Electromyographic activity of the cervical flexor muscles in patients with temporomandibular disorders while performing the craniocervical flexion test: a cross-sectional study

Abstract

Background: Most patients with temporomandibular disorders (TMD) have been shown to have cervical spine dysfunction. However, this cervical dysfunction has been evaluated only qualitatively through a general clinical examination of the cervical spine.

Purpose: The purpose of this study was to determine whether patients with TMD had increased activity of the superficial cervical muscles when performing the craniocervical flexion test (CCFT) compared with a control group of individuals who were healthy.

Design: A cross-sectional study was conducted.

Methods: One hundred fifty individuals participated in this study: 47 were healthy, 54 had myogenous TMD, and 49 had mixed TMD. All participants performed the CCFT. Data for electromyographic activity of the sternocleidomastoid (SCM) and anterior scalene (AS) muscles were collected during the CCFT for all participants. A 3-way mixed-design analysis of variance for repeated measures was used to evaluate the differences in EMG activity for selected muscles while performing the CCFT under 5 incremental levels. Effect size values were calculated to evaluate the clinical relevance of the results.

Results: Although there were no statistically significant differences in electromyographic activity in the SCM or AS muscles during the CCFT in patients with mixed and myogenous TMD compared with the control group, those with TMD tended to have increased activity of the superficial cervical muscles.

Limitations: The results obtained in this research are applicable for the group of individuals who participated in this study under the protocols used. They could potentially be applied to people with TMD having characteristics similar to those of the participants of this study.

Conclusion: This information may give clinicians insight into the importance of evaluation and possible treatment of the deep neck flexors in patients with TMD. However, future research should test the effectiveness of this type of program through a randomized controlled trial in people with TMD in order to determine the real value of treating this type of impairment in this population.

Figures

Figure 1.

Craniocervical flexion test.

Figure 2.

Normalized electromyographic (EMG) activity of sternocleidomastoid (SCM) and anterior scalene (AS) muscles in participants with myogenous temporomandibular disorders (TMD), those with mixed TMD, and those who were healthy while performing the craniocervical flexion test. Error bars=95% confidence interval. %MVC=percentage of maximum voluntary contraction, AvSCMR_22mmHg=average right SCM muscle EMG activity at 22 mm Hg, AvSCML_22mmHg=average left SCM muscle EMG activity at 22 mm Hg, AvASR_22mmHG=average right AS muscle EMG activity at 22 mm Hg, AvASL_22mmHg=average left AS muscle EMG activity at 22 mm Hg, AvSCMR_24mmHg=average right SCM muscle EMG activity at 24 mm Hg, AvSCML_24mmHg=average left SCM muscle EMG activity at 24 mm Hg, AvASR_24mmHg=average right AS muscle EMG activity at 24 mm Hg, AvASL_24mmHg=average left AS muscle EMG activity at 24 mm Hg, AvSCMR_26mmHg=average right SCM muscle EMG activity at 26 mm Hg, AvSCML_26mmHg=average left SCM muscle EMG activity at 26 mm Hg, AvASR_26mmHg=average right AS muscle EMG activity at 26 mm Hg, AvASL_26mmHg=average left AS muscle EMG activity at 26 mm Hg, AvSCMR_28mmHg=average right SCM muscle EMG activity at 28 mm Hg, AvSCML_28mmHg=average left SCM muscle EMG activity at 28 mm Hg, AvASR_28mmHg=average right AS muscle EMG activity at 28 mm Hg, AvASL_28mmHg=average left AS muscle EMG activity at 28 mm Hg, AvSCMR_30mmHg=average right SCM muscle EMG activity at 30 mm Hg, AvSCML_30mmHg=average left SCM muscle EMG activity at 30 mm Hg, AvASR_30mmHg=average right AS muscle EMG activity at 30 mm Hg, AvASL_30mmHg=average left AS muscle EMG activity at 30 mm Hg.

Figure 3.

Moderate effect sizes found for comparisons between participants with mixed temporomandibular disorders (TMD) and those who were healthy at different levels of pressure while performing the craniocervical flexion test. IV=inverse variance, 95% CI=95% confidence interval, ASR=right anterior scalene muscle, SCML=left sternocleidomastoid muscle, SCMR=right sternocleidomastoid muscle.

Figure 4.

Moderate effect sizes found for comparisons between participants with myogenous temporomandibular disorders (TMD) and those who were healthy at different levels of pressure while performing the craniocervical flexion test. IV=inverse variance, 95% CI=95% confidence interval, ASR=right anterior scalene muscle, SCML=left sternocleidomastoid muscle.