Ultrasonographic analysis of dorsal neck muscles thickness changes induced by isometric contraction of shoulder muscles: A comparison between patients with chronic neck pain and healthy controls.

BACKGROUND: Altered pattern of muscle activity is commonly seen with chronic neck pain (CNP). However, limited investigations have been done on dorsal neck muscles' activity pattern while performing upper limb tasks in patients with CNP.

OBJECTIVES: To investigate dorsal neck muscles' thickness changes during isometric contraction of shoulder muscles.

DESIGN: Case-control study.

METHODS: This study investigated dorsal neck muscles' thickness changes during isometric contraction of shoulder muscles in 20 healthy participants (mean age 27 ± 4.37) and 17 patients with CNP (mean age 29 ± 5.50). Effects of isometric force of shoulder muscles on dorsal neck muscles' thickness changes were also evaluated.

RESULTS: Significant muscle × group interaction was observed for the dorsal neck muscles thickness changes (p = 0.008) indicating different pattern of muscle activity in terms of changes in muscle thickness of two groups. Significant main effects of direction was observed (P = 0.003), with the abduction had the greatest impact on changing the dorsal neck muscles thickness.

CONCLUSIONS: patients with CNP showed altered pattern of muscle thickness changes in comparison to healthy participants. Isometric abduction of shoulder muscles induced the greatest changes of dorsal neck muscles thickness among other force directions.