Interrater and Intrarater Reliability of a Handheld Myotonometer in Measuring Mechanical Properties of the Neck and Orofacial Muscles

MyotonPRO as a new valid tool for measuring cervical muscle tension. A reliability study

OBJECTIVE

The main objective of this study is to test the reliability of a non-invasive objective method for the measurement of biomechanical parameters of cervicofacial muscle groups, with the purpose of diagnosis and evaluation of voice disorders' treatments, especially focused on muscle tension dysphonia.

STUDY DESIGN

Prospective study.

METHODS

The device used is a handheld myotonometer (MyotonPRO) that measures biomechanical and viscoelastic properties in superficial soft tissues frequency, stiffness, elasticity, relaxation time and creep. It is used in the field of medicine, sport and research. This pilot study includes 10 subjects, who have been measured in the masseter, sternocleidomastoid, orbicularis oris, semispinalis capitis, suprahyoid, infrahyoid and trapezius muscles on each side. Measurements were performed by 2 evaluators to assess inter-evaluator reliability. Subsequently, one of them repeated the measurements to assess intra-evaluator reliability.

RESULTS

The results revealed good to excellent inter-rater reliability for the masseter, sternocleidomastoid, trapezius and suprahyoid muscles, with lower ICCs for the stiffness and creep properties. Intra-rater reliability was good to excellent for the masseter, sternocleidomastoid, semispinalis capitis and suprahyoid muscles. The lowest ICCs were found in the stiffness and creep properties.

CONCLUSION

The use of a myotonometer to measure the mechanical properties of selected cervical and orofacial muscles is a reliable and reproducible method. Future research is needed to establish an association between the properties of these muscles and their role in voice disorders, as well as to determine whether this tool can aid diagnosis with quantifiable and objectifiable indicators, and for monitoring and treatment efficacy.

The Effects of Cervical Mobilization with Clinical Pilates Exercises on Pain, Muscle Stiffness and Head and Neck Blood Flow in Cervicogenic Headache: Randomized Controlled Trial

Background and Objectives: Physiotherapy approaches are used to eliminate the problems caused by cervicogenic headache (CHA), known as secondary headache associated with the structures of the upper cervical region. This study aimed to investigate the effects of cervical mobilization (CM) with clinical Pilates exercises (CPE) on pain, muscle stiffness and head-neck blood flow in CGH. Materials and Methods: A total of 25 patients participated in this randomized controlled study and were randomized into either the CM group or the CM+CPE group. All treatment methods were applied 3 days a week for 6 weeks. The outcome measure was headache intensity and frequency, the number of analgesics, muscle stiffness and vertebral artery (VA) and internal carotid artery (ICA) blood flow. Headache intensity was measured by a visual analogue scale, muscle stiffness by a myotonometer and blood flow by Doppler US. Evaluations were repeated after 6 weeks of treatment. Within-group comparisons were made by the Wilcoxon signed rank test, and between-group comparisons were made by the Mann-Whitney U test. Results: After treatments in the two groups, headache intensity and frequency and the number of analgesics decreased, the muscle stiffness of the suboccipital, upper trapezius and sternocleidomastoid (SCM) muscles decreased, and the blood flow of the ICA and VA increased (p < 0.05). There was a significant difference between the groups in terms of headache intensity (p = 0.025) and muscle stiffness in SKM (p = 0.044) in favor of the CM+CPE group. Conclusions: Non-pharmacological treatment approaches have an important role in CHA related to the upper cervical region. This study suggests that it would be beneficial to add CM in combination with CPE to the non-pharmacological treatment of patients with CHA.

An investigation of the changes in mechanical properties of the orofacial and neck muscles between patients with myogenous and mixed temporomandibular disorders

OBJECTIVE

To investigate the possible changes in the mechanical properties of the orofacial and neck muscles in patients with temporomandibular disorders (TMD).

METHODS

The study included a total of 98 females. Females were divided into three groups as myogenous TMD, mixed TMD, and healthy controls. The frequency (indicator of muscle tone), stiffness, and decrement (related to muscle elasticity) values of the sternocleidomastoid, upper trapezius, cervical extensor, and masseter muscles were measured using a portable myotonometer.

RESULTS

The frequency, stiffness, and decrement values of the masseter muscle were higher in the mixed and myogenous TMD groups than those of the control group (p < 0.017). The mixed TMD group had higher frequency and stiffness values in the upper trapezius muscle compared with the control group (p < 0.017).

DISCUSSION

The results suggest that the mechanical properties of the oral and neck muscles may be affected in patients with TMD.

Biomechanical properties of masseter muscle assessed through myotonometry in patients with temporomandibular disorder treated with ultrasound therapy: a randomized comparative study

BACKGROUND

The aim of the study was to make an objective quantitative assessment of effectiveness of procedures with the use of a therapeutic dose of ultrasounds in this nosological entity, in connection with improved biomechanical properties and alleviation of pain experienced in masseter muscles.

METHODS

The study included 40 patients with temporomandibular disorder. In group 1 (N.=20) ultrasound therapy (1.2 W/cm2) was carried out, while in group 2 (N.=20) sham therapy was applied. A total of 10 procedures were performed. Myotonometric measurements and assessment of pain intensity were carried out before treatment and after the completion of procedures.

RESULTS

The analysis revealed a significant difference (P=0.011) between the values of decrement (D) measured on day 0 (2.08±0.45 [log]) and day 4 (1.80±0.55 [log]) in group 1. In group 2 no statistically significant differences were noted between the results obtained on consecutive days of the therapeutic cycle. A statistically significant difference in values of decrement (D) between group 1 (1.80±0.55 [log]) and group 2 (2.23±0.51 [log]) was noted on day 4 of the experiment (P=0.021). Both in group 1 and in group 2, a statistically significant reduction of pain intensity (VAS Scale) was obtained.

CONCLUSIONS

The masseter muscle was more elastic during ultrasound therapy. However, the effect was transient. The analgesic effect was also observed in the control group; therefore, a placebo effect cannot be excluded.

A deep dive into the static force transmission of the human masticatory system and its biomechanical effects on the temporomandibular joint

OBJECTIVE

This study aims to investigate the biomechanical behavior and reveal the force transmission patterns of the human masticatory system through advanced three-dimensional finite element (FE) models.

METHODS

The FE model was constructed according to the medical images of a healthy male adult. It contains full skull structures, detailed temporomandibular joints (TMJs) with discs, complete dentitions, masticatory muscles, and related ligaments. Several static bite scenarios were simulated to demonstrate the effects of bite positions and muscle force recruitments on the force transmission patterns.

RESULTS

Molar occlusal surfaces are the primary force transmission region for clenching. Sensitivity analysis demonstrated that the stiffness of the bite substance would not alter the force transmission patterns but could affect the maximum contact stresses on the discs and the occlusal surfaces. During the unilateral clenching tasks, the high-stress region on the discal surfaces shifted ipsilaterally. The presence or absence of the molar cushions would significantly affect the biomechanical response of the masticatory system.

SIGNIFICANCE

FE analysis is an effective way of investigating biomechanical responses involving complicated interactions. Enriching the static analysis of the masticatory system with a detailed model can help understand better how the forces were transmitted and the significance of TMJs during the clenching process.

Effect of osteopathic techniques on human resting muscle tone in healthy subjects using myotonometry: a factorial randomized trial

Musculoskeletal disorders (MSDs) are highly prevalent, burdensome, and putatively associated with an altered human resting muscle tone (HRMT). Osteopathic manipulative treatment (OMT) is commonly and effectively applied to treat MSDs and reputedly influences the HRMT. Arguably, OMT may modulate alterations in HRMT underlying MSDs. However, there is sparse evidence even for the effect of OMT on HRMT in healthy subjects. A 3 × 3 factorial randomised trial was performed to investigate the effect of myofascial release (MRT), muscle energy (MET), and soft tissue techniques (STT) on the HRMT of the corrugator supercilii (CS), superficial masseter (SM), and upper trapezius muscles (UT) in healthy subjects in Hamburg, Germany. Participants were randomised into three groups (1:1:1 allocation ratio) receiving treatment, according to different muscle-technique pairings, over the course of three sessions with one-week washout periods. We assessed the effect of osteopathic techniques on muscle tone (F), biomechanical (S, D), and viscoelastic properties (R, C) from baseline to follow-up (primary objective) and tested if specific muscle-technique pairs modulate the effect pre- to post-intervention (secondary objective) using the MyotonPRO (at rest). Ancillary, we investigate if these putative effects may differ between the sexes. Data were analysed using descriptive (mean, standard deviation, and quantiles) and inductive statistics (Bayesian ANOVA). 59 healthy participants were randomised into three groups and two subjects dropped out from one group (n = 20; n = 20; n = 19-2). The CS produced frequent measurement errors and was excluded from analysis. OMT significantly changed F (-0.163 [0.060]; p = 0.008), S (-3.060 [1.563]; p = 0.048), R (0.594 [0.141]; p < 0.001), and C (0.038 [0.017]; p = 0.028) but not D (0.011 [0.017]; p = 0.527). The effect was not significantly modulated by muscle-technique pairings (p > 0.05). Subgroup analysis revealed a significant sex-specific difference for F from baseline to follow-up. No adverse events were reported. OMT modified the HRMT in healthy subjects which may inform future research on MSDs. In detail, MRT, MET, and STT reduced the muscle tone (F), decreased biomechanical (S not D), and increased viscoelastic properties (R and C) of the SM and UT (CS was not measurable). However, the effect on HRMT was not modulated by muscle-technique interaction and showed sex-specific differences only for F.Trial registration German Clinical Trial Register (DRKS00020393).

Reliability of a New Indentometer Device for Measuring Myofascial Tissue Stiffness

Changes in tissue stiffness are associated with pathological conditions such as myofascial pain and increased risk of muscle injury. Furthermore, they have been shown to modify performance indicators such as running economy or jump height. Indentometry is an affordable way to assess tissue stiffness. However, to date, there is a paucity of studies examining the measurement properties of available devices. With this trial, we aimed to evaluate the reliability of the “IndentoPro”. Two investigators repeatedly measured the stiffness of the lateral head of the gastrocnemius muscle in healthy participants (N = 35), using 5 and 10 mm indentation depths. Intraclass Correlation Coefficients (ICC) revealed moderate inter-rater reliability (5 mm: ICC3,1 0.74, 95%CI = 0.54 to 0.86, p < 0.001; 10 mm: ICC3,1 0.59, 95%CI = 0.27 to 0.78, p < 0.001) and good intra-rater reliability (5 mm: ICC3,1 0.84, 95%CI = 0.71 to 0.92, p < 0.001; 10 mm: ICC3,1 0.83, 95%CI = 0.69 to 0.91, p < 0.001). No correlations between age, height, weight, BMI, skinfold thickness and myofascial tissue stiffness were observed (p > 0.5). In conclusion, the IndentoPro is reliable in assessing calf tissue stiffness, but the predictors of stiffness remain unclear.

Influence of Body Posture and Apnea Severity on the Tone and Elasticity of Upper Airway Muscles in Awake Patients With Obstructive Sleep Apnea: A Cross-Sectional Study

OBJECTIVE

The purpose of this study was to compare the effect of body posture and apnea severity on the tone, stiffness, and elasticity of upper airway muscles in awake patients with obstructive sleep apnea syndrome (OSAS).

METHODS

Eighty adult patients with OSAS from the Sleep Laboratory of the Bitlis State Hospital between April and December 2021 were included in the study. The tone, stiffness, and elasticity of the genioglossus and accessory muscles (sternocleidomastoid, masseter) were measured while the patients were awake, sitting upright, and in supine posture. According to polysomnography results and the Apnea-Hypopnea Index, patients were classified as mild, moderate, or severe OSAS.

RESULTS

There were 56 male (70%) and 24 female (30%) patients (age 45.0 ± 11.0 years). Tone of genioglossus, masseter, and sternocleidomastoid muscles were higher in supine than in sitting posture (all P < .05). There was no difference in elasticity scores of the bilateral genioglossus muscle in sitting and supine posture (P > .05). The elasticity scores of the sternocleidomastoid and masseter muscles were higher in sitting (all P < .05). An interaction effect of postural change and apnea severity was observed on stiffness scores of the genioglossus muscle (P < .05).

CONCLUSION

Results showed that the genioglossus muscle and accessory muscles take on the inspiratory load that develops with postural strain, regardless of the severity of apnea, in awake patients with OSAS. For participants measured in this study, accessory muscles supported respiration by increasing their elasticity.

Scapular Dynamic Muscular Stiffness Assessed through Myotonometry: A Narrative Review

Several tools have been used to assess muscular stiffness. Myotonometry stands out as an accessible, handheld, and easy to use tool. The purpose of this review was to summarize the psychometric properties and methodological considerations of myotonometry and its applicability in assessing scapular muscles. Myotonometry seems to be a reliable method to assess several muscles stiffness, as trapezius. This method has been demonstrated fair to moderate correlation with passive stiffness measured by shear wave elastography for several muscles, as well as with level of muscle contraction, pinch and muscle strength, Action Research Arm Test score and muscle or subcutaneous thickness. Myotonometry can detect scapular muscles stiffness differences between pre- and post-intervention in painful conditions and, sometimes, between symptomatic and asymptomatic subjects.

Gender-Related Biomechanical Properties of Masseter Muscle among Patients with Self-Assessment of Bruxism: A Comparative Study

It seems extremely important to know the biomechanical properties of the orofacial tissues among patients with increased activity of masticatory muscles, such as bruxism. The aim of this study was to evaluate biomechanical properties of the masseter muscle by using MyotonPRO in adults with probable bruxism and to define gender relations. This study was conducted in the Temporomandibular Disorders Department at Poznan University of Medical Sciences, Poland (June 2021-November 2021) among patients that reported bruxism symptoms The patients underwent a clinical examination, then the biomechanical properties of the masseter muscles were assessed. The MyotonPro measured masseter tone, stiffness and elasticity in 36 patients with a self-assessment of bruxism (18 women and 18 men). Data were collected from relaxed and contracted muscles. In relaxed masseter muscles there were no statistically significant differences between the sexes in muscle tone, stiffness and elasticity. During contraction significant differences were found between the sexes in the tension and the stiffness of the masseter muscles. Moreover, women often experienced headaches in the temporal region and pain in the masseter muscles during palpation. Among patients with a self-assessment of bruxism, accompanying pain was significantly more frequent in women. Male gender was associated with increased muscle tension and stiffness of the contracted masseter muscle.

Factors affecting subjective and objective masticatory function in older adults: Importance of an integrated approach

OBJECTIVES

This study aimed to subjectively and objectively assess masticatory function and identify related factors in older adults.

METHODS

From July 2017 to September 2018, we enrolled 115 healthy participants aged between 65 and 86 years. They underwent oral examination, and their stimulated salivary secretion rate and masseter muscle tone and biomechanical properties were assessed. Masticatory performance with two-colored chewing wax was objectively evaluated using the mixing ability index (MAI). Key food intake ability (KFIA) was subjectively assessed using a questionnaire.

RESULTS

The MAI score was significantly associated with the number of remaining teeth (r = 0.524, p < 0.001) and the tone (r = -0.222, p = 0.017), elasticity (r = -0.242, p = 0.009), and dynamic stiffness (r = -0.265, p = 0.004) of the masseter muscles. In contrast, the KFIA score was only significantly associated with the number of remaining teeth (r = 0.450, p < 0.001). A weak association between the MAI and KFIA scores was observed (r = 0.304, p = 0.001).

CONCLUSIONS

A combination of objective and subjective methods should be used to accurately assess masticatory function in older adults. In addition to physical factors such as the number of remaining teeth, properties of the masticatory muscles should be evaluated to improve the masticatory function of older adults.

CLINICAL SIGNIFICANCE

In addition to dental problems, various maxillofacial and oral factors must be considered when establishing management strategies for the improvement of masticatory function in older adults.

Biomechanical properties of the lips in a pre-orthodontic sample of adolescents and young adults

OBJECTIVES

To assess biomechanical properties of the lip muscles and to investigate their relationship with sex, age, body mass index (BMI), and cephalometric variables.

MATERIALS AND METHODS

Demographic information and BMI were collected from 83 study participants seeking orthodontic treatment at the University of Otago. Tone, stiffness, and elasticity of the lip muscles were measured thrice at four different anatomical sites using a digital palpation device. To estimate method error, a duplicate set of measurements in a subsample of 20 participants was taken a week later. Sagittal and vertical cephalometric classifications were based on ANB and FMPA angles, respectively. Data were analysed using mixed models.

RESULTS

Biomechanical properties of lip muscles were remarkably consistent both within and between different recording sessions. The lower lip had higher tone and stiffness than the upper lip. Both the upper and lower lip stiffness and tone were higher in females than in males, whereas upper lip elasticity was higher in males. Thinner upper lips had higher tone and were stiffer than thicker upper lips, whereas thinner lower lips were less elastic than thicker lower lips. Muscle tone and stiffness of both the upper and lower lips were lower in Class III than in Class I and Class II individuals. The upper lip of hyperdivergent individuals was less elastic than that of normodivergent and hypodivergent individuals, and stiffer than that of hypodivergent individuals.

CONCLUSIONS

The biomechanical properties of perioral soft tissues can be reliably measured and vary with anatomical site, sex, and cephalometric measurements.