Associations of Psychologic Factors with Multiple Chronic Overlapping Pain Conditions

Downregulation of lysine-specific histone demethylase 1A (KDM1A/LSD1) in medial prefrontal cortex facilitates chronic stress-induced pain and emotional dysfunction in female mice

Chronic primary pain, characterized by overlapping symptoms of chronic pain, anxiety, and depression, is strongly associated with stress and is particularly prevalent among females. Recent research has convincingly linked epigenetic modifications in the medial prefrontal cortex (mPFC) to chronic pain and chronic stress. However, our understanding of the role of histone demethylation in the mPFC in chronic stress-induced pain remains limited. In this study, we investigated the function of lysine-specific histone demethylase 1A (KDM1A/LSD1) in the context of chronic overlapping pain comorbid with anxiety and depression in female mice. We employed a chronic variable stress model to induce pain hypersensitivity in the face and hindpaws, as well as anxiety-like and depression-like behaviors, in female mice. Our findings revealed that chronic stress led to a downregulation of KDM1A mRNA and protein expression in the mPFC. Notably, overexpressing KDM1A in the mPFC alleviated the pain hypersensitivity, anxiety-like behaviors, and depression-like behaviors in female mice, without affecting basal pain responses or inducing emotional distress. Conversely, conditional knockout of KDM1A in the mPFC exacerbated pain sensitivity and emotional distress specifically in females. In summary, this study highlights the crucial role of KDM1A in the mPFC in modulating chronic stress-induced overlapping pain, anxiety, and depression in females. Our findings suggest that KDM1A may serve as a potential therapeutic target for treating chronic stress-related overlap pain and associated negative emotional disorders.

[Migraine and psychosomatic comorbidity]

As a common neurological disorder (10-15% of the population), migraine is associated with numerous comorbidities, particularly other pain syndromes, mental illnesses and functional disorders. These 'psychosomatic' comorbidities increase with migraine severity. Severely affected, comorbid patients also often have a poorer response to specific migraine therapy. Interestingly, migraine and the comorbidities mentioned have a number of common aetiological or facilitating factors, e.g. genetic factors, and show a higher incidence in women and in people with previous traumatic experiences, as well as (in the case of pain syndromes) signs of central sensitization. Another common feature is the association with current or chronic stress. We propose an extended diathesis-stress model that takes into account interrelated but individually different vulnerabilities and, depending on the stress experience, can depict both the occurrence of individual disorders (e.g. an isolated migraine) and the joint occurrence of migraine with other pain syndromes and other psychosomatic comorbidities. In summary, psychosomatic comorbidities should always be kept in mind in migraine therapy and, if necessary, treated early and multimodally.

Divorce and physical health: A three-level meta-analysis

Divorce is often considered a major and stressful life transition. Given that divorcees are overrepresented in primary care and there is a association between individuals' physical health and psychological adjustment, potential post-divorce health problems are of concern. Yet, empirical evidence is lacking on the magnitude of the overall physical health risk after divorce, on possible differences across specific pathologies, and on factors that may increase or reduce this risk. The current meta-analysis addresses these issues. We identified 94 studies including u = 248 relevant effect sizes, based on N = 1,384,507 participants. Generally, compared to married individuals, divorcees showed significantly worse self-reported health (OR = 1.20, [1.08-1.33]), experienced more physical symptoms (OR = 1.34, [1.17-1.53]), and had a higher risk for diabetes (OR = 1.18 [1.05-1.33]), joint pathologies (OR = 1.24, [1.14-1.34]), cardiovascular (OR = 1.24, [1.09-1.41]) and cerebrovascular conditions (OR = 1.31, [1.14-1.51]), and sexually transmitted diseases (OR = 2.48, [1.32-4.64]). However, they had no increased risk of hypertension, hypercholesterolemia, cancer and cancer development, disabilities or limitations, or cognitive pathologies. Nor did divorcees significantly differ from married individuals when aggregating all pathologies to measure overall physical health problems (OR = 1.14, [0.85 to 1.54]). Yet, moderation analyses revealed that being female, unemployed, childless, or having a lower education constitutes a higher risk for overall physical health problems after divorce. The same applied to having a heavy alcohol consumption, lack of exercise, and being overweight. Our meta-analysis shows that divorcees are at heightened risk of certain pathologies, with sexually transmitted diseases as a particular post-divorce hazard. These findings call for more awareness among counsellors and physicians on divorcees' health conditions and the characteristics that make divorcees even more vulnerable to health problems.

A mouse model of chronic primary pain that integrates clinically relevant genetic vulnerability, stress, and minor injury

Chronic primary pain conditions (CPPCs) affect over 100 million Americans, predominantly women. They remain ineffectively treated, in large part because of a lack of valid animal models with translational relevance. Here, we characterized a CPPC mouse model that integrated clinically relevant genetic (catechol-O-methyltransferase; COMT knockdown) and environmental (stress and injury) factors. Compared with wild-type mice, Comt+/- mice undergoing repeated swim stress and molar extraction surgery intervention exhibited pronounced multisite body pain and depressive-like behavior lasting >3 months. Comt+/- mice undergoing the intervention also exhibited enhanced activity of primary afferent nociceptors innervating hindpaw and low back sites and increased plasma concentrations of norepinephrine and pro-inflammatory cytokines interleukin-6 (IL-6) and IL-17A. The pain and depressive-like behavior were of greater magnitude and longer duration (≥12 months) in females versus males. Furthermore, increases in anxiety-like behavior and IL-6 were female-specific. The effect of COMT genotype × stress interactions on pain, IL-6, and IL-17A was validated in a cohort of 549 patients with CPPCs, demonstrating clinical relevance. Last, we assessed the predictive validity of the model for analgesic screening and found that it successfully predicted the lack of efficacy of minocycline and the CB2 agonist GW842166X, which were effective in spared nerve injury and complete Freund's adjuvant models, respectively, but failed in clinical trials. Yet, pain in the CPPC model was alleviated by the beta-3 adrenergic antagonist SR59230A. Thus, the CPPC mouse model reliably recapitulates clinically and biologically relevant features of CPPCs and may be implemented to test underlying mechanisms and find new therapeutics.

Social health in young women with chronic pain

Introduction

Chronic pain may negatively affect social functioning, but no study to date has examined the specific social impact of different chronic pain conditions in young women, and whether living with multiple chronic overlapping pain conditions (COPCs) differently influences social domains.

Objectives

This study aimed to assess social functioning (social isolation, hostility, informational support satisfaction, social roles, emotional support, friendships, and family relationships) among young women with chronic pain compared with pain-free controls and to test whether the number of COPCs influenced the extent of social burden.

Methods

Participants aged 18 to 30 years with a physician-confirmed diagnoses of migraine, fibromyalgia, or temporomandibular disorder (TMD) and pain-free controls were invited to participate from across the United States. After confirming eligibility, participants completed a 1-hour REDCap online questionnaire assessing social functioning.

Results

One hundred four participants (mean age 24.54 ± 3.35 years) were included (n = 26 with TMD, n = 25 with fibromyalgia, n = 25 with migraine, and n = 28 controls). All 3 chronic pain groups combined reported worse functioning than controls on friendship (P = 0.038), social isolation (P = 0.002), and social roles (P < 0.001). There were no differences on social variables between the 3 chronic pain groups (all P's > 0.05). Compared with those with 3 COPCs, participants with 1 condition reported better family relationships (P = 0.024).

Conclusions

Experience of chronic pain-regardless of the specific pain condition-may negatively affect some areas of social functioning in young women.

Whiplash trauma did not predict jaw pain after 2 years: an explorative study

OBJECTIVES

To explore predictive factors for the development and maintenance of jaw pain over a 2-year period.

METHODS

One hundred nineteen cases (73 women) and 104 controls (59 women), mean age 34.9 years (SD 13.9), attended baseline and 2-year follow-up examinations. The whiplash cases visited the emergency department at Umeå University Hospital, Sweden, with neck pain within 72 h following a car accident, and baseline questionnaires were answered within a month after trauma. Controls were recruited via advertising. Inclusion criteria were age 18-70 years, living in Umeå municipality and Swedish speaking. The exclusion criterion was neck fracture for cases and a previous neck trauma for controls. Validated questionnaires recommended in the standardized Research Diagnostic Criteria for temporomandibular disorders were used. Jaw pain was assessed by two validated screening questions answered with "yes" or "no." A logistic regression analysis was used to predict the outcome variable jaw pain (yes/no) after 2 years.

RESULTS

Whiplash trauma did not increase the odds of development of jaw pain over a 2-year period (OR 1.97, 95% CI 0.53-7.38). However, non-specific physical symptoms (OR 8.56, 95% CI 1.08-67.67) and female gender (OR 4.89, 95% CI 1.09-22.02) did increase the odds for jaw pain after 2 years.

CONCLUSION

The development and maintenance of jaw pain after whiplash trauma are primarily not related to the trauma itself, but more associated with physical symptoms.

CLINICAL RELEVANCE

The development of jaw pain in connection with a whiplash trauma needs to be seen in a biopsychosocial perspective, and early assessment is recommended.

Predictors of response in PROMIS-global in a chronic low back pain specialty clinic: STarTBack and chronic overlapping pain conditions

BACKGROUND

Tools, such as the STarTBack Screening Tool (SBT), have been developed to identify risks of progressing to chronic disability in low back pain (LBP) patients in the primary care population. However, less is known about predictors of change in function after treatment in the specialty care population.

OBJECTIVE

We pursued a retrospective observational cohort study involving LBP patients seen in a multidisciplinary specialty clinic to assess which features can predict change in function at follow-up.

METHODS

The SBT was administered at initial visit, and a variety of patient characteristics were available in the chart including the presence of chronic overlapping pain conditions (COPCs). Patient Reported Outcomes Measurement Information System-10 (PROMIS-10) global physical health (PH) and global mental health (MH) were measured at baseline and at pragmatic time points during follow-up. Linear regression was used to estimate adjusted associations between available features and changes in PROMIS scores.

RESULTS

241 patients were followed for a mean of 17.0 ± 7.5 months. Mean baseline pain was 6.7 (SD 2.1), PROMIS-10 global MH score was 44.8 (SD 9.3), and PH score was 39.4 (SD 8.6). 29.7% were low-risk on the SBT, 41.8% were medium-risk, and 28.5% were high-risk. Mean change in MH and PH scores from baseline to the follow-up questionnaire were 0.86 (SD 8.11) and 2.39 (SD 7.52), respectively. Compared to low-risk patients, high-risk patients had a mean 4.35 points greater improvement in their MH score (p= 0.004) and a mean 3.54 points greater improvement in PH score (p= 0.006). Fewer COPCs also predicted greater improvement in MH and PH.

CONCLUSIONS

SBT and the presence of COPC, which can be assessed at initial presentation to a specialty clinic, can predict change in PROMIS following treatment. Effort is needed to identify other factors that can help predict change in function after treatment in the specialty care setting.

Perceived stress, coping strategies, symptoms severity and function status among carpal tunnel syndrome patients: a nurse-led correlational Study

BACKGROUND

Carpal tunnel syndrome (CTS) is a prevalent condition characterized by hand pain, tingling, and numbness. The severity of symptoms and functional status in CTS patients may be influenced by perceived stress and how individuals cope with it. However, scarce knowledge exists about the role of coping strategies as moderators in this relationship. Unfolding the role of perceived stress and coping strategies for CTS management will help the nurse to provide comprehensive and tailored nursing care. This will ultimately improve patient comfort, functionality, and quality of life.

PURPOSES

This study aimed to examine the role of coping strategies (adaptive and maladaptive) in the relationship between perceived stress and both symptoms severity and function status among those patients.

METHOD

We employed a multisite, correlational study design with moderation analysis. The study included 215 patients with CTS from neurosurgery outpatient clinics at three hospitals in Egypt. After obtaining their consent to participate, eligible participants completed anonymous, self-reported measures of perceived stress, the brief COPE inventory, and the Boston Carpal Tunnel Questionnaire. Demographic and biomedical data were also collected. The questionnaire took about 20 min to be completed. The data was collected over six months, starting in February 2023.

RESULTS

The results showed that perceived stress, adaptive coping, and maladaptive coping were significant predictors of symptoms severity and functional status. Adaptive coping moderated the relationships between perceived stress and both symptoms severity and function status, while maladaptive coping did not. The interaction between perceived stress and adaptive coping explained a moderate effect on symptoms severity and function status after controlling for the main effects and the covariates.

CONCLUSION

This study explored the relationship between perceived stress, coping strategies, and outcomes in patients with CTS. The results indicate that nurses play a vital role in assessing and assisting patients to adopt effective coping strategies to manage perceived stress and alleviate symptoms and functional impairment. Moreover, the findings support the need for psychological interventions that address both perceived stress and coping strategies as a way to enhance the functioning status and quality of life of patients with CTS.

Presence of endometriosis and chronic overlapping pain conditions negatively impacts the pain experience in women with chronic pelvic-abdominal pain: A cross-sectional survey

BACKGROUND

Evidence of overlap between endometriosis and chronic pain conditions is emerging; however, little is known about how the pain experience differs based on the presence or absence of endometriosis.

OBJECTIVES

In a sample of women reporting chronic pelvic-abdominal pain (CPP), the aim of this study was to characterize differences in pain symptomatology between women with and without endometriosis and to examine the influence of chronic overlapping pain conditions (COPCs) on pain among these two groups.

DESIGN

This was a cross-sectional study, based on an online survey.

METHODS

Participants (aged 18+ years) completed a survey collecting pain diagnoses and symptoms assessing pelvic pain severity, pain interference, and pain impact. Independent sample t-tests, chi-square, and multiple linear regression models were employed to analyze group differences in pain symptomatology and COPCs.

RESULTS

Of the 525 respondents with CPP, 25% (n = 133) reported having endometriosis. Women with endometriosis were younger at the onset of pelvic pain, relative to women without endometriosis (p = 0.04). There were no differences in age, race, ethnicity, or duration of pelvic pain between women with and without endometriosis. Women with endometriosis reported higher pelvic pain severity (+0.8, 95% CI = 0.4-1.1), pain interference (+5.9, 95% CI = 2.4-9.3), and pain impact (+1.9, 95% CI = 0.8-2.9). Endometriosis was associated with a higher number of COPCs (p = 0.003), with 25% (n = 33) of women reporting ⩾3 overlapping pain conditions compared with 12% (n = 45) of those without endometriosis. Women with endometriosis had a higher frequency of fibromyalgia (p < 0.001), chronic fatigue syndrome (p < 0.001), and temporomandibular disorder (p = 0.001). The number of COPCs was associated with higher pain severity, interference, and impact, independently of endometriosis.

CONCLUSION

Women with endometriosis experienced higher levels of pain-related burden and COPCs compared with those without endometriosis. Pain intensity, interference, and impact increased with a higher number of pain conditions regardless of endometriosis presence.

The Chronic Overlapping Pain Condition Screener

Ten Chronic Overlapping Pain Conditions (COPCs) are currently recognized by the National Institutes of Health Pain Consortium (eg, irritable bowel syndrome, chronic migraine headache, and chronic low back pain). These conditions affect millions of Americans; however, assessing these conditions, their co-occurrence, and their relationship to treatment has proven challenging due to time constraints and a lack of standardized measures. We present a Chronic Overlapping Pain Condition-Screener (COPC-S) that is logic-driven, efficient, and freely available in electronic format to nonprofit entities. Thirty experts were convened to identify and modify self-report criteria for each COPC as well as criteria that trigger the administration of the diagnostic criteria from a body map and a brief series of questions. Their recommendations were then programmed into the Research Electronic Data Capture platform and refined for comprehensibility and ease of use by patient focus groups. The electronic screener and physician-administered criteria were both administered to patients with known COPCs in a counter-balanced fashion to determine the level of agreement between methods. The expert panel identified screening items/body map regions and diagnostic criteria for all 10 COPCs. Patients found the content comprehensible and the platform easy to use. Cohen's Kappa statistics suggested good agreement between the electronic COPC-S and criteria administered by a physician (κ = .813). The COPC-S is an efficient tool for screening multiple COPCs and has applicability to research studies, clinical trials, and clinical practice. PERSPECTIVE: Assessing COPCs remains a challenge for researchers and clinicians. The COPC-S is an efficient and logic-driven electronic tool that allows for the rapid screening assessment of 10 COPCs. The instrument may have utility in research and clinical settings.

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.

Pharmacological Management of Orofacial Pain

Orofacial pain is a category of complex disorders, including musculoskeletal, neuropathic and neurovascular disorders, that greatly affect the quality of life of the patient. These disorders are within the fields of dentistry and medicine and management can be challenging, requiring a referral to an orofacial pain specialist, essential for adequate evaluation, diagnosis, and care. Management is specific to the diagnosis and a treatment plan is developed with diverse pharmacological and non-pharmacological modalities. The pharmacological management of orofacial pain encompasses a vast array of medication classes and approaches. This includes anti-inflammatory drugs, muscle relaxants, anticonvulsants, antidepressants, and anesthetics. In addition, as adjunct therapy, different injections can be integrated into the management plan depending on the diagnosis and needs. These include trigger point injections, temporomandibular joint (TMJ) injections, and neurotoxin injections with botulinum toxin and nerve blocks. Multidisciplinary management is key for optimal care. New and safer therapeutic targets exclusively for the management of orofacial pain disorders are needed to offer better care for this patient population.

Cannabinoid Therapy: Attitudes and Experiences of People With Chronic Pain

OBJECTIVE

Clinical trials of cannabinoids for chronic pain have mixed and often inconclusive results. In contrast, many prospective observational studies show the analgesic effects of cannabinoids. This survey study aimed to examine the experiences/attitudes of individuals with chronic pain who are currently taking, have previously taken, or never taken cannabinoids for chronic pain to inform future research.

METHODS

This study is based on a cross-sectional, web-based survey of individuals with self-reported chronic pain. Participants were invited to participate through an email that was distributed to the listservs of patient advocacy groups and foundations that engage individuals with chronic pain.

RESULTS

Of the 969 respondents, 444 (46%) respondents reported currently taking, 213 (22%) previously taken, and 312 (32%) never taken cannabinoids for pain. Participants reported using cannabinoids to treat a wide variety of chronic pain conditions. Those currently taking cannabinoids (vs previously) more frequently reported: (1) large improvements from cannabinoids in all pain types, including particularly difficult-to-treat chronic overlapping pain conditions (eg, pelvic pain), (2) improvements in comorbid symptoms (eg, sleep), and (3) lower interference from side effects. Those currently taking cannabinoids reported more frequent and satisfactory communication with clinicians regarding cannabinoid use. Those never taken cannabinoids reported a lack of suggestion/approval of a clinician (40%), illegality (25%), and lack of FDA regulation (19%) as reasons for never trying cannabinoids.

CONCLUSION

These findings underscore the importance of conducting high-quality clinical trials that include diverse pain populations and clinically relevant outcomes that if successful, could support FDA approval of cannabinoid products. Clinicians could then prescribe and monitor these treatments similarly to other chronic pain medications.

A rose by another name? Characteristics that distinguish headache secondary to temporomandibular disorder from headache that is comorbid with temporomandibular disorder

ABSTRACT

Co-occurring pain conditions that affect overlapping body regions are complicated by the distinction between primary vs secondary pain conditions. We investigate the occurrence of headache and painful temporomandibular disorder (TMD) in a community-based, cross-sectional study of US adults in the Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA-II) study. A specific goal was to determine whether headache attributed to TMD is separable from primary headache. Using DC/TMD and International Classification of Headache Disorders-third edition criteria, 3 groups of individuals were created: (a) headache without TMD; (b) headache comorbid with TMD; and (c) headache attributed to TMD. Regression models compared study groups according to demographic and comorbid characteristics, and post hoc contrasts tested for differences. Descriptive statistics and Cohen d effect size were computed, by group, for each predictor variable. Differences in continuous predictors were analyzed using one-way analysis of variance. Nearly all demographic and comorbid variables distinguished the combined headache and TMD groups from the group with headache alone. Relative to the reference group with primary headache alone, markers related to headache, TMD, somatic pain processing, psychosocial, and health conditions were substantially greater in both headache comorbid with TMD and headache attributed to TMD, attesting to their qualitative similarities. However, effect sizes relative to the reference group were large for headache comorbid with TMD and larger again for headache attributed to TMD, attesting to their separability in quantitative terms. In summary, the presence of overlapping painful TMD and headache adds substantially to the biopsychosocial burden of headache and points to the importance of comprehensive assessment and differential management.

Pathogenesis and Differential Diagnosis of Temporomandibular Joint Disorders

Temporomandibular disorders (TMDs) are an umbrella term including disorders of the temporomandibular joint and muscles of the masticatory system. They are the most common nonodontogenic cause of pain in the orofacial region. A clear understanding of various conditions, underlying mechanisms, clinical presentation, and examination skills is required to effectively diagnose and manage these patients.

Racism exposure and trauma accumulation perpetuate pain inequities-advocating for change (RESTORATIVE): A conceptual model

Experiences of racism occur across a continuum from denial of services to more subtle forms of discrimination and exact a significant toll. These multilevel systems of oppression accumulate as chronic stressors that cause psychological injury conceptualized as racism-based traumatic stress (RBTS). RBTS has overlapping symptoms with posttraumatic stress disorder (PTSD) with the added burden that threats are constantly present. Chronic pain is a public health crisis that is exacerbated by the intersection of racism and health inequities. However, the relationship between RBTS and pain has not yet been explored. To highlight how these phenomena are interlinked, we present Racism ExpoSure and Trauma AccumulatiOn PeRpetuate PAin InequiTIes-AdVocating for ChangE (RESTORATIVE); a novel conceptual model that integrates the models of racism and pain and demonstrates how the shared contribution of trauma symptoms (e.g., RBTS and PTSD) maintains and perpetuates chronic pain for racialized groups in the United States. Visualizing racism and pain as "two halves of the same coin," in which the accumulative effects of numerous events may moderate the severity of RBTS and pain, we emphasize the importance of within-group distinctiveness and intersectionality (overlapping identities). We call on psychologists to lead efforts in applying the RESTORATIVE model, acting as facilitators and advocates for the patient's lived experience with RBTS in clinical pain care teams. To assist with this goal, we offer suggestions for provider and researcher antiracism education, assessment of RBTS in pain populations, and discuss how cultural humility is a central component in implementing the RESTORATIVE model. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

How negative and positive constructs and comorbid conditions contribute to disability in chronic orofacial pain

BACKGROUND

Temporomandibular disorders (TMD) symptoms develop into chronic pain for some patients, but the reasons for this are unclear. Psychosocial factors and chronic overlapping pain conditions are believed to contribute to the development of pain-related disability. We examined the role of jaw function, negative and positive psychological factors and chronic overlapping pain conditions (COPCs) on pain-related disability whilst controlling for demographic variables.

METHODS

We collected demographics, medical and psychosocial history and the Graded Chronic Pain Scale, a measure of pain intensity and pain interference from 400 participants with chronic TMD. Structural equation modelling was used to assess a model of COPCs and the latent variables of psychological unease (pain catastrophizing, somatic symptoms and negative affect), positive valence factors (optimism and positive affect), jaw function (chewing, opening and expression limitation) and pain-related disability (pain intensity and pain interference) whilst controlling for demographic variables.

RESULTS

We achieved good fit of a parsimonious model (root-mean-square error of approximation = 0.063 [90% CI] [0.051-0.075]), comparative fit index = 0.942, standard root-mean-square residual = 0.067. Jaw function was the strongest latent variable predictor, followed by psychological unease and COPCs suggesting resources focused on improving joint function, psychosocial support and management of COPCs will improve pain-related disability in TMDs.

CONCLUSIONS

These findings not only increase the body of knowledge related to TMD clinical phenotypes but also, have a translational impact in further supporting the potential value of targeting physical therapy such as jaw exercise along with psychological interventions as multidisciplinary nonpharmacological therapeutic solutions.

Posttraumatic Stress Disorder and the Role of Psychosocial Comorbidities in Chronic Orofacial Pain

This article presents the case of a patient with persistent right-sided jaw pain with a history of multiple temporomandibular joint surgeries in the setting of persistent widespread body pain, the causes of which were fibromyalgia and osteoarthritis with multiple joint replacements, as well as psychological diagnoses of PTSD and depression. Despite extensive treatment from her orofacial pain team in combination with neurology and neurosurgery, her severe pain persisted, likely due to the consequences of untreated PTSD and depression, which led to avoidance of activities that would exacerbate her pain and thus to further disability and emotional deterioration.

CMD und Kieferorthopädie

Die Craniomandibuläre Dysfunktion (CMD) ist mit einer Prävalenz von über 30% die häufigste chronische Schmerzerkrankung im Kiefer- Gesichtsbereich. Die Therapie erfordert einen interdisziplinären, individuell angepassten Behandlungsansatz. Diese Fallvorstellung soll einen Einblick über das Behandlungskonzept eines posterior-lateralen Zwangsbisses mit Oberkiefer- Okklusionsschiene und OK/UK Alignern (Invisalign) geben.

Migraine in the context of chronic primary pain, chronic overlapping pain disorders, and functional somatic disorders: A narrative review

OBJECTIVE

To contextualize migraine as the most common primary headache disorder in relation to other chronic primary pain and non-pain functional somatic and mental conditions.

BACKGROUND

Migraine is increasingly understood as a sensory processing disorder within a broader spectrum of symptom disorders. This has implications for diagnosis and treatment.

METHOD

Narrative review based on a search of the literature of the last 15 years on the overlap of migraine with other symptom disorders.

RESULTS

Migraine as the prototypical primary headache disorder not only comprises many non-headache symptoms in itself, it also shows high comorbidity with other chronic pain and non-pain conditions (e.g., fibromyalgia syndrome, irritable bowel syndrome, functional non-epileptic seizures, depression, anxiety, and posttraumatic stress disorder). Such "symptom disorders" share several etiological factors (e.g., female preponderance, psychological vulnerability) and psychophysiological mechanisms (e.g., altered sensory processing, pain expectancy). These facts are acknowledged by several recent integrative conceptualizations such as chronic primary pain, chronic overlapping pain conditions, or functional somatic disorders. Accordingly, migraine management increasingly addresses the total symptom burden and individual contributors to symptom experience, and thus incorporates centrally acting pharmacological and non-pharmacological, that is, psychological and behavioral, treatment approaches.

CONCLUSIONS

Migraine and also other primary headache disorders should be seen as particular phenotypes within a broader spectrum of symptom perception and processing disorders that require integrative diagnostics and treatment. A harmonization of classifications and better interdisciplinary collaboration are desirable.

Ratio of Omega-6/Omega-3 Polyunsaturated Fatty Acids Associated With Somatic and Depressive Symptoms in People With Painful Temporomandibular Disorder and Irritable Bowel Syndrome

Somatic symptom disturbance is among the strongest predictors of painful temporomandibular disorder (TMD). Related psychological constructs, such as anxiety and depression, respond therapeutically to omega-3 polyunsaturated fatty acids (PUFAs) in clinical trials. This cross-sectional study investigated associations between the omega-6/omega-3 PUFA ratio and somatic symptom disturbance and depressive symptoms in a community-based sample of 501 adults and determined whether these associations differed between adults with and without TMD or irritable bowel syndrome (IBS). Liquid chromatography tandem mass spectrometry quantified PUFAs in circulating erythrocytes. Somatic symptoms and depression were quantified using Symptom Checklist-90-Revised subscales. Presence or absence of TMD and IBS, respectively, were determined by clinical examination and Rome III screening questions. The standardized beta coefficient for the omega-6/omega-3 long-chain PUFA ratio was 0.26 (95% confidence limits (CL): 0.08, 0.43) in a multivariable linear regression model in which somatic symptom disturbance was the dependent variable. When modelling depressive symptoms as the dependent variable, the standardized beta coefficient was 0.17 (95% CL:0.01, 0.34). Both associations were stronger among TMD cases and IBS cases than among non-cases. Future randomized control trials that lower the omega-6/omega-3 PUFA ratio could consider somatic or depressive symptoms as a therapeutic target for TMD or IBS pain. PERSPECTIVE: In people with TMD or IBS, a high n-6/n-3 PUFA ratio was positively associated with somatic symptom disturbance and depressive symptoms. Both measures of psychological distress were elevated in people with painful TMD and IBS. Future randomized clinical trials will determine whether lowering the n-6/n-3 ratio is therapeutic for pain.

Neural Basis of Etiopathogenesis and Treatment of Cervicogenic Orofacial Pain

(1) Background and Objectives: The aim of this narrative review was to analyze the neuroanatomical and neurophysiological basis of cervicogenic pain in cervico-cranial pain syndromes, focusing particularly on cervico-orofacial syndromes as a background for the proper diagnosis and non-surgical treatment. Relevant literature on the topic from past 120 years has been surveyed. (2) Material and Methods: We surveyed all original papers, reviews, or short communications published in the English, Spanish, Czech or Slovak languages from 1900 to 2020 in major journals. (3) Results: The cervicogenic headache originates from the spinal trigeminal nucleus where axons from the C₁–C₃ cervical spinal nerves and three branches of the trigeminal nerve converge (trigeminocervical convergence) at the interneurons that mediate cranio-cervical nociceptive interactions. The role of the temporomandibular joint in the broad clinical picture is also important. Despite abundant available experimental and clinical data, cervicogenic orofacial pain may be challenging to diagnose and treat. Crucial non-surgical therapeutic approach is the orthopedic manual therapy focused on correction of body posture, proper alignment of cervical vertebra and restoration of normal function of temporomandibular joint and occlusion. In addition, two novel concepts for the functional synthesis of cervico-cranial interactions are the tricentric concept of mouth sensorimotor control and the concept of a cervicogenic origin of bruxism. (4) Conclusions: Understanding the basis of neuroanatomical and neurophysiological neuromuscular relations enables an effective therapeutic approach based principally on orthopedic manual and dental occlusal treatment.

Circulating polyunsaturated fatty acids, pressure pain thresholds, and nociplastic pain conditions

OBJECTIVE

Polyunsaturated fatty acids (PUFAs) play a role in pain regulation. This study sought to determine whether free PUFAs found in red blood cells also play a role in nociceptive processing. We examined associations between circulating PUFAs and nociceptive thresholds to noxious mechanical stimuli. We also determined whether nociceptive thresholds were associated with nociplastic pain conditions.

METHODS

This cross-sectional study used stored red bloods cells and data from 605 adult participants in the OPPERA-2 study of chronic overlapping pain conditions. In OPPERA-2 adults completed quantitative sensory testing in which pressure algometry measured deep muscular tissue sensitivity at six anatomical sites. Standardized protocols classified adults for presence or absence of five nociplastic pain conditions: temporomandibular disorder, headache, low back pain, irritable bowel syndrome and fibromyalgia. Liquid chromatography tandem mass spectroscopy quantified erythrocyte PUFAs. We conducted three sets of analyses. First, a multivariable linear regression model assessed the association between n-6/n-3 PUFA ratio and the number of overlapping nociplastic pain conditions. Second, a series of 36 multivariable linear regression models assessed covariate-adjusted associations between PUFAs and nociceptive thresholds at each of six anatomical sites. Third, a series of 30 multivariable linear regression models assessed covariate-adjusted associations between nociceptive thresholds at six anatomical sites and each of five pain conditions.

RESULTS

In multiple linear regression, each unit increase in n-6/n-3 PUFA ratio was associated with more pain conditions (β = 0.30, 95% confidence limits: 0.07, 0.53, p = 0.012). Omega-6 linoleic acid and arachidonic acid were negatively associated with lower nociceptive thresholds at three and at five, respectively, anatomical sites. In contrast, omega-3 alpha-linolenic acid, eicosapentaenoic acid, docosahexaenoic acid and the n-6/n-3 PUFA ratio were not associated with nociceptive thresholds at any site. Pain cases had significantly lower nociceptive thresholds than non-case controls at all anatomical sites.

CONCLUSION

A higher n-6/n-3 PUFA ratio was associated with more pain conditions. Omega-6 PUFAs may promote a generalized upregulation of nociceptive processing.

Psychosocial Variables and Healthcare Resources in Patients with Fibromyalgia, Migraine and Comorbid Fibromyalgia and Migraine: A Cross-Sectional Study

Fibromyalgia and migraine frequently coexist. We aimed to compare the burden caused by fibromyalgia (FM), migraine (M) and comorbid fibromyalgia and migraine (FM + M) by assessing psychosocial variables and the use of healthcare resources. A survey was posted to the websites of different patients’ associations. It included sociodemographic data, the Patient Health Questionnaire-9, the Insomnia Severity Index, the EuroQOL-5D-5L and a questionnaire evaluating the use of healthcare resources during the past six months. In total, 139 FM patients, 169 M patients and 148 FM + M patients participated in the survey. Mean depression and insomnia scores were clinically relevant in every group and significantly higher in FM + M (16.3 ± 5.4 for depression, 18.5 ± 5.6 for insomnia) than in FM (14.3 ± 5.7 for depression, 16.8 ± 5.5 for insomnia) or M (11.7 ± 5.4 for depression, 13.1 ± 5.9 for depression), where p < 0.001 in both cases. Suicidal ideation was frequent in every group, but significantly more frequent in FM + M (63% vs. 45% in FM and 35% in M; p < 0.001). EQ-5D-5L (0.656 ± 0.1 in FM + M, 0.674 ± 0.1 in FM, 0.827 ± 0.1 in M, p < 0.001) and EQ-5D-5L VAS scores (38.2 ± 21.9 in FM + M, 45.6 ± 21.8 in FM, 63.5 ± 23.7 in M, p < 0.00) were lower than the reported mean population values and the lowest in FM + M. FM and FM + M used more healthcare resources than M. It is concluded that the psychosocial burden was high in the three samples. FM and FM + M had a more relevant impact on patients’ wellbeing and required more medical attention than M. The burden caused by FM + M was higher than in both individual diseases.

The association between myofascial orofacial pain with and without referral and widespread pain

OBJECTIVES

Pain referral on palpation has been suggested to be a clinical sign of central sensitization potentially associated with widespread pain conditions. Our aim was to evaluate if myofascial pain with referral is a better predictor for widespread pain when compared to no pain or local myofascial pain.

MATERIALS AND METHODS

Individuals at the Public Dental services in Västerbotten, Sweden, were randomly invited based on their answers to three screening questions for temporomandibular disorders (TMD). In total, 300 individuals (202 women, 20-69 yrs) were recruited, and examined according to the Diagnostic Criteria for TMD (DC/TMD) after completion of a body pain drawing. Widespread pain was considered present when seven or more pain sites were reported on the widespread pain index. A binary logistic regression model, adjusted for the effect of age and gender were used to evaluate the association between myofascial orofacial pain and widespread pain.

RESULTS

Widespread pain was reported by 31.3% of the study sample. There was a 57.3% overlap with myofascial pain. Widespread pain was associated to myofascial orofacial pain with and myofascial orofacial pain (OR 4.83 95% CI 2.62-9.05 and OR 11.62 95% CI 5.18-27.88, respectively).

CONCLUSION

These findings reinforce the existing knowledge on the overlap between painful TMD and other chronic pain conditions.

Catastrophizing as a prognostic factor for pain and physical function in the multidisciplinary rehabilitation of fibromyalgia and low back pain

BACKGROUND

Quantitative data on longitudinal associations between catastrophizing and pain or physical function are patchy. The study aimed to quantify the prognostic value of catastrophizing for pain and function in fibromyalgia and low back pain before and after rehabilitation.

METHODS

The associations of state and change on the Multidimensional Pain Inventory (MPI) Pain severity scale, the Short Form 36 (SF-36) Physical functioning scale, and the Six-Minute Walking Distance (6MWD) with the Coping Strategies Questionnaire (CSQ) Catastrophizing scale were quantified by multiple regression modeling to adjust for confounders.

RESULTS

Sex- and age matched cohorts (n=71 each) were compared. Pain and catastrophizing were worse in fibromyalgia than in low back pain, whereas the function levels were comparable. Baseline catastrophizing predicted pain change by adjusted correlations of 0.552 (fibromyalgia) and 0.450 (low back pain), self-rated function by 0.403 and 0.308, and the 6MWD by 0.270 and -0.072. The change in catastrophizing was associated to the change in pain by 0.440 (fibromyalgia) and 0.614 (low back pain), self-rated function by 0.122 and 0.465, and the 6MWD by 0186 and 0.162.

CONCLUSIONS

Catastrophizing (pain-related worrying) was a potential prognostic factor, especially for pain and somewhat less for self-rated physical function but it was only weakly predictive for the walking distance in both conditions, independently of potential confounders, such as sex, age, baseline severity and others. Reduction of maladaptive coping should be integrated into the management of chronic pain.

Whole Body Pain Distribution and Risk Factors for Widespread Pain Among Patients Presenting with Abdominal Pain: A Retrospective Cohort Study

Introduction

Abdominal pain frequently co-occurs with pain in other body sites. Chronic overlapping pain conditions (COPCs) represent a group of widespread pain diagnoses. Our study characterized how patterns of somatic pain distribution are associated with COPCs and aimed to characterize predictors of widespread pain among patients with chronic abdominal pain.

Methods

This retrospective cohort study included adults presenting to a tertiary pain clinic, reporting abdominal pain at their initial visit, and with a follow-up visit at 12 months. Body maps divided patients into localized, intermediate, and widespread pain distribution patterns. Diagnostic and psychosocial measures were assessed across groups at the initial and follow-up visits. We analyzed the association of baseline diagnoses and demographics and time-varying changes in psychosocial measures from initial to follow-up visit with changes in pain distribution over time with alternating logistic regression (ALR).

Results

Among 258 patients, most were female (91.5%) and reported widespread pain (61.5%). Those with widespread pain at baseline reported elevated anger and 60.0% of patients remained in the same pain category at follow-up. Multivariable ALR demonstrated higher pain interference (AOR 1.06, 95% CI 1.02–1.10, P = 0.002), higher anxiety (AOR 1.05, 95% CI 1.01–1.09, P = 0.01), more than one COPC at initial visit (AOR 2.85, 95% CI 1.59–5.11, P = 0.0005), and initial visit widespread pain categorization (AOR 4.18, 95% CI 2.20–8.00, P < 0.0001) were associated with an increased risk of widespread pain at the follow-up visit.

Conclusion

Most patients with abdominal pain report additional pain locations at multiple other body sites, and non-localized pain persists 12 months after pain treatment. Screening for widespread pain and COPC at the initial visit may identify patients at higher risk for persistent or new-onset widespread pain, and interventions to reduce pain interference and anxiety may promote reversal of widespread pain.

The prevalence of comorbid chronic pain conditions among patients with temporomandibular disorders: A systematic review

BACKGROUND

This systematic review was designed to evaluate the presence of comorbid conditions among patients with temporomandibular disorders (TMDs).

TYPES OF STUDIES REVIEWED

The authors reviewed studies that reported the prevalence or incidence of chronic pain conditions or psychiatric disorders (anxiety, mood, personality disorders) among patients with any type of TMD. The authors calculated sample size-weighted prevalence estimates when data were reported in 2 or more studies for the same comorbid condition.

RESULTS

A total of 9 prevalence studies and no incidence studies were eligible for review; 8 of the studies examined chronic pain comorbidities. Weighted estimates showed high prevalence of pain comorbidities across studies, including current chronic back pain (66%), myofascial syndrome (50%), chronic stomach pain (50%), chronic migraine headache (40%), irritable bowel syndrome (19%), and fibromyalgia (14%). A single study examined psychiatric disorders and found that current depression was the most prevalent disorder identified (17.5%).

CONCLUSIONS AND PRACTICAL IMPLICATIONS

There is a high prevalence of comorbid chronic pain conditions among patients with TMDs, with more than 50% of patients reporting chronic back pain, myofascial syndrome, and chronic stomach pain. Psychiatric disorders among patients with different types of TMDs were studied less commonly in this pain population. Knowledge of the distribution of these and other comorbid disease conditions among patients with different types of TMDs can help dentists and other health care providers to identify personalized treatment strategies, including the coordination of care across medical specialties.

Oxygen-Ozone Therapy for Reducing Pro-Inflammatory Cytokines Serum Levels in Musculoskeletal and Temporomandibular Disorders: A Comprehensive Review

To date, the application of oxygen-ozone (O₂O₃) therapy has significantly increased in the common clinical practice in several pathological conditions. However, beyond the favorable clinical effects, the biochemical effects of O₂O₃ are still far from being understood. This comprehensive review aimed at investigating the state of the art about the effects of O₂O₃ therapy on pro-inflammatory cytokines serum levels as a modulator of oxidative stress in patients with musculoskeletal and temporomandibular disorders (TMD). The efficacy of O₂O₃ therapy could be related to the moderate oxidative stress modulation produced by the interaction of ozone with biological components. More in detail, O₂O₃ therapy is widely used as an adjuvant therapeutic option in several pathological conditions characterized by chronic inflammatory processes and immune overactivation. In this context, most musculoskeletal and temporomandibular disorders (TMD) share these two pathophysiological processes. Despite the paucity of in vivo studies, this comprehensive review suggests that O₂O₃ therapy might reduce serum levels of interleukin 6 in patients with TMD, low back pain, knee osteoarthritis and rheumatic diseases with a concrete and measurable interaction with the inflammatory pathway. However, to date, further studies are needed to clarify the effects of this promising therapy on inflammatory mediators and their clinical implications.

Graded Chronic Pain Scale: Validation of 1-Month Reference Frame

OBJECTIVES

The 1-month Graded Chronic Pain Scale (GCPS) commonly used in clinical studies has never been validated. This study compares the GCPS 1-month with the 6 months version for reliability and validity.

METHODS

The Validation Project included 521 participants with at least one temporomandibular disorder for cross-sectional data and 74 participants for test-retest data. Internal reliability, stability, and construct validity were used for testing the 1-month version. Comparisons were made between the 2 versions for characteristic pain intensity (CPI), interference, and chronic pain grade (CPG).

RESULTS

For GCPS 1-month, internal consistency for pain intensity and interference was high (Cronbach α=0.87 and 0.94, respectively), and temporal stability was high for CPI (intraclass correlation coefficient [ICC]=0.91), interference (ICC=0.85), and CPG (weighted κ=0.88). ICC or κ between the 2 versions was 0.78 (CPI), 0.66 (interference), and 0.69 (CPG); high-impact pain, in contrast, was 0.50. Construct validity exhibited higher correlations with predictor variables for 1-month version attributes of CPI, interference, and CPG. Modified Bland-Altman plots indicated that both versions measure CPI well.

DISCUSSION

Overall, reliability of the 1-month GCPS is equal to or better than the 6-months version for pain intensity, disability days, pain interference, CPG, and high-impact pain. However, consistency between versions is lower for measures of disability days and interference, and for the derived measures of CPG and high-impact pain; highly skewed distributions and increasing disagreement in reported status over the time periods affect the measures of function. Therefore, we recommend that GCPS-1 month only be used to calculate pain intensity and pain interference.

Sexual dimorphism in functional pain syndromes

Sexual dimorphism in functional pain suggests the need of developing sex-specific therapies.

Outcomes of referrals from endodontic to orofacial pain specialists: A retrospective cohort study

OBJECTIVES

Diagnosis and treatment of non-odontogenic pain is challenging for endodontists. The purpose of the study was to investigate the outcomes of referrals to orofacial pain specialists made for patients with suspected non-odontogenic pain, after evaluation and/or treatment by an endodontist.

MATERIALS AND METHODS

A retrospective review of dental records was conducted for 60 patients referred from a postgraduate endodontic clinic to an orofacial pain clinic. Patient demographics, pain history, endodontic, and orofacial pain diagnoses were collected. Number of visits, length of treatment, and treatments prescribed were recorded. For analysis of outcomes, data pertinent to resolution/persistence of symptoms and patient compliance were analyzed.

RESULTS

Thirty-five patients were included in the study. The most frequent pulpal and periapical diagnoses were previously treated (62%) and symptomatic apical periodontitis (72%), respectively. The most common orofacial pain diagnosis was temporomandibular disorder. The average time spent to diagnose and treat the pain was 17 months. Pain reduction varied and was documented for 51% of patients. Indications of non-compliance with orofacial pain appointments and treatments were documented for 66% of patients.

CONCLUSIONS

Non-odontogenic pain diagnosis and treatment are challenging. Patients may have an increased predilection for developing persistent pain after endodontic treatment and/or have an undiagnosed, chronic orofacial pain condition as a true source of their chief complaint. It may be helpful for endodontists to set expectations of typical treatment times/plans when referring patients for evaluation and treatment of non-odontogenic pain.

Differential Activation of Colonic Afferents and Dorsal Horn Neurons Underlie Stress-Induced and Comorbid Visceral Hypersensitivity in Female Rats

Chronic Overlapping Pain Conditions, including irritable bowel syndrome (IBS) and temporomandibular disorder (TMD), represent a group of idiopathic pain conditions that likely have peripheral and central mechanisms contributing to their pathology, but are poorly understood. These conditions are exacerbated by stress and have a female predominance. The presence of one condition predicts the presence or development of additional conditions, making this a significant pain management problem. The current study was designed to determine if the duration and magnitude of peripheral sensitization and spinal central sensitization differs between restraint stress-induced visceral hypersensitivity (SIH) and chronic comorbid pain hypersensitivity (CPH; stress during pre-existing orofacial pain). SIH in female rats, as determined by the visceromotor response, persisted at least four but resolved by seven weeks. In contrast, CPH persisted at least seven weeks. Surprisingly, colonic afferents in both SIH and CPH rats were sensitized at seven weeks. CPH rats also had referred pain through seven weeks, but locally anesthetizing the colon only attenuated the referred pain through four weeks, suggesting a transition to colonic afferent independent central sensitization. Different phenotypes of dorsal horn neurons were sensitized in the CPH rats seven weeks post stress compared to four weeks or SIH rats. The current study suggests differential processing of colonic afferent input to the lumbosacral spinal cord contributes to visceral hypersensitivity during comorbid chronic pain conditions. PERSPECTIVE: Chronic Overlapping Pain Conditions represent a unique challenge in pain management. The diverse nature of peripheral organs hinders a clear understanding of underlying mechanisms accounting for the comorbidity. This study highlights a mismatch between the condition-dependent behavior and peripheral and spinal mechanisms that contribute to visceral pain hypersensitivity.

Even mild catastrophic thinking is related to pain intensity in individuals with painful temporomandibular disorders

AIMS

Temporomandibular disorders (TMD) are often associated with psychological comorbidities. One such comorbidity is pain catastrophising, that is, exaggeration of negative consequences of a painful event. The aim was to investigate catastrophising in individuals with painful TMD compared to controls and the association between catastrophising and pain intensity, number of pain sites and functional limitations.

METHODS

A community-based sample of 110 individuals (83 women; 20-69 yrs) with painful TMDs (myalgia/arthralgia as per Diagnostic Criteria for TMD) and 190 age- and gender-matched controls (119 women; 20-69 yrs) from the Public Dental services in Västerbotten, Sweden, participated. Associations between catastrophising and functional jaw limitations, respectively, and painful TMD were evaluated with ordinal regression adjusted for the effect of gender and age. Associations (Spearman's correlation) of the Pain catastrophising Scale (PCS) with Jaw Functional Limitation Scale (JFLS-20), pain site number (whole-body pain map), and characteristic pain intensity (CPI) and intergroup comparisons (Mann-Whitney U test) of these variables were also calculated.

RESULTS

Levels of catastrophising were associated with TMD pain (OR 1.6, 95%CI 1.1-2.6). Among individuals with painful TMD, catastrophising was correlated to pain intensity (r=0.458, p<0.01) and functional limitations (r=0.294-0.321, p≤0.002), but not to number of pain sites.

CONCLUSION

Compared to controls, community-based individuals with painful TMD demonstrated higher levels of pain catastrophising, and this catastrophising was associated with increased pain intensity and jaw dysfunction. The relatively low scores of pain catastrophising suggest that even mild catastrophic thinking is associated with pain perception and jaw function, and should be considered in patient management.

From One Pain to Many: The Emergence of Overlapping Pains in Children and Adolescents

OBJECTIVES

The objective of this study was to compare children and adolescents with overlapping chronic pains (OCP) to those with single chronic pains (SCP) among youth presenting in specialized clinical settings, in an effort to identify potential risk factors for developing overlapping pains.

METHODS

A total of 1235 youth ages 8 to 18 seen in a tertiary care multidisciplinary pain clinic or a multidisciplinary headache clinic completed self-report measures of pain, disability, psychological functioning and clinical history and characteristics at the time of initial clinic visit. Information was captured in a chronic pain data repository and accessed for the current study.

RESULTS

Subsequent pain symptoms developed on average 11.9 months (SD=24.5 mo) after onset of the first pain symptom. Compared with patients with SCP, patients with OCP report more medical comorbidity, more developmental issues, and poorer current sleep and school functioning. They also scored significantly higher than patients with SCP on self-reported functional disability, pain catastrophizing, fear of pain, depression, anxiety, and psychological stress and lower quality of life (all Ps<0.001). In multivariate analysis, variables most strongly associated with presenting with OCP were age (odds ratio [OR]: 1.1, P<0.001), having a clinically significant high functional disability (OR: 1.4, P=0.3), and low quality of life (OR: 2.5, P<0.001).

DISCUSSION

Given their tendency toward more psychological and medical comorbidities, patients with OCP may require more intense and diverse treatment approaches. Some early life experiences may be a risk factor for development of OCP. Longitudinal studies are needed to fully evaluate the heightened risk for OCP associated with some of these factors.

Decline of anterior cingulate functional network efficiency in first-episode, medication-naïve somatic symptom disorder and its relationship with catastrophizing

The high prevalence of somatic symptom disorder (SSD) led to cumulative burdens to the medical system. However, the pathogenesis of this disease still remains unclear. Graph theoretical analysis discovered altered network topology across various psychiatric disorders, yet alteration in the topological structure of brain functional network in SSD patients is still unexplored. Catastrophizing is a common cognitive distortion in SSD. We hypothesize that the network topological metrics of SSD should be altered, and should correlate with catastrophizing scales. 32 medication-naïve, first-episode SSD patients and 30 age, gender matched HCs were recruited. The 17-item Hamilton Depression Rating Scale (HAMD-17), Hamilton Anxiety Rating Scale (HAMA) and Cognitive Emotion Regulation Questionnaire (CERQ) were accessed. Functional MRI were scanned and brain functional networks were constructed based on 166 anatomically cerebrum regions from the automated anatomical labeling 3 (AAL3) template. Network topological metrics were calculated and compared between the two groups. Correlation between these metrics and clinical scales were also calculated. Network global efficiency of SSD was significantly lower than that of HC. Nodal global efficiency of the left subgenual anterior cingulate cortex (sgACC) of SSD was significantly lower than that of HC. FCs between the left sgACC and other 21 seed nodes were significantly declined in SSD in comparison with HC. In SSD group, HAMD total score was significantly negatively correlated with the connection between the left medial superior frontal gyrus and the left sgACC. CERQ catastrophizing score was significantly negatively correlated with nodal global efficiency of left sgACC and with the FCs between the left sgACC and other 13 seed nodes. Catastrophizing could reflect the specific sgACC-centered dysfunction of brain network global efficiency of SSD. The left sgACC may be a future treatment target of dealing with catastrophizing, which is a core cognitive distortion of SSD.

Comorbid Conditions in Temporomandibular Disorders Myalgia and Myofascial Pain Compared to Fibromyalgia

The impact of comorbidities in fibromyalgia (FM) and temporomandibular disorders (TMD) have been well documented, but whether TMD sub-diagnoses myalgia (MYA) and myofascial pain with referral (MFP) differ regarding comorbidity is unclear. We aimed to elucidate this by studying the presence and associations of comorbidities in FM, MFP and MYA. An extended version of the Diagnostic Criteria for TMD axis II questionnaire was used to examine demographics, pain and comorbidities in 81 patients with FM, 80 with MYA, and 81 with MFP. Patients with MFP and FM reported a higher percentage of irritable bowel syndrome (IBS), depression, anxiety, somatic symptoms, perceived stress, and insomnia compared to MYA. Patients with FM had more IBS, depression, and somatic symptom disorder versus MFP. After adjusting for confounding variables, participants with anxiety, somatic symptoms disorder, pain catastrophizing, and perceived stress, as well as a greater number of comorbidities, were more likely to have MFP than MYA, whereas FM participants were more associated with IBS, somatic symptoms and insomnia compared to MFP. The number of comorbidities was significantly associated with widespread pain but not pain duration, body mass index or being on sick leave. In conclusion, patients with MFP were more similar to those with FM regarding comorbidity and should be differentiated from MYA in clinical settings and pain management.

Prognostic factor analysis in patients with temporomandibular disorders after reversible treatment: study protocol for a prospective cohort study in China

INTRODUCTION

Temporomandibular disorders (TMDs) are complex multifactorial disorders. Reversible treatment has been suggested for the initial management of TMD; however, comparable therapeutic effects of different reversible intervention modalities remain controversial. Various biopsychosocial factors, which may be putative prognostic factors that influence the response to reversible treatment for TMD, have been reported to increase the risk of developing first-onset TMD. However, there is a paucity of research that aims to identify prognostic factors associated with the clinical outcomes of reversible treatment in people with TMD. The objective of this prospective cohort study is to identify prognostic factors that are associated with clinical outcomes of reversible treatment in patients with TMD and to analyse the risk factors that influence the development of chronic TMD.

METHODS AND ANALYSIS

We plan to recruit 834 patients with TMD who meet the inclusion criteria. Once informed consent is obtained, baseline data, including anamnestic data, physical assessments and self-report questionnaires, will be collected from participants at their first clinic visit; subsequently, they will receive 1-4 weeks of reversible treatment. The primary treatment outcome measures will be a change in the anterior maximum mouth opening, worsening of TMD pain scores assessed using a visual analogue scale (VAS) and a reduction in characteristic pain intensity. A good outcome will be defined as an anterior maximal opening ≥35 mm and at least a 30% reduction in VAS scores 3 months after baseline. The association between candidate prognostic factors and clinical outcomes of reversible TMD treatment will be analysed.

ETHICS AND DISSEMINATION

The protocol has been approved by the Ethics Committee of Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China, based on the guidelines outlined in the Declaration of Helsinki (SH9H-2019-T316-4). The results of this study will be reported in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology statement. The authors intend to publish the results in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ChiCTR2000033328.

Chronic Orofacial Pain: Models, Mechanisms, and Genetic and Related Environmental Influences

Chronic orofacial pain conditions can be particularly difficult to diagnose and treat because of their complexity and limited understanding of the mechanisms underlying their aetiology and pathogenesis. Furthermore, there is considerable variability between individuals in their susceptibility to risk factors predisposing them to the development and maintenance of chronic pain as well as in their expression of chronic pain features such as allodynia, hyperalgesia and extraterritorial sensory spread. The variability suggests that genetic as well as environmental factors may contribute to the development and maintenance of chronic orofacial pain. This article reviews these features of chronic orofacial pain, and outlines findings from studies in animal models of the behavioural characteristics and underlying mechanisms related to the development and maintenance of chronic orofacial pain and trigeminal neuropathic pain in particular. The review also considers the role of environmental and especially genetic factors in these models, focussing on findings of differences between animal strains in the features and underlying mechanisms of chronic pain. These findings are not only relevant to understanding underlying mechanisms and the variability between patients in the development, expression and maintenance of chronic orofacial pain, but also underscore the importance for considering the strain of the animal to model and explore chronic orofacial pain processes.

Transitioning to chronic temporomandibular disorder pain: A combination of patient vulnerabilities and iatrogenesis

Background

Based on a variety of studies conducted in recent years, some of the factors that might contribute to the negative treatment responses of some TMD patients have been elucidated.

Methods

This paper describes known vulnerability factors that make individuals susceptible to developing temporomandibular disorders (TMDs), as well as those that contribute to the perpetuation of such problems. In addition, the topic of iatrogenesis is discussed as a major contributor to the negative outcomes that can be seen in this field.

Results

At the patient level, anatomical, psychosocial and genetic factors may contribute to individual vulnerability. The anatomy and pathophysiology of muscles, joints, disc and nerves may all be involved in predisposing to TMD symptoms, especially when the patients have pain elsewhere in the body. Among the psychosocial factors, some features may be elucidated by the DC/TMD axis II, while others (eg illness behaviour, Munchausen syndrome, lack of acceptance of non‐mechanical approaches) require careful evaluation by trained clinicians. Genetic predisposition to first onset TMDs and to chronification of symptoms has been identified for individuals with certain psychological traits, presence of comorbid conditions and certain abnormal clinical manifestations. Regarding iatrogenesis, sins of omission may influence the clinical picture, with the main ones being misdiagnosis and undertreatment. Joint repositioning strategies, occlusal modifications, abuse of oral appliances, use of diagnostic technologies, nocebo effect and complications with intracapsular treatments are the most frequent sins of commission that may contribute to chronification of TMDs. The patients who present with massive occlusal and jaw repositioning changes combined with persistent severe orofacial pain are not a rarity within TMD and orofacial pain canters; these patients are the most difficult ones to manage because of this horrific combination of negative factors.

Conclusions

The information presented in this paper will help clinicians to understand better why some individuals develop temporomandibular disorders, why some of them will progress to becoming chronic patients, and what the appropriate responses may be.

Exercise Reduces Pain and Deleterious Histological Effects in Fibromyalgia-like Model

Fibromyalgia (FM) is characterized by chronic pain and associated comorbidities such as fatigue, anxiety, depression, and sleep disorders. There is a large amount of evidence regarding the benefits of physical exercise in controlling chronic pain. However, there is no consensus on which exercise modality is most suitable and the real benefits of this intervention to treat FM symptoms. The present study investigated the analgesic and antidepressant effects and morphophysiological responses induced by different physical exercise (aerobic and strength protocols) during the experimental model of FM. Spontaneous pain, mechanical hyperalgesia, thermal allodynia, depression-related behavior, and locomotor activity were evaluated weekly, as well as the morphological evaluation of the spinal cord and dorsal root ganglion. Aerobic and strength training protocols consistently abolished nociceptive behaviors, reducing spontaneous pain scores, cold allodynia, and frequency of response to mechanical hyperalgesia. The strength exercise modulated the depressive-like behavior. Finally, our data demonstrated that physical exercise performed for two weeks increased the number of glial cells in the dorsal root horn. However, it was not sufficient to control the other deleterious effects of the reserpine model on the spinal cord and the dorsal root. Together, these results demonstrated that different physical exercise modalities, when performed regularly in mice, proved to be effective and safe non-pharmacological alternatives for the treatment of FM. However, some gaps have yet to be studied regarding the neuroadaptive effects of physical exercise.