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

Chronic orofacial pain and pharmacological management-a clinical guide

Orofacial pain is a widespread health concern that significantly hinders an individual's capacity to engage in daily activities. This type of pain can be classified into three main categories: nociceptive pain, neuropathic pain, and nociplastic pain. Each category involves different mechanisms and requires specific treatment approaches. For optimal treatment of orofacial pain disorders, a multidisciplinary pain management approach is essential. This approach should integrate both nonpharmacological and pharmacological modalities to address the diverse underlying causes and manifestations of pain. In this review, we focus on the current evidence and advancements in the pharmacological management of chronic orofacial pain. We explored the effectiveness of different medications, their mechanisms of action, and their role within a comprehensive pain management plan.

β-Blockers and risk of neuropsychiatric disorders: A systematic review and meta-analysis

AIMS

This systematic review and meta-analysis aimed to evaluate the association between β-blocker use and neuropsychiatric adverse events, specifically focusing on short-term outcomes.

METHODS

A comprehensive literature search identified studies reporting neuropsychiatric outcomes in patients using β-blockers, including randomized controlled trials and observational studies. Relative risks (RR) and 95% confidence intervals (CIs) were calculated for outcomes such as dizziness, insomnia, nightmares, drowsiness and delirium.

RESULTS

Our analysis revealed that β-blocker use was significantly associated with an increased risk of dizziness (RR 1.72, 95% CI [1.39-2.14]; I2 = 1%, 14 studies) compared to placebo. Lipophilic β-blockers, especially propranolol, showed an even greater risk of dizziness (RR 3.13, 95% CI [1.44-6.84]; I2 = 0%, three studies). Propranolol was also associated with increased insomnia risk compared to placebo (RR 1.13, 95% CI [1.00-1.28]; I2 = 0%, five studies). Our data did not show statistically significant increases in the reports of nightmares and somnolence. Other adverse effects, including drowsiness, sleep disturbances, hallucinations and delirium, were noted.

CONCLUSIONS

Our findings suggest a significant association between β-blocker use and an increased risk of neuropsychiatric adverse events, particularly insomnia and dizziness with higher risks associated with lipophilic β-blocker use. Given the ambiguity surrounding dizziness and its classification as a neuropsychiatric effect, our findings are exploratory, and we cannot exclude a potential cardiovascular origin for dizziness. Most studies (75%) were published before the CONSORT statement in 1996, indicating potential reporting limitations and a lack of recent research. Additionally, 60% of studies had a high risk of bias, underscoring the need for more rigorous and contemporary investigations into the neuropsychiatric implications of β-blocker use.

The effects of socioeconomic position on endogenous pain modulation: A quasi-experimental approach

Socioeconomic Position (SEP) is a multidimensional construct encompassing education, income, occupation, and neighborhood distress, influencing chronic pain severity, interference, and duration. However, its impact on placebo analgesia, where reduced pain perception occurs due to treatment belief, remains understudied. Using a quasi-experimental approach, we investigated SEP's influence on placebo analgesia in 401 participants with temporomandibular disorder (TMD) and 400 pain-free individuals. Using latent class analysis, we grouped participants into two SEP groups based on self-reported education, income, occupation, and neighborhood distress indices, including the area deprivation and distressed community indexes. Ancestry Informative Markers (AIMs) and self-reported race were included to account for genetic and demographic influences. Placebo analgesia was elicited using verbal suggestion and classical conditioning. Linear mixed models were employed to analyze SEP's impact, while multiple regression and ANCOVA assessed AIMs' and race's effects. Comparable placebo effects were observed between participants with TMD and pain-free individuals (F(1,4765.73) = 0.49, p = 0.48). A trend was noted in the main effect of SEP (F(1,4764.5) = 3.64, p = 0.056). Among TMD participants, those with distressed SEP exhibited lower placebo analgesia (F(1,4765.73) = 7.9, p = 0.005), while placebo response did not differ by SEP in pain-free participants (F(1,4765.73) = 0.27, p = 0.59). East Asian ancestry (β = 5.71, 95% CI [1.50, 9.92]) and self-reported Asian (mean = 24.20, sem = 1.52, p = 0.020) were associated with greater placebo analgesia. This study highlights the interplay of SEP, AIMs, and race in placebo analgesia and calls for tailored pain management interventions. PERSPECTIVE: SEP significantly contributes to pain disparities. This quasi-experimental study demonstrates analogous placebo analgesia between chronic pain and pain-free individuals but finds lower placebo analgesia only among individuals with chronic pain and distressed SEP. This highlights a link between chronic pain, SEP, and impaired placebo effects, suggesting new avenues for research.

Effect of regional crosstalk between sympathetic nerves and sensory nerves on temporomandibular joint osteoarthritic pain

Temporomandibular joint osteoarthritis (TMJ-OA) is a common disease often accompanied by pain, seriously affecting physical and mental health of patients. Abnormal innervation at the osteochondral junction has been considered as a predominant origin of arthralgia, while the specific mechanism mediating pain remains unclear. To investigate the underlying mechanism of TMJ-OA pain, an abnormal joint loading model was used to induce TMJ-OA pain. We found that during the development of TMJ-OA, the increased innervation of sympathetic nerve of subchondral bone precedes that of sensory nerves. Furthermore, these two types of nerves are spatially closely associated. Additionally, it was discovered that activation of sympathetic neural signals promotes osteoarthritic pain in mice, whereas blocking these signals effectively alleviates pain. In vitro experiments also confirmed that norepinephrine released by sympathetic neurons promotes the activation and axonal growth of sensory neurons. Moreover, we also discovered that through releasing norepinephrine, regional sympathetic nerves of subchondral bone were found to regulate growth and activation of local sensory nerves synergistically with other pain regulators. This study identified the role of regional sympathetic nerves in mediating pain in TMJ-OA. It sheds light on a new mechanism of abnormal innervation at the osteochondral junction and the regional crosstalk between peripheral nerves, providing a potential target for treating TMJ-OA pain.

Use of patient-reported global assessment measures in clinical trials of chronic pain treatments: ACTTION systematic review and considerations

ABSTRACT

Establishing clinically meaningful changes in pain experiences remains important for clinical trials of chronic pain treatments. Regulatory guidance and pain measurement initiatives have recommended including patient-reported global assessment measures (eg, Patient-Global Impression of Change [PGIC]) to aid interpretation of within-patient differences in domain-specific clinical trial outcomes (eg, pain intensity). The objectives of this systematic review were to determine the frequency of global assessment measures inclusion, types of measures, domains assessed, number and types of response options, and how measures were analyzed. Of 4172 abstracts screened across 6 pain specialty journals, we reviewed 96 clinical trials of chronic pain treatments. Fifty-two (54.2%) studies included a global assessment measure. The PGIC was most common (n = 28; 53.8%), with relatively infrequent use of other measures. The majority of studies that used a global assessment measure (n = 31; 59.6%) assessed change or improvement in an unspecified domain. Others assessed overall condition severity (n = 9; 17.3%), satisfaction (n = 8; 15.4%), or overall health status/recovery (n = 5; 9.6%). The number, range, and type of response options were variable and frequently not reported. Response options and reference periods even differed within the PGIC. Global assessment measures were most commonly analyzed as continuous variables (n = 24; 46.2%) or as dichotomous variables with positive categories combined to calculate the proportion of participants with a positive response to treatment (n = 18; 34.6%). This review highlights the substantial work necessary to clarify measurement and use of patient global assessment in chronic pain trials and provides short- and long-term considerations for measure selection, reporting and analysis, and measure development.

Effect of acupuncture for temporomandibular disorders: a randomized clinical trial

BACKGROUND

Temporomandibular disorders (TMD) are the leading cause of pain and disability among frequently occurring facial pain and the second leading cause of musculoskeletal conditions.

AIM

We examined whether acupuncture could alleviate pain intensity in patients with TMD.

DESIGN AND METHODS

Sixty participants with TMD were randomly assigned (ratio 1:1) to receive three acupuncture or sham acupuncture sessions weekly for 4 weeks. The primary outcome was the change in the mean weekly pain intensity from baseline to week 4. Secondary and exploratory outcomes included proportion of participants with ≥30% or ≥50% reduction in pain intensity, change in jaw opening and movement, graded chronic pain scale, jaw functional limitations scale-20-item, depression, anxiety and stress scales-21, Pittsburgh sleep quality index at week 4 and 8, and the pressure pain threshold and surface electromyography at week 4.

RESULTS AND CONCLUSION

The acupuncture group showed significantly reduced pain intensity compared to the sham group at week 4 (-1.49, 95% confidence interval [CI]: -2.32 to -0.65; P < 0.001) and week 8 (-1.23, 95% CI: -2.11 to -0.54; P = 0.001). Acupuncture's effectiveness surpassed sham's at 4 weeks and lasted 8 weeks. Participants in the acupuncture group experienced significantly greater improvements in the 30% and 50% response rate, jaw opening and movement, GCPS, JFLS-20, DASS-21 and PSQI than those in the sham acupuncture group. There were no significant between-group differences in PPT and sEMG. In summary, acupuncture provided marked pain relief and improvement in physical and emotional function for patients with TMD compared with sham acupuncture.

Effects of Selective and Nonselective Beta Blockers on Bone Mineral Density in Mexican Patients with Breast Cancer

Breast cancer (BCa) is related to chronic stress and can reduce the bone mineral density (BMD) through neurochemicals related to beta-adrenergic receptor (ADRB) 1 and 2. Selective beta blockers (sBBs) and nonselective beta blockers (nsBBs) are used to treat systemic arterial hypertension (SAH) and may have osteoprotective effects, as they inhibit ADRBs. To evaluate the effects of sBBs and nsBBs on the BMD of Mexican patients with BCa. A retrospective study was conducted. We included 191 Mexican women with BCa without SAH and with SAH treated with nsBBs, sBBs, and diuretics. BMD was evaluated using a bone density scan (DEX scan). A greater average BMD (p < 0.05) was observed in patients with prior treatment with both nsBBs and sBBs (0.54 ± 0.94 and -0.44 ± 1.22, respectively) compared to patients treated with diuretics or without SAH (-1.73 ± 0.83 and -1.22 ± 0.98, respectively). Regarding the diagnosis of osteoporosis/osteopenia, no cases were observed in patients treated with nsBBs, whereas 5.6% of the patients treated with sBBs presented osteopenia. A total of 23.1% and 10.6% patients managed with diuretics or without treatment presented with osteoporosis and 61.5% and 48% patients managed with loop diuretics and without treatment presented with osteopenia, respectively (p < 0.05). Treatment with nsBBs is a promising option for the prevention and management of osteoporosis/osteopenia in Mexican patients with BCa; however, further prospective studies are needed.

Genetic influence on treatment outcomes in patients with pain-related temporomandibular disorders

BACKGROUND

Single nucleotide polymorphisms (SNPs) may influence pain susceptibility and impact treatment response in pain-related temporomandibular disorders (TMDp).

OBJECTIVE

Explore the role of COMT (rs4646310, rs6269, rs4818, rs4680) and OPRM1 (rs1799971) genotypes in regulating treatment response.

METHODS

Sixty TMDp patients (55 females and 5 males), diagnosed with the Diagnostic Criteria for TMD (DC/TMD), underwent standardised treatment (information and education, home physical therapy, occlusal splint) for 6 months. Treatment outcomes included: pain intensity, pain-free mouth opening, jaw functional limitation, depression, and anxiety. Genotyping for COMT and OPRM1 SNPs was performed using DNA from buccal mucosa swabs and TaqMan assays. Statistical analysis was carried out to compare the changes in treatment outcomes and the influence of genotypes on treatment response.

RESULTS

Significantly less pain reduction was observed in minor allele carriers of rs4646310, and rs4680 compared to dominant homozygous (p < .025). Minor allele carriers of rs1799971 and rs4646310 demonstrated worsening in pain-free mouth opening while dominant homozygous exhibited improvement (p < .025). Significantly less anxiety reduction was observed in minor allele carriers of rs4646310 compared to dominant homozygous (p = .003). Of the all variables assessed in the regression model, carrying a minor allele of rs1799971 predicted a poorer treatment response considering pain-free mouth opening while carrying a minor allele of rs4646310 predicted less pain and less anxiety reduction.

CONCLUSION

Our findings indicate that certain SNP variants of the COMT and OPRM1 genes were associated with poorer treatment response and may therefore play a significant role in the classification of TMDp patients. Also, assessment of patient genotype could potentially aid in predicting treatment response.

Physical therapy in addition to occlusal splint in myogenic temporomandibular disorders: A randomised controlled trial

BACKGROUND

Myogenic temporomandibular disorders (M-TMD) commonly involve occlusal splint (OS) therapy and musculoskeletal physiotherapy (MPT).

OBJECTIVES

To compare the effects of combining OS with MPT and education (EG) against OS and education (CG), in chronic M-TMD patients.

METHODS

In this double-blind randomised controlled trial, 62 participants were assigned to either EG or CG. The primary outcomes, pain levels at rest (VAS rest), maximum oral opening (VAS open) and during chewing (VAS chew), were measured by Visual Analogue Scale (VAS) in cm. The secondary outcome was the range of motion (ROM) for maximum oral opening. Both interventions lasted 3 months, with outcomes assessed at baseline (T0), post-treatment (T1) and 3 months post-treatment (T2).

RESULTS

Intention-to-treat analysis revealed significant improvements favouring EG (VAS rest = -1.50 cm [CI95%: -2.67, -0.32], p = .04; VAS open = -2.00 cm [CI95%: -3.23, -0.75], p < .01; VAS chew = -1.71 cm [CI95%: -2.90, -0.52], p = .01; ROM = 4.61 [CI95%: 0.93, 8.30], p = .04). Additionally, VAS measures were influenced by follow-up times (VAS rest = -0.73 cm [CI95%: -1.30, -0.17], p = 0.03; VAS open = -0.97 cm [CI95%: -1.57, -0.37], p < .01; VAS chew = -1.15 cm [CI95%: -1.73, -0.58], p < .01). At T1, EG demonstrated higher number of responders compared to CG for VAS open (χ2(1) = 4.39, p = .04) and VAS chew (χ2(1) = 11.58, p < .01).

CONCLUSION

Adding MPT to education and OS yields better outcomes in terms of pain reduction and ROM improvement, in chronic M-TMD.

TRIAL REGISTRATION NUMBER

NCT03726060.

Synthesis of temporomandibular disorders management intervention outcomes for development of core outcome sets: A systematic review

INTRODUCTION

The selection of appropriate outcomes in clinical trials and systematic reviews is a crucial factor in determining the results that are useful, reliable, and relevant for both patients and healthcare professionals. Clinicians and researchers have been encouraged to develop and apply core outcome sets (COS) to minimise the discrepancy between studies.

AIM

This systematic review is the first phase of the COS development project for clinical trials in temporomandibular disorders (COS-TMD). It aims to identify and synthesise the outcomes used in the randomised controlled trials (RCT) that evaluated the effectiveness of interventions used in TMD management.

MATERIALS AND METHODS

An electronic search was performed in several databases: MEDLINE (via PubMed), Scopus, Web of Science, Cochrane Library and EMBASE. The eligibility criteria comprised RCT that applied any intervention to treat temporomandibular joint disorders or masticatory muscle disorders. The identified outcomes were categorised according to domains of the Initiative on Methods, Measurement and Pain Assessment in Clinical Trials (IMMPACT).

RESULTS

The electronic search resulted in 1606 studies. After removing duplicates and applying the eligibility criteria, 106 RCT were included. A total of 43 studies evaluated masticatory muscle disorders, 27 evaluated temporomandibular joint disorders, and 36 analysed mixed TMD.

CONCLUSIONS

The evaluation showed significant variability in the types of outcomes and their measurement instruments. In addition, some domains such as physical and emotional functioning, participant ratings of global improvement and adverse events have been neglected when determining the effectiveness of treatments for TMD.

Analysis of the Use of Sample Size and Effect Size Calculations in a Temporomandibular Disorders Randomised Controlled Trial-Short Narrative Review

BACKGROUND/OBJECTIVES

Temporomandibular disorder (TMD) is the term used to describe a pathology (dysfunction and pain) in the masticatory muscles and temporomandibular joint (TMJ). There is an apparent upward trend in the publication of dental research and a need to continually improve the quality of research. Therefore, this study was conducted to analyse the use of sample size and effect size calculations in a TMD randomised controlled trial.

METHODS

The period was restricted to the full 5 years, i.e., papers published in 2019, 2020, 2021, 2022, and 2023. The filter article type-"Randomized Controlled Trial" was used. The studies were graded on a two-level scale: 0-1. In the case of 1, sample size (SS) and effect size (ES) were calculated.

RESULTS

In the entire study sample, SS was used in 58% of studies, while ES was used in 15% of studies.

CONCLUSIONS

Quality should improve as research increases. One factor that influences quality is the level of statistics. SS and ES calculations provide a basis for understanding the results obtained by the authors. Access to formulas, online calculators and software facilitates these analyses. High-quality trials provide a solid foundation for medical progress, fostering the development of personalized therapies that provide more precise and effective treatment and increase patients' chances of recovery. Improving the quality of TMD research, and medical research in general, helps to increase public confidence in medical advances and raises the standard of patient care.

Nociceptive, neuropathic, or nociplastic low back pain? The low back pain phenotyping (BACPAP) consortium's international and multidisciplinary consensus recommendations

The potential to classify low back pain as being characterised by dominant nociceptive, neuropathic, or nociplastic mechanisms is a clinically relevant issue. Preliminary evidence suggests that these low back pain phenotypes might respond differently to treatments; however, more research must be done before making specific recommendations. Accordingly, the low back pain phenotyping (BACPAP) consortium was established as a group of 36 clinicians and researchers from 13 countries (five continents) and 29 institutions, to apply a modified Nominal Group Technique methodology to develop international and multidisciplinary consensus recommendations to provide guidance for identifying the dominant pain phenotype in patients with low back pain, and potentially adapt pain management strategies. The BACPAP consortium's recommendations are also intended to provide direction for future clinical research by building on the established clinical criteria for neuropathic and nociplastic pain. The BACPAP consortium's consensus recommendations are a necessary early step in the process to determine if personalised pain medicine based on pain phenotypes is feasible for low back pain management. Therefore, these recommendations are not ready to be implemented in clinical practice until additional evidence is generated that is specific to these low back pain phenotypes.

Effect of propranolol on temporomandibular joint pain in repeatedly stressed rats

Stress substantially increases the risk of developing painful temporomandibular disorders (TMDs) by influencing the release of endogenous catecholamines. Propranolol, an antagonist of β-adrenergic receptors, has shown potential in alleviating TMD-associated pain, particularly when the level of catecholamines is elevated. The aim of this study was to explore whether intra-articular propranolol administration is effective in diminishing temporomandibular joint (TMJ) pain during repeated stress situations. Additionally, we investigated the effect of repeated stress on the expression of genes encoding β-adrenoceptors in the trigeminal ganglion. In the present study, rats were exposed to a stress protocol induced by sound, then to the administration of formalin in the TMJ (to elicit a nociceptive response), followed immediately afterward by different doses of propranolol, after which the analgesic response to propranolol was evaluated. We also assessed the levels of beta-1 and beta-2 adrenergic receptor mRNAs (Adrb1 and Adrb2, respectively) using reverse transcription-quantitative PCR (RT-qPCR). Our findings revealed that propranolol administration reduces formalin-induced TMJ nociception more effectively in stressed rats than in non-stressed rats. Furthermore, repeated stress decreases the expression of the Adrb2 gene within the trigeminal ganglion. The findings of this study are noteworthy as they suggest that individuals with a chronic stress history might find potential benefits from β-blockers in TMD treatment.

Diagnostic Accuracy of a Temporomandibular Disorder Pain Screener in Patients Seeking Endodontic Treatment for Tooth Pain

INTRODUCTION

This study assessed the accuracy of a TMD Pain Screener questionnaire in identifying patients with temporomandibular disorder (TMD) pain among those seeking endodontic treatment for tooth pain. It also investigated whether the screener accuracy could be improved by adding questions regarding putative predictors of TMD status.

METHODS

One hundred patients seeking endodontic treatment for tooth pain were enrolled. Participants completed the 6-question TMD Pain Screener before treatment. A board-certified orofacial pain specialist/endodontic resident conducted endodontic and TMD examinations using validated Diagnostic Criteria for TMD (DC/TMD). The sensitivity (Se), specificity (Sp), and positive/negative predictive values (PPVs/NPVs) were calculated for the 6-question and 3-question versions of the TMD Pain Screener. Logistic regression and receiver operating characteristic curve (AUROC) analyses were performed to determine the screening accuracy.

RESULTS

At the screening threshold of ≥3, TMD Pain Screener's sensitivity was 0.85, specificity 0.52, PPV 0.68, and NPV 0.75 for the 6-question version and 0.64, 0.65, 0.69, and 0.61, respectively, for the 3-question version. The AUROC was 0.71 (95% CL: 0.61, 0.82) and 0.60 (95% CL: 0.48, 0.71) for full and short versions, respectively. Adding a rating of current pain intensity of the chief complaint to the screener improved the AUROC to 0.81 (95% CL: 0.72, 0.89) and 0.77 (95% CL: 0.67, 0.86) for full and short versions, respectively, signifying useful overall accuracy.

CONCLUSIONS

The 6-question TMD Pain Screener, combined with the patient's rating of current pain intensity of the chief complaint, could be recommended for use in endodontic patients with tooth pain for detecting painful TMD.

Pharmacological Treatments of Temporomandibular Disorders: A Systematic Review Including a Network Meta-Analysis

OBJECTIVE

Temporomandibular disorders (TMD) comprise a cluster of conditions with a wide range of etiological factors that causes pain and discomfort in the masticatory muscles (TMD-M) and temporomandibular joints (TMD-J). More than 50% of the patients with TMD report regular usage of drugs. However, there is still no consensus, nor is there any evidence-based support for clinicians when choosing between different drugs. Therefore, this systematic review, including a network meta-analysis (NMA), aimed to evaluate the scientific evidence and discuss the pharmacological treatment options available to treat painful TMD.

METHOD

An electronic search was undertaken to identify randomized controlled trials (RCTs) investigating pharmacological treatments for TMD-M and/or TMD-J, published until 6 April 2023. Since only 11 articles could be used for an NMA regarding TMD-M, a narrative synthesis was also performed for all 40 included RCTs. The quality of evidence was rated according to Cochrane's tool for assessing risk of bias, while the certainty of evidence was rated according to Grading of Recommendations Assessment, Development and Evaluation (GRADE).

RESULTS

When it comes to TMD-M, evidence arises for wet needling therapies with BTX-A, granisetron, and PRP as well as muscle relaxants. For TMD-J, evidence points toward pharmacological treatment approaches including non-steroidal antiinflammatory drugs (NSAIDs) and glucocorticosteriods (for inflammatory conditions) as well as hyaluronic acid and dextrose.

CONCLUSIONS

The evidence clearly indicates that the pharmacological treatment approaches differ between TMD-M and TMD-J. Therefore, it is of great importance to first try to uncover each patient's individual and multifactorial etiology and then employ a multifaceted treatment strategy, including pharmacological treatment approaches.

Repurposing Antihypertensive and Statin Medications for Spinal Pain: A Mendelian Randomization Study

STUDY DESIGN

Mendelian randomization (MR) study.

OBJECTIVE

To examine whether antihypertensive medications (beta-blockers, calcium channel blockers, and angiotensin-converting enzyme inhibitors) and statins can be repurposed to prevent or treat spinal pain (back or neck pain).

SUMMARY OF BACKGROUND DATA

Observational studies and a recent MR study have found associations between elevated blood pressure and a greater risk of back pain. Observational studies have found associations between hyperlipidemia and statin use and greater risk of back pain. No prior MR studies have examined the effects of antihypertensives or statins on spinal pain.

MATERIALS AND METHODS

This was a two-sample MR study using publicly available summary statistics from large-scale genome-wide association studies (GWAS). Sample sizes in exposure GWASs were n=757,601 (systolic blood pressure) and n=173,082 (low-density lipoprotein cholesterol), and n=1,028,947 for the outcome GWAS of spinal pain defined as health care seeking for any spinal pain-related diagnosis. Genes and cis-acting variants were identified as proxies for the drug targets of interest. MR analyses used inverse-variance weighted meta-analysis. The threshold for statistical significance after correction for multiple testing was P <0.0125.

RESULTS

No statistically significant associations of these medications with spinal pain were found. However, findings were suggestive of a protective effect of beta-blockers on spinal pain risk (odds ratio [OR] 0.84, 95% confidence interval [CI] 0.72-0.98; P =0.03), and calcium channel blockers on greater spinal pain risk (OR 1.12, 95% CI 1.02-1.24; P =0.02).

CONCLUSIONS

A protective effect of beta-blockers on spinal pain was suggested in the current study, consistent with findings from observational studies of various other pain phenotypes. The detrimental effect of calcium channel blockers on spinal pain suggested in the current study must be interpreted in the context of conflicting directions of effect on nonspinal pain phenotypes in other observational studies.This Mendelian randomization study examined whether antihypertensive medications (beta-blockers, calcium channel blockers, and angiotensin-converting enzyme inhibitors) and statins can be repurposed to prevent or treat spinal.This was a two-sample MR study using publicly available summary statistics from large-scale genome-wide association studies ranging size from 173,082 to 1,028,947 adults.While no statistically significant associations were found, a protective effect of beta-blockers on spinal pain was suggested (odds ratio [OR] 0.84, 95% confidence interval [CI] 0.72 to 0.98; p= 0.03), as was a detrimental effect of calcium channel blockers on spinal pain (OR 1.12, 95% CI 1.02 to 1.24; p= 0.02).

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.

Stress circuitry: mechanisms behind nervous and immune system communication that influence behavior

Inflammatory processes are increased by stress and contribute to the pathology of mood disorders. Stress is thought to primarily induce inflammation through peripheral and central noradrenergic neurotransmission. In healthy individuals, these pro-inflammatory effects are countered by glucocorticoid signaling, which is also activated by stress. In chronically stressed individuals, the anti-inflammatory effects of glucocorticoids are impaired, allowing pro-inflammatory effects to go unchecked. Mechanisms underlying this glucocorticoid resistance are well understood, but the precise circuits and molecular mechanisms by which stress increases inflammation are not as well known. In this narrative review, we summarize the mechanisms by which chronic stress increases inflammation and contributes to the onset and development of stress-related mood disorders. We focus on the neural substrates and molecular mechanisms, especially those regulated by noradrenergic signaling, that increase inflammatory processes in stressed individuals. We also discuss key knowledge gaps in our understanding of the communication between nervous and immune systems during stress and considerations for future therapeutic strategies. Here we highlight the mechanisms by which noradrenergic signaling contributes to inflammatory processes during stress and how this inflammation can contribute to the pathology of stress-related mood disorders. Understanding the mechanisms underlying crosstalk between the nervous and immune systems may lead to novel therapeutic strategies for mood disorders and/or provide important considerations for treating immune-related diseases in individuals suffering from stress-related disorders.

Yoga and massage are associated with small experimental placebo effects in chronic orofacial pain

BACKGROUND

Complementary and Integrative Health Approaches (CIHA), including but not limited to, natural products and Mind and Body Practices (MBPs), are promising non-pharmacological adjuvants to the arsenal of pain management therapeutics. We aim to establish possible relationships between use of CIHA and the capacity of descending pain modulatory system in the form of occurrence and magnitude of placebo effects in a laboratory setting.

METHODS

This cross-sectional study investigated the relationship between self-reported use of CIHA, pain disability, and experimentally induced placebo hypoalgesia in chronic pain participants suffering from Temporomandibular Disorders (TMD). In the 361 enrolled TMD participants, placebo hypoalgesia was measured using a well-established paradigm with verbal suggestions and conditioning cues paired with distinct heat painful stimulations. Pain disability was measured with the Graded Chronic Pain Scale, and use of CIHA were recorded with a checklist as part of the medical history.

RESULTS

Use of physically oriented MBPs (e.g., yoga and massage) was associated with reduced placebo effects (F1,2110.44  = 23.15, p < 0.001, Cohen's d = 0.171). Further, linear regressions indicated that greater number of physically oriented MBPs predicted smaller placebo effects (β = -0.17, p = 0.002), and less likelihood of being a placebo responder (OR = 0.70, p = 0.004). Use of psychologically oriented MBPs and natural product were not associated with placebo effects magnitude and responsiveness.

CONCLUSIONS

Our findings suggest that use of physically oriented CIHA was associated with experimental placebo effects possibly through an optimized capability to recognize distinct somatosensorial stimulations. Future research is needed to understand the mechanisms underlying placebo-induced pain modulation in CIHA users.

SIGNIFICANCE

Chronic pain participants who use physically oriented mind-body practices, such as yoga and massage, demonstrated attenuated experimentally induced placebo hypoalgesia in comparison with those who do not use them. This finding disentangled the relationship between use of complementary and integrative approaches and placebo effects, providing the potential therapeutic perspective of endogenous pain modulation in chronic pain management.

Effect of sound-induced repeated stress on the development of pain and inflammation in the temporomandibular joint of female and male rats

Temporomandibular disorder (TMD) is a common painful condition of the temporomandibular joint (TMJ) and associated structures. Stress is a significant risk factor for developing this painful condition that predominantly affects women. This study aimed to test the hypothesis that stress increases the risk of developing TMJ pain by facilitating inflammatory mechanisms in female and male rats. To test this hypothesis, we evaluated TMJ carrageenan-induced expression of pro-inflammatory cytokines and migration of inflammatory cells and TMJ formalin-induced nociception in female and male rats submitted to a repeated stress protocol induced by sound. We found that sound-induced repeated stress facilitates TMJ inflammation and contributes to TMJ nociception development equally in females and males. We conclude that stress is a risk factor for developing painful TMJ conditions in males and females, at least in part, by favoring the inflammatory process similarly in both sexes.

Temporomandibular Joint Disorder Comorbidities

Comorbidity is a distinct additional condition that either existed or exists during the clinical course of a patient afflicted by the condition/entity in question. The clinician attempting to manage temporomandibular joint disorder (TMD) and TMD pain must realize that recognition and management of the comorbidities are essential to the successful management of the same with optimal pain control. When TMD presents with multiple comorbidities, the task for the clinician becomes more complex. It is the hope of the authors that this condensed version of TMD-associated comorbidities acts as a primer for understanding the significance of the same in pain management.

Biopsychosocial influence on shoulder pain: results from a randomized preclinical trial of exercise-induced muscle injury

ABSTRACT

Prior cohort studies validated that a subgroup defined by a specific COMT genotype and pain catastrophizing is at increased risk for heightened responses to exercise-induced or surgically induced shoulder pain. In this clinical trial, we used our preclinical model of exercise-induced muscle injury and pain to test the efficacy of interventions matched to characteristics of this high-risk subgroup (ie, personalized medicine approach). Potential participants provided informed consent to be screened for eligibility based on subgroup membership and then, as appropriate, were enrolled into the trial. Participants (n = 261) were randomized to 1 of 4 intervention groups comprised of pharmaceutical (propranolol or placebo) and informational (general education or psychologic intervention) combinations. After muscle injury was induced, participants received randomly assigned treatment and were followed for the primary outcome of shoulder pain intensity recovery over 4 consecutive days. Recovery rates were 56.4% (placebo and psychologic intervention), 55.4% (placebo and general education), 62.9% (propranolol and psychologic intervention), and 56.1% (propranolol and general education). No statistical differences were found between intervention groups in the primary analyses. Additional analyses found no differences between these intervention groups when shoulder pain duration was an outcome, and no differential treatment responses were detected based on sex, race, or level of pain catastrophizing. This trial indicates that these treatments were not efficacious for this high-risk subgroup when shoulder pain was induced by exercise-induced muscle injury. Accordingly, this phenotype should only be used for prognostic purposes until additional trials are completed in clinical populations.

Pain Management and Rehabilitation for Central Sensitization in Temporomandibular Disorders: A Comprehensive Review

Temporomandibular disorders (TMD) are a group of musculoskeletal diseases affecting masticatory muscles and temporomandibular joints (TMJ). In this context, the chronic TMD could be considered as a condition with chronic primary orofacial pain, presenting as myofascial TMD pain or TMJ arthralgia. In this context, myogenous TMD may present overlapping features with other disorders, such as fibromyalgia and primary headaches, characterized by chronic primary pain related to dysfunction of the central nervous system (CNS), probably through the central sensitization. This phenomenon could be defined as an amplified response of the CNS to sensory stimuli and peripheral nociceptive, characterized by hyperexcitability in the dorsal horn neurons in the spinal cord, which ascend through the spinothalamic tract. The main objectives of the management of TMD patients are: decreasing pain, increasing TMJ function, and reducing the reflex masticatory muscle spasm/pain. The first-line treatments are physical therapy, pharmacological drugs, occlusal splints, laser therapy, extracorporeal shockwave therapy, transcutaneous electrical nerve stimulation, and oxygen-ozone therapy. Although all these therapeutic approaches were shown to have a positive impact on the central sensitization of TMD pain, there is still no agreement on this topic in the scientific literature. Thus, in this comprehensive review, we aimed at evaluating the evidence on pain management and rehabilitation for the central sensitization in TMD patients.

A graph-embedded topic model enables characterization of diverse pain phenotypes among UK biobank individuals

Large biobank repositories of clinical conditions and medications data open opportunities to investigate the phenotypic disease network. We present a graph embedded topic model (GETM). We integrate existing biomedical knowledge graph information in the form of pre-trained graph embedding into the embedded topic model. Via a variational autoencoder framework, we infer patient phenotypic mixture by modeling multi-modal discrete patient medical records. We applied GETM to UK Biobank (UKB) self-reported clinical phenotype data, which contains 443 self-reported medical conditions and 802 medications for 457,461 individuals. Compared to existing methods, GETM demonstrates good imputation performance. With a more focused application on characterizing pain phenotypes, we observe that GETM-inferred phenotypes not only accurately predict the status of chronic musculoskeletal (CMK) pain but also reveal known pain-related topics. Intriguingly, medications and conditions in the cardiovascular category are enriched among the most predictive topics of chronic pain.

•

Interpretable deep learning to integrate knowledge graphs and patient data

•

Modeling phenotypes from self-reports of 457,461 individuals from the UK Biobank

•

Predicting and characterizing chronic pain phenotypes using latent phenotypes

•

Potential link between cardiovascular conditions or medications and chronic pain

Proposing a "Brain Health Checkup (BHC)" as a Global Potential "Standard of Care" to Overcome Reward Dysregulation in Primary Care Medicine: Coupling Genetic Risk Testing and Induction of "Dopamine Homeostasis"

In 2021, over 100,000 people died prematurely from opioid overdoses. Neuropsychiatric and cognitive impairments are underreported comorbidities of reward dysregulation due to genetic antecedents and epigenetic insults. Recent genome-wide association studies involving millions of subjects revealed frequent comorbidity with substance use disorder (SUD) in a sizeable meta-analysis of depression. It found significant associations with the expression of NEGR1 in the hypothalamus and DRD2 in the nucleus accumbens, among others. However, despite the rise in SUD and neuropsychiatric illness, there are currently no standard objective brain assessments being performed on a routine basis. The rationale for encouraging a standard objective Brain Health Check (BHC) is to have extensive data available to treat clinical syndromes in psychiatric patients. The BHC would consist of a group of reliable, accurate, cost-effective, objective assessments involving the following domains: Memory, Attention, Neuropsychiatry, and Neurological Imaging. Utilizing primarily PUBMED, over 36 years of virtually all the computerized and written-based assessments of Memory, Attention, Psychiatric, and Neurological imaging were reviewed, and the following assessments are recommended for use in the BHC: Central Nervous System Vital Signs (Memory), Test of Variables of Attention (Attention), Millon Clinical Multiaxial Inventory III (Neuropsychiatric), and Quantitative Electroencephalogram/P300/Evoked Potential (Neurological Imaging). Finally, we suggest continuing research into incorporating a new standard BHC coupled with qEEG/P300/Evoked Potentials and genetically guided precision induction of "dopamine homeostasis" to diagnose and treat reward dysregulation to prevent the consequences of dopamine dysregulation from being epigenetically passed on to generations of our children.

Clinical, psychological, and sensory characteristics associated with headache attributed to temporomandibular disorder in people with chronic myogenous temporomandibular disorder and primary headaches

Background

Headache attributed to Temporomandibular Disorder (HATMD) is a secondary headache that may have features resulting in diagnostic overlap with primary headaches, namely, tension-type (TTH) or migraine. This cross-sectional study of people with both chronic myogenous TMD and primary headaches evaluated characteristics associated with HATMD.

Methods

From a clinical trial of adults, baseline data were used from a subset with diagnoses of both TMD myalgia according to the Diagnostic Criteria for TMD (DC/TMD) and TTH or migraine according to the International Classification of Headache Disorders, 3rd edition. HATMD was classified based on the DC/TMD. Questionnaires and examinations evaluated 42 characteristics of facial pain, headache, general health, psychological distress, and experimental pain sensitivity. Univariate regression models quantified the associations of each characteristic with HATMD (present versus absent), headache type (TTH versus migraine), and their interaction in a factorial design. Multivariable lasso regression identified the most important predictors of HATMD.

Results

Of 185 participants, 114 (61.6%) had HATMD, while the numbers with TTH (n = 98, 53.0%) and migraine (n = 87, 47.0%) were similar. HATMD was more likely among migraineurs (61/87 = 70.1%) than participants with TTH (53/98 = 54.1%; odds ratio = 2.0; 95%CL = 1.1, 3.7). In univariate analyses, characteristics associated with HATMD included pain-free jaw opening and examination-evoked pain in masticatory muscles and temporomandibular joints (TMJ) as well as frequency and impact of headache, but not frequency or impact of facial pain. Lowered blood pressure but not psychological or sensory characteristics was associated with HATMD. Multiple characteristics of facial pain, headache, general health, and psychological distress differed between TTH or migraine groups. Few interactions were observed, demonstrating that most characteristics’ associations with HATMD were consistent in TTH and migraine groups. The lasso model identified headache frequency and examination-evoked muscle pain as the most important predictors of HATMD.

Conclusions

HATMD is highly prevalent among patients with chronic myogenous TMD and headaches and often presents as migraine. In contrast to primary headaches, HATMD is associated with higher headache frequency and examination-evoked masticatory muscle pain, but with surprisingly few measures of facial pain, general health, and psychological distress. A better understanding of HATMD is necessary for developing targeted strategies for its management.

Trial identification and registration

SOPPRANO; NCT02437383. Registered May 7, 2015.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10194-021-01255-1.

Effect of comorbid migraine on propranolol efficacy for painful TMD in a randomized controlled trial

Introduction

The migraine-preventive drug propranolol is efficacious in reducing pain from temporomandibular disorder, suggesting potential modifying or mediating effects of comorbid migraine.

Methods

In this randomized controlled trial, myofascial temporomandibular disorder patients were treated with propranolol or placebo for 9 weeks. The primary endpoint was change in a facial pain index derived from daily symptom diaries. Linear and logistic regression models tested for a migraine × treatment-group interaction in reducing facial pain index. Counterfactual models explored changes in headache impact and heart rate as mediators of propranolol's efficacy.

Results

Propranolol's efficacy in reducing facial pain index was greater among the 104 migraineurs than the 95 non-migraineurs: For example, for the binary ≥ 30% reduction in facial pain index, odds ratios were 3.3 (95% confidence limits: 1.4, 8.1) versus 1.3 (0.5, 3.2), respectively, although the interaction was statistically non-significant (p = 0.139). Cumulative response curves confirmed greater efficacy for migraineurs than non-migraineurs (differences in area under the curve 26% and 6%, respectively; p = 0.081). While 9% of the treatment effect was mediated by reduced headache impact, 46% was mediated by reduced heart rate.

Conclusions

Propranolol was more efficacious in reducing temporomandibular disorder pain among migraineurs than non-migraineurs, with more of the effect mediated by reduced heart rate than by reduced headache impact.

Study identification and registration

SOPPRANO; NCT02437383; https://clinicaltrials.gov/ct2/show/NCT02437383

Multitargeting the sleep-pain interaction with pharmacological approaches: A narrative review with suggestions on new avenues of investigation

The multimorbidity formed by sleep disturbances and pain conditions is highly prevalent and has a significant impact in global health and in the socioeconomic system. Although different approaches have been directed toward its management, evidence regarding an optimal treatment is lacking, and pharmacological options are often preferred. Health professionals (e.g., pain and sleep clinicians) tend to focus on their respective expertise, targeting a single symptom with a single drug. This may increase polypharmacy and the risk of drug interactions, adverse events, and mortality. Hence, the use of medications that can directly or indirectly improve sleep, pain, and other possible accompanying conditions without exacerbating them becomes especially relevant. The objectives of this comprehensive review are to: a) describe the beneficial or deleterious effects that some commonly used medications to manage pain have on sleep and sleep disorders; and b) describe the beneficial or deleterious effects that frequently prescribed medications for sleep may have on pain. Moreover, medications targeting some specific sleep-pain interactions will be suggested and future directions for improving sleep and alleviating pain of these patients will be provided with clinical and research perspectives.

Preliminary evidence for conserved transcriptional response to adversity in adults with temporomandibular disorder

Temporomandibular disorder (TMD) is one of the most common orofacial pain conditions. Alteration in immune functioning is one promising biological mechanism underlying pain in TMD. However, there is a gap in the understanding of molecular bases contributing to altered immune functioning in these patients.

OBJECTIVES

In the current study, we investigated whether individuals with TMD would exhibit differential activity of 3 specific transcription factors involved in inflammatory (nuclear factor-kappa B, NF-kB), antiviral (interferon-regulatory factors, IRF), and sympathetic (cAMP response element-binding protein, CREB) processes using a promoter-based bioinformatics analysis, which is characterized as the "Conserved Transcriptional Response to Adversity."

METHODS

Adults with TMD (n = 19) and without (n = 17) underwent a standardized clinical examination for TMD. A blood sample was collected for genome-wide transcriptional RNA profiling. Bioinformatic analyses tested for differential prevalence of proinflammatory and antiviral transcription factor activity in core promoter sequences from all genes showing >1.2-fold differential expression in TMD vs controls.

RESULTS

Promoter-based bioinformatic analyses of genome-wide transcriptome profiles confirmed upregulation of genes bearing response elements for proinflammatory transcription factor (NF-kB, P = 0.002) and downregulation of genes with response elements for IRF (P = 0.037) in patients with TMD relative to controls. Results also indicated upregulated activity of CREB in patients with TMD (P = 0.08), consistent with increased activity of the sympathetic nervous system.

CONCLUSION

These results provide initial support that the regulation of immune pathways is altered in individuals with TMD. A shift of transcriptional resources to a proinflammatory state may be driven by psychosocial stress and contributes to symptoms associated with TMD.

COMT Genotype and Efficacy of Propranolol for TMD Pain: A Randomized Trial

Propranolol is a nonselective β-adrenergic receptor antagonist that is efficacious in reducing facial pain. There is evidence that its analgesic efficacy might be modified by variants of the catechol-O-methyltransferase (COMT) gene. We tested the hypothesis in a subset of 143 non-Hispanic Whites from a randomized controlled trial of patients with painful temporomandibular disorder (TMD). Patients were genotyped for rs4680, a single nucleotide polymorphism of COMT, and randomly allocated to either propranolol 60 mg twice daily or placebo. During the 9-wk follow-up period, patients recorded daily ratings of facial pain intensity and duration; the product was computed as an index of facial pain. Postbaseline change in the index at week 9 (the primary endpoint) was analyzed as a continuous variable and dichotomized at thresholds of ≥30% and ≥50% reduction. Mixed models for repeated measures tested for the genotype × treatment group interaction and estimated means, odds ratios (ORs), and 95% confidence limits (95% CLs) of efficacy within COMT genotypes assuming an additive genetic model. In secondary analysis, the cumulative response curves were plotted for dichotomized reductions ranging from ≥20% to ≥70%, and genotype differences in area under the curve percentages (%AUC) were calculated to signify efficacy. Mean index reduction did not differ significantly (P = 0.277) according to genotype, whereas the dichotomized ≥30% reduction revealed greater efficacy among G:G homozygotes (OR = 10.9, 95%CL = 2.4, 50.7) than among A:A homozygotes (OR = 0.8, 95%CL = 0.2, 3.2) with statistically significant interaction (P = 0.035). Cumulative response curves confirmed greater (P = 0.003) efficacy for G:G homozygotes (%AUC difference = 43.7, 95%CL = 15.4, 72.1) than for A:A homozygotes (%AUC difference = 6.5, 95%CL = -30.2, 43.2). The observed antagonistic effect of the A allele on propranolol’s efficacy was opposite the synergistic effect hypothesized a priori. This unexpected result highlights the need for better knowledge of COMT’s role in pain pathogenesis if the gene is to be used for precision-medicine treatment of TMD (ClinicalTrials.gov NCT02437383).

Effect of Treatment Expectation on Placebo Response and Analgesic Efficacy: A Secondary Aim in a Randomized Clinical Trial

This randomized clinical trial assessed the effect of patients’ treatment expectations on the efficacy of propranolol vs placebo among patients with temporomandibular disorder–associated myalgia.