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

• Isometric abduction of shoulder muscles activates dorsal neck muscles more than other movement directions.
• In patients with non-specific CNP, more activity in Semispinalis muscle is seen compared to Multifidus.
• Among dorsal neck muscles, Splenius Capitis showed the most thickness changes during isometric contraction of shoulder muscles.

BackgroundAltered 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.ObjectivesTo investigate dorsal neck muscles' thickness changes during isometric contraction of shoulder muscles.DesignCase-control study.MethodsThis 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.ResultsSignificant 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.Conclusionspatients 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.