Motor Dysfunctions in Fibromyalgia Patients: The Importance of Breathing

The classification of fibromyalgia (FM) is not always immediate and simple, with the time from the first diagnosis, compared to the onset of symptoms, of a few years. Currently, we do not have instrumental or biochemical tests considered as gold standards; the clinician will make a diagnosis of FM based on the patient's medical history and subjective assessment. The symptoms can involve physical, cognitive and psychological disorders, with the presence of pain of different origins and classifications: nociplastic, nociceptive and neuropathic pain. Among the symptoms highlighted, postural disorders and neuromotor uncoordination emerge, whose functional dysfunctions can increase the mortality and morbidity rate. An alteration of the diaphragm muscle could generate such functional motor problems. Considering that the current literature underestimates the importance of breathing in FM, the article aims to highlight the relationship between motor and diaphragmatic difficulties in the patient, soliciting new points of view for the clinical and therapeutic framework.

Temporomandibular Disorders and Fibromyalgia Prevalence: A Systematic Review and Meta-Analysis

PURPOSE

To evaluate the prevalence of chronic widespread pain (CWP) and fibromyalgia syndrome (FMS) in TMD patients and the prevalence of TMDs in patients with FMS.

METHOD

A systematic search was performed in electronic databases. Studies published in English examining the prevalence of comorbid TMDs and CWP/FMS were included. The Newcastle-Ottawa Scale was used to assess study quality, and meta-analyses using defined diagnostic criteria were conducted to generate pooled prevalence estimates.

RESULTS

Nineteen studies of moderate to high quality met the selection criteria. Meta-analyses yielded a pooled prevalence rate (95% CI) for TMDs in FMS patients of 76.8% (69.5% to 83.3%). Myogenous TMDs were more prevalent in FMS patients (63.1%, 47.7% to 77.3%) than disc displacement disorders (24.2%, 19.4% to 39.5%), while a little over 40% of FMS patients had comorbid inflammatory degenerative TMDs (41.8%, 21.9% to 63.2%). Almost a third of individuals (32.7%, 4.5% to 71.0%) with TMDs had comorbid FMS, while estimates of comorbid CWP across studies ranged from 30% to 76%.

CONCLUSIONS

Despite variable prevalence rates among the included studies, the present review suggests that TMDs and CWP/FMS frequently coexist, especially for individuals with painful myogenous TMDs. The clinical, pathophysiologic, and therapeutic aspects of this association are important for tailoring appropriate treatment strategies.

How a group-based occupational therapy program works in woman with fibromyalgia: A process evaluation of the ADAPT program

BACKGROUND

The ADAPT Program have improved activities of daily living (ADL) in women with fibromyalgia. To understand the functioning of the program, it is relevant to evaluate how program theory components are linked to outcomes (mechanisms) and how the randomised controlled trial (RCT) context, influenced delivery and outcomes.

OBJECTIVE

To evaluate ADAPT in terms of dose, mechanisms of change and contextual factors.

MATERIAL/METHODS

Dose was recorded on the n = 21 participants receiving ADAPT in the IMPROvE trial (NCT01352052). A subsample of n = 16 attended one of three 2-hour focusgroups, evaluating mechanisms of change and contextual factors. Interview questions explored participants' interaction with four program components, i.e. how the 'client-centred approach', 'group-based peer-exchange format', 'teaching-learning strategies' and 'long-term program format' triggered mechanisms facilitating/hindering outcomes. Moreover, how randomisation procedures influenced delivery and outcomes.

RESULTS

Attending a long-term educational peer-exchange program, in which participants experienced met by a health professional that legitimised difficulties, facilitated participants knowledge, insights and motivation for changing habits. With time and support, participants experienced increased acceptance of their situation and began to implement more effective ways to perform ADL tasks.

CONCLUSIONS/SIGNIFICANCE

Results support previous findings of improved ADL ability post-ADAPT and provide initial evidence to support the ADAPT Program theory.

TRPA1 rare variants in chronic neuropathic and nociplastic pain patients

Supplemental Digital Content is Available in the Text.

TRPA1 gene is significantly enriched of rare variants in neuropathic pain and fibromyalgia patients, with itch or cold-induced pain as the most common features, opening new treatment opportunities.

Missing aspects of the heritability of chronic neuropathic pain, as a complex adult-onset trait, may be hidden within rare variants with low effect on disease risk, unlikely to be resolved by a single-variant approach. To identify new risk genes, we performed a next-generation sequencing of 107 pain genes and collapsed the rare variants through gene-wise aggregation analysis. The optimal unified sequence kernel association test was applied to 169 patients with painful neuropathy, 223 patients with nociplastic pain (82 diagnosed with chronic widespread pain and 141 with fibromyalgia), and 216 healthy controls. Frequency and features of variants in TRPA1 , which was the most significant gene, were further validated in 2 independent cohorts of 140 patients with chronic pain (90 with painful neuropathy and 50 with chronic widespread pain) and 34 with painless neuropathy. The effect of aminoacidic changes were modeled in silico according to physicochemical characteristics. TRPA1 was significantly enriched of rare variants which significantly discriminated chronic pain patients from healthy controls after Bonferroni correction (P = 6.7 × 10−4, ρ = 1), giving a risk of 4.8-fold higher based on the simple burden test (P = 0.0015, OR = 4.8). Among the 32 patients harboring TRPA1 variants, 24 (75%) were diagnosed with nociplastic pain, either fibromyalgia (12; 37.5%) or chronic widespread pain (12; 37.5%), whereas 8 (25%) with painful neuropathy. Irrespective of the clinical diagnosis, 12 patients (38%) complained of itch and 10 (31.3%) of cold-induced or cold-accentuated pain, mostly episodic. Our study widens the spectrum of channelopathy-related chronic pain disorders and contributes to bridging the gap between phenotype and targeted therapies based on patients' molecular profile.

1_tzjjvsic Kaltura

The natural history of chronic widespread pain in patients with axial spondyloarthritis: a cohort study with clinical and self-tracking data

OBJECTIVES

This study investigates longitudinal patterns, predictors and long-term impact of pain in axial spondyloarthritis (axSpA), using clinical and self-tracking data.

METHODS

The presence of multisite pain (MSP), affecting at least six of nine body regions using a Margolis pain drawing, and subsequent chronic widespread pain (CWP), MSP at more than one timepoint, was assessed in a cohort of axSpA patients. Incident MSP (MSP at two consecutive visits or more), intermittent MSP (MSP at two or more non-consecutive visits) and persistent MSP (MSP at each visit) were described. Demographic, clinical and self-tracking measures were compared for the CWP vs non-CWP groups using Students t test, Wilcoxon-Mann-Whitney and χ2 test for normal, non-normal and categorical data, respectively. Predictors of CWP were evaluated using logistic regression modelling.

RESULTS

A total of 136 patients, mean clinical study duration of 120 weeks (range 27-277 weeks) were included, with sufficient self-tracking data in 97 patients. Sixty-eight (50%) patients reported MSP during at least one clinical visit: eight (6%) incident MSP; 16 (12%) persistent MSP; and 44 (32%) intermittent MSP. Forty-six (34%) of the cohort had CWP. All baseline measures of disease activity, function, quality of life, sleep disturbance, fatigue and overall activity impairment were significant predictors of the development of CWP. BASDAI and BASFI scores were significantly higher in those with CWP and self-tracking data revealed significantly worse pain, fatigue, sleep quality and stress.

CONCLUSIONS

The development of CWP is predicted by higher levels of disease activity and burden at baseline. It also impacts future disease activity and wellbeing.

Heme-Induced Macrophage Phenotype Switching and Impaired Endogenous Opioid Homeostasis Correlate with Chronic Widespread Pain in HIV

Chronic widespread pain (CWP) is associated with a high rate of disability and decreased quality of life in people with HIV-1 (PWH). We previously showed that PWH with CWP have increased hemolysis and elevated plasma levels of cell-free heme, which correlate with low endogenous opioid levels in leukocytes. Further, we demonstrated that cell-free heme impairs β-endorphin synthesis/release from leukocytes. However, the cellular mechanisms by which heme dampens β-endorphin production are inconclusive. The current hypothesis is that heme-dependent TLR4 activation and macrophage polarization to the M1 phenotype mediate this phenomenon. Our novel findings showed that PWH with CWP have elevated M1-specific macrophage chemokines (ENA-78, GRO-α, and IP-10) in plasma. In vitro, hemin-induced polarization of M0 and M2 macrophages to the M1 phenotype with low β-endorphins was mitigated by treating cells with the TLR4 inhibitor, TAK-242. Similarly, in vivo phenylhydrazine hydrochloride (PHZ), an inducer of hemolysis, injected into C57Bl/6 mice increased the M1/M2 cell ratio and reduced β-endorphin levels. However, treating these animals with the heme-scavenging protein hemopexin (Hx) or TAK-242 reduced the M1/M2 ratio and increased β-endorphins. Furthermore, Hx attenuated heme-induced mechanical, heat, and cold hypersensitivity, while TAK-242 abrogated hypersensitivity to mechanical and heat stimuli. Overall, these results suggest that heme-mediated TLR4 activation and M1 polarization of macrophages correlate with impaired endogenous opioid homeostasis and hypersensitivity in people with HIV.

High Heme and Low Heme Oxygenase-1 Are Associated with Mast Cell Activation/Degranulation in HIV-Induced Chronic Widespread Pain

An overwhelming number of people with HIV (PWH) experience chronic widespread pain (CWP) throughout their lifetimes. Previously, we demonstrated that PWH with CWP have increased hemolysis and attenuated heme oxygenase 1 (HO-1) levels. HO-1 degrades reactive, cell-free heme into antioxidants like biliverdin and carbon monoxide (CO). We found that high heme or low HO-1 caused hyperalgesia in animals, likely through multiple mechanisms. In this study, we hypothesized that high heme or low HO-1 caused mast cell activation/degranulation, resulting in the release of pain mediators like histamine and bradykinin. PWH who self-report CWP were recruited from the University of Alabama at Birmingham HIV clinic. Animal models included HO-1-/- mice and hemolytic mice, where C57BL/6 mice were injected intraperitoneally with phenylhydrazine hydrochloride (PHZ). Results demonstrated that plasma histamine and bradykinin were elevated in PWH with CWP. These pain mediators were also high in HO-1-/- mice and in hemolytic mice. Both in vivo and in vitro (RBL-2H3 mast cells), heme-induced mast cell degranulation was inhibited by treatment with CORM-A1, a CO donor. CORM-A1 also attenuated mechanical and thermal (cold) allodynia in hemolytic mice. Together, the data suggest that mast cell activation secondary to high heme or low HO-1 seen in cells and animals correlates with elevated plasma levels of heme, histamine, and bradykinin in PWH with CWP.

Penalized optimal scaling for ordinal variables with an application to international classification of functioning core sets

Ordinal data occur frequently in the social sciences. When applying principal component analysis (PCA), however, those data are often treated as numeric, implying linear relationships between the variables at hand; alternatively, non-linear PCA is applied where the obtained quantifications are sometimes hard to interpret. Non-linear PCA for categorical data, also called optimal scoring/scaling, constructs new variables by assigning numerical values to categories such that the proportion of variance in those new variables that is explained by a predefined number of principal components (PCs) is maximized. We propose a penalized version of non-linear PCA for ordinal variables that is a smoothed intermediate between standard PCA on category labels and non-linear PCA as used so far. The new approach is by no means limited to monotonic effects and offers both better interpretability of the non-linear transformation of the category labels and better performance on validation data than unpenalized non-linear PCA and/or standard linear PCA. In particular, an application of penalized optimal scaling to ordinal data as given with the International Classification of Functioning, Disability and Health (ICF) is provided.

Correlation between the Altered Gut Microbiome and Lifestyle Interventions in Chronic Widespread Pain Patients: A Systematic Review

Background: Lifestyle interventions have a direct impact on the gut microbiome, changing its composition and functioning. This opens an innovative way for new therapeutic opportunities for chronic widespread patients. Purpose: The goal of the present study was to evaluate a correlation between lifestyle interventions and the gut microbiome in patients with chronic widespread pain (CWP). Methods: The systematic review was conducted until January 2023. Pain and microbiome were the two keywords selected for this revision. The search was conducted in PubMed, Chochrane, PEDro and ScienceDirect, where 3917 papers were obtained. Clinical trials with lifestyle intervention in CWP patients were selected. Furthermore, these papers had to be related with the gut microbiome, excluding articles related to other types of microbiomes. Results: Only six articles were selected under the eligibility criteria. Lifestyle interventions were exercise, electroacupuncture and ingesting a probiotic. Conclusions: Lifestyle intervention could be a suitable choice to improve the gut microbiome. This fact could be extrapolated into a better quality of life and lesser levels of pain.

The association between age at menarche and chronic pain outcomes in women: the Tromsø Study, 2007 to 2016

ABSTRACT

Sex differences in chronic pain are well established with documented predominance in women. This study assessed relationships between age at menarche and chronic pain, site-specific chronic pain, pain characteristics, and chronic widespread pain (CWP). We used data from the Tromsø Study conducted in 2007 to 2008 and 2015 to 2016 (Tromsø 6 and Tromsø 7 waves) including participants aged 30 to 99 years. The associations between age at menarche and chronic pain were examined in Tromsø 6 (n = 6449), Tromsø 7 (n = 5681), and the combination of Tromsø 6 and Tromsø 7 (n = 12,130). Tromsø 7 data were used further to examine the associations between age at menarche and site-specific chronic pain, 4 pain characteristics (pain duration, pain intensity, episode duration, and episode frequency), and CWP. All analyses were adjusted for body mass index, age, and economic status of the household in childhood. Lower age at menarche was associated with an increased risk of chronic pain in all 3 samples (risk ratio for each year delay in menarche 0.98, 95% CI [0.97 to 0.99] across samples). Risk differences were -0.014, CI 95% (-0.02 to -0.005) in Tromsø 6, -0.011, CI 95% (-0.02 to -0.02) in Tromsø 7, and -0.012, CI 95% (-0.02 to -0.01) in the combined sample. Age at menarche was significantly associated with chronic pain in the neck, abdomen, and both arms, and CWP. Of the 4 pain characteristics, pain duration was statistically significant. We conclude that early menarche is an independent risk factor for pain across a broad spectrum of pain outcomes.

Person-centred health plans for physical activity in persons with chronic widespread pain (CWP) - a retrospective descriptive review

PURPOSE

Physical activity is recommended as first-choice treatment in chronic pain conditions. The aim was to describe the content and perceptions of person-centred health plans, and to evaluate patients' implementation of the health plan in their everyday life.

MATERIALS AND METHODS

A descriptive retrospective review was conducted of person-centred health plans to support physical activity in 133 participants. Quantitative content analysis was used to analyse the content of the health plans. Questionnaires on physical activity and on implementation and perception of the health plans, and a test of physical capacity were administered.

RESULTS

Participants' goals were found to be related to physical function (n = 118), general health (n = 90), activity and participation (n = 80) and symptoms (n = 35). Participants identified personal (n = 174), social (n = 69) and material resources (n = 36). They identified fears and obstacles related to health issues (n = 95), difficulties getting it done (n = 41), competing priorities (n = 19) and contextual factors (n = 12). Participants identified need for external support (n = 110). Participants' level of physical activity and physical capacity increased significantly during the first 6 months of the study.

CONCLUSION

The person-centred approach seems helpful in enhancing motivation to achieve set goals and strengthen self-efficacy in physical activity also supported by increased physical activity and physical capacity. Implications for rehabilitationA person-centred approach can be helpful to enhance motivation to achieve set goals and self-efficacy to manage symptoms when engaging in physical activity.Shared documentation of a personal health plan helps to visualize resources to promote regular physical activity as well as alternative ways to reach set goals.The co-created health-plan captures the participant's goals, resources, fears and need of support, helps the participant to overcome challenges, and supports the participant to be physically active.

Facing Invalidation: A Further Challenge when Living with Chronic Widespread Pain

OBJECTIVE

The concept of "invalidation" refers to the patient's perception that the social environment does not recognize their medical condition. This study explores and describes invalidation experiences among Swedish patients with chronic widespread pain with regard to sociodemographic and pain characteristics, impact of pain, self-reported health, and symptoms of anxiety and depressive.

METHODS

A cross-sectional design using questionnaires, including sociodemographic and pain variables, the Illness Invalidation Inventory (Likert scale items regarding 5 sources), the Hospital Anxiety and Depression Scale, and the Short-Form General Health Survey. Descriptive and univariate analyses were applied.

RESULTS

Of the 152 respondents, 91% were women. Swedish patients with chronic widespread pain experienced invalidation to a large extent from all sources. The highest scores for invalidation were reported from contacts with social services (68%), and the lowest from spouses (30%). Being younger (p < 0.006), having periodic pain (p = 0.011), and having had more frequent visits to a doctor in the previous year (p = 0.007) were characteristics associated with higher invalidation scores. Experiences of invalidation were associated with worse selfreported mental health scores (r = -0.29 to -0.46).

CONCLUSION

Since patients with chronic widespread pain frequently experience invalidation from the social environment, this further challenge in daily life must be taken into consideration in pain management within multimodal pain rehabilitation.

An association between chronic widespread pain and the gut microbiome

OBJECTIVES

Chronic widespread musculoskeletal pain (CWP) is a characteristic symptom of fibromyalgia, which has been shown to be associated with an altered gut microbiome. Microbiome studies to date have not examined the milder CWP phenotype specifically nor have they explored the role of raised BMI. The aim of this study was to investigate whether the microbiome is abnormal in CWP.

METHODS

CWP was assessed using a standardized screening questionnaire in female volunteers from the TwinsUK cohort including 113 CWP cases and 1623 controls. The stool microbiome was characterized using 16S rRNA amplicon sequencing and amplicon sequence variants, and associations with CWP examined using linear mixed-effects models adjusting for BMI, age, diet, family relatedness and technical factors.

RESULTS

Alpha diversity was significantly lower in CWP cases than controls (Mann-Whitney test, P-values 2.3e-04 and 1.2e-02, for Shannon and Simpson indices respectively). The species Coprococcus comes was significantly depleted in CWP cases (Padj = 3.04e-03). A genome-wide association study (GWAS) performed for C. comes in TwinsUK followed by meta-analysis with three Dutch cohorts (total n = 3521) resulted in nine suggestive regions, with the most convincing on chromosome 4 near the TRAM1L1 gene (rs76957229, P = 7.4e-8). A Mendelian randomization study based on the results of the GWAS did not support a causal role for C. comes on the development of CWP.

CONCLUSIONS

We have demonstrated reduced diversity in the microbiome in CWP, indicating an involvement of the gut microbiota in CWP; prospectively the microbiome may offer therapeutic opportunities for this condition.

Women with Fibromyalgia Prefer Resistance Exercise with Heavy Loads-A Randomized Crossover Pilot Study

Fibromyalgia (FM) is a chronic pain condition associated with impaired muscle strength and exercise-induced pain. Physical exercise has been highlighted, by international clinical guidelines and stakeholders, as an essential component of rehabilitation in FM. Exposure to pain during exercise is generally correlated with elevated lactate levels and, additionally, is one known reason for persons with FM to avoid physical exercise and activity. A crossover design was used to test and evaluate an approach consisting of resistance exercise with heavy loads and a low number of repetitions among ten women with FM. The participants were consecutively recruited to test and perform exercise with two different resistance levels (A = light/moderate load, and B = heavy load) in a randomized crossover trial using an AB/BA setting. Results showed that the heavy load exercise session was experienced as more positive than the light/moderate load exercise session and that lower lactate levels followed exercise with heavier weight loads. This is promising and indicates that the approach of heavy weight loads and accustomed repetitions is accepted in FM and has the potential to attenuate hesitation to exercise due to exercise-induced pain. However, these effects need to be further investigated in more extensive studies.

Chronic Pain in HIV

The evolution of therapeutics for and management of human immunodeficiency virus-1 (HIV-1) infection has shifted it from predominately manifesting as a severe, acute disease with high mortality to a chronic, controlled infection with a near typical life expectancy. However, despite extensive use of highly active antiretroviral therapy, the prevalence of chronic widespread pain in people with HIV remains high even in those with a low viral load and high CD4 count. Chronic widespread pain is a common comorbidity of HIV infection and is associated with decreased quality of life and a high rate of disability. Chronic pain in people with HIV is multifactorial and influenced by HIV-induced peripheral neuropathy, drug-induced peripheral neuropathy, and chronic inflammation. The specific mechanisms underlying these three broad categories that contribute to chronic widespread pain are not well understood, hindering the development and application of pharmacological and nonpharmacological approaches to mitigate chronic widespread pain. The consequent insufficiencies in clinical approaches to alleviation of chronic pain in people with HIV contribute to an overreliance on opioids and alarming rise in active addiction and overdose. This article reviews the current understanding of the pathogenesis of chronic widespread pain in people with HIV and identifies potential biomarkers and therapeutic targets to mitigate it.

Long-term trajectories of chronic musculoskeletal pain: a 21-year prospective cohort latent class analysis

ABSTRACT

Our knowledge of the prevalence, impact, and outcomes of chronic pain in the general population is predominantly based on studies over relatively short periods of time. The aim of this study was to identify and describe trajectories of the chronic pain status over a period of 21 years. Self-reported population data (n = 1858) from 5 timepoints were analyzed. Pain was categorized by: no chronic pain (NCP), chronic regional pain (CRP), and chronic widespread pain (CWP). Latent class growth analysis was performed for identification of trajectories and logistic regression analysis for identification of predictors for pain prognosis. Five trajectories were identified: (1) persistent NCP (57%), (2) migrating from NCP to CRP or CWP (5%), (3) persistent CRP or migration between CRP and NCP (22%), (4) migration from CRP to CWP (10%), and (5) persistent CWP (6%). Age, sleeping problems, poor vitality, and physical function at baseline were associated with pain progression from NCP. Female gender, seeking care for pain, lack of social support, poor physical function, vitality, and mental health predicted poor pain prognosis among those with CRP. In conclusion, chronic pain was common in the population including 6% reporting persistent CWP, although the majority persistently reported NCP. Most people had stable pain status, but some had ongoing change in pain status over time including people who improved from chronic pain. It was possible to identify clinically relevant factors, characterizing trajectories of chronic pain development, that can be useful for identifying individuals at risk and potential targets for intervention.

Brain-Derived Neurotrophic Factor and Immune Cells in Osteoarthritis, Chronic Low Back Pain, and Chronic Widespread Pain Patients: Association with Anxiety and Depression

Background and Objectives: Musculoskeletal dysfunction can induce several types of chronic pain syndromes. It is of particular interest to elucidate the pathomechanism of different forms of chronic pain. It is possible that patients who have developed chronic widespread pain (CWP) may endure different pathomechanisms as compared to those who suffer from local pain (osteoarthritis, OA) and regional pain (chronic low back pain, cLBP), especially with regard to pain regulation and its related biomediators. The aim of this study was to determine the differences in pathomechanisms among these patients by measuring pain-related biomediators, particularly brain-derived neurotrophic factor (BDNF). Additionally, subpopulations of immune cells were determined in parallel. Materials and Methods: Patients and healthy subjects (HSs) were recruited (age and gender-matched). BDNF was measured from serum samples of patients and HSs and the data of body composition parameters were recorded. Additionally, both patients and HSs were asked to fill in questionnaires related to pain intensity, anxiety, and depression. Results: Our results highlight that the levels of both free and total BDNF are significantly lower in pain patients compared to HSs, with p values of 0.041 and 0.024, respectively. The number of CD3- CD56bright natural killer (NK) cells shows significant differences between the groups. Comparing all chronic pain patients with HSs reveals a significantly lower number of CD4+ CD8+ T cells (p = 0.031), CD3- CD56bright NK cells (p = 0.049) and CD20+ CD3- cells (p = 0.007). Conclusions: To conclude, it seems that a general conformity between the pathomechanisms of different chronic pain diseases exists, although there are unique findings only in specific chronic pain patients.

Assessing our approach to diagnosing Fibromyalgia

Introduction: Fibromyalgia represents the most prevalent of the group of conditions that are known as central sensitivity syndromes. Approximately 2-5% of the adult population in the United States is affected by Fibromyalgia. This pain amplification syndrome has an enormous economic impact as measured by work absenteeism, decreased work productivity, disability and injury compensation, and over-utilization of healthcare resources. Multiple studies have shown that early diagnosis of this condition can improve patient outlook, and redirect valuable health care resources toward more appropriate targeted therapy. Efforts have been made toward improving diagnostic accuracy through updated criteria. Areas Covered: Reviewed here are 1) reasons for the need for more accurate diagnosis of Fibromyalgia, (2) a review of the evolution of Fibromyalgia to current times, and (3) the proliferation of currently available diagnostic criteria and problems related to each of them. From initial literature review until October 2020, PubMed, Embase, and Scopus were searched for applicable literature. Expert Opinion: A discussion of ongoing efforts to obtain a biomarker to enhance diagnostic accuracy concludes this review. A need to include rheumatologists as part of the care team of patients with Fibromyalgia is emphasized.

Non-specific analgesia during a clinical trial in fibromyalgia

BACKGROUND

When patients suffering from fibromyalgia undergo a therapeutic trial, a non-negligible part of analgesia is not explained by the drug itself. The mechanisms of this non-specific effect need to be understood.

MATERIALS AND METHODS

We undertook secondary analyses of a double-blind randomized trial in fibromyalgia patients in which 100 mg/day milnacipran was not found superior to placebo. Data from 49 patients belonging to both groups were pooled. Both before treatment and one month after treatment, all patients underwent a CaNTAB^® neuropsychological test (related to spatial planning, reaction time, decision-making and risk-taking, and ability to name objects), and measurements of sensation and pain thresholds to heat and cold, supraliminal heat pain threshold, punctuate mechanical pain threshold and temporal summation, mechanical allodynia to skin brushing, and response to conditioned pain modulation. We studied the baseline predictors of analgesia and the indicators of change associated to analgesia separately. A stepwise approach was used to select the factors to enter into the final ANCOVAs, in which age, body mass index, treatment group and pain at baseline were covariates.

RESULTS

No baseline predictor of non-specific analgesia other than pain at baseline was found to be predictive. Conversely, several neuropsychological (higher performance) or psychophysical (lower sensitivity) changes correlated with analgesia in unadjusted analyses. Multivariable analyses identified increases in warm/heat thermal thresholds and an increased ability to name objects, as factors associated with analgesia.

CONCLUSIONS

The changes observed concomitantly to non-specific pain analgesia might be related to mild changes in brain functioning, based on convergent literature data.

Factors Associated With Sleep Quality in Patients With Chronic Widespread Pain Attending Multidisciplinary Treatment

PURPOSE

(1) To investigate the prevalence of poor sleep quality and (2) to explore the associations between clinical, cognitive, and emotional factors and quality of sleep in patients with chronic widespread pain (CWP) receiving multidisciplinary treatment.

METHOD

Baseline data were used from 163 patients with CWP referred for multidisciplinary treatment. Linear regression models were used to assess the relationship of clinical (pain, fatigue, pain interference, and disability), emotional (anxiety, depression, and psychological distress), and cognitive factors (catastrophizing, acceptance, self-efficacy, kinesiophobia and illness beliefs) with sleep quality, as measured using the Pittsburgh Sleep Quality Index.

RESULTS

Poor sleep quality was found in 92% of the patients. The multivariable model showed that a higher level of fatigue (b = 1.77, standard error [SE] = 0.62, β = 0.21, t = 2.87, P < 0.01), psychological distress (b = 0.02, SE = 0.01, β = 0.27, t = 3.50, P < 0.01), and more concerns about the illness (b = 0.46, SE = 0.18, β = 0.20, t = 2.57, P = 0.01) were independently associated with poorer quality of sleep. The overall linear regression model explains 27.9% of sleep quality.

CONCLUSIONS

The high prevalence of poor sleep quality in patients with CWP referred for multidisciplinary treatment emphasizes the need to target sleep during treatment. Further research is needed to disentangle the cause-effect relationship between fatigue, psychological distress, and concerns about the illness and poor sleep (note: this abstract has been published before [Ann Rheum Dis. 2018;77:A1788]).

Motivational Non-directive Resonance Breathing as a Treatment for Chronic Widespread Pain

Chronic widespread pain (CWP) is one of the most difficult pain conditions to treat due to an unknown etiology and a lack of innovative treatment design and effectiveness. Based upon preliminary findings within the fields of motivational psychology, integrative neuroscience, diaphragmatic breathing, and vagal nerve stimulation, we propose a new treatment intervention, motivational non-directive (ND) resonance breathing, as a means of reducing pain and suffering in patients with CWP. Motivational ND resonance breathing provides patients with a noninvasive means of potentially modulating five psychophysiological mechanisms imperative for endogenously treating pain and increasing overall quality of life.

Interpreting the Effectiveness of Opioids and Pregabalin for Pain Severity, Pain Interference, and Fatigue in Fibromyalgia Patients

OBJECTIVE

To evaluate the effectiveness of opioids and/or pregabalin on patient-reported outcomes among fibromyalgia (FM) patients based on levels of improvement.

METHODS

A total of 1,421 FM patients were identified, with 3,082 observational periods of opioids with or without pregabalin use between April 2008 and February 2015. Patients were categorized by opioids, and pregabalin with and without opioids; opioids were designated by morphine equivalent dose (MED) of ≤ 20 (low MED), > 20 to < 100 (moderate MED), ≥ 100 (high MED), and pregabalin doses of ≤ 150 mg, 151 to 300 mg, and 301 to 450 mg. Proportions of patients meeting clinically relevant thresholds of ≥ 30% and ≥ 50% improvement for pain interference (ability to enjoy life; activity; mood; relationships; sleep), pain severity, and fatigue were compared among treatments, and area under the curve (AUC) for improvement and worsening of effects was determined, enabling ranking of treatments. Further analysis compared pregabalin doses.

RESULTS

Pregabalin without opioids resulted in the highest proportions of patients with ≥ 30% improvement on all pain items and pain interference with "ability to enjoy life," "activity" "mood," and "sleep." For the ≥ 50% threshold, pregabalin alone was highest for all pain interference items and for "average pain" and "worst pain." Pregabalin was consistently lowest across thresholds for fatigue, but showed better results combined with moderate MED opioids. Pregabalin doses recommended for treatment of FM (151 to 450 mg) generally resulted in the highest proportion of patients achieving thresholds relative to opioids. The AUC results were consistent with thresholds; pregabalin without opioids resulted in the greatest benefits with regard to improvement, with the highest ranking for overall improvement and overall effects.

CONCLUSION

Pregabalin without opioids provided the most favorable outcomes overall based on ≥ 30% and ≥ 50% improvement thresholds and AUC, with support for moderate MED opioids + pregabalin in patients suffering from fatigue. While most patients took less than recommended pregabalin doses, higher doses may lead to improved outcomes.

Genetic Factors Explain the Association Between Pain Catastrophizing and Chronic Widespread Pain

This study aimed to clarify whether there are shared genetic and/or environmental factors explaining the strong link between pain catastrophizing (PC) and chronic widespread pain (CWP). Data were available for N = 1,109 female twins from TwinsUK. Information on self-reported CWP and PC was subject to variance component twin analysis. Heritabilities were 40% for PC and 77% for CWP. The genetic correlation between PC and CWP was .40%, whereas no evidence of an environmental correlation could be detected (.0). According to the best-fitting additive genetic, non-shared environmental (AE) Cholesky model, an additive genetic factor loading on PC as well as CWP, as well as an additive genetic factor loading on CWP alone was found. In terms of environmental influences, 2 individual environmental factors could be identified, loading separately on PC and CWP. Overall, the results add to the knowledge on the nature of CWP and the basis of its close relationship with PC by suggesting a shared genetic etiological structure. The findings highlight a potential avenue for future research and may provide useful insight for the clinical management of pain and pain coping.

PERSPECTIVE

Results suggest a shared genetic etiological structure between CWP and PC with no shared influence of environmental factors. Clinicians should be aware of this biological link within the context of clinical management of pain and pain coping.

Genetic and epigenetic epidemiology of chronic widespread pain

The etiology underlying chronic widespread pain (CWP) remains largely unknown. An integrative biopsychosocial model seems to yield the most promising explanations for the pathogenesis of the condition, with genetic factors also contributing to disease development and maintenance. Here, we conducted a search of studies investigating the genetic and epigenetic epidemiology of CWP through electronic databases including Web of Science, Medline, PubMed, EMBASE, and Google Scholar. Combinations of keywords including CWP, chronic pain, musculoskeletal pain, genetics, epigenetics, gene, twins, single-nucleotide polymorphism, genotype, and alleles were used. In the end, a total of 15 publications were considered relevant to be included in this review: eight were twin studies on CWP, six were molecular genetic studies on CWP, and one was an epigenetic study on CWP. The findings suggest genetic and unique environmental factors to contribute to CWP. Various candidates such as serotonin-related pathway genes were found to be associated with CWP and somatoform symptoms. However, studies show some limitations and need replication. The presented results for CWP could serve as a template for genetic studies on other chronic pain conditions. Ultimately, a more in-depth understanding of disease mechanisms will help with the development of more effective treatment, inform nosology, and reduce the stigma still lingering on this diagnosis.

Controversies and challenges in fibromyalgia: a review and a proposal

Fibromyalgia (FM) is the most commonly encountered chronic widespread pain (CWP) condition in rheumatology. In comparison to inflammatory arthritis (IA), it can seem ill defined with no clear understanding of the pathology and therefore no specific targeted treatment. This inevitably raises controversies and challenges. However, this is an outdated view perpetuated by poor teaching of pain at undergraduate and postgraduate levels, and the perennial problem of advances in relevant cross-speciality knowledge penetrating speciality silos. Research has provided a better understanding of the aetiopathology and FM is now regarded as a centralized pain state. Effective treatment is possible utilizing a multidisciplinary approach combining nonpharmacologic and pharmacologic treatments rooted in a biopsychosocial model. This article will provide a review of the mechanisms, diagnosis and treatment of FM, focus on some ongoing contentious issues and propose a change to the diagnostic terminology.

Family dysfunction: A comparison of chronic widespread pain and chronic localized pain

Previous studies have shown differences in the psychosocial factors related to chronic localized pain (CLP) and chronic widespread pain (CWP). However, no studies have done an evaluation of differences between CLP and CWP from the viewpoint of family functioning. We did a cross-sectional study in a tertiary care setting to investigate possible differences in the relation of CWP and CLP to family functioning.Patients with CLP (N = 126) or CWP (N = 75) were assessed for family functioning by the Family Assessment Device (FAD) and a comparison was done. Logistic regression analysis was used to estimate associations of family functioning subscales with pain status (CWP vs CLP), controlling for demographic variables, pain variables; pain duration, pain ratings, pain disability, and psychological factors; depression, anxiety, and catastrophizing. The odds ratios (ORs) for the presence of CWP were calculated.Compared to patients with CLP, patients with CWP showed a lower functional status for Roles and Affective Involvement. The ORs for CWP were significantly higher in lower functioning Roles (OR: 2.38, 95% CI: 1.21-4.65) and Affective Involvement (OR: 2.86, 95% CI: 1.56-5.24) after adjusting for demographic variables. The significant association of CWP to Roles and Affective Involvement remained after controlling for the pain variables and psychological factors.This study shows that the families of patients with CWP have poorer family functioning than those with CLP. Our findings suggest that early identification and interventions for the family dysfunction of chronic pain patients are important to the treatment and prevention of CWP.

Chronic Fatigue Syndrome and Chronic Widespread Pain in Adolescence: Population Birth Cohort Study

Although many studies have investigated the overlap between pain phenotypes and chronic fatigue syndrome (CFS) in adults, little is known about the relationship between these conditions in adolescents. The study's aim was therefore to identify whether a relationship exists between chronic widespread pain (CWP) and CFS in adolescents and investigate whether the two share common associations with a set of covariates. A questionnaire was administered to offspring of the Avon Longitudinal Study of Parents and Children (ALSPAC) at age 17, asking about site, duration, and pain intensity, from which participants with CWP were identified. At the same research clinic, a computer-based Revised Clinical Interview Schedule was filled out, from which a classification of CFS was obtained. The relationship between selected covariates and CFS and CWP was investigated using a variety of logistic, ordinal logistic, and multinomial regressions. We identified 3,214 adolescents with complete data for all outcomes and covariates. There were 82 (2.6%) individuals classified as CFS and 145 (4.5%) as CWP. A classification of CFS resulted in an increased likelihood of having CWP (odds ratio = 3.87; 95% confidence interval, 2.05-7.31). Female adolescents were approximately twice as likely to have CFS or CWP, with multinomial regression revealing a greater sex effect for CWP compared with CFS. Those with exclusive CFS were more likely to report higher levels of pain and greater effect of pain compared with those without CFS, although associations attenuated to the null after adjustment for covariates, which did not occur in those with exclusive CWP. Multinomial regression revealed that relative to having neither CFS nor CWP, a 1-unit increase in the depression and anxiety scales increased the risk of having exclusive CFS and, to a greater extent, the risk of having comorbid CFS and CWP, but not exclusive CWP, which was only related to anxiety.

PERSPECTIVE

In this cohort, 14.6% of adolescents with CFS have comorbid CWP. The likely greater proportion of more mild cases observed in this epidemiological study means that prevalence of overlap may be underestimated compared with those attending specialist services. Clinicians should be aware of the overlap between the 2 conditions and carefully consider treatment options offered.

Progression of fibromyalgia: results from a 2-year observational fibromyalgia and chronic pain study in the US

Background

A previous fibromyalgia (FM) research reports that 20%–47% of diagnosed patients may not meet the study definition of FM 1–2 years after diagnosis. The aim of this study was to gain a better understanding of the progression of FM in a geographically diverse cohort over a 2-year time period.

Methods

This cohort study followed 226 subjects recruited online to assess FM and chronic widespread pain (CWP) diagnosis stability over time. At enrollment (baseline), subjects provided informed consent, completed an online questionnaire consisting of the London Fibromyalgia Epidemiology Study Screening Questionnaire to screen for CWP (bilateral pain above/below waist lasting ≥1 week in the past 3 months), visited a site for physician evaluation for FM, and completed a questionnaire with validated patient-reported outcome instruments. Subjects were classified into mutually exclusive groups: FM+CWP+ (screened positive for CWP and received physician diagnosis of FM), FM−CWP+ (screened positive for CWP but did not receive physician diagnosis of FM), and FM−CWP− (screened negative for CWP). Approximately 2 years later (follow-up), subjects were reassessed at the same study site and completed a questionnaire with the same patient-reported outcomes.

Results

Seventy-six FM+CWP+ subjects completed assessments at both time points; 56 (73.7%) met the FM study definition at follow-up. Twenty subjects no longer met the FM study definition (eleven became FM−CWP− and nine became FM−CWP+). Ten subjects (two from FM−CWP− and eight from FM−CWP+) transitioned into the FM+CWP+ group at follow-up; they reported more tender points and pain interference with sleep and worse physical function at baseline compared with subjects who did not transition to FM+CWP+. Most (76.7%) of the subjects who transitioned into/out of FM+CWP+ experienced changes in CWP, number of positive tender points, or both.

Conclusion

The results suggest that some FM+CWP+ patients experience fluctuation in symptoms over time, which may reflect the waxing and waning nature of FM and affect diagnosis and treatment.

Specific proteins of the trapezius muscle correlate with pain intensity and sensitivity - an explorative multivariate proteomic study of the trapezius muscle in women with chronic widespread pain

Chronic widespread pain (CWP) including fibromyalgia syndrome (FMS) has a high prevalence and is associated with prominent negative consequences. CWP/FMS exhibits morphological and functional alterations in the central nervous system. The importance of peripheral factors for maintaining the central alterations are under debate. In this study, the proteins from biopsies of the trapezius muscle from 18 female CWP/FMS patients and 19 healthy female controls were analyzed. Pain intensity and pressure pain thresholds (PPT) over the trapezius muscles were registered. Twelve proteins representing five different groups of proteins were important regressors of pain intensity in CWP/FMS (R²=0.99; P<0.001). In the regression of PPT in CWP/FMS, it was found that 16 proteins representing six groups of proteins were significant regressors (R²=0.95, P<0.05). Many of the important proteins were stress and inflammation proteins, enzymes involved in metabolic pathways, and proteins associated with muscle damage, myopathies, and muscle recovery. The altered expression of these proteins may reflect both direct and indirect nociceptive/inflammatory processes as well as secondary changes. The relative importance of the identified proteins and central alterations in CWP need to be investigated in future research. Data from this and the previous study concerning the same cohorts give support to the suggestion that peripheral factors are of importance for maintaining pain aspects in CWP/FMS.

Fibroline: A mobile app for improving the quality of life of young people with fibromyalgia

Fibroline is a mobile application with a self-administered cognitive behavioral treatment for young people with fibromyalgia or chronic widespread pain, designed to reduce pain and other common negative symptoms and improve quality of life. Our aims are to report on the usability and feasibility protocols used to assess the app. Two usability cycles were implemented. A group of patients followed the cognitive behavioral treatment intervention to test its feasibility. Qualitative data were collected and content analyses were conducted. The results demonstrated that the app is error-free, easy to use, liked by the users, and acceptable.

The Effects of Forest Therapy on Coping with Chronic Widespread Pain: Physiological and Psychological Differences between Participants in a Forest Therapy Program and a Control Group

This study aimed to investigate the effects of a two-day forest therapy program on individuals with chronic widespread pain. Sixty one employees of a public organization providing building and facilities management services within the Seoul Metropolitan area participated in the study. Participants were assigned to an experimental group (n = 33) who participated in a forest therapy program or a control group (n = 28) on a non-random basis. Pre- and post-measures of heart rate variability (HRV), Natural Killer cell (NK cell) activity, self-reported pain using the visual analog scale (VAS), depression level using the Beck Depression Inventory (BDI), and health-related quality of life measures using the EuroQol Visual Analog Scale (EQ-VAS) were collected in both groups. The results showed that participants in the forest therapy group, as compared to the control group, showed physiological improvement as indicated by a significant increase in some measures of HRV and an increase in immune competence as indicated by NK cell activity. Participants in the forest therapy group also reported significant decreases in pain and depression, and a significant improvement in health-related quality of life. These results support the hypothesis that forest therapy is an effective intervention to relieve pain and associated psychological and physiological symptoms in individuals with chronic widespread pain.

The epidemiology of regional and widespread musculoskeletal pain in rural versus urban settings in those ≥55 years

OBJECTIVES

To examine whether the prevalence of regional and chronic widespread pain (CWP) varies with rurality and to determine the characteristics of persons in rural locations in whom pain is found to be in excess.

METHODS

Participants, aged ≥55 years, from participating general practices in seven different geographical locations in Scotland were sent a postal questionnaire. The 1-month prevalence of 10 regional pain conditions plus CWP was identified using body manikins. Differences in the prevalence of pain with differing rurality were examined using Chi(2) test for trend. Thereafter, among the rural population, the relationships between pain and putative risk factors were examined using Poisson regression. Thus, results are described as risk ratios.

RESULTS

There was some evidence to suggest that the prevalence of CWP increased with increasing rurality, although the magnitude of this was slight. No large or significant differences were observed with any regional pain conditions. Factors associated with the reporting of CWP included poor general health, feeling downhearted most of the time and selected measures of social contact. Factors independently associated with CWP included female gender (risk ratio: 1.24; 95% confidence interval (CI): 0.997-1.55), poor self-rated health (risk ratio: 3.50; 95% CI: 1.92-6.39) and low mood (risk ratio: 1.54; 95% CI: 1.07-2.20). Also, having fewer than 10 people to turn to in a crisis was associated with a decrease in the risk of CWP - risk ratio: 0.68 (95% CI: 0.50-0.93) and 0.78 (95% CI: 0.60-1.02) for those with 5-10 and <5 people, respectively.

CONCLUSIONS

This study provides no evidence that the prevalence of regional musculoskeletal pain is increased in rural settings, although there is some evidence of a modest increase in CWP. Risk factors for CWP are similar to those seen in the urban setting, including markers of general health, mental health and also aspects of social contact. It may be, however, that social networks are more difficult to maintain in rural settings, and clinicians should be aware of the negative effect of perceived social isolation on pain in rural areas.

Transcranial magnetic stimulation in the treatment of chronic widespread pain: a randomized controlled study

OBJECTIVE

Our objective was to assess transcranial magnetic stimulation (TMS) in the treatment of chronic widespread pain.

METHODS

Nineteen participants were randomized into 2 groups: one group receiving active TMS (n = 7) and another group receiving sham stimulation (n = 11) applied to the left dorsolateral prefrontal cortex. During sham stimulation, subjects heard a sound similar to the sound heard by those receiving the active treatment and received an active electrical stimulus to the scalp. The stimulation protocol consisted of 15 sessions completed within a 4-week period. Blind assessments were done at baseline and after each 5 sessions followed by blind assessments at 1 week, 1 month, and 3 months after the last TMS sessions. The primary outcome variable was a pain measure, the Gracely Box Intensity Scale (BIRS).

RESULTS

The percentage of subjects who guessed that they were receiving TMS was similar in the 2 groups. Both the TMS group and the sham group showed a statistically significant reduction in the BIRS scores from baseline during the acute phase of treatment and the follow-up phase. However, the TMS and sham groups did not differ in the change in the BIRS scores.

DISCUSSION

Although some previous clinical studies and basic science studies of TMS in treating pain are promising, this study found no difference in the analgesic effect of TMS and sham stimulation. Future studies should use a sham condition that attempts to simulate the sound and sensation of the TMS stimulation. Stimulus location and other stimulus parameters should be explored in future studies.

Using a profile of a modified Brief ICF Core Set for chronic widespread musculoskeletal pain with qualifiers for baseline assessment in interdisciplinary pain rehabilitation

Aim

To describe the use of a “workable” visual profile of function and disability, based on a modified Brief International Classification of Functioning, Disability and Health (ICF) Core Set for chronic widespread pain, for initial assessments in a clinical setting of interdisciplinary pain rehabilitation teams.

Method

The Brief ICF Core Set was slightly adapted to meet the needs of an interdisciplinary rehabilitation medicine team working in a university outpatient clinic and admitting patients referred from primary care. The Core Set categories were made measurable by means of eg, assessment instruments and clinical investigations. The resulting profile was given a workable shape to facilitate rapid understanding of the initial assessment outcome.

Results

Individual patients showed different profiles of problems and resources, which facilitated individual rehabilitation planning. At the level of the study group, the profiles for the Core Set component Body Functions showed that most patients had severe impairment in the sensation of pain and exercise tolerance categories of function, but most had resources in the motivation and memory categories of function. Likewise, for the component Activities, most patients had limitations in lifting and carrying objects and remunerative employment, but most had resources in intimate relationships and family relationships. At first, the use of the modified Brief ICF Core Set in the team conference was rather time consuming, but after a couple of months of experience, the team assessment took approximately 30 minutes to complete per patient.

Conclusion

The profile of the modified Brief ICF Core Set for chronic widespread pain served as a common platform, facilitating cooperation between the rehabilitation team members and providing a uniform language, which helped in structuring the clinical work. The profile also provided an easily accessible, overall view of the patient’s problems and resources, which helped in understanding the functioning situation of the patient.

Pregabalin in treatment-refractory fibromyalgia

Context:

Fibromyalgia is a chronic musculoskeletal pain disorder. The pain can be intractable and may not respond to commonly-used treatments, such as tricyclic antidepressants and opioids.

Objectives:

To evaluate pregabalin response in the subset of patients with fibromyalgia whose pain had been judged refractory to other treatments.

Methods:

Patients had previously participated in a controlled trial of pregabalin and had moderate to severe pain despite treatment with gabapentin, a tricyclic antidepressant, and a third medication (e.g., other anticonvulsants, opioid, selective serotonin reuptake inhibitors, tramadol). Flexible-dose pregabalin 150-600 mg/day was added for 3-month treatment cycles, each followed by 3- to 28-day pregabalin “drug holiday” that lasted until a relapse occurred. Pain intensity was measured using the visual analogue scale of the Short-Form McGill Pain Questionnaire completed at baseline, the end of each 3-month treatment period and at the relapse visit. Analysis was at 15 months (after 5 cycles).

Results:

In total, 25 patients were included and 19 completed the 15-month analysis period. At baseline, 88% were receiving ≥1 pain medication. Pregabalin 150-600 mg/day was associated with statistically significant, clinically meaningful pain reduction during each treatment cycle. Pain quickly returned to baseline levels during the “drug holidays” in a median time of 2-4 days. Somnolence (n=5) and dizziness (n=4) were the most common adverse events.

Conclusions:

These results suggest that pregabalin may be beneficial in patients with fibromyalgia who have had an unsatisfactory response to treatment with other medications.

Latent class analysis of functional somatic symptoms in a population-based sample of twins

OBJECTIVE

This study aimed to investigate empirically how and in what way individuals with symptoms of functional somatic syndromes should be classified. We also aimed to look into genetic and environmental influences on the classification.

METHOD

A total of 28,531 twins aged 41-64 underwent screening interviews via a computer-assisted data collection system from 1998 to 2002. Nine functional somatic symptoms (abnormal tiredness, general muscular pain, recurrent abdominal discomfort, back pain, gastroesophageal reflux, recurrent headache, recurrent urinary problem, dizziness, breathlessness at rest) were assessed using structured questions in a blinded manner. Latent class analysis was applied to the data. Structural equation modeling was further performed in order to estimate the relative importance of genetic and environmental influences on class probability.

RESULTS

Latent class analysis resulted in a five-class solution. Individuals in the first class did not show any health problems. Those assigned to the second, third, and fourth classes tended to have abnormal tiredness, gastrointestinal problems, and pain-related symptoms, respectively. Individuals in the fifth class had multiple symptoms to a greater extent than the other classes. All the five classes showed modest genetic influences (7-29% of the total variation) with gender differences except Class 3; however, the majority of influences on the class membership derived from unique environmental effects.

CONCLUSION

The findings suggested the necessity of redefining the existing classification criteria for functional somatic syndromes in terms of single (uncomplicated) or multiple (complicated) syndromes. Environmental influences are important for the etiology of functional somatic syndromes.

Are post-traumatic stress disorder symptoms and temporomandibular pain associated? Findings from a community-based twin registry

AIMS

To determine whether symptoms of post-traumatic stress disorder (PTSD) are related to the pain of temporomandibular disorders (TMD) in a community-based sample of female twin pairs, and if so, to ascertain whether the association is due to the presence of chronic widespread pain (CWP) and familial/genetic factors.

METHODS

Data were obtained from 630 monozygotic and 239 dizygotic female twin pairs participating in the University of Washington Twin Registry. PTSD symptoms were assessed with the Impact of Events Scale (IES), with scores partitioned into terciles. TMD pain was assessed with a question about persistent or recurrent pain in the face, jaw, temple; in front of the ear; or in the ear during the past 3 months. CWP was defined as pain located in 3 body regions during the past 3 months. Random-effects regression models, adjusted for demographic features, depression, CWP, and familial/genetic factors, were used to examine the relationship between the IES and TMD pain.

RESULTS

IES scores were significantly associated with TMD pain (P < .01). Twins in the highest IES tercile were almost 3 times more likely than those in the lowest tercile to report TMD pain, even after controlling for demographic factors, depression, and CWP. After adjustment for familial and genetic factors, the association of IES scores with TMD pain remained significant in dizygotic twins (Ptrend = .03) but was not significant in monozygotic twins (Ptrend = .30).

CONCLUSION

PTSD symptoms are strongly linked to TMD pain. This association could be partially explained by genetic vulnerability to both conditions but is not related to the presence of CWP. Future research is needed to understand the temporal association of PTSD and TMD pain and the genetic and physiological underpinnings of this relationship.