Is there altered activity of the extensor muscles in chronic mechanical neck pain? A functional magnetic resonance imaging study

Objective: To compare the pattern of neck extensor muscle use in participants with chronic mechanical neck pain to that of healthy controls during 2 different extension exercises by use of muscle functional magnetic resonance imaging (mfMRI). Design: Cross-sectional. Setting: University laboratory. Participants: Data recorded from subjects with chronic mechanical neck pain (n=12; 10 women, 2 men) were compared with previously recorded data from healthy subjects (n=11; 7 men, 4 women). Interventions: Not applicable. Main Outcome Measures: mfMRI measures of shifts in T2 relaxation were made for the multifidus, semispinalis cervicis, semispinalis capitis, and splenius capitis muscles, at C2-3, C5-6, and C7-T1 levels, prior and immediately after 2 different exercises: cervical extension in craniocervical neutral (CCN) and cervical extension in craniocervical extension. T2 shift values (difference between pre- and postexercise T2 relaxation values) for each muscle and exercise condition were used for analysis. Results: While there were observed differences in differential activation of the extensor muscles in participants with mechanical neck pain compared with controls, these differences were only evident for the CCN exercise condition and were only observed for 3 out of the 7 muscle regions of interest during this exercise. Conclusions: Results of this study suggest some alteration in the differential activation of the cervical extensors in patients with mechanical neck pain and indicate that further investigation of this muscle group in mechanical neck pain disorders is warranted.