressors.

Results

The knee OA group showed reduced HF HRV at rest and reduced modulation in response to stress. Resting PEP and SCL were normal in the knee OA group but PEP modulation was impaired in both chronic pain groups during nociceptive stress. The expected reduction in tonic heat pain ratings in response to stress was lacking in the knee OA and FM groups.

Conclusion

Preliminary evidence shows impaired parasympathetic nervous system function at rest and in response to nociceptive and mental stress in people with knee OA, with some evidence of altered sympathetic nervous system function. Impaired ANS function could contribute to ongoing pain experienced, and interventions that target ANS function could be beneficial.

Neural indices of multimodal sensory and autonomic hyperexcitability in fibromyalgia

Fibromyalgia (FM) is characterized by chronic widespread musculoskeletal pain and psychological distress. Research suggests people with FM experience increased somatosensory sensitization which generalizes to other sensory modalities and may indicate neural hyperexcitability. However, the available evidence is limited, and studies including measures of neural responsivity across sensory domains and both central and peripheral aspects of the neuraxis are lacking. Thirty-nine participants (51.5 ± 13.6 years of age) with no history of neurological disorders, psychosis, visual, auditory, or learning deficits, were recruited for this study. People with FM (N = 19) and control participants (CNT, N = 20) did not differ on demographic variables and cognitive capacity. Participants completed a task that combined innocuous auditory stimuli with electrocutaneous stimulation (ECS), delivered at individually-selected levels that were uncomfortable but not painful. Event-related potentials (ERPs) and electrodermal activity were analyzed to examine the central and sympathetic indices of neural responsivity. FM participants reported greater sensitivity to ECS and auditory stimulation, as well as higher levels of depression, anxiety, ADHD, and an array of pain-related experiences than CNT. In response to ECS, the P50 deflection was greater in FM than CNT participants, reflecting early somatosensory hyperexcitability. The P50 amplitude was positively correlated with the FM profile factor obtained with a principal component analysis. The N100 to innocuous tones and sympathetic reactivity to ECS were greater in FM participants, except in the subgroup treated with gabapentinoids, which aligns with previous evidence of symptomatic improvement with GABA-mimetic medications. These results support the principal tenet of generalized neural hyperexcitability in FM and provide preliminary mechanistic insight into the impact of GABA-mimetic pharmacological therapy on ameliorating the neural excitation dominance.

"INTEGRO INTEGRated Psychotherapeutic InterventiOn" on the Management of Chronic Pain in Patients with Fibromyalgia: The Role of the Therapeutic Relationship

Fibromyalgia (FM) is a chronic disease characterized by a heterogeneous set of physical and psychological conditions. The chronic experience of disability felt by patients and the impact on quality of life (QoL) of the disease may worsen the cognitive reappraisal ability and contribute to maintaining an altered pain modulation mechanism. This paper presents the study protocol of an INTEGRated psychotherapeutic interventiOn on the management of chronic pain in patients with fibromyalgia (INTEGRO). The aim of the study is to investigate the efficacy of an integrated psychotherapeutic intervention focused on pain management on QoL and pain perception, in a pilot sample of 45 FM patients with idiopathic chronic pain. The contribution of perceived therapeutic relationship (alliance) and physiological attunement, in both the patient and therapist, will be considered as possible mediators of intervention efficacy. Attachment dimensions, traumatic experiences, difficulties in emotion regulation, mindfulness attitude and psychophysiological profile will also be considered as covariates. The objectives are to evaluate longitudinally if patients will experience an increase in QoL perception (primary endpoint), pain-managing self-efficacy and emotion-regulation abilities as well as a reduction in pain intensity (secondary endpoints), considering the mediating role of perceived therapeutic alliance and physiological attunement in both the patient and therapist.

The autonomic and nociceptive response to acute exercise is impaired in people with knee osteoarthritis

Objectives

An acute bout of exercise typically leads to short term exercise induced hypoalgesia (EIH), but this response is more variable in many chronic pain populations, including knee osteoarthritis (OA) and fibromyalgia (FM). There is evidence of autonomic nervous system (ANS) dysfunction in some chronic pain populations that may contribute to impaired EIH, but this has not been investigated in people with knee OA. The aim of this study was to assess the acute effects of isometric exercise on the nociceptive and autonomic nervous systems in people with knee OA and FM, compared to pain-free controls.

Methods

A cross-sectional study was undertaken with 14 people with knee OA, 13 people with FM, and 15 pain free controls. Across two experimental sessions, baseline recordings and the response of the nociceptive and autonomic nervous systems to a 5-min submaximal isometric contraction of the quadriceps muscle was assessed. The nociceptive system was assessed using pressure pain thresholds at the knee and forearm. The ANS was assessed using high frequency heart rate variability, cardiac pre-ejection period, and electrodermal activity. Outcome measures were obtained before and during (ANS) or immediately after (nociceptive) the acute bout of exercise.

Results

Submaximal isometric exercise led to EIH in the control group. EIH was absent in both chronic pain groups. Both chronic pain groups showed lower vagal activity at rest. Furthermore, people with knee OA demonstrated reduced vagal withdrawal in response to acute isometric exercise compared to controls. Sympathetic reactivity was similar across groups.

Discussion

The findings of reduced tonic vagal activity and reduced autonomic modulation in response to isometric exercise raise the potential of a blunted ability to adapt to acute exercise stress and modulate nociception in people with knee OA. The impairment of EIH in knee OA may, in part, be due to ANS dysfunction.

Heart rate variability responses to cognitive stress in fibromyalgia are characterised by inadequate autonomous system stress responses: a clinical trial

Fibromyalgia (FM) is associated with sympathetically dominant dysautonomia, but the connection between dysautonomia and FM symptoms is unclear. Dysautonomia can be analysed with heart rate variability (HRV) and it has been proposed that FM patients comprise subgroups with differing profiles of symptom severity. In our study, 51 female FM patients aged 18 to 65 years and 31 age-matched healthy female controls followed a 20-min protocol of alternating relaxation and cognitive stress (mental arithmetic). Heart rates and electrocardiograms were registered. The HRV measures of heart rate (HR), mean interval between heart beats (RR_mean), root mean squared interval differences of successive beats (RMSSD), and the standard deviation of intervals between normal heart beats (SDNN) were analysed with generalized linear modelling. Features in HRV reactivity which differed between FM patients and controls were used to cluster the FM patients and cluster characteristics were analysed. FM patients had higher baseline HR (72.3 [SD 12.7] vs 64.5 [7.80], p < 0.001) and lower RR_mean (0.844 [0.134] vs 0.934 [0.118], p = 0.002), compared with controls. They also reacted to repeated cognitive stress with an attenuated rise in HR (- 4.41 [95% CI - 7.88 to - 0.93], p = 0.013) and attenuated decrease of RR_mean (0.06 [95 CI 0.03 to 0.09], p < 0.001), compared with controls. Clustering of FM patients by HRV reactivity resulted in three clusters characterised by (1) normal levels of HRV and HRV reactivity with low levels of depressive mood and anxiety, (2) reduced levels of HRV and impaired HRV reactivity with increased levels of depressive mood and high levels of anxiety, and (3) lowest HRV and most impaired HRV reactivity with the highest scores for depressive mood and anxiety. Our results show that FM patients have lower HRV than healthy controls and their autonomous reactions to cognitive stress are attenuated. Dysautonomia in FM associates with mood disturbance. Trial registration ClinicalTrials.gov (NCT03300635). Registered October 3 2017-Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03300635 .

The Role of Depressive Disorders in Autonomic Cardiovascular Dysregulation in Fibromyalgia

OBJECTIVE

Previous research revealed aberrances in autonomic cardiovascular regulation in fibromyalgia, which may be relevant to symptoms genesis and the increased risk of cardiovascular disorders in individuals with fibromyalgia. This study investigated the role of comorbid depression in autonomic cardiovascular dysregulations in fibromyalgia.

METHODS

Cardiovascular recordings were obtained in 53 participants with fibromyalgia who also had depression ( n = 27), in participants with fibromyalgia without depression ( n = 26), and in 29 healthy controls, at rest and during a cold pressor test and an arithmetic task. Assessed parameters included interbeat interval, blood pressure, heart rate variability, baroreflex sensitivity, stroke volume, preejection period, left ventricular ejection time, Heather index, and total peripheral resistance.

RESULTS

Participants with both fibromyalgia and depression displayed lower tonic interbeat interval, baroreflex sensitivity, and heart rate variability compared with participants with fibromyalgia without depression and controls ( p values < .012, d values = 0.71-1.06). Participants with fibromyalgia but without depression did not differ from controls in these variables. Moreover, participants with fibromyalgia who also had depression, but not those without depression, exhibited lower Heather index, stroke volume, and left ventricular ejection time compared with controls ( p values < .013, d values = 0.62-0.78). No group differences arose for preejection period or total peripheral resistance. Stress reactivity was reduced in participants with fibromyalgia, independently of depression, for diastolic blood pressure, interbeat interval, left ventricular ejection time, and heart rate variability, than in controls.

CONCLUSIONS

The role of depression in the autonomic dysregulation in fibromyalgia involves chronotropic cardiac control rather than adrenergic influences on contractility and vascular tone. Blunted cardiovascular reactivity may be ascribable to pathological factors inherent to fibromyalgia. These results underline the importance of diagnostics and treatment of comorbid depressive disorders in the management of fibromyalgia.

Druggable Targets and Compounds with Both Antinociceptive and Antipruritic Effects

Pain and itch are both important manifestations of various disorders, such as herpes zoster, atopic dermatitis, and psoriasis. Growing evidence suggests that both sensations have shared mediators, overlapping neural circuitry, and similarities in sensitization processes. In fact, pain and itch coexist in some disorders. Determining pharmaceutical agents and targets for treating pain and itch concurrently is of scientific and clinical relevance. Here we review the neurobiology of pain and itch and discuss the pharmaceutical targets as well as novel compounds effective for the concurrent treatment of these sensations.

A Systematic Review and Meta-Analysis of the Prevalence of Small Fibre Impairment in Patients with Fibromyalgia

Converging evidence shows that patients with fibromyalgia syndrome have signs of small fibre impairment, possibly leading to pain and autonomic symptoms, with a frequency that has not yet been systematically evaluated. To fill this gap, our review aims to define the frequency of somatic and autonomic small fibre damage in patients with fibromyalgia syndrome, as assessed by objective small fibre-related testing. We found 360 articles on somatic and autonomic small fibre assessment in patients with fibromyalgia. Out of the 88 articles assessed for eligibility, 20 were included in the meta-analysis, involving 903 patients with fibromyalgia. The estimated prevalence of somatic small fibre impairment, as assessed with skin biopsy, corneal confocal microscopy, and microneurography, was 49% (95% confidence interval (CI): 39–60%, I² = 89%), whereas the estimated prevalence of autonomic small fibre impairment, as assessed with heart rate variability, sympathetic skin response, skin conductance, and tilt testing, was 45% (95% CI: 25–65%, I² = 91%). Our study shows that a considerable proportion of patients with fibromyalgia have somatic and autonomic small fibre impairment, as assessed by extensive small fibre-related testing. Nevertheless, the heterogeneity and inconsistencies across studies challenge the exact role of small fibre impairment in fibromyalgia symptoms.

Physical Therapy for Muscle Tension Dysphonia with Cervicalgia

OBJECTIVES

This study investigated the effectiveness of a specialized manual physical therapy (PT) program at improving voice among patients diagnosed with concomitant muscle tension dysphonia (MTD) and cervicalgia at a tertiary care voice center.

MATERIALS AND METHODS

Cervicalgia was determined by palpation of the anterior neck. Both voice therapy (VT) and PT was recommended for all patients diagnosed with MTD and cervicalgia. PT included full-body manual physical therapy with myofascial release. Patients underwent: 1) VT alone, 2) concurrent PT and VT (PT with VT), 3) PT alone, 4) VT, but did not have PT ordered by treating clinician (VT without PT order) or 5) VT followed by PT (VT then PT). The pairwise difference in post-Voice Handicap Index-10 (VHI-10) controlling for baseline variables was calculated with a linear regression model.

RESULTS

178 patients met criteria. All groups showed improvement with treatment. The covariate-adjusted differences in mean post-VHI-10 improvement comparing the VT alone group as a reference were as follows: PT with VT 9.95 (95% confidence interval 7.70, 12.20); PT alone 8.31 (6.16, 10.45); VT without PT order 8.51 (5.55, 11.47); VT then PT 5.47 (2.51, 8.42).

CONCLUSION

Among patients diagnosed with MTD with cervicalgia, treatment with a specialized PT program was associated with improvement in VHI-10 scores regardless of whether they had VT. While VT is the standard of care for MTD, PT may also offer benefit for MTD patients with cervicalgia.

Blunted Pain Modulation Response to Induced Stress in Women with Fibromyalgia with and without Posttraumatic Stress Disorder Comorbidity: New Evidence of Hypo-Reactivity to Stress in Fibromyalgia?

There is evidence regarding the presence of alterations in both the stress response and the endogenous pain modulation systems of people with fibromyalgia (FM). However, research on pain modulation under induced stress on FM patients is scarce and contradictory. The present study analyzes stress-induced changes in pain and intolerance thresholds among FM patients, examining the possible existence of differences linked to PTSD comorbidity and gaining insights into the role of cardiovascular reactivity. Eighteen women diagnosed with FM and comorbid PTSD (FM + PTSD), 18 women diagnosed with FM and no PTSD (FM-PTSD), and 38 healthy women (HC) were exposed to the Social Stress Test task. Pressure pain thresholds and intolerance thresholds were measured before and during stress induction, and after a recovery period, while systolic blood pressure and heart rate were simultaneously recorded. Overall, while pain thresholds decreased during stress and recovery for HC, no significant changes were observed for women with FM. The intolerance threshold decreased for HC during stress, but was maintained at basal level during recovery. FM-PTSD women exhibited a delayed response, with a drop at recovery. For FM + PTSD, tolerance levels remained unchanged. In addition, cardiovascular reactivity did not seem to explain these results. This performance of the pain modulation system seems to follow the same pattern of hypoactive responsiveness under stressors that has previously been observed in FM patients on the autonomic and neuroendocrine axes. Such a hypoactive pattern may involve a non-adaptive response that may contribute to the development and maintenance of chronic pain.

The cardiac, vasomotor, and myocardial branches of the baroreflex in fibromyalgia: Associations with pain, affective impairments, sleep problems, and fatigue

This study investigated the cardiac, vasomotor, and myocardial branches of the baroreflex in fibromyalgia using the spontaneous sequence method. Systolic blood pressure (SBP), interbeat interval (IBI), stroke volume (SV), pre-ejection period (PEP), and total peripheral resistance (TPR) were continuously recorded in 40 fibromyalgia patients and 30 healthy individuals during a cold pressor test and a mental arithmetic task. Sequences of covariation between SBP and IBI (cardiac branch), SV and PEP (myocardial branch), and TPR (vasomotor branch) were identified. Baroreflex sensitivity (BRS) was represented by the slope of the regression line between values in the sequences; baroreflex effectiveness (BEI) was indexed by the proportion of progressive SBP changes that elicited reflex responses. Patients exhibited lower BRS in the three branches, lower BEI in the cardiac and vasomotor branches, and reduced reactivity in cardiac BRS and BEI, SBP, IBI, SV, and PEP. Moreover, BRS and BEI were inversely related to clinical pain, cold pressor pain, depression, trait anxiety, sleep problems, and fatigue. Reduced function of the three baroreflex branches implies diminished resources for autonomic inotropic, chronotropic, and vascular regulation in fibromyalgia. Blunted stress reactivity indicates a limited capacity for autonomic cardiovascular adjustment to situational requirements. The associations of BRS and BEI with pain perception may reflect the antinociceptive effects arising from baroreceptor afferents, where reduced baroreflex function may contribute to the hyperalgesia characterizing fibromyalgia. The associations with affective impairments, sleep problems, and fatigue suggest that baroreflex dysfunctions are also involved in the secondary symptoms of the disorder.

Muscle activity and acute stress in fibromyalgia

Background

Fibromyalgia (FM) patients are likely to differ from healthy controls in muscle activity and in reactivity to experimental stress.

Methods

We compared psychophysiological reactivity to cognitive stress between 51 female FM patients aged 18 to 65 years and 31 age- and sex-matched healthy controls. They underwent a 20-minute protocol consisting of three phases of relaxation and two phases of cognitive stress. We recorded surface electromyography normalized to maximum voluntary muscle contraction (%EMG), the percentage of time with no muscle activity (EMG rest time), and subjective pain and stress intensities. We compared group reactivity using linear modelling and adjusted for psychological and life-style factors.

Results

The FM patients had a significantly higher mean %EMG (2.2 % vs. 1.0 %, p < 0.001), pain intensity (3.6 vs. 0.2, p < 0.001), and perceived stress (3.5 vs. 1.4, p < 0.001) and lower mean EMG rest time (26.7 % vs. 47.2 %, p < 0.001). In the FM patients, compared with controls, the pain intensity increased more during the second stress phase (0.71, p = 0.028), and the %EMG decreased more during the final relaxation phase (-0.29, p = 0.036). Within the FM patients, higher BMI predicted higher %EMG but lower stress. Leisure time physical activity predicted lower %EMG and stress and higher EMG rest time. Higher perceived stress predicted lower EMG rest time, and higher trait anxiety predicted higher pain and stress overall.

Conclusions

Our results suggest that repeated cognitive stress increases pain intensity in FM patients. FM patients also had higher resting muscle activity, but their muscle activity did not increase with pain. Management of stress and anxiety might help control FM flare-ups.

Trial registration

Retrospectively registered on ClinicalTrials.gov (NCT03300635).

Reduced activity, reactivity and functionality of the sympathetic nervous system in fibromyalgia: An electrodermal study

Alterations in autonomic activity are well established in fibromyalgia syndrome (FMS). Previous studies found reduced parasympathetic activity and sympathetic reactivity to physical and stress manipulations. However, sympathetic activity at rest has not been well studied in FMS. Sweating is exclusively controlled by sympathetic mechanisms. In this study, skin conductance (SC), as an indirect measure of sweating, was analyzed in 45 women with FMS and 38 healthy women. Tonic SC levels were recorded during a 4-minute rest period, and a breathing maneuver consisting of deep breathing with posterior breath holding was used to evoke SC responses. Associations of tonic SC with state anxiety and body temperature, measured in the hand, were explored to determine sweat functionality. The results showed reduced tonic SC levels, with a less marked decrease in SC during the recording period, and blunted SC reactivity to the breathing manipulation in FMS patients relative to healthy participants. Positive associations of SC with state anxiety and body temperature were observed in healthy participants, but these associations were absent in FMS patients. These results indicate alterations of sweating in FMS, suggesting reduced tonic and reactivity sympathetic influences. Furthermore, the absence of associations between SC levels and state anxiety and body temperature in the patient sample suggested a loss of functionality of the autonomic nervous system in FMS. Diminished autonomic regulation in FMS would reduce the ability to cope with environmental demands, thus favoring increases in stress and pain levels. Finally, the observed reduction in sweating is in accordance with evidence of small nerve fiber neuropathy in FMS.

Sensor Technologies to Manage the Physiological Traits of Chronic Pain: A Review

Non-oncologic chronic pain is a common high-morbidity impairment worldwide and acknowledged as a condition with significant incidence on quality of life. Pain intensity is largely perceived as a subjective experience, what makes challenging its objective measurement. However, the physiological traces of pain make possible its correlation with vital signs, such as heart rate variability, skin conductance, electromyogram, etc., or health performance metrics derived from daily activity monitoring or facial expressions, which can be acquired with diverse sensor technologies and multisensory approaches. As the assessment and management of pain are essential issues for a wide range of clinical disorders and treatments, this paper reviews different sensor-based approaches applied to the objective evaluation of non-oncological chronic pain. The space of available technologies and resources aimed at pain assessment represent a diversified set of alternatives that can be exploited to address the multidimensional nature of pain.

Subgroups in chronic low back pain patients - a step toward cluster-based, tailored treatment in inpatient standard care: On the need for precise targeting of treatment for chronic low back pain

Objective: The purpose of this study was to find applicable clusters for the development of different treatment pathways in an inpatient multimodal pain-therapy setting based on the multifaceted nature of CLBP. Methods: Based on data of questionnaires (Hospital Anxiety and Depression Scale (HADS), Marburg Questionnaire on Habitual Health Findings (MFHW), quality of life assessment using the Short-Form 12 (SF 12)), a retrospective two-step cluster analysis involving a sample of chronic low back pain (CLBP) patients (N=320) was calculated. Subsequently, the clusters were precisely described and compared on the basis of further data collected during the patients' standard care: pain characteristics, socio-demographic data and the general state of health, psychological variables, therapy intensity, and Diagnosis Related Groups (DRG) data. Results: We found a three-cluster solution: little psychological interference but marginal physical and mental quality of life (Cluster 1); poor well-being, low physical quality of life, and marginal mental quality of life (Cluster 2); and heavy mental strain and marginal physical quality of life (Cluster 3). Conclusions: Similar to previous studies, our results suggest that patients suffering from CLBP differ with regard to the magnitude of mental burden and the presence of physical impairment. These differences ascertain the need for precise targeting of treatment for CLBP. Inpatient pain centers therefore should offer different multimodal therapy pathways and integrate a meaningful triage, taking into account the multifaceted nature of CLBP based on sophisticated knowledge about forms, differences, and relationships among the biopsychosocial components of CLBP.

Cardiovascular Responses of Women with Fibromyalgia to a Laboratory Stressor: Does Post-traumatic Stress Disorder Comorbidity Matter?

OBJECTIVES

This study compared cardiovascular responses to a laboratory trauma-unrelated stressor of two groups of women diagnosed with fibromyalgia (FM), one of them with comorbid post-traumatic stress disorder (PTSD), with a group of healthy controls in order to detect the possible existence of differences linked to comorbidity.

DESIGN

Case-controls.

METHODS

Eighteen women diagnosed with FM and comorbid PTSD, 18 women diagnosed with FM and no PTSD, and 38 healthy women were exposed to an arithmetic task with harassment while blood pressure and heart rate were measured during task exposure and recovery.

RESULTS

Although heart rate response evidenced a general blunted reactivity for both groups of FM patients, only those with comorbid PTSD presented lower levels of reactivity in terms of their systolic blood pressure response. In addition, systolic blood pressure response was sensitive to the presence of depression in both groups of FM patients and controls. Finally, although both groups of FM patients showed significantly slower rates of recovery, their final recovery state was not worse after twelve minutes of recording.

CONCLUSIONS

Results of this study point to comorbid PTSD as a significant contributor to the blunted cardiovascular reactivity observed in FM patients, which may be dependent to a great extent on depressive symptomatology. As some degree of cardiovascular response to stress is functional in that it mobilizes energy and triggers the necessary compensatory mechanisms to manage stressors, this study supports the well-recognized clinical strategies of detection and treatment of PTSD and concomitant depression in the management of FM.

Efficacy of Biofeedback in Chronic back Pain: a Meta-Analysis

PURPOSE

The aims of the present analysis were to investigate the short- and long-term efficacy and treatment moderators of biofeedback as a psychological treatment option for chronic back pain.

METHOD

A literature search using PubMed, PsycINFO, and the Cochrane Library identified 21 eligible studies including 23 treatment conditions and 1062 patients.

RESULTS

Meta-analytic integration resulted in a significant small-to-medium effect size for pain intensity reduction (Hedges' g = 0.60; 95 % confidence interval (CI) 0.44, 0.76) that proved to be stable with a significant small-to-large effect size (Hedges' g = 0.62; 95 % CI 0.40, 0.84) over an average follow-up phase of 8 months. Biofeedback also proved to be effective in reducing depression (Hedges' g = 0.40; 95 % CI 0.27, 0.52), disability (Hedges' g = 0.49; 95 % CI 0.34, 0.74), reduction of muscle tension (EMG; Hedges' g = 0.44; 95 % CI 0.22, 0.65), and improving cognitive coping (Hedges' g = 0.41; 95 % CI 0.26, 0.57). These effects remained comparatively stable at follow-up and for controlled studies only. Moderator analyses revealed longer biofeedback treatments to be more effective for reducing disability and a greater proportion of biofeedback in the treatment to be more effective for reducing depression. Publication bias analyses demonstrated the consistency of these effects.

CONCLUSION

It is concluded that biofeedback treatment can lead to improvements on various pain-related outcomes in the short and long terms, both as a standalone and as an adjunctive intervention.

Suicide risk in patients with migraine and comorbid fibromyalgia

OBJECTIVES

To identify the frequency, clinical effects, and suicide risk in comorbid fibromyalgia(FM) among patients with migraine.

METHODS

We surveyed patients with migraine who attended a headache clinic. All patients completed questionnaires containing demographics, headache profiles based on the International Classification of Headache Disorders, 2nd edition, FM questionnaires based on the modified 2010 American College of Rheumatology preliminary diagnostic criteria, Migraine Disability Assessment, Hospital Anxiety and Depression Scale, and Pittsburgh Sleep Quality Index. Suicide risk was evaluated by self-report of lifetime suicidal ideation and attempts.

RESULTS

Of the 1,318 recruited patients with migraine (aged 42.6 ± 12.7 years; female/male = 4.5), 10.1% (aged 44.3 ± 12.6 years; female/male = 7.9) had comorbidity of FM. Patients with migraine and comorbid FM had higher headache frequency and headache-related disability, poor sleep quality, and were more depressed/anxious than those with migraine only (p < 0.001). Suicidal ideation and attempts were reported in 27.3% and 6.9% of patients with migraine, respectively, and were higher in patients with comorbid FM than in those without (ideation: 58.3% vs 24%; attempt: 17.6% vs 5.7%; p < 0.001). In addition, comorbidity of FM was associated with a higher suicide risk in 3 different migraine subgroups, i.e., migraine without aura, migraine with aura, and chronic migraine. After controlling for covariates, comorbidity of FM remained as a predictor of suicidal ideation and attempts (odds ratio 2.61 and 1.99, respectively, p < 0.05)in patients with migraine.

CONCLUSIONS

Comorbidity with FM is associated with a high suicide risk in patients with migraine.

Physiological parameters as a tool in the diagnosis of fibromyalgia syndrome in females: A preliminary study

AIMS

Although fibromyalgia (FM) syndrome is associated with many symptoms, there is as yet no specific finding or laboratory test diagnostic of this syndrome. The physical examination and laboratory tests may be helpful in figuring out this syndrome.

MATERIALS AND METHODS

The heart rate, respiration rate, body temperature (TEMP), height, body weight, hemoglobin level, erythrocyte sedimentation rate, white blood cell count, platelet count (PLT), rheumatoid factor and C-reactive protein levels and electrocardiograms (ECG) of FM patients were compared with those of control individuals. In addition, the predictive value of these tests was evaluated via receiver operating characteristic (ROC) analysis.

KEY FINDINGS

The results showed that the TEMP and the PLT were higher in the FM group compared with the control group. Also, ST heights in ECGs which corresponds to a period of ventricle systolic depolarization, showed evidence of a difference between the FM and the control groups. There was no difference observed in terms of the other parameters. According to the ROC analysis, PLT, TEMP and ST height have predictive capacities in FM.

SIGNIFICANCE

Changes in hormonal factors, peripheral blood circulation, autonomous system activity disorders, inflammatory incidents, etc., may explain the increased TEMP in the FM patients. The high PLT level may signify a thromboproliferation or a possible compensation caused by a PLT functional disorder. ST depression in FM patients may interrelate with coronary pathology. Elucidating the pathophysiology underlying the increases in TEMP and PLT and the decreases in ST height may help to explain the etiology of FM.

Combining voice therapy and physical therapy: A novel approach to treating muscle tension dysphonia

OBJECTIVE

This study investigated the role of a specialized physical therapy program for muscle tension dysphonia patients as an adjunct to standard of care voice therapy.

STUDY DESIGN

Retrospective Cohort Study Methods Adult MTD patients seen between 2007 and 2012 were identified from the clinical database. They were prescribed voice therapy and, if concomitant neck pain, adjunctive physical therapy. In a pragmatic observational cohort design, patients underwent one of four potential treatment approaches: voice therapy alone (VT), voice therapy and physical therapy (VT+PT), physical therapy alone (PT), or incomplete/no treatment. Voice handicap outcomes were compared between treatment approaches.

RESULTS

Of 153 patients meeting criteria (Median age 48 years, 68% female, and 30% had fibromyalgia, chronic pain, chronic fatigue, depression, and/or anxiety), there was a similar distribution of patients with moderate or severe pre-treatment VHI scores across treatment groups (VT 45.5%, VT+PT 43.8%, PT 50%, no treatment 59.1%; p=0.45). Patients treated with VT alone had significantly greater median improvement in VHI than those not treated: 10-point vs. 2-point (p=0.02). Interestingly, median VHI improvement in patients with baseline moderate-severe VHI scores was no different between VT (10), VT+PT (8) and PT alone (10; p=0.99).

CONCLUSIONS

Findings show voice therapy to be an effective approach to treating MTD. Importantly, other treatment modalities incorporating physical therapy had a similar, albeit not significant, improvement in VHI. This preliminary study suggests that physical therapy techniques may have a role in the treatment of a subset of MTD patients. Larger, comparative studies are needed to better characterize the role of physical therapy in this population.

LEARNING OUTCOMES

The reader will describe symptoms associated with muscle tension dysphonia and current treatment. The reader will describe the systematic adjunctive physical therapy approach and understand the rationale to consider incorporation of physical therapy into the current treatment regimen.

The lateral prefrontal cortex mediates the hyperalgesic effects of negative cognitions in chronic pain patients

Although high levels of negative affect and cognitions have been associated with greater pain sensitivity in chronic pain conditions, the neural mechanisms mediating the hyperalgesic effect of psychological factors in patients with pain disorders are largely unknown. In this cross-sectional study, we hypothesized that 1) catastrophizing modulates brain responses to pain anticipation and 2) anticipatory brain activity mediates the hyperalgesic effect of different levels of catastrophizing in fibromyalgia (FM) patients. Using functional magnetic resonance imaging, we scanned the brains of 31 FM patients exposed to visual cues anticipating the onset of moderately intense deep-tissue pain stimuli. Our results indicated the existence of a negative association between catastrophizing and pain-anticipatory brain activity, including in the right lateral prefrontal cortex. A bootstrapped mediation analysis revealed that pain-anticipatory activity in the lateral prefrontal cortex mediates the association between catastrophizing and pain sensitivity. These findings highlight the role of the lateral prefrontal cortex in the pathophysiology of FM-related hyperalgesia and suggest that deficits in the recruitment of pain-inhibitory brain circuitry during pain-anticipatory periods may play an important contributory role in the association between various degrees of widespread hyperalgesia in FM and levels of catastrophizing, a well-validated measure of negative cognitions and psychological distress.

PERSPECTIVE

This article highlights the presence of alterations in pain-anticipatory brain activity in FM. These findings provide the rationale for the development of psychological or neurofeedback-based techniques aimed at modifying patients' negative affect and cognitions toward pain.

Fibromyalgia and its clinical relevance in renal transplant recipients

OBJECTIVE

Recent evidence suggests that fibromyalgia syndrome (FS) is associated with inflammation and endothelial dysfunction. Our aim was to determine the prevalence of FS in renal transplant recipients and to identify possible links between FS and clinical and laboratory parameters.

METHODS

Ninety-nine kidney transplant recipients with normal graft functions (37.15 ± 10.83 years old, 67 male) were enrolled in the study. All subjects completed the Fibromyalgia Impact Questionnaire (FIQ). The biochemical and clinical parameters in the 1st post-transplantation year were retrospectively recorded. Cardiovascular parameters, including body composition analyses (Tanita), ambulatory blood pressure monitoring data, and pulse-wave velocity, were cross-sectionally analyzed.

RESULTS

Mean FIQ score for the whole group was 21.4 ± 14.7. Eight patients had FIQ score >50, and these patients had significantly higher left ventricular mass index than patients with lower FIQ score (P = .048). Patients were divided according to their physical impairment score (PIS): PIS ≥5 (n = 50) and PIS <5 (n = 49). Patients with higher PIS had significantly higher serum creatinine (P = .047) and lower eGFR values (P = .008) than patients with lower PIS. Patients were also evaluated with the use of the stiffness score (SS): patients with (n = 41) and without (n = 58) stiffness. Patients with stiffness had significantly higher office systolic (P = .027) and diastolic (P = .044) blood pressure, body mass index (P = .033), and sagittal abdominal diameter (P = .05) than patients without stiffness. Decline in estimated glomerular filtration rate levels were significantly higher in patients with higher FIQ (7.6% vs 9.4%; P = .0001) than in other patients.

CONCLUSIONS

FS in renal transplant recipients was strongly associated with hypertension, arterial stiffness, obesity, and renal allograft dysfunction.

Reaction time, cerebral blood flow, and heart rate responses in fibromyalgia: Evidence of alterations in attentional control

The study investigated cerebral blood flow (CBF) and heart rate (HR) responses during a cued reaction time (RT) task in patients with fibromyalgia syndrome (FMS). CBF velocities in the middle (MCA) and anterior (ACA) cerebral arteries of both hemispheres were recorded in 46 patients and 32 healthy control participants using functional transcranial Doppler sonography (fTCD). Patients exhibited markedly longer RT than healthy participants. Group differences in CBF responses were mainly observed for both ACAs, with greater right hemispherical increases but lower left hemispherical increases in FMS patients than in healthy participants. HR deceleration around the imperative stimulus was more pronounced in healthy participants. RT was inversely related to increases in CBF in both right arteries and in the left ACA in the FMS group, but was positively associated with CBF responses in all four arteries in healthy participants. The magnitude of task-induced HR deceleration correlated negatively with RT in both groups. Patients' clinical pain severity was positively associated with RT and CBF responses; trait anxiety and insomnia were secondary negative predictors of CBF responses. The study provided evidence of a deficit in the alertness component of attention in FMS at behavioral, CBF, and autonomic levels. These results may be interpreted in terms of the neural efficiency hypothesis of intelligence (i.e., less efficient brain activation during cognition in FMS) and the interfering effect of clinical factors on cognition. Clinical factors such as pain, anxiety, and sleep disturbances can affect cognition in FMS by interfering with CBF adjustment to cognitive demands.

Psychological aspects of chronic musculoskeletal pain

Chronic musculoskeletal pain, by its very nature, is associated with negative emotions and psychological distress. There are individual differences in personality, coping skills, behavioral adaptation, and social support that dramatically alter the psychological outcomes of patients with chronic pain. Patients who have an aspect of central pain amplification associated with mechanical or inflammatory pain and patients with fibromyalgia (FM) are likely to exhibit higher levels of psychological distress and illness behaviors. This manuscript discusses several different constructs for the association between chronic pain, central pain amplification, and psychological distress. The first key question addresses mechanisms shared in common between chronic pain and mood disorders, including the individual factors that influence psychological comorbidity, and the second addresses how pain affects mood and vice versa. Finally, the utility of cognitive behavioral approaches in the management of chronic pain symptoms is discussed.

Disrupted brain circuitry for pain-related reward/punishment in fibromyalgia

OBJECTIVE

While patients with fibromyalgia (FM) are known to exhibit hyperalgesia, the central mechanisms contributing to this altered pain processing are not fully understood. This study was undertaken to investigate potential dysregulation of the neural circuitry underlying cognitive and hedonic aspects of the subjective experience of pain, such as anticipation of pain and anticipation of pain relief.

METHODS

Thirty-one FM patients and 14 controls underwent functional magnetic resonance imaging, while receiving cuff pressure pain stimuli on the leg calibrated to elicit a pain rating of ~50 on a 100-point scale. During the scan, subjects also received visual cues informing them of the impending onset of pain (pain anticipation) and the impending offset of pain (relief anticipation).

RESULTS

Patients exhibited less robust activation during both anticipation of pain and anticipation of relief within regions of the brain commonly thought to be involved in sensory, affective, cognitive, and pain-modulatory processes. In healthy controls, direct searches and region-of-interest analyses of the ventral tegmental area revealed a pattern of activity compatible with the encoding of punishment signals: activation during anticipation of pain and pain stimulation, but deactivation during anticipation of pain relief. In FM patients, however, activity in the ventral tegmental area during periods of pain and periods of anticipation (of both pain and relief) was dramatically reduced or abolished.

CONCLUSION

FM patients exhibit disrupted brain responses to reward/punishment. The ventral tegmental area is a source of reward-linked dopaminergic/γ-aminobutyric acid-releasing (GABAergic) neurotransmission in the brain, and our observations are compatible with reports of altered dopaminergic/GABAergic neurotransmission in FM. Reduced reward/punishment signaling in FM may be related to the augmented central processing of pain and reduced efficacy of opioid treatments in these patients.

Chronic low back pain patient groups in primary care--a cross sectional cluster analysis

Background

Due to the heterogeneous nature of chronic low back pain (CLBP), it is necessary to identify patient groups and evaluate treatments within these groups. We aimed to identify groups of patients with CLBP in the primary care setting.

Methods

We performed a k-means cluster analysis on a large data set (n = 634) of primary care patients with CLBP. Variables of sociodemographic data, pain characteristics, psychological status (i.e., depression, anxiety, somatization), and the patient resources of resilience and coping strategies were included.

Results

We found three clusters that can be characterized as “pensioners with age-associated pain caused by degenerative diseases”, “middle-aged patients with high mental distress and poor coping resources”, and “middle-aged patients who are less pain-affected and better positioned with regard to their mental health”.

Conclusions

Our results supported current knowledge concerning groups of CLBP patients in primary care. In particular, we identified a group that was most disabled and distressed, and which was mainly characterized by psychological variables. As shown in our study, pain-related coping strategies and resilience were low in these patients and might be addressed in differentiating treatment strategies. Future studies should focus on the identification of this group in order to achieve effective treatment allocation.

Trial registration

German Clinical Trial Register DRKS00003123

The impact of emotion-related autonomic nervous system responsiveness on pain sensitivity in female patients with fibromyalgia

OBJECTIVE

Patients with fibromyalgia have shown hyporeactive autonomic nervous system (ANS) responses to physical stressors, augmented pain to ANS changes, and heightened negative emotions, which can increase pain. This study examined ANS reactivity to negative emotions and its association with pain in fibromyalgia and control participants.

METHODS

Sixty-two women with fibromyalgia and 59 women in a control group recalled neutral, and anger- and sadness-eliciting experiences while ANS activity was monitored. Clinical and experimental pain were assessed in response to each emotion.

RESULTS

Compared with neutral recall, heart rate (p = .050), mean arterial pressure (p < .001), and high-frequency heart rate variability (p = .012) increased in response to sadness, whereas heart rate decreased (p = .002) and mean arterial pressure increased (p < .001) in response to anger; however, ANS responses did not differ between patients and control participants (all p > .29). Among patients only, decreased preejection period (anger-pain threshold: r = 0.31, p = .018) and total peripheral resistance in response to negative emotions (anger-pain tolerance: r = 0.35, p = .025; sadness-pain threshold: r = 0.51, p < .001; sadness-pain tolerance: r = 0.61, p < .001) correlated with more pain.

CONCLUSIONS

These data suggest that the ANS is not hyporesponsive to elicited emotions in fibromyalgia; however, patients with a larger pain response showed an ANS response pattern reflecting heightened β-adrenergic and reduced α-adrenergic reactivity. Future research should test whether a specific ANS response pattern to emotions is a consequence of increased pain or whether it amplifies pain.

Efficacy of EMG- and EEG-Biofeedback in Fibromyalgia Syndrome: A Meta-Analysis and a Systematic Review of Randomized Controlled Trials

Objectives. Biofeedback (BFB) is an established intervention in the rehabilitation of headache and other pain disorders. Little is known about this treatment option for fibromyalgia syndrome (FMS). The aim of the present review is to integrate and critically evaluate the evidence regarding the efficacy of biofeedback for FMS. Methods. We conducted a literature search using Pubmed, clinicaltrials.gov (National Institute of Health), Cochrane Central Register of Controlled Trials, PsycINFO, SCOPUS, and manual searches. The effect size estimates were calculated using a random-effects model. Results. The literature search produced 123 unique citations. One hundred sixteen records were excluded. The meta-analysis included seven studies (321 patients) on EEG-Biofeedback and EMG-Biofeedback. In comparison to control groups, biofeedback (BFB) significantly reduced pain intensity with a large effect size (g = 0.79; 95% CI: 0.22–1.36). Subgroup analyses revealed that only EMG-BFB and not EEG-BFB significantly reduced pain intensity in comparison to control groups (g = 0.86; 95% CI: 0.11–1.62). BFB did not reduce sleep problems, depression, fatigue, or health-related quality of life in comparison to a control group. Discussion. The interpretation of the results is limited because of a lack of studies on the long-term effects of EMG-BFB in FMS. Further research should focus on the long-term efficacy of BFB in fibromyalgia and on the identification of predictors of treatment response.

The behavioral impact of baroreflex function: a review

The baroreflex consists of a negative feedback loop adjusting heart activity to blood pressure fluctuations. This review is concerned with interactions between baroreflex function and behavior. In addition to changes in baroreflex cardiac control subject to behavioral manipulations, interindividual differences in reflex function predicted psychological and central nervous features. The sensitivity of the reflex was inversely related to cognitive performance, evoked potential amplitudes, experimental pain sensitivity, and the severity of clinical pain. Possible variables moderating the strength of the associations are tonic blood pressure, gender, and psychiatric disease. It is suggested that these observations reflect inhibition of higher brain function by baroreceptor afferents. While in many cases increased baroreflex function implies stronger inhibition, individual and situational factors modulate the behavioral impact of cardiac regulation.

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.

Frequency shifts in the anterior default mode network and the salience network in chronic pain disorder

BACKGROUND

Recent functional imaging studies on chronic pain of various organic etiologies have shown significant alterations in both the spatial and the temporal dimensions of the functional connectivity of the human brain in its resting state. However, it remains unclear whether similar changes in intrinsic connectivity networks (ICNs) also occur in patients with chronic pain disorder, defined as persistent, medically unexplained pain.

METHODS

We compared 21 patients who suffered from chronic pain disorder with 19 age- and gender-matched controls using 3T-fMRI. All neuroimaging data were analyzed using both independent component analysis (ICA) and power spectra analysis.

RESULTS

In patients suffering from chronic pain disorder, the fronto-insular 'salience' network (FIN) and the anterior default mode network (aDMN) predominantly oscillated at higher frequencies (0.20 - 0.24 Hz), whereas no significant differences were observed in the posterior DMN (pDMN) and the sensorimotor network (SMN).

CONCLUSIONS

Our results indicate that chronic pain disorder may be a self-sustaining and endogenous mental process that affects temporal organization in terms of a frequency shift in the rhythmical dynamics of cortical networks associated with emotional homeostasis and introspection.

Stress and resilience in rheumatic diseases: a review and glimpse into the future

Stress resilience factors, and interventions to ease stress and enhance resilience, are gaining increasing attention for the treatment of rheumatic conditions. This Review presents a digest of empirical work on the factors that determine the risk of adapting poorly to a rheumatic condition, and on the resilience factors that counteract such risks. We consider the types of stress-management and resilience treatments that are most effective in promoting the physical and psychological functioning of patients at risk of long-term adjustment problems. Prospective research shows that cognitive-behavioral and social risk and resilience factors predict the long-term physical and psychological functioning of patients with rheumatic conditions. Furthermore, validated screening instruments are becoming increasingly useful in clinical practice to identify and select patients at risk. Stress-management and resilience interventions offer promising ways to improve the long-term functioning of patients. These treatment methods might be especially useful when they are tailored to the specific risk and resilience factors of patients, and when they incorporate innovative approaches to the delivery of services, including internet applications such as eHealth, to increase efficiency and availability of treatments, and to optimize patient empowerment in rheumatic conditions.

Electrodermal activity in response to empathic statements in clinical interviews with fibromyalgia patients

OBJECTIVE

To study patients' electrodermal response (1) to an interviewer's empathic statements vs. inattention to emotional concerns and (2) to the emotional content in clinical interviews.

METHODS

Patients with fibromyalgia (n=48) were given a clinical interview in a randomized 2×2 design, in which interviewer empathic or inattentive behavior (scenario A) and the emotional or neutral content of the interview (scenario B) were manipulated. Electrodermal activity (EDA) was measured during the interview. The patients' affective state (PANAS) and patient satisfaction were also assessed.

RESULTS

In scenario A a significant main effect of empathy was found, indicating an increased tonic EDA (skin conduction level, SCL) during the empathy condition (p<.05). In scenario B there was a main effect of empathy (p<.01) and a significant empathy×content interaction effect (p<.01). There was a strong positive association between empathy and patient satisfaction (p<.0001).

CONCLUSIONS

Empathic statements by the interviewer were associated with increased SCL in patients, most so in interviews with emotional content.

PRACTICE IMPLICATIONS

Psychophysiological variables such as EDA may be applied in clinical communication research on emotional communication, but the limitations of such measures should also be recognized.

Autonomic cardiovascular control and responses to experimental pain stimulation in fibromyalgia syndrome

OBJECTIVE

This study involves a comprehensive investigation of autonomic cardiovascular regulation in fibromyalgia syndrome (FMS) at rest and during painful stimulation and its association with pain indices.

METHODS

In 35 patients and 29 healthy controls, electrocardiography, impedance cardiography, and finger continuous blood pressure measurements were conducted. For the purpose of experimental pain induction, a cold pressor test was applied.

RESULTS

FMS patients showed lower pain threshold and tolerance, as well as higher ratings of pain intensity and unpleasantness on visual analogue scales. Resting stroke volume, myocardial contractility, R-R interval, heart rate variability, and sensitivity of the cardiac baroreflex were reduced in the patients, and increases in stroke volume and myocardial contractility during cold pressor stimulation were less pronounced. In the whole sample as well as in the FMS group, baroreflex sensitivity was inversely associated with subjective pain intensity, and a higher number of baroreflex operations per unit of time predicted higher pain tolerance.

CONCLUSIONS

The data suggest impaired autonomic cardiovascular regulation in FMS in terms of reduced sympathetic and parasympathetic influences, as well as blunted sympathetic reactivity to acute stress. The association between baroreflex function and pain experience reflects the pain inhibition mediated by the baroreceptor system. Given the reduced baroreflex sensitivity in FMS, one may assume deficient ascending pain inhibition arising from the cardiovascular system, which may contribute to the exaggerated pain sensitivity of FMS.