Ultrasonographic analysis of the neck flexor muscles in patients with chronic neck pain and changes after cervical spine mobilization.

OBJECTIVE: The purpose of this study was to analyze changes in the recruitment of the muscles longus colli (Lco) and sternocledomastoid (SCM) as measured by ultrasonography in patients with chronic neck pain before and immediately after a single cervical Maitland's posterior-anterior central mobilization technique. METHODS: This was a cross-sectional, case-control research design study. Ultrasonographic images of Lco and SCM were taken in 31 patients with chronic neck pain and matched controls during the 5 phases of the craniocervical flexion test before and after a Maitland's posterior-anterior central mobilization session at the cervical spine. Changes in muscle thickness during the test were calculated to infer muscle recruitment. Separate analysis of variance models for each muscle was built. RESULTS: Both groups showed increases in Lco and SCM recruitment between phases (F = 7.95, P < .001; F = 21.29, P < .001), with patients with chronic neck pain demonstrating lesser increases for Lco changes in thickness compared with controls, mainly at phase 5 (-0.09, P = .004; 95% confidence interval [CI], 0.03-0.15). After the mobilization, Lco recruitment increased more significantly in patients with chronic neck pain, and previous difference between groups in phase 5 was no longer significant (-0.07, P = .07; 95% CI, -0.14 to 0.01). The SCM recruitment decreased in phase 1 for patients with chronic neck pain (P = .01; 95% CI, -0.06 to -0.01). CONCLUSION: Cervical mobilization appeared to modulate neck muscles function by increasing deep muscle and reducing superficial muscles recruitment.