Cervical Myofascial Pain Is Associated with an Imbalance of Masticatory Muscle Activity.

Michał Ginszt,Jacek Szkutnik,Apolinary Ginszt,Magdalena Bakalczuk,Grzegorz Zieliński,Małgorzata Stodółkiewicz,Piotr Majcher,Mansur Rahnama,Monika Litko-Rola

doi:10.3390/ijerph19031577

Abstract

This study aimed to assess the relationship between the occurrence of cervical myofascial pain with active myofascial trigger points (MTrPs) within the upper trapezius muscle and the electromyographic asymmetry index (AsI) of masticatory muscles: temporalis anterior (TA), superficial part of the masseter muscle (MM), and anterior belly of the digastric muscle (DA). The study group comprised 100 subjects (80 women and 20 men) aged 18 to 30 years (mean 23 ± 2.6 years) reporting pain in the neck muscles, diagnosed with myofascial pain with active MTrPs only within the upper trapezius muscle. The control group comprised 60 healthy, pain-free subjects (42 women and 18 men) aged 20 to 30 years (mean 22.8 ± 2.6 years) without MTrPs in the upper trapezius muscle. The palpation measurement, based on the diagnostic criteria of Travell and Simons, was used to diagnose active MTrPs. The masticatory muscle activity was recorded using an 8-channel device for surface electromyography—BioEMG IIITM. Significant differences in electromyographic patterns between the group with MTrPs in the right side of upper trapezius muscle and the control group were observed within resting activity for the AsI TA (MTrPs: 8.64 vs. controls: −3.22; p = 0.001) and AsI MM (MTrPs: 7.05 vs. controls: −2.09; p = 0.018). Controls presented different electromyographic patterns during maximum voluntary clenching with cotton rolls between teeth within masseter muscle compared to the MTrPs group (MTrPs: 9.27 vs. controls: −0.43 vs. p = 0.041). Participants with MTrPs in the left side of upper trapezius muscle presented predomination of left-sided electromyographic patterns at rest within temporalis anterior in comparison to controls (MTrPs: −19.22 vs. controls: −3.22; p = 0.001). MTrPs within the trapezius muscle may be related to asymmetry within the masticatory muscle activity, suggesting that the presence of myofascial pain within the cervical muscles plays a role in the imbalance of the stomatognathic system. A unilateral active MTrPs within the trapezius muscle may increase the sEMG activity on the same side of the temporalis anterior and masseter muscles.

Highlights

Myofascial pain is defined as a musculoskeletal disorder that causes pain in the area of a muscle and fascia
The pain can be characterized by multiple myofascial trigger points (MTrPs), which are defined as exquisitely tender spots in taut bands of a muscle or fascia that produce local and referred pain [1,2]
Statistical analysis showed that there was no significant difference between the group with active MTrPs in the upper trapezius muscle and the control group in terms of age (p = 0.235), maximum mouth opening (MMO) values (p = 0.263), and gender (p = 0.053)

Summary

Introduction

Myofascial pain is defined as a musculoskeletal disorder that causes pain in the area of a muscle and fascia. The pain can be characterized by multiple myofascial trigger points (MTrPs), which are defined as exquisitely tender spots in taut bands of a muscle or fascia that produce local and referred pain [1,2]. Trigger points are classified mainly as being active or latent [3]. Latent MTrPs may be converted to active MTrPs by continuous mechanical or chemical detrimental stimuli [4,5]. The most common causes of MTrPs are.

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