STUDY DESIGN
Cross-sectional observational study.
BACKGROUND
Patients with chronic neck pain often perceive increased stiffness of their neck muscles; yet there is uncertainty as to whether people with neck pain present with evidence of an objective increase in neck muscle stiffness.
OBJECTIVES
Utilizing shear wave elastography, we compared the stiffness of the neck extensor muscles and stiffness in muscle-specific regions between women with chronic non-specific neck pain and asymptomatic controls.
METHODS
Muscle stiffness averaged over multiple neck extensor muscles and in regions corresponding approximately to the trapezius, splenius capitis, semispinalis capitis, semispinalis cervicis and multifidus muscles were measured using ultrasound shear wave elastography in 20 women with chronic non-specific neck pain and 18 asymptomatic women during multiple tasks. Measurements were automatically quality-controlled and computer-processed over the complete visible neck region or a large muscle-specific region.
RESULTS
Pooled over all tasks, neck muscle stiffness was not significantly different between those with neck pain and the asymptomatic group (median (interquartile range): 11.6 (8.9) kPa and 13.3 (8.6) kPa respectively; P= 0.175). The measure of neck muscle stiffness was not correlated with the intensity of neck pain or perceived disability.
CONCLUSIONS
Shear wave elastography revealed similar muscle stiffness in people with and without chronic neck pain despite the sensation of increased neck stiffness in those with chronic neck pain.
SIGNIFICANCE
Therapeutic interventions aiming to reduce neck muscle tone are often based on the assumption that perceived neck stiffness corresponds to objective muscle stiffness. The current results question this assumption. J Orthop Sports Phys Ther, Epub 6 Jan 2020. doi:10.2519/jospt.2020.8821.