To investigate changes in resting-state functional connectivity after physical exercise therapy for people with chronic neck pain, and whether changes are associated with self-reported outcome measures.
Prospective longitudinal study with 24 participants (18 female, mean age 39.7 years, mean pain duration 8.4 years) with chronic neck pain. All participants completed an 8-week physical exercise intervention consisting of three sessions per week. Self-reported outcome measures for pain intensity (visual analogue scale [VAS]) and pain-related disability (Neck Disability Index [NDI]), as well as resting state functional connectivity (blood oxygen-level dependent [BOLD]), were assessed at baseline and upon intervention completion. All scans were performed using a Siemens Magnetom Skyra 3-Tesla scanner, controlled by a clinical radiographer. BOLD images were analysed using the CONN Toolbox. Corrected p-values (False Discovery Rate [p-FDR]) were used to reduce the risk of introducing Type I errors.
After the exercise intervention, there were significant improvements in VAS (mean difference [SD]: 30.2 [20.5], 95% CI: 21.6 to 38.8, p.001) and NDI (mean difference [SD]: 9.3 [5.2], 95% CI: 7.1 to 11.5, p.001). Resting state functional connectivity changed in two region of interest connectivity pairs: 1) left inferior temporal gyrus and left juxtapositional lobule gyrus (Beta = 0.10, p-FDR = 0.039), and 2) right angular gyrus and right supracalcarine cortex (Beta = -0.26, p-FDR = 0.038). Neither of these connectivity changes was correlated with neck pain intensity, disability, or changes in these outcomes, nor with pain duration or sex.
Participants with neck pain demonstrated significantly and clinically meaningfully improved pain intensity and disability scores. We found changes in two functional connectivity pairs, indicating that exercise therapy may have an effect on neuronal activation patterns of various brain regions of interest. Whilst these changes occurred after the intervention, they were not related to clinical outcome measures. This study did not aim to assess the effectiveness of exercise therapy, so no control group or randomised approach was used, and changes could be due to natural recovery or external factors. However, high pain intensity and long duration of symptoms make it unlikely that spontaneous recovery coincided with the intervention, suggesting that the intervention contributed to the observed improvements.
These results provide insight into the central neurobiological effects of exercise therapy in individuals with chronic neck pain. Findings suggest that the role of the central nervous system in differential responses to exercise therapy should be further explored. Clinicians may consider the central effects of exercise therapy, especially for those patients for whom central mechanisms might contribute to differential outcomes.
Chronic pain
Exercise
