Body position effects on EMG activity of sternocleidomastoid and masseter muscles in patients with myogenic cranio-cervical-mandibular dysfunction

A flexible adhesive surface electrode array capable of cervical electroneurography during a sequential autonomic stress challenge

This study introduces a flexible, adhesive-integrated electrode array that was developed to enable non-invasive monitoring of cervical nerve activity. The device uses silver-silver chloride as the electrode material of choice and combines it with an electrode array consisting of a customized biopotential data acquisition unit and integrated graphical user interface (GUI) for visualization of real-time monitoring. Preliminary testing demonstrated this electrode design can achieve a high signal to noise ratio during cervical neural recordings. To demonstrate the capability of the surface electrodes to detect changes in cervical neuronal activity, the cold-pressor test (CPT) and a timed respiratory challenge were employed as stressors to the autonomic nervous system. This sensor system recording, a new technique, was termed Cervical Electroneurography (CEN). By applying a custom spike sorting algorithm to the electrode measurements, neural activity was classified in two ways: (1) pre-to-post CPT, and (2) during a timed respiratory challenge. Unique to this work: (1) rostral to caudal channel position-specific (cephalad to caudal) firing patterns and (2) cross challenge biotype-specific change in average CEN firing, were observed with both CPT and the timed respiratory challenge. Future work is planned to develop an ambulatory CEN recording device that could provide immediate notification of autonomic nervous system activity changes that might indicate autonomic dysregulation in healthy subjects and clinical disease states.

Electromyographic changes in masseter and sternocleidomastoid muscles can be applied to diagnose of temporomandibular disorders: An observational study

Background

The diagnosis of temporomandibular disorders (TMDs) is an important part of the functional cerebrospinal technique (FCST). In addition, surface electromyography (sEMG) is an important candidate for diagnosing TMD. In FCST, despite the importance of the cranio-cervical-mandibular system, few sEMG parameters consider TMDs. Thus, this study evaluated the possibility of TMD diagnosis by sEMG.

Methods

The study was conducted as an assessor-blinded cross-sectional study. Each of 35 participants were recruited for patient group and normal group separately based on the Diagnostic Criteria for TMD Symptoms Questionnaire (DC/TMD SQ). The sEMG was measured by attaching electrodes to sternocleidomastoid muscles (SCMM) and masseter muscles (MM) before and after wearing the temporomandibular joint balance appliance (TBA).

Results

The percentage overlapping coefficient (POC) value of the healthy control group was increased compared with the TMD group. Receiver operating characteristic (ROC) analysis revealed that the area under the curve (AUC) value of the SCMM was greater than that of the MM. POC values before and after the SCMM also revealed significant changes compared to the MM.

Conclusion

This study showed that the sEMG measurement of the SCMM is useful for TMD diagnosis in traditional Korean medicine.

Effects of sitting posture and jaw clenching on neck and trunk muscle activities during typing

Neck pain is one of the most common musculoskeletal complaints. Evidence suggests that increased activities of neck and trunk muscles are one of the mechanisms related to neck pain. Jaw clenching and sitting posture may modulate the muscle activity in neck and trunk muscles during typing. The present study aimed to assess the effects of different postural positions and clenching conditions on neck and trunk muscle activities. Thirteen healthy adults (39.8 ± 5.0 years) performed computer typing tasks in four conditions (two postural positions [upright vs slouched] and two jaw clenching conditions [clenching vs non-clenching]). Integrated surface electromyography (iEMG) was measured in sternocleidomastoid (SCM), upper trapezius (uTP) and middle trapezius (mTP) muscles and compared between conditions. The Friedman and Wilcoxon signed-rank tests with Bonferroni's corrections were used to estimate the condition-specific differences in the iEMG data. The statistical significance level was set at 5%. In both postural positions, iEMG_SCM was significantly greater under the jaw clenching than under the non-clenching condition (χ²  = 21.700, P < .01). Under both jaw clenching conditions, iEMG_uTP was significantly greater in the slouched than in the upright postural position (χ²  = 23.182, P < .01). No significant differences in iEMG_mTP were seen across conditions (χ²  = 5.018, P = .10). Sitting posture and jaw clenching appear to influence activities of different muscles.

The clinical usefulness of surface electromyography in the diagnosis and treatment of temporomandibular disorders

BACKGROUND

This article presents a comprehensive review of the recent literature regarding the scientific support for the use of surface electromyography (SEMG) in diagnosing and treating temporomandibular disorders (TMDs).

TYPES OF STUDIES REVIEWED

The authors conducted a Medline search involving human studies using the key words "surface electromyography or electromyography" and "masticatory muscles or temporomandibular disorders or craniomandibular disorders." They also reviewed relevant articles regarding the clinical usefulness of SEMG based on reliability, validity, sensitivity and specificity, as well as additional references included in some of the articles.

RESULTS

The clinical use of SEMG in the diagnosis and treatment of TMD is of limited value when one considers reliability, validity, sensitivity and specificity as measurement standards. SEMG does not appear to contribute any additional information beyond what can be obtained from the patient history, clinical examination and, if needed, appropriate imaging.

CONCLUSIONS

Clinically, the determination of the presence or absence of TMD does not appear to be enhanced by the use of SEMG. However, the modality may be useful in a meticulously controlled research setting.

CLINICAL IMPLICATIONS

SEMG has limited value in the detection or management of TMD and in some instances may lead to unnecessary dental therapy as a solution for those disorders.

The effects of masseter muscle pain on biting performance

The present study applied a standardized test food of known hardness to evaluate the biting performance of 20 female patients who had pain mainly in the masseter muscle during palpation. Another 20 women of a similar age group who were pain-free during examination served as controls. Electromyograms (EMG) of the masseter and sternocleidomastoid (SCM) muscles and the jaw position were recorded and measured when the subjects were biting through two types of test foods with known hardness (hard type, 20 kg hardness and extra-hard type, 60 kg hardness). Pressure-pain-threshold (PPT) values of both the patients and the normal subjects were obtained with an algometer. It was found that the PPT of the patients with pain was significantly lower and that the extra-hard food took more masseter muscle activity and more working side jaw movement in both the pain and the normal groups. During both hard and extra-hard food biting, a significantly longer duration of masseter muscle activity was found in pain patients while the total muscle activity was not significantly stronger. Strong correlation existed between SCM and masseter muscle activity during both hard and extra-hard food biting in the patient group, while such correlation was very weak in the normal group. In conclusion, painful masseter muscles required longer masseter and SCM muscle contraction time for breaking through a hard food of 20 kg and more, and co-activation of SCM and masseter muscles existed and was more evident when the food was harder or the pain was more severe.

Possible manifestation of temporomandibular joint dysfunction on chiropractic cervical X-ray studies

OBJECTIVE

Our purpose was to show that biomechanical alterations toward and away from normal on x-ray studies may be the result of changes in temporomandibular joint dysfunction and to discuss possible neurologic explanations for this phenomenon.

CLINICAL FEATURES

Two patients are discussed; the first had migraine headache symptoms, and the second had chronic hypomobility of mandibular opening, dizziness, headache, and neck pain and stiffness. In both patients mensuration changes in different types of cervical x-ray studies were noted in conjunction with exacerbation of, and elimination of, temporomandibular joint dysfunction.

INTERVENTION

Comanagement of these cases was done with dental professionals. Chiropractic treatment included vectored/linear, upper cervical, high-velocity, low-amplitude chiropractic manipulation of the atlas vertebra, diversified manipulation, myofascial therapy, stretch and spray procedures, and soft tissue manual techniques.

CONCLUSION

Temporomandibular joint dysfunction may cause cervical muscular and spinal biomechanical changes that may become visible and change on x-ray examination. Further investigation into this phenomenon is recommended.