Is maximal strength of the cervical flexor muscles reduced in patients with temporomandibular disorders?

The effectiveness of cervical rehabilitation interventions for pain in adults with myogenic temporomandibular disorders: A systematic review and meta-analysis

OBJECTIVE

Little evidence exists for the most effective conservative treatment approach for adults with myogenic temporomandibular disorders (MTMD). We aim to assess the effectiveness of cervical rehabilitation interventions on pain intensity and sensitivity in adults with MTMD compared to comparison intervention such as placebo, sham treatment, education or no intervention.

METHODS

For this systematic review and meta-analysis, we searched PubMed, EMBASE, Medline, PEDro databases, forward and backward citations and grey literature studies through PROSPERO, clinical trials and data registries without language or date restrictions between inception and 1 December 2021. We selected randomised controlled trials (RCTs) based on adult populations with MTMD who had a cervical rehabilitation intervention which was defined as any conservative intervention targeting the anatomical structures of the cervical spine. The primary outcome measures for pain were self-reported pain intensity and pain sensitivity through the pressure pain threshold (PPT) of the masseter and temporalis muscles. Secondary outcome measures of maximal mouth opening (on MMO) were included. Included studies were assessed for bias with the Cochrane risk of bias tool for randomised trials. Evidence from RCTs was synthesised to determine treatment effect size as differences between standardised mean difference (SMD) for changes in pain intensity, PPT and MMO comparing adults with MTMD who were treated with cervical rehabilitation interventions compared to a control group. This study is registered on Prospero, number CRD 42021289299.

RESULTS

Our general search yielded 2647 studies where seven RCTs met eligibility criteria with low to some concerns in their risk of bias. Pain intensity (five studies, n = 223, SMD -0.98, 95% CI -1.67 to -0.28, I2 = 79%), PPT of the masseter muscle (six studies, n = 395, SMD 0.64, 95% CI 0.43 to 0.86, I2 = 90%) and the temporalis muscles (five studies, n = 295, SMD 0.76, 95% CI 0.07 to 1.45, I2 = 84%) showed large treatment effect estimates favouring cervical rehabilitation interventions compared to no treatment, sham cervical treatment, patient education or non-cervical neuromuscular techniques. Compared to control interventions, one type of cervical rehabilitation intervention, cervical manual therapy alone or in combination with a neck exercise program was associated with statistically significant, large treatment effect estimates on pain intensity (four studies, n = 203, SMD -1.52, 95% CI -2.50 to -0.55).

CONCLUSIONS

This review found that in the short-term, cervical rehabilitation interventions especially upper cervical MT alone or in combination with a neck exercise program are effective in improving multiple pain outcomes in adults with MTMD. However, further research is needed to measure the long-term effects of this type of intervention.

An investigation of biomechanics, muscle performance, and disability level of craniocervical region of individuals with temporomandibular disorder

OBJECTIVE

To investigate biomechanics, muscle performance, and disability of the craniocervical region in temporomandibular disorder (TMD) patients and compare them with controls.

METHODS

Craniocervical posture was evaluated using lateral photography and radiography. Range of motion, muscle performance, disability, and TMD severity were assessed using an inclinometer, Functional Strength Testing of Cervical Spine, Neck Disability Index, and Fonseca Anamnestic Index, respectively.

RESULTS

Compared to the control group, the TMD group demonstrated higher cervical flexion angle (p=0.005) and neck disability (p<0.001) as well as lower cervical extension (p=0.040), right cervical rotation (p=0.005), left cervical rotation (p<0.001), and tragus-C7-horizontal (p=0.048) angles, and reduced muscle performances (p≤0.001). Most patients had higher than normal craniocervical angle (p<0.001). Muscle performance in each cervical motion (p<0.005) and disability (p<0.001) were associated with TMD severity in the TMD group.

CONCLUSION

Biomechanics, muscle performance, and disability of craniocervical region were altered in the TMD group.

Reference Values for Cervical Muscle Strength in Healthy Women Using a Hand-Held Dynamometer and the Association with Age and Anthropometric Variables

Knowledge of reference values for cervical muscle strength is a key tool for clinicians to use as a clinical reference measure and to establish goals during rehabilitation. The objective was to establish reference values for the maximal strength of cervical muscles in healthy women using a handheld dynamometer and verify the association of cervical muscle strength with age and anthropometric measurements. A hundred women were classified into four groups (n = 25) according to age: 18-29 years, 30-39 years, 40-49 years, and 50-60 years. Maximal muscle strength of the cervical spine was measured using a Lafayette® handheld dynamometer for flexion, extension, and bilateral lateral flexion. No differences in cervical muscle strength were observed among the groups (p > 0.05). However, the 18-29-year-old group took less time to reach the peak of force for flexion than the 50-60-year-old group. Moderate correlations were observed between cervical flexor strength and weight, body mass index, and neck circumference, and between cervical extensor strength and weight and body mass index (r = 0.43-0.55; p < 0.05). Reference values for cervical muscle strength in healthy women were established using a handheld dynamometer, and the association between muscle strength and anthropometric data was moderate.

Investigation of the predictors of temporomandibular disorders in engineers across different variables: sociodemographic characteristics, neck pain and neck awareness

PURPOSE/AIM

This study aimed to investigate the predictors of temporomandibular disorders (TMD) in desk-bound engineers.

MATERIALS AND METHODS

The Fonseca Anamnestic Index (FAI), The Visual Analogue Scale (VAS), The Neck Pain and Disability Scale (NPDS), Neck Bournemouth Questionnaire (NBQ) and The Fremantle Neck Awareness Questionnaire-Turkish (FreNAQ-T) were used for TMD severity, pain, disability, neck awareness.

RESULTS

The study was conducted with 208 desk-bound engineers. Mild-to-severe TMD was detected in 78.9% of the subjects. Intensity of pain at rest and during activity was higher in female engineers compared to male engineers (p = 0.002 and <0.01, respectively) and mean FAI, NBQ, NPDS and FreNAQ-T scores were also higher than that of male engineers (p = 0.005, 0.005, 0.006 and 0.016, respectively). FAI, VAS, NPDS, NBQ and FreNAQ-T were found to be correlated with each other (p < 0.05). A statistically significant contribution to the regression model was observed for the variables gender, daily duration of computer use, neck pain at rest, and NBQ (p = 0.043, p = 0.043, p = 0.031 and p = 0.003, respectively). NBQ was identified as the most influential variable in this model, followed by neck pain at rest.

CONCLUSIONS

Temporomandibular disorders are common among desk-bound engineers and are associated with neck pain, disability, and neck awareness. For this reason, it is important to take preventive and protective ergonomic approaches at the personal and institutional levels in desk-bound engineers.

White Matter Diffusion Properties in Chronic Temporomandibular Disorders: An Exploratory Analysis

Objective

To determine differences in diffusion metrics in key white matter (WM) tracts between women with chronic temporomandibular disorders (TMDs) and age- and sex-matched healthy controls.

Design

Cross sectional study compared diffusion metrics between groups and explored their associations with clinical variables in subjects with TMDs.

Methods

In a total of 33 subjects with TMDs and 33 healthy controls, we performed tractography to obtain diffusion metrics (fractional anisotropy [FA], mean diffusivity [MD], radial diffusivity [RD], and axial diffusivity [AD]) from the cingulum near the cingulate gyrus (CGC), the cingulum near the hippocampus (CGH), the fornix, the anterior limb of the internal capsule (ALIC), the posterior limb of the internal capsule (PLIC), and the uncinate fasciculus (UF). We compared diffusion metrics across groups and explored the relationships between diffusion metrics and clinical measures (pain chronicity and intensity, central sensitization, somatization, depression, orofacial behavior severity, jaw function limitations, disability, and interference due to pain) in subjects with TMDs.

Results

We observed differences in diffusion metrics between groups, primarily in the right side of the brain, with the right CGC having lower FA and the right UF having lower FA and higher MD and RD in subjects with TMDs compared to healthy controls. No clinical measures were consistently associated with diffusion metrics in subjects with TMDs.

Conclusion

The UF showed potential microstructural damage in subjects with TMDs, but further studies are needed to confirm any associations between diffusion changes and clinical measures.

Are neck pain, disability, and deep neck flexor performance the same for the different types of temporomandibular disorders?

OBJECTIVE

To evaluate neck pain, disability, and deep neck flexor (DNF) performance of individuals with temporomandibular disorders (TMD).

METHODS

Eighty individuals were divided into the following: arthrogenic TMD (n = 40), myogenic TMD (n = 12), and mixed TMD (n = 28). Neck pain intensity, neck disability, and DNF performance were evaluated.

RESULTS

Individuals with arthrogenic TMD reported lower intensity of neck pain when compared to mixed TMD (p = 0.01). Individuals with arthrogenic TMD had less neck disability than individuals with myogenic TMD (p = 0.037) and mixed TMD (p < 0.001). A moderate positive correlation was found between neck pain and neck disability (p < 0.001). No differences were found for DNF performance.

CONCLUSION

Neck pain and disability differs according to subtype of TMD, but performance of the deep neck flexors does not. Neck pain intensity and neck disability were correlated in patients with TMD.

Smartphone addiction and the relationship with head and neck pain and electromiographic activity of masticatory muscles

BACKGROUND

Excessive use of smartphones may be associated with behavioral and physical health changes and might cause musculoskeletal alterations in the head and neck region.

OBJECTIVE

To evaluate the prevalence of smartphone addiction in college students and its correlation with symptoms of head and neck pain and masticatory and trapezius muscle activity while resting, before and after smartphone use.

METHODS

Twenty university students participated in the study. They answered the Smartphone Addiction Scale and the Fonseca Anamnestic Index. Next, the participants were seated and prepared for electromyography through the placement of surface electrodes on the masseter, temporal, and trapezius muscles. Rest condition data were collected for 10 seconds before and after 30 minutes of smartphone use.

RESULTS

The results showed that 35% of the evaluated individuals were classified as smartphone addicted and 35% reported no head or neck pain in the previous 30 days. There was no association between smartphone use and head and neck pain. In the electromyography, there was an increase in RMS values after smartphone use in the right and left masseter muscles and the left trapezius.

CONCLUSION

College students presented a high prevalence of smartphone addiction and head and neck pain, but these were not statistically associated. There was a change in muscle activity only in the right trapezius muscles before and after 30 minutes of smartphone use. These findings are contrary to the current belief that the use of smartphones correlates with pain in the neck region and changes in the electrical muscle activity, leading to fatigue in the cervical muscles.

The association between specific temporomandibular disorders and cervicogenic headache

BACKGROUND AND AIMS

Upper neck signs, symptoms and hypomobility have been shown to present with a higher prevalence in patients with temporomandibular disorders (TMDs). However, there is currently no evidence of an association between specific TMDs and cervicogenic headache (CGH). Therefore, the aim of this study was to evaluate the odds ratio and the relative risk of CGH in patients with specific TMDs.

METHOD

116 participants, including 74 patients with TMD (pain-related/intraarticular/mixed TMD) and 42 healthy controls took part in this study. The TMD diagnosis was made by senior faculty members of the Dental School according to the Diagnostic Criteria for TMD, while the cervical diagnosis was made by a qualified senior physical therapist. The analysis comprised the evaluation of the odds ratio of CGH among patients with TMD and the relative risk (RR) for CGH during 14-24 months of follow-up.

RESULTS

Significantly higher odds ratios of cervicogenic headache were found among pain-related and mixed TMD (12.17 and 10.76, respectively) versus healthy controls. During the 14-24 months of follow-up, there was no significant difference of relative risk for CGH among patients with TMD versus healthy controls.

SUMMARY AND CONCLUSIONS

The results support a clear clinical association between painful TMD (pain-related and mixed TMD) and cervicogenic headache.

Cervical musculoskeletal disorders in patients with temporomandibular dysfunction: A systematic review and meta-analysis

OBJECTIVE

To verify which are the neck musculoskeletal disorders presented by individuals with temporomandibular disorders (TMD).

METHODS

It is a systematic review and meta-analysis that were included cohort, case-control and cross-section studies that analyzed the presence of cervical musculoskeletal disorders in individuals with TMD, with age between 18 and 55 years. The searches were carried out in the databases: Medline/PubMed, Cinahl, Web of Science, Cochrane, Lilacs and Scopus; and there was no linguistic or temporal restriction. The evidence quality was evaluated by GRADE system and methodological quality by Newcastle-Ottawa Quality Assessment Scale (NOS) and the risk of publication bias assessed by the funnel plot graph. The data was quantitatively analyzed by the meta-analysis using the mean differences (MD) as an effect measure.

RESULTS

There were included 21 manuscripts in the synthesis, of theses 16 were evaluated by meta-analysis with methodological quality ranging from poor to excellent by NOS scale. Individuals with TMD present lower endurance of extensor neck muscle compared to TMD-free (MD = -194.66s [95%CI: 212.44;-176.88]), with moderate to excellent quality. As, upper neck hymobility on the right (MD = -8.59° (95%CI: -10.43°;-6.75°) and left (MD = -7.99° (95%CI: -9.63°;-6.35°), and in all global neck movements. Also, individuals with TMD presented worse self-reported neck disability (MD = 7.91 (95%CI: 7.39; 8.43)) compared to free-TMD.

CONCLUSION

There is moderate and strong evidence that patients with TMD present lower endurance of extensor neck muscle, global and upper neck hypomobility, worse self-reported neck disability, however, their cranio-cervical posture is similar to individuals without TMD, based on a moderate to excellent methodological quality.

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO CRD42018103918.

Craniocervical and Cervical Spine Features of Patients with Temporomandibular Disorders: A Systematic Review and Meta-Analysis of Observational Studies

To assess neck disability with respect to jaw disability, craniocervical position, cervical alignment, and sensorimotor impairments in patients with temporomandibular disorders (TMD), a systematic review and meta-analysis of observational studies trials were conducted. The meta-analysis showed statistically significant differences in the association between neck disability and jaw disability (standardized mean difference (SMD), 0.72 (0.56-0.82)). However, results showed no significant differences for cervical alignment (SMD, 0.02 (-0.31-0.36)) or for the craniocervical position (SMD, -0.09 (-0.27-0.09)). There was moderate evidence for lower pressure pain thresholds (PPT) and for limited cervical range of motion (ROM). There was limited evidence for equal values for maximal strength between the patients with TMD and controls. There was also limited evidence for reduced cervical endurance and conflicting evidence for abnormal electromyographic (EMG) activity and motor control in TMD patients. Results showed a clinically relevant association between cervical and mandibular disability in patients with TMD. Regarding sensory-motor alterations, the most conclusive findings were observed in the reduction of PPT and cervical ROM, with moderate evidence of their presence in the patients with TMD. Lastly, the evidence on impaired motor control and cervical EMG activity in patients with TMD was conflicting.

Relationship between specific temporomandibular disorders and impaired upper neck performance

Upper neck impairments are more prevalent in patients with temporomandibular disorders (TMDs) but the differences between specific types of TMDs are unclear. This study evaluated the distribution of such impairments among different forms of TMD. In total, 116 participants (86 women and 30 men, age range 21-75 yr) were investigated. Forty-two individuals had no TMDs and were assigned to the control group. The remaining 74 patients were assigned to one of three groups based on the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) findings: pain-related (n = 37); intra-articular (n = 17); or mixed (combined pain-related and intra-articular) (n = 20). Analyses of impairments included between-group comparisons of key parameters of upper neck performance (active/passive mobility and muscular capabilities) and pain (subjective neck disability and pain sensitivity). Patients in the pain-related and mixed TMD groups were found to have decreased upper neck mobility in the cervical flexion-rotation test compared with patients in intra-articular and control groups, as well as poorer capabilities of the deep neck flexor muscles in the cranio-cervical flexion test compared to the control group. It was concluded that patients with pain-related TMD diagnoses are more likely to experience significant upper-neck hypomobility and poor muscular capabilities than patients with intra-articular diagnoses of TMD.

Temporomandibular dysfunction affects aerobic capacity in females: A preliminary study

Objective: The purpose of this study was to investigate the aerobic capacity in patients with temporomandibular dysfunction (TMD) and to compare the results with those of the asymptomatic individuals.Methods: The TMD group included a total of 31 females between the ages of 18 and 25 years. The control group consisted of 31 asymptomatic females with an age range of 18 to 27 years. A graded exercise test was performed using an electronically braked arm crank ergometer. An indirect calorimeter system was used to calculate the peak oxygen consumption (VO₂peak). In addition, peak heart rate (HR_peak) and respiratory quotient were calculated for each participant.Results: The TMD group had lower VO₂peak (p = 0.017) and HRpeak (p = 0.012) in aerobic capacity tests; however, respiratory quotient was similar in both groups (p = 0.446).Discussion: The TMD group had lower aerobic capacity compared to the asymptomatic individuals.

Relationship Between Headaches and Neck Pain Characteristics With Neck Muscle Strength

OBJECTIVE

The purpose of this study was to assess the correlations between neck muscle strength and pain features, such as neck-related disability, neck pain frequency and intensity, and headache frequency in women with headache.

METHODS

Seventy women with migraine between 18 and 55 years of age diagnosed according to International Headache Society criteria were assessed. Participants provided clinical information regarding neck pain and headache. The Neck Disability Index was used to assess neck-related disability, and neck muscle strength was assessed via maximum voluntary contraction during flexion, extension, and lateral flexion with a handheld dynamometer. The correlation was verified with Spearman's correlation coefficient (ρ). Multiple linear regression was performed to verify whether the clinical variables could predict the strength of neck muscles. All calculations were performed adopting a level of significance of 0.05.

RESULTS

Neck extensor strength was negatively correlated with all clinical variables (ρ_range = -.24 to -.32, p < .05); lateral flexor strength was negatively correlated with headache frequency, neck pain intensity, and neck-related disability (ρ_range = -.27 to -.39, p < .05); and flexor strength also correlated negatively with neck pain intensity and related disability (ρ_r = -.26 to -.29, p < .05). Headache frequency and neck pain intensity were identified as significant predictors of the strength variability in extension (R² = 0.16, p < .05) and in lateral flexion (R² = 0.18, p < .05).

CONCLUSIONS

For the women with migraine in this study, correlations of headache and neck pain with neck muscle strength features were weakly to moderately negative. Headache frequency and neck pain intensity may influence a small proportion of the strength variability in extension and lateral flexion.

Cervical-scapular muscles strength and severity of temporomandibular disorder in women with mechanical neck pain

Abstract Introduction: Changes in cervical muscle function have been observed in patients with neck pain (NP) and TMD. However, the relationship between TMD severity and neck muscle strength in the presence/absence of NP is unknown. Objective: To determine the prevalence of TMD in women with and without mechanical NP and assess the cervical-scapular muscle strength and its association with TMD severity. Methods: Fifteen volunteers without neck pain (CG) and 14 women with mechanical neck pain (NPG) took part and were selected by the Neck Disability Index. The diagnosis and severity of TMD were determined by the Research Diagnostic Criteria for TMD and Temporomandibular Index (TI), respectively. The strength of the upper trapezius muscle, and cervical flexor and extensor muscles was measured by digital hand dynamometer. Results: 64.5% of women with NP and 33.3% without NP were diagnosed with TMD (p = 0.095). The NPG showed lower strength of the cervical flexor (p = 0.044) and extensor (p=0.006) muscles, and higher TI (p = 0.038) than in the CG. It was also verified moderate negative correlation between TI and the strength of dominant (p = 0.046, r = -0.547) and non-dominant (p = 0.007, r = -0.695) upper trapezius, and cervical flexors (p = 0.023, r = -0.606) in the NPG. Conclusion: There was no difference in the prevalence of TMD in women with and without NP. However, women with NP have lower cervical muscle strength - compared to those without NP - which was associated with greater severity of TMD. Thus, in women with NP associated with TMD, it is advisable to assess and address the severity of this dysfunction and identify the cervical-scapular muscles compromise.

Cervical Muscle Strength and Muscle Coactivation During Isometric Contractions in Patients With Migraine: A Cross-Sectional Study

OBJECTIVES

This cross-sectional study investigated potential differences in cervical musculature in groups of migraine headaches vs. non-headache controls. Differences in cervical muscle strength and antagonist coactivation during maximal isometric voluntary contraction (MIVC) were analyzed between individuals with migraine and non-headache subjects and relationships between force with migraine and neck pain clinical aspects.

METHOD

A customized hand-held dynamometer was used to assess cervical flexion, extension, and bilateral lateral flexion strength in subjects with episodic migraine (n=31), chronic migraine (n = 21) and healthy controls (n = 31). Surface electromyography (EMG) from sternocleidomastoid, anterior scalene, and splenius capitis muscles were recorded during MIVC to evaluate antagonist coactivation. Comparison of main outcomes among groups was conducted with one-way analysis of covariance with the presence of neck pain as covariable. Correlations between peak force and clinical variables were demonstrated by Spearman's coefficient.

RESULTS

Chronic migraine subjects exhibited lower cervical extension force (mean diff. from controls: 4.4 N/kg; mean diff from episodic migraine: 3.7 N/kg; P = .006) and spent significantly more time to generate peak force during cervical flexion (mean diff. from controls: 0.5 seconds; P = .025) and left lateral-flexion (mean diff. from controls: 0.4 seconds; mean diff. from episodic migraine: 0.5 seconds; P = .007). Both migraine groups showed significantly higher antagonist muscle coactivity of the splenius capitis muscle (mean diff. from controls: 20%MIVC, P = .03) during cervical flexion relative to healthy controls. Cervical extension peak force was moderately associated with the migraine frequency (rs: -0.30, P = .034), neck pain frequency (rs: -0.26, P = .020), and neck pain intensity (rs: -0.27, P = .012).

CONCLUSION

Patients with chronic migraine exhibit altered muscle performance, took longer to reach peak of force during some cervical movements, and had higher coactivation of the splenius capitis during maximal isometric cervical flexion contraction. Finally, patients with migraine reported the presence of neck and head pain complaints during maximal isometric voluntary cervical contractions.

Cervical musculoskeletal impairments and temporomandibular disorders

Objectives

The study of cervical muscles and their significance in the development and perpetuation of Temporomandibular Disorders has not been elucidated. Thus this project was designed to investigate the association between cervical musculoskeletal impairments and Temporomandibular Disorders.

Material and Methods

A sample of 154 subjects participated in this study. All subjects underwent a series of physical tests and electromyographic assessment (i.e. head and neck posture, maximal cervical muscle strength, cervical flexor and extensor muscles endurance, and cervical flexor muscle performance) to determine cervical musculoskeletal impairments.

Results

A strong relationship between neck disability and jaw disability was found (r = 0.82). Craniocervical posture was statistically different between patients with myogenous Temporomandibular Disorders (TMD) and healthy subjects. However, the difference was too small (3.3º) to be considered clinically relevant. Maximal cervical flexor muscle strength was not statistically or clinically different between patients with TMD and healthy subjects. No statistically significant differences were found in electromyographic activity of the sternocleidomastoid or the anterior scalene muscles in patients with TMD when compared to healthy subjects while executing the craniocervical flexion test (P = 0.07). However, clinically important effect sizes (0.42 - 0.82) were found. Subjects with TMD presented with reduced cervical flexor as well as extensor muscle endurance while performing the flexor and extensor muscle endurance tests when compared to healthy individuals.

Conclusions

Subjects with Temporomandibular Disorders presented with impairments of the cervical flexors and extensors muscles. These results could help guide clinicians in the assessment and prescription of more effective interventions for individuals with Temporomandibular Disorders.