New method of neck surface electromyography for the evaluation of tongue-lifting activity

The mouth-opening muscular performance in adults and elderlies with and without dysphagia: A systematic review and meta-analysis

OBJECTIVES

To characterize mouth-opening muscular performance (MOMP) in adults and elderly individuals with dysphagia and healthy controls.

METHODS

We searched the PubMed, EMBASE, CINAHL, Cochrane, Scopus, and Web of Science databases from inception to Jan. 26, 2023. Two independent researchers considered the titles, abstracts, and full texts of potentially eligible papers from 1451 search results. Twenty-five studies that evaluated mouth-opening maximal strength (MOMS) in healthy adults, elderly individuals, and patients with dysphagia met the inclusion criteria.

RESULTS

We found comparable, reliable values with significant sex differences in maximal mouth opening strength (MMOS) in the meta-analysis for healthy elderly patients (females 5.31 ± 0.47 kg vs. males 7.04 ± 0.70 kg; mean difference of 0.84 kg). Age has also emerged as an essential factor in reducing strength. There was a significant reduction in the MMOS score in the only study that compared dysphagic individuals to healthy elderly individuals. In another study, the MMOS score was comparable to the meta-analysis of healthy elderly individuals.

CONCLUSIONS

Both sex and age play significant roles in the MMOS. There is no reliable data on the normal mouth-opening strength and endurance of healthy adults, patients with dysphagia, or individuals with other relevant clinical problems.

Visual evaluation for the elasticity of suprahyoid muscles using sonographic elastography during tongue pressure measurement: A pilot study

BACKGROUND

Suprahyoid muscles behavior during the tongue lifting movement has not yet been elucidated.

OBJECTIVE

The purpose of this study was to investigate the potential of elastography imaging to examine developmental oral dysfunction in children and oral hypofunction in older adults using sonography.

METHODS

Tongue pressure was measured using a manometer with a probe. The tongue pressure was measured with simultaneously scanning the geniohyoid muscle (GHM) and the anterior belly of the digastric muscle (DGM) using sonographic elastography. Sagittal images of the GHM and coronal images of the DGM were used for the strain ratio measurement. The strain ratio of the muscles was measured three times for each subject with the tongue pressure values of 0-30 kPa.

RESULTS

The strain ratio of the GHM were higher than those of the DGM at tongue pressure of 10, 20 and 30 kPa. The strain ratio of the GHM increased as the tongue pressure increased in all participants. In contrast, the strain ratio of the DGM tended to slowly decrease as tongue pressure increased in female participants.

CONCLUSION

Sonographic elastography is useful for visual and quantitative evaluation of elastic properties in suprahyoid muscles during tongue lifting movements.

Functional Role of Suprahyoid Muscles in Bolus Formation During Mastication

It still remains unclear how the suprahyoid muscles function in bolus formation during mastication. This study aimed to investigate the contributory role of the suprahyoid muscles during mastication. A total of 20 healthy young volunteers were asked to perform tongue pressure generation tasks and unilateral mastication tasks using peanuts and two different types of rice crackers. Surface electromyographic (EMG) activity of the masseter and suprahyoid muscles and mandibular kinematics were recorded. Suprahyoid activity increased with increasing tongue pressure. Masticatory duration until the first deglutition differed significantly among the different foods; the harder the food, the longer the duration. This was also the case in masseter activity per masticatory cycle. Masticatory rate and suprahyoid activity per masticatory cycle were significantly higher during soft rice cracker mastication. Masseter activity was higher on the masticatory side than on the non-masticatory side, however, there was no difference in suprahyoid activity between the sides. Suprahyoid activity and jaw gape showed significant positive correlation in the early stage on both the masticatory and non-masticatory sides. The suprahyoid muscles functioned dominantly for jaw-opening during peanut mastication, and for bolus formation, especially in the late stage during soft rice cracker mastication. Bolus formation was performed dominantly on the masticatory side during rice cracker mastication. These findings clearly demonstrate a functional role of the suprahyoid muscles during mastication of solid foods from assessments using both EMG activity and mandibular kinematic recordings.

The mouth-opening muscular performance in adults with and without temporomandibular disorders: A systematic review

Background

The mouth‐opening muscular performance in patients with temporomandibular disorders (TMDs) is unclear. Understanding the impairments of this muscle group within specific TMDs is important to develop proper management strategies.

Objective

To characterise the mouth‐opening muscular performance in adults with and without TMDs.

Methods

PubMed, EMBASE, CINAHL, Scopus, Web of Science and Cochrane databases were searched from inception to 12 November 2020. Bibliographies were searched for additional articles, including grey literature. Case‐control, cross‐sectional and interventional studies reporting mouth‐opening muscular strength and/or endurance were included. Risk of bias was assessed by the SIGN checklist for case‐control studies and by the NIH quality assessment tool for cross‐sectional studies. Results were pooled with a random‐effects model. Confidence in cumulative evidence was determined by means of the GRADE guidelines.

Results

Fourteen studies were included; most were rated as having a moderate risk of bias. Only three studies assessed patients with TMDs and the other 11 assessed healthy adults. Significant sex differences in muscular performance were found for healthy adults in the review (strength deficit for females versus males). There was a significant reduction in maximal mouth opening performance (strength and endurance) in the three studies that assessed patients with temporomandibular disorders.

Conclusion

Sex plays a significant role in maximal mouth opening strength. There is a lack of reliable data on the normal mouth‐opening strength and endurance of healthy adults as well as for patients with TMDs.

Implications

Lack of reliable TMDs patient data and comparable healthy adult data highlight future direction for research.

Detection of muscle fatigue caused by repeated posterior tongue lift movement from neck surface EMG: a pilot study

BACKGROUND

Fatigue is an important factor for muscle strengthening in rehabilitation medicine. Frequency analysis has been regarded as the gold standard for muscle fatigue assessment in surface electromyography (EMG). However, there are no experiments quantifying fatigue with grouped discharge (GD), which is one of the historical phenomena observed in patients having fatigue, by using high sampling rate recording of EMG.

OBJECTIVE

To investigate the effect of fatigue, which is induced by repeated posterior tongue lift movement (TLM), on the occurrence of GD peaks, thus, to provide possible basis as a parameter for future fatigue evaluation.

METHODS

Nineteen healthy adults (9 men and 10 women) participated in this study. The muscle fatigue protocol consisted of repetitive posterior TLM and maximum voluntary contractions (MVC). Bilateral N-EMG (Neck surface EMG for measuring the muscle activity of the posterior tongue) was recorded.

RESULTS

Subjective tongue fatigue at the end of the protocol was significantly higher than at beginning throughout the muscle fatigue protocol (p < .01). The frequency of occurrence of GD peaks was 0.9 ± 1.2 (per second) at the baseline in 33 of 38 subject sides, and significantly increased depending on fatigue progression (p < .01).

CONCLUSION

It was shown that fatigue due to repetitive posterior tongue lifting resulted in significant increase in the frequency of occurrence of GD peaks. Especially, the nature of GD, showing very few occurrences at non-fatigue condition, might work as an advantageous property for its use in future absolute evaluation of fatigue phenomena.

Coordination of surface electromyography activity in the posterior tongue region during mastication of differently textured foods

BACKGROUND

Masticatory movement occurs complicatedly and bilaterally. Although the tongue plays an important role in mastication, bilateral tongue function during mastication has not been clarified yet.

OBJECTIVE

To investigate the effect of food properties on posterior tongue activity and coordination of muscles bilaterally by electromyography (EMG).

METHODS

Twenty healthy adults (10 males and 10 females; mean age 28 years; range: 22-33 years) participated in this study. Three test foods, gummy jelly (hard food), sponge cake (soft food requiring crushing), and mashed potatoes (soft food not requiring crushing), were used. Bilateral masseter N-EMG (surface electromyography for measuring the muscle activity of posterior tongue) and submental EMG were carried out while the participants chewed three test foods. The participants were instructed to masticate three test foods only on the right side and only on the left side unilaterally.

RESULTS

In the case of gummy jelly, N-EMG activity on the mastication side was significantly larger than that on the non-mastication side (P < .01). Regarding temporal relationship between the masseter and N-EMG activity, in the case of gummy jelly, the percentage of cases where the N-EMG peak was observed during masseter muscle EMG bursts was significantly higher than those for sponge cake and mashed potatoes (P < .01).

CONCLUSION

N-EMG activity on the mastication side was significantly larger than that on the non-mastication side in the mastication of hard foods. Tongue showed activity pattern changes and coordinated with the masseter muscle depending on food texture.

Relationship between tongue pressure and back muscle strength in healthy elderly individuals

BACKGROUND

Aging is associated with a decrease in muscle mass and strength in swallowing muscles, as well as in whole-body muscles. A decrease in tongue pressure (TP) is related with whole-body function, and the trunk, including abdominal and back muscles, forms the core of the body. However, the direct relationship between TP and trunk muscle strength remains unclear.

AIMS

To clarify the association between back muscle strength, an indicator of trunk muscle strength, and TP in healthy elderly individuals.

METHODS

In all, 112 healthy community-dwelling individuals aged ≥ 60 years (men: 35, median age 74.0; women: 77, median age 69.0) were included. Body mass index (BMI), TP, and back muscle strength (BMS) were measured. Tooth loss pattern was evaluated by the Eichner classification. Participants were divided into two groups based on the median of the BMS and classified into three groups based on the Eichner index (Eichner A, B, and C). The effects of BMS and occlusal support on TP were analyzed.

RESULTS

In the low BMS group, there was a significant difference in TP between the Eichner B and Eichner C (p = 0.017) groups. However, in the high BMS group, occlusal support did not affect TP. Moreover, the explanatory factors for TP were BMS (β = 0.373, p = 0.001) and the Eichner index (β = 0.190, p = 0.036).

CONCLUSIONS

TP was correlated more with BMS than aging and occlusal support in healthy elderly individuals. This study indicated that the clinical evaluation of the whole body is important when assessing oral and swallowing function.

Validation of the optimal site in the neck region for detecting swallowing sounds

Recently, the swallowing sound has been used to detect swallowing events non-invasively. A previous study, using an accelerometer, showed that the site over the lateral border of the trachea immediately inferior to the cricoid cartilage was the optimal site for detecting swallowing sounds. However, the optimal site for detection of the swallowing sound using a microphone remains undetermined. To validate the optimal site in the neck region for detecting swallowing sounds. Fourteen healthy subjects (mean age, 27·6 ± 2·2 years; seven male and seven female) participated in this study. Twenty condenser microphones were attached to 20 sites on the left neck surface to detect swallowing sounds. Participants were instructed to swallow five different stimuli three times as follows: Resting saliva, 1 and 5 mL of Japanese tea, and 1 and 5 mL of yoghurt. Mean relative peak intensity was used to indicate the magnitude of the swallowing sound. Sound spectrograms were used to illustrate differences in the properties of swallowing sounds. Mean relative peak intensity number was highest in sites at the inferior border of the mandible just above the sternocleidomastoid muscle (site 11) and sites over the lateral border of the trachea immediately inferior to the cricoid cartilage (site 8). Comparison of spectrograms showed a greater density distribution of higher frequency components at site 11 compared with site 8. These results indicate that the inferior border of the mandible just above the sternocleidomastoid muscle is the optimal site for the detection of swallowing sounds.