Differences in suprathreshold heat pain responses and self-reported sleep quality between patients with temporomandibular joint disorder and healthy controls

Differential pain perception among females with or without nonspecific chronic low back pain and comorbid insomnia: a quantitative sensory testing analysis

ABSTRACT

Sleep disturbance is a prevalent condition in individuals with chronic low back pain (CLBP). Despite a strong association between the 2 conditions, the potential mechanisms underlying the role of sleep disturbance in CLBP remain unclear. This case-control study aimed to examine pain perception among females with or without nonspecific CLBP and comorbid insomnia. One hundred females were recruited (mean age: 34.3 ± 11.4 years), with 25 individuals with concomitant CLBP and insomnia (CLBP+I), 25 with CLBP (CLBP+), 25 with insomnia (Insomnia+), and 25 healthy controls. All participants completed self-report questionnaires and quantitative sensory testing (QST). Our study found that CLBP+I exhibited lower mechanical pain and pressure pain thresholds (PPT) in both painful and nonpainful areas and impaired conditioned pain modulation (CPM) as compared to healthy controls. Similar findings were found in PPT at the back and CPM when compared to CLBP+. However, no significant differences were noted in thermal pain thresholds and temporal summation of pain across the 4 groups. Furthermore, CLBP+I and Insomnia+ displayed higher levels of functional disability, maladaptive beliefs, and negative mood than CLBP+ or healthy controls. There were significant increases in pain sensitivity to pressure stimuli, decreases in descending pain inhibitory effects, and higher levels of maladaptive psychological status in CLBP+I compared to CLBP+. These findings underscore the importance of incorporating sleep assessments as a routine practice in treating CLBP cases. Future studies are warranted to validate our findings in males, establish the diagnostic and prognostic value of QST, and probe the neurophysiological mechanisms in comorbid conditions.

The Association Between Insomnia and Temporomandibular Disorders in Orthodontic Patients

Objective

This cross-sectional study aimed to investigate the association between insomnia and the presence of temporomandibular disorders (TMD) and its subtypes in orthodontic patients.

Methods

A total of 648 adult orthodontic patients (158 males and 490 females, median age 26) were included and completed a questionnaire containing sociodemographic information, insomnia severity index (ISI), the five major temporomandibular disorder symptoms (5Ts) checklist, and self-reported sleep bruxism. Presence of insomnia and TMD of the included patients was determined according to the diagnostic criteria, and statistical analyses were conducted as appropriate to compare ISI-related scores between TMD and non-TMD participants. Further, multivariable regressions were performed to detect the potential correlation between insomnia and TMD in orthodontic patients.

Results

Orthodontic patients with TMD scored significantly higher in both the individual items and the total sum of ISI than those without TMD. More patients were bothered by insomnia in the TMD group than the non-TMD counterparts (26.6% vs 16.7%, p=0.003). After adjusting for confounding variables, insomnia was found to be significantly correlated with TMD in orthodontic patients (OR=1.677, 95% CI 1.128, 2.511). Subgroup analysis of TMD subtypes showed a significant positive association of insomnia with pain-related TMD (OR=2.007, 95% CI 1.331, 3.015).

Conclusion

Insomnia was associated with a higher prevalence of pain-related TMD rather than intra-articular TMD in orthodontic patients.

The Effect of Superficial Heat-Cold Application on the Sleep Quality of Patients With Restless Leg Syndrome: A Systematic Review and Meta-Analysis

AIM

The present study was conducted to determine the effect of the superficial heat-cold application on the sleep quality of patients with restless leg syndrome.

DESIGN

This study was a systematic review and meta-analysis.

METHODS

In the present study, the electronic databases Scopus, ProQuest, Web of Science, PubMed, SID and Google Scholar were searched from their inception to September 2023. The quality of included studies was evaluated through the Cochrane Collaboration's Risk of Bias Tool, and finally, a meta-analysis was conducted by calculating standardised mean differences (SMDs).

RESULTS

The meta-analysis results revealed that superficial heat-cold application improved sleep quality in patients with RLS (SMD = 0.685, 95% CI: 0.421-0.950). The meta-regression results showed that as the temperature increased, the intervention was more effective in improving sleep quality (β = 0.0182, 95% CI: 0.0096-0.0268, p < 0.05). Moreover, the effectiveness of the intervention in improving the sleep quality of patients with RLS reduced significantly as the duration of intervention in each session (β = -0.031, 95% CI: -0.059 to -0.001, p < 0.05) as well as participants' age increased (β = -0.013, 95% CI: -0.024 to -0.001, p = 0.0259).

PATIENT OR PUBLIC CONTRIBUTION

This research showed that superficial heat-cold application had the capability to improve the sleep quality of patients with restless leg syndrome. In addition, in this study, settings were suggested according to which the maximum effectiveness of the intervention could be achieved.

The Impact of Sleep Disturbances on Endogenous Pain Modulation: A Systematic Review and Meta-Analysis

The bidirectional relationship between sleep and pain problems has been extensively demonstrated but despite all the accumulating evidence, their shared mechanisms are currently not fully understood. This review examined the association between sleep disturbances, defined as a broad array of sleep-related outcomes (eg, poor quality, short duration, insomnia), and endogenous pain modulation (EPM) in healthy and clinical populations. Our search yielded 6,151 references, and 37 studies met the eligibility criteria. Qualitative results showed mixed findings regarding the association between sleep disturbances and temporal summation of pain (TSP) and conditioned pain modulation (CPM), with poor sleep more commonly associated with decreased pain inhibition in both populations. Quantitative results indicated that such associations were not statistically significant, neither in healthy populations when EPM outcomes were assessed for changes pre-/post-sleep intervention (TSP: .31 [95%CI: -.30 to .92]; P = .321; CPM: .40 [95%CI: -.06 to .85] P = .088) nor in clinical populations when such association was assessed via correlation (TSP: -.00 [95%CI: -.22 to .21] P = .970; CPM: .12 [95%CI: -.05 to .29]; P = .181). For studies that reported results by sex, meta-analysis showed that experimental sleep disturbances impaired pain inhibition in females (1.43 [95%CI: .98-1.88]; P < .001) but not in males (-.30 [95%CI: -2.69 to 1.60]; P = .760). Only one study investigating the association between sleep disturbances and offset analgesia was identified, while no studies assessing spatial summation of pain were found. Overall, this review provides a comprehensive overview of the association between sleep disturbances and EPM function, emphasizing the need for further investigation to clarify specific mechanisms and phenotypic subtypes. PERSPECTIVE: This review shines a light on the association between sleep disturbances and endogenous pain modulation function. Qualitatively, we found a frequent association between reduced sleep quality and impaired pain inhibition. However, quantitatively such an association was not corroborated. Sex-specific effects were observed, with females presenting sleep-related impaired pain inhibition but not males.

Enhanced pain facilitation rather than impaired pain inhibition in burning mouth syndrome female patients

Background

Deficient endogenous pain modulation has been implicated in the development and exacerbation of chronic orofacial pain. To date, relatively little is known regarding the function of the endogenous pain modulation in patients with burning mouth syndrome (BMS). This case–control study investigated endogenous pain modulation in women with BMS.

Methods

Conditioned pain modulation (CPM) was assessed upon temporal summation (TSP) of thermal pain. Forty female subjects, 20 BMS patients and 20 age-matched control subjects, were included in a 2 session-protocol. Mechanical and thermal pain thresholds were measured on the forearm and hand. TSP was obtained using repetitive laser-evoked thermal stimuli applied on the non-dominant hand, at an intensity yielding to moderate pain. During TSP, CPM was produced by immersing the contralateral foot in a water bath at painful cold (8 °C) temperature. In control conditions, the foot was immersed in a water bath at not painful (30 °C) temperature.

Results

BMS was not associated with any impairment in thermal as well as mechanical extracephalic pain thresholds. TSP and CPM efficacy were similar in BMS patients and control subjects. However, BMS patients exhibited enhanced extracephalic heat hyperalgesia.

Conclusion

This study reveals that there is no impairment of endogenous pain inhibition mechanisms in BMS patients, but rather an increase in pain facilitation.

Temporal Summation and Aftersensations of Second Pain in Women with Myofascial Temporomandibular Disorder Differ by Presence of Temporomandibular Joint Pain

Purpose

Mechanisms underlying myofascial temporomandibular disorder (mTMD) are poorly understood. One theory is dysfunction in the central mediation of pain, specifically in enhanced facilitatory pain modulation. Because mechanisms leading to central sensitization may differ for joint and muscle pain, this study of mTMD addressed phenotypic heterogeneity by temporomandibular (TM) joint pain in the examination of quantitative sensory testing (QST).

Patients and Methods

The stimulus dependent increase in second pain (temporal summation (TS)) and associated aftersensations (AS) were examined across groups of women with mTMD with TM joint pain and without, and a demographically matched control group.

Results

TS was slightly more evident in mTMD without joint pain vs with (p = 0.035), but AS were most robustly persistent in the group with joint pain vs without (p < 0.002).

Conclusion

While both subgroups demonstrated evidence of central sensitization relative to controls on one of two measures, differences in QST results, if replicated, may point to possible differences in the mechanisms that yield central sensitization. Alternatively, it may represent methodological artifacts that need to be addressed. Therefore, greater consideration should be given to symptom-based phenotypes in studies examining TS and AS.

Evidence for alterations to dynamic quantitative sensory tests in patients with chronic temporomandibular myalgia: a systematic review of observational studies with meta-analysis

BACKGROUND

Conflicting results exist between somatosensory profiles of patients with temporomandibular myalgia (TMDm). The objective of this review was to examine whether adults with TMDm show altered responses to dynamic quantitative sensory tests compared with healthy controls.

METHODS

We searched five electronic databases for studies, excluding those without suitable controls or where TMDm was associated with confounding non-musculoskeletal disorders. Risk of bias was assessed with the SIGN case-control study checklist. Findings were structured around dynamic quantitative sensory tests and their localization. Where possible, we performed meta-analysis with a random inverse variance model to compare patients with TMDm and healthy controls. Statistical heterogeneity was estimated with Chi² test and inconsistency index, I².

RESULTS

We extracted data from 23 studies comprising 1284 adults with chronic TMDm and 2791 healthy controls. Risk of bias was assessed as high for 20 studies. Mechanical temporal summation, the most studied phenomenon (14 studies), is increased in the upper limb of patients with TMDm (SMD = .43; 95% CI: .11 to .75; p = .0001) but not in the jaw area (p = .09) or in the cervical area (p = .29). Very little evidence for altered thermal temporal summation (five studies), conditioned pain modulation (seven studies), exercise-induced hypoalgesia (two studies), placebo analgesia (two studies), stress-induced hypoalgesia (one study) and offset analgesia (one study) was found.

DISCUSSION

A major limitation of this review was the risk of bias of included studies. Future studies would benefit from following methodological guidelines and consideration of confounding factors.

Subjective sleep quality and temporomandibular disorders: Systematic literature review and meta-analysis

STUDY OBJECTIVES

To assess the general subjective sleep quality in individuals with and without TMD, and its distribution among the TMD diagnostic groups.

METHODS

A systematic review search was performed in Pubmed/MEDLINE, Embase, LILACS, Web of Science, SciELO, CINAHL and Cochrane Central as well as in the grey literature. Observational studies published since 1992 which used either the DC/TMD or RDC/TMD for TMD diagnosis and either the PSQI, SAQ or ESS questionnaires for sleep assessment were included. Articles selected for meta-analysis underwent quality, heterogeneity and publication bias evaluation.

RESULTS

A total of 1071 articles were found by online search, and 10 articles were added manually. For full-text reading, 138 papers were selected. Thirty-six articles were included in the final review, and 19 in the meta-analysis (PSQI only). Subjective sleep quality was shown to be associated with all RDC/TMD or DC/TMD Axis I diagnostic groups: muscle disorders, arthralgia/osteoarthritis/osteoarthrosis and disk displacements; with the highest association in the first two groups, and the lowest in the last one. A 4.45 times increased odds ratio of TMD prevalence was found for individuals who presented poor subjective sleep quality.

CONCLUSION

Subjective sleep quality should be considered in the management of TMD.

Depressive symptoms account for differences between self-reported versus polysomnographic assessment of sleep quality in women with myofascial TMD

Patients with temporomandibular disorder (TMD) report poor sleep quality on the Pittsburgh Sleep Quality Index (PSQI). However, polysomnographic (PSG) studies show meagre evidence of sleep disturbance on standard physiological measures. The present aim was to analyse self-reported sleep quality in TMD as a function of myofascial pain, PSG parameters and depressive symptomatology. PSQI scores from 124 women with myofascial TMD and 46 matched controls were hierarchically regressed onto TMD presence, ratings of pain intensity and pain-related disability, in-laboratory PSG variables and depressive symptoms (Symptoms Checklist-90). Relative to controls, TMD cases had higher PSQI scores, representing poorer subjective sleep and more depressive symptoms (both P < 0·001). Higher PSQI scores were strongly predicted by more depressive symptoms (P < 0·001, R² = 26%). Of 19 PSG variables, two had modest contributions to higher PSQI scores: longer rapid eye movement latency in TMD cases (P = 0·01, R² = 3%) and more awakenings in all participants (P = 0·03, R² = 2%). After accounting for these factors, TMD presence and pain ratings were not significantly related to PSQI scores. These results show that reported poor sleep quality in TMD is better explained by depressive symptoms than by PSG-assessed sleep disturbances or myofascial pain. As TMD cases lacked typical PSG features of clinical depression, the results suggest a negative cognitive bias in TMD and caution against interpreting self-report sleep measures as accurate indicators of PSG sleep disturbance. Future investigations should take account of depressive symptomatology when interpreting reports of poor sleep.

The effect of sleep deprivation on pain perception in healthy subjects: a meta-analysis

BACKGROUND

There is strong evidence indicating an interaction between sleep and pain. However, the size of this effect, as well as the clinical relevance, is unclear. Therefore, this meta-analysis was conducted to quantify the effect of sleep deprivation on pain perception.

METHODS

A systematic literature search was conducted using the electronic databases PubMed, Cochrane, Psyndex, Psycinfo, and Scopus. By conducting a random-effect model, the pooled standardized mean differences (SMDs) of sleep deprivation on pain perception was calculated. Studies that investigated any kind of sleep deprivation in conjunction with a pain measurement were included. In cases of several pain measurements within a study, the average effect size of all measures was calculated.

RESULTS

Five eligible studies (N = 190) for the between-group analysis and ten studies (N = 266) for the within-group analysis were identified. Sleep deprivation showed a medium effect in the between-group analysis (SMD = 0.62; CI95: 0.12, 1.12; z = 2.43; p = 0.015) and a large effect in the within-group analysis (SMD = 1.49; CI95: 0.82, 2.17; z = 4.35; p <0.0001). The test for heterogeneity was not significant in the between-group analysis (Q = 5.29; df = 4; p = 0.2584), but it was significant in the within-group analysis (Q = 53.49; df = 9; p <0.0001).

CONCLUSION

This meta-analysis confirms a medium effect (SMD = 0.62) of sleep deprivation on pain perception. As this meta-analysis is based on experimental studies in healthy subjects, the clinical relevance should be clarified.

Test-retest reliability of thermal temporal summation using an individualized protocol

Temporal summation (TS) refers to the increased perception of pain with repetitive noxious stimuli. It is a behavioral correlate of wind-up, the spinal facilitation of recurring C-fiber stimulation. In order to utilize TS in clinical pain research, it is important to characterize TS in a wide range of individuals and to establish its test-retest reliability. Building on a fixed-parameter protocol, we developed an individually adjusted protocol to broadly capture thermally generated TS. We then examined the test-retest reliability of TS within-day (intertrial intervals ranging from 2 to 30 minutes) and between-days (intersession interval of 7 days). We generated TS-like effects in 19 of the 21 participants. Strong correlations were observed across all trials over both days (intraclass correlation [ICC] [A, 10] = .97, 95% confidence level [CL] = .94-.99) and across the initial trials between days (ICC [A, 1] = .83, 95% CL = .58-.93). Repeated measures mixed-effects modeling demonstrated no significant within-day variation and only a small (5 out of 100 points) between-day variation. Finally, a Bland-Altman analysis suggested that TS is reliable across the range of observed scores. Without intervention, thermally-generated TS is generally stable within day and between days.

PERSPECTIVE

Our study introduces a new strategy to generate thermal TS in a high proportion of individuals. This study confirms the test-retest reliability of thermal TS, supporting its use as a consistent behavioral correlate of central nociceptive facilitation.

Understanding central mechanisms of acupuncture analgesia using dynamic quantitative sensory testing: a review

We discuss the emerging translational tools for the study of acupuncture analgesia with a focus on psychophysical methods. The gap between animal mechanistic studies and human clinical trials of acupuncture analgesia calls for effective translational tools that bridge neurophysiological data with meaningful clinical outcomes. Temporal summation (TS) and conditioned pain modulation (CPM) are two promising tools yet to be widely utilized. These psychophysical measures capture the state of the ascending facilitation and the descending inhibition of nociceptive transmission, respectively. We review the basic concepts and current methodologies underlying these measures in clinical pain research, and illustrate their application to research on acupuncture analgesia. Finally, we highlight the strengths and limitations of these research methods and make recommendations on future directions. The appropriate addition of TS and CPM to our current research armamentarium will facilitate our efforts to elucidate the central analgesic mechanisms of acupuncture in clinical populations.