Viscoelasticity in trapezius myofascial pain syndrome: quantitative assessment using Real-Time Shear-Wave Elastography

Abstract

Objective

To investigate the differences in the viscoelastic properties between normal trapezius muscles and those in patients with trapezius myofascial pain syndrome (MPS) using real-time shear-wave elastography (SWE).

Materials and Methods

This study included 31 patients with trapezius MPS and 31 volunteers. Sixty-one trapezius muscles (41 and 20 on the affected and non-affected side, respectively) of patients with MPS and 62 normal trapezius muscles in volunteers were assessed. Conventional ultrasonic parameters, including skeletal muscle thickness, resistance index (RI), and mean shear wave velocity (SWV_mean) of trapezius muscles, were obtained in the seated position with the shoulders and neck relaxed. The daily neck leaning time (unit:hours) of all participants was obtained using a questionnaire.

Results

Ultrasound showed no statistically significant differences in thickness or RI of the trapezius muscles of the affected and non-affected sides in MPS patients versus normal trapezius muscles (p = 0.976 and 0.106, respectively). In contrast, the SWV_mean of trapezius muscles in patients with MPS was significantly higher than that of normal trapezius muscles in both the affected and non-affected sides (4.41 ± 1.02 m/s vs. 3.35 ± 0.79 m/s, p < 0.001; 4.05 ± 0.63 m/s vs. 3.35 ± 0.79 m/s, p = 0.002). There was no significant difference between the SWV_mean of the trapezius muscles on the affected and non-affected sides in patients with MPS (4.41 ± 1.02 m/s vs. 4.05 ± 0.63 m/s, p = 0.225). Correlation analysis showed that daily neck forward time was positively correlated with the SWV_mean of the trapezius muscles on the affected and non-affected sides in patients with MPS (r = 0.635, p < 0.001; r = 0.576, p = 0.008).

Conclusion

SWE can quantitatively evaluate stiffness of trapezius muscles in patients with trapezius MPS. The stiffness of both affected and non-affected trapezius muscles increased in patients with trapezius MPS, and the degree of increase positively correlated with the time of cervical forward leaning.

Keywords:

• Real-time shear-wave elastography
• trapezius myofascial pain syndrome
• stiffness

Author contributions

CJ Hao and QB Zhang participated in the conception and design of the experiments; CJ Hao, WL Xiao performed most of the experiments; XM Tan analyzed and interpreted the data; CJ Hao drafted the paper and critically revised it for intellectual content. All authors read and approved the final manuscript. And that all authors agree to be accountable for all aspects of the work.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All data used and analysed in the study are available by contacting the corresponding authors upon reasonable request.

Additional information

Funding

No funding was received.