Technical Note
Comparison Between Neck and Shoulder Stiffness Determined by Shear Wave Ultrasound Elastography and a Muscle Hardness Meter

https://doi.org/10.1016/j.ultrasmedbio.2015.04.001Get rights and content

Abstract

The goals of this study were to compare neck and shoulder stiffness values determined by shear wave ultrasound elastography with those obtained with a muscle hardness meter and to verify the correspondence between objective and subjective stiffness in the neck and shoulder. Twenty-four young men and women participated in the study. Their neck and shoulder stiffness was determined at six sites. Before the start of the measurements, patients rated their present subjective symptoms of neck and shoulder stiffness on a 6-point verbal scale. At all measurement sites, the correlation coefficients between the values of muscle hardness indices determined by the muscle hardness meter and shear wave ultrasound elastography were not significant. Furthermore, individuals' subjective neck and shoulder stiffness did not correspond to their objective symptoms. These results suggest that the use of shear wave ultrasound elastography is essential to more precisely assess neck and shoulder stiffness.

Introduction

Neck and shoulder pain is a common complaint in the general population, and one of its initial symptoms is neck and shoulder stiffness (Ming et al. 2004). Neck and shoulder pain has a significant detrimental impact on health-related quality of life and physical functioning (Hill et al., 2010, Luo et al., 2004) and appears to relate to other disorders, such as headache and arm numbness or pain (Whiteley et al., 1993, Yeung et al., 2004). The objective evaluation of neck and shoulder stiffness is thus essential to find individuals who are at risk of neck and shoulder pain and to prevent neck and shoulder pain. A muscle hardness meter is often used to assess neck and shoulder stiffness (Arokoski et al., 2005, Ashina et al., 1999, Horikawa, 2001, Matsubara et al., 2011). In view of the powerful and potentially obfuscating influence of the hardness of subcutaneous adipose tissue and superficial muscles, however, there are doubts about whether this instrument is useful in evaluating the hardness of deep muscles.

Meanwhile, muscle elasticity has recently been quantified using shear wave ultrasound elastography (Akagi and Takahashi, 2013, Akagi and Takahashi, 2014, Akagi et al., 2014, Chernak et al., 2013, Maher et al., 2013, Nakamura et al., 2014). Kuo et al. (2013) determined neck muscle stiffness using shear wave ultrasound elastography and found that patients with chronic neck pain symptoms had a significantly stiffer trapezius muscle. However, they did not use the muscle hardness meter, and it is not clear whether the muscle hardness meter can measure neck and shoulder stiffness conveniently. In this study, therefore, we evaluated neck and shoulder stiffness using shear wave ultrasound elastography and the muscle hardness meter and compared the results. Given that the hardness of the masseter muscle assessed by ultrasound elastography was correlated with that determined with a muscle hardness meter (Ariji et al. 2013), we hypothesized that neck and shoulder stiffness evaluated by shear wave ultrasound elastography would correspond to that evaluated with a muscle hardness meter to some extent. In addition, individuals' subjective neck and shoulder stiffness was also determined to verify correspondence between objective and subjective neck and shoulder stiffness.

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Patients

After providing written informed consent, a total of 24 men (n = 12; age, 21 ± 1 y; body height, 172 ± 5 cm; body mass, 60 ± 6 kg; presented as mean ± standard deviation [SD]) and women (n = 12; age, 22 ± 1 y; body height, 159 ± 5 cm; body mass, 54 ± 5 kg) (all expressed as the mean ± standard deviation [SD]) without any orthopedic abnormalities of the neck and shoulders participated in the present study. The patients were either sedentary or physically active. The study protocol was approved

Results and Discussion

Descriptive data on the indices of muscle hardness are summarized in Table 1. None of the correlation coefficients between the values of muscle hardness indices determined with the muscle hardness meter and those determined with shear wave ultrasound elastography were significant (R1: r = 0.179, p = 0.404; R2: r = 0.208, p = 0.329; R3: r = 0.134, p = 0.532; L1: r = 0.085, p = 0.694; L2: r = 0.197, p = 0.357; L3: r = 0.330, p = 0.115). This result disproved the hypothesis that neck and shoulder

Acknowledgments

This study was partly supported by MEXT/JSPS KAKENHI Grant 24700689 (Grant-in-Aid for Young Scientists B).

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