Perception of noxious and innocuous heat stimulation among healthy women and women with fibromyalgia: association with mood, somatic focus, and catastrophizing

The role of quantitative sensory testing in the evaluation of musculoskeletal pain conditions

Quantitative sensory testing (QST) is a noninvasive method of assessing sensory and pain perception that has been used in the past 30 years primarily for analysis of cutaneous and mucosal perception. In recent years, several published studies have demonstrated that QST may be useful in the analysis of painful musculoskeletal disorders as well. Based on the results of these studies, it can be postulated that QST may be useful in the analysis of the pathogenesis, classification, and differential diagnosis of musculoskeletal disorders. However, due to the diverse ethiopathogenetic basis of these disorders, a broad range of QST test batteries may be necessary to analyze the various musculoskeletal disease entities. This review analyzes published studies on this subject and summarizes current information on altered sensory and pain perception available for some of the most common musculoskeletal disorders. At present, QST remains primarily a research tool but may be useful in differential diagnosis in indicating the presence of central sensitization and for clinical monitoring of disease progression or treatment response.

[CNS processing of pain in functional somatic syndromes]

Functional pain syndromes usually are characterized by a local or generalized increase in pain sensitivity, spontaneous ongoing pain, and a variety of other common symptoms. Classification or definition of a syndrome is usually somewhat arbitrarily based on the predominantly affected body region or a main symptom, resulting in significant overlap between conditions. Support for the involvement of the central nervous system (CNS) comes from the frequent comorbidity of affective disorders and symptomatology, disturbances in cognitive function, changes in neuroendocrine function, and dysregulation of the autonomic nervous system, although only subgroups of patients are affected. Findings of neuroimaging studies in functional pain syndromes typically reveal plausible correlates for the patients' subjective complaints and indicate a central augmentation in pain processing but also in other sensory systems including a postulated interoceptive system. The pathophysiology of this augmentation is not clear, and the importance of peripheral input remains unresolved, as well as the contribution of spinal and supraspinal mechanisms. Affective and cognitive factors clearly influence pain processing in these syndromes, but do not fully explain the observed augmentation. For FMS, chronic low back pain, and irritable bowel syndrome a dysfunction of the descending inhibitory systems is supported by these findings. However, longitudinal studies are needed to confirm the causality of the reported associations and to establish a primary role of the CNS in these syndromes. Current techniques like VBM and H-MRS have revealed potential yet highly variable structural abnormalities of the CNS in several of the syndromes, but clinical relevance and conclusions from these studies remain far from clear. New theoretical concepts should drive prospective and interdisciplinary research based on well-defined hypotheses to use the full potential of the current neuroimaging techniques.

Sequential analyses of daily symptoms in women with fibromyalgia syndrome

Fibromyalgia syndrome (FMS) is a chronic musculoskeletal pain disorder characterized by generalized pain, chronic fatigue, sleep disturbance, and a range of other symptoms having no definitive pathology. Consequently, patient evaluations rely on self-report. Ecological Momentary Assessment (EMA) allows frequent real-time collection of self-report measures, removing recall bias and increasing external validity. We studied 81 females with FMS aged 18 to 42 years. Participants carried EMA devices (Palm Pilot M100) programmed to request ratings to 8 FMS symptoms/conditions 3 times daily for 30 days. Completeness of response rates varied across participants and over time. Controlling for immediately previous fatigue (ie, fatigue rating from the immediately preceding rating), unit increases in immediately previous pain and immediately previous emotional distress predicted 9 and 7% increases, respectively, in current fatigue. Controlling for immediately previous emotional distress, a unit increase in immediately previous pain predicted 7% increase in current emotional distress. Controlled for immediately previous pain, a unit increase in immediately previous fatigue predicted a 7% increase in current pain, enhanced by prior diurnal effects; immediately previous emotional distress was not significant. Collectively these results suggest an asymmetry in which emotional stress and pain may increase fatigue, fatigue but not emotional distress may increase pain, and pain but not fatigue may increase emotional distress. Despite small effects and person-to-person variability, these findings suggest that longitudinal data collection by EMA may reveal sequential or causal explanatory patterns with important clinical implications.

PERSPECTIVE

Understanding how multiple symptoms covary in FMS is essential for optimal treatment planning. Our results show small but significant temporal relations among pain, fatigue, and emotional distress. Our results also provide support for the use of EMA as a viable data collection method that allows longitudinal, real-time assessment of multiple FMS symptoms.

Perspectives on fatigue from the study of chronic fatigue syndrome and related conditions

Fatigue is a symptom whose causes are protean and whose phenotype includes physical, mood, and behavioral components. Chronic fatigue syndrome (CFS) is an illness that has strong biological underpinnings and no definite etiology. Diagnostic criteria established by the Centers for Disease Control and Prevention have helped classify CFS as an overlap of mood, behavioral, and biological components. These include the presence of fatigue for more than 6 months associated with a diminution of functional activity and somatic symptoms, and pain not attributable to a specific diagnosis or disease. Four of the following criteria need to be present: sore throat, impaired memory or cognition, unrefreshing sleep, postexertional fatigue, tender glands, aching stiff muscles, joint pain, and headaches. Many researchers have observed that CFS shares features in common with other somatic syndromes, including irritable bowel syndrome, fibromyalgia, and temporomandibular joint dysfunction. Correlations between inflammation and infection, augmented sensory processing, abnormalities of neurotransmitters, nerve growth factors, low levels of serotonin and norepinephrine, abnormalities of homeostasis of the stress system, and autonomic dysfunction may be hallmarks of CFS. The relative contributions of each of these abnormalities to the profound fatigue associated with CFS need to be explored further to better evaluate and treat the syndrome.

Alteration of cortical excitability in patients with fibromyalgia

We assessed cortical excitability and intracortical modulation systematically, by transcranial magnetic stimulation (TMS) of the motor cortex, in patients with fibromyalgia. In total 46 female patients with fibromyalgia and 21 normal female subjects, matched for age, were included in this study. TMS was applied to the hand motor area of both hemispheres and motor evoked potentials (MEPs) were recorded for the first interosseous muscle of the contralateral hand. Single-pulse stimulation was used for measurements of the rest motor threshold (RMT) and suprathreshold MEP. Paired-pulse stimulation was used to assess short intracortical inhibition (SICI) and intracortical facilitation (ICF). Putative correlations were sought between changes in electrophysiological parameters and major clinical features of fibromyalgia, such as pain, fatigue, anxiety, depression and catastrophizing. The RMT on both sides was significantly increased in patients with fibromyalgia and suprathreshold MEP was significantly decreased bilaterally. However, these alterations, suggesting a global decrease in corticospinal excitability, were not correlated with clinical features. Patients with fibromyalgia also had lower ICF and SICI on both sides, than controls, these lower values being correlated with fatigue, catastrophizing and depression. These neurophysiological alterations were not linked to medication, as similar changes were observed in patients with or without psychotropic treatment. In conclusion, fibromyalgia is associated with deficits in intracortical modulation involving both GABAergic and glutamatergic mechanisms, possibly related to certain aspects of the pathophysiology of this chronic pain syndrome. Our data add to the growing body of evidence for objective and quantifiable changes in brain function in fibromyalgia.

A cross-sectional survey of 3035 patients with fibromyalgia: subgroups of patients with typical comorbidities and sensory symptom profiles

OBJECTIVES

Patients with FM are heterogeneous. They present with a variety of pain qualities, sensory abnormalities and additional comorbidities. The aim was to identify clinically distinguishable subgroups of patients.

METHODS

This investigation uses epidemiological and clinical data of 3035 FM patients from a cross-sectional survey (painDETECT) to (i) describe characteristic epidemiological data and comorbidities and (ii) detect subgroups of patients with typical patterns of sensory symptoms and comorbidities.

RESULTS

Clinically relevant sensory abnormalities (strongly, very strongly present) included pressure pain (58%), prickling (33%), burning (30%) and thermal hypersensitivity (24%). Pain attacks were complained by 40% of patients. Moderate to severe comorbid depression occurred in 66% of patients. Only approximately 30% of the patients had optimal sleep. A hierarchical cluster analysis using descriptors of sensory abnormalities as well as the extent of comorbidities revealed five distinct subgroups of patients showing a characteristic clinical profile. Four subgroups of patients suffer from severe sensory disturbances in various combinations but lack pronounced comorbidities. In one subgroup, however, severe comorbidities dominate the clinical picture. Differences in pathophysiological mechanisms of pain generation can be attributed to each subgroup.

CONCLUSIONS

The results of this study indicate that FM patients can be classified on the basis of their sensory symptoms and comorbidities by the use of a patient-reported questionnaire. Subgrouping of patients with FM may be used for future research and to tailor optimal treatment strategies for the appropriate patient.

Somatosensory conflicts in complex regional pain syndrome type 1 and fibromyalgia syndrome

The somatosensory system is an integral component of the motor control system that facilitates the recognition of location and experience of peripheral stimuli, as well as body part position and differentiation. In chronic pain, this system may be disrupted by alterations in peripheral and cortical processing. Clinical symptoms that accompany such changes can be difficult for patients to describe and health care practitioners to comprehend. Patients with chronic pain conditions such as complex regional pain syndrome or fibromyalgia typically describe a diverse range of somatosensory changes. This article describes how sensory information processing can become disturbed in fibromyalgia syndrome and complex regional pain syndrome and how symptoms can potentially be explained by the mechanisms that generate them.

Fibromyalgia: an overview

Fibromyalgia is the diagnosis given to individuals with chronic widespread musculoskeletal pain for which no alternative cause, such as tissue inflammation or damage, can be identified. Fibromyalgia is now believed to be, at least in part, a disorder of central pain processing that produces heightened responses to painful stimuli (hyperalgesia) and painful responses to nonpainful stimuli (allodynia). Aberrations in central pain processing may also be partly responsible for symptoms experienced in several chronic pain disorders that coaggregate with fibromyalgia, which is itself a product of genetic and environmental factors. Thus, aberrational central pain processing is implicated in irritable bowel syndrome, temporomandibular disorder, chronic low back pain, and certain other chronic pain disorders. Fibromyalgia and related disorders appear to reflect deficiencies in serotonergic and noradrenergic, but not opioidergic, transmission in the central nervous system. The heightened state of pain transmission may also be owing to increases in pronociceptive neurotransmitters such as glutamate and substance P. In some cases, psychological and behavioral factors are also in play. Although the overlapping symptomatology between fibromyalgia and related disorders may present diagnostic challenges, proper examination and observation can help clinicians make an accurate diagnosis. In recent years, the vastly improved understanding of the mechanism underlying fibromyalgia and the related spectrum of diseases has fostered rapid advances in the therapy of these chronic pain disorders by both pharmacologic and nonpharmacologic interventions.

Relationships between pain thresholds, catastrophizing and gender in acute whiplash injury

The mechanisms underlying sensory hypersensitivity (SH) in acute whiplash associated disorders (WAD) are not well understood. We examined the extent of the relationships between the sensory measures of pressure pain threshold (PPT) and cold pain threshold (CPT), catastrophizing, pain and disability levels and gender in acute WAD. Thirty-seven subjects reporting neck pain following a motor vehicle accident were examined within five weeks post-injury. Measures of neck pain and disability (Neck Disability Index, NDI) and catastrophizing (Pain Catastrophizing Scale, PCS) were taken. CPT was assessed in the cervical spine and PPTs were assessed in the cervical spine (PPTcx) and at a remote site (PPTdistal). CPT and PCS were moderately correlated (r=0.46; p < 0.01); however there were no significant relationships between PPT (cervical and distal) and PCS. Both CPT (r=0.55, p < 0.01) and PPTcx (r=-0.42, p < 0.01) were significantly correlated with NDI but PPTdistal was not (r=-0.08, p=0.65). Finally, gender modulated the relationships between sensory measures, catastrophizing, and pain and disability levels. In conclusion, subjects with higher levels of catastrophizing presented with sensory hypersensitivity to cold stimuli in the acute phase of whiplash. Differences between genders are in accordance with the growing body of evidence suggesting that the relationships between some psychological factors and injury-related symptoms are modulated by gender.

Fixed belief in cognitive dysfunction despite normal neuropsychological scores: neurocognitive hypochondriasis?

A subset of patients who present for neuropsychological testing report dysfunction in daily life activities secondary to cognitive deficits, but are found on formal testing to have no objective abnormalities, raising the possibility of "neurocognitive hypochondriasis." Such a case is presented, and the factors that appear to give rise to this presentation are explored. Cases of hypochondriacal overconcern regarding cognitive function are likely not rare, particularly given research showing there is little correlation between objective report of cognitive dysfunction and actual test scores in such conditions as mild traumatic brain injury, chronic fatigue syndrome, fibromyalgia, toxic mold exposure, and post-polio syndrome.

Understanding fibromyalgia: lessons from the broader pain research community

Fibromyalgia (FM) is a chronic pain condition marked by centrally mediated augmentation of pain and sensory processes. Skepticism has marked the history of this condition, but more recent study has identified neurobiological underpinnings supporting many of the symptoms associated with this condition. Early research in FM had unprecedented latitude within the rheumatology community to borrow heavily from theory and methods being applied in chronic pain research more generally. These insights facilitated rapid advances in FM research, not the least of which was the abandonment of a peripheral focus in favor of studying central mechanisms associated with central augmentation. Currently, rapid-paced discovery is taking place in FM genetics, patient assessment, new therapeutic targets, and novel methods of treatment delivery. Such insights are not likely to be limited in application just to FM and could have relevance to the broader field of pain research as well.

PERSPECTIVE

This manuscript reviews the history of FM and its diagnosis, evidence supporting central augmentation of pain in FM, potential mechanisms of central augmentation, current approaches to integrated care of FM, and areas of active collaboration between FM research and other chronic pain conditions.

Clinical expression profiles of complex regional pain syndrome, fibromyalgia and a-specific repetitive strain injury: More common denominators than pain?

PURPOSE

To systematically evaluate and compare the clinical manifestations, disease course, risk factors and demographic characteristics of Complex Regional Pain Syndrome type 1 (CRPS), fibromyalgia (FM) and a-specific Repetitive Strain Injury (RSI).

METHOD

A literature search was performed using terms related to the aforementioned topics and diseases. Only original clinical studies that included at least 20 subjects were eligible.

RESULTS

Fifty-nine studies on CRPS, 73 on FM and 7 on a-specific RSI were identified. The diseases show similarities in age distribution, male-female ratio, pain characteristics and sensory signs and symptoms. Motor, autonomic and trophic changes are frequently reported in CRPS, but only occasionally in FM and RSI. Systemic symptoms are found in patients with CRPS and FM, and in a subgroup of patients with RSI. In all three disorders, symptoms usually start locally, but may spread to other body regions later, which, in the case of FM, is a prerequisite for diagnosis. Disease onset is always, usually, or occasionally of traumatic origin in RSI, CRPS and FM, respectively. Anxiety and depression are more frequent in patients compared to controls, but probably not very different from patients with other pain conditions or chronic diseases.

CONCLUSIONS

Apart from some obvious differences between CRPS, FM and RSI, the similarities are conspicuous. The common features of CRPS, FM and a-specific RSI may suggest that a common pathway is involved, but until patients with these type of symptoms are assessed with a uniform assessment procedure, a thorough comparison cannot be made. A systematic evaluation of patients with a suspected diagnosis of CRPS, FM or RSI, may lead to a better appreciation of the differences and similarities in these diseases and help to unravel the underlying mechanisms.

Sleep disorders and their association with laboratory pain sensitivity in temporomandibular joint disorder

STUDY OBJECTIVES

We characterized sleep disorder rates in temporomandibular joint disorder (TMD) and evaluated possible associations between sleep disorders and laboratory measures of pain sensitivity.

DESIGN

Research diagnostic examinations were conducted, followed by two consecutive overnight polysomnographic studies with morning and evening assessments of pain threshold.

SETTING

Orofacial pain clinic and inpatient sleep research facility.

PARTICIPANTS

Fifty-three patients meeting research diagnostic criteria for myofascial TMD.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

We determined sleep disorder diagnostic rates and conducted algometric measures of pressure pain threshold on the masseter and forearm. Heat pain threshold was measured on the forearm; 75% met self-report criteria for sleep bruxism, but only 17% met PSG criteria for active sleep bruxism. Two or more sleep disorders were diagnosed in 43% of patients. Insomnia disorder (36%) and sleep apnea (28.4%) demonstrated the highest frequencies. Primary insomnia (PI) (26%) comprised the largest subcategory of insomnia. Even after controlling for multiple potential confounds, PI was associated with reduced mechanical and thermal pain thresholds at all sites (P < 0.05). Conversely, the respiratory disturbance index was associated with increased mechanical pain thresholds on the forearm (P < 0.05).

CONCLUSIONS

High rates of PI and sleep apnea highlight the need to refer TMD patients complaining of sleep disturbance for polysomnographic evaluation. The association of PI and hyperalgesia at a nonorofacial site suggests that PI may be linked with central sensitivity and could play an etiologic role in idiopathic pain disorders. The association between sleep disordered breathing and hypoalgesia requires further study and may provide novel insight into the complex interactions between sleep and pain-regulatory processes.

[Validation of the Spanish version of the Pain Catastrophizing Scale in fibromyalgia]

BACKGROUND AND OBJECTIVE

Pain catastrophization is considered an important risk factor for pain in general and, specifically, for fibromyalgia. There are no validated Spanish versions of any of the questionnaires developed to assess pain catastrophization. The aim of this study was to validate the Spanish version of the Pain Catastrophization Scale (PCS), one of the most used questionnaires to assess pain catastrophization.

PATIENTS AND METHOD

A prospective, observational and multicentre study was carried out in clinically stable and unstable patients with fibromyalgia. Factorial structure, convergent validity, reliability (internal consistency and test-retest) and sensitivity to change were assessed.

RESULTS

Two hundred and thirty patients from 12 primary care health centres were included. The Spanish version of the PCS showed the same 3-factor structure (rumination, magnification and helplessness) described in the original study. It also showed appropriate internal consistency (Cronbach alpha=0.79), test-retest reliability (intraclass correlation coefficient=0.84) and sensitivity to change (effect size<or=2).

CONCLUSIONS

The Spanish version of the PCS shows appropriate psychometric properties, similar to the English original scale. Therefore, PCS could be useful for clinical practice and research in Spanish patients with fibromyalgia.

Treatment options and patient perspectives in the management of fibromyalgia: future trends

Fibromyalgia (FM) is a common, complex, and difficult to treat chronic widespread pain disorder, which usually requires a multidisciplinary approach using both pharmacological and non-pharmacological (education and exercise) interventions. It is a condition of heightened generalized sensitization to sensory input presenting as a complex of symptoms including pain, sleep dysfunction, and fatigue, where the pathophysiology could include dysfunction of the central nervous system pain modulatory systems, dysfunction of the neuroendocrine system, and dysautonomia. A cyclic model of the pathophysiological processes is compatible with the interrelationship of primary symptoms and the array of postulated triggers associated with FM. Many of the molecular targets of current and emerging drugs used to treat FM have been focused to the management of discrete symptoms rather than the condition. Recently, drugs (eg, pregabalin, duloxetine, milnacipran, sodium oxybate) have been identified that demonstrate a multidimensional efficacy in this condition. Although the complexity of FM suggests that monotherapy, non-pharmacological or pharmacological, will not adequately address the condition, the outcomes from recent clinical trials are providing important clues for treatment guidelines, improved diagnosis, and condition-focused therapies.

Habituation and sensitization to heat and cold pain in women with fibromyalgia and healthy controls

The purpose of this study was to examine differences in habituation to heat and cold pain in women with fibromyalgia (FM; n=33) and in women who were healthy controls (HC; n=44). Quantitative sensory testing (QST) was used to assess pain thresholds during five consecutive trials of ascending heat and descending cold stimulation. Anxiety, depression, fatigue, and pain during the previous week were assessed using self-report measures. The overall hypotheses were that there would be differences between groups in pain thresholds and in the rate of habituation to heat and cold pain stimuli. Multilevel modeling was used to test the hypotheses. There were large overall differences in pain thresholds, with the FM group showing greater sensitivity to heat and cold pain stimuli compared with the HC group. While habituation occurred in both of the groups for heat pain, the HC group had stronger habituation across trials than the FM group. Conversely, while the HC group habituated to cold pain stimuli, the FM group showed sensitization and had decreased cold pain thresholds across trials (they felt cold pain at higher temperatures). In addition, anxiety, depression, fatigue, and pain were related to decreased heat and cold pain thresholds in the overall sample. However, when group was controlled, none of these variables were related to thresholds or rates of habituation or sensitization. The differences between women with FM and healthy women in habituation and sensitization may have important implications for the etiology, diagnosis, and treatment of FM and other chronic pain conditions.

Association of catastrophizing with interleukin-6 responses to acute pain

Catastrophizing exerts its deleterious effects on pain via multiple pathways, and some researchers have reported that high levels of catastrophizing are associated with enhanced physiological reactivity to painful stimulation. In this project, 42 generally healthy adults underwent a series of psychophysical pain testing procedures assessing responses to noxious mechanical, heat, and cold stimuli. Pain catastrophizing cognitions were assessed prior to and then immediately after the various pain induction procedures. Blood samples were taken at baseline and then at several time points from the end of the procedures to 1h post-testing. Samples were assayed for serum levels of cortisol and interleukin-6 (IL-6). Both cortisol and IL-6 increased from baseline during the post-testing period (p's<.05), with cortisol returning to baseline by 1h post-testing and IL-6 remaining elevated. Pain catastrophizing, measured immediately after the pain procedures, was unrelated to cortisol reactivity, but was strongly related to IL-6 reactivity (p<.01), with higher levels of catastrophizing predicting greater IL-6 reactivity. In multivariate analyses, the relationship between catastrophizing and IL-6 reactivity was independent of pain ratings. Collectively, these findings suggest that cognitive and emotional responses during the experience of pain can shape pro-inflammatory immune system responses to noxious stimulation. This pathway may represent one important mechanism by which catastrophizing and other psychosocial factors shape the experience of both acute and chronic pain in a variety of settings.

Biology and therapy of fibromyalgia. Evidence-based biomarkers for fibromyalgia syndrome

Researchers studying fibromyalgia strive to identify objective, measurable biomarkers that may identify susceptible individuals, may facilitate diagnosis, or that parallel activity of the disease. Candidate objective measures range from sophisticated functional neuroimaging to office-ready measures of the pressure pain threshold. A systematic literature review was completed to assess highly investigated, objective measures used in fibromyalgia studies. To date, only experimental pain testing has been shown to coincide with improvements in clinical status in a longitudinal study. Concerted efforts to systematically evaluate additional objective measures in research trials will be vital for ongoing progress in outcome research and translation into clinical practice.

Increased bias to report heat or pain following emotional priming of pain-related fear

Emotional and attentional factors have been identified to play a significant role in modulating pain perception with negative emotions increasing pain sensitivity. Recent studies suggest that fearful images may activate the attentional components of fear driven behaviours and facilitate an attentional bias or sensitivity toward noxious stimuli. The current investigation examines whether priming of pain-related fear will affect performance by increasing sensitivity to punctuate heat stimuli. A modified version of the visual dot probe task was employed to provide priming of pain-related fear and a heat detection task was used to measure the effects of priming on sensitivity. The results indicated a significant facilitation of heat and pain perception at varying temperatures following emotional priming. In particular, there was an increase in the bias toward reporting a heat stimulus following emotional priming. The findings emphasise the efficacy of the visual dot probe task as a method of priming and provide a possible method for probing hypervigilance in chronic pain patients.

A psychophysical study of auditory and pressure sensitivity in patients with fibromyalgia and healthy controls

Fibromyalgia (FM) is characterized by widespread tenderness. Studies have also reported that persons with FM are sensitive to other stimuli, such as auditory tones. We hypothesized that subjects with FM would display greater sensitivity to both pressure and auditory tones and report greater sensitivity to sounds encountered in daily activities. FM subjects (n = 30) and healthy control subjects (n = 28) were administered auditory tones and pressure using the same psychophysical methods to deliver the stimuli and a common way of scaling responses. Subjects were also administered a self-report questionnaire regarding sensitivity to everyday sounds. Participants with FM displayed significantly greater sensitivity to all levels of auditory stimulation (Ps < .05). The magnitude of difference between FM patients' lowered auditory sensitivity (relative to control subjects) was similar to that seen with pressure, and pressure and auditory ratings were significantly correlated in both control subjects and subjects with FM. FM patients also were more sensitive to everyday sounds (t = 8.65, P < .001). These findings support that FM is associated with a global central nervous system augmentation in sensory processing. Further research is needed to examine the neural substrates associated with this abnormality and its role in the etiology and maintenance of FM.

PERSPECTIVE

Muscle tenderness is the hallmark of FM, but the findings of this study and others suggest that persons with FM display sensitivity to a number of sensory stimuli. These findings suggest that FM is associated with a global central nervous system augmentation of sensory information. These findings may also help to explain why persons with FM display a number of comorbid physical symptoms other than pain.

Predictors of wrist function and health status after operative treatment of fractures of the distal radius

PURPOSE

To identify the most important determinants of physician-based and patient-based scoring systems for the wrist and upper extremity after operative treatment of a fracture of the distal radius, with the hypothesis that pain is the strongest determinant of both types of scores.

METHODS

Eighty-four patients were evaluated a minimum of 6 months after operative fixation of an unstable distal radius fracture using 2 physician-based evaluation instruments (the Mayo Wrist Score and the Gartland and Werley Score) and an upper extremity-specific health status questionnaire (Disabilities of the Arm, Shoulder, and Hand; DASH). Multivariate analysis of variance and multiple linear regression modeling were used to identify the degree to which various factors affect variability in the scores derived with these measures.

RESULTS

The physician-based scoring systems showed moderate correlation with each other and with DASH scores. The results of multiple linear regression modeling were as follows (percent variability accounted for by the best fit model/model with top factor alone): Mayo: 54% grip and flexion arc/47% grip alone; Gartland and Werley: 70% pain, flexion arc, radiocarpal arthritis, and duration of follow-up/53% pain alone; DASH: 71% pain, forearm arc, and type of fracture/65% pain alone.

CONCLUSIONS

At early follow-up, pain dominates the patient's perception of function after recovery from an operatively treated distal radius fracture as measured by the DASH score and the physician-based rating according to the system of Gartland and Werley. The Mayo Wrist Score is determined primarily by grip strength rather than pain. Because perception of pain and strength of grip have been shown to be influenced by psychosocial factors in some individuals, both patient-based and physician-based measures of wrist function may be vulnerable to illness behavior.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic III.

Changes in cognitive-behavioral factors and muscle activation patterns after interventions for work-related neck-shoulder complaints: relations with discomfort and disability

OBJECTIVES

Knowledge regarding the working mechanism of an intervention is essential for obtaining a better understanding of the intervention and contributes to optimize its outcome. This study aimed at investigating whether changes in cognitive-behavioral factors and muscle activation patterns after myofeedback training and ergonomic counseling were associated with outcome, in subjects with work-related musculoskeletal neck-shoulder complaints.

METHODS

Seventy-nine symptomatic subjects received either myofeedback with ergonomic counseling (Mfb/EC) or ergonomic counseling alone (EC). Outcome measures discomfort and disability, and process factors catastrophizing, pain control, fear-avoidance beliefs, and muscle activation patterns were assessed at baseline, after the interventions (T0), and at 3 months follow-up (T3). Mixed modeling techniques were used for analysis.

RESULTS

Outcome in terms of discomfort and disability was generally comparable between both interventions. Catastrophizing was significantly reduced and fear-avoidance beliefs about work slightly increased after the interventions, but no consistent changes in muscle activation patterns were observed. Changes in discomfort were especially associated with changes in catastrophizing at T0 and T3, but R(2) was low (<0.14). Reduced catastrophizing at T0 and T3, and also reduced fear-avoidance beliefs about work at T3, were related to reduced disability (R(2) between 0.30 and 0.40). No differences between the two intervention groups were observed.

CONCLUSIONS

Intervention effects were generally non-specific and findings suggested that cognitive-behavioral factors underlie the outcome of these interventions rather than changes in muscle activation patterns. Emphasizing these factors during therapy may increase the beneficial outcome of occupational interventions.

Impaired functioning and quality of life in severe migraine: the role of catastrophizing and associated symptoms

Migraine characteristics are associated with impaired functioning and quality of life (Fn/QoL), but the impact of other factors on Fn/QoL in headache patients is largely unexplored. We examined catastrophizing, comorbid anxiety/depression and migraine characteristics as related to Fn/QoL, and explored the consistency of these relationships across five Fn/QoL measures. We evaluated 232 frequent migraine sufferers for comorbid psychiatric diagnosis, and they completed anxiety, depression and catastrophizing measures, recorded migraine characteristics in a diary and completed five Fn/QoL measures (four self-report questionnaires, one diary disability measure). Backward regression revealed catastrophizing and severity of associated symptoms (photophobia, phonophobia, nausea) independently predicted Fn/QoL across all five measures (beta weights 0.16-0.50, all P < 0.01). This is the first demonstration that a psychological response to migraines (catastrophizing) is associated with impaired Fn/QoL independent of migraine characteristics and other demographic and psychological variables. Severity of associated symptoms also emerged as an important contributor to Fn/QoL.

Affective pain modulation in fibromyalgia, somatoform pain disorder, back pain, and healthy controls

Previous research suggested that patients with fibromyalgia (FM) experience a higher pain intensity (clinical pain) than do patients with musculoskeletal pain after negative emotional priming compared to positive priming. To further examine affective pain modulation in FM, we applied an experimental pain induction to compare 30 patients with FM with 30 healthy (pain-free) participants (HC), and 30 patients with back pain (BP). For another group of 30 patients with somatoform pain disorder (SF), we predicted the same pain modulation as for FM. As primes we presented positive, neutral, negative, and pain-related pictures and assessed pain intensity in response to a fixed pressure weight. Overall, picture valence modulated pain intensities (in the order of pain-related > negative pictures > neutral), but the pain intensities between neutral and positive pictures did not differ significantly. SF reported significantly higher pain intensities than did BP and HC; FM were in between, but did not differ significantly from the three other groups. There was no interaction of priming and group. Affective modulation of pain was not specifically altered in FM and SF, but SF were more sensitive to pressure pain than BP and HC.

Violence, stress, and somatic syndromes

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

Striatal grey matter increase in patients suffering from fibromyalgia--a voxel-based morphometry study

Fibromyalgia (FM), among other chronic pain syndromes, such as chronic tension type headache and atypical face pain, is classified as a so-called dysfunctional pain syndrome. Patients with fibromyalgia suffer from widespread, "deep" muscle pain and often report concomitant depressive episodes, fatigue and cognitive deficits. Clear evidence for structural abnormalities within the muscles or soft tissue of fibromyalgia patients is lacking. There is growing evidence that clinical pain in fibromyalgia has to be understood in terms of pathological activity of central structures involved in nociception. We applied MR-imaging and voxel-based morphometry, to determine whether fibromyalgia is associated with altered local brain morphology. We investigated 20 patients with the diagnosis of primary fibromyalgia and 22 healthy controls. VBM revealed a conspicuous pattern of altered brain morphology in the right superior temporal gyrus (decrease in grey matter), the left posterior thalamus (decrease in grey matter), in the left orbitofrontal cortex (increase in grey matter), left cerebellum (increase in grey matter) and in the striatum bilaterally (increase in grey matter). Our data suggest that fibromyalgia is associated with structural changes in the CNS of patients suffering from this chronic pain disorder. They might reflect either a consequence of chronic nociceptive input or they might be causative to the pathogenesis of fibromyalgia. The affected areas are known to be both, part of the somatosensory system and part of the motor system.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Somatic focus/awareness: Relationship to negative affect and pain in chronic pain patients

Somatic focus refers to the tendency to notice and report physical symptoms, and has been investigated in relation to chronically painful conditions. This study investigated the relationship between somatic focus, as measured by the Pennebaker Inventory of Limbic Languidness (PILL), negative affect and pain. A secondary purpose of the present study was to examine sex differences in these relationships. Participants included 280 chronic pain patients (69.6% females, 88.9% Caucasian), who completed a battery of self-report measures on somatic focus, pain, negative affect, coping, and dysfunction. Results for the overall sample revealed that the PILL shares considerable variance with measures of negative affect, particularly with the physiological components of anxiety and depression. When the results were analyzed separately for male and female patients, it was found that several components of negative affect and cognitive factors play a stronger role in predicting somatic focus among men compared to women. Additional analyses then examined whether somatic focus was predictive of male and female patients' pain reports. Results indicated that somatic focus explained a small, but unique amount of variance in female patients' pain reports, which differed from the relationship observed among male patients.

Physical medicine rehabilitation approach to pain

A physical medicine and rehabilitation approach to acute and chronic pain syndromes includes a wide spectrum of treatment focus. Whether assessing or treating acute or chronic pain syndromes, management should include a biopsychosocial approach. Assessment may include a focused joint and functional examination including more global areas of impairment (ie, gait, balance, and endurance) and disability. More complicated multidimensional chronic pain conditions may require the use of a more collaborative continuum of multidisciplinary and interdisciplinary treatment approaches. Regardless of the scope of care that each individual patient requires, treatment options may include active physical therapy, rational polypharmacy, CBT, and the use of passive modalities. Treatment goals generally emphasize achieving analgesia, improving psychosocial functioning, and reintegration of recreational or leisure pursuits (ie, community activities and sports). Progress in all therapies necessitates close monitoring by the health care provider and necessitates ongoing communication between members of the treatment team. Although this article focuses on diagnoses related to acute and chronic low back pain, OA, and musculoskeletal disorders, assessment and treatment recommendations may be generalized to most other pain conditions.

Antidepressants in the treatment of fibromyalgia

Fibromyalgia syndrome is a chronic disease of widespread and debilitating pain whose cause is unknown and whose risk factors are poorly understood. It is often comorbid with rheumatoid and other pain disorders as well as psychiatric disorders such as anxiety and depression. Although they are not officially approved for this indication, antiepileptics and antidepressants are often used to treat fibromyalgia. The tricyclic antidepressants (TCAs), particularly amitriptyline, are among the most common treatment strategies. Because of the poor tolerability of the tricyclics, the newer antidepressants have been widely tested in fibromyalgia. The selective serotonin reuptake inhibitors (SSRIs) and the reversible monoamine oxidase inhibitors do not seem to be particularly helpful. The serotonin and norepinephrine reuptake inhibitors (SNRIs), duloxetine and milnacipran, on the other hand, have been shown in placebo-controlled trials to offer significant relief to patients suffering from fibromyalgia. Although no direct comparative studies have been performed, these compounds appear to be as effective as the TCAs but much better tolerated. The effectiveness of the SNRIs as well as other dual acting antidepressants, such as mirtazapine, but not the SSRIs, implies that a dysfunction of both serotonin and norepinephrine neurotransmission probably exists in fibromyalgia. The effectiveness of antidepressants appears to be independent of their effect on comorbid depression.

Central sensitization: a biopsychosocial explanation for chronic widespread pain in patients with fibromyalgia and chronic fatigue syndrome

In addition to the debilitating fatigue, the majority of patients with chronic fatigue syndrome (CFS) experience chronic widespread pain. These pain complaints show the greatest overlap between CFS and fibromyalgia (FM). Although the literature provides evidence for central sensitization as cause for the musculoskeletal pain in FM, in CFS this evidence is currently lacking, despite the observed similarities in both diseases. The knowledge concerning the physiological mechanism of central sensitization, the pathophysiology and the pain processing in FM, and the knowledge on the pathophysiology of CFS lead to the hypothesis that central sensitization is also responsible for the sustaining pain complaints in CFS. This hypothesis is based on the hyperalgesia and allodynia reported in CFS, on the elevated concentrations of nitric oxide presented in the blood of CFS patients, on the typical personality styles seen in CFS and on the brain abnormalities shown on brain images. To examine the present hypothesis more research is required. Further investigations could use similar protocols to those already used in studies on pain in FM like, for example, studies on temporal summation, spatial summation, the role of psychosocial aspects in chronic pain, etc.

At the crossroads between tension-type headache and fibromyalgia

Fibromyalgia syndrome and tension-type headache have multiple clinical features in common, and pathogenic mechanisms partly overlap. Significant differences need to be recognized as well. Studying the correlations of these often comorbid conditions represents a unique opportunity to gain insight into their pathophysiology and that of other chronic pain syndromes, to increase the accuracy of their diagnosis, and to improve the therapeutic armamentarium.

Pain-related Catastrophizing in Healthy Women Is Associated With Greater Temporal Summation of and Reduced Habituation to Thermal Pain

OBJECTIVE

Pain-related coping strategies, especially catastrophizing, play an influential role in shaping pain responses. However, although numerous studies have examined the impact of catastrophizing on chronic pain outcomes, relatively few have evaluated relationships between individual differences in pain-related catastrophizing and pain perception, with most of those studies examining only pain threshold or pain tolerance. We assessed, for the first time, catastrophizing's association with the magnitude of temporal summation of pain, a primary marker for central nervous system sensitizability.

METHODS

Thirty-eight healthy young women underwent standardized experimental pain testing, followed by administration of a brief questionnaire that assessed catastrophizing cognitions during the pain-testing session.

RESULTS

Higher levels of pain-related catastrophizing were related to higher suprathreshold pain ratings and greater temporal summation of thermal pain, suggesting that catastrophizing may play a facilitatory role in the processing of pain-related information, though the specific pathways underlying this facilitation are not clear.

CONCLUSIONS

These preliminary findings highlight the importance of coping in shaping individuals' responses to noxious stimuli, and suggest that interventions that decrease pain catastrophizing may reduce the burden of acute and chronic pain.