Cervical muscle volume in individuals with idiopathic neck pain compared to asymptomatic controls: A cross-sectional magnetic resonance imaging study

Abstract

BackgroundNeck muscle compositional changes may represent potential biomarkers contributing towards chronic neck-related pain and disability. ObjectivesTo determine differences in muscle volume in the cervical muscles of individuals with chronic idiopathic neck pain compared with age- and sex-matched asymptomatic individuals, and to determine if these muscle variables relate to spinal level, side (left or right), age, sex, body mass index (BMI) or muscle strength. Study designCross-sectional magnetic resonance imaging (MRI) study. MethodsMuscle volume of five muscle (groups) from cervical levels C3-T1 in 20 pain and 17 asymptomatic participants were quantified using MRI: levator scapulae, multifidus including semispinalis cervicis, semispinalis, splenius capitus including splenius cervicis, and sternocleidomastoid. Isometric extensor and flexor muscle strength were assessed with a dynamometer. Linear mixed modelling determined differences between groups in muscle volume accounting for participant characteristics. ResultsIndividuals with pain had greater muscle volume (adjusted mean difference 71.2 mm3 (95% CI 14.2–128.2, p = .015) of the sternocleidomastoid, accounting for spinal level, side, muscle group (extensors vs flexor), sex, age, body mass index and strength. Modelling indicated muscle volume differed between spinal levels (p < .001); greater extensor muscle strength was associated with greater volume (p = .011); female sex (p < .001) and older age (p = .012) were associated with less volume. ConclusionBetween-group differences in cervical flexor muscle volume, and volume differences across spinal levels and muscles suggest the contribution of cervical muscles to chronic idiopathic neck pain is multifaceted and complex.