Relationship between temporomandibular disorders, widespread palpation tenderness, and multiple pain conditions: a case-control study

Is low back pain a risk/prognostic factor for the development and/or progression of temporomandibular disorders? A systematic review with meta-analysis

OBJECTIVES

To evaluate the association between low back pain (LBP) and painful temporomandibular disorders (TMDs).

METHODS

Systematic review of observational studies. Searches were conducted using OVID MEDLINE, CINHAL, Web of Science and PUBMED databases up to 21 October 2022. Qualitative and quantitative analyses were performed. Risk of bias (RoB) was assessed using the Quality in Prognosis Studies tool (QUIPS).

RESULTS

Eight studies were included in the present review with meta-analysis. The first onset of TMDs was more likely in patients with previous chronic LBP (hazard ratio (HR) 1.53 [95% confidence interval (CI): 1.28; 1.83, p < .00001]). In addition, patients with chronic LBP had 3.25 times the odds (OR) [95% CI: 1.94; 5.43, p < .00001] of having chronic TMDs than those who did not have chronic LBP. In addition, the higher the exposure to chronic LBP, the higher the risk of developing a first onset of TMDs.

CONCLUSIONS

Chronic LBP can be considered a risk/contributing factor for painful TMDs. Although there is a high certainty in the evidence linking chronic LBP with the risk of a first onset of TMDs, there are insufficient studies to draw definitive conclusions. Furthermore, while an association between chronic LBP and chronic TMDs and a dose-effect was observed between these two conditions, a limited number of studies and evidence exist to support these findings. Future studies are needed to increase the body of evidence.

Clinical features of chronic primary pain in individuals presenting painful temporomandibular disorder and comorbidities

BACKGROUND

The diagnosis of chronic primary pain (CPP), according to the recently released International Classification of Disease (ICD-11) criteria, refers to conditions with complex aetiologies. CPP is characterized by specific clinical features such as generalized sensory hypersensitivity and widespread pain, and is associated with functional disability and emotional distress.

OBJECTIVE

This study investigated clinical features of CPP in individuals with painful temporomandibular disorders (TMD) and comorbidities (fibromyalgia, migraine and/or tension-type headache).

METHODS

This cross-sectional study was conducted with a sample of 129 individuals. Painful TMD, fibromyalgia and primary headaches were evaluated based on well-established international criteria. Generalized sensory hypersensitivity was assessed using psychophysical tests. Symptoms of anxiety and depression were assessed by the Generalized Anxiety Disorder-7 and Patient Health Questionnaire-9. The Central Sensitization Inventory was applied to assess central sensitization-related symptoms and the Pittsburg Sleep Quality Index to evaluate the quality of sleep. The presence of widespread pain was assessed using a body map. The sample was stratified into three groups: control (n = 25), TMD-painful TMD only (n = 35) and TMD + Cm-painful TMD and comorbidities (n = 69). Statistical analysis was performed using one-way ANOVA, chi-squared test and ANCOVA, considering gender as a covariate (α = .05).

RESULTS

Compared to controls, individuals presenting painful TMD and comorbidities showed lower pressure pain thresholds in all evaluated areas (p ≤ .012) and a higher number of painful areas in the body (p = .001). They presented more symptoms of anxiety (p = .040) and depression (p = .018), and a higher score in the Central Sensitization Inventory (p ≤ .006) than the other groups.

CONCLUSION

Individuals with painful TMD and comorbidities presented more clinical features of CPP compared to those affected by TMD only.

An Update on Temporomandibular Disorders (TMDs) and Headache

PURPOSE OF REVIEW

To provide an overview and highlight recent updates in temporomandibular disorders (TMDs) and their comorbidity with headache disorders regarding pathophysiology and management.

RECENT FINDINGS

In the last decade, there have been great advancements in the understanding of TMDs and their relationship with neurovascular pains such as headaches. Understanding of TMDs is necessary for the context of its comorbidity with primary headache disorders. The literature regarding management of these comorbidities is scarce but points to combination therapy including pharmacological and non-pharmacological approaches to optimize management. The use of CGRP receptor-targeted monoclonal antibodies or CGRP receptor antagonists should be explored for the management of chronic TMDs. It could also be used as a novel monotherapy or in combination with non-pharmacological approaches for TMDs' comorbidity with headache, particularly migraine. Research is needed to support evidence-based management protocols. A team involving neurology (headache medicine) and dentistry (orofacial pain) is critical for optimal management.

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.

BMP2 Is Required for Postnatal Maintenance of Osteochondral Tissues of the Temporomandibular Joint

OBJECTIVE

Bone morphogenetic protein 2 (BMP2) plays important roles in cartilage growth and development. Paradoxically, elevated levels of BMP2 leads to hypertrophic differentiation and osteoarthritis of cartilage. We examined the in vivo loss of BMP2 in cells expressing aggrecan of the mandibular condyle and knee.

DESIGN

Three-week-old BMP2 flox/flox-CreER-positive mice and their Cre-negative littermates were treated with tamoxifen and raised until 3 or 6 months. We also investigated the direct effects of BMP2 on chondrocytes in vitro. Cells from the mandibular condyle of mice were treated with recombinant human BMP2 (rhBMP2) or rhNoggin (inhibitor of BMP2 signaling).

RESULTS

Conditional deletion of BMP2 caused breakage of the cartilage integrity in the mandibular condyle of mice from both age groups, accompanied by a decrease in cartilage thickness, matrix synthesis, mineralization, chondrocyte proliferation, and increased expression of degeneration markers, while the effects at articular cartilage were not significant. In vitro results revealed that rhBMP2 increased chondrocyte proliferation, mineralization, and differentiation, while noggin induced opposite effects.

CONCLUSIONS

In conclusion, BMP2 is essential for postnatal maintenance of the osteochondral tissues of the mandibular condyle.

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.

Presence of widespread pain predicts comorbidities and treatment response in temporomandibular disorders patients

OBJECTIVES

Investigate the presence of widespread pain in a well-defined TMD group and analyze its interrelationship with various comorbidities. Also, longitudinally seek the difference in treatment response according to the presence of widespread pain.

SUBJECTS AND METHODS

The observational study involved 45 female TMD patients in their 20s. Patients were grouped into localized and widespread pain groups based on the widespread pain index (WPI ≥ 4). Clinical characteristics and levels of comorbidities were analyzed through physical examination and validated questionnaires. Differences between the groups and the power of pre-treatment WPI in predicting pre-treatment comorbidities and post-treatment pain level improvement were statistically analyzed.

RESULTS

Patients with widespread pain showed higher somatization and anxiety levels. SF-36 scores were significantly lower and more patients complained of gastrointestinal symptoms. Conventional treatment significantly reduced pain intensity in both groups but less in the widespread pain group. WPI showed significant chances to predict patients showing improvement in pain levels with treatment with a cutoff value of 4. WPI was also effective in differentiating patients that showed a higher level of somatization.

CONCLUSION

Widespread pain index could be effectively applied in differentiating those with a higher level of psychological distress and predicting TMD treatment response with further investigations into its reliability.

The Relationship Between Clinical and Quantitative Measures of Pain Sensitization in Knee Osteoarthritis

OBJECTIVES

Pain sensitization in knee osteoarthritis (OA) is associated with greater symptom severity and poorer clinical outcomes. Measures that identify pain sensitization and are accessible to use in clinical practice have been suggested to enable more targeted treatments. This merits further investigation. This study examines the relationship between quantitative sensory testing (QST) and clinical measures of pain sensitization in people with knee OA.

METHODS

A secondary analysis of data from 134 participants with knee OA was performed. Clinical measures included: manual tender point count (MTPC), the Central Sensitization Inventory (CSI) to capture centrally mediated comorbidities, number of painful sites on a body chart, and neuropathic pain-like symptoms assessed using the modified PainDetect Questionnaire. Relationships between clinical measures and QST measures of pressure pain thresholds (PPTs), temporal summation, and conditioned pain modulation were investigated using correlation and multivariable regression analyses.

RESULTS

Fair to moderate correlations, ranging from -0.331 to -0.577 (P<0.05), were identified between MTPC, the CSI, number of painful sites, and PPTs. Fair correlations, ranging from 0.28 to 0.30 (P<0.01), were identified between MTPC, the CSI, number of painful sites, and conditioned pain modulation. Correlations between the clinical and self-reported measures and temporal summation were weak and inconsistent (0.09 to 0.25). In adjusted regression models, MTPC was the only clinical measure consistently associated with QST and accounted for 11% to 12% of the variance in PPTs.

DISCUSSION

MTPC demonstrated the strongest associations with QST measures and may be the most promising proxy measure to detect pain sensitization clinically.

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.

Widespread bodily pain is not associated with the presence of painful TMJ osteoarthritis: a case control study

Purpose: Temporomandibular Joint Arthralgia (TMJA) in the absence of osteoarthritis has not been thoroughly studied. We aimed to investigate the presence of comorbid bodily pain conditions (CBPC) in patients with TMJA with and without TMJOA and hypothesized that TMJOA is not associated with a higher presence of CBPC. Methods: This is a retrospective study involving patients at the University of North Carolina Orofacial Pain Clinic between 2010 and 2014 with TMJA according to the RDC/TMD criteria [1]. Cases fulfilled the Ahmad classification for TMJOA [2], and had TMJA (TMJA+OA), while controls had TMJA only (TMJA-OA). Data was collected from reports of Cone-Beam Computerized Tomography (CBCT). CBPC were self-reported. Results: Twenty-eight cases (TMJA+OA) and 25 controls (TMJA-OA) were included. The mean age of cases and controls (P = 0.027) and mean pain duration differed (P = 0.031). However, the gender distribution (P = 0.552), mean pain intensity (P = 0.381), mean number of painful muscles upon palpation (P = 0.759) and mean number of CBPC (P = 0.575) were not different. At least one CBPC was reported by 68% cases and 72% control subjects (P = 0.743). Conclusions: In this group of patients with TMJA, the presence of CBPC was high and not associated with the presence of TMJOA. This finding suggests that CBPC and TMJOA occur independently.

Understanding the relationship between features associated with pain-related disability in people with painful temporomandibular disorder: an exploratory structural equation modeling approach

Pain-related disability is a multifaceted construct that refers to the impact of pain on an individual's capacity to fulfill their self-defined and social roles. This research examined the relationship between clinical, psychological, and pain sensitivity factors and pain-related disability among adults with chronic temporomandibular disorder (TMD). We analyzed data from a cross-sectional community-based sample of 1088 men and women with chronic TMD. We first constructed and tested a measure of pain-related disability (ie, pain impact), including a variable assessing presenteeism, created measurement models of jaw limitation, psychological unease (negative affect, somatic symptoms, and catastrophizing), and experimental pain sensitivity (eg, pressure pain threshold, thermal tolerance, and mechanical pressure pain threshold). Subsequently, latent variables were combined in a structural equation model. Participants (n = 1088) were 18 to 44 years old (mean 29.2, SD ± 7.8) whose chronic TMD had persisted, on average, for 6.9 years (SD ± 6.4). A model of pain-related disability, jaw limitation, and psychological unease was created and refined with exploratory model revisions to account for correlation among variables. Estimation of the final model indicated excellent fit with the data (root-mean-square error of approximation = 0.048, root-mean-square error of approximation 90% confidence interval [CI] 0.043-0.053, comparative fit index = 0.956, standardized root-mean-square residual = 0.040). Jaw functional limitation and psychological unease was strongly related to pain-related disability. Experimental pain sensitivity was removed from our model because of weak direct effect and the burden of performing experimental pain sensitivity testing in a clinical setting. The final model explained 78% of the variance in pain-related disability.

Efficacy and safety of propranolol for treatment of temporomandibular disorder pain: a randomized, placebo-controlled clinical trial

Propranolol is a nonselective beta-adrenergic receptor antagonist. A multicenter, randomized, double-blind, placebo-controlled, parallel-group, phase 2b trial enrolled participants aged 18 to 65 years with temporomandibular disorder myalgia to evaluate efficacy and safety of propranolol compared with placebo in reducing facial pain. Participants were randomized 1:1 to either extended-release propranolol hydrochloride (60 mg, BID) or placebo. The primary endpoint was change in facial pain index (FPI = facial pain intensity multiplied by facial pain duration, divided by 100). Efficacy was analyzed as a mean change in FPI from randomization to week 9 and as the proportion of participants with ≥30% or ≥50% reductions in FPI at week 9. Regression models tested for treatment-group differences adjusting for study site, sex, race, and FPI at randomization. Of 299 participants screened, 200 were randomized; 199 had at least one postrandomization FPI measurement and were included in intention-to-treat analysis. At week 9, model-adjusted reductions in mean FPI did not differ significantly between treatment groups (-1.8, 95% CL: -6.2, 2.6; P = 0.41). However, the proportion with a ≥30% reduction in FPI was significantly greater for propranolol (69.0%) than placebo (52.6%), and the associated number-needed-to-treat was 6.1 (P = 0.03). Propranolol was likewise efficacious for a ≥50% reduction in FPI (number-needed-to-treat = 6.1, P = 0.03). Adverse event rates were similar between treatment groups, except for more frequent fatigue, dizziness, and sleep disorder in the propranolol group. Propranolol was not different from placebo in reducing mean FPI but was efficacious in achieving ≥30% and ≥50% FPI reductions after 9 weeks of treatment among temporomandibular disorder participants.

Association of decrease in insula fMRI activation with changes in trait anxiety in patients with craniomandibular disorder (CMD)

Patients with chronic pain and especially with craniomandibular disorder (CMD) show specific psychopathology in trait anxiety. In a previous longitudinal functional imaging study on CMD we found that the anterior insula was modulated by successful therapy intervention and pain relief. We here intended to investigate possible associations between anterior insula fMRI-activation during occlusal movements and trait anxiety over a splint therapy approach in patients with CMD. Three fMRI-investigations of a craniomandibular occlusion task were performed together with pain score evaluations and scoring of trait anxiety (State -Trait Anxiety Inventory; STAI) before, after two weeks and after three months of a DIR-mandibular splint therapy in a small group (n = 9) of CMD patients. Patients showed increased anxiety levels before therapy assessed with the STAI and the depression and anxiety scale (DASS). Besides of relevant reduction in pain the STAI decreased over time. Reduction in STAI was associated with anterior insular fMRI-activation reduction on both hemispheres. We conclude that the anxiety driven anticipation of pain related to occlusal trigger is processed in the anterior insula and might therefore be a main driver of therapeutic intervention by the splint therapy in CMD.

Perceived helpfulness of treatments for myofascial TMD as a function of comorbid widespread pain

OBJECTIVE

This study examined whether patients with myofascial temporomandibular disorder (mTMD) comorbid with fibromyalgia (FM) receive different treatments or respond differently to these treatments than mTMD-only patients.

MATERIALS AND METHODS

A total of 125 mTMD+ women were enrolled (26 FM+ and 98 FM-). mTMD and FM were assessed via clinical research examinations. Treatment histories and self-reported treatment-related improvement were obtained via interview.

RESULTS

The top 3 most common treatments reported were oral appliances (59%), physical therapy (54%), and jaw exercises at home (34%). Use of alternative medicine was reported more frequently among FM+ women, but self-reported improvement did not differ by comorbid FM. Physical therapy was as likely reported by FM status but self-reported improvement scores trended higher for FM+ women.

CONCLUSIONS

Oral appliances were as likely to be reported by FM comorbid as FM- women. Oral appliances did not outperform self-management treatments on self-reported improvement of facial pain.

CLINICAL RELEVANCE

Results support the use of self-management as first-line treatment for mTMD and potential utility of inquiring about widespread pain for treatment planning.

Spectroscopic differences in posterior insula in patients with chronic temporomandibular pain

Background and aims Chronic pain including temporomandibular disorder (TMD) pain involves a complex interplay between peripheral and central sensitization, endogenous modulatory pathways, cortical processing and integration and numerous psychological, behavioral and social factors. The aim of this study was to compare spectroscopic patterns of N-Acetyl-aspartate (NAA), total creatine (tCr), choline (Cho), myo-inositol (MI), glutamate (Glu), and the combination of Glu and glutamine in the posterior insula in patients with chronic generalized or regional chronic TMD pain (gTMD and rTMD, respectively) compared to healthy individuals (HI) in relation to clinical findings of TMD pain. Methods Thirty-six female patients with chronic rTMD or gTMD with at least 3 months duration were included in the study. Ten healthy women were included as controls. All participants completed a questionnaire that comprised assessment of degrees of depression, anxiety, stress, catastrophizing, pain intensity, disability and locations. A clinical Diagnostic Criteria for Temporomandibular Disorders examination that comprised assessment of pain locations, headache, mouth opening capacity, pain on mandibular movement, pain on palpation and temporomandibular joint noises was performed. Pressure-pain threshold (PPT) over the masseter muscle and temporal summation to pressure stimuli were assessed with an algometer. Within a week all participants underwent non-contrast enhanced MRI on a 3T MR scanner assessing T1-w and T2-w fluid attenuation inversion recovery. A single-voxel 1H-MRS examination using point-resolved spectroscopy was performed. The metabolite concentrations of NAA, tCr, Cho, MI, Glu and Glx were analyzed with the LC model. Metabolite levels were calculated as absolute concentrations, normalized to the water signal. Metabolite concentrations were used for statistical analysis from the LC model if the Cramér-Rao bounds were less than 20%. In addition, the ratios NAA/tCr, Cho/tCr, Glu/tCr and MI/tCr were calculated. Results The results showed significantly higher tCr levels within the posterior insula in patients with rTMD or gTMD pain than in HI (p=0.029). Cho was negatively correlated to maximum mouth opening capacity with or without pain (rs=-0.42, n=28, p=0.031 and rs=-0.48, n=28, p=0.034, respectively) as well as pressure-pain threshold on the hand (rs=-0.41, n=28, p=0.031). Glu was positively correlated to temporal summation to painful mechanical stimuli (rs=0.42, n=26, p=0.034). Conclusions The present study found that increased concentrations of Cho and Glu in the posterior insular cortex is related to clinical characteristics of chronic TMD pain, including generalized pain. These findings provide new evidence about the critical involvement of the posterior insular cortex and the neurobiology underlying TMD pain in both regional and generalized manifestations. Implications The findings in this study have indirect implications for the diagnosis and management of TMD patients. That said, the findings provide new evidence about the critical involvement of the posterior insular cortex and the neurobiology underlying TMD pain in both regional and generalized manifestations. It is also a further step towards understanding and accepting chronic pain as a disorder in itself.

Painful temporomandibular disorders (TMD) and comorbidities in primary care: associations with pain-related disability

Objective: We studied whether primary care temporomandibular disorder (TMD) patients reporting different levels of pain-related disability differ in terms of comorbid pains, general health conditions and quality of life.Material and methods: Consecutive TMD pain patients (n = 399) seeking treatment in primary care completed a questionnaire on comorbid pains and their interference and the Finnish version of the RAND-36-item quality of life questionnaire. Medical diagnoses confirmed by doctors were recorded. The patients were classified according to the Graded Chronic Pain Scale (GCPS) of the Research Diagnostic Criteria for TMD (RDC/TMD). The patients were classified: no disability group (0 disability points), low disability group (1-2 disability points) and high disability group (3-6 disability points).Results: Compared to patients in the no-disability group, patients in the high- and low-disability groups reported more comorbid pain conditions (p < .001), and experienced these as more intense and interfering more with daily life (p < .05). Patients in the high-disability group reported more general health-related medical diagnoses than patients in the no-disability group (p < .05). Furthermore, patients with low or high pain-related disability indicated poorer quality of life in all RAND-36 subscales than those with no disability (p < .05).Conclusions: The findings suggest that GCPS-related disability scoring can be used as a simple screening instrument to identify TMD patients with different degrees of health burdens.

Similar treatment outcome in myofascial TMD patients with localized and widespread pain

OBJECTIVE

To study the outcome of oral appliance treatment in myofascial Temporomandibular disorder (TMD) patients with and without comorbid pain using pain site drawings.

MATERIAL AND METHODS

This randomized, controlled multicentre study comprised 65 myofascial TMD patients diagnosed according to the Research Diagnostic Criteria for Temporomandibular Disorders. Pain-site drawings were filled in at the baseline examination. The patients were treated with oral appliances. Treatment outcome was followed up for 1 year and analysed according to the recommendations by the Initiative on Methods, Measurement and Pain assessment in Clinical Trials (IMMPACT) on an intent-to-treat basis. The data were analysed for two pain profiles, localized pain (face and head, n = 26) versus widespread pain group (pain sites outside the face and head, n = 39).

RESULTS

Statistically significant improvement was registered within both groups for all outcome variables (characteristic pain intensity, 30% pain reduction of worst reported pain, graded chronic pain, depression, and somatization scores) during the follow-up with only small differences between the groups.

CONCLUSIONS

Oral appliance treatment had a positive effect on all outcome measures during the 1-year follow-up in patients suffering from myofascial TMD pain, regardless of whether the pain was localized or widespread. Multiple pain sites seemed to have surprisingly little influence on the outcome variables. However, some indications of more challenges when treating patients with widespread pain compared to local pain could be observed. Pain-site drawings seem to be useful in the clinical situation and could support the clinicians in decision-making regarding treatment planning.

As if one pain problem was not enough: prevalence and patterns of coexisting chronic pain conditions and their impact on treatment outcomes

INTRODUCTION

The presence of multiple coexisting chronic pain (CP) conditions (eg, low-back pain and migraines) within patients has received little attention in literature. The goals of this observational longitudinal study were to determine the prevalence of coexisting CP conditions, identify the most frequent ones and patterns of coexistence, investigate the relationships among patients' biopsychosocial characteristics and number of CP conditions, and determine the impact of coexisting CP conditions on treatment response.

PATIENTS AND METHODS

A total of 3,966 patients attending multidisciplinary pain-treatment centers who were enrolled in the Quebec Pain Registry were included. Patients completed self-report and nurse-administered questionnaires before their first visit and 6 months later. Results were analyzed using descriptive statistics, factor and cluster analyses, negative binomials with log-link generalized linear models, and linear mixed-effect models.

RESULTS

A third of patients reported coexisting CP conditions. No specific patterns of comorbidities emerged. The presence of coexisting CP conditions was associated with longer pain duration, older age, being female, and poorer quality of life. The presence of more than one CP condition did not have a clinically significant impact on treatment responses.

DISCUSSION

The novelty of the study results relate to the heterogeneity that was found in the patterns of coexistence of CP conditions and the fact that having multiple CP conditions did not clinically impact treatment response. These results highlight the need for future research that examines causes of coexistence among CP conditions across the spectrum of CP, as opposed to focusing on specific conditions, and to examine whether multiple CP conditions impact on additional domains, such as treatment satisfaction. These results highlight the importance of studying the pathophysiological mechanisms underlying the development of coexisting CP conditions, in order eventually to prevent/minimize their occurrence and/or develop optimal treatment and management approaches.

The effect of supervised exercise on localized TMD pain and TMD pain associated with generalized pain

OBJECTIVES

To evaluate the effect of a supervised exercise program in patients with localized/regional temporomandibular disorder (TMD) pain and with TMD associated with generalized pain.

MATERIAL AND METHODS

Consecutively referred patients with localized/regional TMD pain (n = 56; 46 women and 10 men, mean age 44 years) and TMD associated with generalized pain (n = 21; 21 women, mean age 41 years) participated. Patients underwent a 10-session structured supervised exercise program over 10-20 weeks that included relaxation, and coordination and resistance training of the jaw and neck/shoulders. The outcomes were jaw pain intensity on the Numerical Rating Scale, endurance time for jaw opening and protrusion against resistance and chewing, and effect of pain on daily activities.

RESULTS

After the exercise program, a reduction in jaw pain was reported by the local (p = .001) and general (p = .011) pain groups. There were no significant differences in jaw pain intensity between the groups, before (p = .062) or after treatment (p = .121). Endurance time increased for both groups for jaw opening/protrusion (both p < .001) and chewing (both p = .002). The effect of jaw pain on daily activities decreased after exercise compared to baseline for both the local (p < .001) and general (p = .008) pain groups.

CONCLUSIONS

Supervised exercise can reduce TMD pain and increase capacity in patients with TMD. The results suggest that activation of the jaw motor system with exercise has a positive effect in patients with localized/regional TMD pain and TMD associated with generalized pain.

Alterations in opioid inhibition cause widespread nociception but do not affect anxiety-like behavior in oral cancer mice

Widespread pain and anxiety are commonly reported in cancer patients. We hypothesize that cancer is accompanied by attenuation of endogenous opioid-mediated inhibition, which subsequently causes widespread pain and anxiety. To test this hypothesis we used a mouse model of oral squamous cell carcinoma (SCC) in the tongue. We found that mice with tongue SCC exhibited widespread nociceptive behaviors in addition to behaviors associated with local nociception that we reported previously. Tongue SCC mice exhibited a pattern of reduced opioid receptor expression in the spinal cord; intrathecal administration of respective mu (MOR), delta (DOR), and kappa (KOR) opioid receptor agonists reduced widespread nociception in mice, except for the fail flick assay following administration of the MOR agonist. We infer from these findings that opioid receptors contribute to widespread nociception in oral cancer mice. Despite significant nociception, mice with tongue SCC did not differ from sham mice in anxiety-like behaviors as measured by the open field assay and elevated maze. No significant differences in c-Fos staining were found in anxiety-associated brain regions in cancer relative to control mice. No correlation was found between nociceptive and anxiety-like behaviors. Moreover, opioid receptor agonists did not yield a statistically significant effect on behaviors measured in the open field and elevated maze in cancer mice. Lastly, we used an acute cancer pain model (injection of cancer supernatant into the mouse tongue) to test whether adaptation to chronic pain is responsible for the absence of greater anxiety-like behavior in cancer mice. No changes in anxiety-like behavior were observed in mice with acute cancer pain.

Characterization of Whole Body Pain in Urological Chronic Pelvic Pain Syndrome at Baseline: A MAPP Research Network Study

PURPOSE

We characterized the location and spatial distribution of whole body pain in patients with urological chronic pelvic pain syndrome using a body map. We also compared the severity of urinary symptoms, pelvic pain, nonpelvic pain and psychosocial health among patients with different pain patterns.

MATERIALS AND METHODS

A total of 233 women and 191 men with urological chronic pelvic pain syndrome enrolled in a multicenter, 1-year observational study completed a battery of baseline measures, including a body map describing the location of pain during the last week. Participants were categorized with pelvic pain if they reported pain in the abdomen and pelvis only. Participants who reported pain beyond the pelvis were further divided into 2 subgroups based on the number of broader body regions affected by pain, including an intermediate group with 1 or 2 additional regions outside the pelvis and a widespread pain group with 3 to 7 additional regions.

RESULTS

Of the 424 enrolled patients 25% reported pelvic pain only and 75% reported pain beyond the pelvis, of whom 38% reported widespread pain. Participants with a greater number of pain locations had greater nonpelvic pain severity (p <0.0001), sleep disturbance (p = 0.035), depression (p = 0.005), anxiety (p = 0.011), psychological stress (p = 0.005) and negative affect scores (p = 0.0004), and worse quality of life (p ≤0.021). No difference in pelvic pain and urinary symptom severity was observed according to increasing pain distribution.

CONCLUSIONS

Three-quarters of the men and women with urological chronic pelvic pain syndrome reported pain outside the pelvis. Widespread pain was associated with greater severity of nonpelvic pain symptoms, poorer psychosocial health and worse quality of life but not with worse pelvic pain or urinary symptoms.

Influence of culture on pain comorbidity in women with and without temporomandibular disorder-pain

Evidence on cultural differences in prevalence and impact of common chronic pain conditions, comparing individuals with temporomandibular disorders (TMD) versus individuals without TMD, is limited. The aim was to assess cross-cultural comorbid pain conditions in women with chronic TMD pain. Consecutive women patients (n = 122) with the index condition of chronic TMD pain diagnosed per the research diagnostic criteria for TMD and TMD-free controls (n = 121) matched for age were recruited in Saudi Arabia, Italy and Sweden. Self-report questionnaires assessed back, chest, stomach and head pain for prevalence, pain intensity and interference with daily activities. Logistic regression was used for binary variables, and ancova was used for parametric data analysis, adjusting for age and education. Back pain was the only comorbid condition with a different prevalence across cultures; Swedes reported a lower prevalence compared to Saudis (P < 0·01). Saudis reported higher prevalence of work reduced >50% due to back pain compared to Italians or Swedes (P < 0·01). Headache was the most common comorbid condition in all three cultures. The total number of comorbid conditions did not differ cross-culturally but were reported more by TMD-pain cases than TMD-free controls (P < 0·01). For both back and head pain, higher average pain intensities (P < 0·01) and interference with daily activities (P < 0·01) were reported by TMD-pain cases, compared to TMD-free controls. Among TMD-pain cases, Italians reported the highest pain-related disability (P < 0·01). Culture influences the associated comorbidity of common pain conditions. The cultural influence on pain expression is reflected in different patterns of physical representation.

Identification of clusters of individuals relevant to temporomandibular disorders and other chronic pain conditions: the OPPERA study

The classification of most chronic pain disorders gives emphasis to anatomical location of the pain to distinguish one disorder from the other (eg, back pain vs temporomandibular disorder [TMD]) or to define subtypes (eg, TMD myalgia vs arthralgia). However, anatomical criteria overlook etiology, potentially hampering treatment decisions. This study identified clusters of individuals using a comprehensive array of biopsychosocial measures. Data were collected from a case-control study of 1031 chronic TMD cases and 3247 TMD-free controls. Three subgroups were identified using supervised cluster analysis (referred to as the adaptive, pain-sensitive, and global symptoms clusters). Compared with the adaptive cluster, participants in the pain-sensitive cluster showed heightened sensitivity to experimental pain, and participants in the global symptoms cluster showed both greater pain sensitivity and greater psychological distress. Cluster membership was strongly associated with chronic TMD: 91.5% of TMD cases belonged to the pain-sensitive and global symptoms clusters, whereas 41.2% of controls belonged to the adaptive cluster. Temporomandibular disorder cases in the pain-sensitive and global symptoms clusters also showed greater pain intensity, jaw functional limitation, and more comorbid pain conditions. Similar results were obtained when the same methodology was applied to a smaller case-control study consisting of 199 chronic TMD cases and 201 TMD-free controls. During a median 3-year follow-up period of TMD-free individuals, participants in the global symptoms cluster had greater risk of developing first-onset TMD (hazard ratio = 2.8) compared with participants in the other 2 clusters. Cross-cohort predictive modeling was used to demonstrate the reliability of the clusters.

Pain-Related Temporomandibular Disorder - Current Perspectives and Evidence-Based Management

Pain-related temporomandibular disorder (TMD) is one of the top three most common chronic pain conditions, along with headaches and back pain. TMD has complex pathophysiology and significant associations with a variety of other chronic pain conditions, eg fibromyalgia, irritable bowel syndrome and migraine. Chronic TMD is associated with a negative impact upon quality of life and high levels of healthcare utility. It is important that clinicians are able to diagnose TMD correctly, provide appropriate management in keeping with current evidence-based practice, and identify when to refer patients to specialist care. The presence of risk factors, eg anxiety, depression, pain-related disability and chronic pain conditions elsewhere in the body, may help to identify which TMD patients require referral for multidisciplinary management. TMD should be managed using a holistic approach, incorporating patient education and encouragement towards self-management. TMD care pathways should consider using the three'pillars'of pain management: physical therapies, pharmacotherapy and clinical psychology.

Temporomandibular Joint Hypermobility Manifestation Based on Clinical Observations

BACKGROUND

Joint range of motion might affected by some factors like laxity and increase joint mobility. Generalized joint hypermobility and temporomandibular joint hypermobility (TMJH) are reported as risk factors for temporomandibular disorders. The aim of this study was to survey the etiological factors of TMJH and its relations to habitual status.

MATERIALS AND METHODS

In this cross-sectional descriptive study, 69 patients with TMJH were involved. After profiling personal information and medical history, the patients were divided into three groups based on their maximum mouth opening (MMO) as follow: (Light) MMO of 50-55 mm, (moderate): MMO between 55 and 65 mm, (severe) MMO >65 mm. For subjective observations, patients were asked to fill the prepared questionnaire. The objective evaluations conducted by a specialist. Finally, all the data subjected Chi-Square test by using SPSS software version 22 at a significant level of 0.05.

RESULTS

TMJH was more common in women (74.2%). The light group had significant differences with other groups in the discomfort of TMJ and TMJ sound (P < 0.05). Furthermore, sever group manifested highest percentage of masticatory pains, significantly (P < 0.05).

CONCLUSION

It can be concluded that pain in TMJ would have a correlation with MMO.

Chronicity factors of temporomandibular disorders: a critical review of the literature

Facial pain often persists long after any identifiable organic pathology has healed. Moreover, in a subgroup of patients with temporomandibular disorder (TMD), no treatment is effective. Knowledge of factors associated with persistent pain in TMD could help identify personalized treatment approaches. Therefore, we conducted a critical review of the literature for the period from January 2000 to December 2013 to identify factors related to TMD development and persistence. The literature findings showed that chronic TMD is marked by psychological distress (somatization and depression, affective distress, fear of pain, fear of movement, and catastrophizing) and characteristics of pain amplification (hyperalgesia and allodynia). Furthermore, these factors seem to interact in TMD development. In addition, our review demonstrates that upregulation of the serotonergic pathway, sleep problems, and gene polymorphisms influence the chronicity of TMD. We conclude that psychological distress and pain amplification contribute to chronic TMD development, and that interactions among these factors complicate pain management. These findings emphasize the importance of multidisciplinary assistance in TMD treatment.

Are temporomandibular disorders associated with habitual sleeping body posture or nasal septal deviation?

Numerous factors can be considered for the etiology of temporomandibular disorders (TMD). The aim of the present study was to investigate whether the presence of both nasal septal deviation (NSD) and habitual prone sleeping posture (HPSP) predisposes TMD. We evaluated 200 subjects in 4 groups. Group I (NSD-, HPSP-/control group), Group II (NSD+, HPSP-), Group III (NSD-, HPSP+), Group IV (NSD+, HPSP+). All patients were examined according to the research diagnostic criteria to determine the presence of TMD. Group IV had the highest value for TMD incidence (44 %). Thus, we found that the presence of both NSD and HPSP parameters increased TMD incidence in Group IV compared to the control group (p = 0.000). Additionally, Group IV showed significantly higher values than Group II (p = 0.012) and Group III (p = 0.039). For Group III (NSD-, HPSP+), TMD was determined higher compared to the control group (p = 0.009). A statistically higher value of presence of TMD was determined in Group II (NSD+, HPSP-) than control group (p = 0.029). The incidence of TMD was significantly higher in women than men (p = 0.020). We concluded that one having an unilateral obstructive nasal septal deviation in addition to a habit of sleeping in prone position must be alert for potential TMD.

Epistasis between polymorphisms in COMT, ESR1, and GCH1 influences COMT enzyme activity and pain

Abnormalities in the enzymatic activity of catechol-O-methyltransferase (COMT) contribute to chronic pain conditions, such as temporomandibular disorders (TMD). Thus, we sought to determine the effects of polymorphisms in COMT and functionally related pain genes in the COMT pathway (estrogen receptor 1 [ESR1], guanosine-5-triphosphate cyclohydrolase 1 [GCH1], methylenetetrahydrofolate reductase [MTHFR]) on COMT enzymatic activity, musculoskeletal pain, and pain-related intermediate phenotypes among TMD cases and healthy control subjects. Results show that the COMT rs4680 (val(158)met) polymorphism is most strongly associated with outcome measures, such that individuals with the minor A allele (met) exhibit reduced COMT activity, increased TMD risk, and increased musculoskeletal pain. Epistatic interactions were observed between the COMT rs4680 polymorphism and polymorphisms in GCH1 and ESR1. Among individuals with the COMT met allele, those with 2 copies of the GCH1 rs10483639 minor G allele exhibit normalized COMT activity and increased mechanical pain thresholds. Among individuals with the COMT val allele, those with 2 copies of the ESR1 rs3020377 minor A allele exhibit reduced COMT activity, increased bodily pain, and poorer self-reported health. These data reveal that the GCH1 minor G allele confers a protective advantage among met carriers, whereas the ESR1 minor A allele is disadvantageous among val carriers. Furthermore, these data suggest that the ability to predict the downstream effects of genetic variation on COMT activity is critically important to understanding the molecular basis of chronic pain conditions.

Before the onset of interstitial cystitis/bladder pain syndrome, the presence of multiple non-bladder syndromes is strongly associated with a history of multiple surgeries

OBJECTIVE

Certain functional somatic syndromes (FSSs) such as fibromyalgia and irritable bowel syndrome are accompanied by diffuse pain amplification. Women with interstitial cystitis/bladder pain syndrome (IC/BPS) have numerous FSSs, as well as other non-bladder syndromes (NBSs) that are linked to the FSSs. They also report multiple surgeries. Since pain is a common indication for surgery, we tested the hypothesis that NBSs were associated with surgeries.

METHODS

We interviewed 312 incident IC/BPS cases and controls on NBSs and number of surgeries before the index date (for cases, IC/BPS onset date). Poisson and logistic regression analyses adjusted for age, race, educational level, and menopause.

RESULTS

Number of surgeries increased with number of NBSs in both cases and controls whether chronic pelvic pain (CPP), the only NBS generally accepted as an indication for surgery, was present or not. Logistic regression analysis showed that among cases CPP was the only individual NBS associated with a history of multiple surgeries, and then only modestly [odds ratio (OR) 1.9, confidence intervals (CI) 1.06, 3.2]. By far the strongest association was the number of NBSs. The OR for multiple surgeries increased with number of NBSs: for cases with 4-5 NBSs the OR was 14.1 (1.8, 113) and with 6-9 NBSs, 33.1 (3.9, 279). Controls had fewer syndromes and fewer surgeries and this linkage was less prominent.

CONCLUSION

Among IC/BPS cases, the number of NBSs was strongly correlated with the number of surgeries. Understanding temporal relationships will be necessary to explore causal linkages and may modify surgical practice.

Expanding the taxonomy of the diagnostic criteria for temporomandibular disorders

There is a need to expand the current temporomandibular disorders' (TMDs) classification to include less common but clinically important disorders. The immediate aim was to develop a consensus-based classification system and associated diagnostic criteria that have clinical and research utility for less common TMDs. The long-term aim was to establish a foundation, vis-à-vis this classification system, that will stimulate data collection, validity testing and further criteria refinement. A working group [members of the International RDC/TMD Consortium Network of the International Association for Dental Research (IADR), members of the Orofacial Pain Special Interest Group (SIG) of the International Association for the Study of Pain (IASP), and members from other professional societies] reviewed disorders for inclusion based on clinical significance, the availability of plausible diagnostic criteria and the ability to operationalise and study the criteria. The disorders were derived from the literature when possible and based on expert opinion as necessary. The expanded TMDs taxonomy was presented for feedback at international meetings. Of 56 disorders considered, 37 were included in the expanded taxonomy and were placed into the following four categories: temporomandibular joint disorders, masticatory muscle disorders, headache disorders and disorders affecting associated structures. Those excluded were extremely uncommon, lacking operationalised diagnostic criteria, not clearly related to TMDs, or not sufficiently distinct from disorders already included within the taxonomy. The expanded TMDs taxonomy offers an integrated approach to clinical diagnosis and provides a framework for further research to operationalise and test the proposed taxonomy and diagnostic criteria.

Type, rather than number, of mental and physical comorbidities increases the severity of symptoms in patients with irritable bowel syndrome

BACKGROUND & AIMS

Irritable bowel syndrome (IBS) has significant mental and physical comorbidities. However, little is known about the day-to-day burden these comorbidities place on quality of life (QOL), physical and mental function, distress, and symptoms of patients.

METHODS

We collected cross-sectional data from 175 patients with IBS, which was diagnosed on the basis of Rome III criteria (median age, 41 years; 78% women), who were referred to 2 specialty care clinics. Patients completed psychiatric interviews, a physical comorbidity checklist, the IBS Symptom Severity Scale, the IBS-QOL instrument, the Brief Symptom Inventory, the abdominal pain intensity scale, and the Short Form-12 Health Survey.

RESULTS

Patients with IBS reported an average of 5 comorbidities (1 mental, 4 physical). Subjects with more comorbidities reported worse QOL after adjusting for confounding variables. Multiple linear regression analyses indicated that comorbidity type was more consistently and strongly associated with illness burden indicators than disease counts. Of 10,296 possible physical-mental comorbidity pairs, 6 of the 10 most frequent dyads involved specific conditions (generalized anxiety, depression, back pain, agoraphobia, tension headache, and insomnia). These combinations were consistently associated with greater illness and symptom burdens (QOL, mental and physical function, distress, more severe symptoms of IBS, and pain).

CONCLUSIONS

Comorbidities are common among patients with IBS. They are associated with distress and reduced QOL. Specific comorbidities are associated with more severe symptoms of IBS.

Facial pain with localized and widespread manifestations: separate pathways of vulnerability

Human association studies of common genetic polymorphisms have identified many loci that are associated with risk of complex diseases, although individual loci typically have small effects. However, by envisaging genetic associations in terms of cellular pathways, rather than any specific polymorphism, combined effects of many biologically relevant alleles can be detected. The effects are likely to be most apparent in investigations of phenotypically homogenous subtypes of complex diseases. We report findings from a case-control, genetic association study of relationships between 2925 single nucleotide polymorphisms (SNPs) and 2 subtypes of a commonly occurring chronic facial pain condition, temporomandibular disorder (TMD): 1) localized TMD and 2) TMD with widespread pain. When compared to healthy controls, cases with localized TMD differed in allelic frequency of SNPs that mapped to a serotonergic receptor pathway (P=0.0012), while cases of TMD with widespread pain differed in allelic frequency of SNPs that mapped to a T-cell receptor pathway (P=0.0014). A risk index representing combined effects of 6 SNPs from the serotonergic pathway was associated with greater odds of localized TMD (odds ratio 2.7, P=1.3 E-09), and the result was reproduced in a replication case-control cohort study of 639 people (odds ratio 1.6, P=0.014). A risk index representing combined effects of 8 SNPs from the T-cell receptor pathway was associated with greater odds of TMD with widespread pain (P=1.9 E-08), although the result was not significant in the replication cohort. These findings illustrate potential for clinical classification of chronic pain based on distinct molecular profiles and genetic background.

Multisystem dysregulation in painful temporomandibular disorders

Multiple physiological and psychological regulatory domains may contribute to the pathophysiology of pain in temporomandibular disorder (TMD) and other bodily pain conditions. The purpose of this study was to evaluate the relationship between multisystem dysregulation and the presence of TMD pain, as well as the presence of different numbers of comorbid pain conditions in TMD. Secondary data analysis was conducted in 131 non-TMD (without comorbid pain) controls, 14 TMD subjects without comorbid pain, 78 TMD subjects with 1 comorbid pain, and 67 TMD subjects with multiple comorbid pain conditions who participated in a TMD genetic study. Twenty markers from sensory, autonomic, inflammatory, and psychological domains were evaluated. The results revealed that 1) overall dysregulation in multiple system domains (OR [odds ratio] = 1.6, 95% confidence interval [CI] = 1.4-1.8), particularly in the sensory (OR = 1.9, 95% CI = 1.3-2.9) and the psychological (OR = 2.1, 95% CI = 2.1-2.7) domains, were associated with increased likelihood of being a painful TMD case; and 2) dysregulations in individual system domains were selectively associated with the increased odds of being a TMD case with different levels of comorbid persistent pain conditions. These outcomes indicate that heterogeneous multisystem dysregulations may exist in painful TMD subgroups, and multidimensional physiological and psychological assessments can provide important information regarding pathophysiology, diagnosis, and management of pain in TMD patients.

PERSPECTIVE

The concurrent assessment of multiple physiological and psychological systems is critical to our understanding of the pathophysiological processes that contribute to painful TMD and associated comorbid conditions, which will ultimately guide and inform appropriate treatment strategies that address the multisystem dysregulation associated with complex and common persistent pain conditions.